Particulate matter

{{Short description|Microscopic solid or liquid matter suspended in the Earth's atmosphere}} {{Hatnote group| {{About|particles suspended in air|general discussion of particulate types|Particle#Distribution of particles}} {{Redirect|Particulates|other uses}} }} {{Use dmy dates|date=November 2025}} [[File:PM and a human hair.jpg|alt=A computer graphic showing how many PM{{sub|10}} particles can be wrapped around a human hair and how several PM{{sub|2.5}} particles can be wrapped around PM{{sub|10}}|thumb|PM{{sub|2.5}} and PM{{sub|10}} compared with a human hair in a graphic from the Environmental Protection Agency]] {{Pollution sidebar|Air}}

'''Particulate matter''' (PM) or '''particulates'''{{efn|Also known as "atmospheric particulate matter", "atmospheric aerosol particles" or "suspended particulate matter" (SPM)}} are microscopic particles of solid or liquid matter, which are suspended in the air. An ''aerosol'' is a mixture of particulates and air, as opposed to the particulate matter itself.<ref name="Hinds"/> Sources of particulate matter can be natural or result from human activities. Particulates adversely affect human health and have impacts on climate and precipitation.

Categories of atmospheric particles include inhalable coarse particles, designated '''PM{{sub|10}}''', which are coarse particles with a diameter of 10 micrometers (μm) or less; fine particles, designated '''PM{{sub|2.5}}''', with a diameter of 2.5 μm or less;<ref name="US EPA">{{cite web |last1=US EPA |first1=OAR |date=30 May 2025 |title=Particulate Matter (PM) Basics |url=https://www.epa.gov/pm-pollution/particulate-matter-pm-basics#PM |url-status=live |archive-url=https://web.archive.org/web/20230929080902/https://www.epa.gov/pm-pollution/particulate-matter-pm-basics#PM |archive-date=29 September 2023 |access-date=26 August 2025 |website=Particulate Matter (PM) Pollution |publisher=United States Environmental Protection Agency}}</ref> ultrafine particles, '''PM{{sub|.10}}''' with a diameter of 100 nanometers (nm) or less; and soot (fine or ultrafine particles primarily made up of carbon).<ref name="Hamanaka">{{Cite journal |last1=Hamanaka |first1=RB |last2=Mutlu |first2=GM |date=2025-09-02 |title=Particulate matter air pollution: effects on the respiratory system |journal=The Journal of Clinical Investigation |volume=135 |issue=17 |article-number=e194312 |doi=10.1172/JCI194312 |issn=1558-8238 |pmc=12404767 |pmid=40892514}}</ref>

Airborne particulate matter is a Group 1 carcinogen.<ref name="Arif">{{cite journal |last1=Arif |first1=I |last2=Adams |first2=MD |last3=Johnson |first3=MTJ |title=A meta-analysis of the carcinogenic effects of particulate matter and polycyclic aromatic hydrocarbons. |journal=Environmental Pollution |date=15 June 2024 |volume=351 |article-number=123941 |doi=10.1016/j.envpol.2024.123941 |pmid=38614427 |bibcode=2024EPoll.35123941A }}</ref> Particulate matter is considered the most dangerous type of air pollution<ref name="Bodor">{{cite journal |last1=Bodor |first1=K |last2=Szép |first2=R |last3=Bodor |first3=Z |title=The human health risk assessment of particulate air pollution (PM(2.5) and PM(10)) in Romania. |journal=Toxicology Reports |date=2022 |volume=9 |pages=556–562 |doi=10.1016/j.toxrep.2022.03.022 |pmid=35386513 |pmc=8978270 }}</ref><ref name="Kelly">{{cite journal |last1=Kelly |first1=FJ |last2=Fussell |first2=JC |title=Toxicity of airborne particles-established evidence, knowledge gaps and emerging areas of importance. |journal=Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences |date=30 October 2020 |volume=378 |issue=2183 |article-number=20190322 |doi=10.1098/rsta.2019.0322 |pmid=32981440 |pmc=7536031 |bibcode=2020RSPTA.37890322K }}</ref> because particulates can penetrate deep into the lungs and travel through the blood stream to multiple organs including the brain.<ref name="Błaszczak">{{cite journal |last1=Błaszczak |first1=B |last2=Słaby |first2=K |last3=Rogula-Kopiec |first3=P |title=The role of fine and submicron aerosol particles in urban air pollution in the context of meeting new air quality standards. |journal=Scientific Reports |date=2 December 2025 |volume=16 |issue=1 |page=915 |doi=10.1038/s41598-025-30407-5 |pmid=41331033 |pmc=12783275 }}</ref><ref name="Kelly" /><ref name="Gimeno">{{cite journal |last1=Gimeno-Ferrer |first1=F |last2=Porschen |first2=LT |last3=Matthes |first3=F |last4=Gohlsch |first4=K |last5=Meissner |first5=A |title=Airborne particulates and brain health: The role of PM(2.5) in blood-brain-barrier dysfunction. |journal=Journal of Cerebral Blood Flow and Metabolism |date=8 February 2026 |volume=46 |issue=5 |article-number=271678X261418925 |doi=10.1177/0271678X261418925 |pmid=41656668 |pmc=12885965 }}</ref> Particulate matter contributes to health problems such as stroke, heart disease, lung disease, cancer, and preterm birth.<ref name=":7">{{Cite journal |vauthors=Thangavel P, Park D, Lee YC |date=19 June 2022 |title=Recent Insights into Particulate Matter (PM2.5)-Mediated Toxicity in Humans: An Overview |journal=Int. J. Environ. Res. Public Health |type=Review |language=en |volume=19 |issue=12 |page=7511 |doi=10.3390/ijerph19127511 |pmc=9223652 |pmid=35742761 |doi-access=free}}</ref> There is no safe level for exposure to particulates.<ref name="Hamanaka" />

Worldwide, exposure to PM{{sub|2.5}} contributed to 7.9 million deaths in 2023, of which 4.9 million were from outdoor air pollution and 2.8 million from household air pollution.<ref name="SOGA2025" /> Fine particulate matter (PM{{sub|2.5}}) is considered the leading environmental risk factor for earlier death worldwide.<ref name="Hamanaka" /><ref name="Burnett">{{cite journal |last1=Burnett |first1=R |last2=Chen |first2=H |last3=Szyszkowicz |first3=M |last4=Fann |first4=N |last5=Hubbell |first5=B |last6=Pope CA |first6=3rd |last7=Apte |first7=JS |last8=Brauer |first8=M |last9=Cohen |first9=A |last10=Weichenthal |first10=S |last11=Coggins |first11=J |last12=Di |first12=Q |last13=Brunekreef |first13=B |last14=Frostad |first14=J |last15=Lim |first15=SS |last16=Kan |first16=H |last17=Walker |first17=KD |last18=Thurston |first18=GD |last19=Hayes |first19=RB |last20=Lim |first20=CC |last21=Turner |first21=MC |last22=Jerrett |first22=M |last23=Krewski |first23=D |last24=Gapstur |first24=SM |last25=Diver |first25=WR |last26=Ostro |first26=B |last27=Goldberg |first27=D |last28=Crouse |first28=DL |last29=Martin |first29=RV |last30=Peters |first30=P |last31=Pinault |first31=L |last32=Tjepkema |first32=M |last33=van Donkelaar |first33=A |last34=Villeneuve |first34=PJ |last35=Miller |first35=AB |last36=Yin |first36=P |last37=Zhou |first37=M |last38=Wang |first38=L |last39=Janssen |first39=NAH |last40=Marra |first40=M |last41=Atkinson |first41=RW |last42=Tsang |first42=H |last43=Quoc Thach |first43=T |last44=Cannon |first44=JB |last45=Allen |first45=RT |last46=Hart |first46=JE |last47=Laden |first47=F |last48=Cesaroni |first48=G |last49=Forastiere |first49=F |last50=Weinmayr |first50=G |last51=Jaensch |first51=A |last52=Nagel |first52=G |last53=Concin |first53=H |last54=Spadaro |first54=JV |title=Global estimates of mortality associated with long-term exposure to outdoor fine particulate matter. |journal=Proceedings of the National Academy of Sciences of the United States of America |date=18 September 2018 |volume=115 |issue=38 |pages=9592–9597 |doi=10.1073/pnas.1803222115 |doi-access=free |pmid=30181279 |pmc=6156628 |bibcode=2018PNAS..115.9592B |quote="Specifically the global estimates of mortality attributable to ambient fine particulate air pollution (8.9 million, 95% CI: 7.5–10.3) were 120% higher than previous estimates and suggest comparable impact to the leading global mortality risk factors of diet (10.3 million deaths, 95% CI: 8.8–11.9) and cigarette smoking (6.3 million deaths; 95% CI: 5.7–7.0)."}}</ref><ref name="GBD">{{cite journal |author=((GBD 2017 Risk Factor Collaborators)) |title=Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. |journal=Lancet |date=10 November 2018 |volume=392 |issue=10159 |pages=1923–1994 |doi=10.1016/S0140-6736(18)32225-6 |pmid=30496105 |pmc=6227755 |bibcode=2018Lanc..392.1923S }}</ref> Because many sources of particulates result from human actions, it is a modifiable risk factor which can be addressed. Many countries have established standards for particulate matter and are improving air quality.

==Sources== upright=1.45|Types, and size distribution in micrometres (μm), of atmospheric particulate matter|thumb [[File:Dust emission when using electrical power tools.webm|thumb|upright|Particulate emission when using modern electrical power tool during home broadband installation, Tai Po, Hong Kong]] [[File:Warsaw_Excavator_006.jpg|thumb|Excavator (a type of heavy equipment commonly used at construction sites and roadworks) demolishing the remnants of the pre-war Postal Train 0880Station (Dworzec Pocztowy) at Jerozolimskie Avenue, Poland]]

Approximately 90 percent of the total mass of particulate matter in the atmosphere (as estimated in 2010) comes from natural sources such as volcanoes, dust storms, forest and grassland fires, living vegetation and sea spray, emitting particulates such as volcanic ash, desert dust, soot and sea salt.<ref name="Chin">{{cite book |last1=Chin |first1=Mian |title=Atmospheric Aerosol Properties and Climate Impacts |date=2009 |publisher=U.S. Climate Change Science Program |page=10 |url=https://ntrs.nasa.gov/api/citations/20090032661/downloads/20090032661.pdf |access-date=19 March 2026}}</ref> Human-contributed (anthropogenic) particulate matter accounts for the remaining 10 percent of the total mass of aerosols.<ref name="Chin"/> Human activities that generate particulates include: * Burning of fossil fuels (coal, oil, and natural gas) for electricity, heat and transportation,<ref name="Lelieveld">{{cite journal |last1=Lelieveld |first1=J |last2=Haines |first2=A |last3=Burnett |first3=R |last4=Tonne |first4=C |last5=Klingmüller |first5=K |last6=Münzel |first6=T |last7=Pozzer |first7=A |title=Air pollution deaths attributable to fossil fuels: observational and modelling study. |journal=BMJ (Clinical Research Ed.) |date=29 November 2023 |volume=383 |article-number=e077784 |doi=10.1136/bmj-2023-077784 |pmid=38030155 |pmc=10686100 }}</ref><ref name=":5">{{cite journal |last1=Lee |first1=Giyoon |last2=Ahn |first2=Jinho |last3=Park |first3=Seung-Myung |last4=Moon |first4=Jonghan |last5=Park |first5=Rokjin |last6=Sim |first6=Min Sub |last7=Choi |first7=Hanna |last8=Park |first8=Jinsoo |last9=Ahn |first9=Joon-Young |title=Sulfur isotope-based source apportionment and control mechanisms of PM2.5 sulfate in Seoul, South Korea during winter and early spring (2017–2020) |journal=Science of the Total Environment |date=December 2023 |volume=905 |article-number=167112 |doi=10.1016/j.scitotenv.2023.167112 |pmid=37717778 }}</ref><ref name="pmid37995235">{{cite journal |vauthors=Henneman L, Choirat C, Dedoussi I, Dominici F, Roberts J, Zigler C |title=Mortality risk from United States coal electricity generation |journal=Science |volume=382 |issue=6673 |pages=941–946 |date=November 2023 |pmid=37995235 |pmc=10870829 |doi=10.1126/science.adf4915 |bibcode=2023Sci...382..941H |url=}}</ref> biomass fuels (plants, wood, crop residue and manure) for heating and cooking,<ref name="Eriksson2022">{{cite journal |last1=Eriksson |first1=A |last2=Abera |first2=A |last3=Malmqvist |first3=E |last4=Isaxon |first4=C |title=Characterization of fine particulate matter from indoor cooking with solid biomass fuels. |journal=Indoor Air |date=November 2022 |volume=32 |issue=11 |article-number=e13143 |doi=10.1111/ina.13143 |pmid=36437670 |pmc=9828024 |bibcode=2022InAir..3231.R2E }}</ref><ref name=":6">{{cite journal |last1=Roy |first1=Rajarshi |last2=Schooff |first2=Brian |last3=Li |first3=Xiaolong |last4=Montgomery |first4=Scott |last5=Tuttle |first5=Jacob |last6=Wendt |first6=Jost O. L. |last7=Dickson |first7=Kingsley |last8=Iverson |first8=Brian |last9=Fry |first9=Andrew |title=Ash aerosol particle size distribution, composition, and deposition behavior while co-firing coal and steam-exploded biomass in a 1.5 MWth combustor |journal=Fuel Processing Technology |date=May 2023 |volume=243 |article-number=107674 |doi=10.1016/j.fuproc.2023.107674 }}</ref><ref name="Yun">{{cite journal |last1=Yun |first1=X |last2=Shen |first2=G |last3=Shen |first3=H |last4=Meng |first4=W |last5=Chen |first5=Y |last6=Xu |first6=H |last7=Ren |first7=Y |last8=Zhong |first8=Q |last9=Du |first9=W |last10=Ma |first10=J |last11=Cheng |first11=H |last12=Wang |first12=X |last13=Liu |first13=J |last14=Wang |first14=X |last15=Li |first15=B |last16=Hu |first16=J |last17=Wan |first17=Y |last18=Tao |first18=S |title=Residential solid fuel emissions contribute significantly to air pollution and associated health impacts in China. |journal=Science Advances |date=October 2020 |volume=6 |issue=44 |article-number=eaba7621 |doi=10.1126/sciadv.aba7621 |pmid=33115732 |pmc=7608780 |bibcode=2020SciA....6.7621Y }}</ref> waste,<ref>{{cite journal | last1=Ramadan | first1=Bimastyaji Surya | last2=Rosmalina | first2=Raden Tina | last3=Syafrudin | last4=Munawir | last5=Khair | first5=Hafizhul | last6=Rachman | first6=Indriyani | last7=Matsumoto | first7=Toru | title=Potential Risks of Open Waste Burning at the Household Level: A Case Study of Semarang, Indonesia | journal=Aerosol and Air Quality Research | publisher=Taiwan Association for Aerosol Research | volume=23 | issue=5 | year=2023 | doi=10.4209/aaqr.220412 | article-number=220412 | bibcode=2023AAQR...23v0412R }}</ref> joss paper,<ref>{{cite journal |vauthors=Lin C, Huang RJ, Duan J, Zhong H, Xu W, Wu Y, Zhang R |title=Large contribution from worship activities to the atmospheric soot particles in northwest China |journal=Environ Pollut |volume=299 |issue= |article-number=118907 |date=April 2022 |pmid=35091017 |doi=10.1016/j.envpol.2022.118907 |bibcode=2022EPoll.29918907L }}</ref><ref>{{cite journal |last1=Giang |first1=Lam Van |last2=Thanh |first2=Tran |last3=Hien |first3=Truong Thanh |last4=Tan |first4=Lam Van |last5=Thi Bich Phuong |first5=Tran |last6=Huu Loc |first6=Ho |title=Heavy metals emissions from joss paper burning rituals and the air quality around a specific incinerator |journal=Materials Today: Proceedings |date=2021 |volume=38 |pages=2751–2757 |doi=10.1016/j.matpr.2020.08.686 }}</ref><ref name="pmid27764746">{{cite journal |vauthors=Shen H, Tsai CM, Yuan CS, Jen YH, Ie IR |title=How incense and joss paper burning during the worship activities influences ambient mercury concentrations in indoor and outdoor environments of an Asian temple? |journal=Chemosphere |volume=167 |issue= |pages=530–540 |date=January 2017 |pmid=27764746 |doi=10.1016/j.chemosphere.2016.09.159 |bibcode=2017Chmsp.167..530S |url=}}</ref> and firecrackers.<ref name="pmid31290418">{{cite journal |vauthors=Shah R, Limaye S, Ujagare D, Madas S, Salvi S |title=Personal exposures to particulate matter <2.5 μm in mass median aerodynamic diameter (PM{{sub|2.5}}) pollution during the burning of six most commonly used firecrackers in India |journal=Lung India |volume=36 |issue=4 |pages=324–329 |date=2019 |pmid=31290418 |pmc=6625239 |doi=10.4103/lungindia.lungindia_440_18 |doi-access=free |url=}}</ref> * Construction and renovation (including earthwork and foundation, demolition and rehabilitation).<ref>{{cite journal |last1=Cheriyan |first1=D |last2=Choi |first2=J |title=A review of research on particulate matter pollution in the construction industry |journal=Journal of Cleaner Production |date=1 May 2020 |volume=254 |article-number=120077 |doi=10.1016/j.jclepro.2020.120077 |bibcode=2020JCPro.25420077C |url=https://www.sciencedirect.com/science/article/abs/pii/S0959652620301244 |issn=0959-6526}}</ref><ref name="Fang">{{cite journal |last1=Fang |first1=Xingyue |last2=Chang |first2=Ruidong |last3=Zhang |first3=Yanquan |last4=Zuo |first4=Jian |last5=Zou |first5=Yang |last6=Han |first6=Yilong |title=Monitoring airborne particulate matter from building construction: A systematic review |journal=Journal of Building Engineering |date=1 June 2024 |volume=86 |article-number=108708 |doi=10.1016/j.jobe.2024.108708 |url=https://www.sciencedirect.com/science/article/pii/S2352710224002766 |issn=2352-7102}}</ref><ref>{{cite journal |last1=Yan |first1=H |last2=Li |first2=Q |last3=Feng |first3=K |last4=Zhang |first4=L |title=The characteristics of PM emissions from construction sites during the earthwork and foundation stages: an empirical study evidence. |journal=Environmental Science and Pollution Research International |date=May 2023 |volume=30 |issue=22 |pages=62716–62732 |doi=10.1007/s11356-023-26494-4 |pmid=36947374 |pmc=10167100 |bibcode=2023ESPR...3062716Y }}</ref><ref name="Halvorsen">{{cite journal |last1=Halvorsen |first1=JØ |last2=Graff |first2=P |last3=Gjengedal |first3=ELF |last4=Ervik |first4=TK |title=Measurements of dust and respirable crystalline silica during indoor demolition and renovation. |journal=Annals of Work Exposures and Health |date=8 January 2025 |volume=69 |issue=1 |pages=48–58 |doi=10.1093/annweh/wxae082 |pmid=39436770 |pmc=11706796 }}</ref><ref>{{Cite web |url=https://www.epd.gov.hk/epd/sites/default/files/epd/english/environmentinhk/air/guide_ref/files/construction_dust.pdf |title=Cut down construction dust}}</ref> * Dusty materials that are not properly stored, cleaned up or disposed of (from construction sites, landfills, industrial facilities, and households).<ref name="EPA2022">{{cite web |title=Fugitive Dust Control Measures and Best Practices |url=https://www.epa.gov/system/files/documents/2022-02/fugitive-dust-control-best-practices.pdf |website=United States Environmental Protection Agency |date=2022|access-date=18 March 2026}}</ref><ref name="Abubakar">{{cite journal |last1=Abubakar |first1=IR |last2=Maniruzzaman |first2=KM |last3=Dano |first3=UL |last4=AlShihri |first4=FS |last5=AlShammari |first5=MS |last6=Ahmed |first6=SMS |last7=Al-Gehlani |first7=WAG |last8=Alrawaf |first8=TI |title=Environmental Sustainability Impacts of Solid Waste Management Practices in the Global South. |journal=International Journal of Environmental Research and Public Health |date=5 October 2022 |volume=19 |issue=19 |article-number=12717 |doi=10.3390/ijerph191912717 |doi-access=free|pmid=36232017 |pmc=9566108 }}</ref><ref>{{Cite web|url=https://www.epd.gov.hk/epd/misc/popup/greenexample/A_TS_C4_folder/a_ts_c4.html|title=Proper Covering of Dusty Material on Dump Trucks|website=www.epd.gov.hk|access-date=4 July 2023|archive-date=4 July 2023|archive-url=https://web.archive.org/web/20230704092536/https://www.epd.gov.hk/epd/misc/popup/greenexample/A_TS_C4_folder/a_ts_c4.html|url-status=live}}</ref> * Waste incineration.<ref name="Tait">{{cite journal |last1=Tait |first1=PW |last2=Brew |first2=J |last3=Che |first3=A |last4=Costanzo |first4=A |last5=Danyluk |first5=A |last6=Davis |first6=M |last7=Khalaf |first7=A |last8=McMahon |first8=K |last9=Watson |first9=A |last10=Rowcliff |first10=K |last11=Bowles |first11=D |title=The health impacts of waste incineration: a systematic review. |journal=Australian and New Zealand Journal of Public Health |date=February 2020 |volume=44 |issue=1 |pages=40–48 |doi=10.1111/1753-6405.12939 |pmid=31535434}}</ref> * Concrete.<ref name="pmid32128461">{{cite journal |vauthors=Kholodov A, Zakharenko A, Drozd V, Chernyshev V, Kirichenko K, Seryodkin I, Karabtsov A, Olesik S, Khvost E, Vakhnyuk I, Chaika V, Stratidakis A, Vinceti M, Sarigiannis D, Hayes AW, Tsatsakis A, Golokhvast K |title=Identification of cement in atmospheric particulate matter using the hybrid method of laser diffraction analysis and Raman spectroscopy |journal=Heliyon |volume=6 |issue=2 |article-number=e03299 |date=February 2020 |pmid=32128461 |pmc=7042420 |doi=10.1016/j.heliyon.2020.e03299 |doi-access=free |bibcode=2020Heliy...603299K |url=}}</ref> * Metalworking (grinding, cutting, welding).<ref name="Buljat">{{cite journal |last1=Buljat |first1=A |last2=Čargonja |first2=M |last3=Mekterović |first3=D |title=Source Apportionment of Particulate Matter in a Metal Workshop. |journal=International Journal of Environmental Research and Public Health |date=13 June 2024 |volume=21 |issue=6 |page=768 |doi=10.3390/ijerph21060768 |doi-access=free|pmid=38929014 |pmc=11203473 }}</ref><ref>{{cite journal |last1=Levilly |first1=R |last2=Sauvain |first2=JJ |last3=Andre |first3=F |last4=Demange |first4=V |last5=Bourgkard |first5=E |last6=Wild |first6=P |last7=Hopf |first7=NB |title=Characterization of occupational inhalation exposures to particulate and gaseous straight and water-based metalworking fluids. |journal=Scientific Reports |date=13 August 2024 |volume=14 |issue=1 |page=18814 |doi=10.1038/s41598-024-69677-w |pmid=39138292 |pmc=11322652 |bibcode=2024NatSR..1418814L }}</ref> * Woodworking (sawing, sanding, and planing).<ref name="Basinas">{{cite journal |last1=Basinas |first1=I |last2=Liukkonen |first2=T |last3=Sigsgaard |first3=T |last4=Andersen |first4=NT |last5=Vestergaard |first5=JM |last6=Galea |first6=KS |last7=van Tongeren |first7=M |last8=Wiggans |first8=R |last9=Savary |first9=B |last10=Eduard |first10=W |last11=Kolstad |first11=HA |last12=Vested |first12=A |last13=Kromhout |first13=H |last14=Schlünssen |first14=V |title=Development of a quantitative North and Central European job exposure matrix for wood dust. |journal=Annals of Work Exposures and Health |date=6 July 2023 |volume=67 |issue=6 |pages=758–771 |doi=10.1093/annweh/wxad021 |pmid=37167588 |pmc=10795000 }}</ref><ref>{{cite web |title=Woodworking Dust Control: A Practical Guide to Safety, Compliance, and Cleaner Air |url=https://www.cecoenviro.com/woodworking-dust-control-a-practical-guide-to-safety-compliance-and-cleaner-air/ |website=CECO Environmemental |access-date=18 March 2026}}</ref> * Industrial processes such as quarrying,<ref name="Pham">{{cite journal |last1=Pham |first1=TTK |last2=Le |first2=SH |last3=Nguyen |first3=T |last4=Balasubramanian |first4=R |last5=Tran |first5=PTM |title=Characteristics of airborne particles in stone quarrying areas: Human exposure assessment and mitigation. |journal=Environmental Research |date=15 March 2024 |volume=245 |article-number=118087 |doi=10.1016/j.envres.2023.118087 |pmid=38159664 |bibcode=2024ER....24518087P }}</ref> mining,<ref name="EPA2022"/><ref>{{cite journal | title=Respirable nano-particulate generations and their pathogenesis in mining workplaces: a review| year=2021| doi=10.1007/s40789-021-00412-w| last1=Fan| first1=Long| last2=Liu| first2=Shimin| journal=International Journal of Coal Science & Technology| volume=8| issue=2| pages=179–198| bibcode=2021IJCST...8..179F }}</ref><ref name="Rojano">{{cite journal |last1=Rojano |first1=R |last2=Arregocés |first2=HA |last3=Restrepo |first3=G |title=Analysis of PM(10) trends in open-pit mining: Assessing emission controls and WHO guideline compliance. |journal=Heliyon |date=15 February 2025 |volume=11 |issue=3 |article-number=e42277 |doi=10.1016/j.heliyon.2025.e42277 |doi-access=free |pmid=39944335 |pmc=11815905 }}</ref> smelting<ref name="pmid33790361">{{cite journal |vauthors=Jeong H, Choi JY, Ra K |title=Potentially toxic elements pollution in road deposited sediments around the active smelting industry of Korea |journal=Sci Rep |volume=11 |issue=1 |article-number=7238 |date=March 2021 |pmid=33790361 |pmc=8012626 |doi=10.1038/s41598-021-86698-x |bibcode=2021NatSR..11.7238J |url=}}</ref> and oil refining.<ref>{{cite journal |last1=Kim |first1=H |last2=Festa |first2=N |last3=Burrows |first3=K |last4=Kim |first4=DC |last5=Gill |first5=TM |last6=Bell |first6=ML |title=Is residential exposure to oil refineries a novel contextual risk factor for coronary heart disease? |journal=Environmental Research |date=1 March 2024 |volume=244 |article-number=117965 |doi=10.1016/j.envres.2023.117965 |pmid=38123048 |pmc=10928382 |bibcode=2024ER....24417965K }}</ref><ref>{{cite journal |last1=Jindamanee |first1=Kanisorn |last2=Thepanondh |first2=Sarawut |last3=Keawboonchu |first3=Jutarat |last4=Pinthong |first4=Nattaporn |last5=Meeyai |first5=Aronrag |title=Manifesting the hidden pollutants: Quantifying emissions and environmental impact of petroleum refinery on PM2.5 |journal=Atmospheric Environment: X |date=1 December 2024 |volume=24 |article-number=100300 |doi=10.1016/j.aeaoa.2024.100300 |bibcode=2024AtmEX..2400300J |url=https://www.sciencedirect.com/science/article/pii/S2590162124000674 |issn=2590-1621}}</ref><ref>{{cite news| url=https://www.reuters.com/legal/litigation/harmful-soot-unchecked-big-oil-battles-epa-over-testing-2022-01-06/| title=Harmful soot unchecked as Big Oil battles EPA over testing| website=Reuters| date=6 January 2022| last1=McLaughlin| first1=Tim| access-date=14 February 2023| archive-date=14 February 2023| archive-url=https://web.archive.org/web/20230214051338/https://www.reuters.com/legal/litigation/harmful-soot-unchecked-big-oil-battles-epa-over-testing-2022-01-06/| url-status=live}}</ref> * Wet cooling towers in cooling systems.<ref>{{cite journal |last1=Wallis |first1=Christopher D. |last2=Leandro |first2=Mason D. |last3=Chuang |first3=Patrick Y. |last4=Wexler |first4=Anthony S. |title=Positive and negative emissions from cooling towers, part 2: Particulate matter |journal=Aerosol Science and Technology |date=4 March 2025 |volume=59 |issue=3 |pages=253–266 |doi=10.1080/02786826.2024.2439527 |bibcode=2025AerST..59..253W |language=en |issn=0278-6826}}</ref> * Exhaust gas from motor vehicles, including diesel exhaust from heavy equipment used in construction, road building, and other industries.<ref name="Non-exhaust"/> * Road dust from unpaved roads<ref>{{cite journal |vauthors=Khan RK, Strand MA |title=Road dust and its effect on human health: a literature review |journal=Epidemiol Health |volume=40 |issue= |article-number=e2018013 |date=2018 |pmid=29642653 |pmc=5968206 |doi=10.4178/epih.e2018013 |url=}}</ref><ref name="EPA2022"/> and from the wearing down of tires, brakes, and paved road surfaces<ref name="Non-exhaust">{{cite book |doi=10.1787/4a4dc6ca-en |title=Non-exhaust Particulate Emissions from Road Transport |year=2020 |publisher=OECD |isbn=978-92-64-88885-2 }}</ref><ref name="Kelly" />. * Microplastics (as a type of airborne PM)<ref name="pmid35228011">{{cite journal |vauthors=Xie Y, Li Y, Feng Y, Cheng W, Wang Y |title=Inhalable microplastics prevails in air: Exploring the size detection limit |journal=Environ Int |volume=162 |issue= |article-number=107151 |date=April 2022 |pmid=35228011 |doi=10.1016/j.envint.2022.107151 |bibcode=2022EnInt.16207151X |url=}}</ref><ref name="pmid31039519">{{cite journal |vauthors=Liu C, Li J, Zhang Y, Wang L, Deng J, Gao Y, Yu L, Zhang J, Sun H |title=Widespread distribution of PET and PC microplastics in dust in urban China and their estimated human exposure |journal=Environ Int |volume=128 |issue= |pages=116–124 |date=July 2019 |pmid=31039519 |doi=10.1016/j.envint.2019.04.024 |bibcode=2019EnInt.128..116L |url=}}</ref><ref name="Yuk">{{cite journal | last1=Yuk | first1=Hyeonseong | last2=Jo | first2=Ho Hyeon | last3=Nam | first3=Jihee | last4=Kim | first4=Young Uk | last5=Kim | first5=Sumin | title=Microplastic: A particulate matter(PM) generated by deterioration of building materials | journal=Journal of Hazardous Materials | publisher=Elsevier BV | volume=437 | year=2022 | doi=10.1016/j.jhazmat.2022.129290 | article-number=129290| pmid=35753297 | bibcode=2022JHzM..43729290Y }}</ref> of which vehicle-related microplastics from road and tire wear are a major part.<ref name="Siegfried">{{cite journal |last1=Siegfried |first1=Max |last2=Koelmans |first2=Albert A. |last3=Besseling |first3=Ellen |last4=Kroeze |first4=Carolien |title=Export of microplastics from land to sea. A modelling approach |journal=Water Research |date=15 December 2017 |volume=127 |pages=249–257 |doi=10.1016/j.watres.2017.10.011 |pmid=29059612 |bibcode=2017WatRe.127..249S |url=https://www.sciencedirect.com/science/article/pii/S0043135417308400 |issn=0043-1354}}</ref><ref name="Kaushik">{{cite journal |last1=Kaushik |first1=Ankush |last2=Peter |first2=Anju Elizbath |last3=van Pinxteren |first3=Manuela |last4=Scholz-Böttcher |first4=Barbara M. |last5=Herrmann |first5=Hartmut |title=Composition, interactions and resulting inhalation risk of micro- and nano-plastics in urban air |journal=Communications Earth & Environment |date=1 December 2025 |volume=6 |issue=1 |page=985 |doi=10.1038/s43247-025-02980-0 |bibcode=2025ComEE...6..985K |url=https://www.nature.com/articles/s43247-025-02980-0 |language=en |issn=2662-4435}}</ref><ref name="Miner">{{cite journal |last1=Miner |first1=Patrick |last2=Smith |first2=Barbara M. |last3=Jani |first3=Anant |last4=McNeill |first4=Geraldine |last5=Gathorne-Hardy |first5=Alfred |title=Car harm: A global review of automobility's harm to people and the environment |journal=Journal of Transport Geography |date=1 February 2024 |volume=115 |article-number=103817 |doi=10.1016/j.jtrangeo.2024.103817 |bibcode=2024JTGeo.11503817M |url=https://www.sciencedirect.com/science/article/pii/S0966692324000267 |issn=0966-6923}}</ref><ref name="Sarkar">{{cite journal |last1=Sarkar |first1=S |last2=Diab |first2=H |last3=Thompson |first3=J |title=Microplastic Pollution: Chemical Characterization and Impact on Wildlife. |journal=International Journal of Environmental Research and Public Health |date=18 January 2023 |volume=20 |issue=3 |page=1745 |doi=10.3390/ijerph20031745 |doi-access=free |pmid=36767120 |pmc=9914693 }}</ref> * Agricultural activities (e.g. wind erosion,<ref>{{cite journal |last1=Zhang |first1=H |last2=Wang |first2=F |last3=Zhou |first3=S |last4=Zhang |first4=T |last5=Qi |first5=M |last6=Song |first6=H |title=Contribution of dust emissions from farmland to particulate matter concentrations in North China Plain: Integration of WRF-Chem and WEPS model. |journal=Environment International |date=January 2025 |volume=195 |article-number=109191 |doi=10.1016/j.envint.2024.109191 |pmid=39673873 |bibcode=2025EnInt.19509191Z }}</ref> ploughing, soil tilling, grain harvesting, and livestock management).<ref name="EPA2022"/><ref name="Domingo">{{cite journal |last1=Domingo |first1=NGG |last2=Balasubramanian |first2=S |last3=Thakrar |first3=SK |last4=Clark |first4=MA |last5=Adams |first5=PJ |last6=Marshall |first6=JD |last7=Muller |first7=NZ |last8=Pandis |first8=SN |last9=Polasky |first9=S |last10=Robinson |first10=AL |last11=Tessum |first11=CW |last12=Tilman |first12=D |last13=Tschofen |first13=P |last14=Hill |first14=JD |title=Air quality-related health damages of food. |journal=Proceedings of the National Academy of Sciences of the United States of America |date=18 May 2021 |volume=118 |issue=20 |article-number=e2013637118 |doi=10.1073/pnas.2013637118 |doi-access=free |pmid=33972419 |pmc=8158015 |bibcode=2021PNAS..11813637D }}</ref><ref>{{cite journal |last1=Wyer |first1=KE |last2=Kelleghan |first2=DB |last3=Blanes-Vidal |first3=V |last4=Schauberger |first4=G |last5=Curran |first5=TP |title=Ammonia emissions from agriculture and their contribution to fine particulate matter: A review of implications for human health. |journal=Journal of Environmental Management |date=1 December 2022 |volume=323 |article-number=116285 |doi=10.1016/j.jenvman.2022.116285 |pmid=36261990 |bibcode=2022JEnvM.32316285W }}</ref> * Cooking (frying, boiling, grilling).<ref>{{Cite journal |last1=Patel |first1=Sameer |last2=Sankhyan |first2=Sumit |last3=Boedicker |first3=Erin K. |last4=DeCarlo |first4=Peter F. |last5=Farmer |first5=Delphine K. |last6=Goldstein |first6=Allen H. |last7=Katz |first7=Erin F. |last8=Nazaroff |first8=William W |last9=Tian |first9=Yilin |last10=Vanhanen |first10=Joonas |last11=Vance |first11=Marina E. |date=16 June 2020 |title=Indoor Particulate Matter during HOMEChem: Concentrations, Size Distributions, and Exposures |journal=Environmental Science & Technology |language=en |volume=54 |issue=12 |pages=7107–7116 |bibcode=2020EnST...54.7107P |doi=10.1021/acs.est.0c00740 |pmid=32391692 }}</ref><ref name=":6" /><ref name="Yun" /><ref>{{cite journal |title=Outdoor charcoal grilling: Particulate and gas-phase emissions, organic speciation and ecotoxicological assessment |journal=Atmospheric Environment |date=September 2022 |volume=285 |article-number=119240 |doi=10.1016/j.atmosenv.2022.119240 |bibcode=2022AtmEn.28519240A |vauthors=Alves CA, Evtyugina M, Vicente E, Vicente A, Gonçalves C, Neto AI, Nunes T, Kováts N|doi-access=free}}</ref><ref>{{cite journal |vauthors=Jelonek Z, Drobniak A, Mastalerz M, Jelonek I |title=Environmental implications of the quality of charcoal briquettes and lump charcoal used for grilling |journal=Sci Total Environ |volume=747 |issue= |article-number=141267 |date=December 2020 |pmid=32777507 |doi=10.1016/j.scitotenv.2020.141267 |bibcode=2020ScTEn.74741267J }}</ref> * Smoking<ref name="Ma2024">{{cite journal |last1=Ma |first1=Lan |last2=Wen |first2=Zuoying |last3=Gu |first3=Xuejun |last4=Ye |first4=Shaoxin |last5=Ma |first5=Ziji |last6=Zhang |first6=Weijun |last7=Tang |first7=Xiaofeng |title=Ultrafine particles formation from ozonolysis of gas- and particle-phases of cigarette smoke |journal=Atmospheric Environment |date=1 September 2024 |volume=332 |article-number=120628 |doi=10.1016/j.atmosenv.2024.120628 |bibcode=2024AtmEn.33220628M |url=https://www.sciencedirect.com/science/article/abs/pii/S1352231024003030 |issn=1352-2310}}</ref> * Disasters<ref>{{cite book | pmc=7121041| last1=Chandrappa| first1=R.| last2=Chandra Kulshrestha| first2=U.| title=Sustainable Air Pollution Management| chapter=Air Pollution and Disasters| series=Environmental Science and Engineering| date=2016| pages=325–343| doi=10.1007/978-3-319-21596-9_8| isbn=978-3-319-21595-2}}</ref> (e.g. wildfires, which may be human- or naturally-caused,<ref>{{cite journal |last1=Orr |first1=A |last2=Adam |first2=CE |last3=Graham |first3=J |last4=Holden |first4=ZA |last5=Hu |first5=L |last6=Jaffar |first6=Z |last7=Leary |first7=C |last8=Migliaccio |first8=CT |last9=Mullan |first9=K |last10=Noonan |first10=C |last11=Semmens |first11=EO |last12=Urbanski |first12=S |last13=Walker |first13=E |last14=Landguth |first14=EL |title=A State of the Science Review of Wildfire-Specific Fine Particulate Matter Data Sources, Methods, and Models. |journal=Environmental Health Perspectives |date=June 2025 |volume=133 |issue=6 |page=66001 |doi=10.1289/EHP15672 |pmid=40324008 |pmc=12156208 |bibcode=2025EnvHP.133f6001O }}</ref><ref>{{cite journal |last1=Burke |first1=M |last2=Childs |first2=ML |last3=de la Cuesta |first3=B |last4=Qiu |first4=M |last5=Li |first5=J |last6=Gould |first6=CF |last7=Heft-Neal |first7=S |last8=Wara |first8=M |title=The contribution of wildfire to PM(2.5) trends in the USA. |journal=Nature |date=October 2023 |volume=622 |issue=7984 |pages=761–766 |doi=10.1038/s41586-023-06522-6 |pmid=37730996}}</ref> wars,<ref name="Levy">{{cite journal |last1=Levy |first1=BS |title=The impacts of war on health, human rights, and the environment-an overview. |journal=Frontiers in Public Health |date=2025 |volume=13 |article-number=1547784 |doi=10.3389/fpubh.2025.1547784 |doi-access=free|pmid=41041369 |pmc=12484150 |bibcode=2025FrPH...1347784L }}</ref><ref>{{cite web | url=https://www.publichealth.va.gov/exposures/sand-dust-particulates/index.asp | title=Sand, Dust and Particulates Public Health |website=U.S. Department of Veteran's Affairs}}</ref><ref>{{cite journal | title=War Impact on Air Quality in Ukraine| year=2022| doi=10.3390/su142113832| doi-access=free| last1=Zalakeviciute| first1=Rasa| last2=Mejia| first2=Danilo| last3=Alvarez| first3=Hermel| last4=Bermeo| first4=Xavier| last5=Bonilla-Bedoya| first5=Santiago| last6=Rybarczyk| first6=Yves| last7=Lamb| first7=Brian| journal=Sustainability| volume=14| issue=21| article-number=13832| bibcode=2022Sust...1413832Z}}</ref> and the 11 September attacks.)<ref>{{cite journal |last1=Mears |first1=MJ |last2=Aslaner |first2=DM |last3=Barson |first3=CT |last4=Cohen |first4=MD |last5=Gorr |first5=MW |last6=Wold |first6=LE |title=Health effects following exposure to dust from the World Trade Center disaster: An update. |journal=Life Sciences |date=15 January 2022 |volume=289 |article-number=120147 |doi=10.1016/j.lfs.2021.120147 |pmid=34785191 |pmc=8791014 }}</ref>

=== Worldwide and seasonal sources === Human-generated particulates are often smaller in size (e.g. PM2.5 or PM1), and pose significant threats to human health.<ref name="Shaffer">{{cite news |last1=Shaffer |first1=Leah |title=Tiny and toxic: Researchers track smaller air pollution particles across US skies |url=https://source.washu.edu/2025/06/tiny-and-toxic-researchers-track-smaller-air-pollution-particles-across-us-skies/ |work=The Source |date=16 June 2025}}</ref><ref name="Li40516540"/> Globally, major contributors to PM2.5 include residential energy use (40%), industrial processes (11.7%), and energy generation (10.2%), all of which involve fuel combustion.<ref name="McDuffie"/>

The types of emissions that contribute to particulate matter vary widely across countries and local regions, reflecting regional characteristics, seasonal variation, human activities, and types of fuels used. A worldwide analysis in 2021 reported that of anthropogenic fuels, coal was the highest contributor to PM2.5-related mortality in China; oil and natural gas dominated in Egypt, Russia, and the United States; and solid biofuels had the highest impact in Pakistan, Bangladesh, Indonesia, India, and Nigeria. Contributions due to residential fuel use varied from 4.0% in Egypt to 33.1% in Indonesia. Contributions from energy and industry sectors ranged from 3.2% in Nigeria to 27.3% in India. The most common PM2.5-related causes of death were ischemic heart disease (IHD) and stroke. The impact of windblown dust ranged from 1.5% in Bangladesh to 70.6% in Nigeria, where lower respiratory tract infections (LRIs) in childhood were the largest PM2.5-related cause of mortality. <ref name="McDuffie">{{cite journal |last1=McDuffie |first1=EE |last2=Martin |first2=RV |last3=Spadaro |first3=JV |last4=Burnett |first4=R |last5=Smith |first5=SJ |last6=O'Rourke |first6=P |last7=Hammer |first7=MS |last8=van Donkelaar |first8=A |last9=Bindle |first9=L |last10=Shah |first10=V |last11=Jaeglé |first11=L |last12=Luo |first12=G |last13=Yu |first13=F |last14=Adeniran |first14=JA |last15=Lin |first15=J |last16=Brauer |first16=M |title=Source sector and fuel contributions to ambient PM(2.5) and attributable mortality across multiple spatial scales. |journal=Nature Communications |date=14 June 2021 |volume=12 |issue=1 |page=3594 |doi=10.1038/s41467-021-23853-y |pmid=34127654 |pmc=8203641 }}</ref>

An examination of PM2.5 concentrations using data from 2000–2019 showed that during those two decades, PM2.5 concentrations in Europe and northern America decreased,<ref name="Yu2023" /> due to reductions in fossil fuel emissions.<ref name="McDuffie" /> However, exposures increased in southern Asia, Australia, New Zealand, Latin America and the Caribbean. Distinct seasonal patterns were seen in many parts of the world. There were regular high regional PM2.5 concentrations in the Amazon rainforest in August and September. Sub-Saharan Africa showed higher levels from June to September. Levels in eastern North America were higher in their summer months. Levels in China and north India were high in their winter months,<ref name="Yu2023">{{cite journal |last1=Yu |first1=Wenhua |last2=Ye |first2=Tingting |last3=Zhang |first3=Yiwen |last4=Xu |first4=Rongbin |last5=Lei |first5=Yadong |last6=Chen |first6=Zhuying |last7=Yang |first7=Zhengyu |last8=Zhang |first8=Yuxi |last9=Song |first9=Jiangning |last10=Yue |first10=Xu |last11=Li |first11=Shanshan |last12=Guo |first12=Yuming |title=Global estimates of daily ambient fine particulate matter concentrations and unequal spatiotemporal distribution of population exposure: a machine learning modelling study |journal=The Lancet Planetary Health |date=1 March 2023 |volume=7 |issue=3 |pages=e209–e218 |doi=10.1016/S2542-5196(23)00008-6 |pmid=36889862 |url=https://www.thelancet.com/journals/lanplh/article/piis2542-5196(23)00008-6/fulltext |language=English |issn=2542-5196}}</ref><ref>{{cite journal |last1=Jia |first1=Zixuan |last2=Doherty |first2=Ruth M. |last3=Ordóñez |first3=Carlos |last4=Li |first4=Chaofan |last5=Wild |first5=Oliver |last6=Jain |first6=Shipra |last7=Tang |first7=Xiao |title=The impact of large-scale circulation on daily fine particulate matter (PM2.5) over major populated regions of China in winter |journal=Atmospheric Chemistry and Physics |date=19 May 2022 |volume=22 |issue=10 |pages=6471–6487 |doi=10.5194/acp-22-6471-2022 |doi-access=free |url=https://acp.copernicus.org/articles/22/6471/2022/ |language=English |issn=1680-7316}}</ref> as are levels in South Korea.<ref name="Jeong">{{cite journal |last1=Jeong |first1=Yong-Cheol |last2=Yeh |first2=Sang-Wook |last3=Jeong |first3=Jaein I. |last4=Park |first4=Rokjin J. |last5=Yoo |first5=Changhyun |last6=Yoon |first6=Jin-Ho |title=Intrinsic atmospheric circulation patterns associated with high PM2.5 concentration days in South Korea during the cold season |journal=Science of the Total Environment |date=10 March 2023 |volume=863 |article-number=160878 |doi=10.1016/j.scitotenv.2022.160878 |pmid=36516924 |url=https://www.sciencedirect.com/science/article/abs/pii/S0048969722079815 |issn=0048-9697}}</ref><ref>{{cite journal |last1=Lee |first1=Su Jeong |last2=Lee |first2=Sang-Hyun |last3=Choi |first3=Hyung-Jin |last4=Kim |first4=Joowan |last5=Kim |first5=Maeng-Ki |title=Influence of Local Circulation on Short-term Variations in Ground-level PM2.5 Concentrations |journal=Aerosol and Air Quality Research |date=2024 |volume=24 |issue=10 |article-number=240042 |doi=10.4209/aaqr.240042 |bibcode=2024AAQR...24x0042L |url=https://aaqr.org/articles/aaqr-24-02-oa-0042 |language=en |issn=2071-1409}}</ref>

===Domestic combustion=== {{See also|Household air pollution|Energy poverty and cooking}} As of 2023, more than 2.3 billion people worldwide, many of them in developing countries, burn polluting biomass fuels such as wood, dry dung, coal, or kerosene for cooking or heating. This causes harmful household air pollution and contributes significantly to outdoor air pollution. Cooking-related pollution was estimated to cause 3.7 million annual deaths.<ref>{{Cite web |title=Executive summary – A Vision for Clean Cooking Access for All – Analysis |url=https://www.iea.org/reports/a-vision-for-clean-cooking-access-for-all/executive-summary |date=2023|access-date=2025-01-09 |website=International Energy Agency (IEA) |language=en-GB}}</ref>

Burning biomass emits large amounts of pollutants including PM{{sub|2.5}} and PM{{sub|10}}, black and brown carbon, carbon monoxide, nitrogen oxides (NOx), sulfur dioxide and ozone.<ref name="who-9789240034228" /><ref name="Eriksson2022" /> The chemical composition of the emitted PM is different for different types of biomass fuels. Less energy dense fuels, such as dung, generate more PM{{sub|2.5}}. Dung and wood yield higher organic aerosol emissions, while dung emits more nitrogen content than other biomass fuels.<ref name="Eriksson2022"/><ref>{{cite journal |last1=Li |first1=Jing |last2=Fan |first2=Guangtao |last3=Ou |first3=Yinping |last4=Deng |first4=Qihong |title=Characteristics and control strategies of indoor particles: An updated review |journal=Energy and Buildings |date=1 September 2023 |volume=294 |article-number=113232 |doi=10.1016/j.enbuild.2023.113232 |bibcode=2023EneBu.29413232L |url=https://www.sciencedirect.com/science/article/abs/pii/S0378778823004620 |issn=0378-7788}}</ref>

In the United Kingdom domestic combustion is the largest single source of PM{{sub|2.5}} and PM{{sub|10}} annually.<ref name="Stats" /> In 2019, domestic wood burning in both closed stoves and open fires was responsible for 38% of PM{{sub|2.5}} in the UK. Following the introduction of new laws in 2021 that restricted the sale of wet wood and house coal, particulate levels from domestic use decreased.<ref name="Stats" /><ref name="Carrington">{{Cite web|last=Carrington|first=Damian|date=16 February 2021|title=Wood burning at home now biggest cause of UK particle pollution|url=http://www.theguardian.com/environment/2021/feb/16/home-wood-burning-biggest-cause-particle-pollution-fires|access-date=13 February 2022|website=The Guardian|language=en|archive-date=27 December 2022|archive-url=https://web.archive.org/web/20221227162919/https://www.theguardian.com/environment/2021/feb/16/home-wood-burning-biggest-cause-particle-pollution-fires|url-status=live}}</ref> During 2024, domestic wood burning was responsible for 20% of PM{{sub|2.5}} and 11% of PM{{sub|10}} in the UK.<ref name="Stats">{{Cite web|url=https://www.gov.uk/government/statistics/emissions-of-air-pollutants/emissions-of-air-pollutants-in-the-uk-particulate-matter-pm10-and-pm25#trends-in-total-annual-emissions-of-pm10-and-pm25-in-the-uk-1990-to-2023|title=Emissions of air pollutants in the UK – Particulate matter (PM10 and PM2.5)|website=GOV.UK |date=12 February 2026}}</ref> During the winter months, the impact of wood burning is higher and can contribute to half of PM{{sub|2.5}} concentrations.<ref>{{Cite web |last=Brierley |first=Louise |date=2024-12-10 |title=Air pollution: Wood burners more polluting than traffic - Birmingham research |url=https://www.bbc.com/news/articles/cjdne9ke0m1o |access-date=2026-03-24 |website=www.bbc.com |language=en-GB}}</ref>

Given the health effects of wood smoke, it is recommended that people only use wood burners or fireplaces if they had no other source of heat.<ref name="Carrington"/> If a stove or open fire is used, the release of particulates may be reduced by using an improved closed wood-burning stove of appropriate size for the space to be heated, maintaining the stove properly, using seasoned wood or kiln-dried wood, and managing the fire appropriately.<ref name="Kuye">{{cite journal |last1=Kuye |first1=A |last2=Kumar |first2=P |title=Particulate matter exposure from different heating stoves and fuels in UK homes. |journal=Scientific Reports |date=1 July 2025 |volume=15 |issue=1 |page=21394 |doi=10.1038/s41598-025-05886-1 |pmid=40594781 |pmc=12217894 |bibcode=2025NatSR..1521394K }}</ref><ref>{{cite journal |last1=Rahman |first1=M |last2=Petersen |first2=H |last3=Irshad |first3=H |last4=Liu |first4=C |last5=McDonald |first5=J |last6=Sood |first6=A |last7=Meek |first7=PM |last8=Tesfaigzi |first8=Y |title=Cleaning the Flue in Wood-Burning Stoves Is a Key Factor in Reducing Household Air Pollution. |journal=Toxics |date=17 October 2022 |volume=10 |issue=10 |page=615 |doi=10.3390/toxics10100615 |doi-access=free|pmid=36287895 |pmc=9609584 |bibcode=2022Toxic..10..615R }}</ref><ref>{{cite web |title=How to use your wood fired heater the right way |url=https://www.epa.vic.gov.au/media/989009 |website=State Government of Victoria |access-date=24 March 2026 |language=en-au |date=2 December 2024}}</ref><ref>{{cite web |title=Focus on Cleaner Wood Burning |url=https://apps.ecology.wa.gov/publications/documents/91br022.pdf |website=Department of the Environment, State of Washington, USA |access-date=24 March 2026}}</ref><ref>{{cite web |title=Residential Wood Burning |url=https://www.lung.org/clean-air/indoor-air/indoor-air-pollutants/residential-wood-burning |website=American Lung Association |access-date=24 March 2026 |language=en}}</ref> When cooking, use of improved cooking stoves and better quality fuels may help to reduce particulate exposure.<ref name="Adhikari">{{cite journal |last1=Adhikari |first1=Bipin |last2=Kang |first2=Sophie Suh Young |last3=Dahal |first3=Aaryan |last4=Mshamu |first4=Salum |last5=Deen |first5=Jacqueline |last6=Pell |first6=Christopher |last7=Seidlein |first7=Lorenz von |last8=Knudsen |first8=Jakob |last9=Bøjstrup |first9=Thomas Chevalier |title=Acceptability of improved cook stoves-a scoping review of the literature |journal=PLOS Global Public Health |date=7 January 2025 |volume=5 |issue=1 |article-number=e0004042 |doi=10.1371/journal.pgph.0004042 |doi-access=free|pmid=39775247 |pmc=11706475 |language=en |issn=2767-3375}}</ref>

=== Waste combustion === Composition of particles can vary greatly depending on their sources and production. Particles emitted from fuel combustion are not the same as those emitted from waste combustion. Particulates emitted from the burning of vegetation, incense paper, construction waste, and plastics will all differ. Particulate matter from a fire in a recycling yard<ref>{{cite web| url=https://www.wdtn.com/news/local-news/the-dangers-of-a-scrap-yard-fire-in-your-community/amp/| author-first=Cameron |author-last=Saliga |title=The dangers of a scrap yard fire in your community| website=WDTN News |date=10 October 2022| access-date=16 February 2023| archive-date=16 February 2023| archive-url=https://web.archive.org/web/20230216125000/https://www.wdtn.com/news/local-news/the-dangers-of-a-scrap-yard-fire-in-your-community/amp/| url-status=live}}</ref> or a ship full of scrap metal<ref>{{cite web | url=https://www.scmp.com/news/hong-kong/society/article/3135821/hong-kong-barge-fire-sends-cloud-acrid-smoke-sweeping-across | author-first1=Danny | author-last1=Mok | author-first2=Clifford | author-last2=Lo| title=Cargo boat fire put out in Hong Kong's Victoria Harbour after burning for 15 hours and sending fumes across city| date=3 June 2021 |work=South China Morning Post}}</ref><ref>{{Cite web | url=https://www.thestandard.com.hk/section-news/section/11/230923/Stench-from-burning-metal-waste-ship-blows-across-HK |date=2021 | title=Stench from burning metal-waste ship blows across HK | work= The Standard |location=Hong Kong | access-date=16 February 2023 | archive-date=16 February 2023 | archive-url=https://web.archive.org/web/20230216124955/https://www.thestandard.com.hk/section-news/section/11/230923/Stench-from-burning-metal-waste-ship-blows-across-HK | url-status=live }}</ref> may contain more toxic substances than other types of burning.<ref name="O'Mara">{{cite news |last1=O'Mara |first1=Kelly |title=Smelly Smoke From Oakland Metal Recycler Fire Prompts Health Concerns {{!}} KQED |url=https://www.kqed.org/news/11957894/smelly-smoke-from-oakland-metal-recycler-fire-prompts-health-concerns |access-date=16 April 2026 |work=www.kqed.org |date=10 August 2023 |language=en}}</ref>

=== Construction === Different types of building activities produce different kinds of dust, that can have different effects on health. The composition of PM generated from cutting or mixing concrete made with Portland Cement would be different from those generated from cutting or mixing concrete made with different types of slag (e.g. GGBFS, EAF slag<ref>{{cite web |url=https://www.epa.gov/smm/electric-arc-furnace-eaf-slag |title=Electric Arc Furnace (EAF) Slag|date=3 June 2021 }}</ref>), fly ash or even EAF dust (EAFD),<ref>{{cite journal |last1=Nair |first1=Abhilash T. |last2=Mathew |first2=Aneesh |last3=A R |first3=Archana |last4=Akbar |first4=M Abdul |title=Use of hazardous electric arc furnace dust in the construction industry: A cleaner production approach |journal=Journal of Cleaner Production |date=December 2022 |volume=377 |article-number=134282 |doi=10.1016/j.jclepro.2022.134282 |bibcode=2022JCPro.37734282N }}</ref> while EFAD, slag and fly ash are likely to be more toxic as they contain heavy metals. Besides slag cement that is sold and used as an environmental friendly product,<ref>{{cite web | url=https://www.slagcement.org/sustainability | title=Sustainability | access-date=20 March 2023 | archive-date=20 March 2023 | archive-url=https://web.archive.org/web/20230320140318/https://www.slagcement.org/sustainability | url-status=live }}</ref><ref>{{cite web |url=https://www.epd.gov.hk/epd/english/how_help/tools_epr/files/hd_er2012e.pdf |title=Hong Kong Housing Authority Sustainability Report 2012/13|archive-url=https://web.archive.org/web/20230628093414/https://www.epd.gov.hk/epd/english/how_help/tools_epr/files/hd_er2012e.pdf |archive-date=28 June 2023 }}</ref><ref>{{cite web |url=https://www.housingauthority.gov.hk/mini-site/haer2021/en/environmental-performance-planning.html |title=Hong Kong Housing Authority – Environmental Report 2020/21|archive-url=https://web.archive.org/web/20230628093525/https://www.housingauthority.gov.hk/mini-site/haer2021/en/environmental-performance-planning.html |archive-date=28 June 2023 }}</ref> fake (adulterated) cement, where different types of slag, fly ash or other unknown substances are added, is also very common in some places<ref>{{cite web | url=https://www.globalcement.com/news/itemlist/tag/Fake | title=Cement industry news from Global Cement| archive-url=https://web.archive.org/web/20221203120609/https://www.globalcement.com/news/itemlist/tag/Fake| archive-date=3 December 2022}}</ref><ref>{{cite web | url=https://hunan-sina-com-cn.translate.goog/city/gdyw/2013-12-16/110281337.html?_x_tr_sl=zh-CN&_x_tr_tl=en | title=黑水泥厂"围城" 打假队一年揪出13家 | trans-title=City "besieged" with dishonest cement factories, anti-counterfeiting teams found 13 of them in one year | language=Chinese | access-date=20 March 2023 | archive-date=20 March 2023 | archive-url=https://web.archive.org/web/20230320161844/https://hunan-sina-com-cn.translate.goog/city/gdyw/2013-12-16/110281337.html?_x_tr_sl=zh-CN&_x_tr_tl=en | url-status=live }}</ref> due to the much lower production cost.<ref>{{Cite web| url=https://gunungcapital.com/growing-importance-of-slag-cement-in-the-global-cement-industry/| title=Growing Importance of Slag Cement in the Global Cement Industry| work=Gunung Capital| date=6 July 2022| access-date=20 March 2023| archive-date=20 March 2023| archive-url=https://web.archive.org/web/20230320141823/https://gunungcapital.com/growing-importance-of-slag-cement-in-the-global-cement-industry/| url-status=live}}</ref> To address quality<ref>{{cite web | url=https://tw-yahoo-com.translate.goog/house/%E6%88%BF%E5%B8%82%E6%96%B0%E5%88%B6%E5%A4%A7%E8%AA%BF%E6%9F%A5%E7%88%90%E6%B8%A3%E5%B1%8B%E6%8E%B0-2021-%E5%B9%B4%E8%B5%B7%E7%A6%81%E7%94%A8%E7%88%90%E6%B8%A3-062821875.html?_x_tr_sl=auto&_x_tr_tl=en | title=房市新制大調查爐渣屋掰 2021年起禁用爐渣 | date=10 December 2020 | trans-title=A look into the property market new regulations. No more slag house. Slag will be banned from 2021 | language=Chinese}}</ref> and toxicity problems, some places are starting to ban the use of EAF slag in cement used in buildings.<ref>{{cite web | url=https://tw-news-yahoo-com.translate.goog/%E6%96%B0%E7%89%88%E9%A0%90%E5%94%AE%E5%B1%8B%E5%A5%91%E7%B4%84%E7%A6%81%E7%94%A8-%E7%85%89%E9%8B%BC%E7%88%90%E7%A2%B4-%E5%BB%BA%E5%95%86%E9%81%95%E8%A6%8F%E5%B0%87%E6%8C%A8%E7%BD%B0-180847768.html?_x_tr_sl=auto&_x_tr_tl=en | title=新版預售屋契約禁用「煉鋼爐碴」建商違規將挨罰 | work=Yahoo News | date=8 May 2019 | trans-title=The new version of the pre-sale house contract prohibits "steelmaking furnace slag" and builders will be fined for violations | language=Chinese | access-date=20 March 2023 | archive-date=20 March 2023 | archive-url=https://web.archive.org/web/20230320143630/https://tw-news-yahoo-com.translate.goog/%E6%96%B0%E7%89%88%E9%A0%90%E5%94%AE%E5%B1%8B%E5%A5%91%E7%B4%84%E7%A6%81%E7%94%A8-%E7%85%89%E9%8B%BC%E7%88%90%E7%A2%B4-%E5%BB%BA%E5%95%86%E9%81%95%E8%A6%8F%E5%B0%87%E6%8C%A8%E7%BD%B0-180847768.html?_x_tr_sl=auto&_x_tr_tl=en | url-status=live }}</ref>

Composition of welding fumes varies and it depends on the metals in the material being welded and the composition of the coatings, electrode, etc. being used.<ref>{{cite web |url=https://www.ccohs.ca/oshanswers/safety_haz/welding/fumes.html |title=Welding – Fumes And Gases, OSH Answers |date=10 February 2023 |access-date=6 February 2023 |archive-date=24 January 2023 |archive-url=https://web.archive.org/web/20230124230808/https://www.ccohs.ca/oshanswers/safety_haz/welding/fumes.html |url-status=live }}</ref>

Since construction and refurbishment projects are prominent sources of particulate matter,<ref>{{Cite web | url=http://www32.ha.org.hk/capitalworksprojects/en/Others/Ten-Year-Hospital-Development-Plan.html | title=10-year Hospital Development Plan | access-date=13 February 2023 | archive-date=13 February 2023 | archive-url=https://web.archive.org/web/20230213045203/http://www32.ha.org.hk/capitalworksprojects/en/Others/Ten-Year-Hospital-Development-Plan.html | url-status=live }}</ref><ref>{{Cite web | url=https://www.archsd.gov.hk/en/projects/capital-projects-under-construction.html | title=Architectural Services Department – Capital Projects Under Construction | access-date=13 February 2023 | archive-date=13 February 2023 | archive-url=https://web.archive.org/web/20230213045205/https://www.archsd.gov.hk/en/projects/capital-projects-under-construction.html | url-status=live }}</ref> planning and mitigation measures regarding PM emission should be adopted and carefully monitored, particularly when such projects involve actively used health facilities.

== Composition == thumb|GEOS portrait of global aerosols, August 1-September 14, 2024.<ref name="Ott">{{cite web |last1=Ott |first1=Joseph V. Ardizzone, Helen-Nicole Kostis, and Lesley |title=NASA Scientific Visualization Studio {{!}} GEOS Aerosols |url=https://svs.gsfc.nasa.gov/5572/ |website=NASA Scientific Visualization Studio |access-date=1 April 2026 |language=english |date=8 August 2025}}</ref> {{legend striped|red|orange|Black carbon/Fires (orange/red)}} {{legend striped|#722|#b52|Mineral dust (pink/magenta)}} {{legend|#48b|Sea salt (blue)}} {{legend|green|Sulfates (green)}} {{further|Asian Dust#Composition|Particulate organic matter}}

The chemical composition of particulate matter (PM) in atmospheric aerosols varies widely with both time and space. It is affected by emission sources (both natural- and human-caused), geography, weather conditions, and chemical reactions.<ref name="Drudi" /> Atmospheric aerosols can change between liquid, solid, and semisolid states depending on conditions.<ref>{{cite journal |last1=Su |first1=H |last2=Cheng |first2=Y |last3=Pöschl |first3=U |title=New Multiphase Chemical Processes Influencing Atmospheric Aerosols, Air Quality, and Climate in the Anthropocene. |journal=Accounts of Chemical Research |date=20 October 2020 |volume=53 |issue=10 |pages=2034–2043 |doi=10.1021/acs.accounts.0c00246 |pmid=32927946 |pmc=7581287 }}</ref> The particulate matter in an aerosol can be described as primary (directly emitted) or secondary (formed through chemical reactions in the air).<ref name="Kelly" /> PM can include both organic<ref name="ChenG">{{cite journal |last1=Chen |first1=Gang |last2=Canonaco |first2=Francesco |last3=Tobler |first3=Anna |last4=Aas |first4=Wenche |last5=Alastuey |first5=Andres |last6=Allan |first6=James |last7=Atabakhsh |first7=Samira |last8=Aurela |first8=Minna |last9=Baltensperger |first9=Urs |last10=Bougiatioti |first10=Aikaterini |last11=De Brito |first11=Joel F. |last12=Ceburnis |first12=Darius |last13=Chazeau |first13=Benjamin |last14=Chebaicheb |first14=Hasna |last15=Daellenbach |first15=Kaspar R. |last16=Ehn |first16=Mikael |last17=El Haddad |first17=Imad |last18=Eleftheriadis |first18=Konstantinos |last19=Favez |first19=Olivier |last20=Flentje |first20=Harald |last21=Font |first21=Anna |last22=Fossum |first22=Kirsten |last23=Freney |first23=Evelyn |last24=Gini |first24=Maria |last25=Green |first25=David C |last26=Heikkinen |first26=Liine |last27=Herrmann |first27=Hartmut |last28=Kalogridis |first28=Athina-Cerise |last29=Keernik |first29=Hannes |last30=Lhotka |first30=Radek |last31=Lin |first31=Chunshui |last32=Lunder |first32=Chris |last33=Maasikmets |first33=Marek |last34=Manousakas |first34=Manousos I. |last35=Marchand |first35=Nicolas |last36=Marin |first36=Cristina |last37=Marmureanu |first37=Luminita |last38=Mihalopoulos |first38=Nikolaos |last39=Močnik |first39=Griša |last40=Nęcki |first40=Jaroslaw |last41=O'Dowd |first41=Colin |last42=Ovadnevaite |first42=Jurgita |last43=Peter |first43=Thomas |last44=Petit |first44=Jean-Eudes |last45=Pikridas |first45=Michael |last46=Matthew Platt |first46=Stephen |last47=Pokorná |first47=Petra |last48=Poulain |first48=Laurent |last49=Priestman |first49=Max |last50=Riffault |first50=Véronique |last51=Rinaldi |first51=Matteo |last52=Różański |first52=Kazimierz |last53=Schwarz |first53=Jaroslav |last54=Sciare |first54=Jean |last55=Simon |first55=Leïla |last56=Skiba |first56=Alicja |last57=Slowik |first57=Jay G. |last58=Sosedova |first58=Yulia |last59=Stavroulas |first59=Iasonas |last60=Styszko |first60=Katarzyna |last61=Teinemaa |first61=Erik |last62=Timonen |first62=Hilkka |last63=Tremper |first63=Anja |last64=Vasilescu |first64=Jeni |last65=Via |first65=Marta |last66=Vodička |first66=Petr |last67=Wiedensohler |first67=Alfred |last68=Zografou |first68=Olga |last69=Cruz Minguillón |first69=María |last70=Prévôt |first70=André S. H. |title=European aerosol phenomenology − 8: Harmonised source apportionment of organic aerosol using 22 Year-long ACSM/AMS datasets |journal=Environment International |date=1 August 2022 |volume=166 |article-number=107325 |doi=10.1016/j.envint.2022.107325 |pmid=35716508 |arxiv=2201.00579 |bibcode=2022EnInt.16607325C |url=https://www.sciencedirect.com/science/article/pii/S0160412022002525 |issn=0160-4120}}</ref> and inorganic components such as minerals.<ref name="Drudi">{{cite journal |last1=Drudi |first1=Lia |last2=Giardino |first2=Matteo |last3=Tedone |first3=Marilena |last4=Tiano |first4=Andrea |last5=Janner |first5=Davide |last6=Pognant |first6=Federica |last7=Matera |first7=Francesco |last8=Sacco |first8=Milena |last9=Bardi |first9=Luisella |last10=Bellopede |first10=Rossana |title=An analysis of the PM10 chemical composition and its spatial and seasonal variation in Piedmont (Italy) using Raman spectroscopy |journal=Science of the Total Environment |date=15 November 2024 |volume=951 |article-number=175427 |doi=10.1016/j.scitotenv.2024.175427 |pmid=39128512 |url=https://www.sciencedirect.com/science/article/pii/S0048969724055773 |issn=0048-9697}}</ref>

Both chemical composition and particle size and shape have effects on human health.<ref name="Damiati" /><ref name="Hamanaka" /><ref name=":7" /> Inhalable particles are often classified in terms of size as either coarse (PM{{sub|10}}) with a diameter of 10 micrometers (μm) or less, or fine (PM{{sub|2.5}}) with a diameter of 2.5 μm or less.<ref name="US EPA" /> Smaller particulates can penetrate deeper into the lungs and travel through the blood stream to reach other organs.<ref name="Błaszczak" /><ref name="Kelly" /><ref name="Gimeno" /> Human-generated particulates are often smaller in size (e.g. PM2.5 or PM1), and pose significant threats to human health.<ref name="Shaffer" /><ref name="Li40516540" />

The chemical composition and size of particulates in an aerosol also determine how the aerosol interacts with solar radiation and affects climate.<ref name="Manavi" /> Chemical constituents within an aerosol change its overall refractive index, determining how much light is scattered or absorbed.<ref>{{cite journal |last1=Li |first1=Yaowei |last2=Bai |first2=Bin |last3=Dykema |first3=John |last4=Shin |first4=Nara |last5=Lambe |first5=Andrew T. |last6=Chen |first6=Qi |last7=Kuwata |first7=Mikinori |last8=Ng |first8=Nga Lee |last9=Keutsch |first9=Frank N. |last10=Liu |first10=Pengfei |title=Predicting Real Refractive Index of Organic Aerosols From Elemental Composition |journal=Geophysical Research Letters |date=28 June 2023 |volume=50 |issue=12 |article-number=e2023GL103446 |doi=10.1029/2023GL103446 |bibcode=2023GeoRL..5003446L |language=en |issn=0094-8276}}</ref>

=== Mineral dust === thumb|right|NASA's Earth Surface Mineral Dust Source Investigation (EMIT) map of global mineral dust sources, 2022<ref>{{cite web |title=NASA Sensor Produces First Global Maps of Surface Minerals in Arid Regions - NASA |url=https://www.nasa.gov/missions/station/iss-research/emit/nasa-sensor-produces-first-global-maps-of-surface-minerals-in-arid-regions/ |website=NASA |access-date=1 April 2026 |date=11 December 2023}}</ref> Wind-blown mineral dust is a major component of particulate matter globally. Most sand and dust storms originate from a dust belt stretching from north Africa through the Middle East into Asia.<ref name="Li2025" /><ref name="Shetty" /> Dust storms can also arise in arid areas of North and South America and Australia.<ref>{{cite web |title=Dust Storms and Haboobs |url=https://www.weather.gov/safety/wind-dust-storm |website=NOAA |publisher=US Department of Commerce |access-date=1 April 2026 |language=EN-US}}</ref><ref>{{cite news |title=Desert Winds Blow Dust Plume Over Southwestern Argentina |url=https://www.nesdis.noaa.gov/news/desert-winds-blow-dust-plume-over-southwestern-argentina |access-date=1 April 2026 |work=National Environmental Satellite, Data, and Information Service |date=1 April 2026 |language=en}}</ref><ref>{{cite news |author-first=Steve |author-last=Turton |title=Australian skies turned blood red. A weather expert explains how |url=https://www.the-independent.com/news/world/australasia/australia-blood-red-sky-cyclone-narelle-b2949130.html |access-date=1 April 2026 |work=The Independent |date=31 March 2026 |language=en}}</ref> Particles from dust storms can remain in the atmosphere and travel thousands of km from their source.<ref name="Li2025">{{cite journal |last1=Li |first1=T |last2=Cohen |first2=AJ |last3=Krzyzanowski |first3=M |last4=Zhang |first4=C |last5=Gumy |first5=S |last6=Mudu |first6=P |last7=Pant |first7=P |last8=Liu |first8=Q |last9=Kan |first9=H |last10=Tong |first10=S |last11=Chen |first11=S |last12=Kang |first12=U |last13=Basart |first13=S |last14=Touré |first14=NE |last15=Al-Hemoud |first15=A |last16=Rudich |first16=Y |last17=Tobias |first17=A |last18=Querol |first18=X |last19=Khomsi |first19=K |last20=Samara |first20=F |last21=Hashizume |first21=M |last22=Stafoggia |first22=M |last23=Malkawi |first23=M |last24=Wang |first24=S |last25=Zhou |first25=M |last26=Shi |first26=X |last27=Jiang |first27=G |last28=Shen |first28=H |title=Sand and dust storms: a growing global health threat calls for international health studies to support policy action. |journal=The Lancet. Planetary Health |date=January 2025 |volume=9 |issue=1 |pages=e34–e40 |doi=10.1016/S2542-5196(24)00308-5 |pmid=39855230 |pmc=11755727 }}</ref><ref name="Shetty">{{cite web |last1=Shetty |first1=Disha |title=Sand And Dust Storms Are Taking A Rising Toll On Health And Economies - Health Policy Watch |url=https://healthpolicy-watch.news/sand-and-dust-storms-are-taking-a-rising-toll-on-health-and-economies-world-metereological-organization/ |website=Health Policy Watch |access-date=1 April 2026 |date=14 July 2025}}</ref>

Mineral dust is a complex mixture that can be formed from quartz, feldspars, clays, calcites, iron oxides and other material blown from the Earth's crust. It often contains mineral oxides of major crustal elements such as aluminum (Al), silicon (Si), calcium (Ca), iron (Fe), and titanium (Ti). It can also contain alkali metals such as potassium (K), sodium (Na),<ref name="Liu">{{cite journal |last1=Liu |first1=X |last2=Turner |first2=JR |last3=Hand |first3=JL |last4=Schichtel |first4=BA |last5=Martin |first5=RV |title=A Global-Scale Mineral Dust Equation |journal=Journal of Geophysical Research: Atmospheres |date=27 September 2022 |volume=127 |issue=18 |article-number=e2022JD036937 |doi=10.1029/2022JD036937 |pmid=36591339 |pmc=9787586 |bibcode=2022JGRD..12736937L }}</ref><ref name="Drudi" /> and lithium (Li);<ref name="Elsayed" /> alkaline earth metals such as magnesium (Mg);<ref name="Drudi" /> and heavy metals such as lead (Pb), copper (Cu), nickel (Ni), and zinc (Zn).<ref name="Elsayed">{{cite journal |last1=Elsayed |first1=Yehya |last2=Kanan |first2=Sofian |last3=Farhat |first3=Ahmad |title=Meteorological patterns, technical validation, and chemical comparison of atmospheric dust depositions and bulk sand in the Arabian Gulf region |journal=Environmental Pollution |date=15 January 2021 |volume=269 |article-number=116190 |doi=10.1016/j.envpol.2020.116190 |pmid=33316506 |bibcode=2021EPoll.26916190E |url=https://www.sciencedirect.com/science/article/abs/pii/S0269749120368792 |issn=0269-7491}}</ref> Mineral dust in particulate matter is light-absorbing.<ref name="Guan">{{cite journal |last1=Guan |first1=Xu |last2=Meng |first2=Siyu |last3=Tian |first3=Pengfei |last4=Wang |first4=Wenfang |last5=Cui |first5=Chen |last6=Ren |first6=Zhuoyue |last7=Wang |first7=Min |last8=Yang |first8=Shengli |last9=Zhang |first9=Lei |title=Distinct Roles of Industrial and Natural Mineral Dust in Aerosol Spectral Absorption in a Semi-Arid Industrial City |journal=Environmental Science & Technology |date=24 March 2026 |volume=60 |issue=18 |article-number=acs.est.5c17112 |doi=10.1021/acs.est.5c17112 |pmid=41876967 |url=https://pubs.acs.org/doi/10.1021/acs.est.5c17112}}</ref> Higher levels of lead in top soil and dust are associated with higher blood levels of lead in people.<ref name="Li2021">{{cite journal |vauthors=Li Y, Chen J, Bu S, Wang S, Geng X, Guan G, Zhao Q, Ao L, Qu W, Zheng Y, Jin Y, Tang J |title=Blood lead levels and their associated risk factors in Chinese adults from 1980 to 2018 |journal=Ecotoxicol Environ Saf |volume=218 |issue= |article-number=112294 |date=May 2021 |pmid=33984660 |doi=10.1016/j.ecoenv.2021.112294 |bibcode=2021EcoES.21812294L |url=}}</ref><ref name="Han2018">{{cite journal |vauthors=Han Z, Guo X, Zhang B, Liao J, Nie L |title=Blood lead levels of children in urban and suburban areas in China (1997-2015): Temporal and spatial variations and influencing factors |journal=Sci Total Environ |volume=625 |issue= |pages=1659–1666 |date=June 2018 |pmid=29996461 |doi=10.1016/j.scitotenv.2017.12.315 |bibcode=2018ScTEn.625.1659H }}</ref><ref>{{cite journal |last1=Talayero |first1=MJ |last2=Robbins |first2=CR |last3=Smith |first3=ER |last4=Santos-Burgoa |first4=C |title=The association between lead exposure and crime: A systematic review. |journal=PLOS Global Public Health |date=2023 |volume=3 |issue=8 |article-number=e0002177 |doi=10.1371/journal.pgph.0002177 |doi-access=free |pmid=37527230 |pmc=10393136 }}</ref>

=== Sea salt === thumb|right|Horizon and layers of the atmosphere as seen from NASA Earth Observatory: troposphere (darkest), tropopause (brown), stratosphere (gray), mesosphere, thermosphere, and exosphere (blues). Colors are due to the dominant gases and particles in each layer. Sea salt particles are another leading contributor to global particulate matter. Sea salt aerosols (SSAs) can develop over both open water and pack ice.<ref name="Murphy" /> Approximately 80% of the surface of the Southern Hemisphere is oceanic,<ref name=":9">{{Cite journal |last1=Fossum |first1=Kirsten N. |last2=Ovadnevaite |first2=Jurgita |last3=Liu |first3=Dantong |last4=Flynn |first4=Michael |last5=O'Dowd |first5=Colin |last6=Ceburnis |first6=Darius |date=2022-06-15 |title=Background levels of black carbon over remote marine locations |url=https://www.sciencedirect.com/science/article/pii/S0169809522001053 |journal=Atmospheric Research |volume=271 |article-number=106119 |doi=10.1016/j.atmosres.2022.106119 |bibcode=2022AtmRe.27106119F |issn=0169-8095}}</ref> and the average concentration of SSAs is generally higher there than in the Northern Hemisphere.<ref name=":8">{{Cite journal |last1=Jiang |first1=Bei |last2=Xie |first2=Zhouqing |last3=Lam |first3=Paul K. S. |last4=He |first4=Pengzhen |last5=Yue |first5=Fange |last6=Wang |first6=Longquan |last7=Huang |first7=Yikang |last8=Kang |first8=Hui |last9=Yu |first9=Xiawei |last10=Wu |first10=Xudong |date=2021-03-27 |title=Spatial and Temporal Distribution of Sea Salt Aerosol Mass Concentrations in the Marine Boundary Layer From the Arctic to the Antarctic |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JD033892 |journal=Journal of Geophysical Research: Atmospheres |language=en |volume=126 |issue=6 |article-number=e2020JD033892 |doi=10.1029/2020JD033892 |bibcode=2021JGRD..12633892J |issn=2169-897X}}</ref> The production of sea salt aerosols is affected by aspects of the air-sea interface including wind speed, seawater temperature, surface tension, density, and viscosity.<ref name=":8" /> Their distribution also varies with altitude, falling off rapidly at higher levels. Few sea-salt particles rise above the tropopause to reach the upper troposphere.<ref name="Murphy">{{cite journal |last1=Murphy |first1=Daniel M. |last2=Froyd |first2=Karl D. |last3=Bian |first3=Huisheng |last4=Brock |first4=Charles A. |last5=Dibb |first5=Jack E. |last6=DiGangi |first6=Joshua P. |last7=Diskin |first7=Glenn |last8=Dollner |first8=Maximillian |last9=Kupc |first9=Agnieszka |last10=Scheuer |first10=Eric M. |last11=Schill |first11=Gregory P. |last12=Weinzierl |first12=Bernadett |last13=Williamson |first13=Christina J. |last14=Yu |first14=Pengfei |title=The distribution of sea-salt aerosol in the global troposphere |journal=Atmospheric Chemistry and Physics |date=2 April 2019 |volume=19 |issue=6 |pages=4093–4104 |doi=10.5194/acp-19-4093-2019 |doi-access=free|bibcode=2019ACP....19.4093M |language=English |issn=1680-7316}}</ref>

Sea salt aerosols reflect the composition of sea spray and evaporated sea water, consisting mainly of inorganic salts like sodium chloride (NaCl), along with magnesium, sulfate, calcium, bromine and potassium.<ref name="Zhang">{{cite journal |last1=Zhang |first1=Yan |last2=Yang |first2=Lingxiao |last3=Bie |first3=Shujun |last4=Zhao |first4=Tong |last5=Huang |first5=Qi |last6=Li |first6=Jingshu |last7=Wang |first7=Pengcheng |last8=Wang |first8=Yiming |last9=Wang |first9=Wenxing |title=Chemical compositions and the impact of sea salt in atmospheric PM1 and PM2.5 in the coastal area |journal=Atmospheric Research |date=1 March 2021 |volume=250 |article-number=105323 |doi=10.1016/j.atmosres.2020.105323 |url=https://www.sciencedirect.com/science/article/abs/pii/S0169809520312606#:~:text=Newly%20formed%20sea%20salt%20aerosols,SO4%20and%20NaNO3. |issn=0169-8095}}</ref> Sea salt aerosols can include biological and organic matter such as bacteria, viruses, proteins, enzymes, dissolved organic carbon, fatty acids and sugars.<ref name="Schiffer" /> SSA particles are key to the formation of clouds: hygroscopicity, the ability of an individual particle to take up water and eventually become a cloud droplet, is a function of particle size and composition. Sea salt aerosols affect climate both directly by scattering incoming solar radiation and indirectly through cloud formation.<ref name="Schiffer">{{cite journal | title=Sea Spray Aerosol: Where Marine Biology Meets Atmospheric Chemistry| year=2018| pmc=6311946| last1=Schiffer| first1=J. M.| last2=Mael| first2=L. E.| last3=Prather| first3=K. A.| last4=Amaro| first4=R. E.| last5=Grassian| first5=V. H.| journal=ACS Central Science| volume=4| issue=12| pages=1617–1623| doi=10.1021/acscentsci.8b00674| doi-access=free| pmid=30648145| bibcode=2018ACSCS...4.1617S}}</ref> They are relatively large compared to other aerosols.<ref name="Murphy" />

=== Organic matter === Organic matter (OM) contains carbon-based compounds, which can be either primary or secondary. Carbon combines with hydrogen and other elements to form complex molecules like carbohydrates, proteins, and DNA in living organisms.<ref>{{cite book |last1=Seager |first1=Spencer L. |last2=Slabaugh |first2=Michael R. |last3=Hansen |first3=Maren S. |title=Chemistry for today: general, organic, and biochemistry |date=2022 |publisher=Cengage |location=Boston, MA |isbn=978-0-357-45338-4 |edition=Tenth}}</ref> Burning of living or once-living matter, whether natural or human-caused, releases black carbon (BC) and organic carbon (OC),<ref>{{cite journal |last1=Karthik |first1=V |last2=Vijay Bhaskar |first2=B |last3=Ramachandran |first3=S |last4=Gertler |first4=AW |title=Quantification of organic carbon and black carbon emissions, distribution, and carbon variation in diverse vegetative ecosystems across India. |journal=Environmental Pollution |date=15 September 2022 |volume=309 |article-number=119790 |doi=10.1016/j.envpol.2022.119790 |pmid=35850316 |bibcode=2022EPoll.30919790K }}</ref> both of which are part of smoke and soot.<ref>{{cite journal |last1=Kahnert |first1=Michael |last2=Kanngießer |first2=Franz |title=Modelling optical properties of atmospheric black carbon aerosols |journal=Journal of Quantitative Spectroscopy and Radiative Transfer |date=1 March 2020 |volume=244 |article-number=106849 |doi=10.1016/j.jqsrt.2020.106849 |bibcode=2020JQSRT.24406849K |issn=0022-4073}}</ref> Approximately 85% of the world's population lives in the Northern Hemisphere, where human activities are the dominant sources of organic matter and fine particulate matter (PM25).<ref name=":9" />

Black carbon tends to be released at higher temperatures<ref name="Zhang2023">{{cite journal |last1=Zhang |first1=Z |last2=Cheng |first2=Y |last3=Liang |first3=L |last4=Liu |first4=J |title=The Measurement of Atmospheric Black Carbon: A Review. |journal=Toxics |date=1 December 2023 |volume=11 |issue=12 |doi=10.3390/toxics11120975 |doi-access=free|pmid=38133376 |pmc=10748019 }}</ref> and contains mostly pure (elemental) carbon.<ref name="Gupta" /> Organic carbon contains additional materials and is more complex.<ref name="Hu" /><ref name="Gupta" /> Bioaerosols are a form of organic carbon, biological fragments of living microbial, fungal, animal, and plant sources.<ref name="Mack" /> Microplastics are synthetic polymer chains that are carbon-based.<ref name="Uchmanowicz">{{cite journal |last1=Uchmanowicz |first1=D |last2=Styszko |first2=K |last3=Chen |first3=X |last4=Terribile |first4=G |last5=Jakhar |first5=R |last6=Sancini |first6=G |last7=Pyssa |first7=J |title=Microplastics in Airborne Particulate Matter: A Comprehensive Review of Separation Techniques, In Vitro Toxicity and Health Impacts. |journal=International Journal of Molecular Sciences |date=23 October 2025 |volume=26 |issue=21 |article-number=10332 |doi=10.3390/ijms262110332 |doi-access=free |pmid=41226370 |pmc=12607753 }}</ref><ref name="Saha">{{cite journal |last1=Saha |first1=SC |last2=Saha |first2=G |title=Effect of microplastics deposition on human lung airways: A review with computational benefits and challenges. |journal=Heliyon |date=30 January 2024 |volume=10 |issue=2 |article-number=e24355 |doi=10.1016/j.heliyon.2024.e24355 |doi-access=free |pmid=38293398 |pmc=10826726 |bibcode=2024Heliy..1024355S }}</ref> Organic matter can influence the atmospheric radiation field by both scattering and absorption. Black carbon is the most strongly light-absorbing aerosol component, while organic carbon tends to be less absorptive, depending on its structure.<ref name="Gupta">{{cite journal |last1=Gupta |first1=T |last2=Rajeev |first2=P |last3=Rajput |first3=R |title=Emerging Major Role of Organic Aerosols in Explaining the Occurrence, Frequency, and Magnitude of Haze and Fog Episodes during Wintertime in the Indo Gangetic Plain. |journal=ACS Omega |date=18 January 2022 |volume=7 |issue=2 |pages=1575–1584 |doi=10.1021/acsomega.1c05467 |doi-access=free |pmid=35071853 |pmc=8771687 |bibcode=2022ACSOm...7.1575G }}</ref> In addition to carbon compounds, the burning of petroleum and oil also releases sulfur oxides and many other chemicals into the atmosphere.<ref name="Damiati">{{cite journal |last1=Damiati |first1=S |last2=AlMashrea |first2=BA |last3=Rabiei |first3=N |last4=Sujatha |first4=AP |last5=Sabir |first5=DK |last6=Alhosani |first6=M |last7=Kodzius |first7=R |title=Aerosol Pollutants and Health: Role of Size and Chemical Composition. |journal=Public Health Challenges |date=December 2025 |volume=4 |issue=4 |article-number=e70134 |doi=10.1002/puh2.70134 |pmid=41020050 |pmc=12466196 }}</ref><ref name="Hu">{{cite journal |last1=Hu |first1=Dawei |last2=Alfarra |first2=M. Rami |last3=Szpek |first3=Kate |last4=Langridge |first4=Justin M. |last5=Cotterell |first5=Michael I. |last6=Belcher |first6=Claire |last7=Rule |first7=Ian |last8=Liu |first8=Zixia |last9=Yu |first9=Chenjie |last10=Shao |first10=Yunqi |last11=Voliotis |first11=Aristeidis |last12=Du |first12=Mao |last13=Smith |first13=Brett |last14=Smallwood |first14=Greg |last15=Lobo |first15=Prem |last16=Liu |first16=Dantong |last17=Haywood |first17=Jim M. |last18=Coe |first18=Hugh |last19=Allan |first19=James D. |title=Physical and chemical properties of black carbon and organic matter from different combustion and photochemical sources using aerodynamic aerosol classification |journal=Atmospheric Chemistry and Physics |date=3 November 2021 |volume=21 |issue=21 |pages=16161–16182 |doi=10.5194/acp-21-16161-2021 |doi-access=free|url=https://acp.copernicus.org/articles/21/16161/2021/ |language=English |issn=1680-7316}}</ref>

=== Secondary organic aerosols === Secondary organic aerosols (SOA) are major components of PM2.5, small inhalable particulate matter that is linked to health problems. Secondary organic aerosols form when gaseous vapors in the atmosphere (e.g. SO2, NO and NO2, NH3, VOCs) react chemically to produce compounds that then form particles. Precursor gases may be anthropogenic (e.g. from biomass and fossil fuel combustion) or natural (e.g. from dust, forest fires, or sea salt aerosols) in origin. Aerosols can mix rapidly in ambient air, forming new chemical compounds as well as diluting their concentration with distance from an emissions source.<ref name="Manavi">{{cite journal |last1=Manavi |first1=Stella E.I. |last2=Aktypis |first2=Andreas |last3=Siouti |first3=Evangelia |last4=Skyllakou |first4=Ksakousti |last5=Myriokefalitakis |first5=Stelios |last6=Kanakidou |first6=Maria |last7=Pandis |first7=Spyros N. |title=Atmospheric aerosol spatial variability: Impacts on air quality and climate change |journal=One Earth |date=March 2025 |volume=8 |issue=3 |article-number=101237 |doi=10.1016/j.oneear.2025.101237 |issn=2590-3322}}</ref><ref name="Delbari">{{cite journal |last1=Delbari |first1=Seyed Hamid |last2=Zare Shahne |first2=Maryam |last3=Hosseini |first3=Vahid |title=An Analysis of Primary Contributing Sources to the PM2.5 Composition in a Port City in Canada Influenced by Traffic, Marine, and Wildfire Emissions |journal=Atmospheric Environment |date=1 October 2024 |volume=334 |article-number=120712 |doi=10.1016/j.atmosenv.2024.120712 |url=https://www.sciencedirect.com/science/article/pii/S135223102400387X |issn=1352-2310}}</ref>

The smallest class of particulates, PM1 frequently contains sulfate, ammonium, and nitrate.<ref name="Li40516540">{{cite journal |last1=Li |first1=C |last2=Martin |first2=RV |last3=van Donkelaar |first3=A |last4=Jimenez |first4=JL |last5=Zhang |first5=Q |last6=Turner |first6=JR |last7=Liu |first7=X |last8=Rowe |first8=M |last9=Meng |first9=J |last10=Yu |first10=W |last11=Thurston |first11=GD |title=Estimates of submicron particulate matter (PM(1)) concentrations for 1998-2022 across the contiguous USA: leveraging measurements of PM(1) with nationwide PM(2·5) component data. |journal=The Lancet. Planetary Health |date=June 2025 |volume=9 |issue=6 |pages=e491–e502 |doi=10.1016/S2542-5196(25)00094-4 |pmid=40516540 |pmc=12466669 }}</ref> Primary gases such as sulfur and nitrogen oxides can oxidize to form secondary particles of sulfuric acid (liquid) and nitric acid (gaseous). In the presence of ammonia, they often form ammonium salts such as ammonium sulfate and ammonium nitrate (both can be dry or in aqueous solution).<ref name="Manavi" /> Secondary sulfate and nitrate aerosols tend to reflect solar radiation, but their ability to scatter light is affected by water absorption.<ref>{{cite journal |last1=Zhang |first1=Xi |last2=Murakami |first2=Takuya |last3=Wang |first3=Jinhe |last4=Aikawa |first4=Masahide |title=Sources, species and secondary formation of atmospheric aerosols and gaseous precursors in the suburb of Kitakyushu, Japan |journal=Science of the Total Environment |date=1 April 2021 |volume=763 |article-number=143001 |doi=10.1016/j.scitotenv.2020.143001 |pmid=33131869 |bibcode=2021ScTEn.76343001Z |issn=0048-9697}}</ref><ref>{{cite journal |last1=Li |first1=Jing |last2=Carlson |first2=Barbara E. |last3=Yung |first3=Yuk L. |last4=Lv |first4=Daren |last5=Hansen |first5=James |last6=Penner |first6=Joyce E. |last7=Liao |first7=Hong |last8=Ramaswamy |first8=V. |last9=Kahn |first9=Ralph A. |last10=Zhang |first10=Peng |last11=Dubovik |first11=Oleg |last12=Ding |first12=Aijun |last13=Lacis |first13=Andrew A. |last14=Zhang |first14=Lu |last15=Dong |first15=Yueming |title=Scattering and absorbing aerosols in the climate system |journal=Nature Reviews Earth & Environment |date=June 2022 |volume=3 |issue=6 |pages=363–379 |doi=10.1038/s43017-022-00296-7 |bibcode=2022NRvEE...3..363L |language=en |issn=2662-138X}}</ref><ref>{{cite journal |last1=Li |first1=Lingjun |last2=Li |first2=Mengren |last3=Fan |first3=Xiaolong |last4=Chen |first4=Yuping |last5=Lin |first5=Ziyi |last6=Hou |first6=Anqi |last7=Zhang |first7=Siqing |last8=Zheng |first8=Ronghua |last9=Chen |first9=Jinsheng |title=Measurement report: The variation properties of aerosol hygroscopic growth related to chemical composition during new particle formation days in a coastal city of Southeast China |journal=Atmospheric Chemistry and Physics |date=27 March 2025 |volume=25 |issue=6 |pages=3669–3685 |doi=10.5194/acp-25-3669-2025 |doi-access=free|bibcode=2025ACP....25.3669L |language=English |issn=1680-7316}}</ref><ref name="Manavi" />

=== Composition of wildfires and haze === Due to effects of climate change, wildfire seasons have become increasingly severe globally, producing large amounts of particulate matter that can spread over thousands of miles. Wildfire smoke contains high levels of PM{{sub|2.5}}, carbon monoxide, carbon dioxide, heavy metals like lead, and PAHs, which combine to form secondary pollutants. Wildfire smoke particulate matter is more toxic than similar weights of PM from non-fire-related ambient air.<ref name="Basilio">{{cite journal |last1=Basilio |first1=E |last2=Chen |first2=R |last3=Fernandez |first3=AC |last4=Padula |first4=AM |last5=Robinson |first5=JF |last6=Gaw |first6=SL |title=Wildfire Smoke Exposure during Pregnancy: A Review of Potential Mechanisms of Placental Toxicity, Impact on Obstetric Outcomes, and Strategies to Reduce Exposure. |journal=International Journal of Environmental Research and Public Health |date=22 October 2022 |volume=19 |issue=21 |article-number=13727 |doi=10.3390/ijerph192113727 |doi-access=free |pmid=36360613 |pmc=9657128 |bibcode=2022IJERP..1913727B }}</ref>

Haze, particulate matter that generally causes visual effects, tends to consist of sulfur dioxide, nitrogen oxides, carbon monoxide, mineral dust, and organic matter in dry air. The particles are hygroscopic due to the presence of sulfur, and SO{{sub|2}} is converted to sulfate when high humidity and low temperatures are present.<ref>{{cite journal |last1=Su |first1=Hang |last2=Cheng |first2=Yafang |last3=Pöschl |first3=Ulrich |title=New Multiphase Chemical Processes Influencing Atmospheric Aerosols, Air Quality, and Climate in the Anthropocene |journal=Accounts of Chemical Research |date=20 October 2020 |volume=53 |issue=10 |pages=2034–2043 |doi=10.1021/acs.accounts.0c00246 |pmid=32927946 |pmc=7581287 |issn=0001-4842}}</ref><ref>{{cite journal |last1=Liu |first1=SK |last2=Cai |first2=S |last3=Chen |first3=Y |last4=Xiao |first4=B |last5=Chen |first5=P |last6=Xiang |first6=XD |title=The effect of pollutional haze on pulmonary function. |journal=Journal of Thoracic Disease |date=January 2016 |volume=8 |issue=1 |pages=E41-56 |doi=10.3978/j.issn.2072-1439.2016.01.18 |pmid=26904252 |pmc=4740132 }}</ref> This causes reduced visibility and red-orange-yellow colors.<ref>{{cite web |title=Haze & Visibility |url=https://www.mass.gov/info-details/haze-visibility |website=Mass.gov |access-date=26 March 2026 |language=en}}</ref>

== Measurement == {{Main|Air pollution measurement}}

{{See also|Particulate matter sampler}} Particulates have been measured in increasingly sophisticated ways since air pollution was first systematically studied in the early 20th century.<ref name="Hinds">{{cite book |last1=Hinds |first1=William C. |last2=Zhu |first2=Yifang |title=Aerosol technology: properties, behavior, and measurement of airborne particles |date=2022 |publisher=Wiley |location=Hoboken, NJ |isbn=978-1-119-49404-1 |edition=Third}}</ref><ref name="Nicklin">{{cite journal |last1=Nicklin |first1=Daniel |last2=Gohari Darabkhani |first2=Hamidreza |title=Techniques to measure particulate matter emissions from stationary sources: A critical technology review using Multi Criteria Decision Analysis (MCDA) |journal=Journal of Environmental Management |date=15 October 2021 |volume=296 |article-number=113167 |doi=10.1016/j.jenvman.2021.113167 |pmid=34237670 |bibcode=2021JEnvM.29613167N |url=https://www.sciencedirect.com/science/article/abs/pii/S0301479721012299 |issn=0301-4797}}</ref> The earliest methods included relatively crude Ringelmann charts, which were grey-shaded cards against which emissions from smokestacks could be visually compared, and deposit gauges, which collected the soot deposited in a particular location so it could be weighed.<ref name="brimblecombe">{{cite book|author1-link=Peter Brimblecombe |last1=Brimblecombe |first1=Peter |title=The Big Smoke: A History of Air Pollution in London Since Medieval Times |date=1987 |publisher=Routledge |isbn=978-1-136-70329-4 |pages=136–160}}</ref>

[[File:Luftguete messstation.jpg|thumb|upright|Air pollution measurement station in Emden, Germany]] Modern air pollution measurement techniques characterize ambient air quality using data from three main sources: direct measurements of on site sources, computer models, and remote sensing platforms such as satellites.<ref name="Holloway">{{cite journal |last1=Holloway |first1=T |last2=Miller |first2=D |last3=Anenberg |first3=S |last4=Diao |first4=M |last5=Duncan |first5=B |last6=Fiore |first6=AM |last7=Henze |first7=DK |last8=Hess |first8=J |last9=Kinney |first9=PL |last10=Liu |first10=Y |last11=Neu |first11=JL |last12=O'Neill |first12=SM |last13=Odman |first13=MT |last14=Pierce |first14=RB |last15=Russell |first15=AG |last16=Tong |first16=D |last17=West |first17=JJ |last18=Zondlo |first18=MA |title=Satellite Monitoring for Air Quality and Health. |journal=Annual Review of Biomedical Data Science |date=20 July 2021 |volume=4 |pages=417–447 |doi=10.1146/annurev-biodatasci-110920-093120 |pmid=34465183}}</ref> Direct methods of measuring particulates can determine the total mass of particles per unit volume of air (particle mass concentration) using techniques such as gravimetric air quality analysis, beta attenuation monitoring, tapered element oscillating microbalances, and aethalometers (for black carbon).<ref name="aqeg-particulates">{{cite web |title=Particulate Matter in the United Kingdom Summary |url=https://uk-air.defra.gov.uk/assets/documents/reports/aqeg/pm-summary.pdf |website=Air Quality Expert Group |publisher=Defra |access-date=28 June 2023 |date=2005 |archive-date=19 January 2022 |archive-url=https://web.archive.org/web/20220119185510/http://uk-air.defra.gov.uk/assets/documents/reports/aqeg/pm-summary.pdf |url-status=live }}</ref><ref>{{cite web |title=LIST OF DESIGNATED REFERENCE AND EQUIVALENT METHODS |url=https://www.epa.gov/system/files/documents/2025-12/amtic-list-december-2025_508-compliant.pdf |website=UNITED STATES ENVIRONMENTAL PROTECTION AGENCY |access-date=22 April 2026}}</ref> Sometimes it is more useful to measure the total number of particles per unit volume of air (particle number concentration). This can be done with optical particle counters and condensation particle counters.<ref name=cpc-manch>{{cite web |title=Condensation particle counters |url=http://www.cas.manchester.ac.uk/restools/instruments/aerosol/cpc/ |website=Center for Atmospheric Science |publisher=University of Manchester |access-date=5 July 2023 |archive-date=30 June 2023 |archive-url=https://web.archive.org/web/20230630093414/http://www.cas.manchester.ac.uk/restools/instruments/aerosol/cpc/ |url-status=live }}</ref><ref>{{Cite web|url=https://uk-air.defra.gov.uk/networks/network-info?view=particle|title=Particle Numbers and Concentrations Network- Defra, UK|first=Food and Rural Affairs (Defra) webmaster@defra gsi gov uk|last=Department for Environment|website=uk-air.defra.gov.uk|access-date=5 July 2023|archive-date=5 July 2023|archive-url=https://web.archive.org/web/20230705125741/https://uk-air.defra.gov.uk/networks/network-info?view=particle|url-status=live}}</ref> To measure the atomic composition of particulate samples, techniques such as X-ray spectrometry can be used.<ref>{{cite journal |last1=Marguí |first1=E |last2=Queralt |first2=I |last3=de Almeida |first3=E |title=X-ray fluorescence spectrometry for environmental analysis: Basic principles, instrumentation, applications and recent trends. |journal=Chemosphere |date=September 2022 |volume=303 |issue=Pt 1 |article-number=135006 |doi=10.1016/j.chemosphere.2022.135006 |pmid=35605725 |bibcode=2022Chmsp.30335006M }}</ref><ref>{{cite journal |last1=Tang |first1=F |last2=Qi |first2=S |last3=Tang |first3=X |last4=Wen |first4=X |last5=Zhang |first5=Y |last6=Peng |first6=G |last7=Huang |first7=J |last8=Shang |first8=G |last9=Zhang |first9=X |last10=Chen |first10=F |last11=Xu |first11=Y |last12=Cai |first12=J |title=Analysis of PM(2.5) Morphology, Composition and Health Risk in a Multi-Chair Dental Clinic. |journal=Environmental Toxicology |date=October 2025 |volume=40 |issue=10 |pages=1207–1219 |doi=10.1002/tox.24519 |pmid=40202132 |pmc=12432807 }}</ref><ref>{{cite journal |last1=Kayser |first1=Y |last2=Osán |first2=J |last3=Hönicke |first3=P |last4=Beckhoff |first4=B |title=Reliable compositional analysis of airborne particulate matter beyond the quantification limits of total reflection X-ray fluorescence. |journal=Analytica Chimica Acta |date=1 February 2022 |volume=1192 |article-number=339367 |doi=10.1016/j.aca.2021.339367 |pmid=35057956 |bibcode=2022AcAC.119239367K }}</ref> Special filters and detection techniques can be used to select samples of a particular size (e.g. PM{{sub|10}} or PM{{sub|2.5}}) or chemical composition (e.g. black carbon)<ref name="Tronville">{{cite journal |last1=Tronville |first1=P |last2=Gentile |first2=V |last3=Marval |first3=J |title=Guidelines for measuring and reporting particle removal efficiency in fibrous media. |journal=Nature Communications |date=1 September 2023 |volume=14 |issue=1 |page=5323 |doi=10.1038/s41467-023-41154-4 |pmid=37658063 |pmc=10474009 |bibcode=2023NatCo..14.5323T }}</ref><ref name="Jeronimo">{{cite journal |last1=Jeronimo |first1=M |last2=Stewart |first2=Q |last3=Weakley |first3=AT |last4=Giacomo |first4=J |last5=Zhang |first5=X |last6=Hyslop |first6=N |last7=Dillner |first7=AM |last8=Shupler |first8=M |last9=Brauer |first9=M |title=Analysis of black carbon on filters by image-based reflectance. |journal=Atmospheric Environment (Oxford, England : 1994) |date=15 February 2020 |volume=223 |article-number=117300 |doi=10.1016/j.atmosenv.2020.117300 |pmid=32095102 |pmc=7039653 |bibcode=2020AtmEn.22317300J }}</ref> and to track their distribution over time.<ref>{{cite journal |last1=Power |first1=AL |last2=Tennant |first2=RK |last3=Stewart |first3=AG |last4=Gosden |first4=C |last5=Worsley |first5=AT |last6=Jones |first6=R |last7=Love |first7=J |title=The evolution of atmospheric particulate matter in an urban landscape since the Industrial Revolution. |journal=Scientific Reports |date=2 June 2023 |volume=13 |issue=1 |page=8964 |doi=10.1038/s41598-023-35679-3 |pmid=37268751 |pmc=10238512 |bibcode=2023NatSR..13.8964P }}</ref> Human-generated particulates are often smaller in size (e.g. PM2.5 or PM1) than naturally formed ones.<ref name="Shaffer" /><ref name="Li40516540" />

thumb|False-color map based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite. The percentage of small particles is displayed by color, from green (few small particles) to red (many small particles). Gray: the sensor did not collect data.<ref name=modis>{{cite web | url=https://earthobservatory.nasa.gov/global-maps/MODAL2_M_AER_RA | title=Aerosol Size, Earth Observatory | date=31 August 2016 | publisher=NASA | access-date=24 March 2023 | archive-date=24 March 2023 | archive-url=https://web.archive.org/web/20230324113842/https://earthobservatory.nasa.gov/global-maps/MODAL2_M_AER_RA | url-status=live }}{{PD-notice}}</ref> Satellite-based estimates of PM2.5 are important tools. Satellite measurements of aerosols are based on the fact that particles change the way the atmosphere reflects and absorbs visible and infrared light. Satellites measure aerosol optical depth (AOD) and other factors that indicate the concentration and distribution of particulates in the atmosphere. PM2.5 concentrations are then inferred from the satellite data by using models or ground-based monitoring data. Combining these approaches can enhance the spatial coverage of PM2.5, to show patterns of distribution and movement in space and time. Such information can be used to create smoke forecasts and pollution advisories.<ref name="Holloway"/><ref>{{cite journal |vauthors=Di Antonio L, Di Biagio C, Foret G, Formenti P, Siour G, Doussin JF, Beekmann M |date=6 October 2023 |title=Aerosol optical depth climatology from the high-resolution MAIAC product over Europe: differences between major European cities and their surrounding environments |journal=Atmos. Chem. Phys. |volume=23 |issue=19 |pages=12455–12475 |doi=10.5194/acp-23-12455-2023 |bibcode=2023ACP....2312455D |doi-access=free}}</ref><ref>{{cite journal |title=Aerosol optical depth regime over megacities of the world |date=15 December 2022 |doi=10.5194/acp-22-15703-2022 |doi-access=free |journal=Atmos. Chem. Phys. |volume=22 |issue=24 |pages=15703–15727 |bibcode=2022ACP....2215703P |vauthors=Papachristopoulou K, Raptis IP, Gkikas A, Fountoulakis I, Masoom A, Kazadzis S}}</ref>

==Movement and deposition== {{Main|Deposition (aerosol physics)}}

Satellite data has shown that volcanic eruptions can send ash and particles high into the atmosphere, with fine particulates remaining in the air for long periods, traveling over long distances, and affecting global climate.<ref>{{cite journal |last1=Zhu |first1=Yunqian |last2=Toon |first2=Owen B. |last3=Jensen |first3=Eric J. |last4=Bardeen |first4=Charles G. |last5=Mills |first5=Michael J. |last6=Tolbert |first6=Margaret A. |last7=Yu |first7=Pengfei |last8=Woods |first8=Sarah |title=Persisting volcanic ash particles impact stratospheric SO2 lifetime and aerosol optical properties |journal=Nature Communications |date=10 September 2020 |volume=11 |issue=1 |page=4526 |doi=10.1038/s41467-020-18352-5 |pmid=32913208 |pmc=7483524 |language=en |issn=2041-1723}}</ref><ref>{{cite web |title=How Volcanoes Influence Climate {{!}} Center for Science Education |url=https://scied.ucar.edu/learning-zone/how-climate-works/how-volcanoes-influence-climate |website=University Corporation for Atmospheric Research |access-date=2 April 2026}}</ref><ref>{{cite web |title=Satellite Catalogs Volcanic Sulfur Emissions - NASA Science |url=https://science.nasa.gov/earth/earth-observatory/satellite-catalogs-volcanic-sulfur-emissions-89813/ |website=NASA Science |access-date=2 April 2026 |date=10 March 2017}}</ref> Particulate matter from wildfires in the western United States and Canada can travel to the United Kingdom and northern France in a few days.<ref>{{cite web | url=https://earthobservatory.nasa.gov/images/90980/an-american-aerosol-in-paris | title=An American Aerosol in Paris| date=15 September 2017}}</ref> Dust thrown into the air by sandstorms in the Sahara travels from North Africa to North America.<ref>{{cite journal |last1=Georgakopoulou |first1=VE |last2=Taskou |first2=C |last3=Diamanti |first3=A |last4=Beka |first4=D |last5=Papalexis |first5=P |last6=Trakas |first6=N |last7=Spandidos |first7=DA |title=Saharan dust and respiratory health: Understanding the link between airborne particulate matter and chronic lung diseases (Review). |journal=Experimental and Therapeutic Medicine |date=December 2024 |volume=28 |issue=6 |page=460 |doi=10.3892/etm.2024.12750 |pmid=39478735 |pmc=11523266 }}</ref>

thumb|right|300px|Global atmospheric circulation: Earth's rotation creates characteristic wind belts Particles are transported globally and locally via characteristic atmospheric and oceanic currents, transitioning between air and water at the air-sea interface.<ref name="DeVries">{{cite journal |last1=DeVries |first1=Tim |title=The Ocean Carbon Cycle |journal=Annual Review of Environment and Resources |date=17 October 2022 |volume=47 |issue= |pages=317–341 |doi=10.1146/annurev-environ-120920-111307 |url=https://www.annualreviews.org/content/journals/10.1146/annurev-environ-120920-111307 |language=en |issn=1543-5938}}</ref><ref name="Gray">{{cite journal |last1=Gray |first1=Alison R. |title=The Four-Dimensional Carbon Cycle of the Southern Ocean |journal=Annual Review of Marine Science |date=17 January 2024 |volume=16 |issue= |pages=163–190 |doi=10.1146/annurev-marine-041923-104057 |pmid=37738480 |language=en |issn=1941-1405}}</ref><ref name="Norgren">{{cite journal |last1=Norgren |first1=M. |last2=Kalnajs |first2=L. E. |last3=Deshler |first3=T. |title=Measurements of Total Aerosol Concentration in the Stratosphere: A New Balloon-Borne Instrument and a Report on the Existing Measurement Record |journal=Journal of Geophysical Research: Atmospheres |date=28 July 2024 |volume=129 |issue=14 |article-number=e2024JD040992 |doi=10.1029/2024JD040992 |bibcode=2024JGRD..12940992N |language=en |issn=2169-897X}}</ref> Particles move between land, water and air through mechanisms such as emission, suspension, and deposition. Circulation models take into account the release of particulates into the air, conditions under which they remain in air, their physical transport, and their removal from the atmosphere.<ref name="Baker">{{cite journal |last1=Baker |first1=AR |last2=Landing |first2=WM |last3=Bucciarelli |first3=E |last4=Cheize |first4=M |last5=Fietz |first5=S |last6=Hayes |first6=CT |last7=Kadko |first7=D |last8=Morton |first8=PL |last9=Rogan |first9=N |last10=Sarthou |first10=G |last11=Shelley |first11=RU |last12=Shi |first12=Z |last13=Shiller |first13=A |last14=van Hulten |first14=MMP |title=Trace element and isotope deposition across the air-sea interface: progress and research needs. |journal=Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences |date=28 November 2016 |volume=374 |issue=2081 |doi=10.1098/rsta.2016.0190 |pmid=29035268 |pmc=5069538 |bibcode=2016RSPTA.37460190B }}</ref>

Wet deposition or precipitation scavenging is the removal of particulate matter from the atmosphere through interactions with clouds, precipitation, and other particles that lead to settling. Particles may act as cloud condensation nuclei to create cloud droplets or collide with already-formed raindrops.<ref name="ASE"/>

Dry deposition involves the transfer of particles from the atmosphere onto surfaces (soil, water, living things, buildings) independent of precipitation. Dry deposition of particles is affected by gravity, wind speed, turbulence and the presence of surfaces (which can include other particles).<ref name="ASE">{{cite web |title=Air-Surface Exchange Process Overview |url=https://www.epa.gov/cmaq/air-surface-exchange-process-overview |website=US EPA |access-date=2 April 2026 |language=en |date=10 November 2016}}</ref><ref>{{cite journal |last1=Farmer |first1=Delphine K. |last2=Boedicker |first2=Erin K. |last3=DeBolt |first3=Holly M. |title=Dry Deposition of Atmospheric Aerosols: Approaches, Observations, and Mechanisms |journal=Annual Review of Physical Chemistry |date=20 April 2021 |volume=72 |issue= 1|pages=375–397 |doi=10.1146/annurev-physchem-090519-034936 |pmid=33472381 |bibcode=2021ARPC...72..375F |language=en |issn=0066-426X}}</ref>

Sedimentation (settling due to gravity) and evaporation are influenced by physical and chemical factors including temperature, humidity, particle radius, particle volume, and height at which an emission is released.<ref name="Nagy"/> In general, the smaller and lighter a particle is, the longer it will stay suspended in air. Larger particles (greater than 50–100 μm in diameter) tend to settle to the ground quickly as a result of gravity, and may travel no more than a few meters from their source.<ref name="Nagy"/> The smallest particles (less than 1 micrometer) can stay in the atmosphere for weeks, and are mostly likely to be removed by precipitation. They may also become resuspended and continue to circulate due to turbulence or collisions with other particulates.<ref name="Nagy">{{cite journal |last1=Nagy |first1=A |last2=Czitrovszky |first2=A |last3=Lehoczki |first3=A |last4=Farkas |first4=Á |last5=Füri |first5=P |last6=Osán |first6=J |last7=Groma |first7=V |last8=Kugler |first8=S |last9=Micsinai |first9=A |last10=Horváth |first10=A |last11=Ungvári |first11=Z |last12=Müller |first12=V |title=Creating respiratory pathogen-free environments in healthcare and nursing-care settings: a comprehensive review. |journal=GeroScience |date=February 2025 |volume=47 |issue=1 |pages=543–571 |doi=10.1007/s11357-024-01379-7 |pmid=39392557 |pmc=11872867 }}</ref>

Solubility and evaporation significantly affect the size, phase, and behavior of particles and aerosols.<ref name="Nagy"/> Aerosol particles grow by absorbing water at high relative humidity. Evaporation of water from particulates can lead to phase changes between solid, liquid, or gas, and the formation of crusts and solid particles. Changes of phase, internal structure, and diameter can affect both physical and chemical behaviors of particulate matter.<ref name="Rezaei">{{cite journal |last1=Rezaei |first1=M |last2=Netz |first2=RR |title=Water evaporation from solute-containing aerosol droplets: Effects of internal concentration and diffusivity profiles and onset of crust formation. |journal=Physics of Fluids (Woodbury, N.Y. : 1994) |date=September 2021 |volume=33 |issue=9 |page=091901 |doi=10.1063/5.0060080 |pmid=34588758 |pmc=8474021 |arxiv=2104.03865 |bibcode=2021PhFl...33i1901R }}</ref>

== Health effects ==  {{anchor|Health effects}}

{{See also|Health effects of wood dust|Health and environmental impact of the coal industry}}

===Size, shape, and solubility matter=== Health effects of particulate matter are influenced by factors such as particle size, shape, solubility, charge, chemical composition, and concentration and rate of exposure.<ref name="Mack">{{cite journal |last1=Mack |first1=SM |last2=Madl |first2=AK |last3=Pinkerton |first3=KE |title=Respiratory Health Effects of Exposure to Ambient Particulate Matter and Bioaerosols. |journal=Comprehensive Physiology |date=18 December 2019 |volume=10 |issue=1 |pages=1–20 |doi=10.1002/cphy.c180040 |pmid=31853953 |pmc=7553137 |isbn=978-0-470-65071-4 }}</ref> Toxicity of particles tends to increase with smaller size, larger surface area, accumulation of material on particle surfaces, and other physical characteristics of particles.<ref name="Schraufnagel2020">{{cite journal |last1=Schraufnagel |first1=DE |title=The health effects of ultrafine particles. |journal=Experimental & Molecular Medicine |date=March 2020 |volume=52 |issue=3 |pages=311–317 |doi=10.1038/s12276-020-0403-3 |pmid=32203102 |pmc=7156741 }}</ref><ref name="Xue" />

====Size==== thumb|right|300px|Penetration of airborne particulate matter into the lungs depends on size<ref name="Hamanaka" /> The size of particulate matter (PM) is a key determinant of its potential to cause health problems.<ref name="Hamanaka" /> Particles that enter the respiratory system may either be exhaled and leave the lungs, or be deposited and remain in the lungs.<ref name="ZhangL2021">{{cite journal |last1=Zhang |first1=L |last2=Ou |first2=C |last3=Magana-Arachchi |first3=D |last4=Vithanage |first4=M |last5=Vanka |first5=KS |last6=Palanisami |first6=T |last7=Masakorala |first7=K |last8=Wijesekara |first8=H |last9=Yan |first9=Y |last10=Bolan |first10=N |last11=Kirkham |first11=MB |title=Indoor Particulate Matter in Urban Households: Sources, Pathways, Characteristics, Health Effects, and Exposure Mitigation. |journal=International Journal of Environmental Research and Public Health |date=21 October 2021 |volume=18 |issue=21 |article-number=11055 |doi=10.3390/ijerph182111055 |doi-access=free |pmid=34769574 |pmc=8582694 |bibcode=2021IJERP..1811055Z }}</ref> Particles of different sizes deposit in different regions of the respiratory tract, leading to various health effects.<ref name="Hamanaka" /> Particles that can only reach as far as the upper respiratory tract are called ''inhalable'', while particles that can enter the lungs are called ''respirable''.<ref name="Mack" /> Particles are grouped by size.<ref name="EPA2019">{{cite web |title=Health and Environmental Effects of Particulate Matter (PM) |publisher=United States Environmental Protection Agency |date=11 April 2019 |url=https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm |access-date=24 October 2023 |archive-date=15 December 2019 |archive-url=https://web.archive.org/web/20191215135625/https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm |url-status=live }}</ref><ref name="Xue">{{cite journal |last1=Xue |first1=Tao |last2=Kang |first2=Ning |last3=Zhu |first3=Tong |title=Health-Oriented Strategy for Clean Air and Climate Actions: Differential Health Effects of Atmospheric Components |journal=Annual Review of Public Health |date=4 April 2025 |volume=46 |issue= 1|pages=275–294 |doi=10.1146/annurev-publhealth-071723-015722 |pmid=39705181 |language=en |issn=0163-7525}}</ref> * '''Coarse particles''' (PM{{sub|10}}), with diameters between 2.5 and 10 micrometers, can be inhaled and can deposit in the upper airways, including the nose, throat, and bronchi.<ref name="EPA2019" /> Exposure to PM{{sub|10}} is associated with respiratory diseases (e.g. asthma, bronchitis, and rhinosinusitis),<ref name="Hamanaka" /><ref name="Kim">{{cite journal |last1=Kim |first1=JS |last2=Lee |first2=DC |title=Association Between Particulate Matter Exposure and Chronic Rhinosinusitis. |journal=Journal of Rhinology |date=July 2023 |volume=30 |issue=2 |pages=57–61 |doi=10.18787/jr.2023.00017 |pmid=39664877 |pmc=11524351 }}</ref> and cardiovascular effects (e.g. heart attacks and arrhythmias due to systemic inflammation and oxidative stress).<ref name="Krittanawong">{{cite journal |last1=Krittanawong |first1=C |last2=Qadeer |first2=YK |last3=Hayes |first3=RB |last4=Wang |first4=Z |last5=Thurston |first5=GD |last6=Virani |first6=S |last7=Lavie |first7=CJ |title=PM(2.5) and cardiovascular diseases: State-of-the-Art review. |journal=International Journal of Cardiology. Cardiovascular Risk and Prevention |date=December 2023 |volume=19 |article-number=200217 |doi=10.1016/j.ijcrp.2023.200217 |pmid=37869561 |pmc=10585625 }}</ref> * '''Fine particles''' (PM{{sub|2.5}}), with diameters less than 2.5 micrometers, can penetrate deep into the lungs, reaching the bronchioles and alveoli.<ref name="Hamanaka" /> They are associated with chronic rhinosinusitis,<ref name="Kim" /> respiratory diseases (e.g. asthma and COPD),<ref name="Hamanaka" /> and cardiovascular diseases.<ref name="Krittanawong" /> * '''Ultrafine particles''' (PM{{sub|0.1}}), with diameters less than 0.1 micrometers (100 nanometers), can enter the bloodstream and reach other organs, including the heart and brain.<ref>{{cite journal |last1=Hong |first1=G |last2=Jee |first2=YK |title=Special issue on ultrafine particles: where are they from and how do they affect us? |journal=Experimental & Molecular Medicine |date=March 2020 |volume=52 |issue=3 |pages=309–310 |doi=10.1038/s12276-020-0395-z |pmid=32203099 |pmc=7156368 }}</ref> Ultrafine particles contribute to health issues including neurodegenerative diseases (e.g. Alzheimer's)<ref name="Gong" /><ref name="Air Pollution and Alzheimer's Disea" /> and cardiovascular diseases (e.g. atherosclerosis and increased risk of heart attacks).<ref name="Krittanawong" /><ref name="Liang" /> {| class="wikitable" |+ !Particle Size !Deposition Region |- |>10 μm |Nose/throat |- |2.5–10 μm |Bronchi |- |<2.5 μm |bronchioles/Alveoli |- |<0.1 μm |Blood stream |}

===== Threshold Concentrations and Guidelines ===== The World Health Organization (WHO) provides guidelines to limit exposure.<ref name="who-9789240034228">{{cite book |title=WHO global air quality guidelines: particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide |date=2021 |publisher=World Health Organization |isbn=978-92-4-003422-8 |hdl=10665/345329 |hdl-access=free |page=136}}</ref> * PM{{sub|10}}: Annual mean not to exceed 15 μg/m3; 24-hour mean not to exceed 45 μg/m3.<ref name="who-9789240034228" /> * PM{{sub|2.5}}: Annual mean not to exceed 5 μg/m3; 24-hour mean not to exceed 15 μg/m3.<ref name="who-9789240034228" /> * Exposure above these levels increases the risk of adverse health effects.<ref name="who-9789240034228" /> An examination of PM2.5 concentrations using data from 2000–2019 showed that almost all land areas and populations globally are exposed to PM2.5 at levels above the WHO's 2021 recommended guidelines.<ref name="Yu2023" />

====Shape==== When particulate matter is described in terms of its diameter, as PM{{sub|10}} or PM2.5, particles are assumed to have a idealized spherical shape. The actual shape of particles from different sources (e.g. ashes, soot, paint, glass, plastic and fibres) can vary widely. The table below lists the colors and shapes of some common atmospheric particulates:<ref>{{cite journal |last1=Liu |first1=Jia |last2=Zhang |first2=Yongming |last3=Zhang |first3=Qixing |last4=Wang |first4=Jinjun |title=Scattering Matrix for Typical Urban Anthropogenic Origin Cement Dust and Discrimination of Representative Atmospheric Particulates |journal=Journal of Geophysical Research: Atmospheres |date=27 March 2018 |volume=123 |issue=6 |pages=3159–3174 |doi=10.1002/2018JD028288 |bibcode=2018JGRD..123.3159L }}</ref><ref name="Nasry">{{cite journal |last1=Nasry |first1=Oumaima |last2=Samaouali |first2=Abderrahim |last3=Belarouf |first3=Sara |last4=Moufakkir |first4=Abdelkrim |last5=Sghiouri El Idrissi |first5=Hanane |last6=Soulami |first6=Houda |last7=El Rhaffari |first7=Younes |last8=Hraita |first8=Mohamed |last9=Fertahi |first9=Saïf Ed Dîn |last10=Hafidi-Alaoui |first10=Adil |title=Thermophysical Properties of Cement Mortar Containing Waste Glass Powder |journal=Crystals |date=27 April 2021 |volume=11 |issue=5 |page=488 |doi=10.3390/cryst11050488 |doi-access=free |bibcode=2021Cryst..11..488N |language=en |issn=2073-4352}}</ref> {| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;" ! Type of particulate !! Color !! Shape |- | Portland cement || Gray || Irregular |- | Smolder smoke || White || Spherical |- | Soot || Black || Fractal aggregate |- | Water droplets || White || Spherical |- | Loess || Yellow Brown || Irregular |- | Lokon volcanic ash || Dark Brown || Irregular |- | Sahara sand (Libya) || Brown || Irregular |}

Irregularly shaped particles are more likely to be deposited in airways than spherical ones of similar size.<ref name="Saha"/> Some particles are brittle and can break into smaller pieces. Those with sharp edges or longer needle-like shapes (e.g. asbestos fibres) are more likely to abrade tissues and lodge in the lungs.<ref name="Mack"/><ref name="Fatima">{{cite journal |last1=Fatima |first1=Sadaf |last2=Mishra |first2=Sumit Kumar |last3=Kumar |first3=Uma |last4=Ahlawat |first4=Ajit |last5=Dabodiya |first5=Tulsi Satyavir |last6=Khosla |first6=Dheeraj |title=Role of morphology and chemical composition of PM for particle deposition in human respiratory system: A case study over megacity-Delhi |journal=Urban Climate |date=1 January 2023 |volume=47 |article-number=101344 |doi=10.1016/j.uclim.2022.101344 |bibcode=2023UrbCl..4701344F |issn=2212-0955}}</ref><ref name="Isa">{{cite journal |last1=Isa |first1=Valerio |last2=Saliu |first2=Francesco |last3=Becchi |first3=Alessandro |last4=Spadaccino |first4=Giuseppina |last5=Quinto |first5=Maurizio |last6=Veronelli |first6=Maurizio |last7=Lasagni |first7=Marina |last8=Galli |first8=Paolo |last9=Lavorano |first9=Silvia |title=Impacts of microplastics on reef-building corals: Disentangling the contribution of the chain scission products released by weathering |journal=Science of the Total Environment |date=1 May 2025 |volume=975 |article-number=179239 |doi=10.1016/j.scitotenv.2025.179239 |pmid=40179749 |bibcode=2025ScTEn.97579239I |url=https://www.sciencedirect.com/science/article/pii/S0048969725008745 |issn=0048-9697}}</ref><ref>{{cite book |title=Asbestos: Selected Cancers |date=2006 |publisher=National Academies Press (US) |url=https://www.ncbi.nlm.nih.gov/books/NBK20329/ |language=en |chapter=Exposure and Disposition}}</ref> Geometrically angular shapes have more surface area than rounder shapes, increasing the area available for binding to other substances, which can increase toxicity.<ref name="Fatima"/> Chemical composition can affect interactions with lung tissue and respiratory fluids and influence whether a particle will stick to a surface.<ref name="Saha"/> All of these factors can affect the ways in which particles are inhaled, deposited, cleared, and interact within the respiratory system.<ref name="Mack"/><ref name="Fatima"/>

{{Gallery | title =Scanning electronic microscopy of particulates | align =center | footer = | style = | state = | height = | width =800px | File:Scanning electron microscopy of glass powder.jpg | Scanning electron microscopy of glass powder originated from glass bottles<ref name="Nasry"/> | File:Scanning electron microscopy of cement.jpg | Scanning electron microscopy of cement<ref name="Nasry"/> | File:Scanning electron microscopy of mortar glass powder.jpg | Scanning electron microscopy of mortar glass powder (10%) which seems to have fibre-like structure<ref name="Nasry"/> | File:Chrysotile SEM photo.jpg | Scanning electron microscopy of white asbestos with needle-like shape fibre }}

==== Solubility ==== Particulates vary in chemical composition, containing both soluble and insoluble materials.<ref name="Kelly"/> Particle size, shape, and stickiness can change due to a particle's ability to absorb moisture from its surroundings, in outdoor or indoor air or within the respiratory system.<ref name="ZhangL2021"/> In the lungs, uptake, clearance, retention, and systemic distribution of particulate matter (in the form of gases, vapors, particles or droplets) is highly complex and involves a variety of mechanisms in different areas of the respiratory system.<ref name="Nowak">{{cite journal |last1=Nowak |first1=Norman |last2=Escher |first2=Sylvia E. |last3=Schwarz |first3=Katharina |title=A Unified Whole Lung PBK Model for Inhalational Uptake of Gases and Aerosols in Men |journal=CPT: Pharmacometrics & Systems Pharmacology |date=December 2025 |volume=14 |issue=12 |pages=2173–2185 |doi=10.1002/psp4.70117 |pmid=41045258 |pmc=12706406 |language=en |issn=2163-8306}}</ref>

Respiration and diffusion bring particulate matter into the airways, where particles can be deposited onto airway surfaces such as epithelial tissue and dissolved into the bronchial and pulmonary circulation. Particles that are deposited on airway surfaces can be cleared through respiration, move to other locations within the respiratory tract, or remain trapped and cause irritation or toxicity. From the respiratory system, particulate matter can travel through veins and arteries to the heart, brain, muscle, skin, kidneys, gastrointestinal tract, spleen, liver, bone, and fat.<ref name="Nowak"/>

Solubility is important in determining the site and extent of absorption of inhaled gases and vapors. Particles with high solubility in lung fluid are either rapidly absorbed through the alveolar epithelium or removed by mucociliary clearance in the upper airways. Particles are also removed by alveolar macrophages in the pulmonary region.<ref name="Nowak"/> The behavior of particulates also can be affected by meteorological conditions. Absorption is dependent upon air flow rates and the partial pressure of the gases in the inspired air.<ref name="Nagy" /><ref name="Mack" /> Inhalation also depends upon the breathing rate and breathing mode of the subject.<ref>{{cite journal |last1=Cao |first1=W |last2=Sun |first2=B |last3=Zhao |first3=Y |last4=Shi |first4=Q |last5=Wang |first5=Y |title=Study on the transmission route of virus aerosol particles and control technology of air conditioning in the enclosed space. |journal=European Physical Journal Plus |date=2021 |volume=136 |issue=10 |page=1049 |doi=10.1140/epjp/s13360-021-02058-8 |pmid=34692366 |pmc=8526525 |bibcode=2021EPJP..136.1049C }}</ref><ref>{{cite journal |last1=Elkama |first1=A |last2=Şüküroğlu |first2=AA |last3=Çakmak |first3=G |title=Exposure to particulate matter: a brief review with a focus on cardiovascular effects, children, and research conducted in Turkey. |journal=Arhiv Za Higijenu Rada I Toksikologiju |date=30 December 2021 |volume=72 |issue=4 |pages=244–253 |doi=10.2478/aiht-2021-72-3563 |pmid=34985835 |pmc=8785112 }}</ref>

The fate of a specific contaminant is dependent upon the form in which it exists (aerosol or particle). Water-soluble organic compounds include alcohols, carboxylic acids, keto acids, phenols and hydroxylamines, while insoluble organic compounds include aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and polycyclic aromatic ketones.<ref name="LiB2023">{{cite journal |last1=Li |first1=B |last2=Ma |first2=Y |last3=Zhou |first3=Y |last4=Chai |first4=E |title=Research progress of different components of PM(2.5) and ischemic stroke. |journal=Scientific Reports |date=25 September 2023 |volume=13 |issue=1 |page=15965 |doi=10.1038/s41598-023-43119-5 |pmid=37749193 |pmc=10519985 }}</ref> Water-soluble inorganic ions account for 30% to 50% of PM2.5 mass concentration, with sulfate, nitrate, and ammonium salts being the most abundant.<ref name="LiB2023" />

=== Mechanisms of health effects === The upper respiratory tract (URT) is the main point where particulate matter can enter the human body.<ref name="Arca" /> Due to its size, PM10 tends to be limited to the upper airways, including the nose, throat, and bronchi. PM2.5 and PM0.1 are smaller and may travel deeper into the lungs, entering small airways and reaching the alveoli. As a result, they cause different and greater harms to health.<ref name="Hamanaka" />

{{external media | width = 210px | float = right | headerimage= 200px | video1 = [https://www.youtube.com/watch?v=mZvzl8KH6iI "Alveoli: Gas Exchange"], Science Sauce.}} Alveoli are air sacs deep in the lungs, where oxygen from inhaled air enters the bloodstream and carbon dioxide is released. The walls of the alveoli are formed of epithelial cells, which are surrounded by capillaries of the bloodstream. This thin air-blood barrier supports diffusion between the lungs and the bloodstream.<ref>{{cite journal |last1=Brandt |first1=Josiah P. |last2=Mandiga |first2=Pujyitha |title=Histology, Alveolar Cells |url=https://www.ncbi.nlm.nih.gov/books/NBK557542/ |website=StatPearls |publisher=StatPearls Publishing |date=2026 |pmid=32491474 }}</ref> Alveoli have a fluid-coated surface that helps them to inflate properly and maintain their shape.<ref>{{cite journal |last1=Knudsen |first1=L |last2=Ochs |first2=M |title=The micromechanics of lung alveoli: structure and function of surfactant and tissue components. |journal=Histochemistry and Cell Biology |date=December 2018 |volume=150 |issue=6 |pages=661–676 |doi=10.1007/s00418-018-1747-9 |pmid=30390118 |pmc=6267411 }}</ref>

thumb | right |200px|Alveolar macrophages (blue/green) in alveoli Immune cells called macrophages protect tissues through innate immune responses, detecting, surrounding and digesting inhaled particulate matter and cellular debris.<ref name=":11">{{cite journal |last1=Li |first1=CH |last2=Tsai |first2=ML |last3=Chiou |first3=HC |last4=Lin |first4=YC |last5=Liao |first5=WT |last6=Hung |first6=CH |title=Role of Macrophages in Air Pollution Exposure Related Asthma. |journal=International Journal of Molecular Sciences |date=15 October 2022 |volume=23 |issue=20 |article-number=12337 |doi=10.3390/ijms232012337 |doi-access=free |pmid=36293195 |pmc=9603963 }}</ref> Alveolar macrophages adapt to environmental cues by managing inflammatory responses. They react in ways that can be either pro-inflammatory (M1) to fight infections or anti-inflammatory (M2) to promote tissue repair. They also manage adaptive immune responses involving future recognition and response to harmful substances. This can lead to either increased immune response or increased tolerance of challenges. Alveolar macrophages are crucial in maintaining a stable environment to support gas exchange in the alveoli, attempting to balance attacks on pathogens with prevention of cell damage.<ref name="Arca" /><ref name=":11" />

[[File: Pył zawieszony Komunikat o jakości powietrza w Katowicach 7.10.2011 godz. 9.10.JPG|thumb|Air quality information on PM10 displayed in Katowice, Poland]] Particulate matter can carry toxic substances and harmful microbes into the lungs and upset the balance of beneficial microbes and cellular activities.<ref name="Arca" /> Both PM10 and PM2.5 trigger acute inflammatory responses involving release of proinflammatory cytokines.<ref name="Arca" /><ref name=":11" /> They also induce production of reactive oxygen species (ROS) which cause oxidative stress and damage cells, triggering further inflammation.<ref name=":11" /> They can interfere with the work of macrophages in managing detection and removal of particulate matter, inflammation, tissue repair, and adaptive immune responses.<ref name="Arca" /><ref name=":11" /><ref>{{cite journal |last1=Patel |first1=B |last2=Gupta |first2=N |last3=Ahsan |first3=F |title=Barriers that Inhaled Particles Encounter. |journal=Journal of Aerosol Medicine and Pulmonary Drug Delivery |date=October 2024 |volume=37 |issue=5 |pages=299–306 |doi=10.1089/jamp.2024.27498.bp |pmid=39388690 |pmc=11520697 }}</ref>

PM10 is related to increases in upper respiratory tract symptoms such as runny nose, cough and sneezing. It increases susceptibility to respiratory infections and inflammatory respiratory disorders of the nasal cavity (e.g. allergic rhinitis and chronic rhinosinusitis).<ref name="Arca" /><ref name="Ratajczak">{{cite journal |last1=Ratajczak |first1=A |last2=Badyda |first2=A |last3=Czechowski |first3=PO |last4=Czarnecki |first4=A |last5=Dubrawski |first5=M |last6=Feleszko |first6=W |title=Air Pollution Increases the Incidence of Upper Respiratory Tract Symptoms among Polish Children. |journal=Journal of Clinical Medicine |date=16 May 2021 |volume=10 |issue=10 |page=2150 |doi=10.3390/jcm10102150 |doi-access=free |pmid=34065636 |pmc=8156299 }}</ref>

Fine particulate matter (PM2.5 and ultrafine particulates) can reach the lower lungs and alveoli.<ref name="Arca" /><ref name="Krittanawong" /><ref name="Schraufnagel2020" /> In the lower airways, particles are retained longer and cause more damage.<ref name=":11" /> In the upper respiratory tract, PM2.5 is linked to damage to airway epithelial cells and disruption of their functions. In the lower respiratory tract it can destroy alveolar epithelial cells.<ref name="Ma"/> Mechanisms by which PM2.5 causes harms include oxidative stress, inflammatory responses, cytokine release, DNA damage, changes in gene expression, immunotoxicity, and apoptosis.<ref name="Sangkham">{{cite journal |last1=Sangkham |first1=S |last2=Phairuang |first2=W |last3=Sherchan |first3=SP |last4=Pansakun |first4=N |last5=Munkong |first5=N |last6=Sarndhong |first6=K |last7=Islam |first7=MA |last8=Sakunkoo |first8=P |title=An update on adverse health effects from exposure to PM2.5 |journal=Environmental Advances |date=1 December 2024 |volume=18 |article-number=100603 |doi=10.1016/j.envadv.2024.100603 |url=https://www.sciencedirect.com/science/article/pii/S2666765724001212 |issn=2666-7657}}</ref> Long-term damage to lung tissues can result from accelerated cell death, tissue scarring (fibrosis), reduced lung elasticity, and structural remodeling.<ref>{{cite journal |last1=Grafanaki |first1=K |last2=Maniatis |first2=A |last3=Sotiropoulou |first3=V |last4=Pasmatzi |first4=E |last5=Tzouvelekis |first5=A |title=Fibrotic Disease of the Skin and Lung: Shared Pathways, Environmental Drivers, and Therapeutic Opportunities in a Changing Climate. |journal=International Journal of Molecular Sciences |date=29 August 2025 |volume=26 |issue=17 |page=8394 |doi=10.3390/ijms26178394 |doi-access=free |pmid=40943318 |pmc=12428245 }}</ref>

Some PM2.5 and ultrafine particulates can cross the air-blood barrier to enter the bloodstream. From there, they can travel throughout the body.<ref name="Arca" /><ref name="Krittanawong" /><ref name="Schraufnagel2020" /> Systemic harms occur as a result of the movement of particles into the cardiovascular system and on to other organs including the brain.<ref name="Krittanawong" /><ref name="Schraufnagel2020" /> Particulates may cause tissue damage directly in specific organs, or indirectly as a result of systemic inflammation.<ref name="Balmes">{{cite journal |last1=Schraufnagel |first1=Dean E. |last2=Balmes |first2=John R. |last3=Cowl |first3=Clayton T. |last4=De Matteis |first4=Sara |last5=Jung |first5=Soon-Hee |last6=Mortimer |first6=Kevin |last7=Perez-Padilla |first7=Rogelio |last8=Rice |first8=Mary B. |last9=Riojas-Rodriguez |first9=Horacio |last10=Sood |first10=Akshay |last11=Thurston |first11=George D. |last12=To |first12=Teresa |last13=Vanker |first13=Anessa |last14=Wuebbles |first14=Donald J. |title=Air Pollution and Noncommunicable Diseases |journal=Chest |date=February 2019 |volume=155 |issue=2 |pages=409–416 |doi=10.1016/j.chest.2018.10.042 |pmid=30419235 |pmc=6904855 }}</ref>

Particulate matter that is caught by the mucociliary system and removed from the lungs can be swallowed and reach the intestines, affecting the gastrointestinal system. Particulate matter has been linked to inflammatory bowel disease (IBD), colorectal cancer, appendicitis, and chronic kidney and liver diseases.<ref name="Arca" />

Regarding specific contaminants, water-soluble inorganic ions like sulfate, nitrate, and ammonium salts can penetrate deep into the lungs and travel through the bloodstream. Sulfate has been linked to platelet aggregation and vascular endothelial cell damage. Ammonium salts stimulate the growth of blood vessel wall cells and blood vessel narrowing through chronic inflammation and oxidative stress. All three are linked to increased risk of ischemic stroke and other health problems. They affect health through mechanisms including chronic inflammation, oxidative stress, platelet aggregation and vascular endothelial cell injury. Carbon-containing components affect accelerated plaque formation, atherosclerosis, cardiac autonomic function, and platelet aggregation. Inorganic elements are involved in neural disturbances, genetic mutations, and disruption of homeostasis and biological processes.<ref name="LiB2023" />

Toxic components in PM2.5 can include polycyclic aromatic hydrocarbons (PAHs), aliphatic chlorinated hydrocarbons, oxygen-containing organic compounds such as ketones and quinones, and heavy metals like arsenic, cadmium, chromium, copper, lead, nickel, and zinc.<ref name="Ma">{{cite journal |last1=Ma |first1=J |last2=Chiu |first2=YF |last3=Kao |first3=CC |last4=Chuang |first4=CN |last5=Chen |first5=CY |last6=Lai |first6=CH |last7=Kuo |first7=ML |title=Fine particulate matter manipulates immune response to exacerbate microbial pathogenesis in the respiratory tract. |journal=European Respiratory Review |date=July 2024 |volume=33 |issue=173 |doi=10.1183/16000617.0259-2023 |pmid=39231594 |pmc=11372469 }}</ref> Toxic components in PM2.5 disrupt the activity of macrophages and are associated with the development of cancers.<ref name="Ma"/> Heavy metals disrupt cellular activity and increase the production of reactive oxygen species (ROS), while organic pollutants like PAHs activate the aryl hydrocarbon receptor (AhR) pathway inducing vascular toxicity. When these components of particulate matter occur together, they act synergistically to cause even greater cellular damage.<ref name="Ho">{{cite journal |last1=Ho |first1=CC |last2=Wu |first2=WT |last3=Lin |first3=YJ |last4=Weng |first4=CY |last5=Tsai |first5=MH |last6=Tsai |first6=HT |last7=Chen |first7=YC |last8=Yet |first8=SF |last9=Lin |first9=P |title=Aryl hydrocarbon receptor activation-mediated vascular toxicity of ambient fine particulate matter: contribution of polycyclic aromatic hydrocarbons and osteopontin as a biomarker. |journal=Particle and Fibre Toxicology |date=23 June 2022 |volume=19 |issue=1 |page=43 |doi=10.1186/s12989-022-00482-x |doi-access=free |pmid=35739584 |pmc=9219152 |bibcode=2022PFTox..19...43H }}</ref><ref name="Yu" />

Increased levels of fine particles in the air as a result of anthropogenic particulate air pollution are "consistently and independently related to the most serious effects".<ref name="Lancet71013">{{cite journal |display-authors=6 |last1=Raaschou-Nielsen |first1=Ole |last2=Andersen |first2=Zorana J |last3=Beelen |first3=Rob |last4=Samoli |first4=Evangelia |last5=Stafoggia |first5=Massimo |last6=Weinmayr |first6=Gudrun |last7=Hoffmann |first7=Barbara |last8=Fischer |first8=Paul |last9=Nieuwenhuijsen |first9=Mark J |last10=Brunekreef |first10=Bert |last11=Xun |first11=Wei W |last12=Katsouyanni |first12=Klea |last13=Dimakopoulou |first13=Konstantina |last14=Sommar |first14=Johan |last15=Forsberg |first15=Bertil |last16=Modig |first16=Lars |last17=Oudin |first17=Anna |last18=Oftedal |first18=Bente |last19=Schwarze |first19=Per E |last20=Nafstad |first20=Per |last21=De Faire |first21=Ulf |last22=Pedersen |first22=Nancy L |last23=Östenson |first23=Claes-Göran |last24=Fratiglioni |first24=Laura |last25=Penell |first25=Johanna |last26=Korek |first26=Michal |last27=Pershagen |first27=Göran |last28=Eriksen |first28=Kirsten T |last29=Sørensen |first29=Mette |last30=Tjønneland |first30=Anne |last31=Ellermann |first31=Thomas |last32=Eeftens |first32=Marloes |last33=Peeters |first33=Petra H |last34=Meliefste |first34=Kees |last35=Wang |first35=Meng |last36=Bueno-de-Mesquita |first36=Bas |last37=Key |first37=Timothy J |last38=de Hoogh |first38=Kees |last39=Concin |first39=Hans |last40=Nagel |first40=Gabriele |last41=Vilier |first41=Alice |last42=Grioni |first42=Sara |last43=Krogh |first43=Vittorio |last44=Tsai |first44=Ming-Yi |last45=Ricceri |first45=Fulvio |last46=Sacerdote |first46=Carlotta |last47=Galassi |first47=Claudia |last48=Migliore |first48=Enrica |last49=Ranzi |first49=Andrea |last50=Cesaroni |first50=Giulia |last51=Badaloni |first51=Chiara |last52=Forastiere |first52=Francesco |last53=Tamayo |first53=Ibon |last54=Amiano |first54=Pilar |last55=Dorronsoro |first55=Miren |last56=Trichopoulou |first56=Antonia |last57=Bamia |first57=Christina |last58=Vineis |first58=Paolo |last59=Hoek |first59=Gerard |title=Air pollution and lung cancer incidence in 17 European cohorts: prospective analyses from the European Study of Cohorts for Air Pollution Effects (ESCAPE) |journal=The Lancet Oncology |date=August 2013 |volume=14 |issue=9 |pages=813–822 |doi=10.1016/S1470-2045(13)70279-1 |pmid=23849838 }}</ref> Quantity and duration of exposure affect processes and outcomes.<ref>{{cite journal |title=Experimental study to quantify airborne particle deposition onto and resuspension from clothing using a fluorescent-tracking method |year=2022 |pmc=8620412 |last1=Ren |first1=J. |last2=Tang |first2=M. |last3=Novoselac |first3=A. |journal=Building and Environment |volume=209 |article-number=108580 |doi=10.1016/j.buildenv.2021.108580 |pmid=34848915 |bibcode=2022BuEnv.20908580R}}</ref><ref>{{cite web |title=地盤工滿身泥衣鞋入茶餐廳網民批成身水泥累慘清潔工: 做死阿姐 |website=香港01 |date=20 July 2023 |url=https://www.hk01.com/熱爆話題/919862/地盤工滿身泥衣鞋入茶餐廳-網民批成身水泥累慘清潔工-做死阿姐 |language=zh |access-date=14 August 2023}}</ref> Adverse effects may occur at exposure levels lower than those recommended in published air quality standards.<ref name="Balmes" /><ref>{{cite news |last1=Carrington |first1=Damian |last2=McMullan |first2=Lydia |last3=Blight |first3=Garry |last4=Roberts |first4=Simon |last5=Hulley-Jones |first5=Frank |title=Revealed: air pollution may be damaging 'every organ in the body' |url=https://www.theguardian.com/environment/ng-interactive/2019/may/17/air-pollution-may-be-damaging-every-organ-and-cell-in-the-body-finds-global-review |work=The Guardian |date=17 May 2019 }}</ref>

=== Impacts on health === Exposure to particulate matter, a modifiable risk factor, is linked to diseases throughout the body. It affects the respiratory system (asthma, chronic obstructive pulmonary disease, lung cancer, pulmonary fibrosis, pneumonia, acute respiratory distress syndrome<ref name="Hamanaka" /> rhinosinusitis<ref name="Kim" /> and silicosis<ref>{{Cite web| url = https://www.ccohs.ca/oshanswers/diseases/silicosis.html| title = Silicosis, OSH Answers Fact Sheets| date = 13 June 2023| access-date = 4 February 2023| archive-date = 4 February 2023| archive-url = https://web.archive.org/web/20230204050559/https://www.ccohs.ca/oshanswers/diseases/silicosis.html| url-status = live}}</ref>), the cardiovascular system (heart attacks, hypertension,<ref>{{cite journal |last1=Che |first1=L |last2=Wang |first2=Z |title=Environmental pollution and its impact on hypertension: a review. |journal=Frontiers in Public Health |date=2025 |volume=13 |article-number=1637703 |doi=10.3389/fpubh.2025.1637703 |doi-access=free |pmid=41098746 |pmc=12518403 }}</ref><ref>{{Cite web |date=9 October 2025 |author-first=Rasmus |author-last=Cloes|title=Clean air protects children from high blood pressure and elevated diabetes markers |url=https://www.bips-institut.de/en/media/press/single-view/saubere-luft-schuetzt-kinder-vor-hohem-blutdruck-und-erhoehten-diabetes-markern.html |access-date=5 November 2025 |website=www.bips-institut.de |language=en-GB}}</ref> arrhythmias, and atherosclerosis),<ref name="Krittanawong" /><ref name="Bhatnagar">{{cite journal |last1=Bhatnagar |first1=A |title=Cardiovascular Effects of Particulate Air Pollution. |journal=Annual Review of Medicine |date=27 January 2022 |volume=73 |pages=393–406 |doi=10.1146/annurev-med-042220-011549 |pmid=34644154 |pmc=10132287 }}</ref> the nervous system (cognitive decline, neurodegenerative diseases such as Alzheimer's disease<ref name="Air Pollution and Alzheimer's Disea">{{cite journal |last1=Fu |first1=Pengfei |last2=Yung |first2=Ken Kin Lam |title=Air Pollution and Alzheimer's Disease: A Systematic Review and Meta-Analysis |journal=Journal of Alzheimer's Disease |date=15 September 2020 |volume=77 |issue=2 |pages=701–714 |doi=10.3233/JAD-200483 |pmid=32741830 }}</ref><ref name="Fine particulate matter is a potent">{{cite journal |last1=Tsai |first1=Tsung-Lin |last2=Lin |first2=Yu-Ting |last3=Hwang |first3=Bing-Fang |last4=Nakayama |first4=Shoji F. |last5=Tsai |first5=Chon-Haw |last6=Sun |first6=Xian-Liang |last7=Ma |first7=Chaochen |last8=Jung |first8=Chau-Ren |title=Fine particulate matter is a potential determinant of Alzheimer's disease: A systemic review and meta-analysis |journal=Environmental Research |date=October 2019 |volume=177 |article-number=108638 |doi=10.1016/j.envres.2019.108638 |pmid=31421449 |bibcode=2019ER....17708638T }}</ref>, mental disorders,<ref name="Braithwaite">{{cite journal |last1=Braithwaite |first1=Isobel |last2=Zhang |first2=Shuo |last3=Kirkbride |first3=James B. |last4=Osborn |first4=David P. J. |last5=Hayes |first5=Joseph F. |title=Air Pollution (Particulate Matter) Exposure and Associations with Depression, Anxiety, Bipolar, Psychosis and Suicide Risk: A Systematic Review and Meta-Analysis |journal=Environmental Health Perspectives |date=December 2019 |volume=127 |issue=12 |page=126002 |doi=10.1289/EHP4595 |pmid=31850801 |pmc=6957283 |bibcode=2019EnvHP.127l6002B }}</ref><ref name="economic">{{cite journal |last1=Lu |first1=Jackson G |title=Air pollution: A systematic review of its psychological, economic, and social effects |journal=Current Opinion in Psychology |date=April 2020 |volume=32 |pages=52–65 |doi=10.1016/j.copsyc.2019.06.024 |pmid=31557706 }}</ref><ref name="Liu2021">{{cite journal |last1=Liu |first1=Qisijing |last2=Wang |first2=Wanzhou |last3=Gu |first3=Xuelin |last4=Deng |first4=Furong |last5=Wang |first5=Xueqin |last6=Lin |first6=Hualiang |last7=Guo |first7=Xinbiao |last8=Wu |first8=Shaowei |title=Association between particulate matter air pollution and risk of depression and suicide: a systematic review and meta-analysis |journal=Environmental Science and Pollution Research |date=February 2021 |volume=28 |issue=8 |pages=9029–9049 |doi=10.1007/s11356-021-12357-3 |pmid=33481201 |bibcode=2021ESPR...28.9029L }}</ref>), the gastrointestinal system (inflammatory bowel disease, colorectal cancer, appendicitis, kidney and liver diseases),<ref name="Yu" /><ref name="Arca" /> and metabolic system (diabetes,<ref name="Liviero">{{cite journal |last1=Liviero |first1=F |last2=Pavanello |first2=S |title=Epidemiological and mechanistic links between PM(2.5) exposure and type 2 diabetes: focus on the TRPV1 receptor. |journal=Frontiers in Endocrinology |date=2025 |volume=16 |article-number=1653375 |doi=10.3389/fendo.2025.1653375 |doi-access=free |pmid=40964166 |pmc=12436132 }}</ref><ref name="Jiang">{{cite journal |last1=Jiang |first1=W |last2=Zhou |first2=H |last3=Xu |first3=G |last4=Zhang |first4=M |last5=Tung |first5=TH |last6=Luo |first6=C |title=The association between air pollution and three types of diabetes: An umbrella review of systematic reviews and meta-analyses. |journal=Ecotoxicology and Environmental Safety |date=1 April 2025 |volume=294 |article-number=118080 |doi=10.1016/j.ecoenv.2025.118080 |pmid=40118013 |bibcode=2025EcoES.29418080J }}</ref> metabolic syndrome<ref name="Kim2025">{{cite journal |last1=Kim |first1=HJ |last2=Hwang |first2=J |last3=Park |first3=JH |title=Long-Term Exposure to Ambient Air Pollution and Metabolic Syndrome and Its Components. |journal=Journal of Obesity & Metabolic Syndrome |date=30 April 2025 |volume=34 |issue=2 |pages=91–104 |doi=10.7570/jomes24036 |pmid=40090381 |pmc=12067007 }}</ref>, breast cancer<ref name="Wang2025">{{cite journal |last1=Wang |first1=Ruohan |last2=Wang |first2=Peihan |last3=Zhou |first3=Yongkang |last4=Wang |first4=Yinan |last5=Xu |first5=Chengdong |last6=Wang |first6=Zhenbo |last7=Wang |first7=Wei |title=Association between long-term ambient air pollution exposure and the incidence of breast cancer: A meta-analysis based on updated evidence |journal=Ecotoxicology and Environmental Safety |date=1 January 2025 |volume=289 |article-number=117472 |doi=10.1016/j.ecoenv.2024.117472 |pmid=39667318 |bibcode=2025EcoES.28917472W |url=https://doi.org/10.1016/j.ecoenv.2024.117472 |issn=0147-6513}}</ref>), and the reproductive system.<ref name=":12">{{cite journal |last1=Tao |first1=Q |last2=Zhao |first2=Z |last3=Yang |first3=R |last4=Li |first4=Q |last5=Qiao |first5=J |title=Fine particulate matter and ovarian health: A review of emerging risks. |journal=Heliyon |date=30 November 2024 |volume=10 |issue=22 |article-number=e40503 |doi=10.1016/j.heliyon.2024.e40503 |doi-access=free |pmid=39650185 |pmc=11625118 |bibcode=2024Heliy..1040503T }}</ref><ref name=":13">{{cite journal |last1=Wang |first1=L |last2=Luo |first2=D |last3=Liu |first3=X |last4=Zhu |first4=J |last5=Wang |first5=F |last6=Li |first6=B |last7=Li |first7=L |title=Effects of PM(2.5) exposure on reproductive system and its mechanisms. |journal=Chemosphere |date=February 2021 |volume=264 |issue=Pt 1 |article-number=128436 |doi=10.1016/j.chemosphere.2020.128436 |pmid=33032215 |bibcode=2021Chmsp.26428436W }}</ref><ref name=":14">{{cite journal |last1=Ward |first1=G |last2=Correia Watts |first2=MP |last3=Hansson |first3=SR |title=The unintended consequences of modernity: Pollution and its effect on reproductive, maternal and fetal health |journal=Pregnancy Hypertension |date=1 June 2025 |volume=40 |article-number=101204 |doi=10.1016/j.preghy.2025.101204 |pmid=40015200 |url=https://www.sciencedirect.com/science/article/pii/S2210778925000200 |issn=2210-7789}}</ref> The effects of particulate matter have been studied in connection with premature delivery,<ref name=":15">{{cite journal |last1=Guo |first1=B |last2=Jiang |first2=X |title=Association between atmospheric particulate matter pollution during pregnancy and premature birth in China: a meta-analysis. |journal=Frontiers in Public Health |date=2025 |volume=13 |article-number=1474134 |doi=10.3389/fpubh.2025.1474134 |doi-access=free |pmid=39916718 |pmc=11798961 |bibcode=2025FrPH...1374134G }}</ref> birth defects, low birth weight,<ref name=":16">{{cite journal |last1=Song |first1=S |last2=Gao |first2=Z |last3=Zhang |first3=X |last4=Zhao |first4=X |last5=Chang |first5=H |last6=Zhang |first6=J |last7=Yu |first7=Z |last8=Huang |first8=C |last9=Zhang |first9=H |title=Ambient fine particulate matter and pregnancy outcomes: An umbrella review. |journal=Environmental Research |date=15 October 2023 |volume=235 |article-number=116652 |doi=10.1016/j.envres.2023.116652 |pmid=37451569 |bibcode=2023ER....23516652S }}</ref><ref name=":7" /> and developmental disorders.<ref>{{cite journal |last1=Lin |first1=LZ |last2=Zhan |first2=XL |last3=Jin |first3=CY |last4=Liang |first4=JH |last5=Jing |first5=J |last6=Dong |first6=GH |title=The epidemiological evidence linking exposure to ambient particulate matter with neurodevelopmental disorders: A systematic review and meta-analysis. |journal=Environmental Research |date=June 2022 |volume=209 |article-number=112876 |doi=10.1016/j.envres.2022.112876 |pmid=35134379 |bibcode=2022ER....20912876L }}</ref><ref name="Maternal exposure to air pollution">{{cite journal |last1=Chun |first1=HeeKyoung |last2=Leung |first2=Cheryl |last3=Wen |first3=Shi Wu |last4=McDonald |first4=Judy |last5=Shin |first5=Hwashin H. |title=Maternal exposure to air pollution and risk of autism in children: A systematic review and meta-analysis |journal=Environmental Pollution |date=January 2020 |volume=256 |article-number=113307 |doi=10.1016/j.envpol.2019.113307 |pmid=31733973 |doi-access=free |bibcode=2020EPoll.25613307C }}</ref> Air pollution has also been linked to a range of psychosocial problems including violence and crime.<ref name="economic" /><ref name="Berman">{{cite journal |last1=Berman |first1=JD |last2=Burkhardt |first2=J |last3=Bayham |first3=J |last4=Carter |first4=E |last5=Wilson |first5=A |title=Acute Air Pollution Exposure and the Risk of Violent Behavior in the United States. |journal=Epidemiology (Cambridge, Mass.) |date=November 2019 |volume=30 |issue=6 |pages=799–806 |doi=10.1097/EDE.0000000000001085 |pmid=31430264}}</ref>

==== Death ==== {{See also|Harvard Six Cities study}} thumb|upright=1.3|Deaths from air pollution compared to other common causes in Indonesia, USA, India and China in 2019 According to the State of Global Air 2025 report, air pollution (including particulate matter from both outdoor and household sources) is the leading environmental risk factor for death world-wide.<ref name="SOGA2025" /><ref name=":10" /> The association between particulate pollution and large numbers of premature deaths and other health problems was first demonstrated in the early 1970s<ref name="lave">{{cite journal | last1 = Lave | first1 = Lester B.|author1-link=Lester Lave| last2 = Seskin | first2 = Eugene P. | title = An Analysis of the Association between U.S. Mortality and Air Pollution | journal = Journal of the American Statistical Association | date = June 1973 | volume = 68 | issue = 342 | pages = 284–290 | doi = 10.1080/01621459.1973.10482421 | pmid = | url = }}</ref> and has been reproduced many times since. Both short-term exposure (hours to a few days)<ref name="Orellano">{{cite journal |last1=Orellano |first1=P |last2=Reynoso |first2=J |last3=Quaranta |first3=N |last4=Bardach |first4=A |last5=Ciapponi |first5=A |title=Short-term exposure to particulate matter (PM(10) and PM(2.5)), nitrogen dioxide (NO(2)), and ozone (O(3)) and all-cause and cause-specific mortality: Systematic review and meta-analysis. |journal=Environment International |date=September 2020 |volume=142 |article-number=105876 |doi=10.1016/j.envint.2020.105876 |pmid=32590284}}</ref> and long-term exposure (months to years) to PM10 and PM2.5 have negative effects.<ref name="Kasdagli">{{cite journal |last1=Orellano |first1=P |last2=Kasdagli |first2=MI |last3=Pérez Velasco |first3=R |last4=Samoli |first4=E |title=Long-Term Exposure to Particulate Matter and Mortality: An Update of the WHO Global Air Quality Guidelines Systematic Review and Meta-Analysis. |journal=International Journal of Public Health |date=2024 |volume=69 |article-number=1607683 |doi=10.3389/ijph.2024.1607683 |doi-access=free |pmid=39399882 |pmc=11466858 }}</ref> Over all causes of mortality, PM2.5 has more severe health effects than PM10.<ref name="Xue" />

In 2023, 7.9 million deaths worldwide (approximately 1 in 8) were attributable to the effects of air pollution. 4.9 million were attributable to outdoor PM2.5 exposure, and another 2.8 million to household exposure.<ref name="SOGA2025" /> Of all pollution-related deaths, 86% overall and 95% of adults over 60 years of age were associated with the development and worsening of noncommunicable diseases such as COPD, dementia, diabetes, heart disease, and lung disease.<ref name=":10">{{cite web |title=New State of Global Air 2025 report shows nearly nine in ten global air pollution deaths are from noncommunicable diseases |author-first=Tom |author-last= Champoux|url=https://www.healtheffects.org/announcements/new-state-global-air-2025-report-shows-nearly-nine-ten-global-air-pollution-deaths-are |website=Health Effects Institute |access-date=7 April 2026 |language=en |date=21 October 2025}}</ref><ref name="SOGA2025">{{Cite book |author=Health Effects Institute |author-link1=Health Effects Institute |url=https://www.stateofglobalair.org/resources/report/state-global-air-report-2025 |title=State of Global Air 2025: A Report on Air Pollution and Its Role in the World's Leading Causes of Death. |author2=Institute for Health Metrics and Evaluation |author-link2=Institute for Health Metrics and Evaluation |author3=NCD Alliance |publisher=Health Effects Institute |year=2025 |location=en |pages=4–5,22 |format= |issn=2578-6873 }}</ref>

The 2021 Global Burden of Disease Study (GBD) reported that outdoor fine particulates with diameter less than 2.5 microns (PM2.5) accounted for 7.83 million deaths and 231.51 million disability-adjusted life-years lost (DALYs) globally in 2021. PM2.5 was identified as a major health risk factor globally.<ref name="GBD2021">{{cite journal |last1=Fang |first1=T |last2=Di |first2=Y |last3=Xu |first3=Y |last4=Shen |first4=N |last5=Fan |first5=H |last6=Hou |first6=S |last7=Li |first7=X |title=Temporal trends of particulate matter pollution and its health burden, 1990-2021, with projections to 2036: a systematic analysis for the global burden of disease study 2021. |journal=Frontiers in Public Health |date=2025 |volume=13 |article-number=1579716 |doi=10.3389/fpubh.2025.1579716 |doi-access=free |pmid=40308905 |pmc=12041061 |bibcode=2025FrPH...1379716F }}</ref>

In 2023, PM2.5 contributed to an estimated 182,000 premature deaths in the European Union. This was a decrease of 57% compared to the effects of PM2.5 in 2005. The decrease is attributed to changes in policies that led to a 38% decline in total emissions of primary PM2.5 between 2005 and 2023.<ref>{{cite web |title=Premature deaths due to exposure to fine particulate matter in Europe |url=https://www.eea.europa.eu/en/analysis/indicators/health-impacts-of-exposure-to |website=European Environment Agency |access-date=7 April 2026 |language=en |date=30 November 2025}}</ref>

In China, passage of the Air Pollution Prevention and Control Action Plan (APPCAP) in 2013 led to a one-third decrease in annual average PM2.5 concentrations and fewer deaths between 2013 and 2017.<ref name="Hamanaka"/><ref name="Wu 122405–122419">{{Cite journal |last=Wu |first=Wenqi |date=2023-11-16 |title=Is air pollution joint prevention and control effective in China—evidence from "Air Pollution Prevention and Control Action Plan" |url=https://link.springer.com/10.1007/s11356-023-30982-y |journal=Environmental Science and Pollution Research |language=en |volume=30 |issue=58 |pages=122405–122419 |doi=10.1007/s11356-023-30982-y |pmid=37971591 |bibcode=2023ESPR...3022405W |issn=1614-7499|url-access=subscription }}</ref> However PM2.5 continues to be a major environmental health risk in China, responsible for 2.27 million deaths and 46.68 million disability-adjusted life years (DALYs) in 2021.<ref>{{cite journal |last1=Fang |first1=T |last2=Xu |first2=Y |last3=Shen |first3=N |last4=Liu |first4=J |last5=Di |first5=Y |last6=Hou |first6=S |title=Trends and projections of PM(2.5)-attributable disease burden in China: a GBD 2021-based analysis. |journal=Frontiers in Public Health |date=2026 |volume=14 |article-number=1684344 |doi=10.3389/fpubh.2026.1684344 |doi-access=free |pmid=41624123 |pmc=12852448 }}</ref>

In the United States, amendments to the Clean Air Act in 1970 resulted in decreases in PM2.5 levels and increases in life expectancy, as was shown by the Harvard Six Cities Study and others.<ref name="Hamanaka"/> However, since 2016, PM2.5 concentrations are no longer decreasing in the U.S.<ref name="Nassau">{{cite journal |last1=Nassau |first1=Racine |last2=Jaeglé |first2=Lyatt |title=Understanding the Recent Stagnation in PM 2.5 Concentrations Across the United States: A Seasonal Composition Perspective |journal=Journal of Geophysical Research: Atmospheres |date=28 June 2025 |volume=130 |issue=12 |article-number=e2024JD042401 |doi=10.1029/2024JD042401 |language=en |issn=2169-897X}}</ref> In 2017, pollution was estimated to account for nearly 197,000 deaths in the United States.<ref name="Lakhani">{{cite news |last1=Lakhani |first1=Nina |title=US among top 10 countries for pollution-related deaths, new study shows |url=https://www.theguardian.com/environment/2019/dec/18/us-top-10-countries-pollution-related-deaths-study |access-date=7 April 2026 |work=The Guardian |date=18 December 2019}}</ref> A 2022 study in ''GeoHealth'' concluded that eliminating energy-related fossil fuel emissions in the United States would prevent {{val|46900|–|59400|fmt=commas}} premature deaths each year and provide {{val|p=$|537|–|678|u=billion}} in benefits from avoided PM{{sub|2.5}}-related illness and death.<ref name="GeoHealth_20220516">{{cite journal |last1=Mailloux |first1=Nicholas A. |last2=Abel |first2=David W. |last3=Holloway |first3=Tracey |last4=Patz |first4=Jonathan A. |title=Nationwide and Regional PM{{sub|2.5}}-Related Air Quality Health Benefits From the Removal of Energy-Related Emissions in the United States |journal=GeoHealth |volume=6 |issue=5 |date=16 May 2022 |article-number=e2022GH000603 |doi=10.1029/2022GH000603 |pmid=35599962 |pmc=9109601 |bibcode=2022GHeal...6..603M }}</ref>

There are interactions between particulate matter, exercise, and mortality. The health benefits of physical exercise may be affected by air quality. A 2025 cross-national study involving 1.5 million adults demonstrated that high levels of ambient PM2.5 can significantly diminish the protective effects of leisure-time physical activity against all-cause and cause-specific mortality. Below an annual average concentration of '''25 μg/m3''', regular exercise reduces all-cause mortality by approximately 30%. This benefit is halved (to 12–15%) when concentrations exceeded 25 μg/m3. In addition, the protective effects of exercise against cancer-related mortality become statistically non-significant when PM2.5 levels reach '''35 μg/m3''' or higher.<ref name="Ku2025">{{cite journal |last1=Ku |first1=PW |last2=Steptoe |first2=A |last3=Hamer |first3=M |last4=Zaninotto |first4=P |last5=Stamatakis |first5=E |last6=Lin |first6=CH |last7=Yu |first7=B |last8=Hvidtfeldt |first8=UA |last9=Lao |first9=XQ |last10=Lin |first10=HH |last11=Lo |first11=WC |last12=Raaschou-Nielsen |first12=O |last13=Sun |first13=S |last14=Tian |first14=L |last15=Wang |first15=SF |last16=Zeng |first16=Y |last17=Zhang |first17=Y |last18=Chen |first18=ST |last19=Huang |first19=CF |last20=Xia |first20=Y |last21=Chen |first21=LJ |title=Does ambient PM(2.5) reduce the protective association of leisure-time physical activity with mortality? A systematic review, meta-analysis, and individual-level pooled analysis of cohort studies involving 1.5 million adults. |journal=BMC Medicine |date=28 November 2025 |volume=23 |issue=1 |page=647 |doi=10.1186/s12916-025-04496-y |doi-access=free|pmid=41310726 |pmc=12661664 }}</ref>

==== Respiratory system ==== {{See also|Chronic cough}} thumb |Though the rate of exposure to ground-level ozone ("smog") and small-particulate matter ("soot") has been declining, in 2026, nearly half of people in the US under age{{nbsp}}18 live in an area receiving a failing grade for at least one measure of air pollution.<ref name=WashPost_20260422>American Lung Association ''State of the Air 2026'' as presented by {{cite news |last1=Dennis |first1=Brady |last2=Noll |first2=Ben |title=More Americans are exposed to polluted air in the United States. See where. |url=https://www.washingtonpost.com/climate-environment/2026/04/22/unhealthy-air-pollution-report/ |newspaper=The Washington Post |date=22 April 2026}}</ref> Particulate matter is associated with respiratory diseases including asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, pneumonia, acute respiratory distress syndrome, and lung cancer. PM10 rarely travels beyond the upper airway, while finer particulates such as PM2.5 and PM0.1 can go deeper into the lungs and cause greater harms to respiratory health.<ref name="Hamanaka"/><ref name="Ma"/>

The Multi-City Multi-Country (MCC) study examined daily data on mortality and air pollution from 652 cities in 24 areas, including North America, Europe, and Eastern Asia. PM2.5 concentrations were associated with higher overall and respiratory mortality.<ref name="Hamanaka"/><ref name="Liu2019">{{cite journal |last1=Liu |first1=C |last2=Chen |first2=R |last3=Sera |first3=F |last4=Vicedo-Cabrera |first4=AM |last5=Guo |first5=Y |last6=Tong |first6=S |last7=Coelho |first7=MSZS |last8=Saldiva |first8=PHN |last9=Lavigne |first9=E |last10=Matus |first10=P |last11=Valdes Ortega |first11=N |last12=Osorio Garcia |first12=S |last13=Pascal |first13=M |last14=Stafoggia |first14=M |last15=Scortichini |first15=M |last16=Hashizume |first16=M |last17=Honda |first17=Y |last18=Hurtado-Díaz |first18=M |last19=Cruz |first19=J |last20=Nunes |first20=B |last21=Teixeira |first21=JP |last22=Kim |first22=H |last23=Tobias |first23=A |last24=Íñiguez |first24=C |last25=Forsberg |first25=B |last26=Åström |first26=C |last27=Ragettli |first27=MS |last28=Guo |first28=YL |last29=Chen |first29=BY |last30=Bell |first30=ML |last31=Wright |first31=CY |last32=Scovronick |first32=N |last33=Garland |first33=RM |last34=Milojevic |first34=A |last35=Kyselý |first35=J |last36=Urban |first36=A |last37=Orru |first37=H |last38=Indermitte |first38=E |last39=Jaakkola |first39=JJK |last40=Ryti |first40=NRI |last41=Katsouyanni |first41=K |last42=Analitis |first42=A |last43=Zanobetti |first43=A |last44=Schwartz |first44=J |last45=Chen |first45=J |last46=Wu |first46=T |last47=Cohen |first47=A |last48=Gasparrini |first48=A |last49=Kan |first49=H |title=Ambient Particulate Air Pollution and Daily Mortality in 652 Cities. |journal=The New England Journal of Medicine |date=22 August 2019 |volume=381 |issue=8 |pages=705–715 |doi=10.1056/NEJMoa1817364 |pmid=31433918 |pmc=7891185 }}</ref> Similar results are reported by other studies.<ref name="Hamanaka"/><ref name="Liu2022">{{cite journal |last1=Liu |first1=C |last2=Cai |first2=J |last3=Chen |first3=R |last4=Sera |first4=F |last5=Guo |first5=Y |last6=Tong |first6=S |last7=Li |first7=S |last8=Lavigne |first8=E |last9=Correa |first9=PM |last10=Ortega |first10=NV |last11=Orru |first11=H |last12=Maasikmets |first12=M |last13=Jaakkola |first13=JJK |last14=Ryti |first14=N |last15=Breitner |first15=S |last16=Schneider |first16=A |last17=Katsouyanni |first17=K |last18=Samoli |first18=E |last19=Hashizume |first19=M |last20=Honda |first20=Y |last21=Ng |first21=CFS |last22=Diaz |first22=MH |last23=la Cruz Valencia |first23=C |last24=Rao |first24=S |last25=Palomares |first25=AD |last26=Pereira da Silva |first26=S |last27=Madureira |first27=J |last28=Holobâc |first28=IH |last29=Fratianni |first29=S |last30=Scovronick |first30=N |last31=Garland |first31=RM |last32=Tobias |first32=A |last33=Íñiguez |first33=C |last34=Forsberg |first34=B |last35=Åström |first35=C |last36=Vicedo-Cabrera |first36=AM |last37=Ragettli |first37=MS |last38=Guo |first38=YL |last39=Pan |first39=SC |last40=Milojevic |first40=A |last41=Bell |first41=ML |last42=Zanobetti |first42=A |last43=Schwartz |first43=J |last44=Gasparrini |first44=A |last45=Kan |first45=H |title=Coarse Particulate Air Pollution and Daily Mortality: A Global Study in 205 Cities. |journal=American Journal of Respiratory and Critical Care Medicine |date=15 October 2022 |volume=206 |issue=8 |pages=999–1007 |doi=10.1164/rccm.202111-2657OC |pmid=35671471 |hdl=10261/282448 }}</ref>

The IARC and WHO designate particulates as a Group 1 carcinogen.<ref name="Arif"/> A 2024 meta-analysis of 66 cancer studies globally reported that for every increase of 10 μg/m{{sup|3}} in PM{{sub|2.5}}, the lung cancer rate rose 8.5%.<ref name="Arif"/> Air pollution is also associated with higher incidence and prevalence, worsening of symptoms, and more exacerbations in asthma, COPD and other conditions.<ref name="Espejo">{{cite journal |last1=Espejo |first1=D |last2=Plaza |first2=V |last3=Quirce |first3=S |last4=Trigueros |first4=JA |last5=Muñoz |first5=X |title=Influence of Outdoor Air Pollutants on Asthma: A Narrative Review. |journal=Open Respiratory Archives |date=July 2025 |volume=7 |issue=3 |article-number=100448 |doi=10.1016/j.opresp.2025.100448 |doi-access=free |pmid=40677935 |pmc=12269595 }}</ref><ref name="Chou2023">{{cite journal |last1=Chou |first1=CH |last2=Chen |first2=YF |last3=Peng |first3=HC |last4=Chen |first4=CY |last5=Cheng |first5=BW |title=Environmental pollutants increase the risks of acute exacerbation in patients with chronic airway disease. |journal=Frontiers in Public Health |date=2023 |volume=11 |article-number=1215224 |doi=10.3389/fpubh.2023.1215224 |doi-access=free |pmid=38026400 |pmc=10643209 |bibcode=2023FrPH...1115224C }}</ref>

Short-term exposure is also associated with increased emergency room visits and hospitalizations relating to asthma, COPD, upper respiratory infections (URI), and pneumonia.<ref name="Krall">{{cite journal |last1=Krall |first1=JR |last2=Chang |first2=HH |last3=Waller |first3=LA |last4=Mulholland |first4=JA |last5=Winquist |first5=A |last6=Talbott |first6=EO |last7=Rager |first7=JR |last8=Tolbert |first8=PE |last9=Sarnat |first9=SE |title=A multicity study of air pollution and cardiorespiratory emergency department visits: Comparing approaches for combining estimates across cities. |journal=Environment International |date=November 2018 |volume=120 |pages=312–320 |doi=10.1016/j.envint.2018.07.033 |pmid=30107292 |pmc=6218942 |bibcode=2018EnInt.120..312K }}</ref><ref name="Chou2023"/> For example, a 10 μg/m3 increase in daily PM2.5 was associated with a 1.5% increase in asthma-related emergency room visits by adults and a 3.6% increase in pediatric emergency room visits.<ref name="Madaniyazi">{{cite journal |last1=Madaniyazi |first1=L |last2=Xerxes |first2=S |title=Outdoor air pollution and the onset and exacerbation of asthma. |journal=Chronic Diseases and Translational Medicine |date=June 2021 |volume=7 |issue=2 |pages=100–106 |doi=10.1016/j.cdtm.2021.04.003 |pmid=34136769 |pmc=8180519 }}</ref><ref name="Fan2016">{{cite journal |last1=Fan |first1=J |last2=Li |first2=S |last3=Fan |first3=C |last4=Bai |first4=Z |last5=Yang |first5=K |title=The impact of PM2.5 on asthma emergency department visits: a systematic review and meta-analysis. |journal=Environmental Science and Pollution Research International |date=January 2016 |volume=23 |issue=1 |pages=843–50 |doi=10.1007/s11356-015-5321-x |pmid=26347419 |bibcode=2016ESPR...23..843F }}</ref>

Airborne particulate matter can carry microbes into the respiratory system and increase the risk of respiratory infections and allergic reactions.<ref name="Arca">{{cite journal |last1=Arca-Lafuente |first1=S |last2=Nuñez-Corcuera |first2=B |last3=Ramis |first3=R |last4=Karakitsios |first4=S |last5=Sarigiannis |first5=D |last6=García Dos Santos |first6=S |last7=Fernández-Rodríguez |first7=A |last8=Briz |first8=V |title=Effects of urban airborne particulate matter exposure on the human upper respiratory tract microbiome: a systematic review. |journal=Respiratory Research |date=28 March 2025 |volume=26 |issue=1 |page=118 |doi=10.1186/s12931-025-03179-9 |doi-access=free |pmid=40156019 |pmc=11954284 }}</ref> PM2.5 suppresses immune responses and worsens inflammation, increasing severity and mortality of bacterial and viral infections in the respiratory system.<ref name="Ma"/> PM2.5 worsens bacterial infections like ''Staphylococcus aureus'', ''Streptococcus pneumoniae'', ''Mycobacterium tuberculosis,'' ''Pseudomonas aeruginosa'' and ''Mycoplasma pneumoniae''.<ref name="Ma"/> Particulate matter also interferes with immune responses that fight viral infections like COVID-19.<ref name="Ma"/><ref>{{Cite journal|title = Relation between PM{{sub|2.5}} pollution and Covid-19 mortality in Western Europe for the 2020–2022 period| year=2022 | pmc=9310379 | last1=Renard | first1=J. B. | last2=Surcin | first2=J. | last3=Annesi-Maesano | first3=I. | last4=Delaunay | first4=G. | last5=Poincelet | first5=E. | last6=Dixsaut | first6=G. | journal=The Science of the Total Environment | volume=848 | article-number=157579 | doi=10.1016/j.scitotenv.2022.157579 | pmid=35901896 |bibcode=2022ScTEn.84857579R }}</ref><ref>{{Cite journal|title = Assessing the impact of long-term exposure to nine outdoor air pollutants on COVID-19 spatial spread and related mortality in 107 Italian provinces| year=2022 | doi=10.1038/s41598-022-17215-x | last1=Perone | first1=Gaetano | journal=Scientific Reports | volume=12 | issue=1 | article-number=13317 | pmid=35922645 | pmc=9349267 | bibcode=2022NatSR..1213317P }}</ref><ref>{{cite journal |doi=10.1038/s41370-021-00366-w|doi-access=free|title=SARS-CoV-2 test positivity rate in Reno, Nevada: Association with PM{{sub|2.5}} during the 2020 wildfire smoke events in the western United States |year=2021 |last1=Kiser |first1=Daniel |last2=Elhanan |first2=Gai |last3=Metcalf |first3=William J. |last4=Schnieder |first4=Brendan |last5=Grzymski |first5=Joseph J. |journal=Journal of Exposure Science & Environmental Epidemiology |volume=31 |issue=5 |pages=797–803 |pmid=34257389 |pmc=8276229 |bibcode=2021JESEE..31..797K }}</ref><ref>{{cite journal |doi=10.1038/s41598-021-85751-z |doi-access=free|title=A global association between Covid-19 cases and airborne particulate matter at regional level |year=2021 |last1=Solimini |first1=Angelo |last2=Filipponi |first2=F. |last3=Fegatelli |first3=D. Alunni |last4=Caputo |first4=B. |last5=De Marco |first5=C. M. |last6=Spagnoli |first6=A. |last7=Vestri |first7=A. R. |journal=Scientific Reports |volume=11 |issue=1 |page=6256 |pmid=33737616 |pmc=7973572 |bibcode=2021NatSR..11.6256S }}</ref> PM2.5 has been found to promote allergic reactions and cytokine storms during respiratory viral infections.<ref name="Ma"/>

==== Cardiovascular system ==== Particulate matter is associated with increases in blood pressure, blood clotting, and insulin resistance; damage to the endothelial cells that line blood vessels, causing vascular injury or dysfunction; accelerated buildup of fatty plaques in arteries,<ref name="Liang">{{cite journal |last1=Liang |first1=S |last2=Zhang |first2=J |last3=Ning |first3=R |last4=Du |first4=Z |last5=Liu |first5=J |last6=Batibawa |first6=JW |last7=Duan |first7=J |last8=Sun |first8=Z |title=The critical role of endothelial function in fine particulate matter-induced atherosclerosis. |journal=Particle and Fibre Toxicology |date=4 December 2020 |volume=17 |issue=1 |page=61 |doi=10.1186/s12989-020-00391-x |doi-access=free |pmid=33276797 |pmc=7716453 |bibcode=2020PFTox..17...61L }}</ref><ref name="Bhatnagar" /><ref name="Yu" /> and reduced elasticity of arteries.<ref name="Liang"/><ref name="Crooke">{{cite web |last1=Crooke |first1=Ranulf |title=The Invisible Risk: How Air Pollution is Quietly Driving High Blood Pressure — WellFounded - Founders Health & Concierge Performance Medicine {{!}} CHHP Longevity Research |url=https://wellfounded.health/insights/the-invisible-risk-how-air-pollution-is-quietly-driving-high-blood-pressure |website=WellFounded - Founders Health & Concierge Performance Medicine {{!}} CHHP Longevity Research |access-date=13 April 2026}}</ref>

PM2.5 has been shown to increase both oxidative stress and inflammation. Oxidative stress decreases availability of nitric oxide, needed to maintain the elasticity of blood vessels. Chronic inflammation damages blood vessel walls, interfering with their ability to relax and regulate pressure.<ref name="Liang"/>

PM2.5 is associated with increased cardiovascular illness and mortality<ref name="Guo">{{cite journal |last1=Guo |first1=J |last2=Chai |first2=G |last3=Song |first3=X |last4=Hui |first4=X |last5=Li |first5=Z |last6=Feng |first6=X |last7=Yang |first7=K |title=Long-term exposure to particulate matter on cardiovascular and respiratory diseases in low- and middle-income countries: A systematic review and meta-analysis. |journal=Frontiers in Public Health |date=2023 |volume=11 |article-number=1134341 |doi=10.3389/fpubh.2023.1134341 |doi-access=free |pmid=37056647 |pmc=10089304 |bibcode=2023FrPH...1134341G }}</ref><ref name="Hamanaka" /><ref name="Liu2019" /> from diseases such as ischemic heart disease, cerebrovascular disease (stroke), heart failure, arrhythmia, heart attack, atherosclerosis, and hypertension.<ref name="Zhao">{{cite journal |last1=Zhao |first1=M |last2=Xu |first2=Z |last3=Guo |first3=Q |last4=Gan |first4=Y |last5=Wang |first5=Q |last6=Liu |first6=JA |title=Association between long-term exposure to PM(2.5) and hypertension: A systematic review and meta-analysis of observational studies. |journal=Environmental Research |date=March 2022 |volume=204 |issue=Pt D |article-number=112352 |doi=10.1016/j.envres.2021.112352 |pmid=34762927}}</ref><ref name="Krittanawong" /><ref name="Bhatnagar" /><ref name="Liu2019" /> PM2.5 is also associated with increased cardiovascular-related hospital admissions.<ref name="Wei">{{cite journal |last1=Wei |first1=Y |last2=Feng |first2=Y |last3=Danesh Yazdi |first3=M |last4=Yin |first4=K |last5=Castro |first5=E |last6=Shtein |first6=A |last7=Qiu |first7=X |last8=Peralta |first8=AA |last9=Coull |first9=BA |last10=Dominici |first10=F |last11=Schwartz |first11=JD |title=Exposure-response associations between chronic exposure to fine particulate matter and risks of hospital admission for major cardiovascular diseases: population based cohort study |journal=BMJ |date=21 February 2024 |volume=384 |article-number=e076939 |doi=10.1136/bmj-2023-076939 |pmid=38383041 |pmc=10879983 |language=en |issn=1756-1833}}</ref>

In 2022, a systematic review and analysis of 27 studies with approximately 42 million participants reported that each 10 μg/m3 increase in long-term PM2.5 exposure was associated with a 21% higher risk of developing hypertension over time.<ref name="Zhao"/> A 2020 analysis of cause-specific cardiovascular disease mortality reported that each increase of 10 μg/m3 in PM2.5 was associated with a 16% increase in mortality from ischaemic heart disease and a 14% increase in mortality from stroke.<ref name="Hayes">{{cite journal |last1=Hayes |first1=RB |last2=Lim |first2=C |last3=Zhang |first3=Y |last4=Cromar |first4=K |last5=Shao |first5=Y |last6=Reynolds |first6=HR |last7=Silverman |first7=DT |last8=Jones |first8=RR |last9=Park |first9=Y |last10=Jerrett |first10=M |last11=Ahn |first11=J |last12=Thurston |first12=GD |title=PM2.5 air pollution and cause-specific cardiovascular disease mortality. |journal=International Journal of Epidemiology |date=1 February 2020 |volume=49 |issue=1 |pages=25–35 |doi=10.1093/ije/dyz114 |pmid=31289812 |pmc=7124502 }}</ref>

==== Nervous system ==== {{See also|Lead poisoning|Manganism|Substance-induced psychosis}} {{Further|Neuroplastic effects of pollution}}

The effects of air pollution and particulate matter on cognitive performance are an active area of research.<ref name="Thompson">{{cite journal |last1=Thompson |first1=R |last2=Smith |first2=RB |last3=Karim |first3=YB |last4=Shen |first4=C |last5=Drummond |first5=K |last6=Teng |first6=C |last7=Toledano |first7=MB |title=Air pollution and human cognition: A systematic review and meta-analysis. |journal=The Science of the Total Environment |date=10 February 2023 |volume=859 |issue=Pt 2 |article-number=160234 |doi=10.1016/j.scitotenv.2022.160234 |pmid=36427724 |bibcode=2023ScTEn.85960234T |hdl=10044/1/101759 }}</ref> Meta-analysis and reviews indicate that exposure to PM{{sub|2.5}}, PM{{sub|10}}, and SO{{sub|2}} are associated with decreases in global cognitive function and with cognitive decline.<ref name="Meo">{{cite journal |last1=Meo |first1=SA |last2=Shaikh |first2=N |last3=Alotaibi |first3=M |last4=AlWabel |first4=AA |last5=Alqumaidi |first5=H |title=Effect of air pollutants particulate matter (PM(2.5), PM(10)), sulfur dioxide (SO(2)) and ozone (O(3)) on cognitive health. |journal=Scientific Reports |date=23 August 2024 |volume=14 |issue=1 |page=19616 |doi=10.1038/s41598-024-70646-6 |pmid=39179784 |pmc=11343771 }}</ref><ref name="Gong"/> Epidemiological studies also suggest a link between PM{{sub|2.5}} exposure and cognitive decline.<ref>{{Cite journal |last1=You |first1=Ran |last2=Ho |first2=Yuen-Shan |last3=Chang |first3=Raymond Chuen-Chung |date=2022-02-22 |title=The pathogenic effects of particulate matter on neurodegeneration: a review |journal=Journal of Biomedical Science |volume=29 |issue=1 |page=15 |doi=10.1186/s12929-022-00799-x |doi-access=free |issn=1423-0127 |pmc=8862284 |pmid=35189880}}</ref> PM2.5 is associated with reduced cognitive function in children, as measured by IQ scores.<ref>{{cite journal |last1=Alter |first1=NC |last2=Whitman |first2=EM |last3=Bellinger |first3=DC |last4=Landrigan |first4=PJ |title=Quantifying the association between PM(2.5) air pollution and IQ loss in children: a systematic review and meta-analysis. |journal=Environmental Health : A Global Access Science Source |date=18 November 2024 |volume=23 |issue=1 |page=101 |doi=10.1186/s12940-024-01122-x |doi-access=free |pmid=39551729 |pmc=11572473 }}</ref> Improved air quality has been found to have a protective effect on cognitive function.<ref name="Meo"/>

Long-term PM{{sub|2.5}} exposure is associate with increased risk for all-cause dementia, Alzheimer's disease and Parkinson's disease. PM{{sub|10}} is also associated with increased risk of vascular dementia. <ref name="Gong">{{cite journal |last1=Gong |first1=Y |last2=Zhang |first2=X |last3=Zhao |first3=X |last4=Chang |first4=H |last5=Zhang |first5=J |last6=Gao |first6=Z |last7=Mi |first7=Y |last8=Chen |first8=Y |last9=Zhang |first9=H |last10=Huang |first10=C |last11=Yu |first11=Z |title=Global ambient particulate matter pollution and neurodegenerative disorders: a systematic review of literature and meta-analysis. |journal=Environmental Science and Pollution Research International |date=March 2023 |volume=30 |issue=14 |pages=39418–39430 |doi=10.1007/s11356-023-25731-0 |pmid=36763275 |bibcode=2023ESPR...3039418G }}</ref><ref name="Jones">{{cite journal |last1=Jones |first1=A |last2=Ali |first2=MU |last3=Mayhew |first3=A |last4=Aryal |first4=K |last5=Correia |first5=RH |last6=Dash |first6=D |last7=Manis |first7=DR |last8=Rehman |first8=A |last9=O'Connell |first9=ME |last10=Taler |first10=V |last11=Costa |first11=AP |last12=Hogan |first12=DB |last13=Wolfson |first13=C |last14=Raina |first14=P |last15=Griffith |first15=L |title=Environmental risk factors for all-cause dementia, Alzheimer's disease dementia, vascular dementia, and mild cognitive impairment: An umbrella review and meta-analysis. |journal=Environmental Research |date=1 April 2025 |volume=270 |article-number=121007 |doi=10.1016/j.envres.2025.121007 |pmid=39889875 |bibcode=2025ER....27021007J }}</ref> Risk of Alzheimer's disease is associated with PM{{sub|2.5}}, and is higher in heavily polluted regions than in lightly polluted regions.<ref name="Fu">{{cite journal |last1=Fu |first1=P |last2=Yung |first2=KKL |title=Air Pollution and Alzheimer's Disease: A Systematic Review and Meta-Analysis. |journal=Journal of Alzheimer's Disease : JAD |date=2020 |volume=77 |issue=2 |pages=701–714 |doi=10.3233/JAD-200483 |pmid=32741830}}</ref><ref>{{cite journal |last1=O'Piela |first1=DR |last2=Durisek GR |first2=3rd |last3=Escobar |first3=YH |last4=Mackos |first4=AR |last5=Wold |first5=LE |title=Particulate matter and Alzheimer's disease: an intimate connection. |journal=Trends in Molecular Medicine |date=September 2022 |volume=28 |issue=9 |pages=770–780 |doi=10.1016/j.molmed.2022.06.004 |pmid=35840480 |pmc=9420776 }}</ref> There is also a strong association between Parkinson's disease and PM{{sub|2.5}}. Higher rates of Parkinson's disease are generally associated with higher levels of PM{{sub|2.5}}.<ref>{{cite journal |last1=Xie |first1=C |last2=Xia |first2=X |last3=Wang |first3=K |last4=Yan |first4=J |last5=Bai |first5=L |last6=Guo |first6=L |last7=Li |first7=X |last8=Wu |first8=S |title=Ambient Air Pollution and Parkinson's Disease and Alzheimer's Disease: An Updated Meta-Analysis. |journal=Toxics |date=15 February 2025 |volume=13 |issue=2 |page=139 |doi=10.3390/toxics13020139 |doi-access=free |pmid=39997954 |pmc=11861764 |bibcode=2025Toxic..13..139X }}</ref>

Air pollution may increase the risk of mental disorders such as depression, anxiety,<ref name="Zundel"/> schizophrenia<ref>{{cite journal |last1=Song |first1=R |last2=Liu |first2=L |last3=Wei |first3=N |last4=Li |first4=X |last5=Liu |first5=J |last6=Yuan |first6=J |last7=Yan |first7=S |last8=Sun |first8=X |last9=Mei |first9=L |last10=Liang |first10=Y |last11=Li |first11=Y |last12=Jin |first12=X |last13=Wu |first13=Y |last14=Pan |first14=R |last15=Yi |first15=W |last16=Song |first16=J |last17=He |first17=Y |last18=Tang |first18=C |last19=Liu |first19=X |last20=Cheng |first20=J |last21=Su |first21=H |title=Short-term exposure to air pollution is an emerging but neglected risk factor for schizophrenia: A systematic review and meta-analysis. |journal=The Science of the Total Environment |date=1 January 2023 |volume=854 |article-number=158823 |doi=10.1016/j.scitotenv.2022.158823 |pmid=36116638 |bibcode=2023ScTEn.85458823S }}</ref>, bipolar disorder and psychosis<ref name="Braithwaite" />, and of suicide.<ref name="economic" /><ref name="Liu2021" /><ref>{{cite journal |last1=Go |first1=TH |last2=Kim |first2=MH |last3=Choi |first3=YY |last4=Han |first4=J |last5=Kim |first5=C |last6=Kang |first6=DR |title=The short-term effect of ambient particulate matter on suicide death. |journal=Environmental Health : A Global Access Science Source |date=3 January 2024 |volume=23 |issue=1 |page=3 |doi=10.1186/s12940-023-01042-2 |doi-access=free |pmid=38169380 |pmc=10763266 |bibcode=2024EnvHe..23....3G }}</ref><ref name="Symons">{{Cite web |last=Symons |first=Angela |date=15 December 2022 |title=Suicide rates rise as air quality worsens, study finds |url=https://www.euronews.com/green/2022/12/15/suicide-may-be-more-common-in-areas-worst-hit-by-air-pollution-new-study-reveals |access-date=19 December 2022 |website=euronews |language=en}}</ref> Increases in symptoms and behaviors may be related to underlying changes in neurotransmitters and neuromodulators.<ref name="Zundel">{{cite journal |last1=Zundel |first1=CG |last2=Ryan |first2=P |last3=Brokamp |first3=C |last4=Heeter |first4=A |last5=Huang |first5=Y |last6=Strawn |first6=JR |last7=Marusak |first7=HA |title=Air pollution, depressive and anxiety disorders, and brain effects: A systematic review. |journal=Neurotoxicology |date=December 2022 |volume=93 |pages=272–300 |doi=10.1016/j.neuro.2022.10.011 |pmid=36280190 |pmc=10015654 |bibcode=2022NeuTx..93..272Z }}</ref> Relationships between depression, suicide, and air pollution are complicated. For example, daily increases in both temperature and air pollution have been found to increase the risk of death from suicide, with stronger effects for women than men.<ref name="Villeneuve">{{cite journal |last1=Villeneuve |first1=PJ |last2=Huynh |first2=D |last3=Lavigne |first3=É |last4=Colman |first4=I |last5=Anisman |first5=H |last6=Peters |first6=C |last7=Rodríguez-Villamizar |first7=LA |title=Daily changes in ambient air pollution concentrations and temperature and suicide mortality in Canada: Findings from a national time-stratified case-crossover study. |journal=Environmental Research |date=15 April 2023 |volume=223 |article-number=115477 |doi=10.1016/j.envres.2023.115477 |pmid=36781013 |bibcode=2023ER....22315477V }}</ref> Air pollution is also associated with increased levels of violence and crime.<ref name="economic" /><ref name="Berman" />

Air pollution may increase the risk of neurodevelopmental disorders such as autism.<ref>{{cite journal |last1=Dou |first1=J |last2=Zhang |first2=K |last3=Xie |first3=R |last4=Xu |first4=H |last5=Pan |first5=Q |last6=Xiao |first6=X |last7=Luo |first7=Y |last8=Xu |first8=S |last9=Xiao |first9=W |last10=Wu |first10=D |last11=Wang |first11=B |last12=Zhang |first12=L |last13=Sun |first13=C |last14=Liu |first14=Y |title=Investigating the Effects of Long-Term Fine Particulate Matter Exposure on Autism Spectrum Disorder Severity: Evidence from Multiple Analytical Approaches. |journal=Toxics |date=28 October 2025 |volume=13 |issue=11 |page=922 |doi=10.3390/toxics13110922 |doi-access=free |pmid=41304474 |pmc=12656233 |bibcode=2025Toxic..13..922D }}</ref> A review and meta-analysis including 20 studies reports an increased risk of autism spectrum disorders (ASD) in children following exposures to PM{{sub|2.5}} prenatally and for the first year and second years after birth.<ref name="Lin2022">{{cite journal |last1=Lin |first1=LZ |last2=Zhan |first2=XL |last3=Jin |first3=CY |last4=Liang |first4=JH |last5=Jing |first5=J |last6=Dong |first6=GH |title=The epidemiological evidence linking exposure to ambient particulate matter with neurodevelopmental disorders: A systematic review and meta-analysis. |journal=Environmental Research |date=June 2022 |volume=209 |article-number=112876 |doi=10.1016/j.envres.2022.112876 |pmid=35134379 |bibcode=2022ER....20912876L }}</ref> ASD and Attention Deficit Hyperactivity Disorder (ADHD) have been linked to early-life exposures to both PM{{sub|2.5}} and NO{{sub|2}}.<ref>{{cite journal |last1=Mazahir |first1=FA |last2=Shukla |first2=A |last3=Albastaki |first3=NA |title=The association of particulate matter PM(2.5) and nitrogen oxides from ambient air pollution and mental health of children and young adults- a systematic review. |journal=Reviews on Environmental Health |date=25 September 2025 |volume=40 |issue=3 |pages=495–536 |doi=10.1515/reveh-2024-0120 |pmid=40074563 |bibcode=2025RvEH...40..495M }}</ref>

While mechanisms connecting PM{{sub|2.5}} exposure and cognitive decline are not fully understood, research suggests that particulate matter may reach the brain via multiple pathways, including inhalation, ingestion, and the olfactory system.<ref name="Meo"/><ref>{{cite journal |last1=Kanninen |first1=K.M. |last2=Lampinen |first2=R. |last3=Rantanen |first3=L.M. |last4=Odendaal |first4=L. |last5=Jalava |first5=P. |last6=Chew |first6=S. |last7=White |first7=A.R. |title=Olfactory cell cultures to investigate health effects of air pollution exposure: Implications for neurodegeneration |journal=Neurochemistry International |date=June 2020 |volume=136 |article-number=104729 |doi=10.1016/j.neuint.2020.104729 |pmid=32201281 }}</ref><ref>{{cite journal |last1=Liu |first1=XQ |last2=Huang |first2=J |last3=Song |first3=C |last4=Zhang |first4=TL |last5=Liu |first5=YP |last6=Yu |first6=L |title=Neurodevelopmental toxicity induced by PM2.5 Exposure and its possible role in Neurodegenerative and mental disorders. |journal=Human & Experimental Toxicology |date=January 2023 |volume=42 |page=9603271231191436 |article-number=09603271231191436 |doi=10.1177/09603271231191436 |pmid=37537902 |bibcode=2023HETox..4291436L }}</ref> Respiratory inflammation can lead to systematic inflammation, interfering with the blood–brain barrier and enabling toxins and other materials to enter the brain. There, particulate matter causes damage as a result of neuroinflammation, oxidative stress, buildup of misfolded proteins, and neuronal cell death.<ref name="Meo"/>

==== Gastrointestinal and metabolic systems ==== In the gastrointestinal system, particulate matter is linked to inflammatory bowel disease, colorectal cancer, appendicitis, and kidney and liver diseases.<ref name="Arca" /><ref name="Yu" /> PM2.5 can enter the gastrointestinal tract by being ingested in food or water. It can also be inhaled into the respiratory tract and cleared from the lungs in mucus, which is then swallowed and reaches the gastrointestinal tract. PM2.5 that has entered the bloodstream via the lungs can travel to the gut through systemic circulation. PM2.5 increases systemic inflammation and oxidative stress. These mechanisms disrupt the intestinal barrier, increasing intestinal permeability and enabling harmful substances to enter the circulatory system and affect the immune system. PM2.5 exposure alters the composition of gut microbiota, increasing the presence of ''Lactobacillus'', ''Parabacteroides'', ''Firmicutes'' and ''Akkermansia'', and decreasing ''Bacteroidetes'' and ''Prevotella''. Changes in microbiota and metabolites impair function and gut health. High-risk constituents such as toxic heavy metals and organic compounds cause further harms.<ref name="Yu">{{cite journal |last1=Yu |first1=X |last2=Qiu |first2=Z |last3=Zeng |first3=X |last4=Zhang |first4=S |last5=Tang |first5=J |last6=Wu |first6=Y |last7=Zhang |first7=L |last8=Huo |first8=X |last9=Liu |first9=C |last10=Liu |first10=D |title=Influences of PM(2.5) on gut physiology, microbiota and metabolites. |journal=Ecotoxicology and Environmental Safety |date=15 November 2025 |volume=307 |article-number=119423 |doi=10.1016/j.ecoenv.2025.119423 |pmid=41241996}}</ref><ref name="Arca" />

Particulate matter is also linked to diabetes.<ref name="Liviero" /> Exposure to PM10 and PM2.5 has been shown to increase the risk of type 2 diabetes. As of 2025, little research was available on effects in type 1 diabetes mellitus and gestational diabetes mellitus.<ref name="Jiang" /> Microbiota imbalance and decreases in gut microbiota diversity may worsen insulin resistance and affect type 2 diabetes.<ref name="Yu" />

There is some evidence to suggest that particulate matter is a risk factor for Metabolic syndrome (MetS). MetS involves multiple metabolic-related disorders: central obesity, high blood pressure, high fasting glucose, and low high-density lipoprotein cholesterol (low-HDL). PM2.5 and chemical components such as sulfates and black carbon may affect MetS-related disorders.<ref name="Kim2025" /><ref>{{cite journal |last1=Guo |first1=Q |last2=Zhao |first2=Y |last3=Xue |first3=T |last4=Zhang |first4=J |last5=Duan |first5=X |title=Association of PM(2.5) and Its Chemical Compositions with Metabolic Syndrome: A Nationwide Study in Middle-Aged and Older Chinese Adults. |journal=International Journal of Environmental Research and Public Health |date=8 November 2022 |volume=19 |issue=22 |article-number=14671 |doi=10.3390/ijerph192214671 |doi-access=free |pmid=36429390 |pmc=9690751 }}</ref>

==== Reproductive system ==== Particulate matter and PM{{sub|2.5}} exposure have been studied with respect to the reproductive system.<ref name=":12" /><ref name=":13" /><ref name="Basilio"/> Reduced sperm counts, irregular menstruation,<ref name="Coppeta">{{cite journal |last1=Coppeta |first1=L |last2=Ferrari |first2=C |last3=Ippoliti |first3=L |last4=Campagnolo |first4=L |last5=Magrini |first5=A |title=Systematic literature review and meta-analysis on the reproductive effects of micro- pollutants in humans and animals. |journal=Frontiers in Toxicology |date=2025 |volume=7 |article-number=1671098 |doi=10.3389/ftox.2025.1671098 |doi-access=free |pmid=41347044 |pmc=12673271 }}</ref> and higher rates of infertility in both men and women have been correlated with exposure to particulates.<ref name="Wang2021">{{cite journal |last1=Wang |first1=L |last2=Luo |first2=D |last3=Liu |first3=X |last4=Zhu |first4=J |last5=Wang |first5=F |last6=Li |first6=B |last7=Li |first7=L |title=Effects of PM(2.5) exposure on reproductive system and its mechanisms. |journal=Chemosphere |date=February 2021 |volume=264 |issue=Pt 1 |article-number=128436 |doi=10.1016/j.chemosphere.2020.128436 |pmid=33032215 |bibcode=2021Chmsp.26428436W }}</ref><ref>{{cite news |last1=Carrington |first1=Damian |title=Air pollution significantly raises risk of infertility, study finds |url=https://www.theguardian.com/environment/2021/feb/17/air-pollution-significantly-raises-risk-of-infertility-study-finds |work=The Guardian |date=17 February 2021 }}</ref> PM{{sub|2.5}} has been shown to disrupt hormone levels and decrease the supply of eggs in a woman's ovaries. PM{{sub|2.5}} accumulates in the reproductive organs and can cause male infertility.<ref name="Wang2021" />

Pregnant women exposed to PM{{sub|2.5}} are at higher risk for developing gestational diabetes and hypertensive diseases of pregnancy such as gestational hypertension and pre-eclampsia.<ref name=":16" /> Exposure to particulate matter is also associated with increased risk of spontaneous abortion,<ref name="Wang2021" /> premature delivery,<ref name=":15" /> low birth weight, and birth defects.<ref name=":16" /> Maternal PM{{sub|2.5}} exposure during pregnancy is associated with high blood pressure in children.<ref>{{cite journal | vauthors = Zhang M, Mueller NT, Wang H, Hong X, Appel LJ, Wang X | title = Maternal Exposure to Ambient Particulate Matter ≤2.5 μm During Pregnancy and the Risk for High Blood Pressure in Childhood | journal = Hypertension | volume = 72 | issue = 1 | pages = 194–201 | date = July 2018 | pmid = 29760154 | pmc = 6002908 | doi = 10.1161/HYPERTENSIONAHA.117.10944 }}</ref>

Overall epidemiologic and toxicological evidence suggests causal relationships between long-term exposure to fine and ultrafine particulate matter and adverse outcomes in offspring.<ref name="Johnson" /> Particulate matter exposure can cause inflammation, oxidative stress, endocrine disruption, and impaired transport across the placenta, all of which can lower birth weight.<ref name="Johnson" /><ref name="Parasin">{{cite journal |last1=Parasin |first1=N |last2=Amnuaylojaroen |first2=T |last3=Saokaew |first3=S |title=Prenatal PM(2.5) Exposure and Its Association with Low Birth Weight: A Systematic Review and Meta-Analysis. |journal=Toxics |date=21 June 2024 |volume=12 |issue=7 |page=446 |doi=10.3390/toxics12070446 |doi-access=free |pmid=39058098 |pmc=11280910 }}</ref><ref name=":14" /><ref name="Nzegwu">{{cite journal |last1=Nzegwu |first1=AW |last2=Dickerson |first2=AS |last3=Miller |first3=K |last4=Szpiro |first4=A |last5=Hipwell |first5=AE |last6=Elliot |first6=AJ |last7=Padula |first7=AM |last8=Dunlop |first8=AL |last9=Starling |first9=AP |last10=Ferrara |first10=A |last11=Breton |first11=CV |last12=Loftus |first12=CT |last13=McEvoy |first13=CT |last14=Dabelea |first14=D |last15=Koinis-Mitchell |first15=D |last16=Liang |first16=D |last17=Oken |first17=E |last18=Barrett |first18=ES |last19=Volk |first19=H |last20=Gern |first20=JE |last21=Stanford |first21=JB |last22=Herbstman |first22=JB |last23=Wu |first23=J |last24=Lyall |first24=K |last25=Trasande |first25=L |last26=Leve |first26=LD |last27=Karagas |first27=MR |last28=Pini |first28=N |last29=Wright |first29=RJ |last30=Nguyen |first30=RHN |last31=Schantz |first31=SL |last32=O'Connor |first32=TG |last33=Sathyanarayana |first33=S |last34=Karr |first34=CJ |last35=Enquobahrie |first35=DA |last36=ECHO Cohort |first36=Consortium |title=Gestational fine particulate matter exposure and perinatal outcomes in the ECHO cohort: Associations across pregnancy windows. |journal=Environmental Research |date=1 March 2026 |volume=292 |article-number=123587 |doi=10.1016/j.envres.2025.123587 |pmid=41443492 |pmc=12965624 |bibcode=2026ER....29223587N }}</ref> Smaller forms of particulate matter, including black carbon and microplastics, can cross the placental barrier and cause harms during placental development.<ref name="Johnson">{{cite journal |last1=Johnson |first1=NM |last2=Hoffmann |first2=AR |last3=Behlen |first3=JC |last4=Lau |first4=C |last5=Pendleton |first5=D |last6=Harvey |first6=N |last7=Shore |first7=R |last8=Li |first8=Y |last9=Chen |first9=J |last10=Tian |first10=Y |last11=Zhang |first11=R |title=Air pollution and children's health-a review of adverse effects associated with prenatal exposure from fine to ultrafine particulate matter. |journal=Environmental Health and Preventive Medicine |date=12 July 2021 |volume=26 |issue=1 |page=72 |doi=10.1186/s12199-021-00995-5 |doi-access=free |pmid=34253165 |pmc=8274666 |bibcode=2021EHPM...26...72J }}</ref><ref>{{cite news |last1=Carrington |first1=Damian |title=Air pollution particles found on foetal side of placentas – study |url=https://www.theguardian.com/environment/2019/sep/17/air-pollution-particles-found-on-foetal-side-of-placentas-study |access-date=16 April 2026 |work=The Guardian |date=17 September 2019}}</ref> Particulate matter from wildfire smoke leads to alterations in placental function and negative outcomes in pregnancy.<ref name="Basilio"/>

Studies that attempt to further associate the effects of particulate matter with exposure during specific trimesters have shown varied results.<ref name=":16" /><ref name="Parasin" /> Perinatal exposure is associated with lifelong health outcomes.<ref name="Gheissari">{{cite journal |last1=Gheissari |first1=R |last2=Liao |first2=J |last3=Garcia |first3=E |last4=Pavlovic |first4=N |last5=Gilliland |first5=FD |last6=Xiang |first6=AH |last7=Chen |first7=Z |title=Health Outcomes in Children Associated with Prenatal and Early-Life Exposures to Air Pollution: A Narrative Review. |journal=Toxics |date=8 August 2022 |volume=10 |issue=8 |page=458 |doi=10.3390/toxics10080458 |doi-access=free |pmid=36006137 |pmc=9415268 |bibcode=2022Toxic..10..458G }}</ref>

====Wildfire smoke effects====

Smoke from wildfires may more seriously affect sensitive groups such as the elderly, children, pregnant women, and people with lung, and cardiovascular disease.<ref name="Cascio">{{cite journal |last1=Cascio |first1=WE |title=Wildland fire smoke and human health. |journal=The Science of the Total Environment |date=15 May 2018 |volume=624 |pages=586–595 |doi=10.1016/j.scitotenv.2017.12.086 |pmid=29272827 |pmc=6697173 |bibcode=2018ScTEn.624..586C }}</ref><ref name="Basilio" /> Wildfires are associated with increased emergency department visits due to particulate matter exposure, as well as an increased risk of asthma related events.<ref>{{cite journal | vauthors = Reid CE, Considine EM, Watson GL, Telesca D, Pfister GG, Jerrett M | title = Associations between respiratory health and ozone and fine particulate matter during a wildfire event | journal = Environment International | volume = 129 | pages = 291–298 | date = August 2019 | pmid = 31146163 | doi = 10.1016/j.envint.2019.04.033 | doi-access = free | bibcode = 2019EnInt.129..291R }}</ref> Particulate matter from wildfires can be a triggering factor of acute coronary events such as ischemic heart disease.<ref name="Cascio"/> PM{{sub|2.5}} from wildfires is linked to an increased risk of hospitalizations for cardiopulmonary diseases.<ref>{{cite journal | vauthors = DeFlorio-Barker S, Crooks J, Reyes J, Rappold AG | title = Cardiopulmonary Effects of Fine Particulate Matter Exposure among Older Adults, during Wildfire and Non-Wildfire Periods, in the United States 2008–2010 | journal = Environmental Health Perspectives | volume = 127 | issue = 3 | page = 37006 | date = March 2019 | article-number = 037006 | pmid = 30875246 | pmc = 6768318 | doi = 10.1289/EHP3860 | bibcode = 2019EnvHP.127c7006D }}</ref> Evidence also suggests that wildfire smoke reduces mental performance.<ref>{{cite news |url=https://www.thestar.com/news/canada/2023/06/27/what-is-smoke-brain-how-air-pollution-can-harm-our-cognition-and-mental-health.html |newspaper=Toronto Star |date=27 June 2023 |first=Kevin |last=Jiang |title=What is 'smoke brain'? How air pollution can harm our cognition and mental health |access-date=3 July 2023 |archive-date=3 July 2023 |archive-url=https://web.archive.org/web/20230703161010/https://www.thestar.com/news/canada/2023/06/27/what-is-smoke-brain-how-air-pollution-can-harm-our-cognition-and-mental-health.html |url-status=live }}</ref>

==== Racial disparities ==== There have been many studies linking race to increased proximity to particulate matter emissions sources and adverse health effects such as asthma.<ref>{{cite journal |last1=Canaday |first1=FT |last2=Georas |first2=SN |last3=Croft |first3=DP |title=Examining the impact of air pollution, climate change, and social determinants of health on asthma and environmental justice. |journal=Current Opinion in Pulmonary Medicine |date=1 May 2024 |volume=30 |issue=3 |pages=276–280 |doi=10.1097/MCP.0000000000001065 |pmid=38411188 |pmc=10959677 }}</ref> Black populations are located disproportionately closer to areas of high PM output than White populations. Residential proximity to particulate emitting facilities increases exposure to PM2.5 and rates of illness and death.<ref name=":2">{{cite journal |last1=Mikati |first1=Ihab |last2=Benson |first2=Adam F. |last3=Luben |first3=Thomas J. |last4=Sacks |first4=Jason D. |last5=Richmond-Bryant |first5=Jennifer |title=Disparities in Distribution of Particulate Matter Emission Sources by Race and Poverty Status |journal=American Journal of Public Health |date=1 April 2018 |volume=108 |issue=4 |pages=480–485 |doi=10.2105/AJPH.2017.304297 |pmid=29470121 |pmc=5844406 }}</ref><ref name="Collins" /><ref name="Erqou">{{cite journal |last1=Erqou |first1=S |last2=Clougherty |first2=JE |last3=Olafiranye |first3=O |last4=Magnani |first4=JW |last5=Aiyer |first5=A |last6=Tripathy |first6=S |last7=Kinnee |first7=E |last8=Kip |first8=KE |last9=Reis |first9=SE |title=Particulate Matter Air Pollution and Racial Differences in Cardiovascular Disease Risk. |journal=Arteriosclerosis, Thrombosis, and Vascular Biology |date=April 2018 |volume=38 |issue=4 |pages=935–942 |doi=10.1161/ATVBAHA.117.310305 |pmid=29545240 |pmc=5864550 }}</ref><ref name="Yitshak-Sade">{{cite journal |last1=Yitshak-Sade |first1=Maayan |last2=Lane |first2=Kevin J. |last3=Fabian |first3=M. Patricia |last4=Kloog |first4=Itai |last5=Hart |first5=Jaime E. |last6=Davis |first6=Brigette |last7=Fong |first7=Kelvin C. |last8=Schwartz |first8=Joel D. |last9=Laden |first9=Francine |last10=Zanobetti |first10=Antonella |title=Race or racial segregation? Modification of the PM2.5 and cardiovascular mortality association |journal=PLOS ONE |date=27 July 2020 |volume=15 |issue=7 |article-number=e0236479 |doi=10.1371/journal.pone.0236479 |doi-access=free |pmid=32716950 |pmc=7384646 |bibcode=2020PLoSO..1536479Y |language=en |issn=1932-6203}}</ref> Multiple studies confirm that the burden of PM emissions is higher among populations that are non-White or living in poverty.<ref name=":2" /><ref name="Collins">{{cite journal |last1=Collins |first1=TW |last2=Grineski |first2=SE |title=Racial/Ethnic Disparities in Short-Term PM2.5 Air Pollution Exposures in the United States. |journal=Environmental Health Perspectives |date=August 2022 |volume=130 |issue=8 |page=87701 |doi=10.1289/EHP11479 |pmid=35983969 |pmc=9389641 |bibcode=2022EnvHP.130h7701C }}</ref><ref name="Cheeseman">{{cite journal |last1=Cheeseman |first1=MJ |last2=Ford |first2=B |last3=Anenberg |first3=SC |last4=Cooper |first4=MJ |last5=Fischer |first5=EV |last6=Hammer |first6=MS |last7=Magzamen |first7=S |last8=Martin |first8=RV |last9=van Donkelaar |first9=A |last10=Volckens |first10=J |last11=Pierce |first11=JR |title=Disparities in Air Pollutants Across Racial, Ethnic, and Poverty Groups at US Public Schools. |journal=GeoHealth |date=December 2022 |volume=6 |issue=12 |article-number=e2022GH000672 |doi=10.1029/2022GH000672 |pmid=36467256 |pmc=9714311 |bibcode=2022GHeal...6..672C }}</ref><ref name="PMID34908495">{{cite journal |last1=Liu |first1=J |last2=Clark |first2=LP |last3=Bechle |first3=MJ |last4=Hajat |first4=A |last5=Kim |first5=SY |last6=Robinson |first6=AL |last7=Sheppard |first7=L |last8=Szpiro |first8=AA |last9=Marshall |first9=JD |title=Disparities in Air Pollution Exposure in the United States by Race/Ethnicity and Income, 1990-2010. |journal=Environmental Health Perspectives |date=December 2021 |volume=129 |issue=12 |page=127005 |doi=10.1289/EHP8584 |pmid=34908495 |pmc=8672803 |bibcode=2021EnvHP.129l7005L }}</ref> Socioeconomic conditions are not sufficient to explain these differences: disparities for Blacks are more pronounced than disparities on the basis of income.<ref name=":2" /><ref name="PMID34908495"/>

In the United States, this disproportionality is attributed by scholars to racial housing segregation and inequalities in toxic exposures,<ref name=":1">{{cite journal |last1=Smiley |first1=Kevin T. |title=Racial and Environmental Inequalities in Spatial Patterns in Asthma Prevalence in the US South |journal=Southeastern Geographer |date=2019 |volume=59 |issue=4 |pages=389–402 |doi=10.1353/sgo.2019.0031 |id={{Project MUSE|736789}} }}</ref> a longstanding environmental justice problem linked to the practice of historic redlining.<ref name=":3" /><ref name="Bramble">{{cite journal |last1=Bramble |first1=Kaya |last2=Blanco |first2=Magali N. |last3=Doubleday |first3=Annie |last4=Gassett |first4=Amanda J. |last5=Hajat |first5=Anjum |last6=Marshall |first6=Julian D. |last7=Sheppard |first7=Lianne |title=Exposure Disparities by Income, Race and Ethnicity, and Historic Redlining Grade in the Greater Seattle Area for Ultrafine Particles and Other Air Pollutants |journal=Environmental Health Perspectives |date=July 2023 |volume=131 |issue=7 |article-number=077004 |doi=10.1289/EHP11662 |pmid=37404015 |pmc=10321236 |bibcode=2023EnvHP.131g7004B |language=en |issn=0091-6765}}</ref> Health effects are further worsened because "health care occurs in the context of broader historic and contemporary social and economic inequality and persistent racial and ethnic discrimination in many sectors of American life".<ref>{{cite journal |title=Erratum: Eur. Phys. J. C.22, 695–705 (2002) – DOI 10.1007/s100520100827 Published online: 7 December 2001 |journal=The European Physical Journal C |date=August 2002 |volume=24 |issue=4 |pages=665–666 |doi=10.1007/s10052-002-0987-x |bibcode=2002EPJC...24..665. }}</ref>

One example is an area of Southeastern Louisiana, colloquially dubbed 'Cancer Alley' for its high concentration of cancer related deaths due to neighboring chemical plants. Cancer Alley is a majority African American community, with the neighborhood nearest to the plant being 90% Black. Long-term health effects of living in high PM concentrations have increased both illness and mortality rates, which were further worsened by COVID-19. Such outcomes reflect a history of racism.<ref name="Hernandez">{{cite news |last1=Hernandez |first1=Alina |title=Environmental Law Clinic analysis: Air pollution in Louisiana tied to higher COVID-19 impact |url=https://law.tulane.edu/environmental-law-clinic-analysis-air-pollution-louisiana-tied-higher-covid-19-impact |access-date=15 April 2026 |work=Tulane University Law School |language=en}}</ref><ref name=":3">{{cite news |last1=Jervis |first1=Rick |last2=Gomez |first2=Alan |title=Racism turned their neighborhood into 'Cancer Alley.' Now they're dying from COVID-19 |url=https://www.usatoday.com/in-depth/news/nation/2020/10/12/covid-racism-kills-black-americans-living-near-toxic-plants/3498180001/ |work=USA Today |date=12 October 2020 |access-date=11 February 2021 |archive-date=25 January 2021 |archive-url=https://web.archive.org/web/20210125163825/https://www.usatoday.com/in-depth/news/nation/2020/10/12/covid-racism-kills-black-americans-living-near-toxic-plants/3498180001/ |url-status=live }}</ref><ref>{{cite journal |last1=Hu |first1=G |last2=Hamovit |first2=N |last3=Croft |first3=K |last4=Roberts |first4=JD |last5=Niemeier |first5=D |title=Assessing inequities underlying racial disparities of COVID-19 mortality in Louisiana parishes. |journal=Proceedings of the National Academy of Sciences of the United States of America |date=5 July 2022 |volume=119 |issue=27 |article-number=e2123533119 |doi=10.1073/pnas.2123533119 |doi-access=free |pmid=35759671 |pmc=9271191 |bibcode=2022PNAS..11923533H }}</ref>

== Vegetation effects == {{expand section|date=February 2024}} thumb|right|300px|Dendrochronology studies history through the rings of trees and the chemistry of wood.<ref name="Tegel">{{cite journal |last1=Tegel |first1=Willy |last2=Muigg |first2=Bernhard |last3=Skiadaresis |first3=Georgios |last4=Vanmoerkerke |first4=Jan |last5=Seim |first5=Andrea |title=Dendroarchaeology in Europe |journal=Frontiers in Ecology and Evolution |date=16 February 2022 |volume=10 |article-number=823622 |doi=10.3389/fevo.2022.823622 |doi-access=free |bibcode=2022FrEEv..1023622T |language=English |issn=2296-701X}}</ref> The release of particulate matter into the environment affects both terrestrial and aquatic ecosystems. Particulate matter can settle from the air onto plants, ground, and water. Ultrafine particles can enter plants via both leaves and root systems, travel throughout plants, and affect their physical and chemical processes. The deposition of trace elements from pollution into the rings of trees can be used by dendrochronologists to reconstruct a pollution history, a historical record of changes in soils, sediments and the atmosphere.<ref name="Ballikaya">{{cite journal |last1=Ballikaya |first1=Paula |last2=Marshall |first2=John |last3=Cherubini |first3=Paolo |title=Can tree-ring chemistry be used to monitor atmospheric nanoparticle contamination over time? |journal=Atmospheric Environment |date=1 January 2022 |volume=268 |article-number=118781 |doi=10.1016/j.atmosenv.2021.118781 |bibcode=2022AtmEn.26818781B |issn=1352-2310}}</ref><ref>{{cite journal |last1=Monaci |first1=F |last2=Baroni |first2=D |title=Leaves and Tree Rings as Biomonitoring Archives of Atmospheric Mercury Deposition: An Ecophysiological Perspective. |journal=Plants (Basel, Switzerland) |date=22 April 2025 |volume=14 |issue=9 |page=1275 |doi=10.3390/plants14091275 |doi-access=free |pmid=40364304 |pmc=12073167 |bibcode=2025Plnts..14.1275M }}</ref>

Particulate matter can physically block sunlight from entering leaves, preventingh photosynthesis.<ref name="Roy2024">{{cite journal |last1=Roy |first1=A |last2=Mandal |first2=M |last3=Das |first3=S |last4=Popek |first4=R |last5=Rakwal |first5=R |last6=Agrawal |first6=GK |last7=Awasthi |first7=A |last8=Sarkar |first8=A |title=The cellular consequences of particulate matter pollutants in plants: Safeguarding the harmonious integration of structure and function. |journal=The Science of the Total Environment |date=1 March 2024 |volume=914 |article-number=169763 |doi=10.1016/j.scitotenv.2023.169763 |pmid=38181950 |bibcode=2024ScTEn.91469763R }}</ref> It can clog stomatal openings of plants and interfere with photosynthesis and transpiration functions.<ref name="ChenS">{{cite journal |last1=Chen |first1=Siqi |last2=Yu |first2=Hua |last3=Xu |first3=Liang |last4=Fei |first4=Fangmin |last5=Song |first5=Yaobin |last6=Dong |first6=Ming |last7=Li |first7=Weijun |title=Characterizing accumulation and negative effects of aerosol particles on the leaves of urban trees |journal=Environmental Pollution |date=1 January 2024 |volume=340 |issue=Pt 1 |article-number=122812 |doi=10.1016/j.envpol.2023.122812 |pmid=37898428 |bibcode=2024EPoll.34022812C |url=https://www.sciencedirect.com/science/article/abs/pii/S0269749123018146 |issn=0269-7491}}</ref><ref name="Chen2024">{{cite journal |last1=Chen |first1=S |last2=Fei |first2=F |last3=Song |first3=Y |last4=Dong |first4=M |last5=Wu |first5=A |last6=Yu |first6=H |title=Composition and Effects of Aerosol Particles Deposited on Urban Plant Leaves in Terrestrial and Aquatic Habitats. |journal=Plants (Basel, Switzerland) |date=31 October 2024 |volume=13 |issue=21 |page=3056 |doi=10.3390/plants13213056 |doi-access=free |pmid=39519990 |pmc=11548794 |bibcode=2024Plnts..13.3056C }}</ref> Particulate matter can damage plant cells<ref>{{cite journal |last1=Kim |first1=Kanghee |last2=Lee |first2=Jee Won |last3=Kim |first3=Hyung Min |last4=Park |first4=Chang-Beom |title=Growth inhibition in lettuce callus exposed to particulate matter: Cellular injury linked to intracellular accumulation |journal=Environmental Pollution |date=15 December 2025 |volume=387 |article-number=127288 |doi=10.1016/j.envpol.2025.127288 |pmid=41109622 |bibcode=2025EPoll.38727288K |url=https://www.sciencedirect.com/science/article/pii/S0269749125016628 |issn=0269-7491}}</ref> and stunt or kill some plant species.<ref name="Roy2024" />

Damage from particulate matter can reduce productivity of crops.<ref name="Fang2026">{{cite journal |last1=Fang |first1=Qiang |last2=Huang |first2=Yanan |last3=Singh |first3=Ashbindu |last4=Qu |first4=John J. |last5=Hao |first5=Xianjun |last6=Xu |first6=Chenyang |title=The composite effects of air pollution on yield |journal=npj Sustainable Agriculture |date=13 April 2026 |volume=4 |issue=1 |page=36 |doi=10.1038/s44264-026-00152-x |bibcode=2026npjSA...4...36F |url=https://www.nature.com/articles/s44264-026-00152-x |language=en |issn=2731-9202}}</ref><ref>{{cite news |title=Pollution and crops |url=https://news.stanford.edu/stories/2022/06/pollution-and-crops |access-date=15 April 2026 |work=Stanford Report |date=June 1, 2022 |language=en}}</ref><ref name="Lobell">{{cite journal |last1=Lobell |first1=David B. |last2=Di Tommaso |first2=Stefania |last3=Burney |first3=Jennifer A. |title=Globally ubiquitous negative effects of nitrogen dioxide on crop growth |journal=Science Advances |date=June 2022 |volume=8 |issue=22 |article-number=eabm9909 |doi=10.1126/sciadv.abm9909 |pmid=35648854 |pmc=9159569 |bibcode=2022SciA....8M9909L }}</ref> Plants can absorb and retain particulate matter, removing it from the air and improving the quality of the air we breathe.<ref name="Diener">{{cite journal |last1=Diener |first1=Arnt |last2=Mudu |first2=Pierpaolo |title=How can vegetation protect us from air pollution? A critical review on green spaces' mitigation abilities for air-borne particles from a public health perspective - with implications for urban planning |journal=Science of the Total Environment |date=20 November 2021 |volume=796 |article-number=148605 |doi=10.1016/j.scitotenv.2021.148605 |pmid=34271387 |bibcode=2021ScTEn.79648605D |issn=0048-9697}}</ref> However, this also means that particulate matter such as heavy metals can contaminate plants such as leafy vegetables above safe levels for human consumption.<ref name="Noh">{{cite journal |last1=Noh |first1=K |last2=Thi |first2=LT |last3=Jeong |first3=BR |title=Particulate matter in the cultivation area may contaminate leafy vegetables with heavy metals above safe levels in Korea. |journal=Environmental Science and Pollution Research International |date=September 2019 |volume=26 |issue=25 |pages=25762–25774 |doi=10.1007/s11356-019-05825-4 |pmid=31267404 |pmc=6717186 |bibcode=2019ESPR...2625762N }}</ref>

== Climate effects == {{Update|section|date=April 2026}} {{technical|section|date=April 2026}} thumb|Aerosols have a cooling effect that is small compared to the radiative forcing (warming effect) of greenhouse gases.<ref name="ESSD_2022">{{cite journal |last1=Forster |first1=Piers M. |last2=Smith |first2=Christopher J. |last3=Walsh |first3=Tristram |last4=Lamb |first4=William F. |last5=Lamboll |first5=Robin |display-authors=4 |title=Indicators of Global Climate Change 2022: annual update of large-scale indicators of the state of the climate system and human influence |journal=Earth System Science Data |date=2023 |volume=15 |issue=6 |pages=2295–2327 |publisher=Copernicus Programme |doi=10.5194/essd-15-2295-2023 |bibcode=2023ESSD...15.2295F |doi-access=free }} Fig. 2(a).</ref> Atmospheric aerosols affect the climate of the Earth by changing the amount of incoming solar radiation and outgoing terrestrial longwave radiation retained in the Earth's system. This occurs through several distinct mechanisms which are split into direct, indirect<ref name="Haywood2000">{{cite journal |last1=Haywood |first1=James |last2=Boucher |first2=Olivier |title=Estimates of the direct and indirect radiative forcing due to tropospheric aerosols: A review |journal=Reviews of Geophysics |date=November 2000 |volume=38 |issue=4 |pages=513–543 |doi=10.1029/1999RG000078 |bibcode=2000RvGeo..38..513H }}</ref><ref name="Twomey1977">{{cite journal| vauthors = Twomey S |year=1977|title=The influence of pollution on the shortwave albedo of clouds|journal=Journal of the Atmospheric Sciences|volume= 34| issue=7| pages=1149–1152| doi=10.1175/1520-0469(1977)034<1149:TIOPOT>2.0.CO;2|bibcode = 1977JAtS...34.1149T |doi-access=free}}</ref> and semi-direct aerosol effects. The aerosol climate effects are the biggest source of uncertainty in future climate predictions.<ref name="Forster2007" /> The Intergovernmental Panel on Climate Change (IPCC) stated in 2001:<ref>{{cite web| url =http://www.grida.no/climate/ipcc_tar/wg1/237.htm#678| archive-url =https://web.archive.org/web/20020228024246/http://www.grida.no/climate/ipcc_tar/wg1/237.htm#678| archive-date =28 February 2002| title =6.7.8 Discussion of Uncertainties| website =IPCC Third Assessment Report – Climate Change 2001| access-date =14 July 2012}}</ref><blockquote>While the radiative forcing due to greenhouse gases may be determined to a reasonably high degree of accuracy... the uncertainties relating to aerosol radiative forcings remain large, and rely to a large extent on the estimates from global modeling studies that are difficult to verify at the present time.</blockquote>

===Aerosol radiative=== [[File:Modis aerosol optical depth.png|thumb|Global aerosol optical thickness. The aerosol scale (yellow to dark reddish-brown) indicates the relative amount of particles that absorb sunlight.]] [[File: MODAL2 M AER OD.ogv|thumb|Average monthly aerosol amounts around the world, observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite.]]

====Direct==== [[File:Cloud 3.JPG|thumb|Particulates in the air causing shades of orange, yellow, pink, and grey in Mumbai during sunset]] thumb|Italian city polluted by particulates and optic air detector (laser) The direct aerosol effect consists of any direct interaction of radiation with atmospheric aerosols, such as absorption or scattering. It affects both short and longwave radiation to produce a net negative radiative forcing.<ref>{{cite journal | vauthors = Charlson RJ, Schwartz SE, Hales JM, Cess RD, Coakley JA, Hansen JE, Hofmann DJ | title = Climate forcing by anthropogenic aerosols | journal = Science | volume = 255 | issue = 5043 | pages = 423–30 | date = January 1992 | pmid = 17842894 | doi = 10.1126/science.255.5043.423 | bibcode = 1992Sci...255..423C }}</ref> The magnitude of the resultant radiative forcing due to the direct effect of an aerosol is dependent on the albedo of the underlying surface, as this affects the net amount of radiation absorbed or scattered to space. For example, if a highly scattering aerosol is above a surface of low albedo it has a greater radiative forcing than if it was above a surface of high albedo. The converse is true of absorbing aerosol, with the greatest radiative forcing arising from a highly absorbing aerosol over a surface of high albedo.<ref name="Haywood2000" /> The direct aerosol effect is a first-order effect and is therefore classified as a radiative forcing by the IPCC.<ref name="Forster2007">{{cite book|vauthors=Forster P, Ramaswamy V, Artaxo P, Berntsen T, Betts R, Fahey DW, Haywood J|chapter=Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change in Climate Change 2007: The Physical Science Basis|veditors=Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL|pages=129–234|publisher=Cambridge University Press|location=Cambridge, United Kingdom and New York, NY, US|chapter-url=http://elib.dlr.de/51416/|title=Changes in Atmospheric Constituents and in Radiative Forcing|display-authors=etal|date=October 2007|access-date=12 July 2012|archive-date=19 December 2013|archive-url=https://web.archive.org/web/20131219025955/http://elib.dlr.de/51416/|url-status=live}}</ref> The interaction of an aerosol with radiation is quantified by the single-scattering albedo (SSA), the ratio of scattering alone to scattering plus absorption (''extinction'') of radiation by a particle. The SSA tends to unity if scattering dominates, with relatively little absorption, and decreases as absorption increases, becoming zero for infinite absorption. For example, the sea-salt aerosol has an SSA of 1, as a sea-salt particle only scatters, whereas soot has an SSA of 0.23, showing that it is a major atmospheric aerosol absorber.{{citation needed|date=March 2023}}

==== Indirect ==== The Indirect aerosol effect consists of any change to the Earth's radiative budget due to the modification of clouds by atmospheric aerosols and consists of several distinct effects. Cloud droplets form onto pre-existing aerosol particles, known as cloud condensation nuclei (CCN). Droplets condensing around human-produced aerosols such as found in particulate pollution tend to be smaller and more numerous than those forming around aerosol particles of natural origin (such as windblown dust).

For any given meteorological conditions, an increase in CCN leads to an increase in the number of cloud droplets. This leads to more scattering of shortwave radiation i.e. an increase in the albedo of the cloud, known as the cloud albedo effect, First indirect effect or Twomey effect.<ref name="Twomey1977" /> Evidence supporting the cloud albedo effect has been observed from the effects of ship exhaust plumes<ref>{{cite journal |last1=Ackerman |first1=Andrew S. |last2=Toon |first2=Owen B. |last3=Taylor |first3=Jonathan P. |last4=Johnson |first4=Doug W. |last5=Hobbs |first5=Peter V. |last6=Ferek |first6=Ronald J. |title=Effects of Aerosols on Cloud Albedo: Evaluation of Twomey's Parameterization of Cloud Susceptibility Using Measurements of Ship Tracks |journal=Journal of the Atmospheric Sciences |date=August 2000 |volume=57 |issue=16 |pages=2684–2695 |doi=10.1175/1520-0469(2000)057<2684:EOAOCA>2.0.CO;2 |bibcode=2000JAtS...57.2684A }}</ref> and biomass burning<ref>{{cite journal |last1=Kaufman |first1=Yoram J. |last2=Fraser |first2=Robert S. |title=The Effect of Smoke Particles on Clouds and Climate Forcing |journal=Science |date=12 September 1997 |volume=277 |issue=5332 |pages=1636–1639 |doi=10.1126/science.277.5332.1636 }}</ref> on cloud albedo compared to ambient clouds. The Cloud albedo aerosol effect is a first order effect and therefore classified as a radiative forcing by the IPCC.<ref name="Forster2007" />

An increase in cloud droplet number due to the introduction of aerosol acts to reduce the cloud droplet size, as the same amount of water is divided into more droplets. This has the effect of suppressing precipitation, increasing the cloud lifetime, known as the cloud lifetime aerosol effect, second indirect effect or Albrecht effect.<ref name="Forster2007" /> This has been observed as the suppression of drizzle in ship exhaust plume compared to ambient clouds,<ref>{{cite journal | vauthors = Ferek RJ, Garrett T, Hobbs PV, Strader S, Johnson D, Taylor JP, Nielsen K, Ackerman AS, Kogan Y, Liu Q, Albrecht BA | year = 2000 | title = Drizzle Suppression in Ship Tracks | journal = Journal of the Atmospheric Sciences | volume = 57 | issue = 16 | pages = 2707–2728 | doi = 10.1175/1520-0469(2000)057<2707:DSIST>2.0.CO;2 | bibcode = 2000JAtS...57.2707F | display-authors = etal | hdl = 10945/46780 }}</ref> and inhibited precipitation in biomass burning plumes.<ref>{{cite journal| vauthors = Rosenfeld D | year= 1999| title=TRMM observed first direct evidence of smoke from forest fires inhibiting rainfall|journal=Geophysical Research Letters|volume=26 |issue=20 |pages= 3105–3108|doi=10.1029/1999GL006066 |bibcode=1999GeoRL..26.3105R|doi-access=free}}</ref> This cloud lifetime effect is classified as a climate feedback (rather than a radiative forcing) by the IPCC due to the interdependence between it and the hydrological cycle.<ref name="Forster2007" /> However, it has previously been classified as a negative radiative forcing.<ref name="Hansen1997">{{cite journal| vauthors = Hansen J, Sato M, Ruedy R | year = 1997|title=Radiative forcing and climate response|journal = Journal of Geophysical Research |volume=102 |issue=D6 | pages= 6831–6864 | doi=10.1029/96JD03436 | bibcode=1997JGR...102.6831H| doi-access=free }}</ref>

====Semi-direct==== The Semi-direct effect concerns any radiative effect caused by absorbing atmospheric aerosol such as soot, apart from direct scattering and absorption, which is classified as the direct effect. It encompasses many individual mechanisms, and in general is more poorly defined and understood than the direct and indirect aerosol effects. For instance, if absorbing aerosols are present in a layer aloft in the atmosphere, they can heat surrounding air which inhibits the condensation of water vapour, resulting in less cloud formation.<ref>{{cite journal | vauthors = Ackerman AS, Toon OB, Stevens DE, Heymsfield AJ, Ramanathan V, Welton EJ | title = Reduction of tropical cloudiness by soot | journal = Science | volume = 288 | issue = 5468 | pages = 1042–7 | date = May 2000 | pmid = 10807573 | doi = 10.1126/science.288.5468.1042 | bibcode = 2000Sci...288.1042A }}</ref> Additionally, heating a layer of the atmosphere relative to the surface results in a more stable atmosphere due to the inhibition of atmospheric convection. This inhibits the convective uplift of moisture,<ref>{{cite journal | vauthors = Koren I, Kaufman YJ, Remer LA, Martins JV | title = Measurement of the effect of Amazon smoke on inhibition of cloud formation | journal = Science | volume = 303 | issue = 5662 | pages = 1342–5 | date = February 2004 | pmid = 14988557 | doi = 10.1126/science.1089424 | bibcode = 2004Sci...303.1342K }}</ref> which in turn reduces cloud formation. The heating of the atmosphere aloft also leads to a cooling of the surface, resulting in less evaporation of surface water. The effects described here all lead to a reduction in cloud cover i.e. an increase in planetary albedo. The semi-direct effect classified as a climate feedback) by the IPCC due to the interdependence between it and the hydrological cycle.<ref name="Forster2007" /> However, it has previously been classified as a negative radiative forcing.<ref name="Hansen1997" />

===Specific aerosol roles===

==== Sulfate ==== {{See also|Global dimming|Stratospheric aerosol injection}} Sulfate aerosols are mostly inorganic sulfur compounds like {{chem|SO|4|2-}}, {{chem|HSO|4|−}} and {{chem|H|2|SO|4|}},<ref>{{Cite journal |last1=Riva |first1=Matthieu |last2=Chen |first2=Yuzhi |last3=Zhang |first3=Yue |last4=Lei |first4=Ziying |last5=Olson |first5=Nicole E. |last6=Boyer |first6=Hallie C. |last7=Narayan |first7=Shweta |last8=Yee |first8=Lindsay D. |last9=Green |first9=Hilary S. |last10=Cui |first10=Tianqu |last11=Zhang |first11=Zhenfa |last12=Baumann |first12=Karsten |last13=Fort |first13=Mike |last14=Edgerton |first14=Eric |last15=Budisulistiorini |first15=Sri H. |date=6 August 2019 |title=Increasing Isoprene Epoxydiol-to-Inorganic Sulfate Aerosol Ratio Results in Extensive Conversion of Inorganic Sulfate to Organosulfur Forms: Implications for Aerosol Physicochemical Properties |journal=Environmental Science & Technology |language=en |volume=53 |issue=15 |pages=8682–8694 |doi=10.1021/acs.est.9b01019 |pmc=6823602 |pmid=31335134|bibcode=2019EnST...53.8682R }}</ref> which are mainly produced when sulfur dioxide reacts with water vapor to form gaseous sulfuric acid and various salts (often through an oxidation reaction in the clouds), which are then thought to experience hygroscopic growth and coagulation and then shrink through evaporation.<ref>{{cite book |last1=Seinfeld |first1=John H. |last2=Pandis |first2=Spyros N. |title=Atmospheric Chemistry and Physics: From Air Pollution to Climate Change |date=2016 |publisher=John Wiley & Sons |isbn=978-1-119-22116-6 }}{{page needed|date=August 2025}}</ref><ref name=":0222" /> Some of them are biogenic (typically produced via atmospheric chemical reactions with dimethyl sulfide from mostly marine plankton<ref>{{Cite journal |last1=Charlson |first1=Robert J. |last2=Wigley |first2=Tom M. L. |date=1994 |title=Sulfate Aerosol and Climatic Change |journal=Scientific American |volume=270 |issue=2 |pages=48–57 |doi=10.1038/scientificamerican0294-48 |jstor=24942590 |bibcode=1994SciAm.270b..48C }}</ref>) or geological via volcanoes or weather-driven from wildfires and other natural combustion events,<ref name=":0222">{{Cite journal |last1=Legras |first1=Bernard |last2=Duchamp |first2=Clair |last3=Sellitto |first3=Pasquale |last4=Podglajen |first4=Aurélien |last5=Carboni |first5=Elisa |last6=Siddans |first6=Richard |last7=Grooß |first7=Jens-Uwe |last8=Khaykin |first8=Sergey |last9=Ploeger |first9=Felix |date=23 November 2022 |title=The evolution and dynamics of the Hunga Tonga plume in the stratosphere |journal=Atmospheric Chemistry and Physics |language=English |volume=22 |issue=22 |pages=14957–14970 |doi=10.5194/acp-22-14957-2022 |doi-access=free }}</ref> but in the recent decades anthropogenic sulfate aerosols produced through combustion of fossil fuels with a high sulfur content, primarily coal and certain less-refined fuels, like aviation and bunker fuel, had dominated.<ref name=":4">{{Cite web |last=Allen |first=Bob |date=6 April 2015 |title=Atmospheric Aerosols: What Are They, and Why Are They So Important? |url=http://www.nasa.gov/centers/langley/news/factsheets/Aerosols.html |access-date=17 April 2023 |website=NASA |archive-date=14 May 2022 |archive-url=https://web.archive.org/web/20220514055232/https://www.nasa.gov/centers/langley/news/factsheets/Aerosols.html |url-status=live }}</ref> By 1990, global human-caused emissions of sulfur into the atmosphere became "at least as large" as ''all'' natural emissions of sulfur-containing compounds '''combined''', and were at least 10 times more numerous than the natural aerosols in the most polluted regions of Europe and North America,<ref name="IPCC_FAR">IPCC, 1990: [https://www.ipcc.ch/site/assets/uploads/2018/03/ipcc_far_wg_I_chapter_01.pdf Chapter 1: Greenhouse Gases and Aerosols] {{Webarchive|url=https://web.archive.org/web/20230526153240/https://www.ipcc.ch/site/assets/uploads/2018/03/ipcc_far_wg_I_chapter_01.pdf |date=26 May 2023 }} [R.T. Watson, H. Rodhe, H. Oeschger and U. Siegenthaler]. In: [https://www.ipcc.ch/site/assets/uploads/2018/03/ipcc_far_wg_I_full_report.pdf Climate Change: The IPCC Scientific Assessment] {{Webarchive|url=https://web.archive.org/web/20230615205605/https://www.ipcc.ch/site/assets/uploads/2018/03/ipcc_far_wg_I_full_report.pdf |date=15 June 2023 }} [J.T.Houghton, G.J.Jenkins and J.J.Ephraums (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 31–34,</ref> where they accounted for 25% or more of all air pollution.<ref name="EPAHealth" /> This led to acid rain,<ref name="EPASurface">{{Cite web|title=Effects of Acid Rain – Surface Waters and Aquatic Animals|url=http://www.epa.gov/acidrain/effects/surface_water.html|archive-url=https://web.archive.org/web/20090514121649/http://www.epa.gov/acidrain/effects/surface_water.html|archive-date=14 May 2009|website=US EPA |date=8 September 2006 }}</ref><ref>{{cite journal |last1=Likens |first1=G. E. |last2=Driscoll |first2=C. T. |last3=Buso |first3=D. C. |title=Long-Term Effects of Acid Rain: Response and Recovery of a Forest Ecosystem |journal=Science |date=12 April 1996 |volume=272 |issue=5259 |pages=244–246 |doi=10.1126/science.272.5259.244 |bibcode=1996Sci...272..244L }}</ref> and also contributed to heart and lung conditions<ref name="EPAHealth">[https://www.epa.gov/acidrain/effects-acid-rain#health Effects of Acid Rain – Human Health] . Epa.gov (2 June 2006). Retrieved on 9 February 2013.</ref> and even the risk of preterm birth and low birth weight.<ref>{{Cite journal |last1=Wang |first1=X. |last2=Ding |first2=H. |last3=Ryan |first3=L. |last4=Xu |first4=X. |date=May 1997 |title=Association between air pollution and low birth weight: a community-based study |journal=Environmental Health Perspectives |volume=105 |issue=5 |pages=514–20 |pmc=1469882 |pmid=9222137 |doi=10.1289/ehp.97105514 |bibcode=1997EnvHP.105..514W }}</ref> Sulfate pollution also has a complex relationship with NOx pollution and ozone, reducing the also harmful ground-level ozone, yet capable of damaging the stratospheric ozone layer as well.<ref>{{cite journal |title=Effect of sulfate aerosol on tropospheric NOx and ozone budgets: Model simulations and TOPSE evidence |last=Tie |first=X. |year=2003 |journal=J. Geophys. Res. |volume=108 |issue=D4 |page=8364 |doi=10.1029/2001JD001508 |bibcode=2003JGRD..108.8364T |display-authors=etal |article-number=2001JD001508 |doi-access=free }}</ref> thumb|left|Stratospheric sulfates from volcanic emissions cause transient cooling; the purple line showing sustained cooling is from tropospheric sulfate pollution. Once the problem became clear, the efforts to remove this pollution through flue-gas desulfurization measures and other pollution controls were largely successful,<ref name="CAA01">{{cite press release |title=Clean Air Act Reduces Acid Rain In Eastern United States |url=https://www.sciencedaily.com/releases/1998/09/980928072644.htm |work=ScienceDaily |publisher=Penn State |date=28 September 1998 }}</ref> reducing their prevalence by 53% and causing healthcare savings valued at $50 billion annually in the United States alone.<ref>{{cite web | access-date=17 March 2007 | archive-date=17 March 2007 | archive-url=https://web.archive.org/web/20070317212933/http://www.epa.gov/airtrends/econ-emissions.html | url=http://www.epa.gov/airtrends/econ-emissions.html | title=Air Emissions Trends – Continued Progress Through 2005 | publisher=U.S. Environmental Protection Agency | date=8 July 2014}}</ref><ref name="EPAHealth" /><ref>{{Cite web|last1=Moses|first1=Elizabeth|last2=Cardenas|first2=Beatriz|last3=Seddon|first3=Jessica|date=25 February 2020|title=The Most Successful Air Pollution Treaty You've Never Heard Of|url=https://www.wri.org/insights/most-successful-air-pollution-treaty-youve-never-heard|language=en|access-date=28 June 2023|archive-date=8 June 2023|archive-url=https://web.archive.org/web/20230608092959/https://www.wri.org/insights/most-successful-air-pollution-treaty-youve-never-heard|url-status=live}}</ref> Yet, around the same time, research had shown that sulfate aerosols were affecting both the visible light received by the Earth and its surface temperature,<ref>{{cite journal|author1=Stanhill, G. |author2=S. Cohen|title=Global dimming: a review of the evidence for a widespread and significant reduction in global radiation with discussion of its probable causes and possible agricultural consequences | journal=Agricultural and Forest Meteorology|volume=107|year=2001|issue=4 |doi=10.1016/S0168-1923(00)00241-0|pages=255–278 |bibcode=2001AgFM..107..255S}}</ref> and as the so-called global dimming) began to reverse in the 1990s in line with the reduced anthropogenic sulfate pollution,<ref>{{cite book |doi=10.1016/b978-0-12-821575-3.00032-3 |chapter=Changes in the Sun's radiation |title=Climate Change |date=2021 |last1=Cohen |first1=Shabtai |last2=Stanhill |first2=Gerald |pages=687–709 |isbn=978-0-12-821575-3 }}</ref><ref>{{cite news|url=http://www.nasa.gov/centers/goddard/news/topstory/2007/aerosol_dimming.html|title=Global 'Sunscreen' Has Likely Thinned, Report NASA Scientists|publisher=NASA|date=15 March 2007|access-date=28 June 2023|archive-date=22 December 2018|archive-url=https://web.archive.org/web/20181222142212/https://www.nasa.gov/centers/goddard/news/topstory/2007/aerosol_dimming.html}}</ref><ref>{{cite news|year=2017|title=A bright sun today? It's down to the atmosphere|newspaper=The Guardian|url=https://www.theguardian.com/news/2017/mar/21/a-bright-sun-today-its-down-to-the-atmosphere|access-date=19 May 2017|archive-date=20 May 2017|archive-url=https://web.archive.org/web/20170520010323/https://www.theguardian.com/news/2017/mar/21/a-bright-sun-today-its-down-to-the-atmosphere|url-status=live}}</ref> climate change accelerated.<ref name="IPCC_WGI_Ch11">{{cite book |title=Climate Change 2021 – the Physical Science Basis |chapter=Global Carbon and Other Biogeochemical Cycles and Feedbacks |date=2023 |pages=673–816 |doi=10.1017/9781009157896.007 |isbn=978-1-009-15789-6 |url=https://oceanrep.geomar.de/54719/1/IPCC_AR6_WGI_Chapter_05.pdf |author=Intergovernmental Panel on Climate Change }}</ref> As of 2021, state-of-the-art CMIP6 models estimate that total cooling from the currently present aerosols is between {{convert|0.1|C-change|F-change}} to {{convert|0.7|C-change|F-change}};<ref>{{cite journal |last1=Gillett |first1=Nathan P. |last2=Kirchmeier-Young |first2=Megan |last3=Ribes |first3=Aurélien |last4=Shiogama |first4=Hideo |last5=Hegerl |first5=Gabriele C. |last6=Knutti |first6=Reto |last7=Gastineau |first7=Guillaume |last8=John |first8=Jasmin G. |last9=Li |first9=Lijuan |last10=Nazarenko |first10=Larissa |last11=Rosenbloom |first11=Nan |last12=Seland |first12=Øyvind |last13=Wu |first13=Tongwen |last14=Yukimoto |first14=Seiji |last15=Ziehn |first15=Tilo |title=Constraining human contributions to observed warming since the pre-industrial period |date=18 January 2021 |journal=Nature Climate Change |volume=11 |issue=3 |pages=207–212 |doi=10.1038/s41558-020-00965-9 |bibcode=2021NatCC..11..207G |hdl=20.500.11820/a93e20cb-b6fe-4233-8358-94842d651b2b |url=https://www.research.ed.ac.uk/en/publications/a93e20cb-b6fe-4233-8358-94842d651b2b }}</ref> the IPCC Sixth Assessment Report uses the best estimate of {{convert|0.5|C-change|F-change}},<ref name="IPCC_WGI_SPM">{{cite book |title=Climate Change 2021 – the Physical Science Basis |chapter=Summary for Policymakers |date=2023 |pages=3–32 |doi=10.1017/9781009157896.001 |isbn=978-1-009-15789-6 |author=Intergovernmental Panel on Climate Change }}</ref> with the uncertainty mainly caused by contradictory research on the impacts of aerosols of clouds.<ref name="Andrew">{{cite news |last1=Andrew |first1=Tawana |title=Behind the Forecast: How clouds affect temperatures |url=https://www.wave3.com/2019/09/27/behind-forecast-how-clouds-affect-temperatures/ |access-date=4 January 2023 |work=Science Behind the Forecast |publisher=LOUISVILLE, Ky. (WAVE) |date=27 September 2019 |language=en |archive-date=4 January 2023 |archive-url=https://web.archive.org/web/20230104180929/https://www.wave3.com/2019/09/27/behind-forecast-how-clouds-affect-temperatures/ |url-status=live }}</ref><ref>{{cite journal |last1=McCoy |first1=Daniel T. |last2=Field |first2=Paul |last3=Gordon |first3=Hamish |last4=Elsaesser |first4=Gregory S. |last5=Grosvenor |first5=Daniel P. |title=Untangling causality in midlatitude aerosol–cloud adjustments |journal=Atmospheric Chemistry and Physics |date=6 April 2020 |volume=20 |issue=7 |pages=4085–4103 |doi=10.5194/acp-20-4085-2020 |bibcode=2020ACP....20.4085M |doi-access=free }}</ref><ref>{{cite journal | last1 = Rosenfeld | first1 = Daniel | last2 = Zhu | first2 = Yannian | last3 = Wang | first3 = Minghuai | last4 = Zheng | first4 = Youtong | last5 = Goren | first5 = Tom | last6 = Yu | first6 = Shaocai | year = 2019 | title = Aerosol-driven droplet concentrations dominate coverage and water of oceanic low level clouds | journal = Science | volume = 363| issue = 6427| article-number = eaav0566| doi = 10.1126/science.aav0566 | pmid = 30655446 | doi-access = free }}</ref><ref>{{cite journal | last1=Glassmeier |first1=Franziska |last2=Hoffmann |first2=Fabian |last3=Johnson |first3=Jill S. |last4=Yamaguchi |first4=Takanobu |last5=Carslaw |first5=Ken S. |last6=Feingold |first6=Graham | date=29 January 2021 |title=Aerosol-cloud-climate cooling overestimated by ship-track data | journal=Science |volume =371 |issue=6528 |pages=485–489 |doi=10.1126/science.abd3980 |pmid=33510021 |bibcode=2021Sci...371..485G |doi-access = free }}</ref><ref>{{cite journal |last1=Manshausen |first1=Peter |last2=Watson-Parris |first2=Duncan |last3=Christensen |first3=Matthew W. |last4=Jalkanen |first4=Jukka-Pekka |last5=Stier |first5=Philip Stier |date=7 March 2018 |title=Invisible ship tracks show large cloud sensitivity to aerosol |journal=Nature |volume=610 |issue=7930 |pages=101–106 |doi=10.1038/s41586-022-05122-0 |pmid=36198778 |pmc=9534750 |doi-access=free }}</ref><ref>{{cite journal |last1=Jongebloed |first1=U. A. |last2=Schauer |first2=A. J. |last3=Cole-Dai |first3=J. |last4=Larrick |first4=C. G. |last5=Wood |first5=R. |last6=Fischer |first6=T. P. |last7=Carn |first7=S. A. |last8=Salimi |first8=S. |last9=Edouard |first9=S. R. |last10=Zhai |first10=S. |last11=Geng |first11=L. |last12=Alexander |first12=B. |title=Underestimated Passive Volcanic Sulfur Degassing Implies Overestimated Anthropogenic Aerosol Forcing |date=2 January 2023 |journal=Geophysical Research Letters |volume=50 |issue=1 |article-number=e2022GL102061 |doi=10.1029/2022GL102061 |bibcode=2023GeoRL..5002061J }}</ref> Some are certain that they cool the planet, though, and this led to solar geoengineering proposals known as stratospheric aerosol injection, which seeks to replicate and enhance the cooling from sulfate pollution while minimizing the negative effects on health through deploying in the stratosphere, where only a fraction of the current sulfur pollution would be needed to avoid multiple degrees of warming,<ref name="Visioni2020">{{Cite journal |last1=Visioni |first1=Daniele |last2=Slessarev |first2=Eric |last3=MacMartin |first3=Douglas G |last4=Mahowald |first4=Natalie M |last5=Goodale |first5=Christine L |author-link5=Christine Goodale |last6=Xia |first6=Lili |date=1 September 2020 |title=What goes up must come down: impacts of deposition in a sulfate geoengineering scenario |journal=Environmental Research Letters |volume=15 |issue=9 |page=094063 |bibcode=2020ERL....15i4063V |doi=10.1088/1748-9326/ab94eb |doi-access=free}}</ref> but the assessment of costs and benefits remains incomplete,<ref>{{cite web |url=http://www.met.reading.ac.uk/pg-research/downloads/2009/pgr-charlton.pdf |title=Costs and benefits of geo-engineering in the Stratosphere |author1=Andrew Charlton-Perez |author2=Eleanor Highwood |name-list-style=amp |access-date=17 February 2009 |archive-date=14 January 2017 |archive-url=https://web.archive.org/web/20170114032949/http://www.met.reading.ac.uk/pg-research/downloads/2009/pgr-charlton.pdf }}</ref> even with hundreds of studies into the subject completed by the early 2020s.<ref name="IPCC_WGI_Ch11" />

==== Black carbon ==== Black carbon (BC) or elemental carbon (EC), often called soot, is composed of pure carbon clusters, skeleton balls and fullerenes, and is one of the most important absorbing aerosol species in the atmosphere. It should be distinguished from organic carbon (OC): clustered or aggregated organic molecules on their own or permeating an EC buckyball. Black carbon from fossil fuels is estimated by the IPCC in the Fourth Assessment Report of the IPCC, 4AR, to contribute a global mean radiative forcing of +0.2 W/m2 (was +0.1 W/m2 in the Second Assessment Report of the IPCC, SAR), with a range +0.1 to +0.4 W/m2. A study published in 2013 however, states that "the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W/m2 with 90% uncertainty bounds of (+0.08, +1.27) W/m2" with "total direct forcing by all-black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W/m2".<ref>{{cite journal|last=Bond |first=T. C. |title=Bounding the role of black carbon in the climate system: A scientific assessment |doi=10.1002/jgrd.50171 |volume=118 |issue=11 |journal=Journal of Geophysical Research: Atmospheres |pages=5380–5552|year=2013 |bibcode=2013JGRD..118.5380B|doi-access=free }}</ref>

===Instances=== {{See also|Haze}} thumb|upright=1.5|Solar radiation reduction due to volcanic eruptions Volcanoes are a large natural source of aerosol and have been linked to changes in the Earth's climate often with consequences for the human population. Eruptions linked to changes in climate include the 1600 eruption of Huaynaputina which was linked to the Russian famine of 1601–1603,<ref name="Geology">[http://www.geologytimes.com/Research/1600_Eruption_Caused_Global_Disruption.asp "1600 Eruption Caused Global Disruption"] {{webarchive |url=https://web.archive.org/web/20110215095449/http://www.geologytimes.com/Research/1600_Eruption_Caused_Global_Disruption.asp |date=15 February 2011 }}, ''Geology Times'', 25 April 2008, accessed 13 November 2010</ref><ref>[https://web.archive.org/web/20131219035432/http://www.nbcnews.com/id/24467948/ Andrea Thompson, "Volcano in 1600 caused global disruption"], NBC News, 5 May 2008, accessed 13 November 2010</ref><ref>[http://www.sciencecentric.com/news/article.php?q=08042402 "The 1600 eruption of Huaynaputina in Peru caused global disruption"] {{webarchive |url=https://web.archive.org/web/20100428052829/http://www.sciencecentric.com/news/article.php?q=08042402 |date=28 April 2010 }}, ''Science Centric''</ref> leading to the deaths of two million, and the 1991 eruption of Mount Pinatubo which caused a global cooling of approximately 0.5 °C lasting several years.<ref>{{cite journal |last1=McCormick |first1=M. Patrick |last2=Thomason |first2=Larry W. |last3=Trepte |first3=Charles R. |title=Atmospheric effects of the Mt Pinatubo eruption |journal=Nature |date=February 1995 |volume=373 |issue=6513 |pages=399–404 |doi=10.1038/373399a0 |bibcode=1995Natur.373..399M }}</ref><ref>{{cite journal | vauthors = Stowe LL, Carey RM, Pellegrino PP | year = 1992 | title = Monitoring the Mt. Pinatubo aerosol layer with NOAA/11 AVHRR data | journal = Geophysical Research Letters | volume = 19 | issue = 2 | pages = 159–162 | doi = 10.1029/91GL02958 | bibcode = 1992GeoRL..19..159S }}</ref> Research tracking the effect of light-scattering aerosols in the stratosphere during 2000 and 2010 and comparing its pattern to volcanic activity show a close correlation. Simulations of the effect of anthropogenic particles showed little influence at present levels.<ref name="SN03413">{{cite journal |last1=Perkins |first1=Sid |title=Earth Not So Hot Thanks to Volcanoes |journal=Science |date=4 March 2013 |doi=10.1126/article.26322 |doi-broken-date=30 March 2026 |url=https://www.science.org/content/article/earth-not-so-hot-thanks-volcanoes |access-date=26 January 2022 |archive-date=26 January 2022 |archive-url=https://web.archive.org/web/20220126161436/https://www.science.org/content/article/earth-not-so-hot-thanks-volcanoes |url-status=live }}</ref><ref name="grl.50263">{{cite journal| vauthors = Neely III RR, Toon OB, Solomon S, Vernier JP, Alvarez C, English JM, Rosenlof KH, Mills MJ, Bardeen CG, Daniel JS, Thayer JP |title=Recent anthropogenic increases in SO2 from Asia have minimal impact on stratospheric aerosol|journal=Geophysical Research Letters|volume=40|issue=5|pages=999–1004|doi=10.1002/grl.50263|quote=moderate volcanic eruptions, rather than anthropogenic influences, are the primary source of the observed increases in stratospheric aerosol.|bibcode = 2013GeoRL..40..999N |year=2013|hdl=1721.1/85851 |hdl-access=free}}</ref>

Aerosols are also thought to affect weather and climate on a regional scale. The failure of the Indian monsoon has been linked to the suppression of evaporation of water from the Indian Ocean due to the semi-direct effect of anthropogenic aerosol.<ref name="Chung2006">{{cite journal | vauthors = Chung CE, Ramanathan V | year = 2006 | title = Weakening of North Indian SST Gradients and the Monsoon Rainfall in India and the Sahel | journal = Journal of Climate | volume = 19 | issue = 10| pages = 2036–2045 | doi = 10.1175/JCLI3820.1 |bibcode = 2006JCli...19.2036C }}</ref>

Recent studies of the Sahel drought<ref>{{Cite web|url=http://apollo.eas.gatech.edu/EAS6792/presentations/aerosol_effects.ppt|archive-url=https://web.archive.org/web/20081216221948/http://apollo.eas.gatech.edu/EAS6792/presentations/aerosol_effects.ppt|title=Pollutants and Their Effect on the Water and Radiation Budgets|archive-date=16 December 2008}}</ref> and major increases since 1967 in rainfall in Australia over the Northern Territory, Kimberley, Pilbara and around the Nullarbor Plain have led some scientists to conclude that the aerosol haze over South and East Asia has been steadily shifting tropical rainfall in both hemispheres southward.<ref name="Chung2006" /><ref>{{Cite web|url=http://www.csiro.au/files/files/pbg2.pdf|archive-url=https://web.archive.org/web/20120616044758/http://www.csiro.au/files/files/pbg2.pdf|title=Australian rainfall and Asian aerosols|archive-date=16 June 2012}}</ref>

=== Energy industry knowledge and response to adverse health effects === [[File:2021 Death rates, by energy source.svg|thumb|Deaths caused by accidents and air pollution from fossil fuel use in power plants exceed those caused by production of renewable energy.<ref name="OWID_SafestEnergy_2021">{{cite journal |last1=Ritchie |first1=Hannah |author1-link=Hannah Ritchie |last2=Roser |first2=Max |author2-link=Max Roser |title=What are the safest and cleanest sources of energy? |url=https://ourworldindata.org/safest-sources-of-energy |journal=Our World in Data |archive-url=https://web.archive.org/web/20240115112316/https://ourworldindata.org/safest-sources-of-energy |archive-date=15 January 2024 |date=2021 |url-status=live }} Data sources: Markandya & Wilkinson (2007); UNSCEAR (2008; 2018); Sovacool et al. (2016); IPCC AR5 (2014); Pehl et al. (2017); Ember Energy (2021).</ref>]] Major energy companies understood at least since the 1960s that use of their products causes widespread adverse health effects and death but continued aggressive political lobbying in the United States and elsewhere against clean air regulation and launched major corporate propaganda campaigns to sow doubt regarding the causative link between the burning of fossil fuels and major risks to human life. Internal company memoranda reveal that energy industry scientists and executives knew that air pollutants created by fossil fuels lodge deep in human lung tissue, and cause birth defects in children of oil industry workers. The industry memos acknowledge that automobiles "are by far the greatest sources of air pollution" and also that air pollution causes adverse health effects and lodges toxins, including carcinogens, "deep into the lungs which would otherwise be removed in the throat".<ref name="Milman Oil firms knew">{{cite news |last1=Milman |first1=Oliver |title=Oil firms knew decades ago fossil fuels posed grave health risks, files reveal |url=https://www.theguardian.com/environment/2021/mar/18/oil-industry-fossil-fuels-air-pollution-documents |work=The Guardian |date=18 March 2021 }}</ref>

In response to mounting public concern, the industry eventually created the Global Climate Coalition, an industry lobby group, to derail governments' attempts to regulate air pollution and to create confusion in the public mind about the necessity of such regulation. Similar lobbying and corporate public relations efforts were undertaken by the American Petroleum Institute, a trade association of the oil and gas industry, and the climate change denier private think tank, The Heartland Institute. "The response from fossil-fuel interests has been from the same playbook – first they know, then they scheme, then they deny and then they delay. They've fallen back on delay, subtle forms of propaganda and the undermining of regulation," said Geoffrey Supran, a Harvard University researcher of the history of fossil-fuel companies and climate change. These efforts have been compared, by policy analysts such as Carroll Muffett of the Center for International Environmental Law, to the tobacco industry strategy of lobbying and corporate propaganda campaigns to create doubt regarding the causal connection between cigarette smoking and cancer and to forestall its regulation. In addition, industry-funded advocates, when appointed to senior government positions in the United States, have revised scientific findings showing the deadly effects of air pollution and have rolled back its regulation.<ref name="Milman Oil firms knew" /><ref>{{cite news |last1=Chang |first1=Alvin |last2=Holden |first2=Emily |last3=Milman |first3=Oliver |last4=Yachot |first4=Noa |title=75 ways Trump made America dirtier and the planet warmer |url=https://www.theguardian.com/us-news/ng-interactive/2020/oct/20/trump-us-dirtier-planet-warmer-75-ways |work=The Guardian }}</ref><ref>Union of Concerned Scientists, 27 April 2020 [https://blog.ucsusa.org/elliott-negin/oil-industry-ghostwrites-trumps-deadly-anti-environmental-policies "Oil Industry Ghostwrites Trump's Deadly Anti-Environmental Policies"]</ref>

== Control == {{Update|section|date=April 2026}} === Technologies === [[File:Display VSON WP6910 (air detector) - pm2,5 at Verona (Borgo Milano) Italy - (particulate pollution, polveri sottili) - 2020 01 15 (hour 22.35) OUTdoor & INdoor (HEPA H13) - first publication commons.wikimedia.org.webm|thumb|Fabric filters Hepa effect: without (outdoor) and with filter (indoor)]] {{Main|Dust collector}}

Particulate matter emissions are highly regulated in most industrialized countries. Due to environmental concerns, most industries are required to operate some kind of dust collection system.{{citation needed|date=September 2025}} These systems include inertial collectors (cyclonic separators), fabric filter collectors (baghouses), electrostatic filters used in facemasks,<ref>{{cite web |title=What are PM{{sub|2.5}} filters and why are they effective? |url=https://www.purakamasks.com/pm25-filters |website=Puraka Masks |access-date=4 January 2021 |archive-date=15 November 2020 |archive-url=https://web.archive.org/web/20201115210919/https://www.purakamasks.com/pm25-filters }}</ref> wet scrubbers, and electrostatic precipitators.

Cyclonic separators are useful for removing large, coarse particles and are often employed as a first step or "pre-cleaner" to other more efficient collectors. Well-designed cyclonic separators can be very efficient in removing even fine particulates,<ref>{{cite journal | title=Effect of Inlet Air Volumetric Flow Rate on the Performance of a Two-Stage Cyclone Separator| year=2018| pmc=6644756| last1=Chen| first1=J.| last2=Jiang| first2=Z. A.| last3=Chen| first3=J.| journal=ACS Omega| volume=3| issue=10| pages=13219–13226| doi=10.1021/acsomega.8b02043| doi-access=free| pmid=31458040}}</ref> and may be operated continuously without requiring frequent shutdowns for maintenance.{{citation needed|date=March 2023}}

Fabric filters or baghouses are the most commonly employed in general industry.<ref>{{cite web | url = http://www.baghouse.com/2011/02/01/the-encyclopedia-of-filters-dust-collection-systems/ | title = The Encyclopedia of Dust Collection | author = Dominick DalSanto | date = February 2011 | access-date = 28 March 2012 | archive-date = 6 June 2013 | archive-url = https://web.archive.org/web/20130606044738/http://www.baghouse.com/2011/02/01/the-encyclopedia-of-filters-dust-collection-systems/ | url-status = live }}</ref> They work by forcing dust-laden air through a bag-shaped fabric filter leaving the particulate to collect on the outer surface of the bag and allowing the now clean air to pass through to either be exhausted into the atmosphere or in some cases recirculated into the facility. Common fabrics include polyester and fiberglass and common fabric coatings include PTFE (commonly known as Teflon). The excess dust buildup is then cleaned from the bags and removed from the collector. [[File:Construction dust emitted and rising up during the building rehabilitation of Treasure Garden, Tai Po, Hong Kong.webm|thumb|Substantial amount of construction dust emitted and rising up from a building under rehabilitation on a Saturday afternoon, Treasure Garden, Tai Po, Hong Kong. The rehabilitation scheme is subsidised by the government<ref>{{cite web | url=https://brplatform.org.hk/en/subsidy-and-assistance/integrated-building-rehabilitation-assistance-scheme | title=Integrated Building Rehabilitation Assistance Scheme | access-date=1 March 2023 | archive-date=1 March 2023 | archive-url=https://web.archive.org/web/20230301161844/https://brplatform.org.hk/en/subsidy-and-assistance/integrated-building-rehabilitation-assistance-scheme | url-status=live }}</ref><ref>{{cite web | url=https://brplatform.org.hk/en/subsidy-and-assistance/operation-building-bright-2-0 | title=Operation Building Bright 2.0}}</ref><ref>{{cite web | url=https://www.devb.gov.hk/en/publications_and_press_releases/press/index_id_5376.html | title=DEVB – Press Releases: Operation Building Bright launched (with photos, 2009) | access-date=6 March 2023 | archive-date=6 March 2023 | archive-url=https://web.archive.org/web/20230306104315/https://www.devb.gov.hk/en/publications_and_press_releases/press/index_id_5376.html | url-status=live }}</ref> and contract like this can worth up to a hundred million.<ref>{{cite web | url=https://www.scmp.com/news/hong-kong/law-and-crime/article/3205841/hong-kong-watchdog-arrests-49-suspects-housing-renovation-scam-involving-contracts-worth-hk500 | title=Hong Kong watchdog arrests 49 suspects in housing renovation scam involving contracts worth HK$500 million| date=6 January 2023}}</ref> People are living inside the building throughout the whole period of the renovation work, which usually lasts for over a year,<ref>{{cite web | url=https://www-baby--kingdom-com.translate.goog/forum.php?mod=viewthread&tid=3830940&_x_tr_sl=auto&_x_tr_tl=en | title=大廈外牆維修,你地會搬走嗎? | trans-title=Will you move out because there is building exterior wall repair work? | language=Chinese}}</ref><ref>{{cite web | url=https://www-baby--kingdom-com.translate.goog/forum.php?mod=viewthread&tid=20450481&_x_tr_sl=auto&_x_tr_tl=en | title=買樓難題: 大廈維修, 住得難頂嗎? | trans-title=The problem of buying a house: Is it difficult to live in a building under rehabilitation? | language=Chinese | access-date=1 March 2023 | archive-date=1 March 2023 | archive-url=https://web.archive.org/web/20230301164843/https://www-baby--kingdom-com.translate.goog/forum.php?mod=viewthread&tid=20450481&_x_tr_sl=auto&_x_tr_tl=en | url-status=live }}</ref> and it can be foretold that the residents' exposure to construction dust is even more serious than the occupational exposure of the workers. The possible presence of asbestos and lead paint dust is also worth worrying. This type of rehabilitation works are very common (over 3000 buildings in the first 6 years of the scheme<ref>{{cite web | url= https://www.info.gov.hk/gia/general/201511/20/P201511200594.htm | title=Operation Building Bright improves living environment of residents (with photos/video)}}</ref>), especially in some older districts. With such a large amount of dust emitted, it was obvious that neither water was being sprayed nor dust extraction device was in use, which was a violation of the local law.<ref name="hk law">{{cite web | url = https://www.elegislation.gov.hk/hk/cap311R!en?INDEX_CS=N | title = Hong Kong eLegislation, AIR POLLUTION CONTROL (CONSTRUCTION DUST) REGULATION (Cap.311 section 43) 16 June 1997, L.N. 304 of 1997}}</ref>]]

Wet scrubbers pass the dirty air through a scrubbing solution (usually a mixture of water and other compounds) allowing the particulate to attach to the liquid molecules.<ref>{{cite web | url=https://www.epa.gov/air-emissions-monitoring-knowledge-base/monitoring-control-technique-wet-scrubber-particulate-0 | title=Monitoring by Control Technique – Wet Scrubber For Particulate Matter| date=25 May 2016}}</ref> Electrostatic precipitators electrically charge the dirty air as it passes through. The now charged air then passes through large electrostatic plates which attract the charged particle in the airstream collecting them and leaving the now clean air to be exhausted or recirculated.<ref>{{cite web| url=https://www.epa.gov/air-emissions-monitoring-knowledge-base/monitoring-control-technique-electrostatic-precipitators| title=Monitoring by Control Technique – Electrostatic Precipitators| date=24 May 2016| access-date=24 March 2023| archive-date=24 March 2023| archive-url=https://web.archive.org/web/20230324135235/https://www.epa.gov/air-emissions-monitoring-knowledge-base/monitoring-control-technique-electrostatic-precipitators| url-status=live}}</ref>

=== Measures === For general building construction, some places that have acknowledged the possible health risks of construction dust for decades legally require the relevant contractor to adopt effective dust control measures, although inspections, fines and imprisonments are rare in recent years (for example, two prosecutions with a total fines of {{HKD|6000}} in Hong Kong in the year 2021).<ref>{{cite web | url = https://www.epd.gov.hk/epd/english/laws_regulations/enforcement/resource_enfor3.html | title = Enforcement Activities and Statistics under the Air Pollution Control Ordinance and the Ozone Layer Protection Ordinance 2021 | access-date = 19 January 2023 | archive-date = 19 January 2023 | archive-url = https://web.archive.org/web/20230119044631/https://www.epd.gov.hk/epd/english/laws_regulations/enforcement/resource_enfor3.html | url-status = live }}</ref><ref>{{cite web | url = https://www.info.gov.hk/gia/general/201710/30/P2017103000435.htm | title = Construction contractor fined for carrying out building demolition work in Shek O without appropriate dust control measures | access-date = 19 January 2023 | archive-date = 19 January 2023 | archive-url = https://web.archive.org/web/20230119044625/https://www.info.gov.hk/gia/general/201710/30/P2017103000435.htm | url-status = live }}</ref>

Some of the mandatory dust control measures include<ref>{{cite web | url = https://www.epd.gov.hk/epd/english/greenconstruction/poll_pro/g_building.html | title = Pollution Problems & Practical Solutions | access-date = 19 January 2023 | archive-date = 19 January 2023 | archive-url = https://web.archive.org/web/20230119044633/https://www.epd.gov.hk/epd/english/greenconstruction/poll_pro/g_building.html | url-status = live }}</ref><ref name="hk law" /><ref>{{cite web| last1 = Singh| first1 = Alok| url = https://newindian.in/delhi-govt-to-impose-fines-on-violation-of-anti-dust-norms/| title = Delhi Govt To Impose Fines On Violation Of Anti-Dust Norms| work = THE NEW INDIAN| date = 6 October 2022| access-date = 22 January 2023| archive-date = 22 January 2023| archive-url = https://web.archive.org/web/20230122062159/https://newindian.in/delhi-govt-to-impose-fines-on-violation-of-anti-dust-norms/| url-status = live}}</ref><ref>{{cite web | url=https://law.moj.gov.tw/ENG/LawClass/LawAll.aspx?pcode=O0020058 | title=Management Regulations for Construction Project Air Pollution Control Facilities | access-date=1 March 2023 | archive-date=1 March 2023 | archive-url=https://web.archive.org/web/20230301093237/https://law.moj.gov.tw/ENG/LawClass/LawAll.aspx?pcode=O0020058 | url-status=live }}</ref> load, unload, handle, transfer, store or dispose of cement or dry pulverized fuel ash in a completely enclosed system or facility, and fit any vent or exhaust with an effective fabric filter or equivalent air pollution control system or equipment, enclose the scaffolding of the building with dust screens, use impervious sheeting to enclose both material hoist and debris chute, wet debris with water before it is dumped into a debris chute, have water sprayed on the facade surface before and during grinding work, use grinder equipped with vacuum cleaner for facade grinding work, spray water continuously on the surface for any pneumatic or power-driven drilling, cutting, polishing or other mechanical breaking operation that causes dust emission, unless there is the operation of an effective dust extraction and filtering device, provide hoarding of not less than 2.4 m in height along the whole length of the site boundary, have hard paving on open area and wash every vehicle that leaves the construction sites. Use of automatic sprinkler equipment, automatic carwash equipment and installation of video surveillance system for the pollution control facilities and retain the videos for one month for future inspections.{{citation needed|date=August 2025}}

Besides removing particulates from the source of pollution, they may also be cleaned in the open air (e.g. smog tower, moss wall, and water truck),<ref>{{cite web | url =https://pib.gov.in/PressReleaseIframePage.aspx?PRID=1874314 | title =Revised GRAP to deal with adverse air quality scenario | access-date =22 January 2023 | archive-date =22 January 2023 | archive-url =https://web.archive.org/web/20230122053206/https://pib.gov.in/PressReleaseIframePage.aspx?PRID=1874314 | url-status =live }}</ref> while other control measures employ the use of barriers.<ref>{{cite web | url =https://www.epd.gov.hk/epd/english/news_events/current_issue/a_ts_c4.html | archive-url =https://web.archive.org/web/20030708104652/http://www.epd.gov.hk/epd/english/news_events/current_issue/a_ts_c4.html | archive-date =8 July 2003 | title =Achievements in environmental pollution control on construction activities, 2004 }}</ref>

==Regulation== Most governments have created regulations both for the emissions allowed from certain types of pollution sources (motor vehicles, industrial emissions etc.) and for the ambient concentration of particulates. Particulates are the deadliest form of air pollution due to their ability to penetrate deep into the lungs and blood stream, contributing to premature death from a wide variety of causes including respiratory diseases and cardiovascular diseases.<ref name="Bodor"/><ref name="Kelly"/><ref name="EPA">{{cite web |last1=US EPA |first1=OAR |date=26 April 2016 |title=Health and Environmental Effects of Particulate Matter (PM) |url=https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm |access-date=5 October 2019 |website=US EPA |archive-date=15 December 2019 |archive-url=https://web.archive.org/web/20191215135625/https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm |url-status=live }}</ref>

===Limits / standards set by governments=== {| class="wikitable sortable" ! rowspan="2" | Country/ Region !! colspan="2" | PM{{Sub|2.5}} ({{frac|μg|m{{Sup|3}}}}) !! colspan="2" | PM{{Sub|10}} ({{frac|μg|m{{Sup|3}}}}) !! rowspan="2" | No. of exceedances allowed per year |- ! Yearly avg. ! Daily avg. (24-hour) ! Yearly avg. ! Daily avg (24-hour) |- | '''Australia'''<ref name="AUS2024">{{cite web |last1=Environmental Health Standing Committee (enHealth) of the Australian Health Protection Principal Committee |title=enHealth Guidance for 1-hour PM2.5 and forecast 24-hour PM2.5 air quality categories and public health advice |url=https://www.cdc.gov.au/system/files/2025-10/enhealth-guidance-pm2-5-air-quality-categories-and-public-health-advice.pdf |website=Government of Australia |access-date=22 April 2026|date=2024}}</ref><ref>{{cite web |title=What is the air quality law in Australia? |url=https://www.accessep.com.au/blog/environment-air-pollution-australia-law#:~:text=The%20Australian%20Ambient%20Air%20Quality%20Standards%20set,(hr)%20*%20Carbon%20Monoxide:%209.0%20ppm%20(8hr) |website=Access Environmental Planning |access-date=22 April 2026}}</ref> ||style="text-align:right"| 8 ||style="text-align:right"| 25 ||style="text-align:right"| 25 ||style="text-align:right"| 50 || {{N/a|None}} |- | '''European Union<ref name="IQAir" />''' ||style="text-align:right"| 25 || {{N/a|None}} ||style="text-align:right"| 40 ||style="text-align:right"| 50 || PM{{Sub|2.5}}: None; PM{{Sub|10}}: 35 |- | '''Hong Kong'''<ref>{{cite web| url=https://www.epd.gov.hk/epd/english/environmentinhk/air/air_quality_objectives/air_quality_objectives.html| title=Air Quality Objectives| publisher=Environmental Protection Department, Hong Kong| access-date= 22 April 2026}}</ref><ref>{{cite journal |last1=Wong |first1=Yee Ka |last2=Liu |first2=Kin Man |last3=Yeung |first3=Claisen |last4=Leung |first4=Kenneth K. M. |last5=Yu |first5=Jian Zhen |title=Source apportionment of fine and coarse particulate matter in Hong Kong and its implications to PM10 air quality management |journal=Atmospheric Environment |date=1 March 2026 |volume=368 |article-number=121763 |doi=10.1016/j.atmosenv.2025.121763 |url=https://www.sciencedirect.com/science/article/abs/pii/S1352231025007381 |issn=1352-2310}}</ref> ||style="text-align:right"| 15 ||style="text-align:right"| 37.5 ||style="text-align:right"| 30 ||style="text-align:right"| 75 || PM{{Sub|2.5}}: 18; PM{{Sub|10}}: 9 |- | '''Japan'''<ref>{{cite journal |last1=Shima |first1=M |title=Epidemiological studies on the health impact of air pollution in Japan: their contribution to the improvement of ambient air quality. |journal=Environmental Health and Preventive Medicine |date=2025 |volume=30 |page=30 |article-number=25-00020 |doi=10.1265/ehpm.25-00020 |pmid=40301102 |pmc=12041441 }}</ref><ref>{{cite web |url=http://www.kankyo.metro.tokyo.jp/air/air_pollution/PM2.5/index.html |title=微小粒子状物質(PM{{Sub|2.5}})対策{{pipe}}東京都環境局大気・騒音・振動・悪臭対策 |publisher=Kankyo.metro.tokyo.jp |access-date=1 February 2015 |archive-url=https://web.archive.org/web/20150228230336/http://www.kankyo.metro.tokyo.jp/air/air_pollution/PM2.5/index.html |archive-date=28 February 2015 }}</ref>{{efn|PM{{sub|10}} referred to as Suspended Particulate Matter}}{{efn|PM{{Sub|2.5}} limit since 21 September 2009}} ||style="text-align:right"| 15 ||style="text-align:right"| 35 || {{N/a|None}} ||style="text-align:right"| 100 || {{N/a|None}} |- | '''South Korea'''<ref>{{cite journal |last1=Kang |first1=Soyoung |last2=An |first2=ChanJung |last3=Lee |first3=Dayeong |last4=Jung |first4=Dong-Hee |last5=Jeong |first5=Eunsun |last6=Jeong |first6=Jinju |last7=Song |first7=In-Ho |last8=Shin |first8=Hye Jung |last9=Lee |first9=Seung-Ha |last10=Jung |first10=Hae-Jin |last11=Lim |first11=Yong-Jae |last12=Park |first12=Jung Min |last13=Seong |first13=Jiwon |title=Analysis of air quality based on national monitoring networks in the Republic of Korea, 2023 - annual trends in air quality over two decades in South Korea- |journal=Asian Journal of Atmospheric Environment |date=29 December 2025 |volume=19 |issue=1 |page=28 |doi=10.1007/s44273-025-00073-0 |bibcode=2025AsJAE..19...28K |url=https://link.springer.com/article/10.1007/s44273-025-00073-0 |language=en |issn=2287-1160}}</ref><ref>{{cite web |url=https://www.airkorea.or.kr/ |title=Home |website=airkorea.or.kr}}</ref><ref>{{Cite web | url=http://news.kbs.co.kr/news/view.do?ncd=3621522&ref=A | title=미세먼지 환경기준 선진국 수준 강화...'나쁨' 4배 늘 듯 | access-date=20 March 2018 | archive-date=20 March 2018 | archive-url=https://web.archive.org/web/20180320165848/http://news.kbs.co.kr/news/view.do?ncd=3621522&ref=A | url-status=live }}</ref>{{efn|PM{{sub|10}} limit since 4 December 2006}}{{efn|PM{{Sub|2.5}} limit since 27 March 2018}} ||style="text-align:right"| 15 ||style="text-align:right"| 35 ||style="text-align:right"| 50 ||style="text-align:right"| 100 || {{N/a|None}} |- | '''Taiwan'''<ref>{{cite web |title=Air Quality Standards, Taiwan Air Quality Monitoring Network |url=https://airtw.moenv.gov.tw/ENG/Information/Standard/Rules.aspx |website=Ministry of Environment, Taiwan |date= Sep 18, 2020 |access-date=22 April 2026 |language=en}}</ref><ref>{{cite news |last1=Chen |first1=Chia-yi |last2=Hiciano |first2=Lery |title=Ministry tightens air pollution standards - Taipei Times |url=https://www.taipeitimes.com/News/taiwan/archives/2024/11/22/2003827308 |access-date=22 April 2026 |work=www.taipeitimes.com |date=22 November 2024}}</ref> ||style="text-align:right"| 15 ||style="text-align:right"| 35 ||style="text-align:right"| 50 ||style="text-align:right"| 100 || {{N/a|None}} |- | '''United Kingdom'''<ref>{{cite web | url=https://www.gov.uk/government/statistics/air-quality-statistics/concentrations-of-particulate-matter-pm10-and-pm25 | title= Accredited official statistics: Particulate matter (PM10/PM2.5) |date= 27 June 2025 |website=GOV.UK }}</ref>|| style="text-align:right" | 20||style="text-align:right"| ||style="text-align:right"| 40 ||style="text-align:right"| 50 ||style="text-align:center"| 35 |- | '''United States'''<ref name="OHIO2026">{{cite web |title=National Ambient Air Quality Standards (NAAQS) - Attainment Status |url=https://epa.ohio.gov/divisions-and-offices/air-pollution-control/guides-and-manuals/national-ambient-air-quality-standards-naaqs-attainment-status |website=epa.ohio.gov |access-date=23 April 2026 |language=en}}</ref><ref name=":0">{{cite web |last1=[ATSDR] Agency for Toxic Substances and Disease Registry |title=Guidance for Inhalation Exposures to Particulate Matter |date=June 2024 |url=https://www.atsdr.cdc.gov/pha-guidance/resources/ATSDR-Particulate-Matter-Guidance-508.pdf |website=U.S. Department of Health and Human Services, Public Health Service |location =Atlanta, GA |access-date=22 April 2026}}</ref>|| style="text-align:right" | 9{{efn|annual limit since 2024}} ||style="text-align:right"| 35{{efn|daily limit since 2007}} || {{N/a|None{{efn|annual limit removed in 2006}}}} ||style="text-align:right"| 150{{efn|daily limit since 1987<ref>{{cite web |url=http://www.epa.gov/airtrends/aqtrnd95/pm10.html |title=Environmental Protection Agency – Particulate Matter (PM-10) |publisher=Epa.gov |date=28 June 2006 |access-date=1 February 2015 |archive-date=1 September 2012 |archive-url=https://web.archive.org/web/20120901140447/http://www.epa.gov/airtrends/aqtrnd95/pm10.html }}</ref>}} || PM{{Sub|2.5}}: Not applicable;{{efn|3-year average of annual 98th percentile}} PM{{Sub|10}}: 1 |- | '''World Health Organization'''<ref name="who-9789240034228"/>|| style="text-align:right" | 5 ||style="text-align:right"| 15 ||style="text-align:right"| 15 ||style="text-align:right"| 45 ||style="text-align:center"| 3–4 |}

===Canada===

The Canadian Ambient Air Quality Standard (CAAQS) for particulate matter is set nationally by the federal-provincial Canadian Council of Ministers of the Environment (CCME).<ref name="Canada"/> Jurisdictions (provinces and territories) may set more stringent standards. <ref name="BC"/>

As of 2020, the CCME standard for PM{{sub|2.5}} is 27 μg/m{{sup|3}} (calculated using the 3-year average of the annual 98th percentile of the daily 24-hr average concentrations) and 8.8 μg/m3 (3-year average of annual mean). Standards for ozone, nitrogen dioxide, and sulphur dioxide are also set.<ref name="Canada">{{cite web |last1=Canada |first1=Environment and Climate Change |title=Population exposure to outdoor air pollutants |url=https://www.canada.ca/en/environment-climate-change/services/environmental-indicators/population-exposure-outdoor-air-pollutants.html |website=Government of Canada |access-date=21 April 2026 |date=15 March 2021}}</ref>

In 2025, more stringent national standards were endorsed to take effect as of 2030. The 2030 CAAQS for PM{{sub|2.5}} are 23 μg/m{{sup|3}} (calculated using the 3-year average of the annual 98th percentile of the daily 24-hr average concentrations) and 8.0 μg/m3 (3-year average of annual mean).<ref name="BC">{{cite web |last1=Strategy |first1=Ministry of Environment and Climate Change |title=Provincial air quality objectives for PM2.5 - Province of British Columbia |url=https://www2.gov.bc.ca/gov/content/environment/air-land-water/air/air-quality-management/regulatory-framework/objectives-standards/pm2-5 |website=Government of British Columbia |access-date=21 April 2026}}</ref>

===China=== Air pollution in China is a long-standing public health issue. In 2013, China introduced an Air Pollution Prevention and Control Action Plan to reduce pollution levels, which has led to improvements in air quality.<ref name="Yang2026">{{cite journal |last1=Yang |first1=Yang |last2=Yang |first2=Hongyan |last3=Ye |first3=Jing |last4=Yang |first4=Guanglei |last5=Deng |first5=Zhiyu |last6=Li |first6=Dequan |title=From lenient to stringent: Environmental policy target adjustment and the decline in mortality |journal=Economic Analysis and Policy |date=1 June 2026 |volume=91 |pages=647–667 |doi=10.1016/j.eap.2026.03.039 |issn=0313-5926}}</ref>

On February 24, 2026, China's Ministry of Ecology and Environment further updated its ambient air quality standards, to be implemented in two phases. During a transitional phase, from March 1, 2026 through December 31, 2030, the annual PM{{sub|2.5}} limit will be 30 μg/m{{sup|3}} and the PM{{sub|10}} limit will be 60 μg/m{{sup|3}}.<ref name="China2026"/>

As of January 1, 2031, China's annual average limit for PM{{sub|2.5}} will become 25 μg/m{{sup|3}} and the annual average limit for PM{{sub|10}} will be reduced to 50 μg/m{{sup|3}}. In addition, the annual limits for sulfur dioxide will drop from 60 to 20 μg/m{{sup|3}}, and for nitrogen dioxide will drop from 40 to 30 μg/m{{sup|3}}.<ref name="China2026">{{cite news |last1=HOU |first1=LIQIANG |title=New air quality norms to aid health, cut emissions |url=https://www.chinadaily.com.cn/a/202602/26/WS699f9c9da310d6866eb3a4b0.html |access-date=22 April 2026 |work=China Daily |date=February 26, 2026}}</ref><ref name="Day">{{cite news |last1=Day |first1=Paul |title=China tightens ambient air quality standards |url=https://airqualitynews.com/headlines/china-tightens-ambient-air-quality-standards/ |access-date=22 April 2026 |work=AirQualityNews |date=26 February 2026 |language=en}}</ref>

===European Union=== The European Union has established air quality legislation through the passage of Ambient Air Quality Directives (AAQD), National Emission Ceilings Directives (NECD), and various source-specific directives. First introduced in 1980, AAQDs have defined limits for sulfur dioxide, particulate matter, lead, nitrogen dioxide, PM{{sub|10}} and PM{{sub|2.5}}.<ref name="Malmqvist"/> National Emission Ceilings Directives (NECD) and European emission standards for vehicles also limit sulphur dioxide (SO2), nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOCs) and ammonia (NH3) as well as particulate matter in air.<ref name="Malmqvist"/><ref name="status2022">{{cite web |title=National Emission reduction Commitments Directive reporting status 2022 |url=https://www.eea.europa.eu/en/analysis/publications/national-emission-reduction-commitments-directive-reporting-status-2022 |website=www.eea.europa.eu |access-date=21 April 2026 |language=en |date=11 July 2022}}</ref>

{{Clear}} {| class="wikitable" |- ! European Air Quality Index !! Good !! Fair !! Moderate !! Poor !! Very poor !! Extremely poor |- | Particles less than 2.5μm (PM{{sub|2,5}}) || 0–10 μg/m{{sup|3}} || 10–20 μg/m{{sup|3}} || 20–25 μg/m{{sup|3}} || 25–50 μg/m{{sup|3}} || 50–75 μg/m{{sup|3}} || 75–800 μg/m{{sup|3}} |- | Particles less than 10μm (PM{{sub|10}}) || 0–20 μg/m{{sup|3}} || 20–40 μg/m{{sup|3}} || 40–50 μg/m{{sup|3}} || 50–100 μg/m{{sup|3}} || 100–150 μg/m{{sup|3}} || 150–1200 μg/m{{sup|3}} |}

Changes to EU standards have been passed and will be phased in beginning in 2026. The Euro 7 vehicle emissions standards will be phased in beginning 29 November 2026. They will cover petrol, diesel, and electric vehicles. Euro 7 will be the first standard to regulate sources of pollution such as dust from tires and brakes, not just exhaust fumes.<ref name="Menzies">{{cite news |last1=Menzies |first1=Liam |title=What You Need to Know About the Euro 7 Emissions Standards |url=https://www.blackcircles.com/news/euro-7-emissions-standards |access-date=21 April 2026 |work=Blackcircles |date=March 3, 2026 |language=en}}</ref><ref name="Malmqvist">{{cite journal |last1=Malmqvist |first1=E |last2=Kelly |first2=F |last3=Brunekreef |first3=B |title=Europe Is Tightening Its Air Quality Standards: When Will Britain Follow Suit? |journal=Annals of the American Thoracic Society |date=October 2025 |volume=22 |issue=10 |pages=1460–1462 |doi=10.1513/AnnalsATS.202502-244VP |pmid=40607959 |pmc=12499880 }}</ref><ref name="Dornoff">{{cite web |last1=Dornoff |first1=Jan |last2=Rodríguez |first2=Felipe |title=Euro 7: The new emission standard for light- and heavy-duty vehicles in the European Union |url=https://theicct.org/wp-content/uploads/2024/03/ID-116-%E2%80%93-Euro-7-standard_final_v2.pdf |website=International Council on Clean Transportation |access-date=21 April 2026|date=2024}}</ref>

As of December 10, 2024, the European Union updated its Ambient Air Quality Directive (AAQD), giving EU member states until December 11, 2026 to implement the updated directive in their national laws and achieve interim targets, with stricter values to be attained by January 1, 2030.<ref name="IQAir">{{cite news |title=EU tightens air pollution standards: What it means for public health |url=https://www.iqair.com/newsroom/eu-tightens-air-pollution-standards |access-date=21 April 2026 |work=IQAir |date=30 Mar 2026}}</ref>

{{Clear}} {| class="wikitable" |- ! European Air Quality Index !! Target by December 11, 2026<ref name="IQAir"/> !! Target by January 1, 2030<ref name="IQAir"/> |- | Particles less than 2.5μm (PM{{sub|2.5}}) Annual || 25 μg/m{{sup|3}} || 10 μg/m{{sup|3}} |- | Particles less than 10μm (PM{{sub|10}}) Annual || 40 μg/m{{sup|3}} || 20 μg/m{{sup|3}} |- | Particles less than 10μm (PM{{sub|10}}) Daily limit and allowed days || 50 μg/m{{sup|3}} ≤ 35 days/year || 45 μg/m{{sup|3}} ≤ 18 days/year |- | NO{{sub|2}} Annual || 40 μg/m{{sup|3}} || 20 μg/m{{sup|3}}

===United Kingdom=== The Clean Air Act of 1956 was a pivotal act of the Parliament of the United Kingdom for UK pollution control policies. Enacted in response to 1952's Great Smog of London, it allowed local authorities to declare smoke control areas and laid the foundation for future pollution control measures.<ref name="London">{{cite web | url=https://www.london.gov.uk/programmes-strategies/environment-and-climate-change/environment-and-climate-change-publications/70-years-great-london-smog | author= Mayor of London & London Assembly |title=70 years since the great London smog: 1952, air quality in a modern context| date=5 December 2022|access-date=23 August 2025|website=Environment and Climate Change|last=|type=Government Report|publisher=Greater London Authority}}</ref><ref name="brimblecombe" />

To mitigate the problem of wood burning, starting from May 2021, traditional house coal (bituminous coal) and wet wood, two of the most polluting fuels, can no longer be sold.<ref>{{cite web |title=The Air Quality (Domestic Solid Fuels Standards) (England) Regulations 2020 |url=https://www.legislation.gov.uk/uksi/2020/1095/contents/made |website=www.legislation.gov.uk |access-date=16 April 2026 |language=en}}</ref> Wood sold in volumes of less than 2m3 must be certified as 'Ready to Burn', which means it has a moisture content of 20% or less. Manufactured solid fuels must also be certified as 'Ready to Burn' to ensure they meet sulfur and smoke emission limits.<ref>{{cite web | url=https://uk-air.defra.gov.uk/library/burnbetter/ | title=Burn Better, Breathe Better: Reduce the negative impact your stove or open fire can have on your health |website=UK Air| access-date=16 April 2026 | archive-date=5 March 2023 | archive-url=https://web.archive.org/web/20230305154807/https://uk-air.defra.gov.uk/library/burnbetter/ | url-status=live }}</ref> Starting from January 2022, all new wood burning stoves must meet new EcoDesign standards (Ecodesign stoves produce 450 times more toxic air pollution than gas central heating. Older stoves, which are now banned from sale, produce 3,700 times more).<ref>{{cite web | url=https://www.london.gov.uk/programmes-and-strategies/environment-and-climate-change/pollution-and-air-quality/guidance-wood-burning-london | author= Mayor of London & London Assembly | title=Guidance for wood burning in London |website=Environment and Climate Change|last=|publisher=Greater London Authority}}</ref>

As of 2023, the amount of smoke that burners in "smoke control areas" – most England's towns and cities – can emit per hour was reduced from 5g to 3g. Violations can result in an on-the-spot fine of up to £300 and a possible criminal record.<ref>{{cite web| url=https://www.independent.co.uk/climate-change/news/log-burners-rules-wood-stoves-b2276589.html?amp| author-first=Joe |author-last=Sommerlad |title=Log burners: What are the new rules and are they going to be banned?| website=Independent.co.uk| date=6 February 2023| access-date=5 March 2023| archive-date=5 March 2023| archive-url=https://web.archive.org/web/20230305154805/https://www.independent.co.uk/climate-change/news/log-burners-rules-wood-stoves-b2276589.html?amp| url-status=live}}</ref>

===United States=== thumb|400px| The number of days each year that ozone and PM2.5 exceeded US standards, 2000-2024

thumb|upright=1.55| PM{{sub|2.5}} air quality trends in the United States, 2000-2017. Blue area shows the range of the middle 80% of monitoring sites.<ref>{{Cite web |url=https://www.epa.gov/air-trends/air-quality-trends-how-interpret-graphs |title=Air Quality Trends – How to Interpret the Graphs |date=April 1, 2026 |access-date=15 May 2024 |archive-date=15 May 2024 |archive-url=https://web.archive.org/web/20240515204010/https://www.epa.gov/air-trends/air-quality-trends-how-interpret-graphs |url-status=live }}</ref> As required by the Clean Air Act, the United States Environmental Protection Agency (EPA) sets National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to public health and the environment. The six criteria air pollutants are particulate matter (PM{{sub|10}} and PM{{sub|2.5}}), carbon monoxide, lead, ozone, nitrogen dioxide, and sulfur dioxide. Target levels are designated as either primary (protecting public health) or secondary (protecting "public welfare" due to harms against animals, crops, vegetation, buildings and decreased visibility). NAAQS for PM{{sub|10}} and PM{{sub|2.5}} are: <ref name="OHIO2026"/>

{| class="wikitable" |- ! Pollutant !! Type !! Standard!! Averaging Time!! Exceedance Criteria !! Regulatory Citation |- | rowspan="3" | Fine particulate matter (PM2.5) | Primary | 9.0 μg/m3 (12 μg/m3 prior to May 6, 2024)<ref>{{cite web |url=https://www.federalregister.gov/documents/2024/03/06/2024-02637/reconsideration-of-the-national-ambient-air-quality-standards-for-particulate-matter |title=Reconsideration of the National Ambient Air Quality Standards for Particulate Matter |date=6 March 2024 |author=Environmental Protection Agency}}</ref> | annual | Annual mean, averaged over 3 years | {{USCFR|40|50|18|a}} |- | Secondary | 15 μg/m3 | annual | Annual mean, averaged over 3 years | {{USCFR|40|50|7|a}} |- | Primary and Secondary | 35 μg/m3 | 24-hour | 98th percentile, averaged over 3 years | {{USCFR|40|50|18|a}}

|- | Particulate matter (PM10) | Primary and Secondary | 150 μg/m3 | 24-hour | Not to be exceeded more than once per year on average over 3 years | {{USCFR|40|50|6|a}}

In addition, states, local agencies, and tribal governments can set stricter air quality standards. They are required to develop NAAQS-compliant plans to ensure that national standards are also being met.<ref>{{cite web |last1=US EPA |first1=OFA |title=Regulatory and Guidance Information by Topic: Air |url=https://www.epa.gov/regulatory-information-topic/regulatory-and-guidance-information-topic-air |website=www.epa.gov |access-date=23 April 2026 |language=en |date=22 February 2013}}</ref> {{clear}}

====California==== The California Environmental Protection Agency and its department, the California Air Resources Board (CARB) have repeatedly taken action to set stricter ambient air quality standards. In some cases, such as PM{{Sub|10}}, California ambient air quality standards (CAAQS) are more stringent than national standards.<ref>{{cite web |title=History of California's Ambient Air Quality Standards {{!}} California Air Resources Board |url=https://ww2.arb.ca.gov/resources/documents/history-californias-ambient-air-quality-standards |website=ww2.arb.ca.gov |access-date=23 April 2026}}</ref><ref name="CAAQS">{{cite web |title=Inhalable Particulate Matter and Health (PM2.5 and PM10) {{!}} California Air Resources Board |url=https://ww2.arb.ca.gov/resources/inhalable-particulate-matter-and-health |website=ww2.arb.ca.gov}}</ref><ref name="baaqmd">{{cite web |title=Air Quality Standards and Attainment Status |url=https://www.baaqmd.gov/about-air-quality/research-and-data/air-quality-standards-and-attainment-status |website=Bay Area Air District |access-date=23 April 2026}}</ref> Regional initiatives such as the 2006 California Goods Movement Plan have been linked to improvements in air quality and health outcomes.<ref>{{cite journal |last1=Meng |first1=YY |last2=Su |first2=JG |last3=Chen |first3=X |last4=Molitor |first4=J |last5=Yue |first5=D |last6=Jerrett |first6=M |title=Improvements in Air Quality and Health Outcomes Among California Medicaid Enrollees Due to Goods Movement Actions. |journal=Research Report (Health Effects Institute) |date=May 2021 |volume=2021 |issue=205 |pages=1–61 |pmid=35869754 |pmc=9314313 }}</ref>

{| class="wikitable" ! rowspan="2" | Country/ Region !! colspan="2" | PM{{Sub|2.5}} !! colspan="2" | PM{{Sub|10}} |- ! Yearly avg. ! Daily avg. (24-hour) ! Yearly avg. ! Daily avg (24-hour) |- | '''California Ambient Air Quality Standards'''<ref name="CAAQS"/><ref name="baaqmd"/> | 12 μg/m3 | NA | 20 μg/m3 | 50 μg/m3 |}

====Colorado==== Colorado generally follows National Ambient Air Quality Standards (NAAQS) for criteria air pollutants. Its State Implementation Plan (SIP) outlines the steps to be taken to enforce the NAAQS. Counties that exceed thresholds for criteria air pollutants are designated as "nonattainment areas". The Air Quality Control Commission (AQCC), appointed by the Governor and confirmed by the Senate, oversees Colorado's air quality program. The Air Pollution Control Division (APCD) of the Colorado Department of Public Health and Environment (CDPHE) monitors the air quality index (AQI) and reports daily air quality and health alerts. The Regional Air Quality Council (RAQC) has been the lead air quality planning agency for the metro Denver area since 1989.<ref name="Mem2025">{{cite web |title=Memorandum, September 12, 2025: Air Pollution Regulation in Colorado |url=https://content.leg.colorado.gov/sites/default/files/r25-744_air_pollution_regulation-accessible.pdf |website=Legislative Council Staff Nonpartisan Services for Colorado's Legislature |access-date=23 April 2026|date=September 12, 2025}}</ref>

The metro area of Denver, Colorado's capital, is of particular concern due to ozone and particulate pollution from industry, vehicles, power plants, refineries, and airports.<ref name="Mem2025"/> Denver's location at the foot of the Rocky Mountains and local meteorological conditions tend to physically collect and hold pollutants. In the winter, cold air often settles in the valley with warmer air above it. Such temperature inversions trap particulate matter near the ground.<ref name="Hastings">{{cite news |last1=Hastings |first1=Matthew |title=Mile High Smog: Understanding Colorado's Air Pollution |url=https://news.cuanschutz.edu/news-stories/mile-high-smog-understanding-colorados-air-pollution#:~:text=Air%20pollution%20in%20Colorado%20is%20caused%20by,sources**%20*%20**Leaf%20blowers%20and%20lawn%20mowers** |access-date=23 April 2026 |work=University of Colorado Anschutz News |date=July 30, 2024 |language=en}}</ref> Hot and dry conditions during the summer time put the area at risk for forest fires.<ref>{{cite journal |last1=Geng |first1=G |last2=Murray |first2=NL |last3=Tong |first3=D |last4=Fu |first4=JS |last5=Hu |first5=X |last6=Lee |first6=P |last7=Meng |first7=X |last8=Chang |first8=HH |last9=Liu |first9=Y |title=Satellite-Based Daily PM(2.5) Estimates During Fire Seasons in Colorado. |journal=Journal of Geophysical Research. Atmospheres : JGR |date=16 August 2018 |volume=123 |issue=15 |pages=8159–8171 |doi=10.1029/2018JD028573 |pmid=31289705 |pmc=6615892 }}</ref>

As of April 2026, the Colorado Air Quality Control Commission adopted new emission standards for five toxic air contaminants in addition to those covered by the NAAQS: Hydrogen sulfide, Benzene, Formaldehyde, Ethylene oxide, and Hexavalent chromium compounds.<ref>{{cite news |title=Colorado approves measures to control toxic air pollution from key industries |url=https://cdphe.colorado.gov/press-release/colorado-approves-measures-to-control-toxic-air-pollution-from-key-industries |access-date=23 April 2026 |work=Colorado Department of Public Health and Environment |date=April 17, 2026}}</ref><ref name="Sealover">{{cite news |last1=Sealover |first1=Ed |title=Colorado board adopts precedent-setting emissions controls for toxic air contaminants |url=https://tsscolorado.com/colorado-board-adopts-precedent-setting-emissions-controls-for-toxic-air-contaminants/ |access-date=23 April 2026 |work=The Sum and Substance |date=20 April 2026}}</ref><ref name="Jacobs">{{cite news |last1=Jacobs |first1=Jesse |title=Colorado Tightens Restrictions on Toxic Air Contaminants - |url=https://eponline.com/articles/2026/04/20/colorado-tightens-restrictions-on-toxic-air-contaminants.aspx?admgarea=News |access-date=23 April 2026 |work=Environmental Protection |date=April 20, 2026}}</ref>

== Particulate matter worldwide == === PM{{sub|2.5}} by city === thumb|upright=1.65|Difference between levels of PM{{sub|2.5}} in the air in 2019 and 2022 among 70 capital cities<ref name=housefresh>{{cite web| url=https://housefresh.com/the-cities-where-air-pollution-has-increased-and-decreased-the-most-since-2019/| title=The Cities Where Air Pollution Has Increased and Decreased the Most since 2019| date=20 February 2023| access-date=28 March 2023| archive-date=28 March 2023| archive-url=https://web.archive.org/web/20230328135328/https://housefresh.com/the-cities-where-air-pollution-has-increased-and-decreased-the-most-since-2019/| url-status=live}}</ref> To analyse the air pollution trend, 480 cities around the world (Ukraine excluded) was mapped by air experts<ref name=housefresh /> to calculate the average PM{{sub|2.5}} level of the first nine months of 2019 against that of 2022.<ref>{{cite web| last1=Madden| first1=Duncan| url=https://www.forbes.com/sites/duncanmadden/2023/03/17/mapped-new-survey-shows-air-pollution-changes-in-cities-around-the-world/| title=Mapped: New Survey Shows Air Pollution Changes In Cities Around The World| website=Forbes| access-date=28 March 2023| archive-date=28 March 2023| archive-url=https://web.archive.org/web/20230328161701/https://www.forbes.com/sites/duncanmadden/2023/03/17/mapped-new-survey-shows-air-pollution-changes-in-cities-around-the-world/| url-status=live}}</ref> Average levels of PM{{sub|2.5}} were measured using aqicn.org's World Air Quality Index data, and a formula developed by AirNow was used to convert the PM{{sub|2.5}} figure into micrograms per cubic meter of air ({{frac|μg|m{{Sup|3}}}}) values.

Among the 70 capital cities investigated, Baghdad, Iraq is the worst performing one, with PM{{sub|2.5}} levels going up {{val|+31.6|ul=ug|upl=m3}}. Ulan Bator (Ulaanbaatar), the capital city of Mongolia, is performing the best, with PM{{sub|2.5}} levels dropping by {{val|-23.4|u=ug|up=m3}}. Previously it was as one of the most polluted capital cities in the world. An air quality improvement plan in 2017 appears to be showing positive results.

Out of the 480 cities, Dammam in Saudi Arabia is performing the worst with PM{{sub|2.5}} levels going up {{val|+111.1|u=ug|up=m3}}. The city is a significant center for the Saudi oil industry and home to both the largest airport in the world and the largest port in the Persian Gulf. It is currently the most polluted city surveyed.

In Europe, the worst performing cities are located in Spain. They are Salamanca and Palma, with PM{{sub|2.5}} levels increase by {{val|+5.1|u=ug|up=m3}} and {{val|+3.7|u=ug|up=m3}} respectively. The best performing city is Skopje, the capital city of North Macedonia, with PM{{sub|2.5}} levels dropping by {{val|-12.4|u=ug|up=m3}}. It was once the most polluted capital city in Europe and still has a long way to go to achieve clean air.

In the U.S., Salt Lake City, Utah and Miami, Florida are the two cities with the highest PM{{sub|2.5}} level increases ({{val|+1.8|u=ug|up=m3}}). Salt Lake City suffers from a weather event known as 'inversion'. Located in a valley, cooler, polluted air is trapped close to ground level under the warmer air above when inversion occurs. On the other hand, Omaha, Nebraska is performing the best and has a decrease of {{val|-1.1|u=ug|up=m3}} in PM{{sub|2.5}} levels.

The cleanest city in this report is Zürich, Switzerland with PM{{sub|2.5}} levels of just '''{{val|0.5|u=ug|up=m3}}''', placed first in both 2019 and 2022. The second cleanest city is Perth, with {{val|1.7|u=ug|up=m3}} and PM{{sub|2.5}} levels dropping by {{val|-6.2|u=ug|up=m3}} since 2019. Of the top ten cleanest cities, five are from Australia. They are Hobart, Wollongong, Launceston, Sydney and Perth. Honolulu is the only U.S. city in the top ten list, ranking tenth with levels of {{val|4|u=ug|up=m3}}, with a tiny increase since 2019.

Almost all of the top ten most polluted cities are in the Middle East and Asia. The worst is Dammam in Saudi Arabia with a PM{{sub|2.5}} level of '''{{val|155|u=ug|up=m3}}'''. Lahore in Pakistan is the second worst with {{val|98.1|u=ug|up=m3}}. The third is Dubai, home to the world's tallest building. In the bottom ten are three cities from India, Muzaffarnagar, Delhi and New Delhi. Here is a list of the '''30 most polluted cities by PM{{sub|2.5}}''', Jan to Sep 2022:<ref name=housefresh /> {| class="wikitable sortable collapsible" style="margin-left: auto; margin-right: auto; border: none;" ! rowspan="2" | City !! rowspan="2" | Country / Region !! colspan="2" | Months average PM{{sub|2.5}} ({{frac|μg|m{{Sup|3}}}}) |- ! 2022 ! 2019 |- | Dammam || {{Flag| Saudi Arabia}} || 155 || 43.9 |- | Lahore || {{Flag| Pakistan}} || 98.1 || 64.6 |- | Dubai || {{Flag| United Arab Emirates}} || 97.7 || 47.5 |- | Baghdad || {{Flag| Iraq}} || 60.5 || 29 |- | Dhaka || {{Flag| Bangladesh}} || 55.3 || 48.7 |- | Muzaffarnagar || {{Flag| India}} || 53.9 || 60.5 |- | Delhi || {{Flag| India}} || 51.6 || 59.8 |- | Oaxaca || {{Flag| Mexico}} || 51.1 || 13.5 |- | New Delhi || {{Flag| India}} || 50.1 || 54.2 |- | Manama || {{Flag| Bahrain}} || 48 || 43.4 |- | Patna || {{Flag| India}} || 47.9 || 53.5 |- | Peshawar || {{Flag| Pakistan}} || 47 || 46.7 |- | Ghāziābād || {{Flag| India}} || 46.6 || 56.9 |- | Lucknow || {{Flag| India}} || 46.4 || 54.1 |- | Hawalli || {{Flag| Kuwait}} || 46.2 || 40.4 |- | Hapur || {{Flag| India}} || 45.7 || 53.3 |- | Chandigarh || {{Flag| India}} || 44.9 || 39.7 |- | Jaipur || {{Flag| India}} || 43.5 || 40.6 |- | Kampala || {{Flag| Uganda}} || 42.9 || 48.3 |- | Khorramshahr || {{Flag| Iran}} || 42 || 30 |- | Pokhara || {{Flag| Nepal}} || 41.8 || 18.2 |- | Abu Dhabi || {{Flag| United Arab Emirates}} || 40.2 || 44.7 |- | Xi'an || {{Flag| China}} || 36.6 || 40 |- | Xuchang || {{Flag| China}} || 36.4 || 41.4 |- | Xinxiang || {{Flag| China}} || 36.3 || 46.4 |- | Anyang || {{Flag| China}} || 36.1 || 45.9 |- | Shijiazhuang || {{Flag| China}} || 36 || 44.9 |- | Taiyuan || {{Flag| China}} || 35.9 || 39.2 |- | East London || {{Flag| South Africa}} || 35.9 || 7.1 |- | Gandhinagar {{ns|16}} || {{Flag| India}} {{ns|26}} || 35.5 || 42.9 |- |} There are limits to the above survey. For example, not every city in the world is covered, and that the number of monitoring stations for each city would not be the same. The data is for reference only.

===Australia=== PM10 pollution in coal mining areas in Australia such as the Latrobe Valley in Victoria and the Hunter Region in New South Wales significantly increased during 2004 to 2014, with the rate of increase rising each year from 2010 to 2014.<ref name=Guardian4115>{{cite news|author1=Oliver Milman|title=Call for action on pollution as emissions linked to respiratory illnesses double|url=https://www.theguardian.com/environment/2015/apr/02/call-for-action-on-pollution-as-emissions-linked-to-respiratory-illnesses-double|access-date=3 April 2015|work=The Guardian|date=1 April 2015|quote=emissions of a key pollutant linked to respiratory illness have doubled over the past five years}}</ref> According to National Pollutant Inventory data, PM10, PM2.5, metals and nitrogen oxide emissions increased alongside rising coal production between 2008 and 2018. Coal mines accounted for 42.1% of national PM10 emissions, of which 19.5% was PM2.5.<ref name="Hendryx">{{cite journal |last1=Hendryx |first1=M |last2=Islam |first2=MS |last3=Dong |first3=GH |last4=Paul |first4=G |title=Air Pollution Emissions 2008-2018 from Australian Coal Mining: Implications for Public and Occupational Health. |journal=International Journal of Environmental Research and Public Health |date=29 February 2020 |volume=17 |issue=5 |page=1570 |doi=10.3390/ijerph17051570 |doi-access=free |pmid=32121344 |pmc=7084742 |bibcode=2020IJERP..17.1570H }}</ref>

Australia is also being affected by severe wildfires. The fire season of 2019–20 was known in Australia as Black Summer. Massive wildfires burned over 186,000 square kilometers of land, producing plumes of smoke and particulate matter. This increased concentrations of ice crystals, resulting in as much as 270% more lightning activity and 240% more rainfall in lightning storms over the Tasman Sea.<ref>{{cite news |last1=Ogasa |first1=Nikk |title=Air pollution helps wildfires create their own lightning: Finding could have wide-ranging ramifications for weather patterns |journal=Science |department=Environment |date=25 May 2021 |doi=10.1126/science.abj6782 |doi-access=free}}</ref> Mineral dust and smoke particles from the fire emissions altered particulate composition on the surface of the ocean.<ref>{{cite journal |last1=Li |first1=Mengyu |last2=Shen |first2=Fang |last3=Sun |first3=Xuerong |title=2019‒2020 Australian bushfire air particulate pollution and impact on the South Pacific Ocean |journal=Scientific Reports |date=10 June 2021 |volume=11 |issue=1 |page=12288 |doi=10.1038/s41598-021-91547-y |pmid=34112861 |pmc=8193010 |bibcode=2021NatSR..1112288L |language=en |issn=2045-2322}}</ref>

===China=== {{See also|Pollution in China#Particulates}} Air pollution in China has long been a public health issue, estimated to contribute to 1.67 million premature deaths nationally in 2020. Exposure to particulate matter is the nation's fourth leading risk factor for mortality.<ref name="Wang2026">{{cite journal |last1=Wang |first1=S |last2=Xu |first2=Z |last3=Di Tanna |first3=GL |last4=Jiang |first4=Y |last5=Chen |first5=M |last6=Downey |first6=L |last7=Jan |first7=S |last8=Si |first8=L |title=Projected Health and Economic Benefits of Air Quality Targets in China: Modeling Study. |journal=JMIR Public Health and Surveillance |date=1 April 2026 |volume=12 |pages=e84809 |article-number=v12i8e84809 |doi=10.2196/84809 |doi-access=free |pmid=41921085 |pmc=13043006 }}</ref> PM2.5 has been identified as the primary contributor to atmospheric particulate pollution in China.<ref name="pmid29498704">{{cite journal |vauthors=Lin Y, Zou J, Yang W, Li CQ |title=A Review of Recent Advances in Research on PM2.5in China |journal=Int J Environ Res Public Health |volume=15 |issue=3 |date=March 2018 |page=438 |pmid=29498704 |pmc=5876983 |doi=10.3390/ijerph15030438 |doi-access=free |url=}}</ref>

Pollution levels in Chinese cities were extreme between 2010 and 2014. In 2011, in Beijing, a "Crazy Bad" air quality index (AQI) was reported that exceeded 500: 500 is the hypothetical maximum on the scale.<ref>{{cite news |last1=Wong |first1=Edward |title=On Scale of 0 to 500, Beijing's Air Quality Tops 'Crazy Bad' at 755 |url=https://www.nytimes.com/2013/01/13/science/earth/beijing-air-pollution-off-the-charts.html#:~:text=According%20to%20an%20article%20in%20the%20New,is%20the%20terminology%20for%20levels%20above%20500. |access-date=24 April 2026 |work=The New York Times |date=13 January 2013}}</ref><ref name=":17">{{Cite news |last=Wong |first=Edward |date=2013-03-21 |title=As Pollution Worsens in China, Solutions Succumb to Infighting |url=https://www.nytimes.com/2013/03/22/world/asia/as-chinas-environmental-woes-worsen-infighting-emerges-as-biggest-obstacle.html |access-date=2026-04-23 |work=The New York Times |language=en-US |issn=0362-4331}}</ref> On January 12, 2013, Beijing reported a "jaw-dropping" all-time high AQI of 755,<ref name=":17" /> the highest of 18 of 24 hourly readings that were "beyond index". This corresponded to a PM2.5 concentration of {{val|886|u=ug|up=m3}}, far beyond the WHO's then-recommended daily level of {{val|25|u=ug|up=m3}}.<ref>{{Cite news |date=January 13, 2013 |title=Beijing air pollution off the charts |work= CBS News |url=https://www.cbsnews.com/news/beijing-air-pollution-off-the-charts/ |access-date=2026-04-23 |language=en-US}}</ref><ref>{{cite journal |last1=Zhang |first1=R. |last2=Jing |first2=J. |last3=Tao |first3=J. |last4=Hsu |first4=S.-C. |last5=Wang |first5=G. |last6=Cao |first6=J. |last7=Lee |first7=C. S. L. |last8=Zhu |first8=L. |last9=Chen |first9=Z. |last10=Zhao |first10=Y. |last11=Shen |first11=Z. |title=Chemical characterization and source apportionment of PM 2.5 in Beijing: seasonal perspective |journal=Atmospheric Chemistry and Physics |date=25 July 2013 |volume=13 |issue=14 |pages=7053–7074 |doi=10.5194/acp-13-7053-2013 |doi-access=free |url=http://www.klacp.ac.cn/kycg/fbwz/201503/P020250220553302956925.pdf}}</ref>

In 2013, China introduced an Air Pollution Prevention and Control Action Plan to reduce pollution levels.<ref name="Yang2026">{{cite journal |last1=Yang |first1=Yang |last2=Yang |first2=Hongyan |last3=Ye |first3=Jing |last4=Yang |first4=Guanglei |last5=Deng |first5=Zhiyu |last6=Li |first6=Dequan |title=From lenient to stringent: Environmental policy target adjustment and the decline in mortality |journal=Economic Analysis and Policy |date=1 June 2026 |volume=91 |pages=647–667 |doi=10.1016/j.eap.2026.03.039 |issn=0313-5926}}</ref> Since then, air quality in China has shown substantial improvements thanks to clean air actions.<ref>{{Cite journal |last1=Zhong |first1=Junting |last2=Zhang |first2=Xiaoye |last3=Gui |first3=Ke |last4=Liao |first4=Jie |last5=Fei |first5=Ye |last6=Jiang |first6=Lipeng |last7=Guo |first7=Lifeng |last8=Liu |first8=Liangke |last9=Che |first9=Huizheng |last10=Wang |first10=Yaqiang |last11=Wang |first11=Deying |last12=Zhou |first12=Zijiang |date=12 July 2022 |title=Reconstructing 6-hourly PM{{sub|2.5}} datasets from 1960 to 2020 in China |journal=Earth System Science Data |volume=14 |issue=7 |pages=3197–3211 |doi=10.5194/essd-14-3197-2022 |bibcode=2022ESSD...14.3197Z |doi-access=free }}</ref><ref>{{cite journal |last1=Wang |first1=J |last2=Wu |first2=Q |last3=Liu |first3=J |last4=Yang |first4=H |last5=Yin |first5=M |last6=Chen |first6=S |last7=Guo |first7=P |last8=Ren |first8=J |last9=Luo |first9=X |last10=Linghu |first10=W |last11=Huang |first11=Q |title=Vehicle emission and atmospheric pollution in China: problems, progress, and prospects. |journal=PeerJ |date=2019 |volume=7 |article-number=e6932 |doi=10.7717/peerj.6932 |doi-access=free |pmid=31143547 |pmc=6526014 |bibcode=2019PeerJ...7e6932W }}</ref> From 2013-2017, annual average PM{{sub|2.5}} concentrations declined by 33.3% across 74 major Chinese cities.<ref name="Wang2026"/> As of 2021, PM{{sub|2.5}} mass and toxicity had also decreased.<ref>{{cite journal |last1=Zheng |first1=H |last2=Wu |first2=D |last3=Wang |first3=S |last4=Li |first4=X |last5=Jin |first5=LN |last6=Zhao |first6=B |last7=Li |first7=S |last8=Sun |first8=Y |last9=Dong |first9=Z |last10=Wu |first10=Q |last11=Chen |first11=X |last12=Liu |first12=Y |last13=Chen |first13=J |last14=Tian |first14=H |last15=Liu |first15=Q |last16=Jiang |first16=J |last17=Kan |first17=H |last18=He |first18=K |last19=He |first19=H |last20=Chen |first20=C |last21=Zhao |first21=J |last22=Weichenthal |first22=S |last23=Ji |first23=JS |last24=Cohen |first24=AJ |last25=Hao |first25=J |last26=Li |first26=Q |title=Control of toxicity of fine particulate matter emissions in China. |journal=Nature |date=July 2025 |volume=643 |issue=8071 |pages=404–411 |doi=10.1038/s41586-025-09158-w |pmid=40634743 |bibcode=2025Natur.643..404Z }}</ref> Reductions in PM{{sub|2.5}} are associated with decreases in mortality rate.<ref name="Yang2026" /> In Beijing, annual average concentrations of PM2.5 showed a decrease of 65.9% from 2013 to 2024. Beijing also set a record in 2024 with 290 days as the number of good/moderate air quality days since the beginning of monitoring.<ref name="Juan">{{cite news |last1=Juan |first1=Du |title=Beijing achieves record air quality in 2024 |url=https://www.chinadaily.com.cn/a/202505/09/WS681d9f6aa310a04af22be634.html |access-date=24 April 2026 |work=China Daily |date=2025-05-09}}</ref><ref>{{cite news |title=290 Days: A New Record! |url=https://english.beijing.gov.cn/latest/news/202505/t20250512_4087121.html |access-date=24 April 2026 |work=english.beijing.gov.cn |date=2025-05-12}}</ref>

===Europe=== [[File:European Environment Agency Annual mean PM2.5 concentrations in 2023.png|thumb|400px|Map of annual mean PM2.5 concentrations in 2023, European Environment Agency<ref name="EEA2023">{{cite web |title=Particulate matter - PM2.5 |url=https://www.eea.europa.eu/en/analysis/publications/air-quality-status-report-2025/particulate-matter-pm2.5 |website=European Environment Agency |access-date=27 March 2026 |language=en |date=9 April 2025}}</ref>]] Europe continues to experience poor air quality. In 2021, the World Health Organization strengthened its guideline levels on annual PM2.5, lowering its recommended guideline from 10 μg/m3 to 5 μg/m3.<ref name="ChenG"/><ref name="who-9789240034228" /> In 2023, the European Environment Agency (EEA) reported that while only 1.2% of its monitoring stations reported concentrations of PM2.5 above the EU annual limit value (25 μg/m3), 92% registered concentrations above the WHO annual guideline level (5 μg/m3).<ref name="EEA2023"/>

Europe has a well-established air quality research infrastructure. Year-long datasets of organic aerosols (OA), a key component of total submicron particulate matter (PM1), were collected from 2013–2019 from both non-urban and urban sites. Depending on location, between 20 and 90% of the mass of PM1 was attributed to organic aerosols (OA). It was possible to identify contributions from specific sources. For example, solid fuel combustion contributed 16% yearly, being lowest during the summer and rising to 24% during the winter months. Overall PM1 (including organic aerosols, black carbon, nitrate, sulfate, ammonium, and chloride) averaged 9.7 ± 7.9 μg/m3, and was generally higher at urban than non-urban sites. Among the patterns observed, urban sites showed characteristic morning and evening peaks due to rush-hour traffic. Both urban and rural sites showed reduced values during the day and a marked evening peak due to particulates from biomass burning for heating. The impact of traffic was lower on weekends, cooking was higher on evenings and weekends, and wood-burning (e.g. open fire grills and residential heating) was also higher on weekends.<ref name="ChenG"/>

===South Korea=== As of 2017, South Korea has the worst air pollution among the developed nations in the OECD (Organization for Economic Cooperation and Development).<ref>{{cite web| last1=Hu| first1=Elise|url=https://www.npr.org/sections/parallels/2017/10/10/552264719/armed-with-nasa-data-south-korea-confronts-its-choking-smog | title=Armed With NASA Data, South Korea Confronts Its Choking Smog| website=NPR| date=10 October 2017}}</ref> According to a study conducted by NASA and NIER, 52% of PM{{sub|2.5}} measured in Olympic Park, Seoul in May and June 2016 came from local emissions. The rest was trans-boundary pollution coming from China's Shandong Province (22%), North Korea (9%), Beijing (7%), Shanghai (5%), and a combined 5% from China's Liaoning Province, Japan and the West Sea.<ref>{{cite web |url=https://english.hani.co.kr/arti/english_edition/e_international/803654.html |title=NASA and NIER study finds that 48% of particulate matter comes from outside S. Korea }}</ref> In December 2017, the environmental ministers from South Korea and China signed the China-Korea Environmental Cooperation Plan (2018–22), a five-year plan to jointly solve issues in the air, water, soil and waste. An environmental cooperation centre was also launched in 2018 to aid cooperation.<ref>{{cite web| url=https://asianews.eu/content/china-south-korea-build-environment-cooperation-75620| title=China, South Korea build environment cooperation| date=26 June 2018| access-date=3 May 2023| archive-date=23 September 2022| archive-url=https://web.archive.org/web/20220923153058/https://asianews.eu/content/china-south-korea-build-environment-cooperation-75620| url-status=live}}</ref>

===Thailand=== PM{{sub|2.5}} and PM{{sub|10}} pose serious health risks and are linked to high mortality rates in Thailand. They show seasonal variation: in urban areas of Thailand such as its capital, Bangkok, concentrations and PM{{sub|2.5}} exposure risk are higher during the cool dry season (December to February).<ref name="Ahmad">{{cite journal |last1=Ahmad |first1=Mushtaq |last2=Panyametheekul |first2=Sirima |last3=Thaveevong |first3=Phailin |last4=Ngamsritrakul |first4=Thawat |last5=Tassaneetrithep |first5=Boonrat |last6=Supasri |first6=Titaporn |last7=Bennett |first7=Chonlada |title=Long-term monitoring of PM2.5 and PM10: Implications for air quality and public health in urban Bangkok, Thailand |journal=Environmental Challenges |date=1 December 2025 |volume=21 |article-number=101312 |doi=10.1016/j.envc.2025.101312 |url=https://www.sciencedirect.com/science/article/pii/S2667010025002318 |issn=2667-0100}}</ref><ref name="Sukkhum">{{cite journal |last1=Sukkhum |first1=Sarawut |last2=Lim |first2=Apiradee |last3=Ingviya |first3=Thammasin |last4=Saelim |first4=Rattikan |title=Seasonal Patterns and Trends of Air Pollution in the Upper Northern Thailand from 2004 to 2018 |journal=Aerosol and Air Quality Research |date=2022 |volume=22 |issue=5 |article-number=210318 |doi=10.4209/aaqr.210318 |bibcode=2022AAQR...22u0318S |url=https://aaqr.org/articles/aaqr-21-11-oa-0318 |language=en |issn=2071-1409}}</ref>

PM{{sub|2.5}} levels and associated health risks tend to be worse in northern areas such as Chiang Mai.<ref>{{cite journal |last1=Pisithkul |first1=T |last2=Pisithkul |first2=T |last3=Lao-Araya |first3=M |title=Impact of Air Pollution and Allergic Status on Health-Related Quality of Life among University Students in Northern Thailand. |journal=International Journal of Environmental Research and Public Health |date=8 April 2024 |volume=21 |issue=4 |page=452 |doi=10.3390/ijerph21040452 |doi-access=free |pmid=38673363 |pmc=11050436 }}</ref> The mountains that surround Chiang Mai interfere with air flow and cause temperature inversions that trap pollution. <ref name="NASA2026">{{cite news |title=Image of the Day: Smoke Shrouds Northern Thailand - NASA Science |url=https://science.nasa.gov/earth/earth-observatory/smoke-shrouds-northern-thailand/ |access-date=24 April 2026 |work=NASA Earth Observatory |date=23 April 2026}}</ref> In 2023, Chiang Mai, a popular tourist destination, was ranked as the most polluted of 100 cities worldwide by a Swiss air quality company.<ref>{{cite web | url=https://www.theguardian.com/world/2023/mar/27/air-pollution-chokes-thailand-as-campaigners-call-for-stricter-laws-chiang-mai | title=Air pollution chokes Thailand as campaigners call for stricter laws| website=TheGuardian.com| date=27 March 2023}}</ref><ref>{{cite web| url=https://airqualitynews.com/2023/03/13/air-pollution-hospitalises-200000-in-one-week-as-fumes-emissions-and-smoke-descend-on-thailand/| title=Air pollution hospitalises 200,000 in one week as fumes, emissions and smoke descend on Thailand| date=13 March 2023| access-date=28 March 2023| archive-date=28 March 2023| archive-url=https://web.archive.org/web/20230328102910/https://airqualitynews.com/2023/03/13/air-pollution-hospitalises-200000-in-one-week-as-fumes-emissions-and-smoke-descend-on-thailand/| url-status=live}}</ref>

In March and April 2026, Chang Mai smog reached dangerous PM{{sub|2.5}} levels as a result of fires during the burning season (January through April), with dense haze and reduced visibility across the region.<ref name="Vis">{{cite web |last1=Vis |first1=Arnold |title=What is the Burning Season in Thailand? Impact Teaching |url=https://www.impact-teaching.com/blog/what-is-the-burning-season-in-thailand/ |website=Impact Teaching |access-date=24 April 2026 |date=19 March 2025}}</ref><ref name="Bhardwaj"/><ref name="Sexton">{{cite news |last1=Sexton |first1=Chrissy |title=Chiang Mai's mountain views vanish as smoke fills the valleys |url=https://www.earth.com/image/chiang-mais-mountain-views-vanish-as-smoke-fills-the-valleys/ |access-date=24 April 2026 |work=Earth.com |date=April 23, 2026 |language=en}}</ref><ref name="NASA2026"/> On March 30, 2026, PM{{sub|2.5}} levels were reported as {{val|188|u=ug|up=m3}}.<ref name="Bhardwaj">{{cite news |last1=Bhardwaj |first1=Shashank |title=Chiang Mai Chokes: Inside Thailand's Worst Air Crisis of 2026 |url=https://openthemagazine.com/world/chiang-mai-chokes-inside-thailands-worst-air-crisis-of-2026 |access-date=24 April 2026 |work=Open Magazine |date=1 April 2026 |language=en}}</ref> Particulate matter levels in southern Thailand are also increasing as a result of open crop residue burning in Thailand and nearby Southeast Asian countries.<ref>{{cite journal |last1=Lim |first1=Apiradee |last2=Owusu |first2=Benjamin Atta |last3=Thongrod |first3=Thitaporn |last4=Khurram |first4=Haris |last5=Pongsiri |first5=Nitinun |last6=Ingviya |first6=Thammasin |last7=Buya |first7=Suhaimee |title=Trend and Association Between Particulate Matters and Meteorological Factors: A Prospect for Prediction of PM2.5 in Southern Thailand |journal=Polish Journal of Environmental Studies |date=5 July 2025 |volume=34 |issue=5 |pages=5215–5223 |doi=10.15244/pjoes/190787 |bibcode=2025PJES...34.5215L }}</ref>

=== Mongolia === Mongolia's capital city Ulaanbaatar has an annual average mean temperature of about 0 °C, making it the world's coldest capital city.<ref>{{cite web|url=https://www.worldatlas.com/articles/the-coldest-capital-cities-in-the-world.html|title=The Coldest Capital Cities In The World|last=Sen Nag|first=Oishimaya|publisher=WorldAtlas|date=2021-01-21|access-date=2022-12-12}}</ref> Ulaanbaatar is located in the Tuul River Valley, surrounded by the Khentii Mountains, conditions which tend to cause temperature inversions and trap air pollution. Temperature inversions are strongly correlated with particulate matter concentrations.<ref name="Mingyeong"/>

The use of coal and wood as fuels has been identified as a major source of air pollution.<ref name="Mingyeong">{{cite journal |last1=Kim |first1=Mingyeong |last2=Ha |first2=Yoonkyeong |last3=Kim |first3=Jeongbeen |last4=Lee |first4=Ji Yi |last5=Kim |first5=Yong Pyo |last6=Natsagdorj |first6=Amgalan |last7=Kim |first7=Changhyuk |title=First real-time size distribution measurements of aerosol particles in Ulaanbaatar, Mongolia |journal=Atmospheric Environment |date=5 March 2025 |volume=345 |article-number=121052 |doi=10.1016/j.atmosenv.2025.121052 |bibcode=2025AtmEn.34521052K |url=https://www.sciencedirect.com/science/article/abs/pii/S1352231025000275 |issn=1352-2310}}</ref> Heating mainly comes from coal. Coal is burned in power stations, heating the apartments of about 40% of the population, and in stoves in traditional Ger housing, home to the other 60% of the population.<ref name="Warburton">{{cite journal |last1=Warburton |first1=D |last2=Warburton |first2=N |last3=Wigfall |first3=C |last4=Chimedsuren |first4=O |last5=Lodoisamba |first5=D |last6=Lodoysamba |first6=S |last7=Jargalsaikhan |first7=B |title=Impact of Seasonal Winter Air Pollution on Health across the Lifespan in Mongolia and Some Putative Solutions. |journal=Annals of the American Thoracic Society |date=April 2018 |volume=15 |issue=Suppl 2 |pages=S86–S90 |doi=10.1513/AnnalsATS.201710-758MG |pmid=29676634 |pmc=6850795 }}</ref> Ger districts or shantytowns have developed due to the country's new market economy and the very cold winter seasons. The poor in these districts cook and heat their wood houses with indoor stoves fueled by wood or coal. The resulting air pollution is characterized by extremely high levels of particulate matter, carbon, sulfur dioxide, nitrogen oxide, iron, arsenic, lead, zinc, and nickel.<ref name="Galsuren">{{cite journal |last1=Galsuren |first1=J |last2=Dambadarjaa |first2=D |last3=Tighe |first3=RM |last4=Gray |first4=GC |last5=Zhang |first5=J |title=Particulate Matter Exposure and Viral Infections: Relevance to Highly Polluted Settings such as Ulaanbaatar, Mongolia. |journal=Current Environmental Health Reports |date=23 April 2025 |volume=12 |issue=1 |page=22 |doi=10.1007/s40572-025-00484-9 |pmid=40268823 |pmc=12150858 |bibcode=2025CEHR...12...22G }}</ref> Burning coal also produces fly ash, which contains fine dust particles in the PM2.5 size range.<ref>{{cite journal |last1=Zheng |first1=Yanmin |last2=Zhao |first2=Lei |last3=French |first3=David |last4=Graham |first4=Ian |last5=Wei |first5=Qiang |last6=Dai |first6=Shifeng |last7=Feng |first7=Lili |title=Revisiting sustainable resources in the combustion products of alumina-rich coal: Critical metal (Li, Ga, Nb, and REY) potential of ash from the Togtoh Power Plant, Inner Mongolia, China |journal=Science of the Total Environment |date=10 November 2024 |volume=950 |article-number=175056 |doi=10.1016/j.scitotenv.2024.175056 |pmid=39094637 |bibcode=2024ScTEn.95075056Z |url=https://www.sciencedirect.com/science/article/pii/S0048969724052069 |issn=0048-9697}}</ref>

Pollution in Ulaanbaatar is 4–11 times higher during the winter than other seasons, with primary emissions from combustion contributing prominently to winter air pollution.<ref name="Batbold">{{cite journal |last1=Batbold |first1=C |last2=Narmandakh |first2=M |last3=Batjargal |first3=B |last4=Byambaa |first4=B |last5=Chonokhuu |first5=S |title=An annual result of outdoor and indoor PM 2.5 analysis in two different building types in Ulaanbaatar, Mongolia. |journal=Environmental Monitoring and Assessment |date=13 September 2024 |volume=196 |issue=10 |page=932 |doi=10.1007/s10661-024-13102-2 |pmid=39271556 |bibcode=2024EMnAs.196..932B }}</ref> PM2.5 levels are elevated during the heating season, starting to rise in October and dropping by April. During peak heating season, November to February, hourly averaged PM2.5 concentrations can exceed {{val|1000|u=ug|up=m3}}, an extremely dangerous level.<ref name="Batbold" /> As of 2021, the World Health Organization's recommended annual mean PM{{sub|10}} limit is {{val|15|u=ug|up=m3}}.<ref>{{Cite web |date=22 September 2021 |title=What are the WHO Air quality guidelines? |url=https://www.who.int/news-room/feature-stories/detail/what-are-the-who-air-quality-guidelines |access-date=2026-04-22 |website=World Health Organization (WHO) |language=en}}</ref><ref name="who-9789240034228" /> Winter air pollution in Ulaanbaatar has been linked to seasonal decreases in conception rates and birth outcomes, among other negative health outcomes.<ref name="Badarch">{{cite journal |last1=Badarch |first1=J |last2=Harding |first2=J |last3=Dickinson-Craig |first3=E |last4=Azen |first4=C |last5=Ong |first5=H |last6=Hunter |first6=S |last7=Pannaraj |first7=PS |last8=Szepesi |first8=B |last9=Sereenendorj |first9=T |last10=Davaa |first10=S |last11=Ochir |first11=C |last12=Warburton |first12=D |last13=Readhead |first13=C |title=Winter Air Pollution from Domestic Coal Fired Heating in Ulaanbaatar, Mongolia, Is Strongly Associated with a Major Seasonal Cyclic Decrease in Successful Fecundity. |journal=International Journal of Environmental Research and Public Health |date=9 March 2021 |volume=18 |issue=5 |page=2750 |doi=10.3390/ijerph18052750 |doi-access=free |pmid=33803108 |pmc=7967474 }}</ref>

Since 2010, rapid growth and uneven patterns of economic development have worsened poverty and air pollution.<ref name="Sanduijav">{{cite journal |last1=Sanduijav |first1=Chimedregzen |last2=Ferreira |first2=Susana |last3=Filipski |first3=Mateusz |last4=Hashida |first4=Yukiko |title=Air pollution and happiness: Evidence from the coldest capital in the world |journal=Ecological Economics |date=1 September 2021 |volume=187 |article-number=107085 |doi=10.1016/j.ecolecon.2021.107085 |bibcode=2021EcoEc.18707085S |issn=0921-8009}}</ref> Mongolia has introduced a number of initiatives to improve availability of heating sources, fuels, and stoves.<ref name="Cousins"/> As of May 15, 2019, the Mongolian government introduced a ban on the burning of raw coal in Ulaanbaatar. Refined coal briquettes with lower emissions were subsidized as an alternative fuel, resulting in a reported 60% reduction in PM{{sub|10}} for the 2019-2020 winter.<ref name="Cousins">{{cite journal |last1=Cousins |first1=Sophie |title=Air pollution in Mongolia. |journal=Bulletin of the World Health Organization |date=1 February 2019 |volume=97 |issue=2 |pages=79–80 |doi=10.2471/BLT.19.020219 |pmid=30728613 |pmc=6357570 }}</ref>

===United States=== Following implementation of the Clean Air Act in 1970, air quality in the U.S. improved, with a reduction of 79% in combined emissions of criteria and precursor pollutants from 1970-2024. From 2000-2024, PM{{sub|2.5}} levels have decreased by 46% (Annual) and 45% (24-Hour), while PM{{sub|10}} has decreased by 36% (24-Hour).<ref name="EPA2024">{{cite web |title=Our Nation's Air: Trends Through 2024 |url=https://gispub.epa.gov/air/trendsreport/2025/#home |website=gispub.epa.gov |publisher=U.S. Environmental Protection Agency |access-date=23 April 2026 |language=en}}</ref>

Since 2018, wildfires have been a source of large amounts of particulate matter and ozone. In 2020, 1.7 million hectares burned in California. In 2023, wildfires in Canada contributed to large numbers of "smoke days" across the continental United States.<ref name="EPA2024"/><ref name="Nagele">{{cite news |last1=Nagele |first1=Rose |title=Wildfire smoke impacted air quality across the United States from 2018 to 2023 |url=https://cpo.noaa.gov/wildfire-smoke-impacted-air-quality-across-the-united-states-from-2018-to-2023/ |access-date=23 April 2026 |work=Climate Program Office |date=16 August 2024}}</ref><ref name="Lee2024">{{cite journal |last1=Lee |first1=Haebum |last2=Jaffe |first2=Daniel A. |title=Wildfire Impacts on O3 in the Continental United States Using PM2.5 and a Generalized Additive Model (2018–2023) |journal=Environmental Science & Technology |date=20 August 2024 |volume=58 |issue=33 |pages=14764–14774 |doi=10.1021/acs.est.4c05870 |pmid=39120533 |pmc=11340019 |bibcode=2024EnST...5814764L |issn=0013-936X}}</ref><ref name="Thilakaratne">{{cite journal |last1=Thilakaratne |first1=R |last2=Hoshiko |first2=S |last3=Rosenberg |first3=A |last4=Hayashi |first4=T |last5=Buckman |first5=JR |last6=Rappold |first6=AG |title=Wildfires and the Changing Landscape of Air Pollution-related Health Burden in California. |journal=American Journal of Respiratory and Critical Care Medicine |date=1 April 2023 |volume=207 |issue=7 |pages=887–898 |doi=10.1164/rccm.202207-1324OC |pmid=36520960 |pmc=11972552 }}</ref>

<gallery mode=nolines class=center widths=460px heights=350px> File:Naaqs-concentrations-averages-data-1990-2024.png|Declining National Air Pollutant Concentration Averages in the United States, 1990-2024 File:Naaqs-emissions-categories-data.png | National Emissions of Pollutants By Source Category, United States, 2024 File:US-PM25-nonattainment-2026-02.pdf|U.S. counties violating national PM{{sub|2.5}} standards, February 2026 File:US-PM10-nonattainment-2018-06.png|U.S. counties violating national PM{{sub|10}} standards, June 2018 </gallery> {{Clear}}

== Notes == {{notelist|30em}}

== References == {{Reflist|30em}}

== Further reading == * {{cite book |last1=Hinds |first1=William C. |last2=Zhu |first2=Yifang |title=Aerosol technology: properties, behavior, and measurement of airborne particles |date=2022 |publisher=Wiley |location=Hoboken, NJ |isbn=978-1-119-49404-1 |edition=Third}} * {{Cite web |url=https://undark.org/breathtaking/ |title=The Weight of Numbers: Air Pollution and PM{{sub|2.5}} |access-date=23 August 2025 |date=9 August 2018 |last= |publisher=Undark}}

== External links == === Control === * {{Cite web | url=https://www.epa.gov/indoor-air-quality-iaq/best-practices-indoor-air-quality-when-remodeling-your-home | title=Best Practices for Indoor Air Quality when Remodeling Your Home | website=US EPA| date=7 January 2015 }} * {{Cite web | url=https://www.epa.vic.gov.au/for-business/find-a-topic/dust/advice-for-businesses/work-based-examples | title=Dust: Learn about the impact of dust pollution, what the law says about dust and what you can do to manage it. | website=EPA Victoria | date=25 June 2025 }} * [https://www.hse.gov.uk/pubns/cis69.pdf Controlling construction dust with on-tool extraction (4 page PDF with photos)] * [https://www.hse.gov.uk/lev/what-is-ileve.htm What is Local Exhaust Ventilation (LEV)?], GOV.UK * [https://www.hse.gov.uk/welding/protect-your-workers/index.htm Welding fume: protect your workers], GOV.UK * [https://s3.ap-southeast-1.amazonaws.com/hkca.com.hk/upload/doc/publication/20190813_v8-1-full-YppIK.pdf Environmental Toolbox Training Kit], August 2019, from the [https://hkca.com.hk/publications Hong Kong Construction Association] with many illustrated useful tips on particle pollution control. [https://web.archive.org/web/20230703095444/https://s3.ap-southeast-1.amazonaws.com/hkca.com.hk/upload/doc/publication/20190813_v8-1-full-YppIK.pdf Archived] from original on 3 July 2023.

=== Others === * [https://www.youtube.com/watch?v=4eh6IKahbok NASA's Earth Minute: My Name is Aerosol] * [https://earth.nullschool.net/#current/particulates/surface/level/overlay=pm1/winkel3 Current global map of PM{{sub|1}} distribution] | [https://earth.nullschool.net/#current/particulates/surface/level/overlay=pm2.5/winkel3 Current global map of PM{{sub|1}} and PM{{sub|2.5}} distribution] | [https://earth.nullschool.net/#current/particulates/surface/level/overlay=pm10/winkel3 Current global map of PM{{sub|1}}, PM{{sub|2.5}} and PM{{sub|10}} distribution] * [https://earth.nullschool.net/#current/particulates/surface/level/overlay=organic_matter_aot/winkel3 Current global map of the aerosol optical thickness of organic matter in green light] * [https://aqicn.org/map/world/#@g/2.0574/7.9102/2z Air Pollution in World: Real-time Air Quality Index Visual Map] | [https://aqicn.org/contact/ About] * [https://www.airvisual.com/air-quality-map Air quality map] | [https://www.unep.org/news-and-stories/press-release/worlds-largest-platform-air-quality-data-launched-tenth-world-urban About] * [https://www.aqhi.gov.hk/en/health-advice/sources-of-air-pollutants9b5f.html?start=5 Sources of Respirable and Fine Suspended Particulates]. EPD HK. *[https://web.archive.org/web/20230921162516/https://www.aqhi.gov.hk/en/health-advice/sources-of-air-pollutantsa37a.html?showall=&start=5 Archived] from original on 21 September 2024.

{{Authority control}} {{Aerosol terminology|state=expanded}} {{Severe weather terminology (United States) navbox}} {{Pollution|state=collapsed}} {{human impact on the environment}} {{HVAC}}

Category:Particulates Category:Aerosols Category:Pollutants Category:Visibility Category:Air pollution Category:Climate forcing Category:Articles containing video clips Category:Pollution Category:IARC Group 1 carcinogens