Air pollution

Part of a series on
Pollution
Air pollution from a factory
Air Air quality index Atmospheric dispersion modeling Chlorofluorocarbon Combustion Exhaust gas Haze Global dimming Global distillation Indoor air quality Ozone depletion Particulates Persistent organic pollutant Smog Soot Volatile organic compound Waste
Biological Biological hazard Genetic Introduced species Invasive species
Digital Information
Electromagnetic Light Ecological Overillumination Radio spectrum
Natural Ozone Radium and radon in the environment Volcanic ash Wildfire
Noise Transportation Marine mammals and sonar Noise control
Radiation Actinides Bioremediation Depleted uranium Nuclear fission Nuclear fallout Plutonium Poisoning Radioactivity Uranium Radioactive waste
Soil Agricultural Land degradation Bioremediation Defecation Electrical resistance heating Soil guideline values Phytoremediation
Solid waste Advertising mail Biodegradable waste Brown waste Electronic waste Foam food container Food waste Green waste Hazardous waste Industrial waste Litter Mining Municipal solid waste Nanomaterials Plastic Packaging waste Post-consumer waste Waste management
Space Space debris
Thermal Urban heat island
Visual Air travel Advertising clutter Overhead power lines Traffic signs Vandalism
War Chemical warfare Herbicidal warfare Agent Orange Nuclear holocaust Nuclear fallout Nuclear famine Nuclear winter Scorched earth Unexploded ordnance War and environmental law
Water Agricultural wastewater Biosolids Diseases Eutrophication Firewater Freshwater Groundwater Hypoxia Industrial wastewater Marine Monitoring Nonpoint source Nutrient Ocean acidification Oil spill Pharmaceuticals Freshwater salinization Septic tanks Sewage Shipping Sludge Stagnation Sulfur water Surface runoff Turbidity Urban runoff Water quality Wastewater
Topics History Pollutants Heavy metals Paint
Misc Area source Debris Dust Garbology Legacy Midden Point source Waste Lists Diseases Law by country Most polluted cities Least polluted cities by PM2.5 Treaties Categories By country
Environment portal  Ecology portal
v t e

Part of a series on
Weather
Temperate and polar seasons Winter Spring Summer Autumn
Tropical seasons Dry season Harmattan Wet season
Storms Cloud Cumulonimbus cloud Arcus cloud Downburst Microburst Heat burst Derecho Lightning Volcanic lightning Thunderstorm Air-mass thunderstorm Thundersnow Dry thunderstorm Mesocyclone Supercell Tornado Anticyclonic tornado Landspout Waterspout Dust devil Fire whirl Anticyclone Cyclone Polar low Extratropical cyclone European windstorm Nor'easter Subtropical cyclone Tropical cyclone Atlantic hurricane Typhoon Storm surge Dust storm Simoom Haboob Monsoon Amihan Gale Sirocco Firestorm Winter storm Ice storm Blizzard Ground blizzard Snow squall
Precipitation Drizzle Freezing Graupel Hail Megacryometeor Ice pellets Diamond dust Rain Freezing Cloudburst Snow Rain and snow mixed Snow grains Snow roller Slush
Topics Air pollution Atmosphere Chemistry Convection Physics River Climate Cloud Physics Fog Mist Season Cold wave Heat wave Jet stream Meteorology Severe weather List Extreme Severe weather terminology Canada Japan United States Weather forecasting Weather modification
Glossaries Meteorology Climate change Tornado terms Tropical cyclone terms
Weather portal
v t e

Air pollution is the contamination of air due to the presence of substances called pollutants in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials.

Air pollution is the largest environmental risk factor for disease and premature death[5]^[14] and the fourth largest risk factor overall for human health.^[15] Air pollution causes the premature deaths of around 7 million people worldwide each year,^[5] or a global mean loss of life expectancy (LLE) of 2.9 years,^[16] and there has been no significant change in the number of deaths caused by all forms of pollution since at least 2015.^[14][17][18] Outdoor air pollution attributable to fossil fuel use alone causes ~3.61 million deaths annually,^[19] making it one of the top contributors to human death.^[5] Anthropogenic ozone causes around 470,000 premature deaths a year and fine particulate (PM_2.5) pollution around another 2.1 million.^[20] The scope of the air pollution crisis is large: In 2018, WHO estimated that "9 out of 10 people breathe air containing high levels of pollutants."^[21] Although the health consequences are extensive, the way the problem is handled is considered largely haphazard^[22][21][23] or neglected.^[14]

The World Bank has estimated that welfare losses (premature deaths) and productivity losses (lost labour) caused by air pollution cost the world economy $5 trillion per year.^[24][25][26] The costs of air pollution are generally an externality to the contemporary economic system and most human activity, although they are sometimes recovered through monitoring, legislation, and regulation.^[27][28]

Many different technologies and strategies are available for reducing air pollution.

There are many different sources of air pollution. Some air pollutants (such as nitrogen oxides) originate mainly from human activities,[39] while some (notably radon gas) come mostly from natural sources.^[40] However, many air pollutants (including dust and sulfur dioxide) come from a mixture of natural and human sources.^[41]

Anthropogenic (human-made) sources

• Stationary sources include:
  • environmental impact of the coal industry)^[42]
    • Oil and gas sites that have
      methane leaks^{[43][44][45][46]}
  • burning of traditional biomass such as wood, crop waste and dung. (In developing and poor countries,[47] traditional biomass burning is the major source of air pollutants.^[48][49] It is also the main source of particulate pollution in many developed areas including the UK & New South Wales.^[50][51] Its pollutants include PAHs.^[52])
  • manufacturing facilities (factories)^[53]
    • a 2014 study found that in China equipment-,
      emission factors in its industrial structure.^[55]
  • construction[56]^[57]
  • waste incineration (incinerators as well as open and uncontrolled fires of mismanaged waste, making up about a fourth of municipal solid terrestrial waste)^[58][59]
  • furnaces and other types of fuel-burning heating devices^[60]
• air pollution externality of cars enters the air from the exhaust gas and car tires (including microplastics^[63]). Road vehicles make a significant amount of all air pollution (typically, for example, around a third to a half of all nitrogen dioxide emissions)^[64][65][66] and are a major driver of climate change.^[67][68]
• Agriculture and forest management strategies using controlled burns. Practices like slash-and-burn in forests like the Amazon cause large air pollution with the deforestation.^[69] Controlled or prescribed burning is a practice used in forest management, agriculture, prairie restoration, and greenhouse gas reduction.^[70] Foresters can use controlled fire as a tool because fire is a natural feature of both forest and grassland ecology.^[71][72] Controlled burning encourages the sprouting of some desirable forest trees, resulting in a forest renewal.^[73]

There are also sources from processes other than combustion:

• Fumes from paint,
  volatile organic compounds in the Los Angeles basin in the 2010s.^[74]
• Waste deposition in landfills produces methane^[75] and open burning of waste releases harmful substances.^[76]
• Nuclear weapons, toxic gases, germ warfare, and rocketry are examples of military resources.^[77]
• emissions from meat production or livestock contribute substantially to air pollution^[78][79]
  • Fertilized farmland may be a major source of nitrogen oxides.^[80]

Natural sources

• Dust from natural sources, usually large areas of land with little vegetation or no vegetation
• Methane, emitted by the digestion of food by animals, for example cattle
• Radon gas from radioactive decay within the Earth's crust. Radon is a colorless, odorless, naturally occurring, radioactive noble gas that is formed from the decay of radium. It is considered to be a health hazard. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as the basement and it is the second most frequent cause of lung cancer, after cigarette smoking.
• Smoke and
  wildfires. During periods of active wildfires, smoke from uncontrolled biomass combustion can make up almost 75% of all air pollution by concentration.^[82]
• anthropogenic organic carbon compounds – to produce a seasonal haze of secondary pollutants.^[83] Black gum, poplar, oak and willow are some examples of vegetation that can produce abundant VOCs. The VOC production from these species result in ozone levels up to eight times higher than the low-impact tree species.^[84]
• Volcanic activity, which produces sulfur, chlorine, and ash particulates^[85]

Emission factors

Air pollutant emission factors are reported representative values that aim to link the quantity of a pollutant released into the ambient air to an activity connected with that pollutant's release.^{[2][86][87][88]} The weight of the pollutant divided by a unit weight, volume, distance, or time of the activity generating the pollutant is how these factors are commonly stated (e.g., kilograms of particulate emitted per tonne of coal burned). These criteria make estimating emissions from diverse sources of pollution easier. Most of the time, these components are just averages of all available data of acceptable quality, and they are thought to be typical of long-term averages.

The Stockholm Convention on Persistent Organic Pollutants identified pesticides and other persistent organic pollutants of concern. These include dioxins and furans which are unintentionally created by combustion of organics, like open burning of plastics, and are endocrine disruptors and mutagens.

The United States Environmental Protection Agency has published a compilation of air pollutant emission factors for a wide range of industrial sources.^[89] The United Kingdom, Australia, Canada, and many other countries have published similar compilations, as well as the European Environment Agency.^{[90][91][92][93]}

Pollutants

An air pollutant is a material in the air that can have many effects on humans and the ecosystem.^[94] The substance can be solid particles, liquid droplets, or gases, and often takes the form of an aerosol (solid particles or liquid droplets dispersed and carried by a gas).^[95] A pollutant can be of natural origin or man-made. Pollutants are classified as primary or secondary. Primary pollutants are usually produced by processes such as ash from a volcanic eruption.

Other examples include carbon monoxide gas from motor vehicle exhausts or sulfur dioxide released from factories. Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact.

Primary pollutants

This section is in prose. You can help by converting this section, if appropriate. Editing help is available. (April 2023)

Pollutants emitted into the atmosphere by human activity include:

• oxides of nitrogen and sulfur to form secondary particles.^[97]
• fossil fuels as an 'air pollutant.'"^[104] CO₂ currently forms about 410 parts per million (ppm) of Earth's atmosphere, compared to about 280 ppm in pre-industrial times,^[105] and billions of metric tons of CO₂ are emitted annually by burning of fossil fuels.^[106] CO₂ increase in Earth's atmosphere has been accelerating.^[107] CO₂ is an asphyxiant gas and not classified as toxic or harmful in general.^[108] Workplace exposure limits exist in places like UK (5,000 ppm for long-term exposure and 15,000 ppm for short-term exposure).^[100] Natural disasters like the limnic eruption at Lake Nyos can result in a sudden release of huge amount of CO₂ as well.^[109]
• Carbon monoxide (CO): CO is a colorless, odorless, toxic gas.^[110] It is a product of combustion of fuel such as natural gas, coal or wood. Vehicular exhaust contributes to the majority of carbon monoxide let into the atmosphere. It creates a smog type formation in the air that has been linked to many lung diseases and disruptions to the natural environment and animals.
• Chlorofluorocarbons (CFCs): Emitted from goods that are now prohibited from use; harmful to the ozone layer. These are gases emitted by air conditioners, freezers, aerosol sprays, and other similar devices. CFCs reach the stratosphere after being released into the atmosphere.^[111] They interact with other gases here, causing harm to the ozone layer. UV rays are able to reach the Earth's surface as a result of this. This can result in skin cancer, eye problems, and even plant damage.^[112]
• plume
  downwind of cities. Nitrogen dioxide is a chemical compound with the formula NO₂. It is one of several nitrogen oxides. One of the most prominent air pollutants, this reddish-brown toxic gas has a characteristic sharp, biting odor.
• Odors: Such as from garbage, sewage, and industrial processes.
• Particulate matter/particles (PM), also known as particulates, atmospheric particulate matter (APM), or fine particles, are microscopic solid or liquid particles suspended in a gas.^[113] Aerosol is a mixture of particles and gas. Volcanoes, dust storms, forest and grassland fires, living plants, and sea spray are all sources of particles. Aerosols are produced by human activities such as the combustion of fossil fuels in automobiles, power plants, and numerous industrial processes.^[114] Averaged worldwide, anthropogenic aerosols – those made by human activities – currently account for approximately 10% of the atmosphere. Increased levels of fine particles in the air are linked to health hazards such as heart disease,^[115] altered lung function and lung cancer. Particulates are related to respiratory infections and can be particularly harmful to those with conditions like asthma.^[116]
• bioaccumulate in human and animal tissue, biomagnify in food chains, and pose a major threat to human health and the ecosystem.^[117]
• Persistent free radicals connected to airborne fine particles are linked to cardiopulmonary disease.^[118][119]
• Polycyclic Aromatic Hydrocarbons (PAHs): a group of aromatic compounds formed from the incomplete combustion of organic compounds including coal and oil and tobacco.^[120]
• nuclear explosions
  , nuclear events, war explosives, and natural processes such as the radioactive decay of radon.
• Sulfur oxides (SO_x): particularly sulfur dioxide, a chemical compound with the formula SO₂. SO₂ is produced by volcanoes and in various industrial processes. Coal and petroleum often contain sulfur compounds, and their combustion generates sulfur dioxide. Further oxidation of SO₂, usually in the presence of a catalyst such as NO₂, forms H₂SO₄, and thus acid rain is formed. This is one of the causes for concern over the environmental impact of the use of these fuels as power sources.
• Toxic metals, such as lead and mercury, especially their compounds.
• global warming. Other hydrocarbon VOCs are also significant greenhouse gases because of their role in creating ozone and prolonging the life of methane in the atmosphere
  . This effect varies depending on local air quality. The aromatic NMVOCs benzene, toluene and xylene are suspected carcinogens and may lead to leukemia with prolonged exposure. 1,3-butadiene is another dangerous compound often associated with industrial use.

• Ground level ozone (O₃): Ozone is created when NOx and VOCs mix. It is a significant part of the troposphere.^[122] It's also an important part of the ozone layer, which can be found in different sections of the stratosphere. Photochemical and chemical reactions involving it fuel many of the chemical activities that occur in the atmosphere during the day and night. It is a pollutant and a component of smog that is produced in large quantities as a result of human activities (mostly the combustion of fossil fuels).^[123]
• Peroxyacetyl nitrate (C₂H₃NO₅): similarly formed from NO_x and VOCs.
• Photochemical smog: particles are formed from gaseous primary contaminants and chemicals.^[124] Smog is a type of pollution that occurs in the atmosphere. Smog is caused by a huge volume of coal being burned in a certain region, resulting in a mixture of smoke and sulfur dioxide.^[125]
  Modern smog is usually caused by automotive and industrial emissions, which are acted on in the atmosphere by UV light from the sun to produce secondary pollutants, which then combine with the primary emissions to generate photochemical smog.

There are many other chemicals classed as hazardous air pollutants. Some of these are regulated in the USA under the Clean Air Act and in Europe under numerous directives (including the Air "Framework" Directive, 96/62/EC, on ambient air quality assessment and management, Directive 98/24/EC, on risks related to chemical agents at work, and Directive 2004/107/EC covering heavy metals and polycyclic aromatic hydrocarbons in ambient air).^[126][127]

• 
  Before flue-gas desulfurization was installed, the emissions from this power plant in New Mexico contained excessive amounts of sulfur dioxide.
• 
  volatile organic compounds

  (VOCs), and odorous emissions.
• This video provides an overview of a NASA study on the human fingerprint on global air quality.

Exposure

The risk of air pollution is determined by the pollutant's hazard and the amount of exposure to that pollutant. Air pollution exposure can be measured for a person, a group, such as a neighborhood or a country's children, or an entire population. For example, one would want to determine a geographic area's exposure to a dangerous air pollution, taking into account the various microenvironments and age groups. This can be calculated^[128] as an inhalation exposure. This would account for daily exposure in various settings, e.g. different indoor micro-environments and outdoor locations. The exposure needs to include different ages and other demographic groups, especially infants, children, pregnant women, and other sensitive subpopulations.^[128]

For each specific time that the subgroup is in the setting and engaged in particular activities, the exposure to an air pollutant must integrate the concentrations of the air pollutant with regard to the time spent in each setting and the respective inhalation rates for each subgroup, playing, cooking, reading, working, spending time in traffic, etc. A little child's inhaling rate, for example, will be lower than that of an adult. A young person engaging in strenuous exercise will have a faster rate of breathing than a child engaged in sedentary activity. The daily exposure must therefore include the amount of time spent in each micro-environmental setting as well as the kind of activities performed there. The air pollutant concentration in each microactivity/microenvironmental setting is summed to indicate the exposure.^[128]

For some pollutants such as black carbon, traffic related exposures may dominate total exposure despite short exposure times since high concentrations coincide with proximity to major roads or participation in (motorized) traffic.^[129] A large portion of total daily exposure occurs as short peaks of high concentrations, but it remains unclear how to define peaks and determine their frequency and health impact.^[130]

In 2021, the WHO halved its recommended guideline limit for tiny particles from burning fossil fuels. The new limit for nitrogen dioxide (NO₂) is 75% lower.^[131] Growing evidence that air pollution—even when experienced at very low levels—hurts human health, led the WHO to revise its guideline (from 10 μg/m³ to 5 μg/m³) for what it considers a safe level of exposure of particulate pollution, bringing most of the world—97.3 percent of the global population—into the unsafe zone.^[132]

Indoor air quality

A lack of ventilation indoors concentrates air pollution where people often spend the majority of their time. Radon (Rn) gas, a carcinogen, is exuded from the Earth in certain locations and trapped inside houses. Building materials including carpeting and plywood emit formaldehyde (H-CHO) gas. Paint and solvents give off volatile organic compounds (VOCs) as they dry. Lead paint can degenerate into dust and be inhaled.^[133][134]

Intentional air pollution is introduced with the use of air fresheners, incense, and other scented items. Controlled wood fires in cook stoves and fireplaces can add significant amounts of harmful smoke particulates into the air, inside and out.^[133][134] Indoor pollution fatalities may be caused by using pesticides and other chemical sprays indoors without proper ventilation. Also the kitchen in a modern produce harmful particles and gases, with equipment like toasters being one of the worst sources.^[135]

Carbon monoxide poisoning and fatalities are often caused by faulty vents and chimneys, or by the burning of charcoal indoors or in a confined space, such as a tent.^[136] Chronic carbon monoxide poisoning can result even from poorly-adjusted pilot lights. Traps are built into all domestic plumbing to keep sewer gas and hydrogen sulfide, out of interiors. Clothing emits tetrachloroethylene, or other dry cleaning fluids, for days after dry cleaning.

Though its use has now been banned in many countries, the extensive use of

The human health effects of poor air quality are far reaching, but principally affect the body's respiratory system and the cardiovascular system. Individual reactions to air pollutants depend on the type of pollutant a person is exposed to, the degree of exposure, and the individual's health status and genetics.[128] The most common sources of air pollution include particulates, ozone, nitrogen dioxide, and sulfur dioxide. Children aged less than five years who live in developing countries are the most vulnerable population in terms of total deaths attributable to indoor and outdoor air pollution.^[141] Under the Clean Air Act, U.S. EPA sets limits on certain air pollutants, including setting limits on how much can be in the air anywhere in the United States.^[142] New research demonstrates that the biological and health outcomes of mixed exposures (Example PM + Ozone) could be significantly greater than individual exposures.^[143]

Air pollution has both acute and chronic effects on human health, affecting a number of different systems and organs. It ranges from minor upper respiratory irritation to chronic respiratory and heart disease, lung cancer, acute respiratory infections in children and chronic bronchitis in adults, aggravating pre-existing heart and lung disease, or asthmatic attacks. Short and long term exposures have been linked with premature mortality and reduced life expectancy.^[144] Diseases that develop from persistent exposure to air pollution are environmental health diseases, which develop when a health environment is not maintained.^[145]

Mortality

Deaths caused by accidents and air pollution from fossil fuel use in power plants exceed those caused by production of renewable energy.^[146]

The share of total deaths from outdoor air pollution, by nation

The World Health Organization estimated in 2014 that every year air pollution causes the premature death of some 7 million people worldwide.^[5] Studies published in March 2019 indicated that the number may be around 8.8 million.^[147] A 2022 review concluded that air pollution was responsible for 6.67 (5.90–7.49) million premature deaths in 2019. It concluded that since 2015 little real progress against (superordinate) pollution, which remained at ~9 million earlier deaths, can be identified.^[148][14] Causes of deaths include strokes, heart disease, COPD, lung cancer, and lung infections.^[5]

Urban outdoor air pollution is estimated to cause 1.3 million deaths worldwide per year.^[149] Children are particularly at risk due to the immaturity of their respiratory organ systems.^[150] In 2015, outdoor air pollution, mostly by PM_2.5, was estimated to lead to 3.3 (95% CI 1.61–4.81) million premature deaths per year worldwide, predominantly in Asia.^[79] In 2021, the WHO reported that outdoor air pollution was estimated to cause 4.2 million premature deaths worldwide in 2016.^[151]

A 2020 study indicates that the global mean loss of life expectancy (LLE; similar to YPLL) from air pollution in 2015 was 2.9 years, substantially more than, for example, 0.3 years from all forms of direct violence, albeit a significant fraction of the LLE is unavoidable.^[16] Communities with the most exceptional aging have low ambient air pollution, suggesting a link between air pollution levels and longevity.^[152]

A study published in 2022 in GeoHealth concluded that eliminating energy-related fossil fuel emissions in the United States would prevent 46,900–59,400 premature deaths each year and provide $537–$678 billion in benefits from avoided PM_2.5-related illness and death.^[153] A study published in 2023 in Science focused on sulfur dioxide emissions by coal power plants (coal PM_2.5) and concluded that "exposure to coal PM_2.5 was associated with 2.1 times greater mortality risk than exposure to PM_2.5 from all sources."^[154] From 1999 to 2020, a total of 460,000 deaths in the US were attributed to coal PM_2.5.^[154]

By region

India and China have the highest death rate due to air pollution.^[155][156] India also has more deaths from asthma than any other nation according to the World Health Organization. In 2019, 1.6 million deaths in India were caused by air pollution.^[157] In December 2013, air pollution was estimated to kill 500,000 people in China each year.^[158] There is a positive correlation between pneumonia-related deaths and air pollution from motor vehicle emissions.^[159]

Annual premature European deaths caused by air pollution are estimated at 430,000^[160] to 800,000.^[147] An important cause of these deaths is nitrogen dioxide and other nitrogen oxides (NOx) emitted by road vehicles.^[160] In a 2015 consultation document the UK government disclosed that nitrogen dioxide is responsible for 23,500 premature UK deaths per annum.^[161] Across the European Union, air pollution is estimated to reduce life expectancy by almost nine months.^[162]

Guidelines

The US EPA has estimated that limiting ground-level ozone concentration to 65 parts per billion (ppb), would avert 1,700 to 5,100 premature deaths nationwide in 2020 compared with the 75 ppb standard. The agency projected the more protective standard would also prevent an additional 26,000 cases of aggravated asthma, and more than a million cases of missed work or school.^[163][164] Following this assessment, the EPA acted to protect public health by lowering the National Ambient Air Quality Standards (NAAQS) for ground-level ozone to 70 ppb.^[165]

A 2008 economic study of the health impacts and associated costs of air pollution in the Los Angeles Basin and San Joaquin Valley of Southern California shows that more than 3,800 people die prematurely (approximately 14 years earlier than normal) each year because air pollution levels violate federal standards. The number of annual premature deaths is considerably higher than the fatalities related to auto collisions in the same area, which average fewer than 2,000 per year.^{[166][167][168]} A 2021 study found that outdoor air pollution is associated with substantially increased mortality "even at low pollution levels below the current European and North American standards and WHO guideline values" shortly before the WHO adjusted its guidelines.^[169][170]

Major causes

The largest cause is air pollution generated by fossil fuel combustion^[172] – mostly the production and use of cars, electricity production, and heating.^[173] A study by Greenpeace estimates there are 4.5 million annual premature deaths worldwide because of pollutants released by high-emission power stations and vehicle exhausts.^[174]

Diesel exhaust (DE) is a major contributor to combustion-derived particulate matter air pollution. In several human experimental studies, using a well-validated exposure chamber setup, DE has been linked to acute vascular dysfunction and increased thrombus formation.^[175][176]

A study concluded that PM_2.5 air pollution induced by the contemporary free trade and consumption by the 19 G20 nations causes two million premature deaths annually, suggesting that the average lifetime consumption of about ~28 people in these countries causes at least one premature death (average age ~67) while developing countries "cannot be expected" to implement or be able to implement countermeasures without external support or internationally coordinated efforts.^[177][171]

Primary mechanisms

The WHO estimates that in 2016, ~58% of outdoor air pollution-related premature deaths were due to ischaemic heart disease and stroke.^[151] The mechanisms linking air pollution to increased cardiovascular mortality are uncertain, but probably include pulmonary and systemic inflammation.^[178]

Contemporary annual deaths

A 2021 study by scientists of U.K. and U.S. universities that uses a high spatial resolution model and an updated concentration-response function concluded that 10.4 million global excess deaths in 2012 and 8.7 million in 2018 – or a fifth^{[dubious – discuss]} – were due to air pollution generated by fossil fuel combustion, significantly higher than earlier estimates and with spatially subdivided mortality impacts.^[179][172]

According to the WHO, air pollution accounts for 1 in 8 deaths worldwide.^[180]

Cardiovascular disease

According to the Global Burden of Disease Study, air pollution is responsible for 19 percent of all cardiovascular deaths.^[181][182] A 2022 review of over 50 studies carried out between 2010 and 2021 found strong evidence linking both short- and long-term exposure to air pollution with cardiovascular disease mortality and morbidity, stroke, blood pressure, and ischemic heart diseases (IHD).^[182]

Air pollution is a leading risk factor for stroke, particularly in developing countries where pollutant levels are highest.^[183] A systematic analysis of 17 different risk factors in 188 countries found air pollution is associated with nearly one in three strokes (29 percent) worldwide (33.7 percent of strokes in developing countries versus 10.2 percent in developed countries).^[183][184] A 2007 study found that in women, air pollution is not associated with hemorrhagic but with ischemic stroke.^[185] Air pollution was found to be associated with increased incidence and mortality from coronary stroke in a cohort study in 2011.^[186] Associations are believed to be causal and effects may be mediated by vasoconstriction, low-grade inflammation and atherosclerosis.^[187] Other mechanisms such as autonomic nervous system imbalance have also been suggested.^[188][189]

Lung disease

Research has demonstrated increased risk of developing asthma^[190] and chronic obstructive pulmonary disease (COPD)^[191] from increased exposure to traffic-related air pollution. Air pollution has been associated with increased hospitalization and mortality from asthma and COPD.^[192][193] COPD includes diseases such as chronic bronchitis and emphysema.^[194] The risk of lung disease from air pollution is greatest for the following groups of people: infants and young children, whose normal breathing is faster than that of older children and adults; the elderly; those who work outside or spend a lot of time outside; and those who have heart or lung disease.^[195]

A study conducted in 1960–1961 in the wake of the

It is believed that much like cystic fibrosis, by living in a more urban environment serious health hazards become more apparent. Studies have shown that in urban areas people experience mucus hypersecretion, lower levels of lung function, and more self-diagnosis of chronic bronchitis and emphysema.^[199]

COPD comprises a spectrum of clinical disorders that include emphysema, bronchiectasis, and chronic bronchitis. COPD risk factors are both genetic and environmental. Elevated particle pollution contributes to the exacerbation of this disease and likely its pathogenesis.^[200]

Cancer (lung cancer)

Around 300,000 lung cancer deaths were attributed globally in 2019 to exposure to

A review of evidence regarding whether ambient air pollution exposure is a risk factor for cancer in 2007 found solid data to conclude that long-term exposure to PM_2.5 (fine particulates) increases the overall risk of non-accidental mortality by 6% per a 10 μg/m³ increase. Exposure to PM_2.5 was also associated with an increased risk of mortality from lung cancer (range: 15–21% per 10 μg/m³ increase) and total cardiovascular mortality (range: 12–14% per a 10 μg/m³ increase).^[204]

The review further noted that living close to busy traffic appears to be associated with elevated risks of these three outcomes – increase in lung cancer deaths, cardiovascular deaths, and overall non-accidental deaths. The reviewers also found suggestive evidence that exposure to PM_2.5 is positively associated with mortality from coronary heart diseases and exposure to SO₂ increases mortality from lung cancer, but the data was insufficient to provide solid conclusions.^[204] Another investigation showed that higher activity level increases deposition fraction of aerosol particles in human lung and recommended avoiding heavy activities like running in outdoor space at polluted areas.^[205]

In 2011, a large Danish epidemiological study found an increased risk of lung cancer for people who lived in areas with high nitrogen oxide concentrations. In this study, the association was higher for non-smokers than smokers.^[206] An additional Danish study, also in 2011, likewise noted evidence of possible associations between air pollution and other forms of cancer, including cervical cancer and brain cancer.^[207]

A study presented in 2022 outlined the biological basis for how air pollution causes cancer.^[203]

Eye disease

A 2021 study in the UK has suggested a possible association between higher exposure to air pollution and risk of cataract surgery.^[208] This study investigated PM_2.5, nitrogen dioxide (NO₂), and nitrogen oxide (NO_x) exposure, estimated based on land use models, and identified participants undergoing cataract surgery based on National Health Service data.^[208] The authors of this study did note that the relatively low effect estimates and increased risk of 5% indicate a need for further research in determining the existence of a causal relationship.

A prospective study published in 2023 measured the thickness of the retinal nerve fiber layer in participants over a span of 11 years, aiming to identify associations between air pollution and the development of glaucoma.^[209] Air pollution measures used included PM_2.5, NO₂, and black carbon (BC). The researchers concluded that there was a strong association between exposure to PM_2.5 and retinal degeneration, even at air pollution levels below the current European recommended thresholds.^[209] This association and similar results have also been seen in a 2021 case-control study in Taiwan.^[210] In this study, doubling monthly exposure to PM_2.5 increased the risk of developing glaucoma by 66 percent.

Dry eye disease (DED), which has been diagnosed at increasing rates in recent decades, has also been associated with increased air pollution. A 2018 study published in Taiwan measured the ambient temperature, levels of NO₂, and carbon monoxide (CO) of patients experiencing DED.^[211] The researchers found that all of these measures were positively associated with the development of DED at a statistically significant level.^[211]

Another Taiwanese study from 2022 sought to identify the relationship between PM_2.5 and the development of macular degeneration. Using over 4 million participants in a cohort study, and PM_2.5 measurements via satellite, the researchers concluded that participants had a 19 percent increased risk of macular degeneration with just a 10 microgram increase in PM_2.5 exposure.^[212]

A Chinese study published in 2020 identified a significant effect of 10 microgram increases in PM_2.5 exposure on the development of conjunctivitis.^[213] This effect was noted to be acute and most significant at the current day, with effects dropping off after a period of 2 days. The impact was also significantly affected by socioeconomic and demographic factors, leading the authors to also conclude that vulnerable populations are those most at risk.^[213]

Kidney disease

In 2021, a study of 163,197 Taiwanese residents over the period of 2001–2016 estimated that every 5 μg/m³ decrease in the ambient concentration of PM_2.5 was associated with a 25% reduced risk of chronic kidney disease development.^[214] According to a chord study involving 10,997 atherosclerosis patients, higher PM 2.5 exposure is associate with increased albuminuria.^[215]

Fertility

NO₂

In women undergoing

In the general population, there is a significant increase in miscarriage rate in women exposed to NO₂ compared to the non-exposed group.^[216]

CO

CO exposure is significantly associated with stillbirth in the second and third trimester.^[216]

Polycyclic aromatic hydrocarbons

Exposure to BaP has been reported to reduce sperm motility and increasing the exposure worsens this effect. Research has demonstrated that more BaPs were found in men with reported fertility issues compared to men without.^[219]

Studies have shown that BaPs can affect folliculogenesis and ovarian development by reducing the number of ovarian germ cells via triggering cell death pathways and inducing inflammation which can lead to ovarian damage.^[220]

Particulate matter

In a study based in California it was found that as exposure to PM_2.5 increased sperm motility decreased and morphology became more abnormal. Similarly, in Poland exposure to PM_2.5 and PM₁₀ lead to an increase in the percentage of cells with immature chromatin (DNA that has not fully developed or has developed abnormally).^[221]

In Turkey, a study looked at the fertility of men who work as toll collectors and are therefore exposed to high levels of traffic pollutants daily. Traffic pollution often has high levels of PM₁₀ alongside

In women, whilst overall effects on fertility did not seem significant there was an association was found between increased exposure to PM₁₀ and early miscarriage. Exposure to smaller particulate matter, PM_2.5, was seen to have an effect on conception rates in women undergoing IVF but not with live birth rates.^[216]

Ground-level ozone pollution

Ground-level ozone (O₃), when in high concentrations, is regarded as an air pollutant and is often found in smog in industrial areas. O₃ is largely produced by chemical reactions involving NO_x gases (nitrous oxides, especially from combustion) and volatile organic compounds in the presence of sunlight.

There is limited research about the effect that ozone pollution has on fertility.^[216] At present, there is no evidence to suggest that ozone exposure poses a deleterious effect on spontaneous fertility in either females or males. However, there have been studies which suggest that high levels of ozone pollution, often a problem in the summer months, exert an effect on in vitro fertilisation (IVF) outcomes. Within an IVF population, NO_x and ozone pollutants were linked with reduced rates of live birth.^[216]

While most research on this topic is focused on the direct human exposure of air pollution, other studies have analysed the impact of air pollution on gametes and embryos within IVF laboratories. Multiple studies have reported a marked improvement in embryo quality, implantation and pregnancy rates after IVF laboratories have implemented air filters in a concerted effort to reduce levels of air pollution.^[222] Therefore, ozone pollution is considered to have a negative impact on the success of assisted reproductive technologies (ART) when occurring at high levels.

Ozone is thought to act in a biphasic manner where a positive effect on live birth is observed when ozone exposure is limited to before IVF embryo implantation.^[223] Conversely, a negative effect is demonstrated upon exposure to ozone after embryo implantation.^[224]

Retrospective and prospective studies evaluating the effect of several traffic pollutants (of which ground-level ozone is one) highlighted a significant decrease in live birth rates and miscarriages.^[222]

In terms of male fertility, ozone is reported to cause a significant decrease in sperm concentration measured in semen after exposure.^[225] Similarly, sperm vitality, the proportion of alive spermatozoa in a sample, was demonstrated to be diminished in a handful of studies.^[224] This demonstrates that ozone air pollution exhibits a significantly negative effect of air pollution on this parameter. However, findings on the effect of ozone exposure on male fertility are somewhat discordant, highlighting the need for further research.^[224]

Children

In the United States, despite the passage of the Clean Air Act in 1970, in 2002 at least 146 million Americans were living in

Researchers have begun to find evidence for air pollution as a risk factor for autism spectrum disorder (ASD). In Los Angeles, children who were living in areas with high levels of traffic-related air pollution were more likely to be diagnosed with autism between three–five years of age.^[232] The connection between air pollution and neurodevelopmental disorders in children is thought to be related to epigenetic dysregulation of the primordial germ cells, embryo, and fetus during a critical period. Some PAHs are considered endocrine disruptors and are lipid soluble. When they build up in adipose tissue, they can be transferred across the placenta.^[233] Air pollution has been associated with the prevalence of preterm births.^[234]

Infants

Ambient levels of air pollution have been associated with preterm birth and low birth weight. A 2014 WHO worldwide survey on maternal and perinatal health found a statistically significant association between low birth weights (LBW) and increased levels of exposure to PM_2.5. Women in regions with greater than average PM_2.5 levels had statistically significant higher odds of pregnancy resulting in a low-birth weight infant even when adjusted for country-related variables.^[235] The effect is thought to be from stimulating inflammation and increasing oxidative stress.

A study by the University of York found that in 2010 exposure to PM_2.5 was strongly associated with 18% of preterm births globally, which was approximately 2.7 million premature births. The countries with the highest air pollution associated preterm births were in South and East Asia, the Middle East, North Africa, and West sub-Saharan Africa.^[236] In 2019, ambient particulate matter pollution in Africa resulted in at least 383,000 early deaths, according to new estimates of the cost of air pollution in the continent. This increased from 3.6% in 1990 to around 7.4% of all premature deaths in the area.^{[237][238][239]}

The source of PM_2.5 differs greatly by region. In South and East Asia, pregnant women are frequently exposed to indoor air pollution because of wood and other biomass fuels being used for cooking, which are responsible for more than 80% of regional pollution. In the Middle East, North Africa and West sub-Saharan Africa, fine PM comes from natural sources, such as dust storms.^[236] The United States had an estimated 50,000 preterm births associated with exposure to PM_2.5 in 2010.^[236]

A study between 1988 and 1991 found a correlation between sulfur dioxide (SO₂) and total suspended particulates (TSP) and preterm births and low birth weights in Beijing. A group of 74,671 pregnant women, in four separate regions of Beijing, were monitored from early pregnancy to delivery along with daily air pollution levels of sulfur Dioxide and TSP (along with other particulates). The estimated reduction in birth weight was 7.3 g for every 100 μg/m³ increase in SO₂ and 6.9 g for each 100 μg/m³ increase in TSP. These associations were statistically significant in both summer and winter, although, summer was greater. The proportion of low birth weight attributable to air pollution, was 13%. This is the largest attributable risk ever reported for the known risk factors of low birth weight.^[240] Coal stoves, which are in 97% of homes, are a major source of air pollution in this area.

Brauer et al. studied the relationship between air pollution and proximity to a highway with pregnancy outcomes in a Vancouver cohort of pregnant woman using addresses to estimate exposure during pregnancy. Exposure to NO, NO₂, CO, PM₁₀ and PM_2.5 were associated with infants born small for gestational age (SGA). Women living less than 50 meters away from an expressway or highway were 26% more likely to give birth to a SGA infant.^[241]

"Clean" areas

Even in areas with relatively low levels of air pollution, public health effects can be significant and costly, since a large number of people breathe in such pollutants. A study published in 2017 found that even in areas of the U.S. where ozone and PM_2.5 meet federal standards, Medicare recipients who are exposed to more air pollution have higher mortality rates.^[242]

A 2005 scientific study for the British Columbia Lung Association showed that a small improvement in air quality (1% reduction of ambient PM_2.5 and ozone concentrations) would produce $29 million in annual savings in the Metro Vancouver region in 2010.^[243] This finding is based on health valuation of lethal (death) and sub-lethal (illness) affects. A study published in 2022 found that rural population in India, like those in urban areas, are also exposed to high levels of air pollution.^[244]

In 2020, scientists found that the boundary layer air over the Southern Ocean around Antarctica is 'unpolluted' by humans.^[245]

Central nervous system

Data is accumulating that air pollution exposure also affects the central nervous system.^[246]

Air pollution increases the risk of dementia in people over 50 years old.

Exposure to fine particulate matter can increase levels of cytokines - neurotransmitters produced in response to infection and inflammation that are also associated with depression and suicide. Pollution has been associated with inflammation of the brain, which may disrupt mood regulation. According to a study of Washington DC's American University, heightened PM_2.5 levels are linked to more self-reported depressive symptoms, and increases in daily suicide rates.^[252]

In a study of mice, air pollution also has a larger negative impact on males than on females.^{[253][254][255]}

In 2015, experimental studies reported the detection of significant episodic (situational) cognitive impairment from impurities in indoor air breathed by test subjects who were not informed about changes in the air quality. Researchers at the

Various studies have estimated the impacts of air pollution on agriculture, especially ozone. A 2020 study showed that ozone pollution in California may reduce yields of certain perennial crops such as table grapes by as much as 22% per year, translating into economic damages of more than $1 billion per year.[259] After air pollutants enter the agricultural environment, they not only directly affect agricultural production and quality, but also enter agricultural waters and soil.^[260] The COVID-19 induced lockdown served as a natural experiment to expose the close links between air quality and surface greenness. In India, the lockdown induced improvement in air quality, enhanced surface greenness and photosynthetic activity, with the positive response of vegetation to reduce air pollution was dominant in croplands.^[261] On the other hand, agriculture in its traditional form is one of the primary contributors to the emission of trace gases like atmospheric ammonia.^[262]

Economic effects

Air pollution costs the

Artificial air pollution may be detectable on Earth from distant vantage points such as other planetary systems via atmospheric SETI – including NO₂ pollution levels and with telescopic technology close to today. It may also be possible to detect extraterrestrial civilizations this way.^{[265][266][267]}

Historical disasters

The world's worst short-term civilian pollution crisis was the 1984

An accidental leak of anthrax spores from a biological warfare laboratory in the former USSR in 1979 near Yekaterinburg (formerly Sverdlovsk) is believed to have caused at least 64 deaths.^[270] The worst single incident of air pollution to occur in the US occurred in Donora, Pennsylvania, in late October 1948, when 20 people died and over 7,000 were injured.^[271]

Reduction and regulation

Global depletion of the surrounding air pollution will require valiant leadership, a surplus of combined resources from the international community, and extensive societal changes.

Efforts to reduce particulate matter in the air may result in better health.[276]

The 9-Euro-Ticket scheme in Germany which allowed people to buy a monthly pass allowing use on all local and regional transport (trains, trams and busses) for 9 euro (€) for one month of unlimited travel saved 1.8 million tons of CO₂ emissions during its three-month implementation from June to August 2022.^[277]

Pollution control

Various pollution control technologies and strategies are available to reduce air pollution.^[278][279] At its most basic level, land-use planning is likely to involve zoning and transport infrastructure planning. In most developed countries, land-use planning is an important part of social policy, ensuring that land is used efficiently for the benefit of the wider economy and population, as well as to protect the environment.^[280] Stringent environmental regulations, effective control technologies and shift towards the renewable source of energy also helping countries like China and India to reduce their sulfur dioxide pollution.^[281]

Titanium dioxide has been researched for its ability to reduce air pollution. Ultraviolet light will release free electrons from material, thereby creating free radicals, which break up VOCs and NO_x gases. One form is superhydrophilic.^[282]

Pollution-eating nanoparticles placed near a busy road were shown to absorb toxic emission from around 20 cars each day.^[283]

Energy transition

Since a large share of air pollution is caused by combustion of fossil fuels such as coal and oil, the reduction of these fuels can reduce air pollution drastically. Most effective is the switch to clean power sources such as

There are now practical alternatives to the principal causes of air pollution:

• Strategic substitution of air pollution sources in transport with lower-emission or, during the lifecycle, emission-free forms of
  bicycle use and infrastructure (as well as with remote work, reductions of work, relocations, and localizations
  )
  • Phase-out of fossil fuel vehicles is a critical component of a shift to sustainable transport; however, similar infrastructure and design decisions like electric vehicles may be associated with similar pollution for production as well as mining and resource exploitation for large numbers of needed batteries as well as the energy for their recharging^[287][288]
• Areas downwind (over 20 miles) of major airports have more than double total particulate emissions in air than other areas, even when factoring in areas with frequent ship calls, and heavy freeway and city traffic like Los Angeles.^[289] Aviation biofuel mixed in with jetfuel at a 50/50 ratio can reduce jet derived cruise altitude particulate emissions by 50–70%, according to a NASA led 2017 study (however, this should imply ground level benefits to urban air pollution as well).^[290]
• Ship propulsion and idling can be switched to much cleaner fuels like natural gas. (Ideally a renewable source but not practical yet)
• Combustion of fossil fuels for space heating can be replaced by using
  ground source heat pumps and seasonal thermal energy storage.^[291]
• Electricity generated from the combustion of fossil fuels can be replaced by nuclear and renewable energy. Heating and home stoves, which contribute significantly to regional air pollution, can be replaced with a much cleaner fossil fuel, such as natural gas, or, preferably, renewables, in poor countries.[292]^[293]
• Motor vehicles driven by fossil fuels, a key factor in urban air pollution, can be replaced by electric vehicles. Though lithium supply and cost is a limitation, there are alternatives. Herding more people into clean public transit such as electric trains can also help. Nevertheless, even in emission-free electric vehicles, rubber tires produce significant amounts of air pollution themselves, ranking as 13th worst pollutant in Los Angeles.^[294]
• Reducing travel in vehicles can curb pollution. After Stockholm reduced vehicle traffic in the central city with a congestion tax, nitrogen dioxide and PM₁₀ pollution declined, as did acute pediatric asthma attacks.^[295]
• slash and burn is prevalent, turning a useless commodity into a source of income. The plants can be gathered and sold to a central authority that will break them down in a large modern biodigester, producing much needed energy to use.^[296]
• Induced humidity and ventilation both can greatly dampen air pollution in enclosed spaces, which was found to be relatively high inside subway lines due to braking and friction and relatively less ironically inside transit buses than lower sitting passenger automobiles or subways.[297]

Control devices

The following items are commonly used as pollution control devices in industry and transportation. They can either destroy contaminants or remove them from an exhaust stream before it is emitted into the atmosphere.

Monitoring

Spatiotemporal monitoring of air quality may be necessary for improving air quality, and thereby the health and safety of the public, and assessing impacts of interventions.^[298] Such monitoring is done to different extents with different regulatory requirements with discrepant regional coverage by a variety of organizations and governance entities such as using a variety of technologies for use of the data and sensing such mobile IoT sensors,^[299][300] satellites,^{[301][302][303]} and monitoring stations.^[304][305] Some websites attempt to map air pollution levels using available data.^{[306][307][308]}

Air quality modeling

Numerical models either on a global scale using tools such as GCMs (general circulation models coupled with a pollution module) or CTMs (Chemical transport model) can be used to simulate the levels of different pollutants in the atmosphere. These tools can have several types (Atmospheric model) and different uses. These models can be used in forecast mode which can help policy makers to decide on appropriate actions when an air pollution episode is detected. They can also be used for climate modeling including evolution of air quality in the future, for example the IPCC (Intergovernmental Panel on Climate Change) provides climate simulations including air quality assessments in their reports (latest report accessible through their site).

Regulations

In general, there are two types of air quality standards. The first class of standards (such as the U.S. National Ambient Air Quality Standards and E.U. Air Quality Directive^[309]) set maximum atmospheric concentrations for specific pollutants. Environmental agencies enact regulations which are intended to result in attainment of these target levels. The second class (such as the North American air quality index) take the form of a scale with various thresholds, which is used to communicate to the public the relative risk of outdoor activity. The scale may or may not distinguish between different pollutants.

Canada

In Canada, air pollution and associated health risks are measured with the Air Quality Health Index (AQHI).^[310] It is a health protection tool used to make decisions to reduce short-term exposure to air pollution by adjusting activity levels during increased levels of air pollution.

The AQHI is a federal program jointly coordinated by

As it is now known that even low levels of air pollution can trigger discomfort for the sensitive population, the index has been developed as a continuum: The higher the number, the greater the health risk and need to take precautions. The index describes the level of health risk associated with this number as 'low', 'moderate', 'high' or 'very high', and suggests steps that can be taken to reduce exposure.[311]

The measurement is based on the observed relationship of nitrogen dioxide (NO₂), ground-level ozone (O₃) and particulates (PM_2.5) with mortality, from an analysis of several Canadian cities. Significantly, all three of these pollutants can pose health risks, even at low levels of exposure, especially among those with pre-existing health problems.

When developing the AQHI, Health Canada's original analysis of health effects included five major air pollutants: particulates, ozone, and nitrogen dioxide (NO₂), as well as sulfur dioxide (SO₂), and carbon monoxide (CO). The latter two pollutants provided little information in predicting health effects and were removed from the AQHI formulation.

The AQHI does not measure the effects of odour, pollen, dust, heat or humidity.

Germany

TA Luft is the German air quality regulation.^[313]

Governing urban air pollution

In Europe, Council Directive 96/62/EC on ambient air quality assessment and management provides a common strategy against which

In July 2008, in the case Dieter Janecek v. Freistaat Bayern, the European Court of Justice ruled that under this directive^[314] citizens have the right to require national authorities to implement a short term action plan that aims to maintain or achieve compliance to air quality limit values.^[315][316]

This important case law appears to confirm the role of the EC as centralised regulator to European nation-states as regards air pollution control. It places a supranational legal obligation on the UK to protect its citizens from dangerous levels of air pollution, furthermore superseding national interests with those of the citizen.

In 2010, the

In response to these charges, mayor of London Boris Johnson has criticised the current need for European cities to communicate with Europe through their nation state's central government, arguing that in future "A great city like London" should be permitted to bypass its government and deal directly with the European Commission regarding its air quality action plan.^[319]

This can be interpreted as recognition that cities can transcend the traditional national government organisational hierarchy and develop solutions to air pollution using global governance networks, for example through transnational relations. Transnational relations include but are not exclusive to national governments and intergovernmental organisations,^[322] allowing sub-national actors including cities and regions to partake in air pollution control as independent actors.

Global city partnerships can be built into networks, for example the C40 Cities Climate Leadership Group, of which London is a member. The C40 is a public 'non-state' network of the world's leading cities that aims to curb their greenhouse emissions.^[323] The C40 has been identified as 'governance from the middle' and is an alternative to intergovernmental policy.^[324] It has the potential to improve urban air quality as participating cities "exchange information, learn from best practices and consequently mitigate carbon dioxide emissions independently from national government decisions".^[323] A criticism of the C40 network is that its exclusive nature limits influence to participating cities and risks drawing resources away from less powerful city and regional actors.

Indigenous people

Because Indigenous people^[325] frequently experience a disproportionate share of the effects of environmental degradation and climate change, even while they have made very little contribution to the processes causing these changes, environmental justice is especially important to them. Indigenous peoples have been marginalized and their lands and resources have been exploited as a result of historical and continuing colonization, institutional injustices, and inequality.

Indigenous groups frequently lack the political and financial clout to influence policy decisions that impact their lands and means of subsistence or to lessen the effects of climate change. This makes the already-existing inequalities in these communities' social, economic, and health conditions worse. Furthermore, traditional ecological knowledge and Indigenous knowledge systems provide insightful information about sustainable resource management and climate change adaptation techniques. To promote persistence and environmental justice, Indigenous viewpoints must be acknowledged and integrated into efforts to mitigate the effects of climate change and adapt to them.

Combating climate change necessitates an all-encompassing strategy that recognizes the interdependence of social, economic, and environmental elements. This entails defending treaty rights, advancing Indigenous sovereignty and self-determination, and aiding Indigenous-led projects for sustainable development and environmental preservation.

Hotspots

Air pollution hotspots are areas where air pollution emissions expose individuals to increased negative health effects.[326] They are particularly common in highly populated, urban areas, where there may be a combination of stationary sources (e.g. industrial facilities) and mobile sources (e.g. cars and trucks) of pollution. Emissions from these sources can cause respiratory disease, childhood asthma,^[140] cancer, and other health problems. Fine particulate matter such as diesel soot, which contributes to more than 3.2 million premature deaths around the world each year, is a significant problem. It is very small and can lodge itself within the lungs and enter the bloodstream. Diesel soot is concentrated in densely populated areas, and one in six people in the U.S. live near a diesel pollution hot spot.^[327]

External videos
AirVisual Earth – realtime map of global wind and air pollution[328]

While air pollution hotspots affect a variety of populations, some groups are more likely to be located in hotspots. Previous studies have shown disparities in exposure to pollution by race and/or income.

Air pollution is usually concentrated in densely populated metropolitan areas, especially in developing countries where cities are experiencing rapid growth and environmental regulations are relatively lax or nonexistent. Urbanization leads to a rapid rise in premature mortality due to anthropogenic air pollution in fast-growing tropical cities.^[333] However, even populated areas in developed countries attain unhealthy levels of pollution, with Los Angeles and Rome being two examples.^[334] Between 2002 and 2011 the incidence of lung cancer in Beijing near doubled. While smoking remains the leading cause of lung cancer in China, the number of smokers is falling while lung cancer rates are rising .^[335]

Tehran was declared the most polluted city in the world on May 24, 2022.^[337]

Projections

In a 2019 projection, by 2030 half of the world's pollution emissions could be generated by Africa.^[338] Potential contributors to such an outcome include increased burning activities (such as the burning of open waste), traffic, agri-food and chemical industries, sand dust from the Sahara, and overall population growth.

In a 2012 study, by 2050 outdoor air pollution (particulate matter and ground-level ozone) is projected to become the top cause of environmentally related deaths worldwide.^[339]

See also

References

Further reading

Library resources about
Air pollution

---

• Resources in your library
• Resources in other libraries

• ISBN 978-1-136-70329-4
  .
• OCLC 43084000
  .
• doi:10.1504/ijep.2005.007599
  .
• Cherni, Judith A. Economic Growth versus the Environment: The Politics of Wealth, Health and Air Pollution (2002) online
• Corton, Christine L. London Fog: The Biography (2015)
• Currie, Donya. "WHO: Air Pollution a Continuing Health Threat in World's Cities", The Nation's Health (February 2012) 42#1 online
• Dewey, Scott Hamilton. Don't Breathe the Air: Air Pollution and US Environmental Politics, 1945–1970 (Texas A & M University Press, 2000)
• Gonzalez, George A. The politics of air pollution: Urban growth, ecological modernization, and symbolic inclusion (SUNY Press, 2012)
• Grinder RD (1978). "From Insurgency to Efficiency: The Smoke Abatement Campaign in Pittsburgh before World War I.". Western Pennsylvania Historical Magazine. 61 (3): 187–202.
• Grinder, Robert Dale. "The Battle for Clean Air: The Smoke Problem in Post-Civil War America" in Martin V. Melosi, ed., Pollution & Reform in American Cities, 1870–1930 (1980), pp. 83–103.
• Kumar P, Pirjola L, Ketzel M, Harrison RM (2013). "Nanoparticle emissions from 11 non-vehicle exhaust sources – A review". Atmospheric Environment. 67. Elsevier BV: 252–277.
  ISSN 1352-2310
  .
• Lundqvist LJ (1980). The Hare and the Tortoise: Clean Air Policy in the US and Sweden. Ann Arbor, MI: University of Michigan Press.
  ISBN 978-0-472-09310-6
  .
• Mingle, Jonathan, "Our Lethal Air" [review of Gary Fuller, The Invisible Killer...; Beth Gardiner, Choked...; Tim Smedley, Clearing the Air...;
  heart attacks. [T]hey exacerbate respiratory illnesses like asthma and chronic obstructive pulmonary disease ... There's ... evidence linking air pollution exposure to an increased risk of Alzheimer's and other forms of dementia
  ." (p. 64.)
• Mosley, Stephen. The chimney of the world: a history of smoke pollution in Victorian and Edwardian Manchester. Routledge, 2013.
• Schreurs, Miranda A. Environmental Politics in Japan, Germany, and the United States (Cambridge University Press, 2002) online
• Thorsheim, Peter. Inventing Pollution: Coal, Smoke, and Culture in Britain since 1800 (2009)

External links

Wikimedia Commons has media related to Air pollution.

Wikivoyage has travel information for Air pollution.

• WHO fact sheet on outdoor air pollution
• Air Pollution: Everything You Need to Know Guide by the Natural Resources Defense Council (NRDC)
• Global real-time air quality index map
• Air Quality Index (AQI) Basics
• AQI Calculator AQI to Concentration and Concentration to AQI for five pollutants
• UNEP Urban environmental planning
• European Commission > Environment > Air > Air Quality
• Database: outdoor air pollution in cities from the World Health Organization
• The Mortality Effects of Long-Term Exposure to Particulate Air Pollution in the United Kingdom, UK Committee on the Medical Effects of Air Pollution, 2010.
• Hazardous air pollutants | What are hazardous pollutants at EPA.gov