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Air pollution is the presence of substances in the
atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet or other material body, that is held in ...

atmosphere
that are harmful to the
health Health, according to the World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations United Nations Specialized Agencies are autonomous organizations working with the United Nations and each ...

health
of
human Humans (''Homo sapiens'') are the most abundant and widespread species In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes ...

human
s and other
living beings Life form (also spelled life-form or lifeform) is an wikt:entity, entity that is Life, living, such as plants (flora) and animals (fauna). It is estimated that more than 99% of all species that ever existed on Earth, amounting to over five billio ...
, or cause damage to the
climate Climate is the long-term pattern of weather Weather is the state of the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a la ...

climate
or to materials. There are different types of air pollutants, such as gases (such as
ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...

ammonia
,
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom. It is the simplest molecule of the oxocarbon family. In ...

carbon monoxide
,
sulfur dioxide Sulfur dioxide (-recommended spelling) or sulphur dioxide (traditional ) is the with the formula . It is a responsible for the smell of burnt es. It is released naturally by and is produced as a by-product of extraction and the burning of ...
,
nitrous oxides
nitrous oxides
,
methane Methane (, ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth ...
and
chlorofluorocarbons Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain only (C), (H), (Cl), and (F), produced as derivatives of , , and . They are also commonly known by the brand name . ...
),
particulates Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM), or suspended particulate matter (SPM) – are microscopic The microscopic scale (from , ''mikrós'', "small" and σκοπ ...
(both organic and inorganic), and biological molecules. Air pollution may cause diseases, allergies and even death to humans; it may also cause harm to other living organisms such as animals and food crops, and may damage the
natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, universus) is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and ...

natural
environment (for example,
climate change Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known even ...
,
ozone depletion Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth, Earth's atmosphere (the ozone layer), and a much larger springtime decrease in stratosphe ...

ozone depletion
or
habitat degradation Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
) or
built environment In urban planning Urban planning, also known as regional planning, town planning, city planning, or rural planning, is a technical and political process that is focused on the development and design of land use and the built environment, in ...
(for example,
acid rain Acid rain is a rain or any other form of Precipitation (meteorology), precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals, and infras ...
). Both human activity and natural processes can generate air pollution. Air pollution is a significant
risk factor In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted wiktionary:determine, scientific m ...
for a number of pollution-related diseases, including
respiratory infection Respiratory tract infections (RTIs) are infectious diseases involving the respiratory tract. An infection of this type usually is further classified as an upper respiratory tract infection (URI or URTI) or a lower respiratory tract infection (LRI o ...
s,
heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped b ...
,
COPD Chronic obstructive pulmonary disease (COPD) is a type of obstructive lung disease characterized by long-term breathing problems and poor airflow. The main symptoms include shortness of breath and cough with sputum production. COPD is a pro ...
,
stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Di ...

stroke
and
lung cancer Lung cancer, also known as lung carcinoma, since about 98–99% of all lung cancers are carcinomas, is a malignant lung tumor ''Lung tumors'' are neoplastic lung nodules. These include: Primary tumorA primary tumor is a tumor A neoplas ...

lung cancer
. The human health effects of
poor air quality Poverty is the state of not having enough material possessions or income for a person's basic needs. Poverty may include social, economic, and political elements. ''Absolute poverty'' is the complete lack of the means necessary to meet basic pe ...

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. Indoor air pollution and poor urban air quality are listed as two of the world's worst
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous s ...

toxic
pollution problems in the 2008
Blacksmith Institute Pure Earth, formerly known as the Blacksmith Institute, is a New York City-based international not-for-profit organization founded in 1999 that works to identify, clean up, and solve pollution problems in low- and middle-income countries, where hig ...
World's Worst Polluted Places report. Outdoor air pollution alone causes 2.1 to 4.21 million deaths annually. Overall, air pollution causes the deaths of around 7 million people worldwide each year, and is the world's largest single environmental health risk. Productivity losses and degraded quality of life caused by air pollution are estimated to cost the
world economy The world economy or the global economy is the economy of all humans of the world, referring to the global economic system which includes all economic activities which are conducted both within and between nations, including production (economics ...
$5 trillion per year. Various pollution control technologies and strategies are available to reduce air pollution. To reduce the impacts of air pollution, both international and national legislation and regulation have been implemented to regulate air pollution. Local laws where well enforced in cities have led to strong
public health Public health has been defined as "the science and art of preventing disease", prolonging life and improving quality of life Quality of life (QOL) is defined by the World Health Organization The World Health Organization (WHO) is a lis ...

public health
improvements. At the international level some of these efforts have been successful, for example the
Montreal Protocol The largest Antarctic ozone hole recorded as of September 2006 The Montreal Protocol is an international treaty A treaty is a formal, legally binding written agreement between actors in international law International law, also known ...
which successful at reducing release of harmful ozone depleting chemicals or 1985 Helsinki Protocol which reduced sulfur emissions, while other attempts have been less rapid in implementation, such as
international action on climate change International is an adjective (also used as a noun) meaning "between nations". International may also refer to: Music Albums * International (Kevin Michael album), ''International'' (Kevin Michael album), 2011 * International (New Order album), '' ...
.


Pollutants

An air pollutant is a material in the air that can have adverse effects on humans and the ecosystem. The substance can be solid particles, liquid droplets, or gases. 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 Carbon monoxide (chemical formula CO) is a colorless, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom. It is the simplest molecule of the oxocarbon family. In ...

carbon monoxide
gas from motor vehicle exhausts or
sulfur dioxide Sulfur dioxide (-recommended spelling) or sulphur dioxide (traditional ) is the with the formula . It is a responsible for the smell of burnt es. It is released naturally by and is produced as a by-product of extraction and the burning of ...
released from factories. Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact.
Ground level ozones over the period 1979 to 2000. In June to August, photochemical ozone production causes very high concentrations over the East Coast of the US and China. Ozone Ozone (), or trioxygen, is an inorganic molecule File:Pentacene on Ni(111) STM.jp ...
is a prominent example of a secondary pollutant. Some pollutants may be both primary and secondary: they are both emitted directly and formed from other primary pollutants. Pollutants emitted into the atmosphere by human activity include: *
Carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

Carbon dioxide
() – Because of its role as a
greenhouse gas A greenhouse gas (GHG or GhG) is a gas Gas is one of the four fundamental states of matter (the others being solid, liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformat ...
it has been described as "the leading pollutant" and "the worst climate pollutant". Carbon dioxide is a natural component of the atmosphere, essential for plant life and given off by the human
respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network Network and networking may refer to: Arts, entertainment, and media * ''Network'' (1976 film), a 1976 Ame ...

respiratory system
. This question of terminology has practical effects, for example as determining whether the U.S. Clean Air Act is deemed to regulate emissions. currently forms about 410 parts per million (ppm) of earth's atmosphere, compared to about 280 ppm in pre-industrial times, and billions of metric tons of are emitted annually by burning of
fossil fuels A fossil fuel is a hydrocarbon In organic chemistry, a hydrocarbon is an organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen che ...
. increase in earth's atmosphere has been accelerating. *
Sulfur oxide Sulfur oxide refers to many types of sulfur and oxygen containing compounds such as SO, SO2, SO3, S7O2, S6O2, S2O2, etc. Sulfur oxide (SO''x'') refers to one or more of the following: * Lower sulfur oxides (S''n''O, S7O2 and S6O2) * Sulfur monox ...
s (SOx) – 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 Acid rain is a rain or any other form of Precipitation (meteorology), precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals, and infras ...
is formed. This is one of the causes for concern over the environmental impact of the use of these fuels as power sources. *
Nitrogen oxide Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds: Charge-neutral * Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide * Nitrogen dioxide (NO2), nitrogen(IV) oxide * Nitrogen trioxide (NO ...
s (NOx) – Nitrogen oxides, particularly
nitrogen dioxide Nitrogen dioxide is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by hav ...

nitrogen dioxide
, are expelled from high temperature combustion, and are also produced during
thunderstorms A thunderstorm, (also known as an electrical storm or a lightning storm) is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. (There are relativitly weak thunderstorms, ...

thunderstorms
by
electric discharge An electric discharge is the release and transmission of electricity in an applied electric field through a medium such as a gas.American Geophysical Union, National Research Council (U.S.). Geophysics Study Committee (1986) The earth's electrical ...
. They can be seen as a brown
haze Haze is traditionally an in which dust, smoke, and other dry obscure the clarity of the sky. The manual of codes includes a classification of horizontal obscuration into categories of fog, , , , haze, smoke, , dust, sand, and snow. Sou ...

haze
dome above or a 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. *
Carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom. It is the simplest molecule of the oxocarbon family. In ...

Carbon monoxide
(CO) – CO is a colorless, odorless, toxic gas. It is a product of
combustion Combustion, or burning, is a high-temperature exothermic In thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, radiation, and physical pro ...
of fuel such as natural gas, coal or wood. Vehicular exhaust contributes to the majority of carbon monoxide let into our 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. *
Volatile organic compounds Volatile organic compounds (VOC) are organic chemicals , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's abilit ...

Volatile organic compounds
(VOC) – VOCs are a well-known outdoor air pollutant. They are categorized as either methane (CH4) or non-methane (NMVOCs). Methane is an extremely efficient greenhouse gas which contributes to enhanced
global warming Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been , but the current changes are more rapid than any known events in Earth's history. The main cau ...

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. *
Particulate matter upright=1.7, Movie map of distribution of aerosol particles, based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite: * Green areas show aerosol plumes dominated by larger particles. * Red area ...
/ particles, alternatively referred to as particulate matter (PM), atmospheric particulate matter, or fine particles, are tiny particles of solid or liquid suspended in a gas. In contrast,
aerosol An aerosol (abbreviation of "aero-solution") is a suspension Suspension or suspended may refer to: Science and engineering * Suspension (topology), in mathematics * Suspension (dynamical systems), in mathematics * Suspension of a ring, in mathe ...

aerosol
refers to combined particles and gas. Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes also generate significant amounts of aerosols. Averaged worldwide, anthropogenic aerosols—those made by human activities—currently account for approximately 10 percent of our atmosphere. Increased levels of fine particles in the air are linked to health hazards such as heart disease, altered lung function and lung cancer. Particulates are related to respiratory infections and can be particularly harmful to those already suffering from conditions like
asthma Asthma is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank Consolidation", M. E. Sharpe, Inc., 2002 based in Greenwich, ...

asthma
. * Persistent free radicals connected to airborne fine particles are linked to cardiopulmonary disease. * Toxic
metal A metal (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is appro ...

metal
s, such as
lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate h ...

lead
and
mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

mercury
, especially their compounds. *
Chlorofluorocarbons Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain only (C), (H), (Cl), and (F), produced as derivatives of , , and . They are also commonly known by the brand name . ...
(CFCs) – harmful to the ; emitted from products are currently banned from use. These are gases which are released from air conditioners, refrigerators, aerosol sprays, etc. On release into the air, CFCs rise to the
stratosphere File:Stratosphere Temperature Trend.jpg, This image shows the temperature trend in the lower stratosphere as measured by a series of satellite-based instruments between January 1979 and December 2005. The lower stratosphere is centered around 18 k ...

stratosphere
. Here they come in contact with other gases and damage the . This allows harmful ultraviolet rays to reach the earth's surface. This can lead to skin cancer, eye disease and can even cause damage to plants. *
Ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...
– emitted mainly by agricultural waste.
Ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...

Ammonia
is a compound with the formula NH3. It is normally encountered as a gas with a characteristic pungent odor. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to foodstuffs and fertilizers. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceuticals. Although in wide use, ammonia is both caustic and hazardous. In the atmosphere, ammonia reacts with oxides of nitrogen and sulfur to form secondary particles. *
Odor An odor () or odour (; ) is caused by one or more volatilized s that are generally found in low concentrations that humans and animals can perceive by their of . An odor is also called a "smell" or a "scent", which can refer to either a plea ...
s — such as from garbage, sewage, and industrial processes * Radioactive pollutants – produced by nuclear explosions, nuclear events, war
explosives An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion An explosion is a rapid expansion in volume associated with an extremely vigorous outward release o ...
, and natural processes such as the
radioactive decay Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

radioactive decay
of
radon Radon is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same numbe ...

radon
. Secondary pollutants include: * Particulates created from gaseous primary pollutants and compounds in photochemical smog.
Smog Smog, or smoke fog, is a type of intense air pollution Air pollution is the presence of substances in the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', mea ...

Smog
is a kind of air pollution. Classic smog results from large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide. Modern smog does not usually come from coal but from vehicular and industrial emissions that are acted on in the atmosphere by
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that stud ...

ultraviolet
light from the sun to form secondary pollutants that also combine with the primary emissions to form photochemical smog. *
Ground level ozones over the period 1979 to 2000. In June to August, photochemical ozone production causes very high concentrations over the East Coast of the US and China. Ozone Ozone (), or trioxygen, is an inorganic molecule File:Pentacene on Ni(111) STM.jp ...
(O3) formed from NOx and VOCs. Ozone (O3) is a key constituent of the troposphere. It is also an important constituent of certain regions of the stratosphere commonly known as the Ozone layer. Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the atmosphere by day and by night. At abnormally high concentrations brought about by human activities (largely the combustion of fossil fuel), it is a pollutant and a constituent of smog. *
Peroxyacetyl nitrate Peroxyacetyl nitrate is a peroxyacyl nitrate. It is a secondary pollutant present in photochemical smog. It is thermally unstable and decomposes into peroxyethanoyl radicals and nitrogen dioxide gas. It is a Tears, lachrymatory substance, meaning ...

Peroxyacetyl nitrate
(C2H3NO5) – similarly formed from NOx and VOCs. Minor air pollutants include: * A large number of minor
hazardous air pollutants Air pollution is the presence of substances in the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gas ...
. Some of these are regulated in USA under the Clean Air Act and in Europe under the Air Framework Directive * A variety of
persistent organic pollutant Persistent organic pollutants (POPs), sometimes known as "forever chemicals", are organic compounds , CH4; is among the simplest organic compounds. In chemistry Chemistry is the science, scientific study of the properties and behavior of ...
s, which can attach to particulates
Persistent organic pollutants Persistent organic pollutants (POPs), sometimes known as "forever chemicals", are organic compounds , CH4; is among the simplest organic compounds. In chemistry Chemistry is the science, scientific study of the properties and behavior of ...
(POPs) are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of this, they have been observed to persist in the environment, to be capable of long-range transport,
bioaccumulateBioaccumulation is the gradual accumulation of substances, such as pesticides Pesticides are substances that are meant to control pests Pest or The Pest may refer to: Science and medicine * Pest (organism), an animal or plant detrimental to hum ...
in human and animal tissue, in food chains, and to have potentially significant impacts on human health and the environment.


Sources


Anthropogenic (human-made) sources

These are mostly related to the burning of fuel. * Stationary sources include smoke stacks of
fossil fuel power station A fossil fuel power station is a thermal power station A thermal power station is a power station in which heat energy is converted to electricity. Typically, fuel is used to boil water in a large pressure vessel to produce high-pressure ...
s (see for example
environmental impact of the coal industry The health and environmental impact of the coal industry includes issues such as land use Land use involves the management and modification of natural environment or wilderness Wilderness or wildlands (usually in the plural), are natural e ...
), manufacturing facilities (factories) and waste incinerators, as well as furnaces and other types of fuel-burning heating devices. In developing and poor countries, traditional biomass burning is the major source of air pollutants; traditional biomass includes wood, crop waste and dung. * Mobile sources include
motor vehicles File:Yangzhou-WenchangLu-electric-bicycles-3278.jpg, Electric bicycles parked in Yangzhou's main street, Wenchang Lu. They are a very common way of transport in this city, in some areas almost outnumbering regular bicycles A motor vehicle, also kno ...
, trains (particularly
diesel locomotive -operated locos show three styles of diesel locomotive body: box cab (rear), hood unit running long hood forward. Image:BNSF GP60B 346.jpg, 200px, BNSF Railway, BNSF EMD GP60B, GP60B #346, a cabless hood unit A hood unit, in North American rai ...
s and DMUs), marine vessels and aircraft. *
Controlled burn A controlled or prescribed burn, also known as hazard reduction burning, backfire, swailing, or a burn-off, is a fire set intentionally for purposes of forest managementForest management is a branch of forestry concerned with overall ad ...
practices in agriculture and forest management. Controlled or prescribed burning is a technique sometimes used in forest management, farming, prairie restoration or greenhouse gas abatement. Fire is a natural part of both forest and grassland ecology and controlled fire can be a tool for foresters. Controlled burning stimulates the germination of some desirable forest trees, thus renewing the forest. There are also sources from processes other than combustion * Fumes from
paint Paint is any pigmented liquid A liquid is a nearly incompressible In fluid mechanics Fluid mechanics is the branch of physics concerned with the mechanics Mechanics (Ancient Greek, Greek: ) is the area of physics concerned wi ...

paint
,
hair spray Hair spray (also hair lacquer or spritz) is a common cosmetic Cosmetic may refer to: *Cosmetics, or make-up, substances to enhance the beauty of the human body, apart from simple cleaning *Cosmetic, an adjective describing beauty, aesthetics, or a ...
,
varnish Varnish is a clear transparent Transparency, transparence or transparent most often refer to transparency and translucency, the physical property of allowing the transmission of light through a material. They may also refer to: Literal uses ...

varnish
,
aerosol sprayAerosol spray is a type of dispensing system which creates an aerosol mist of liquid particles. It comprises a can or bottle that contains a payload, and a propellant under pressure. When the container's valve is opened, the payload is forced out of ...
s and other solvents. These can be substantial; emissions from these sources was estimated to account for almost half of pollution from
volatile organic compounds Volatile organic compounds (VOC) are organic chemicals , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's abilit ...

volatile organic compounds
in the Los Angeles basin in the 2010s. * Waste deposition in
landfill A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste Waste (or wastes) are unwanted or unusable materials. Waste is any substance which is discarded after primar ...

landfill
s, which generate
methane Methane (, ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth ...
. Methane is highly flammable and may form explosive mixtures with air. Methane is also an asphyxiant and may displace oxygen in an enclosed space. Asphyxia or suffocation may result if the oxygen concentration is reduced to below 19.5% by displacement. * Military resources, such as
nuclear weapon A nuclear weapon (also known as an atom bomb, atomic bomb, nuclear bomb or nuclear warhead, and colloquially as an A-bomb or nuke) is an explosive device that derives its destructive force from nuclear reaction In nuclear physics and nucl ...
s,
toxic gas Many gases have toxicity, toxic properties, which are often assessed using the LC50 (median lethal dose) measure. In the United States, many of these gases have been assigned an NFPA 704 health rating of 4 (may be fatal) or 3 (may cause serious o ...
es,
germ warfare A culture of '' anthrax.html"_;"title="Bacillus_anthracis'',_the_causative_agent_of_anthrax">Bacillus_anthracis'',_the_causative_agent_of_anthrax,_which_was_repeatedly_employed_for_biological_warfare. Biological_warfare,_also_known_as_germ_wa ...
and
rocket A rocket (from it, rocchetto, , bobbin/spool) is a spacecraft A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite alt=, A full-size model of the Earth observation satellite ERS 2 ...

rocket
ry. * Fertilized farmland may be a major source of nitrogen oxides.


Natural sources

*
Dust Dust is made of s of solid . On Earth, it generally consists of particles in the that come from various sources such as lifted by wind (an ), , and . Dust in homes is composed of about 20–50% dead . The rest, and in offices, and other ...
from natural sources, usually large areas of land with little vegetation or no vegetation *
Methane Methane (, ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth ...
, emitted by the
digestion Digestion is the breakdown of large insoluble food Food is any substance consumed to provide nutritional Nutrition is the biochemical Biochemistry or biological chemistry, is the study of chemical processes within and relating to liv ...
of food by
animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells ...

animal
s, for example
cattle Cattle, taurine cattle, Eurasian cattle, or European cattle (''Bos taurus'' or ''Bos primigenius taurus'') are large domestication, domesticated Cloven hoof, cloven-hooved herbivores. They are a prominent modern member of the subfamily Bovinae ...

cattle
*
Radon Radon is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that c ...

Radon
gas from
radioactive decay Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

radioactive decay
within the
Earth's crust 350px, Plates in the crust of Earth Earth's crust is a thin shell on the outside of Earth, accounting for less than 1% of Earth's volume. It is the top component of the lithosphere, a division of Earth's layers that includes the Crust (geology), ...
. Radon is a colorless, odorless, naturally occurring, radioactive
noble gas The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under Standard conditions for temperature and pressure, standard conditions, they are all odorl ...
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 A cigarette is a narrow cylinder containing burnable material, typically tobacco Tobacco is the common name of several plants in the ' of the , and the general term for any product prepared from the of these plants. of tobacco are ...

cigarette
smoking. *
Smoke Smoke is a collection of airborne and es emitted when a material undergoes or , together with the quantity of air that is or otherwise mixed into the mass. It is commonly an unwanted of fires (including s, s, s, s, and s), but may als ...

Smoke
and
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom. It is the simplest molecule of the oxocarbon family. In ...

carbon monoxide
from
wildfires A wildfire, bushfire, wildland fire or rural fire is an unplanned, unwanted, uncontrolled fire BBQ. Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction ...
. During periods of active wildfires, smoke from uncontrolled biomass combustion can make up almost 75% of all air pollution by concentration. * Vegetation, in some regions, emits environmentally significant amounts of
volatile organic compounds Volatile organic compounds (VOC) are organic chemicals , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's abilit ...

volatile organic compounds
(VOCs) on warmer days. These VOCs react with primary anthropogenic pollutants—specifically, NOx, SO2, and anthropogenic organic carbon compounds — to produce a seasonal haze of secondary pollutants. 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. *
Volcanic A volcano is a rupture in the crust of a planetary-mass object A planet is an astronomical body orbit In physics, an orbit is the gravitationally curved trajectory of an physical body, object, such as the trajectory of a planet ar ...

Volcanic
activity, which produces
sulfur Sulfur (in nontechnical British English: sulphur) is a chemical element In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: th ...

sulfur
,
chlorine Chlorine is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemica ...

chlorine
, and ash particulates


Emission factors

Air pollutant emission factors are reported representative values that attempt to relate the quantity of a pollutant released to the ambient air with an activity associated with the release of that pollutant. These factors are usually expressed as the weight of pollutant divided by a unit weight, volume, distance, or duration of the activity emitting the pollutant (e.g., kilograms of particulate emitted per
tonne The tonne ( or ; symbol: t) is a metric unit of mass equal to 1,000 kilogram The kilogram (also kilogramme) is the base unit of mass Mass is the physical quantity, quantity of ''matter'' in a physical body. It is also a meas ...
of coal burned). Such factors facilitate estimation of emissions from various sources of air pollution. In most cases, these factors are simply averages of all available data of acceptable quality, and are generally assumed to be representative of long-term averages. There are 12 compounds in the list of
persistent organic pollutant Persistent organic pollutants (POPs), sometimes known as "forever chemicals", are organic compounds , CH4; is among the simplest organic compounds. In chemistry Chemistry is the science, scientific study of the properties and behavior of ...
s.
Dioxins Dioxin may refer to: *1,2-Dioxin or 1,4-Dioxin, two unsaturated Heterocyclic#6-Membered rings, heterocyclic 6-membered rings where two carbon atoms have been replaced by oxygen atoms, giving the chemical formula#Molecular formula, molecular formul ...

Dioxins
and
furans Furan is a Heterocyclic compound, heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon Atom, atoms and one oxygen atom. Chemical compounds containing such rings are also referred to as furans. Furan is a co ...

furans
are two of them and intentionally created by combustion of organics, like open burning of plastics. These compounds are also endocrine disruptors and can mutate the human genes. The
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
has published a compilation of air pollutant emission factors for a wide range of industrial sources. The
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use Britain as a synonym for the United Kingdom. Some prefer to use Britain as shorth ...

United Kingdom
,
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
,
Canada Canada is a country in the northern part of North America North America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, ...

Canada
and many other countries have published similar compilations, as well as the
European Environment Agency The European Environment Agency (EEA) is the agency of the European Union (EU) which provides independent information on the environment. Definition The European Environment Agency (EEA) is the agency of the European Union (EU) which provides in ...
.


Exposure

Air pollution risk is a function of the hazard of the pollutant and the exposure to that pollutant. Air pollution exposure can be expressed for an individual, for certain groups (e.g. neighborhoods or children living in a country), or for entire populations. For example, one may want to calculate the exposure to a hazardous air pollutant for a geographic area, which includes the various microenvironments and age groups. This can be calculated 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 age and other demographic groups, especially infants, children, pregnant women and other sensitive subpopulations. The exposure to an air pollutant must integrate the concentrations of the air pollutant with respect to the time spent in each setting and the respective inhalation rates for each subgroup for each specific time that the subgroup is in the setting and engaged in particular activities (playing, cooking, reading, working, spending time in traffic, etc.). For example, a small child's inhalation rate will be less than that of an adult. A child engaged in vigorous exercise will have a higher respiration rate than the same child in a sedentary activity. The daily exposure, then, needs to reflect the time spent in each micro-environmental setting and the type of activities in these settings. The air pollutant concentration in each microactivity/microenvironmental setting is summed to indicate the exposure. For some pollutants such as
black carbon Chemically, black carbon (BC) is a component of fine Particulates, particulate matter (PM ≤ 2.5 µm in aerodynamic diameter). Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion o ...
, traffic related exposures may dominate total exposure despite short exposure times since high concentrations coincide with proximity to major roads or participation to (motorized) traffic. 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.


Indoor air quality

A lack of ventilation indoors concentrates air pollution where people often spend the majority of their time.
Radon Radon is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that c ...

Radon
(Rn) gas, a
carcinogen A carcinogen is any substance, radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide A nuclide (or nucleide, from atomic nucleus, nucleus, also known as nuclear species) is a class of atoms characte ...
, is exuded from the Earth in certain locations and trapped inside houses. Building materials including
carpet A carpet is a textile A textile is a flexible material made by creating an interlocking bundle of yarn Yarn is a long continuous length of interlocked fibres, suitable for use in the production of textiles, sewing, crocheting, knit ...

carpet
ing and
plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer In woodworking, veneer refers to thin slices of wood and sometimes bark, usually thinner than 3 mm (1/8 inch), that typically are glued onto core panels (typic ...

plywood
emit
formaldehyde Formaldehyde ( , also ) (systematic nameA systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance A chemical substance is a form of matter In classical physics and general chemist ...
(H2CO) gas. Paint and solvents give off
volatile organic compounds Volatile organic compounds (VOC) are organic chemicals , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen chemical bond, bonds. Due to carbon's abilit ...

volatile organic compounds
(VOCs) as they dry.
Lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate h ...

Lead
paint can degenerate into
dust Dust is made of s of solid . On Earth, it generally consists of particles in the that come from various sources such as lifted by wind (an ), , and . Dust in homes is composed of about 20–50% dead . The rest, and in offices, and other ...
and be inhaled. Intentional air pollution is introduced with the use of
air freshener File:Automatic Air Freshner.jpg, 300px, An automatic air freshener Air fresheners are consumer products that typically emit fragrance and are used in homes or commercial interiors such as restrooms, foyers, hallways, vestibules and other smaller in ...
s,
incense Incense is aromatic biotic material that releases fragrant smoke when burnt. The term is used for either the material or the aroma. Incense is used for aesthetic reasons, religious worship, aromatherapy, meditation, and ceremony. It may also be u ...

incense
, and other scented items. Controlled wood fires in cook stoves and
fireplace A fireplace or hearth A hearth is the place in a where a is or was traditionally kept for home heating and for , usually constituted by at least a horizontal hearthstone and often enclosed to varying degrees by any combination of , , , ...

fireplace
s can add significant amounts of harmful smoke particulates into the air, inside and out. Indoor pollution fatalities may be caused by using
pesticide Pesticides are substances that are meant to control pests Pest or The Pest may refer to: Science and medicine * Pest (organism), an animal or plant detrimental to humans or human concerns ** Weed, a plant considered undesirable * Infectious d ...
s and other chemical sprays indoors without proper ventilation. Carbon monoxide poisoning and fatalities are often caused by faulty vents and chimneys, or by the burning of
charcoal Charcoal is a lightweight black carbon Carbon (from la, carbo "coal") is a with the C and 6. It is lic and —making four s available to form s. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025 perc ...

charcoal
indoors or in a confined space, such as a tent. Chronic
carbon monoxide poisoning Carbon monoxide poisoning typically occurs from breathing Breathing (or ventilation) is the process of moving air out and in the lungs to facilitate gas exchange with the internal environment, mostly to flush out carbon dioxide and bring ...
can result even from poorly-adjusted
pilot light An aircraft pilot or aviator is a person who controls the flight of an aircraft An aircraft is a vehicle or machine that is able to fly Flies are insect Insects or Insecta (from Latin Latin (, or , ) is a classical lan ...
s. Traps are built into all domestic
plumbing Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delive ...

plumbing
to keep sewer gas and
hydrogen sulfide Hydrogen sulfide is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by havi ...

hydrogen sulfide
, out of interiors. Clothing emits
tetrachloroethylene Tetrachloroethylene, also known under the systematic name tetrachloroethene, or perchloroethylene, and many other names (and abbreviations such as "perc" or "PERC", and "PCE"), is a chlorocarbon An organochloride, organochlorine compound, chloro ...

tetrachloroethylene
, or other dry cleaning fluids, for days after
dry cleaning Dry cleaning is any cleaning process for clothing A kanga, worn throughout the African Great Lakes region Clothing (also known as clothes, apparel, and attire) are items worn on the body. Typically, clothing is made of fabrics or textiles ...
. Though its use has now been banned in many countries, the extensive use of
asbestos Asbestos (pronounced: or ) is a naturally occurring fibrous silicate mineral Silicate minerals are rock-forming mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fair ...
in industrial and domestic environments in the past has left a potentially very dangerous material in many localities.
Asbestosis Asbestosis is long-term inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogen In biology Biology is the natural science that studies life and ...

Asbestosis
is a chronic
inflammatory Inflammatory may refer to: * Inflammation, a biological response to harmful stimuli * The word ''inflammatory'' is also used to refer literally to fire and flammability, and figuratively in relation to comments that are Agent provocateur, provocati ...
medical condition affecting the tissue of the
lung The lungs are the primary organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parenchyma ...

lung
s. It occurs after long-term, heavy exposure to asbestos from asbestos-containing materials in structures. Sufferers have severe
dyspnea Shortness of breath (SOB), also known as dyspnea (BrE British English (BrE) is the standard dialect A standard language (also standard variety, standard dialect, and standard) is a language variety that has undergone substantial codificat ...
(shortness of breath) and are at an increased risk regarding several different types of
lung cancer Lung cancer, also known as lung carcinoma, since about 98–99% of all lung cancers are carcinomas, is a malignant lung tumor ''Lung tumors'' are neoplastic lung nodules. These include: Primary tumorA primary tumor is a tumor A neoplas ...

lung cancer
. As clear explanations are not always stressed in non-technical literature, care should be taken to distinguish between several forms of relevant diseases. According to th
World Health Organization (WHO)
these may be defined as
asbestosis Asbestosis is long-term inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogen In biology Biology is the natural science that studies life and ...

asbestosis
, ''lung cancer'', and ''
peritoneal mesothelioma Peritoneal mesothelioma is the name given to the cancer that attacks the lining of the abdomen. This type of cancer affects the lining that protects the contents of the abdomen and which also provides a lubricating fluid to enable the organs to mov ...
'' (generally a very rare form of cancer, when more widespread it is almost always associated with prolonged exposure to asbestos). Biological sources of air pollution are also found indoors, as gases and airborne particulates.
Pet A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock or a laboratory animal. Popular pets are often considered to have attractive appearances, Animal cognitio ...

Pet
s produce dander, people produce dust from minute skin flakes and decomposed hair,
dust mites House dust mites (HDM, or simply dust mites) are various species of Acariformes, acariform mites belonging to the family Pyroglyphidae that are found in association with dust in dwellings. They are known for causing an dust mite allergy, allergy. ...

dust mites
in bedding, carpeting and furniture produce enzymes and micrometre-sized fecal droppings, inhabitants emit methane,
mold A mold () or mould () is a fungus A fungus (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of ...
forms on walls and generates
mycotoxins A mycotoxin (from the Greek μύκης , "fungus" and τοξίνη , "toxin") is a toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism In biology, an organism (from A ...
and spores,
air conditioning Air conditioning (also A/C, air conditioner) is the process of removing heat and controlling the humidity Humidity is the concentration of water vapour (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 ...
systems can incubate
Legionnaires' disease Legionnaires' disease is a form of atypical pneumonia Atypical pneumonia, also known as walking pneumonia, is any type of pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs kno ...
and mold, and
houseplant A houseplant is a plant Plants are mainly multicellular organisms, predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, th ...

houseplant
s, soil and surrounding
gardens A garden is a planned space, usually outdoors, set aside for the display, cultivation, or enjoyment of plant Plants are mainly multicellular organisms, predominantly photosynthetic Photosynthesis is a process used by plants and other ...

gardens
can produce
pollen Pollen is a powdery substance consisting of pollen grains which are Sporophyte, microsporophytes of spermatophyta, seed plants, which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the ga ...

pollen
, dust, and mold. Indoors, the lack of air circulation allows these airborne pollutants to accumulate more than they would otherwise occur in nature.


Health effects

Even at levels lower than those considered safe by United States regulators, exposure to three components of air pollution, fine
particulate Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM), or suspended particulate matter (SPM) – are microscopic The microscopic scale (from , ''mikrós'', "small" and σκοπ ...
matter,
nitrogen dioxide Nitrogen dioxide is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by hav ...

nitrogen dioxide
and
ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lower ...

ozone
, correlates with cardiac and respiratory illness. In 2012, air pollution caused premature deaths on average of 1 year in Europe, and was a significant
risk factor In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted wiktionary:determine, scientific m ...
for a number of pollution-related diseases, including
respiratory infection Respiratory tract infections (RTIs) are infectious diseases involving the respiratory tract. An infection of this type usually is further classified as an upper respiratory tract infection (URI or URTI) or a lower respiratory tract infection (LRI o ...
s,
heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped b ...
,
COPD Chronic obstructive pulmonary disease (COPD) is a type of obstructive lung disease characterized by long-term breathing problems and poor airflow. The main symptoms include shortness of breath and cough with sputum production. COPD is a pro ...
,
stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Di ...

stroke
and
lung cancer Lung cancer, also known as lung carcinoma, since about 98–99% of all lung cancers are carcinomas, is a malignant lung tumor ''Lung tumors'' are neoplastic lung nodules. These include: Primary tumorA primary tumor is a tumor A neoplas ...

lung cancer
. The health effects caused by air pollution may include difficulty in breathing, wheezing, coughing,
asthma Asthma is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank Consolidation", M. E. Sharpe, Inc., 2002 based in Greenwich, ...

asthma
and worsening of existing respiratory and cardiac conditions. These effects can result in increased medication use, increased doctor or
emergency department An emergency department (ED), also known as an accident & emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine, the Acute (medicine), acut ...
visits, more hospital admissions and premature death. 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. The most common sources of air pollution include particulates, ozone, nitrogen dioxide, and sulfur dioxide. Children aged less than five years that live in developing countries are the most vulnerable population in terms of total deaths attributable to indoor and outdoor air pollution.


Mortality

The
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations United Nations Specialized Agencies are autonomous organizations working with the United Nations and each other through the co-ordinating machinery of the Unit ...
estimated in 2014 that every year air pollution causes the premature death of some 7 million people worldwide. Studies published in March 2019 indicated that the number may be around 8.8 million. India has the highest death rate due to air pollution. India also has more deaths from asthma than any other nation according to the World Health Organization. In December 2013 air pollution was estimated to kill 500,000 people in China each year. There is a positive correlation between
pneumonia Pneumonia is an condition of the primarily affecting the small air sacs known as . Symptoms typically include some combination of or dry , , , and . The severity of the condition is variable. Pneumonia is usually caused by with es or , a ...

pneumonia
-related deaths and air pollution from motor vehicle emissions. Annual premature European deaths caused by air pollution are estimated at 430,000-800,000 An important cause of these deaths is nitrogen dioxide and other nitrogen oxides (NOx) emitted by road vehicles. In a 2015 consultation document the UK government disclosed that nitrogen dioxide is responsible for 23,500 premature UK deaths per annum. Across the
European Union The European Union (EU) is a political and economic union of member states that are located primarily in Europe Europe is a which is also recognised as part of , located entirely in the and mostly in the . It comprises the wester ...

European Union
, air pollution is estimated to reduce
life expectancy Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, its current age, and other demographic Demography (from prefix ''demo-'' from Ancient Greek Ancien ...

life expectancy
by almost nine months. Causes of deaths include
stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Di ...

stroke
s,
heart disease Cardiovascular disease (CVD) is a class of diseases that involve the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped b ...
, COPD, lung cancer, and lung infections. Urban outdoor air pollution is estimated to cause 1.3 million deaths worldwide per year. Children are particularly at risk due to the immaturity of their respiratory organ systems. The
US EPA The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
estimated in 2004 that a proposed set of changes in
diesel engine The diesel engine, named after Rudolf Diesel Rudolf Christian Karl Diesel ( (); 18 March 1858 – 29 September 1913) was a German inventor and mechanical engineer, famous for the invention of the Diesel engine The diesel engine, name ...

diesel engine
technology (''Tier 2'') could result in 12,000 fewer ''premature mortalities'', 15,000 fewer
heart attacks A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow Hemodynamics American and British English spelling differences#ae and oe, or haemodynamics are the Fluid dynamics, dynamics of blood flow. The circulatory sy ...

heart attacks
, 6,000 fewer
emergency department An emergency department (ED), also known as an accident & emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine, the Acute (medicine), acut ...
visits by children with asthma, and 8,900 fewer respiratory-related hospital admissions each year in the United States. The US EPA has estimated that limiting ground-level ozone concentration to 65 parts per billion, 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. 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 parts per billion (ppb). A new economic study of the health impacts and associated costs of air pollution in the
Los Angeles Basin The Los Angeles Basin is a sedimentary basin located in southern California Southern California (popularly known as SoCal; es, Sur de California) is a geographic and cultural region that generally comprises the southern portion of the U.S. s ...

Los Angeles Basin
and
San Joaquin Valley , photo = California's Central Valley.JPG , photo_caption = San Joaquin Valley , map_image = California San Joaquin counties.svg , map_caption = A map of the counties encompassing the San Joaquin Valley ecoregion ...
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.
Diesel exhaust Diesel exhaust is the gaseous exhaust produced by a diesel type of internal combustion engine An internal combustion engine (ICE) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber ...
(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. The mechanisms linking air pollution to increased cardiovascular mortality are uncertain, but probably include pulmonary and systemic inflammation. A study by
Greenpeace Greenpeace is an independent global campaigning network. The network comprises 26 independent national/regional organisations in over 55 countries across Europe, the Americas, Africa, Asia and the Pacific, as well as a co-ordinating body, Green ...

Greenpeace
estimates there are 4.5 million annual premature deaths worldwide because of pollutants released by high-emission power stations and vehicle exhausts, 65,000 deaths occur in the Middle East each year due to pollution. A study by scientists of U.K. and U.S. universities that uses a high spatial resolution model and an updated concentration-response function concluded in 2021 that 10.2 million global excess deaths in 2012 and 8.7 million in 2018 – or – were due to air pollution generated by
fossil fuel A fossil fuel is a hydrocarbon In , a hydrocarbon is an consisting entirely of and . Hydrocarbons are examples of s. Hydrocarbons are generally colourless and hydrophobic with only weak odours. Because of their diverse molecular structure ...
combustion, significantly higher than earlier estimates and with spatially subdivided mortality impacts.


Cardiovascular disease

A 2007 review of evidence found that, ambient air pollution exposure is a risk factor correlating with increased total mortality from cardiovascular events (range: 12% to 14% per 10 µg/m3 increase). Air pollution is also emerging as a risk factor for stroke, particularly in developing countries where pollutant levels are highest. A 2007 study found that in women, air pollution is not associated with hemorrhagic but with ischemic stroke. Air pollution was also found to be associated with increased incidence and mortality from coronary stroke in a cohort study in 2011. Associations are believed to be causal and effects may be mediated by vasoconstriction, low-grade inflammation and
atherosclerosis Atherosclerosis is a disease in which the wall of the artery An artery (plural arteries) () is a blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels tr ...

atherosclerosis
Other mechanisms such as autonomic nervous system imbalance have also been suggested.


Lung disease

Research has demonstrated increased risk of developing asthma and COPD from increased exposure to traffic-related air pollution. Additionally, air pollution has been associated with increased hospitalization and mortality from asthma and COPD.
Chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease The lungs are the primary Organ (anatomy), organs of the respiratory system in humans and many other animals including a few fish and some snails. In mammal ...
(COPD) includes diseases such as chronic bronchitis and
emphysema Emphysema, or pulmonary emphysema, is a lower respiratory tract disease, characterised by air-filled spaces ( pneumatoses) in the lung The lungs are the primary organs An organ is a group of tissues with similar functions. Plant lif ...

emphysema
. A study conducted in 1960–1961 in the wake of the
Great Smog The Great Smog of London, or Great Smog of 1952, was a severe air pollution Air pollution is the presence of substances in the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ...
of 1952 compared 293 London residents with 477 residents of Gloucester, Peterborough, and Norwich, three towns with low reported death rates from chronic bronchitis. All subjects were male postal truck drivers aged 40 to 59. Compared to the subjects from the outlying towns, the London subjects exhibited more severe respiratory symptoms (including cough, phlegm, and dyspnea), reduced lung function ( FEV1 and peak flow rate), and increased sputum production and purulence. The differences were more pronounced for subjects aged 50 to 59. The study controlled for age and smoking habits, so concluded that air pollution was the most likely cause of the observed differences. More recent studies have shown that air pollution exposure from traffic reduces lung function development in children and lung function may be compromised by air pollution even at low concentrations. Air pollution exposure also cause lung cancer in non smokers. It is believed that much like
cystic fibrosis Cystic fibrosis (CF) is a genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene In biology, a gene (from ''genos'' "...Wilhelm Johan ...
, by living in a more urban environment serious health hazards become more apparent. Studies have shown that in urban areas patients suffer
mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membrane A mucous membrane or mucosa is a biological membrane, membrane that lines various cavities in the body and covers the surface of internal organs. It consists o ...
hypersecretion, lower levels of lung function, and more self-diagnosis of chronic bronchitis and emphysema.


Cancer (lung cancer)

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
PM2.5 Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM), or suspended particulate matter (SPM) – are microscopic The microscopic scale (from , ''mikrós'', "small" and σκοπ ...
(fine particulates) increases the overall risk of non-accidental mortality by 6% per a 10 microg/m3 increase. Exposure to PM2.5 was also associated with an increased risk of mortality from
lung cancer Lung cancer, also known as lung carcinoma, since about 98–99% of all lung cancers are carcinomas, is a malignant lung tumor ''Lung tumors'' are neoplastic lung nodules. These include: Primary tumorA primary tumor is a tumor A neoplas ...

lung cancer
(range: 15% to 21% per 10 microg/m3 increase) and total cardiovascular mortality (range: 12% to 14% per a 10 microg/m3 increase). 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 PM2.5 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. 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. In 2011, a large Danish epidemiological study found an increased risk of lung cancer for patients who lived in areas with high nitrogen oxide concentrations. In this study, the association was higher for non-smokers than smokers. 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.


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 non-attainment areas—regions in which the concentration of certain air pollutants exceeded federal standards. These dangerous pollutants are known as the criteria pollutants, and include ozone,
particulate matter upright=1.7, Movie map of distribution of aerosol particles, based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite: * Green areas show aerosol plumes dominated by larger particles. * Red area ...
, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. Protective measures to ensure children's health are being taken in cities such as
New Delhi New Delhi (, ''Naī Dillī'') is the capital Capital most commonly refers to: * Capital letter Letter case (or just case) is the distinction between the letters that are in larger uppercase or capitals (or more formally ''majusc ...

New Delhi
, India where buses now use
compressed natural gas Compressed natural gas is a made of petrol which is mainly composed of (CH4), to less than 1% of the volume it occupies at . It is stored and distributed in hard containers at a pressure of , usually in or shapes. CNG is used in traditional ...
to help eliminate the "pea-soup" smog. A recent study in Europe has found that exposure to ultrafine particles can increase
blood pressure Blood pressure (BP) is the pressure Pressure (symbol: ''p'' or ''P'') is the force In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motio ...

blood pressure
in children. According to a WHO report-2018, polluted air leads to the poisoning of millions of children under the age of 15, resulting in the death of some six hundred thousand children annually. Prenatal exposure to polluted air has been linked to a variety of
neurodevelopmental disorders Neurodevelopmental disorders are a group of disorders that affect the development of the nervous system, leading to abnormal brain function which may affect emotion Emotions are biological states associated with all of the nerve systems brou ...
in children. For example, exposure to polycyclic aromatic hydrocarbons (PAH) was associated with reduced IQ scores and symptoms of
anxiety Anxiety is an emotion Emotions are mental state, psychological states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavioural responses, and a degree of pleasure or suffering, disp ...
and
depression Depression may refer to: Mental health * Depression (mood), a state of low mood and aversion to activity * Mood disorders characterized by depression are commonly referred to as simply ''depression'', including: ** Dysthymia ** Major depressive ...
. A 2014 study found that PAHs might play a role in the development of childhood
Attention Deficit Hyperactivity Disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder Neurodevelopmental disorders are a group of disorders that affect the development of the nervous system, leading to abnormal brain function which may affect ...
(ADHD). Researchers have also begun to find evidence for air pollution as a risk factor for
autism spectrum disorder The autism spectrum encompasses a range of neurodevelopmental disorder, neurodevelopmental conditions, including autism and Asperger syndrome, generally known as autism spectrum disorders (ASD). Individuals on the autism spectrum typically exper ...
(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 3-5 years of age. 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.


Infants

Ambient levels of air pollution have been associated with
preterm birth Preterm birth, also known as premature birth, is the Childbirth, birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Very early preterm birth is before 32 weeks, early preterm birth ...
and
low birth weight Low birth weight (LBW) is defined by the World Health Organization as a birth weight of an infant of or less, regardless of gestational age. Infants born with LBW have added health risks which require close management, often in a neonatal intensive ...
. 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 PM2.5. Women in regions with greater than average PM2.5 levels had statistically significant higher odds of pregnancy resulting in a low-birth weight infant even when adjusted for country-related variables. The effect is thought to be from stimulating
inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogen In biology Biology is the natural science that studies life and living organisms, including their anato ...
and increasing
oxidative stress (mild reducing agent) are added to powdered potassium permanganate Potassium permanganate is an inorganic compound with the chemical formula KMnO4 and composed of potassium ion, K+ and permanganate, . It is a purplish-black crystalline salt, th ...
. A study by the University of York found that in 2010 exposure to PM2.5 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. 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 Biomass is plant or animal material used as fuel to produce electricity Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position ...
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 A dust storm, also called sandstorm, is a meteorological phenomenon common in arid A region is arid when it is characterized by a severe lack of available water, to the extent of hindering or preventing the growth and development of pl ...

dust storms
. The United States had an estimated 50,000 preterm births associated with exposure to PM2.5 in 2010. A study performed by Wang, et al. between the years of 1988 and 1991 has found a correlation between
sulfur dioxide Sulfur dioxide (-recommended spelling) or sulphur dioxide (traditional ) is the with the formula . It is a responsible for the smell of burnt es. It is released naturally by and is produced as a by-product of extraction and the burning of ...
(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. 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 PM2.5 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.


"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 PM2.5 meet federal standards, Medicare recipients who are exposed to more air pollution have higher mortality rates. A 2005 scientific study for the British Columbia Lung Association showed that a small improvement in air quality (1% reduction of ambient PM2.5 and ozone concentrations) would produce $29 million in annual savings in the
Metro Vancouver The Metro Vancouver Regional District (MVRD), or simply Metro Vancouver, is a Canadian political subdivision and corporate entity representing the metropolitan area of Greater Vancouver, designated by provincial legislation as one of the 28 re ...
region in 2010. This finding is based on health valuation of lethal (death) and sub-lethal (illness) affects. In 2020, scientists found that the boundary layer air over the Southern Ocean around Antarctica is unpolluted by humans.


Central nervous system

Data is accumulating that air pollution exposure also affects the
central nervous system The central nervous system (CNS) is the part of the nervous system In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecu ...

central nervous system
. In a June 2014 study conducted by researchers at the
University of Rochester The University of Rochester (U of R, UR, or U of Rochester) is a in . The university grants and s, including and s. The University of Rochester enrolls approximately 6,800 undergraduates and 5,000 graduate students. Its 158 buildings hous ...
Medical Center, published in the journal ''
Environmental Health Perspectives ''Environmental Health Perspectives'' (''EHP'') is a peer-reviewed Peer review is the evaluation of work by one or more people with similar competencies as the producers of the work ( peers). It functions as a form of self-regulation by qual ...
'', it was discovered that early exposure to air pollution causes the same damaging changes in the brain as
autism Autism is a developmental disorder Developmental disorders comprise a group of psychiatric conditions originating in childhood that involve serious impairment in different areas. There are several ways of using this term. The most narro ...

autism
and
schizophrenia Schizophrenia is a mental disorder A mental disorder, also called a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may b ...

schizophrenia
. The study also shows that air pollution also affected
short-term memory Short-term memory (or "primary" or "active memory") is the capacity for holding, but not manipulating, a small amount of information in mind The mind is the set of faculties responsible for mental Phenomenon, phenomena. Often the term is also ...
, learning ability, and
impulsivity In psychology Psychology is the science of mind and behavior. Psychology includes the study of consciousness, conscious and Unconscious mind, unconscious phenomena, as well as feeling and thought. It is an academic discipline of immense sco ...
. Lead researcher Professor Deborah Cory-Slechta said that "When we looked closely at the ventricles, we could see that the
white matter White matter refers to areas of the central nervous system The central nervous system (CNS) is the part of the nervous system In biology Biology is the natural science that studies life and living organisms, including their anato ...
that normally surrounds them hadn't fully developed. It appears that
inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogen In biology Biology is the natural science that studies life and living organisms, including their anato ...
had damaged those
brain cells Brain cells make up the functional tissue of the brain. The rest of the brain tissue is structural or connective called the stroma which includes blood vessel The blood vessels are the components of the circulatory system that transport blood ...
and prevented that region of the brain from developing, and the ventricles simply expanded to fill the space. Our findings add to the growing body of evidence that air pollution may play a role in
autism Autism is a developmental disorder Developmental disorders comprise a group of psychiatric conditions originating in childhood that involve serious impairment in different areas. There are several ways of using this term. The most narro ...

autism
, as well as in other
neurodevelopmental disorders Neurodevelopmental disorders are a group of disorders that affect the development of the nervous system, leading to abnormal brain function which may affect emotion Emotions are biological states associated with all of the nerve systems brou ...
." In a study of mice, air pollution also has a more significant negative effect on males than on females. 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
Harvard University Harvard University is a private Private or privates may refer to: Music * "In Private "In Private" was the third single in a row to be a charting success for United Kingdom, British singer Dusty Springfield, after an absence of nearly t ...

Harvard University
and SUNY Upstate Medical University and Syracuse University measured the cognitive performance of 24 participants in three different controlled laboratory atmospheres that simulated those found in "conventional" and "green" buildings, as well as green buildings with enhanced ventilation. Performance was evaluated objectively using the widely used Strategic Management Simulation software simulation tool, which is a well-validated assessment test for executive decision-making in an unconstrained situation allowing initiative and improvisation. Significant deficits were observed in the performance scores achieved in increasing concentrations of either
volatile organic compound Volatile organic compounds (VOC) are organic compound, organic chemicals that have a high vapour pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the sur ...
s (VOCs) or
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
, while keeping other factors constant. The highest impurity levels reached are not uncommon in some classroom or office environments. Air pollution increases the risk of dementia in people over 50 years old.


Agricultural effects

In India in 2014, it was reported that air pollution by
black carbon Chemically, black carbon (BC) is a component of fine Particulates, particulate matter (PM ≤ 2.5 µm in aerodynamic diameter). Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion o ...
and ground level ozone had reduced crop yields in the most affected areas by almost half in 2011 when compared to 1980 levels.


Economic effects

Air pollution costs the
world economy The world economy or the global economy is the economy of all humans of the world, referring to the global economic system which includes all economic activities which are conducted both within and between nations, including production (economics ...
$5 trillion per year as a result of productivity losses and degraded quality of life, according to a joint study by the
World Bank The World Bank is an international financial institution An international financial institution (IFI) is a financial institution that has been established (or chartered) by more than one country, and hence is subject to international law. Its o ...
and the
Institute for Health Metrics and Evaluation The Institute for Health Metrics and Evaluation (IHME) is a research institute working in the area of global health statistics and impact evaluation at the University of Washington in Seattle. The Institute is headed by Christopher J.L. Murray, ...
(IHME) at the
University of Washington The University of Washington (UW, simply Washington, or informally U-Dub) is a public In public relations Public relations (PR) is the practice of managing and disseminating information from an individual or an organization ...

University of Washington
. These productivity losses are caused by deaths due to diseases caused by air pollution. One out of ten deaths in 2013 was caused by diseases associated with air pollution and the problem is getting worse. The problem is even more acute in the
developing world A developing country is a sovereign state A sovereign state is a political entity A polity is an identifiable political entity—any group of people who have a collective identity, who are organized by some form of Institutionalisation, ...
. "Children under age 5 in lower-income countries are more than 60 times as likely to die from exposure to air pollution as children in high-income countries." The report states that additional economic losses caused by air pollution, including health costs and the adverse effect on agricultural and other productivity were not calculated in the report, and thus the actual costs to the world economy are far higher than $5 trillion.


Other effects

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.


Historical disasters

The world's worst short-term civilian pollution crisis was the 1984
Bhopal Disaster The Bhopal disaster, also referred to as the Bhopal gas tragedy, was a gas leak incident on the night of 2–3 December 1984 at the Union Carbide India Limited (UCIL) pesticide Pesticides are substances that are meant to control pests. ...
in
India India, officially the Republic of India (Hindi Hindi (Devanagari: , हिंदी, ISO 15919, ISO: ), or more precisely Modern Standard Hindi (Devanagari: , ISO 15919, ISO: ), is an Indo-Aryan language spoken chiefly in Hindi Belt, ...

India
. Leaked industrial vapours from the Union Carbide factory, belonging to Union Carbide, Inc., U.S.A. (later bought by
Dow Chemical Company The Dow Chemical Company (TDCC) is an American multinational chemical corporation headquartered in Midland, Michigan, United States, and a subsidiary of Dow Inc. The company is among the three largest chemical producers in the world. Dow manu ...
), killed at least 3787 people and injured from 150,000 to 600,000. The United Kingdom suffered its worst air pollution event when the December 4
Great Smog The Great Smog of London, or Great Smog of 1952, was a severe air pollution Air pollution is the presence of substances in the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ...
of 1952 formed over
London London is the capital Capital most commonly refers to: * Capital letter Letter case (or just case) is the distinction between the letters that are in larger uppercase or capitals (or more formally ''majuscule'') and smaller lowerc ...

London
. In six days more than 4,000 died and more recent estimates put the figure at nearer 12,000. An accidental leak of
anthrax Anthrax is an infection caused by the bacterium ''Bacillus anthracis''. It can occur in four forms: skin, lungs, intestinal, and injection. Symptom onset occurs between one day to over two months after the infection is contracted. The skin form ...

anthrax
spores from a
biological warfare Biological warfare, also known as germ warfare, is the use of Toxin#Biotoxins, biological toxins or Pathogen, infectious agents such as bacteria, viruses, insects, and Fungus, fungi with the intent to kill, harm or incapacitate humans, animal ...
laboratory in the former
USSR The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a socialist state that spanned Eurasia during its existence from 1922 to 1991. It was nominally a Federation, federal union of multiple national Republics of ...

USSR
in 1979 near Sverdlovsk is believed to have caused at least 64 deaths. The worst single incident of air pollution to occur in the US occurred in
Donora, Pennsylvania Donora is a borough A borough is an administrative division in various English language, English-speaking countries. In principle, the term ''borough'' designates a self-governing walled town, although in practice, official use of the term va ...
in late October, 1948, when 20 people died and over 7,000 were injured.


Alternatives to pollution

There are now practical alternatives to the principal causes of air pollution: * 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.
Aviation biofuel An aviation biofuel or bio-jet-fuel or bio-aviation fuel (BAF) is a biofuel used to power aircraft An aircraft is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by ...
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). * Ship propulsion and idling can be switched to much cleaner fuels like natural gas. (Ideally a
renewable source Renewable energy is useful energy that is collected from renewable resources, which are naturally replenished on a Orders of magnitude (time), human timescale, including carbon neutral sources like sunlight, wind power, wind, rain, tidal power ...
but not practical yet) * Combustion of fossil fuels for space heating can be replaced by using
ground source heat pumps A geothermal heat pump (GHP) or ground source heat pump (GSHP) is a type of heat pump A heat pump is a device used to warm and sometimes also cool buildings by transferring thermal energy from a cooler space to a warmer space using the refrig ...
and
seasonal thermal energy storage A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of Earth's orbit around the Sun and Earth's axial tilt relative to the ecliptic plane. I ...
. * Electric power generation from burning fossil fuels can be replaced by power generation from nuclear and renewables. For poor nations, heating and home stoves that contribute much to regional air pollution can be replaced by a much cleaner fossil fuel like natural gas, or ideally, renewables. * 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. *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. * can be utilized in poor nations where
slash and burn Slash-and-burn agriculture is a farming method that involves the cutting and burning of plants in a forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating ...
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 it down in a large modern biodigester, producing much needed energy to use. * 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.


Reduction efforts

Various pollution control technologies and strategies are available to reduce air pollution.Fensterstock, Ketcham and Walsh, The Relationship of Land Use and Transportation Planning to Air Quality Management, Ed. George Hagevik, May 1972. At its most basic level,
land-use planning Land use planning is the process of regulating the use of land by a central authority. Usually, this is done to promote more desirable social and environmental outcomes as well as a more efficient use of resources. More specifically, the goals o ...
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. Because a large share of air pollution is caused by combustion of
fossil fuels A fossil fuel is a hydrocarbon In organic chemistry, a hydrocarbon is an organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen che ...
such as
coal Coal is a combustible , Germany ) , image_map = , map_caption = , map_width = 250px , capital = Berlin , coordinates = , largest_city = capital , languages_type = Official language , languages = German language, German , ...

coal
and
oil An oil is any nonpolar chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can b ...

oil
, the reduction of these fuels can reduce air pollution drastically. Most effective is the switch to clean power sources such as
wind power Wind power or wind energy is the use of wind turbine A wind turbine is a device that converts Religious conversion is the adoption of a set of beliefs identified with one particular religious denomination A religious denomination ...

wind power
,
solar power Solar power is the conversion of renewable energy Renewable energy is energy that is collected from renewable resource File:Global Vegetation.jpg, Global vegetation A renewable resource, also known as a flow resource, is a natural re ...

solar power
,
hydro power Hydropower (from el, ὕδωρ, "water"), also known as water power, is the use of falling or fast-running water to produce electricity or to power machines. This is achieved by converting the water's kinetic energy In physics, the kineti ...
which don't cause air pollution. Efforts to reduce pollution from mobile sources includes primary regulation (many developing countries have permissive regulations), expanding regulation to new sources (such as cruise and transport ships, farm equipment, and small gas-powered equipment such as
string trimmer A string trimmer, also called a weed eater, weed whacker, weedwacker, weed whip, line trimmer, brush cutter, whipper snipper (in Australia, Canada, and South Africa) or strimmer (in the UK and Ireland), is a garden tool A garden tool is any on ...
s,
chainsaw A chainsaw (or chain saw) is a portable gasoline-, electric-, or battery-powered saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. It is used in activities such as tree felling, limbing, Log bucking, bucki ...
s, and
snowmobiles A snowmobile, also known as a motor sled, motor sledge, skimobile, snow scooter, Ski-Doo, or snowmachine, is a motorized vehicle designed for winter travel and recreation on snow Snow comprises individual ice crystals that grow while sus ...
), increased fuel efficiency (such as through the use of
hybrid vehicle A hybrid vehicle is one that uses two or more distinct types of power, such as submarines that use diesel when surfaced and batteries when submerged. Other means to store energy include pressurized fluid in hydraulic hybridHydraulic hybrid veh ...
s), conversion to cleaner fuels or conversion to
electric vehicle An electric vehicle (EV) is a vehicle A vehicle (from la, vehiculum) is a machine A machine is a man-made device that uses power to apply forces and control movement to perform an action. Machines can be driven by animals and peopl ...

electric vehicle
s.
Titanium dioxide Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical ...
has been researched for its ability to reduce air pollution.
Ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, ...

Ultraviolet
light will release free electrons from material, thereby creating free radicals, which break up VOCs and NOx gases. One form is
superhydrophilicSuperhydrophilicity refers to the phenomenon of excess hydrophilicity, or attraction to water; in superhydrophilic materials, the contact angle of water is equal to zero degrees. This effect was discovered in 1995 by the Research Institute of Toto Lt ...
. In 2014, Prof. Tony Ryan and Prof. Simon Armitage of
University of Sheffield , mottoeng = To discover the causes of things , established = – University of SheffieldPredecessor institutions: – Sheffield Medical School , mottoeng = Art is long, life is short , established = 1828 – Sheffield School ...
prepared a 10 meter by 20 meter-sized poster coated with microscopic, pollution-eating nanoparticles of titanium dioxide. Placed on a building, this giant poster can absorb the toxic emission from around 20 cars each day. A very effective means to reduce air pollution is the transition to
renewable energy Renewable energy is energy that is collected from renewable resource File:Global Vegetation.jpg, Global vegetation A renewable resource, also known as a flow resource, is a natural resource which will replenish to replace the portion resou ...
. According to a study published in
Energy and Environmental Science In physics, energy is the physical quantity, quantitative physical property, property that must be #Energy transfer, transferred to an Physical body, object in order to perform Work (thermodynamics), work on, or to heat, the object.The second ...
in 2015 the switch to
100% renewable energy Comparing trends in worldwide energy use, the growth of renewable energy to 2015 is the green line 100% renewable energy is where all energy use is sourced from renewable energy sources. The endeavor to use 100% renewable energy for electr ...
in the United States would eliminate about 62,000 premature mortalities per year and about 42,000 in 2050, if no biomass were used. This would save about $600 billion in health costs a year due to reduced air pollution in 2050, or about 3.6% of the 2014 U.S. gross domestic product. There is limited evidence that efforts to reduce particulate matter in the air can result in better health in Africa, the Middle East, Eastern Europe, Central Asia, and Southeast Asia.


Control devices

The following items are commonly used as pollution control devices in industry and transportation. They can either destroy
contaminant Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc. Nuances of contamination ...
s or remove them from an exhaust stream before it is emitted into the atmosphere. * Particulate control ** Mechanical collectors ( dust cyclones, multicyclones) **
Electrostatic precipitator An electrostatic precipitator (ESP) is a filterless device that removes fine particles, like dust and smoke, from a flowing gas using the force of an induced electrostatic charge minimally impeding the flow of gases through the unit. In contra ...

Electrostatic precipitator
s An electrostatic precipitator (ESP), or electrostatic air cleaner is a particulate collection device that removes particles from a flowing gas (such as air), using the force of an induced electrostatic charge. Electrostatic precipitators are highly efficient filtration devices that minimally impede the flow of gases through the device, and can easily remove fine particulates such as dust and smoke from the air stream. ** Baghouses Designed to handle heavy dust loads, a dust collector consists of a blower, dust filter, a filter-cleaning system, and a dust receptacle or dust removal system (distinguished from air cleaners which utilize disposable filters to remove the dust). ** Wet scrubber is a form of pollution control technology. The term describes a variety of devices that use pollutants from a furnace flue gas or from other gas streams. In a wet scrubber, the polluted gas stream is brought into contact with the scrubbing liquid, by spraying it with the liquid, by forcing it through a pool of liquid, or by some other contact method, so as to remove the pollutants. *
Scrubber Scrubber systems (e.g. chemical scrubbers, gas scrubbers) are a diverse group of air pollution Air pollution is the presence of substances in the atmosphere that are harmful to the health of human Humans (''Homo sapiens'') are the most ...
s ** Baffle spray scrubber ** Cyclonic spray scrubber **
Ejector venturi scrubber Image:ejectorventuri.jpg, 275px, Figure 1 - Ejector venturi scrubber An ejector or jet venturi scrubber is an industrial pollution control device, usually installed on the exhaust flue gas stacks of large furnaces, but may also be used on any number ...
** Mechanically aided scrubber **
Spray tower A spray tower (or spray column or spray chamber) is gas-liquid contactor used to achieve mass Mass is both a property Property (''latin: Res Privata'') in the Abstract and concrete, abstract is what belongs to or with something, whethe ...
**
Wet scrubber The term wet scrubber describes a variety of devices that remove pollutants from a furnace flue gas or from other gas streams. In a wet scrubber, the polluted gas stream is brought into contact with the scrubbing liquid, by spraying it with the ...

Wet scrubber
*
NOx control In atmospheric chemistry, is a generic term for the nitrogen oxides that are most relevant for air pollution, namely nitric oxide (NO) and nitrogen dioxide (). These gases contribute to the formation of smog and acid rain, as well as aff ...
** Low NOx burners **
Selective catalytic reduction Selective catalytic reduction (SCR) is a means of converting nitrogen oxideNitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds: Charge-neutral *Nitric oxide (NO), nitrogen(II) oxide, or nitrogen m ...
(SCR) ** Selective non-catalytic reduction (SNCR) ** **
Exhaust gas recirculation Image:SaabHengine.jpg, 300px, EGR valve the top of box on top of the inlet manifold of a Saab H engine in a 1987 Saab 90 In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide () emissions reduction technique used in p ...

Exhaust gas recirculation
**
Catalytic converter A catalytic converter is an exhaust emission control device that reduces toxic gases and pollutants in exhaust gas from an internal combustion engine An internal combustion engine (ICE) is a heat engine in which the combustion of a fuel o ...

Catalytic converter
(also for VOC control) * VOC abatement ** , using
activated carbon Activated carbon, also called activated charcoal, is a form of carbon Carbon (from la, carbo "coal") is a chemical element with the Symbol (chemistry), symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—making f ...

activated carbon
, such as Fluidized Bed Concentrator **
Flares A flare, also sometimes called a fusée or bengala in some latin-speaking countries, is a type of pyrotechnic s used in the entertainment industry Pyrotechnics is the science and craft of creating such things as fireworks Fireworks are ...
** Thermal oxidizers **
Catalytic converter A catalytic converter is an exhaust emission control device that reduces toxic gases and pollutants in exhaust gas from an internal combustion engine An internal combustion engine (ICE) is a heat engine in which the combustion of a fuel o ...

Catalytic converter
s **
Biofilter composting plant biofilter mound - note sprinkler visible front right to maintain proper moisture level for optimum functioning Biofiltration is a pollution control Pollution is the introduction of contaminants into the natural environment t ...
s ** **
Cryogenic A medium-sized dewar is being filled with liquid nitrogen by a larger cryogenic storage tank In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motio ...
condensers ** Vapor recovery systems *
Acid GasAcid gas is a particular typology of natural gas Natural gas (also called fossil gas; sometimes just gas) is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher a ...
/ SO2 control **
Wet scrubber The term wet scrubber describes a variety of devices that remove pollutants from a furnace flue gas or from other gas streams. In a wet scrubber, the polluted gas stream is brought into contact with the scrubbing liquid, by spraying it with the ...

Wet scrubber
s ** Dry scrubbers **
Flue-gas desulfurization Flue-gas desulfurization (FGD) is a set of technologies used to remove sulfur dioxide () from Flue gas, exhaust flue gases of fossil-fuel power plants, and from the emissions of other sulfur oxide emitting processes such as waste incineration. M ...

Flue-gas desulfurization
*
Mercury Mercury usually refers to: * Mercury (planet) Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman g ...

Mercury
control ** Sorbent Injection Technology ** Electro-Catalytic Oxidation (ECO) ** K-Fuel *
Dioxin Dioxin may refer to: *1,2-Dioxin or 1,4-Dioxin, two unsaturated Heterocyclic#6-Membered rings, heterocyclic 6-membered rings where two carbon atoms have been replaced by oxygen atoms, giving the chemical formula#Molecular formula, molecular formul ...
and
furan Furan is a heterocyclic 125px, Pyridine, a heterocyclic compound A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different chemical element, elements as members of its ring(s). Heterocyclic chemis ...

furan
control * Miscellaneous associated equipment ** Source capturing systems ** Continuous emissions monitoring systems (CEMS)


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 The U.S. National Ambient Air Quality Standards (NAAQS, pronounced \'naks\) are limits on atmospheric concentration of six air pollution, pollutants that cause smog, acid rain, and other health hazards. Established by the United States Environmental ...
and E.U
Air Quality Directive
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 An air quality index (AQI) is used by government agencies A government or state agency, sometimes an appointed commission, is a permanent or semi-permanent organization in the machinery of government that is responsible for the oversight and admi ...

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 or (AQHI). 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 Air Quality Health Index or "AQHI" is a federal program jointly coordinated by
Health Canada Health Canada (HC; french: Santé Canada, SC)Health Canada is the applied title under the Federal Identity Program on the Remote Manipulator System, Canadarm The Federal Identity Program (FIP) is the Government of Canada's corporate identity pro ...
and
Environment Canada Environment and Climate Change Canada (ECCC; french: Environnement et Changement climatique Canada)Environment and Climate Change Canada is the applied title under the Federal Identity Program on the Remote Manipulator System, Canadarm The Fede ...
. However, the AQHI program would not be possible without the commitment and support of the provinces, municipalities and NGOs. From air quality monitoring to health risk communication and community engagement, local partners are responsible for the vast majority of work related to AQHI implementation. The AQHI provides a number from 1 to 10+ to indicate the level of health risk associated with local air quality. Occasionally, when the amount of air pollution is abnormally high, the number may exceed 10. The AQHI provides a local air quality current value as well as a local air quality maximums forecast for today, tonight and tomorrow and provides associated health advice. 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. The measurement is based on the observed relationship of nitrogen dioxide (NO2), ground-level ozone (O3) and particulates (PM2.5) 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 Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lower ...

ozone
, and
nitrogen dioxide Nitrogen dioxide is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by hav ...

nitrogen dioxide
(NO2), as well as
sulfur dioxide Sulfur dioxide (-recommended spelling) or sulphur dioxide (traditional ) is the with the formula . It is a responsible for the smell of burnt es. It is released naturally by and is produced as a by-product of extraction and the burning of ...
(SO2), and
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom. It is the simplest molecule of the oxocarbon family. In ...

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 Pollen is a powdery substance consisting of pollen grains which are Sporophyte, microsporophytes of spermatophyta, seed plants, which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the ga ...

pollen
, dust, heat or humidity.


Germany

TA LuftGermany has an air pollution control regulation titled "Technical Instructions on Air Quality Control" (''Technische Anleitung zur Reinhaltung der Luft'') and commonly referred to as the ''TA Luft''. The first version of the ''TA Luft'' was establis ...
is the German air quality regulation.


Hotspots

Air pollution hotspots are areas where air pollution emissions expose individuals to increased negative health effects. 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 Respiratory diseases, or lung diseases, are pathology, pathological conditions affecting the organs and tissues that make gas exchange difficult in Breathing, air-breathing animals. They include conditions of the respiratory tract including the tr ...
, childhood
asthma Asthma is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank Consolidation", M. E. Sharpe, Inc., 2002 based in Greenwich, ...

asthma
,
cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumor A benign tumor is a mass of cells Cell most often refers to: * Cell (biolo ...

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. 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. Hazardous land uses (toxic storage and disposal facilities, manufacturing facilities, major roadways) tend to be located where property values and income levels are low. Low socioeconomic status can be a proxy for other kinds of
social vulnerability In its broadest sense, social vulnerability is one dimension of vulnerability Vulnerability refers to the inability (of a system or a unit) to withstand the effects of a hostile environment. A window of vulnerability (WOV) is a time frame within ...
, including race, a lack of ability to influence regulation and a lack of ability to move to neighborhoods with less environmental pollution. These communities bear a disproportionate burden of environmental pollution and are more likely to face health risks such as cancer or asthma. Studies show that patterns in race and income disparities not only indicate a higher exposure to pollution but also higher risk of adverse health outcomes. Communities characterized by low socioeconomic status and racial minorities can be more vulnerable to cumulative adverse health impacts resulting from elevated exposure to pollutants than more privileged communities. Blacks and Latinos generally face more pollution than whites and Asians, and low-income communities bear a higher burden of risk than affluent ones. Racial discrepancies are particularly distinct in suburban areas of the
Southern United States The Southern United States, also referred to as the Southern States, the American South, Dixie, the Southland, or simply the South, is a geographic and cultural region In geography Geography (from Greek: , ''geographia'', literally ...
and metropolitan areas of the
Midwestern The midwestern United States, often referred to simply as the Midwest, is one of four census regions of the United States Census Bureau The United States Census Bureau (USCB), officially the Bureau of the Census, is a principal agency of ...
and
Western United States The Western United States (also called the American West, the Far West, and the West) is the region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of the ...
. Residents in public housing, who are generally low-income and cannot move to healthier neighborhoods, are highly affected by nearby refineries and chemical plants.


Cities

Air pollution is usually concentrated in densely populated metropolitan areas, especially in developing countries where environmental regulations are relatively lax or nonexistent. However, even populated areas in developed countries attain unhealthy levels of pollution, with
Los Angeles Los Angeles ( ; xgf, Tovaangar; es, Los Ángeles, , ), commonly referred to by the initialism An acronym is a word In linguistics, a word of a spoken language can be defined as the smallest sequence of phonemes that can be u ...

Los Angeles
and
Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg , map_caption = The te ...

Rome
being two examples. Between 2002 and 2011 the incidence of lung cancer in
Beijing Beijing ( ), as Peking ( ), is the of the . It is the world's , with over 21 million residents within an of 16,410.5 km2 (6336 sq. mi.). It is located in , and is governed as a under the direct administration of the with .Figures ...

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.


Governing urban air pollution

In
Europe Europe is a continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of scienc ...

Europe
, Council Directive 96/62/EC on ambient air quality assessment and management provides a common strategy against which
member states A member state is a state that is a member of an international organization An international organization (also known as an international institution or intergovernmental organization) is a stable set of norms and rules meant to govern the be ...
can "set objectives for ambient air quality in order to avoid, prevent or reduce harmful effects on human health and the environment ... and improve air quality where it is unsatisfactory". On 25 July 2008 in the case Dieter Janecek v Freistaat Bayern CURIA, the
European Court of Justice European, or Europeans, may refer to: In general * ''European'', an adjective referring to something of, from, or related to Europe ** Ethnic groups in Europe ** Demographics of Europe ** European cuisine, the cuisines of Europe and other Western ...

European Court of Justice
ruled that under this directive 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. This important
case law Case law is the collection of past legal decisions written by courts and similar tribunal A tribunal, generally, is any person or institution with authority to judge, adjudicate on, or determine claims or disputes—whether or not it is calle ...
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
European Commission The European Commission (EC) is the executive branch The executive is the branch of government exercising authority in and holding Moral responsibility, responsibility for the governance of a State (polity), state. The executive executes a ...

European Commission
(EC) threatened the UK with legal action against the successive breaching of
PM10 Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM), or suspended particulate matter (SPM) – are microscopic The microscopic scale (from , ''mikrós'', "small" and σκοπ ...
limit values. The UK government has identified that if fines are imposed, they could cost the nation upwards of £300 million per year. In March 2011, the
Greater London Built-up Area The Greater London Built-up Area, or Greater London Urban Area, is a conurbation A conurbation is a region comprising a number of metropolises, cities, large towns, and other urban areas that, through population growth and physical expansion, ha ...

Greater London Built-up Area
remains the only UK region in breach of the EC's limit values, and has been given 3 months to implement an emergency action plan aimed at meeting the EU Air Quality Directive. The City of London has dangerous levels of PM10 concentrations, estimated to cause 3000 deaths per year within the city. As well as the threat of EU fines, in 2010 it was threatened with legal action for scrapping the western
congestion charge Congestion pricing or congestion charges is a system of surcharging users of public goods that are subject to congestion through excess demand In economics Economics () is the social science that studies how people interact with value ...
zone, which is claimed to have led to an increase in air pollution levels. In response to these charges,
Boris Johnson Alexander Boris de Pfeffel Johnson (; born 19 June 1964) is a British politician and writer serving as Prime Minister of the United Kingdom The prime minister of the United Kingdom is the head of government The head of government ...

Boris Johnson
,
Mayor of London The mayor of London is the chief executive of the Greater London Authority The Greater London Authority (GLA), colloquially known by the metonym "City Hall", is the Devolution in the United Kingdom, devolved Regions of England, regional ...
, has criticised the current need for European cities to communicate with Europe through their nation state's
central government A central government is the government A government is the system or group of people governing an organized community, generally a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthl ...
, 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. 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, allowing sub-national actors including cities and
regions In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and phenomena of the Earth and planets. The first person to use the wor ...

regions
to partake in air pollution control as independent actors. Particularly promising at present are global city partnerships. These can be built into networks, for example the
C40 Cities Climate Leadership Group The C40 Cities Climate Leadership Group is a group of 97 cities around the world that represents one twelfth of the world's population and one quarter of the global economy. Created and led by cities, C40 is focused on tackling climate change and ...
, 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. The C40 has been identified as 'governance from the middle' and is an alternative to intergovernmental policy. 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". 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.


Projections

According to one projection, by 2030 half of the world's pollution emissions could be generated by
Africa Africa is the world's second-largest and second-most populous continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', ...

Africa
. 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 Population growth is the increase in the number of people in a population Population typically refers the number of people in a single area whether it be a city or town, region, country, or the world. Governments typically quantify the size ...
.


See also

*
Air pollutant concentrationsAir pollutant concentrations, as measured or as calculated by air pollution dispersion modeling, must often be converted or corrected to be expressed as required by the regulations issued by various governmental agencies. Regulations that define an ...
* Air stagnation *
ASEAN Agreement on Transboundary Haze Pollution was barely visible. 's Downtown Core The Downtown Core is the historical and downtown centre of the city-state of Singapore and the main commercial area in Singapore excluding reclaimed lands with many integrated resorts such as the Marina B ...
*
Asian brown cloud The Indian Ocean brown cloud or Asian brown cloud is a layer of air pollution Air pollution is the presence of substances in the atmosphere that are harmful to the health of human Humans (''Homo sapiens'') are the most populous and wid ...
*
Atmospheric chemistry Atmospheric chemistry is a branch of in which the of the and that of other planets is studied. It is a of research and draws on , , , , , and and other disciplines. Research is increasingly connected with other areas of study such as . The ...
* Beehive burner * BenMAP * Best Available Control Technology * Critical load * Emission standard * Emissions & Generation Resource Integrated Database * Environmental agreement * Flue-gas emissions from fossil-fuel combustion * Global Atmosphere Watch * Global dimming *
Great Smog The Great Smog of London, or Great Smog of 1952, was a severe air pollution Air pollution is the presence of substances in the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ...
of London * Haze * Health Effects Institute (HEI) * Indicator value * Intake fraction * International Agency for Research on Cancer * Kyoto Protocol * Light water reactor sustainability * List of accidents and disasters by death toll#Smog, List of smogs by death toll * Lowest Achievable Emissions Rate *
Montreal Protocol The largest Antarctic ozone hole recorded as of September 2006 The Montreal Protocol is an international treaty A treaty is a formal, legally binding written agreement between actors in international law International law, also known ...
* NASA Clean Air Study * Non-exhaust emissions * Organic molecular tracers * Particulate matter sampler * Polluter pays principle * Regulation of greenhouse gases under the Clean Air Act * Tire fire


References


Further reading

* Brimblecombe, Peter. ''The Big Smoke: A History of Air Pollution in London Since Medieval Times'' (Methuen, 1987) * Brimblecombe, Peter. "History of air pollution." in ''Composition, Chemistry and Climate of the Atmosphere'' (Van Nostrand Reinhold (1995): 1–18 * * 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#
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, 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. * Mingle, Jonathan, "Our Lethal Air" [review of Gary Fuller, ''The Invisible Killer...''; Beth Gardiner, ''Choked...''; Tim Smedley, ''Clearing the Air...''; U.S. Environmental Protection Agency, ''Integrated Science Assessment for Particulate Matter (External Review Draft, 2018)''; and Chartered Clean Air Scientific Advisory Committee, ''Letter to EPA Administrator on the EPA's Integrated Science Assessment for Particulate Matter, April 11, 2019''], ''The New York Review of Books'', vol. LXVI, no. 14 (26 September 2019), pp. 64–66, 68. "Today, 91 percent of people worldwide live in areas where air pollution levels exceed the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations United Nations Specialized Agencies are autonomous organizations working with the United Nations and each other through the co-ordinating machinery of the Unit ...
's recommended limits.... [T]here is no safe level of exposure to fine
particulate matter upright=1.7, Movie map of distribution of aerosol particles, based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite: * Green areas show aerosol plumes dominated by larger particles. * Red area ...
.... Most of these fine particles are a by-product of... burning...
coal Coal is a combustible , Germany ) , image_map = , map_caption = , map_width = 250px , capital = Berlin , coordinates = , largest_city = capital , languages_type = Official language , languages = German language, German , ...

coal
, gasoline, Diesel fuel, diesel, wood, Garbage, trash... These particles can get past the defenses of our upper airways to penetrate deep into our
lung The lungs are the primary organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tissues can be broadly categorized as parenchyma ...

lung
s and reach the Pulmonary alveolus, alveoli... From there, they cross into the bloodstream and spread throughout the body. They can travel through the nose, up the olfactory nerve, and lodge... in the brain. They can form deposits on the lining of arteries, constricting blood vessels and raising the likelihood of...
stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Di ...

stroke
s and heart attacks. [T]hey exacerbate respiratory illnesses like
asthma Asthma is a long-term Long-Term Capital Management L.P. (LTCM) was a hedge fund''A financial History of the United States Volume II: 1970–2001'', Jerry W. Markham, Chapter 5: "Bank Consolidation", M. E. Sharpe, Inc., 2002 based in Greenwich, ...

asthma
and chronic obstructive pulmonary disease... There's... evidence linking air pollution exposure to an increased risk of Alzheimer's disease, 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


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
International Conference on Urban Air Quality
.
UNEP Urban Issues


* [https://www.who.int/phe/health_topics/outdoorair/databases/en/index.html Database: outdoor air pollution in cities] from the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations United Nations Specialized Agencies are autonomous organizations working with the United Nations and each other through the co-ordinating machinery of the Unit ...

World Health Organization Fact Sheet on Air quality and health

Centre for Research on Energy and Clean Air


UK Committee on the Medical Effects of Air Pollution, 2010.
Ozone Pollution
at EPA.gov {{DEFAULTSORT:Air Pollution Air pollution, Climate forcing Articles containing video clips