Air pollution is the introduction of chemicals, particulate matter, or
biological materialA biomolecule is any molecule that is produced by a living organism, including large polymeric molecules such as proteins, polysaccharides, lipids, and nucleic acids as well as small molecules such as primary metabolites, secondary metabolites, and natural products...
s that cause harm or discomfort to humans or other living organisms, or cause damage to the
natural environmentThe natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species....
or
built environmentThe term built environment refers to the human-made surroundings that provide the setting for human activity, ranging in scale from personal shelter and buildings to neighborhoods and cities that can often include their supporting infrastructure, such as water supply or energy networks.The built...
, into the
atmosphereThe atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
.
The atmosphere is a complex dynamic natural gaseous system that is essential to support life on planet
EarthEarth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
.
StratosphericThe stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler...
ozone depletionOzone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about 4% per decade in the total volume of ozone in Earth's stratosphere , and a much larger springtime decrease in stratospheric ozone over Earth's polar regions. The latter phenomenon...
due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems.
Indoor air pollution and urban air quality are listed as two of the world's worst pollution problems in the 2008
Blacksmith InstituteFounded in 1999, Blacksmith Institute is an international non-for-profit organization dedicated to eliminating life-threatening pollution in the developing world. Blacksmith identifies and cleans up the world's worst polluted places, focusing on communities where children are most at risk. Based in...
World's Worst Polluted Places report.
Pollutants
A substance in the air that can cause harm to humans and the environment is known as an air pollutant. Pollutants can be in the form of solid particles, liquid droplets, or gases. In addition, they may be natural or man-made.
Pollutants can be classified as primary or secondary. Usually, primary pollutants are directly emitted from a process, such as ash from a volcanic eruption, the
carbon monoxideCarbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
gas from a motor vehicle exhaust or sulfur dioxide released from factories. Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone — one of the many secondary pollutants that make up photochemical smog. Some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants.
Major primary pollutants produced by human activity include:
- Sulfur oxide
Sulfur oxide refers to one or more of the following:* Lower sulfur oxides * Sulfur monoxide * Sulfur dioxide * Sulfur trioxide *Higher sulfur oxides Sulfur oxide (SOx) refers to one or more of the following:* Lower sulfur oxides (SnO, S7O2 and S6O2)* Sulfur monoxide (SO)* Sulfur dioxide (SO2)*...
s (SOx) - especially sulphur dioxide, a chemical compound with the formula SO2. SO2 is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulphur compounds, 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.[2] 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 can refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:* Nitric oxide, also known as nitrogen monoxide, , nitrogen oxide* Nitrogen dioxide , nitrogen oxide...
s (NOx) - especially nitrogen dioxideNitrogen dioxide is the chemical compound with the formula it is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent...
are emitted from high temperature combustion. Can be seen as the brown haze dome above or plumeIn hydrodynamics, a plume is a column of one fluid or gas moving through another. Several effects control the motion of the fluid, including momentum, diffusion, and buoyancy...
downwind of cities. Nitrogen dioxide is the chemical compound with the formula NO2. It is one of the several nitrogen oxides. This reddish-brown toxic gas has a characteristic sharp, biting odor. NO2 is one of the most prominent air pollutants.
- Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
- is a colourless, odorless, non-irritating but very poisonous gas. It is a product by incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of carbon monoxide.
- Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
(CO2) - a colourless, odorless, non-toxic greenhouse gasA greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
associated with ocean acidificationOcean acidification is the name given to the ongoing decrease in the pH and increase in acidity of the Earth's oceans, caused by the uptake of anthropogenic carbon dioxide from the atmosphere....
, emitted from sources such as combustion, cement production, and respirationCellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate , and then release waste products. The reactions involved in respiration are catabolic reactions that involve...
- Volatile organic compounds - VOCs are an important outdoor air pollutant. In this field they are often divided into the separate categories of methane (CH4) and non-methane (NMVOCs). Methane is an extremely efficient greenhouse gas which contributes to enhanced global warming. Other hydrocarbon VOCs are also significant greenhouse gases via their role in creating ozone and in prolonging the life of methane in the atmosphere, although the effect varies depending on local air quality. Within the NMVOCs, the aromatic compounds benzene, toluene and xylene are suspected carcinogens and may lead to leukemia through prolonged exposure. 1,3-butadiene is another dangerous compound which is often associated with industrial uses.
- Particulate matter - Particulates, alternatively referred to as particulate matter (PM) or fine particles, are tiny particles of solid or liquid suspended in a gas. In contrast, aerosol refers to particles and the gas together. Sources of particulate matter can be man made or natural. 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 over the globe, anthropogenic aerosols—those made by human activities—currently account for about 10 percent of the total amount of aerosols in 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.
- Persistent free radicals connected to airborne fine particles could cause cardiopulmonary disease.
- Toxic metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
s, such as leadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, cadmiumCadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
and copperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
.
- Chlorofluorocarbons (CFCs) - harmful to the ozone layer
The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone . This layer absorbs 97–99% of the Sun's high frequency ultraviolet light, which is potentially damaging to the life forms on Earth...
emitted from products currently banned from use.
- Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
(NH3) - emitted from agricultural processes. 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.
- Odor
An odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also commonly called scents, which can refer to both pleasant and unpleasant odors...
s — such as from garbage, sewage, and industrial processes
- Radioactive pollutants - produced by nuclear explosions, war explosives, and natural processes such as the radioactive decay
Radioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
of radonRadon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the decay product of uranium or thorium. Its most stable isotope, 222Rn, has a half-life of 3.8 days...
.
Secondary pollutants include:
- Particulate matter formed from gaseous primary pollutants and compounds in photochemical smog. Smog is a kind of air pollution; the word "smog" is a portmanteau of smoke and fog. 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 light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
light from the sun to form secondary pollutants that also combine with the primary emissions to form photochemical smog.
- Ground level ozone (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 radical and nitrogen dioxide gas. It is a lachrymatory substance....
(PAN) - similarly formed from NOx and VOCs.
Minor air pollutants include:
- A large number of minor hazardous air pollutants. Some of these are regulated in USA under the Clean Air Act
A Clean Air Act is one of a number of pieces of legislation relating to the reduction of airborne contaminants, smog and air pollution in general. The use by governments to enforce clean air standards has contributed to an improvement in human health and longer life spans...
and in Europe under the Air Framework Directive.
- A variety of persistent organic pollutant
thumb|right|275px|State parties to the Stockholm Convention on Persistent Organic PollutantsPersistent organic pollutants are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes...
s, which can attach to particulate matter.
Persistent organic pollutants (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, bioaccumulate in human and animal tissue, biomagnify in food chains, and to have potential significant impacts on human health and the environment.
Sources
Sources of air pollution refer to the various locations, activities or factors which are
responsible for the releasing of pollutants into the atmosphere. These sources can be classified into two major categories which are:
Anthropogenic sources (human activity) mostly related to burning different kinds of
fuelFuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
- "Stationary Sources" include smoke stacks of power plants, manufacturing facilities (factories) and waste incinerators, as well as furnaces and other types of fuel-burning heating devices
- "Mobile Sources" include motor vehicles
Roadway air dispersion modeling is the study of air pollutant transport from a roadway or other linear emitter. Computer models are required to conduct this analysis, because of the complex variables involved, including vehicle emissions, vehicle speed, meteorology, and terrain geometry...
, marine vessels, aircraft and the effect of sound etc.
- Chemicals, dust and controlled burn
Controlled or prescribed burning, also known as hazard reduction burning or Swailing 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...
practices in agriculture and forestry 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.
- Fumes from paint
Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
, hair sprayHair spray is a common cosmetic product that is sprayed onto hair to keep it stiff or in a certain style...
, varnishVarnish is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. Varnish is traditionally a combination of a drying oil, a resin, and a thinner or solvent. Varnish finishes are usually glossy but may be designed to produce satin or semi-gloss...
, aerosol sprayAerosol spray is a type of dispensing system which creates an aerosol mist of liquid particles. This is used with a can or bottle that contains a liquid under pressure. When the container's valve is opened, the liquid is forced out of a small hole and emerges as an aerosol or mist...
s and other solvents
- Waste deposition in landfill
A landfill site , is a site for the disposal of waste materials by burial and is the oldest form of waste treatment...
s, which generate methaneMethane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
. Methane is not toxic; however, it 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, such as nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...
s, toxic gases, germ warfare and rocketA rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
ry
Natural sources
- Dust
Dust consists of particles in the atmosphere that arise from various sources such as soil dust lifted up by wind , volcanic eruptions, and pollution...
from natural sources, usually large areas of land with little or no vegetation
- Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
, emittedFlatulence is the expulsion through the rectum of a mixture of gases that are byproducts of the digestion process of mammals and other animals. The medical term for the mixture of gases is flatus, informally known as a fart, or simply gas...
by the digestionDigestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones....
of food by animalAnimals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s, for example cattleCattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
- Radon
Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the decay product of uranium or thorium. Its most stable isotope, 222Rn, has a half-life of 3.8 days...
gas from radioactive decayRadioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
within the Earth's crust. Radon is a colorless, odorless, naturally occurring, radioactive noble gas that is formed from the decay of radium. It is considered to be a health hazard. Radon gas from natural sources can accumulate in buildings, especially in confined areas such as the basement and it is the second most frequent cause of lung cancer, after cigaretteA cigarette is a small roll of finely cut tobacco leaves wrapped in a cylinder of thin paper for smoking. The cigarette is ignited at one end and allowed to smoulder; its smoke is inhaled from the other end, which is held in or to the mouth and in some cases a cigarette holder may be used as well...
smoking
- Smoke
Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires , but may also be used for pest...
and carbon monoxideCarbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
from wildfires
- Vegetation, in some regions, emits environmentally significant amounts of 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.
- Volcanic
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
activity, which produce sulfurSulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
, chlorineChlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
, and ash particulates
Emission factors
Air
pollutantA pollutant is a waste material that pollutes air, water or soil, and is the cause of pollution.Three factors determine the severity of a pollutant: its chemical nature, its concentration and its persistence. Some pollutants are biodegradable and therefore will not persist in the environment in the...
emission factors are representative values that people 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 megagram 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 POPs. Dioxins and furans are two of them and are intentionally created by combustion of organics, like open burning of plastics. The POPs are also endocrine disruptor and can mutate the human genes.
The
United States Environmental Protection AgencyThe U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
has published a compilation of air pollutant emission factors for a multitude of industrial sources. The
United KingdomThe United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
,
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
,
CanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and many other countries have published similar compilations, as well as the
European Environment AgencyEuropean Environment Agency is an agency of the European Union. Its task is to provide sound, independent information on the environment. It is a major information source for those involved in developing, adopting, implementing and evaluating environmental policy, and also the general public...
.
Indoor air quality (IAQ)
A lack of ventilation indoors concentrates air pollution where people often spend the majority of their time. Radon (Rn) gas, a
carcinogenA carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
, is exuded from the Earth in certain locations and trapped inside houses. Building materials including
carpetA carpet is a textile floor covering consisting of an upper layer of "pile" attached to a backing. The pile is generally either made from wool or a manmade fibre such as polypropylene,nylon or polyester and usually consists of twisted tufts which are often heat-treated to maintain their...
ing and
plywoodPlywood is a type of manufactured timber made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can usually be locally manufactured...
emit
formaldehydeFormaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...
(H
2CO) gas. Paint and solvents give off volatile organic compounds (VOCs) as they dry.
LeadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
paint can degenerate into
dustDust consists of particles in the atmosphere that arise from various sources such as soil dust lifted up by wind , volcanic eruptions, and pollution...
and be inhaled. Intentional air pollution is introduced with the use of
air freshenerAir fresheners are consumer products used in homes or commercial products used in restrooms that typically emit fragrance. There are two broad air freshener categories: continuous action and instant action...
s,
incenseIncense is composed of aromatic biotic materials, which release fragrant smoke when burned. The term "incense" refers to the substance itself, rather than to the odor that it produces. It is used in religious ceremonies, ritual purification, aromatherapy, meditation, for creating a mood, and for...
, and other scented items. Controlled wood fires in stoves and
fireplaceA fireplace is an architectural structure to contain a fire for heating and, especially historically, for cooking. A fire is contained in a firebox or firepit; a chimney or other flue allows gas and particulate exhaust to escape...
s can add significant amounts of smoke particulates into the air, inside and out. Indoor pollution fatalities may be caused by using
pesticidePesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s and other chemical sprays indoors without proper ventilation.
Carbon monoxide (CO) poisoning and fatalities are often caused by faulty vents and chimneys, or by the burning of
charcoalCharcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...
indoors. Chronic
carbon monoxide poisoningCarbon monoxide poisoning occurs after enough inhalation of carbon monoxide . Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect...
can result even from poorly adjusted
pilot lightthumb|right|Merker gas fired water heater from the 1930's, with pilot light clearly visible through the aperture in the front cover. The large opening allowed for the manual lighting of the pilot light by a lit match or taper...
s. Traps are built into all domestic
plumbingPlumbing is the system of pipes and drains installed in a building for the distribution of potable drinking water and the removal of waterborne wastes, and the skilled trade of working with pipes, tubing and plumbing fixtures in such systems. A plumber is someone who installs or repairs piping...
to keep sewer gas,
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
, out of interiors. Clothing emits
tetrachloroethyleneTetrachloroethylene, also known under its systematic name tetrachloroethene and many other names, is a chlorocarbon with the formula Cl2C=CCl2. It is a colourless liquid widely used for dry cleaning of fabrics, hence it is sometimes called "dry-cleaning fluid." It has a sweet odor detectable by...
, or other dry cleaning fluids, for days after
dry cleaningDry cleaning is any cleaning process for clothing and textiles using a chemical solvent other than water. The solvent used is typically tetrachloroethylene , abbreviated "perc" in the industry and "dry-cleaning fluid" by the public...
.
Though its use has now been banned in many countries, the extensive use of
asbestosAsbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals...
in industrial and domestic environments in the past has left a potentially very dangerous material in many localities.
AsbestosisAsbestosis is a chronic inflammatory and fibrotic medical condition affecting the parenchymal tissue of the lungs caused by the inhalation and retention of asbestos fibers...
is a chronic
inflammatoryInflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
medical condition affecting the tissue of the
lungThe lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
s. It occurs after long-term, heavy exposure to asbestos from asbestos-containing materials in structures. Sufferers have severe
dyspneaDyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...
(shortness of breath) and are at an increased risk regarding several different types of
lung cancerLung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary...
. 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 the
World Health Organisation (WHO), these may defined as;
asbestosisAsbestosis is a chronic inflammatory and fibrotic medical condition affecting the parenchymal tissue of the lungs caused by the inhalation and retention of asbestos fibers...
, lung cancer, and
Peritoneal MesotheliomaPeritoneal 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 move and work properly.The peritoneum is made of two...
(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.
PetA pet is a household animal kept for companionship and a person's enjoyment, as opposed to wild animals or to livestock, laboratory animals, working animals or sport animals, which are kept for economic or productive reasons. The most popular pets are noted for their loyal or playful...
s produce dander, people produce dust from minute skin flakes and decomposed hair, dust
miteMites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...
s in bedding, carpeting and furniture produce enzymes and micrometre-sized fecal droppings, inhabitants emit methane,
moldMolds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...
forms in walls and generates mycotoxins and spores,
air conditioningAn air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...
systems can incubate
Legionnaires' diseaseLegionellosis is a potentially fatal infectious disease caused by gram negative, aerobic bacteria belonging to the genus Legionella. Over 90% of legionellosis cases are caused by Legionella pneumophila, a ubiquitous aquatic organism that thrives in temperatures between , with an optimum temperature...
and mold, and
houseplantA houseplant is a plant that is grown indoors in places such as residences and offices. Houseplants are commonly grown for decorative purposes, positive psychological effects, or health reasons such as indoor air purification...
s, soil and surrounding gardens can produce
pollenPollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
, 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
The World Health Organization states that 2.4 million people die each year from causes directly attributable to air pollution, with 1.5 million of these deaths attributable to indoor air pollution. "Epidemiological studies suggest that more than 500,000 Americans die each year from cardiopulmonary disease linked to breathing
fine particle air pollutionParticulates – also known as particulate matter , suspended particulate matter , fine particles, and soot – are tiny subdivisions of solid matter suspended in a gas or liquid. In contrast, aerosol refers to particles and/or liquid droplets and the gas together. Sources of particulate matter can be...
. . ." A study by the
University of BirminghamThe University of Birmingham is a British Redbrick university located in the city of Birmingham, England. It received its royal charter in 1900 as a successor to Birmingham Medical School and Mason Science College . Birmingham was the first Redbrick university to gain a charter and thus...
has shown a strong correlation between
pneumoniaPneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
related deaths and air pollution from motor vehicles.
Worldwide more deaths per year are linked to air pollution than to automobile accidents. Published in 2005 suggests that 310,000 Europeans die from air pollution annually. Causes of deaths include aggravated asthma, emphysema, lung and heart diseases, and respiratory allergies. The
US EPAThe U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
estimates that a proposed set of changes in
diesel engineA diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
technology (Tier 2) could result in 12,000 fewer premature mortalities, 15,000 fewer
heart attackMyocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
s, 6,000 fewer emergency room visits by children with
asthmaAsthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...
, and 8,900 fewer respiratory-related hospital admissions each year in the United States. Air pollution is also emerging as a risk factor for stroke, particularly in developing countries where pollutant levels are highest.
The worst short term civilian pollution crisis in
IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
was the 1984
Bhopal DisasterThe Bhopal disaster also known as Bhopal Gas Tragedy was a gas leak incident in India, considered one of the world's worst industrial catastrophes. It occurred on the night of December 2–3, 1984 at the Union Carbide India Limited pesticide plant in Bhopal, Madhya Pradesh, India...
. Leaked industrial vapours from the Union Carbide factory, belonging to Union Carbide, Inc., U.S.A., killed more than 25,000 people outright and injured anywhere from 150,000 to 600,000. The United Kingdom suffered its worst air pollution event when the December 4
Great Smog of 1952The Great Smog of '52 or Big Smoke was a severe air pollution event that affected London, England, during December 1952. A period of cold weather, combined with an anticyclone and windless conditions, collected airborne pollutants mostly from the use of coal to form a thick layer of smog over the...
formed over
LondonLondon is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
. In six days more than 4,000 died, and 8,000 more died within the following months. An accidental leak of
anthraxAnthrax is an acute disease caused by the bacterium Bacillus anthracis. Most forms of the disease are lethal, and it affects both humans and other animals...
spores from a
biological warfareBiological warfare is the use of biological toxins or infectious agents such as bacteria, viruses, and fungi with intent to kill or incapacitate humans, animals or plants as an act of war...
laboratory in the former USSR in 1979 near
SverdlovskYekaterinburg is a major city in the central part of Russia, the administrative center of Sverdlovsk Oblast. Situated on the eastern side of the Ural mountain range, it is the main industrial and cultural center of the Urals Federal District with a population of 1,350,136 , making it Russia's...
is believed to have been the cause of hundreds of civilian deaths. The worst single incident of air pollution to occur in the
United States of AmericaThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
occurred in
DonoraDonora is a borough in Washington County, Pennsylvania, south of Pittsburgh on the Monongahela river. Donora was incorporated in 1901. Donora got its name from a combination of William Donner and Nora Mellon, banker Andrew W. Mellon's wife. Agriculture, coal-mining, steel-making, wire-making, and...
,
PennsylvaniaThe Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
in late October, 1948, when 20 people died and over 7,000 were injured.
The health effects caused by air pollution may include difficulty in breathing, wheezing, coughing and aggravation of existing respiratory and cardiac conditions. These effects can result in increased medication use, increased doctor or emergency room 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, the individual's health status and genetics.
A new economic study of the health impacts and associated costs of air pollution in the
Los Angeles BasinThe Los Angeles Basin is the coastal sediment-filled plain located between the Peninsular and Transverse ranges in southern California in the United States containing the central part of the city of Los Angeles as well as its southern and southeastern suburbs...
and
San Joaquin ValleyThe San Joaquin Valley is the area of the Central Valley of California that lies south of the Sacramento – San Joaquin River Delta in Stockton...
of Southern California shows that more than 3800 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 (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.
This serves as a plausible mechanistic link between the previously described association between particulate matter air pollution and increased cardiovascular morbidity and mortality.
Effects on cystic fibrosis
A study from around the years of 1999 to 2000, by the University of Washington, showed that patients near and around particulate matter air pollution had an increased risk of pulmonary exacerbations and decrease in lung function. Patients were examined before the study for amounts of specific pollutants like
Pseudomonas aeruginosaPseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...
or
Burkholderia cenocepaciaBurkholderia cenocepacia is a species of Gram-negative bacteria that is common in the environment and may cause disease in plants. It is an opportunistic pathogen and human infections are common in patients with cystic fibrosis and chronic granulomatous disease, and are often fatal...
as well as their socioeconomic standing. Participants involved in the study were located in the United States in close proximity to an
Environmental Protection AgencyThe U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
. During the time of the study 117 deaths were associated with air pollution. Many patients in the study lived in or near large metropolitan areas in order to be close to medical help. These same patients had higher level of pollutants found in their system because of more emissions in larger cities. As cystic fibrosis patients already suffer from decreased lung function, everyday pollutants such as smoke, emissions from automobiles, tobacco smoke and improper use of indoor heating devices could further compromise lung function.
Effects on COPD
Chronic obstructive pulmonary diseaseChronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...
(COPD) includes diseases such as
chronic bronchitisChronic bronchitis is a chronic inflammation of the bronchi in the lungs. It is generally considered one of the two forms of chronic obstructive pulmonary disease...
,
emphysemaEmphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...
, and some forms of asthma.
A study conducted in 1960-1961 in the wake of the
Great Smog of 1952The Great Smog of '52 or Big Smoke was a severe air pollution event that affected London, England, during December 1952. A period of cold weather, combined with an anticyclone and windless conditions, collected airborne pollutants mostly from the use of coal to form a thick layer of smog over the...
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 (FEV
1 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.
It is believed that much like
cystic fibrosisCystic fibrosis is a recessive genetic disease affecting most critically the lungs, and also the pancreas, liver, and intestine...
, by living in a more urban environment serious health hazards become more apparent. Studies have shown that in urban areas patients suffer
mucusIn vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
hypersecretion, lower levels of lung function, and more self diagnosis of chronic bronchitis and emphysema.
Effects on children
Cities around the world with high exposure to air pollutants have the possibility of children living within them to develop asthma, pneumonia and other lower respiratory infections as well as a low initial birth rate. Protective measures to ensure the youths' health are being taken in cities such as New Delhi,
IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
where buses now use
compressed natural gasCompressed natural gas is a fossil fuel substitute for gasoline , diesel, or propane/LPG. Although its combustion does produce greenhouse gases, it is a more environmentally clean alternative to those fuels, and it is much safer than other fuels in the event of a spill...
to help eliminate the “pea-soup” smog. Research by the
World Health OrganizationThe World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
shows there is the greatest concentration of particulate matter particles in countries with low economic world power and high poverty and population rates. Examples of these countries include
EgyptEgypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
,
SudanSudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...
,
MongoliaMongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
, and
IndonesiaIndonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
. In the United States, the
Clean Air ActA Clean Air Act is one of a number of pieces of legislation relating to the reduction of airborne contaminants, smog and air pollution in general. The use by governments to enforce clean air standards has contributed to an improvement in human health and longer life spans...
was passed in 1970, however in 2002 at least 146 million Americans were living in
non-attainment areasIn United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards as defined in the Clean Air Act Amendments of 1970 . Nonattainment areas must have and implement a plan to meet the standard, or risk losing some...
—regions in which the concentration of certain air pollutants exceeded federal standards. Those pollutants are known as the criteria pollutants, and include ozone, particulate matter, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. Because children are outdoors more and have higher minute ventilation they are more susceptible to the dangers of air pollution.
Health effects in relatively "clean" areas
Even in the 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 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 a $29 million in annual savings in the Metro Vancouver region in 2010. This finding is based on health valuation of lethal (death) and sub-lethal (illness) effects.
Reduction efforts
There are various air pollution control technologies and
land use planningLand-use planning is the term used for a branch of public policy encompassing various disciplines which seek to order and regulate land use in an efficient and ethical way, thus preventing land-use conflicts. Governments use land-use planning to manage the development of land within their...
strategies available to reduce air pollution. At its most basic level land use planning is likely to involve zoning and transport infrastructure planning. In most developed countries, land use planning is an important part of social policy, ensuring that land is used efficiently for the benefit of the wider economy and population as well as to protect the environment.
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 lawn trimmers,
chainsawA chainsaw is a portable mechanical saw, powered by electricity, compressed air, hydraulic power, or most commonly a two-stroke engine...
s, and snowmobiles), increased fuel efficiency (such as through the use of
hybrid vehicleA hybrid vehicle is a vehicle that uses two or more distinct power sources to move the vehicle. The term most commonly refers to hybrid electric vehicles , which combine an internal combustion engine and one or more electric motors.-Power:...
s), conversion to cleaner fuels (such as bioethanol,
biodieselBiodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....
, or conversion to electric vehicles).
Control devices
The following items are commonly used as pollution control devices by industry or transportation devices. They can either destroy contaminants or remove them from an exhaust stream before it is emitted into the atmosphere.
Legal 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 StandardsThe National Ambient Air Quality Standards are standards established by the United States Environmental Protection Agency under authority of the Clean Air Act that apply for outdoor air throughout the country...
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 IndexAir quality is defined as a measure of the condition of air relative to the requirements of one or more biotic species or to any human need or purpose. Air quality indices are numbers used by government agencies to characterize the quality of the air at a given location...
) 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 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 CanadaHealth Canada is the department of the government of Canada with responsibility for national public health.The current Minister of Health is Leona Aglukkaq, a Conservative Member of Parliament appointed to the position by Prime Minister Stephen Harper.-Branches, regions and agencies:Health Canada...
and
Environment CanadaEnvironment Canada , legally incorporated as the Department of the Environment under the Department of the Environment Act Environment Canada (EC) (French: Environnement Canada), legally incorporated as the Department of the Environment under the Department of the Environment Act Environment...
. 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.
| Risk: |
Low (1-3) |
Moderate (4-6) |
High (7-10) |
Very high (above 10) |
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.
| Health Risk | Air Quality Health Index | ozoneOzone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
, and nitrogen dioxideNitrogen dioxide is the chemical compound with the formula it is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent...
(NO2), as well as sulphur dioxide (SO2), and carbon monoxideCarbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...
(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, pollenPollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
, dust, heat or humidity.
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 AngelesLos Ángeles is the capital of the province of Biobío, in the commune of the same name, in Region VIII , in the center-south of Chile. It is located between the Laja and Biobío rivers. The population is 123,445 inhabitants...
and RomeRome is the capital of Italy and the country's largest and most populated city and comune, with over 2.7 million residents in . The city is located in the central-western portion of the Italian Peninsula, on the Tiber River within the Lazio region of Italy.Rome's history spans two and a half...
being two good examples.
NATA
The National-Scale Air Toxics Assessment (NATA) is EPA's ongoing comprehensive evaluation of air toxics in the U.S. EPA developed the NATA as a state-of-the-science screening tool for State/Local/Tribal Agencies to prioritize pollutants, emission sources and locations of interest for further study in order to gain a better understanding of risks. NATA assessments do not incorporate refined information about emission sources, but rather, use general information about sources to develop estimates of risks which are more likely to overestimate impacts than underestimate them. NATA provides estimates of the risk of cancer and other serious health effects from breathing (inhaling) air toxics in order to inform both national and more localized efforts to identify and prioritize air toxics, emission source types and locations which are of greatest potential concern in terms of contributing to population risk. This in turn helps air pollution experts focus limited analytical resources on areas and or populations where the potential for health risks are highest. Assessments include estimates of cancer and non-cancer health effects based on chronic exposure from outdoor sources, including assessments of non-cancer health effects for Diesel Particulate Matter (PM). Assessments provide a snapshot of the outdoor air quality and the risks to human health that would result if air toxic emissions levels remained unchanged.
Governing Urban Air Pollution – a regional example (London)
In EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Council Directive 96/62/EC on ambient air quality assessment and management provides a common strategy against which member states 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 JusticeThe Court can sit in plenary session, as a Grand Chamber of 13 judges, or in chambers of three or five judges. Plenary sitting are now very rare, and the court mostly sits in chambers of three or five judges...
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 lawIn law, case law is the set of reported judicial decisions of selected appellate courts and other courts of first instance which make new interpretations of the law and, therefore, can be cited as precedents in a process known as stare decisis...
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 CommissionThe European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....
(EC) threatened the UK with legal action against the successive breaching of PM10 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 City of LondonThe City of London is a small area within Greater London, England. It is the historic core of London around which the modern conurbation grew and has held city status since time immemorial. The City’s boundaries have remained almost unchanged since the Middle Ages, and it is now only a tiny part of...
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 zone, which is claimed to have led to an increase in air pollution levels.
In response to these charges, Boris Johnson, Mayor of LondonThe Mayor of London is an elected politician who, along with the London Assembly of 25 members, is accountable for the strategic government of Greater London. Conservative Boris Johnson has held the position since 4 May 2008...
, has criticised the current need for European cities to communicate with Europe through their nation state’s central governmentA central government also known as a national government, union government and in federal states, the federal government, is the government at the level of the nation-state. The structure of central governments varies from institution to institution...
, 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.
In part, this is an attempt to divert blame away from the Mayors office, but it can also 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 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 network, 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.
Carbon dioxide emissions
| Most Polluted World Cities by PM |
Particulate
matter,
μg/m³ (2004) |
City |
| 169 |
Cairo, Egypt |
| 150 |
Delhi, IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
|
| 128 |
Kolkata, IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
(Calcutta) |
| 125 |
Tianjin, ChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
|
| 123 |
Chongqing, ChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
|
| 109 |
Kanpur, IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
|
| 109 |
Lucknow, IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
|
| 104 |
Jakarta, Indonesia |
| 101 |
Shenyang, ChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
|
Total CO2 emissions
| Countries with the highest emissions |
| Country |
Carbon dioxide emissions per
year (106 Tons) (2006) |
Percentage of global total |
Avg. emission
per Km2 of its land (Tons) |
| |
6,103 |
21.5% |
636 |
| |
5,752 |
20.2% |
597 |
| |
1,564 |
5.5% |
91 |
| |
1,510 |
5.3% |
459 |
| |
1293 |
4.6% |
3421 |
| |
805 |
2.8% |
2254 |
| |
568 |
2.0% |
2338 |
| |
544 |
1.9% |
54 |
| |
475 |
1.7% |
4758 |
| |
474 |
1.7% |
1573 |
Per capita CO2 emissions
| Countries with the highest per capita emissions |
| Country |
Carbon dioxide emissions per year
(Tons per person) (2006) |
| |
56.2 |
| |
32.8 |
| |
31.2 |
| |
28.8 |
| |
25.3 |
| |
24.5 |
| |
22.8 |
| |
22.3 |
| |
19 |
| |
18.1 |
Atmospheric dispersion
The basic technology for analyzing air pollution is through the use of a variety of mathematical modelA mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used not only in the natural sciences and engineering disciplines A mathematical model is a...
s for predicting the transport of air pollutants in the lower atmosphere. The principal methodologies are:
- Point source dispersion, used for industrial sources.
- Line source dispersion, used for airport and roadway air dispersion modeling
Roadway air dispersion modeling is the study of air pollutant transport from a roadway or other linear emitter. Computer models are required to conduct this analysis, because of the complex variables involved, including vehicle emissions, vehicle speed, meteorology, and terrain geometry...
- Area source dispersion, used for forest fires or duststorms
- Photochemical models, used to analyze reactive pollutants that form smog
The point source problem is the best understood, since it involves simpler mathematics and has been studied for a long period of time, dating back to about the year 1900. It uses a GaussianGaussian is a computational chemistry software program initially released in 1970 by John Pople and his research group at Carnegie-Mellon University as Gaussian 70. It has been continuously updated since then...
dispersion model for buoyant pollution plumes to forecast the air pollution isoplethsA contour line of a function of two variables is a curve along which the function has a constant value. In cartography, a contour line joins points of equal elevation above a given level, such as mean sea level...
, with consideration given to wind velocity, stack height, emission rate and stability class (a measure of atmospheric turbulenceIn fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic and stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time...
). This model has been extensively validated and calibrated with experimental data for all sorts of atmospheric conditions.
The roadway air dispersion model was developed starting in the late 1950s and early 1960s in response to requirements of the National Environmental Policy ActThe National Environmental Policy Act is a United States environmental law that established a U.S. national policy promoting the enhancement of the environment and also established the President's Council on Environmental Quality ....
and the U.S. Department of Transportation (then known as the Federal Highway Administration) to understand impacts of proposed new highways upon air quality, especially in urban areas. Several research groups were active in this model development, among which were: the Environmental Research and Technology (ERT) group in LexingtonLexington is a town in Middlesex County, Massachusetts, United States. The population was 31,399 at the 2010 census. This town is famous for being the site of the first shot of the American Revolution, in the Battle of Lexington on April 19, 1775.- History :...
, MassachusettsThe Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
, the ESL Inc. group in SunnyvaleSunnyvale is a city in Santa Clara County, California, United States. It is one of the major cities that make up the Silicon Valley located in the San Francisco Bay Area...
, CaliforniaCalifornia is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and the California Air Resources BoardThe California Air Resources Board, also known as CARB or ARB, is the "clean air agency" in the government of California. Established in 1967 in the Mulford-Carrell Act, combining the Bureau of Air Sanitation and the Motor Vehicle Pollution Control Board, CARB is a department within the...
group in SacramentoSacramento is the capital city of the U.S. state of California and the county seat of Sacramento County. It is located at the confluence of the Sacramento River and the American River in the northern portion of California's expansive Central Valley. With a population of 466,488 at the 2010 census,...
, CaliforniaCalifornia is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. The research of the ESL group received a boost with a contract award from the United States Environmental Protection AgencyThe U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
to validate a line source model using sulfur hexafluorideSulfur hexafluoride is an inorganic, colorless, odorless, and non-flammable greenhouse gas. has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom. It is a hypervalent molecule. Typical for a nonpolar gas, it is poorly soluble in water but soluble in...
as a tracer gas. This program was successful in validating the line source model developed by ESL inc. Some of the earliest uses of the model were in court cases involving highway air pollution, the Arlington, VirginiaThe Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
portion of Interstate 66Interstate 66 is an Interstate Highway in the eastern United States. As indicated by its even route number, it runs in an east–west direction. Its western terminus is at Middletown, Virginia, at an intersection with Interstate 81; its eastern terminus is in Washington, D.C., at an...
and the New Jersey TurnpikeThe New Jersey Turnpike is a toll road in New Jersey, maintained by the New Jersey Turnpike Authority. According to the International Bridge, Tunnel and Turnpike Association, the Turnpike is the nation's sixth-busiest toll road and is among one of the most heavily traveled highways in the United...
widening project through East Brunswick, New JerseyNew Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
.
Area source models were developed in 1971 through 1974 by the ERT and ESL groups, but addressed a smaller fraction of total air pollution emissions, so that their use and need was not as widespread as the line source model, which enjoyed hundreds of different applications as early as the 1970s. Similarly photochemical models were developed primarily in the 1960s and 1970s, but their use was more specialized and for regional needs, such as understanding smog formation in Los AngelesLos Ángeles is the capital of the province of Biobío, in the commune of the same name, in Region VIII , in the center-south of Chile. It is located between the Laja and Biobío rivers. The population is 123,445 inhabitants...
, CaliforniaCalifornia is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
.
Environmental impacts of greenhouse gas pollutants
The greenhouse effectThe greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface, energy is transferred to the surface and the lower atmosphere...
is a phenomenon whereby greenhouse gasA greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
es create a condition in the upper atmosphere causing a trapping of heatIn physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
and leading to increased surface and lower troposphericThe troposphere is the lowest portion of Earth's atmosphere. It contains approximately 80% of the atmosphere's mass and 99% of its water vapor and aerosols....
temperatures. Carbon dioxide emissions from combustion of fossil fuelFossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
s are a source of greenhouse gas emissions.
Other greenhouse gases include methaneMethane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...
, hydrofluorocarbons, perfluorocarbons, chlorofluorocarbonA chlorofluorocarbon is an organic compound that contains carbon, chlorine, and fluorine, produced as a volatile derivative of methane and ethane. A common subclass are the hydrochlorofluorocarbons , which contain hydrogen, as well. They are also commonly known by the DuPont trade name Freon...
s, nitrogen oxidesNOx is a generic term for the mono-nitrogen oxides NO and NO2 . They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures...
, and ozoneOzone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
.
This effect has been understood by scientists for about a century, and technological advancements during this period have helped increase the breadth and depth of data relating to the phenomenon. Currently, scientists are studying the role of changes in composition of greenhouse gases from natural and anthropogenic sources for the effect on climate changeClimate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
.
A number of studies have also investigated the potential for long-term rising levels of atmospheric carbon dioxide to cause increases in the acidity of ocean watersOcean acidification is the name given to the ongoing decrease in the pH and increase in acidity of the Earth's oceans, caused by the uptake of anthropogenic carbon dioxide from the atmosphere....
and the possible effects of this on marine ecosystems.
See also
- Acid rain
Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions . It can have harmful effects on plants, aquatic animals, and infrastructure. Acid rain is caused by emissions of carbon dioxide, sulfur dioxide and nitrogen...
- Air Hygiene Foundation
The Industrial Hygiene Foundation of America, originally named the Air Hygiene Foundation and also called the Industrial Health Foundation, is a business trade organization concerned with occupational health in industrial businesses...
- Air pollutant concentrations
Air 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...
- Air Quality Index
Air quality is defined as a measure of the condition of air relative to the requirements of one or more biotic species or to any human need or purpose. Air quality indices are numbers used by government agencies to characterize the quality of the air at a given location...
- Air Quality Health Index
The Air Quality Health Index or is a scale designed to help understand the impact of air quality on health. 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...
- Air stagnation
Air stagnation is a phenomenon which occurs when an air mass remains over an area for an extended period of time. Due to light winds and lack of precipitation, pollutants cannot be cleared from the air, either gaseous or particulate...
- AP 42 Compilation of Air Pollutant Emission Factors
The AP 42 Compilation of Air Pollutant Emission Factors, was first published by the U.S. Public Health Service in 1968. In 1972, it was revised and issued as the second edition by the U.S. Environmental Protection Agency . In 1985, the subsequent fourth edition was split into two volumes...
- ASEAN Agreement on Transboundary Haze Pollution
The ASEAN Agreement on Transboundary Haze Pollution is an environmental agreement signed in 2002 between all ASEAN nations to reduce haze pollution in Southeast Asia...
- Asian brown cloud
The Asian brown cloud is a layer of air pollution that covers parts of South Asia, namely the northern Indian Ocean, India, and Pakistan. Viewed from satellite photos, the cloud appears as a giant brown stain hanging in the air over much of South Asia and the Indian Ocean every year between January...
- Atmospheric chemistry
Atmospheric chemistry is a branch of atmospheric science in which the chemistry of the Earth's atmosphere and that of other planets is studied. It is a multidisciplinary field of research and draws on environmental chemistry, physics, meteorology, computer modeling, oceanography, geology and...
- Atmospheric dispersion modeling
Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that solve the mathematical equations and algorithms which simulate the pollutant dispersion...
- Beehive burner
- Best Available Control Technology
Best available control technology is a pollution control standard mandated by the United States Clean Air Act. The U.S. Environmental Protection Agency determines what air pollution control technology will be used to control a specific pollutant to a specified limit...
- Bibliography of atmospheric dispersion modeling
- Building biology
Building biology is a field of building science that investigates the indoor living environment for a variety of irritants. Practitioners consider the built environment as something with which the occupants interact, and believe its functioning can produce a restful or stressful environment...
- List of atmospheric dispersion models
- Critical load
In the study of air pollution, a critical load is defined as ”A quantitative estimate of an exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment do not occur according to present knowledge”...
- Emission standard
Emission standards are requirements that set specific limits to the amount of pollutants that can be released into the environment. Many emissions standards focus on regulating pollutants released by automobiles and other powered vehicles but they can also regulate emissions from industry, power...
- Emissions & Generation Resource Integrated Database (eGRID)
The Emissions & Generation Resource Integrated Database is a comprehensive source of data on the environmental characteristics of almost all electric power generated in the United States. eGRID is issued by the U.S...
- Environmental agreement
This is a list of international environmental agreements. Most of the following agreements are legally binding.-Alphabetical order:*Aarhus Convention Convention on Access to Information, Public Participation in Decision-making and Access to Justice in Environmental Matters, Aarhus, 1998*Alpine...
- Flue gas desulfurization
Sulfur dioxide is one of the elements forming acid rain. Tall flue-gas stacks disperse emissions by diluting the pollutants in ambient air and transporting them to other regions....
- Flue gas emissions from fossil fuel combustion
Flue-gas emissions from fossil-fuel combustion refers to the combustion product gas resulting from the much as 10 to 25 volume percent or more of the flue gas. This is closely followed in volume by water vapor created by the combustion of the hydrogen in the fuel with atmospheric oxygen...
- Global Atmosphere Watch
The Global Atmosphere Watch is a worldwide system established by the World Meteorological Organization a United Nations agency to monitor trends in the Earth's atmosphere...
- Global dimming
Global dimming is the gradual reduction in the amount of global direct irradiance at the Earth's surface that was observed for several decades after the start of systematic measurements in the 1950s. The effect varies by location, but worldwide it has been estimated to be of the order of a 4%...
- Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
- Greenhouse effect
The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface, energy is transferred to the surface and the lower atmosphere...
- Health Effects Institute
The Health Effects Institute is a independent, non-profit corporation specializing in research on the health effects of air pollution. It is headquartered in Boston, Massachusetts, USA....
(HEI)
- Indicator value
Ellenberg's indicator values are simple ordinal classes of organisms with a similar realized ecological niche along a gradient. The latest edition of Ellenberg's indicator values contain values on a 9 point scale for soil acidity, productivity/nutrients, soil humidity, continentality, soil salt...
- International Agency for Research on Cancer
The International Agency for Research on Cancer is an intergovernmental agency forming part of the World Health Organisation of the United Nations....
- Kyoto Protocol
The Kyoto Protocol is a protocol to the United Nations Framework Convention on Climate Change , aimed at fighting global warming...
- Light water reactor sustainability
- List of smogs by death toll
- Lowest Achievable Emissions Rate
Lowest Achievable Emissions Rate is used by the Environmental Protection Agency to determine if emissions from a new or modified major stationary source are acceptable under SIP guidelines....
- NASA Clean Air Study
The NASA Clean Air Study has been led by the NASA in association with the Associated Landscape Contractors of America . Its results suggest that certain common indoor plants may provide a natural way of removing toxic agents such as benzene, formaldehyde and trichloroethylene from the air, helping...
- Particulate
- Polluter pays principle
In environmental law, the polluter pays principle is enacted to make the party responsible for producing pollution responsible for paying for the damage done to the natural environment. It is regarded as a regional custom because of the strong support it has received in most Organisation for...
- Smog
Smog is a type of air pollution; the word "smog" is a portmanteau of smoke and fog. Modern smog is a type of air pollution derived from vehicular emission from internal combustion engines and industrial fumes that react in the atmosphere with sunlight to form secondary pollutants that also combine...
and HazeHaze is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. The World Meteorological Organization manual of codes includes a classification of horizontal obscuration into categories of fog, ice fog, steam fog, mist, haze, smoke, volcanic...
- Stench
- Tire fire
Tire fires, where tires are stored, dumped or processed, exist in two forms: as fast-burning events, leading to almost immediate loss of control, and as slow-burning pyrolysis which can continue for over a decade. They are noted for being difficult to extinguish. Such fires produce a lot of smoke,...
- Regulation of greenhouse gases under the Clean Air Act
The United States Environmental Protection Agency began regulating greenhouse gases under the Clean Air Act from mobile and stationary sources of air pollution for the first time on January 2, 2011...
External links
Air quality science and general information
Air quality modelling
Effects on human health
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