Air pollution

Air pollution is the human introduction into the atmosphere of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damage the environment.[1] Air pollution causes deaths[2] and respiratory disease.[3] Air pollution is often identified with major stationary sources, but the greatest source of emissions is mobile sources, mainly automobiles.[4] Gases such as carbon dioxide, which contribute to global warming, have recently gained recognition as pollutants by climate scientists, while they also recognize that carbon dioxide is essential for plant life through photosynthesis.
The atmosphere is a complex, dynamic natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems.
Contents[hide]
1 Pollutants
2 Sources
2.1 Emission factors
3 Indoor air quality (IAQ)
4 Health effects
4.1 Effects on cystic fibrosis
4.2 Effects on COPD
4.3 London Fog of 1952
4.4 Effects on children
5 Reduction efforts
5.1 Control devices
6 Legal regulations
6.1 Canada
6.2 European Union
6.3 United Kingdom
6.4 United States
7 Statistics
7.1 Most Polluted Cities
7.2 Carbon dioxide emissions
8 Atmospheric dispersion
9 Environmental impacts
10 See also
11 References
12 External links
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[edit] Pollutants

Before flue gas desulfurization was installed, the emissions from this power plant in New Mexico contained excessive amounts of sulfur dioxide.
There are many substances in the air which may impair the health of plants and animals (including humans), or reduce visibility. These arise both from natural processes and human activity. Substances not naturally found in the air or at greater concentrations or in different locations from usual are referred to as pollutants.
Pollutants can be classified as either primary or secondary. Primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption or the carbon monoxide gas from a motor vehicle exhaust.
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.
Note that 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 oxides (SOx) especially sulfur dioxide are emitted from burning of coal and oil.
Nitrogen oxides (NOx) especially nitrogen dioxide are emitted from high temperature combustion. Can be seen as the brown haze dome above or plume downwind of cities.
Carbon monoxide is colourless, odourless, 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 (CO2), a greenhouse gas emitted from combustion.
Volatile organic compounds (VOC), such as hydrocarbon fuel vapors and solvents.
Particulate matter (PM), measured as smoke and dust. PM10 is the fraction of suspended particles 10 micrometers in diameter and smaller that will enter the nasal cavity. PM2.5 has a maximum particle size of 2.5 µm and will enter the bronchies and lungs.
Toxic metals, such as lead, cadmium and copper.
Chlorofluorocarbons (CFCs), harmful to the ozone layer emitted from products currently banned from use.
Ammonia (NH3) emitted from agricultural processes.
Odors, such as from garbage, sewage, and industrial processes
Radioactive pollutants produced by nuclear explosions and war explosives, and natural processes such as radon.
Secondary pollutants include:
Particulate matter formed from gaseous primary pollutants and compounds in photochemical smog, such as nitrogen dioxide.
Ground level ozone (O3) formed from NOx and VOCs.
Peroxyacetyl nitrate (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 and in Europe under the Air Framework Directive.
A variety of persistent organic pollutants, which can attach to particulate matter.

[edit] Sources

Dust storm approaching Stratford, Texas

Using a controlled burn on a field in South Georgia in preparation for spring planting.

Puxi area of Shanghai at sunset. The sun has not actually dropped below the horizon yet, rather it has reached the smog line.
Sources of air pollution refer to the various locations, activities or factors which are responsible for the releasing of pollutants in the atmosphere. These sources can be classified into two major categories which are:
Anthropogenic sources (human activity) mostly related to burning different kinds of fuel
"Stationary Sources" as smoke stacks of power plants, manufacturing facilities, municipal waste incinerators.
"Mobile Sources" as motor vehicles, aircraft etc.
Marine vessels, such as container ships or cruise ships, and related port air pollution.
Burning wood, fireplaces, stoves, furnaces and incinerators .
Oil refining, and industrial activity in general.
Chemicals, dust and controlled burn practices in agriculture and forestry management, (see Dust Bowl).
Fumes from paint, hair spray, varnish, aerosol sprays and other solvents.
Waste deposition in landfills, which generate methane.
Military, such as nuclear weapons, toxic gases, germ warfare and rocketry.
Natural sources
Dust from natural sources, usually large areas of land with little or no vegetation.
Methane, emitted by the digestion of food by animals, for example cattle.
Radon gas from radioactive decay within the Earth's crust.
Smoke and carbon monoxide from wildfires.
Volcanic activity, which produce sulfur, chlorine, and ash particulates.

[edit] Emission factors
Main article: AP 42 Compilation of Air Pollutant Emission Factors
Air pollutant emission factors are representative values that attempt to relate the quantity of a pollutant released to the ambient air with an activity associated with the release of that pollutant. These factors are usually expressed as the weight of pollutant divided by a unit weight, volume, distance, or duration of the activity emitting the pollutant (e.g., kilograms of particulate emitted per 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.
The United States Environmental Protection Agency has published a compilation of air pollutant emission factors for a multitude of industrial sources.[5] The United Kingdom, Australia, Canada and other countries have published similar compilations, as has the European Environment Agency.[6][7] [8][9] [10]

[edit] Indoor air quality (IAQ)
Main article: Indoor air quality
A lack of ventilation indoors concentrates air pollution where people often spend the majority of their time. Radon (Rn) gas, a carcinogen, is exuded from the Earth in certain locations and trapped inside houses. Building materials including carpeting and plywood emit formaldehyde (H2CO) gas. Paint and solvents give off volatile organic compounds (VOCs) as they dry. Lead paint can degenerate into dust and be inhaled. Intentional air pollution is introduced with the use of air fresheners, incense, and other scented items. Controlled wood fires in stoves and fireplaces can add significant amounts of smoke particulates into the air, inside and out. Indoor pollution fatalities may be caused by using pesticides 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 charcoal indoors. Chronic carbon monoxide poisoning can result even from poorly adjusted pilot lights. Traps are built into all domestic plumbing to keep sewer gas, hydrogen sulfide, out of interiors. Clothing emits tetrachloroethylene, or other dry cleaning fluids, for days after dry cleaning.
Though its use has now been banned in many countries, the extensive use of asbestos in industrial and domestic environments in the past has left a potentially very dangerous material in many localities. Asbestosis is a chronic inflammatory medical condition affecting the tissue of the lungs. It occurs after long-term, heavy exposure to asbestos from asbestos-containing materials in structures. Sufferers have severe dyspnea (shortness of breath) and are at an increased risk regarding several different types of lung cancer. As clear explanations are not always stressed in non-technical literature, care should be taken to distinguish between several forms of relevant diseases. According to the World Health Organisation (WHO), these may defined as; asbestosis, lung cancer, and mesothelioma (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. Pets produce dander, people produce dust from minute skin flakes and decomposed hair, dust mites in bedding, carpeting and furniture produce enzymes and micrometre-sized fecal droppings, inhabitants emit methane, mold forms in walls and generates mycotoxins and spores, air conditioning systems can incubate Legionnaires' disease and mold, and houseplants, soil and surrounding gardens can produce pollen, dust, and mold. Indoors, the lack of air circulation allows these airborne pollutants to accumulate more than they would otherwise occur in nature.

[edit] 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.[3] A study by the University of Birmingham has shown a strong correlation between pneumonia related deaths and air pollution from motor vehicles. [11] Worldwide more deaths per year are linked to air pollution than to automobile accidents.[citation needed] Published in 2005 suggests that 310,000 Europeans die from air pollution annually.[citation needed] Direct causes of air pollution related deaths include aggravated asthma, bronchitis, emphysema, lung and heart diseases, and respiratory allergies.[citation needed] The US EPA estimates that a proposed set of changes in diesel engine technology (Tier 2) could result in 12,000 fewer premature mortalities, 15,000 fewer heart attacks, 6,000 fewer emergency room visits by children with asthma, and 8,900 fewer respiratory-related hospital admissions each year in the United States.[citation needed]
The worst short term civilian pollution crisis in India was the 1984 Bhopal Disaster.[12] Leaked industrial vapors from the Union Carbide factory, belonging to Union Carbide, Inc., U.S.A., killed more than 2,000 people outright and injured anywhere from 150,000 to 600,000 others, some 6,000 of whom would later die from their injuries.[citation needed] The United Kingdom suffered its worst air pollution event when the December 4 Great Smog of 1952 formed over London. In six days more than 4,000 died, and 8,000 more died within the following months.[citation needed] An accidental leak of anthrax spores from a biological warfare laboratory in the former USSR in 1979 near Sverdlovsk is believed to have been the cause of hundreds of civilian deaths.[citation needed] The worst single incident of air pollution to occur in the United States of America occurred in Donora, Pennsylvania in late October, 1948, when 20 people died and over 7,000 were injured.[13]
The health effects caused by air pollutants may range from subtle biochemical and physiological changes to 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.[citation needed]

[edit] Effects on cystic fibrosis
A study from 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. [14] Patients were examined before the study for amounts of specific pollutants like P. aeruginosa or B. cepacia as well as their socioeconomic standing. Participants involved in the study were located in the United States in close proximity to an Environmental Protection Agency .During the time of the study 117 deaths were associated with air pollution. A trend was noticed that patients living closer or in large metropolitan areas to be close to medical help also had higher level of pollutants found in their system because of more emissions in larger cities. With cystic fibrosis patients already being born with decreased lung function everyday pollutants such as smoke emissions from automobiles, tobacco smoke and improper use of indoor heating devices could add to the dissemination of lung function.[15]

[edit] Effects on COPD
Chronic obstructive pulmonary disease (COPD) include diseases such as chronic bronchitis, emphysema, and some forms of asthma.[16] Two researchers Holland and Reid conducted research on 293 male postal workers in London during the time of the 1952 London Fog incident and 477 male postal workers in the rural setting. The amount of the pollutant FEV1 was significantly lower in urban employees however lung function was decreased due to city pollutions such as car fumes and increased amount of cigarette exposure.[17] It is believed that much like cystic fibrosis, by living in a more urban environment serious health hazards become more apparent. Studies have shown that in urban areas patients suffer mucus hypersecretion, lower levels of lung function, and more self diagnosis of chronic bronchitis and emphysema.[18]

[edit] London Fog of 1952
In the matter of four days a combination of dense fog and sooty black coal smoke came over the London area. [19] The fog was so dense residents of London could not see in front of them. The extreme reduction in visibility was accompanied by an increase in criminal activity as well as transportation delays and a virtual shut down of the city. During the 4 day period of the fog 12,000 are believed to have been killed.[20]

[edit] Effects on children
Cities around the world with high exposure to air pollutants has 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 is being taken in countries such as New Delhi where buses now use compressed natural gas to help eliminate the “pea-soup” fog.[21] Research by the World Health Organization 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 Egypt, Sudan, Mongolia, and Indonesia. The Clean Air Act was passed in 1970, however in 2002 at least 146 million Americans were living in areas that did not meet at least one of the “criteria pollutants” laid out in the 1997 National Ambient Air Quality Standards. [22] Those pollutants included: 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.