Sources of Atmospheric Pollutants

Air pollution is one of the most problematic environmental issues facing the world today. Heavily populated cities have the biggest problems with air pollution, but pollutants can travel with the wind and affect isolated areas, and carbon dioxide and other greenhouse gases have the potential to impact the whole planet through global warming. Air pollution is divided into anthropogenic (man-made) and natural sources.

Stationary sources

• Stationary sources include coal-burning power plants, factories, incinerators, refineries and other large industrial facilities. Coal is the source of most of the world's electricity, and is the single largest contributor to rising CO2 levels. Coal combustion also produces sulfur dioxide, which mixes with water in the atmosphere to form sulfuric acid and contribute to acid rain. It emits nitrogen dioxides, which contribute to emphysema, bronchitis and heart disease, as well as creating acid rain, damaging the ozone layer and contributing to ground-level smog. Coal also puts mercury, carbon monoxide and other hazardous chemicals into the atmosphere.

  Power plants contribute to approximately 24,000 deaths per year in the United States, according to one study.

Mobile Sources

• Mobile sources, mainly automobiles but also airplanes, ships and other vehicles, are another major source of air pollution. Almost all vehicles burn some form of gasoline or other fossil fuel. The primary pollutants released by cars are carbon dioxide, carbon monoxide, nitrogen oxides, volatile organic compounds (VOCs) and particulate matter. As mentioned previously, nitrogen oxides are hazardous on their own, but they also combine with VOCs to produce ozone. Ozone helps limit harmful radiation in the upper atmosphere, but at ground level it causes respiratory illness and reduces U.S. agricultural productivity by $500 million per year.

  Particulate matter, tiny solid particles that can get stuck in the lungs, worsens asthma and causes lung cancer.

Agriculture

• Plowing can release huge amounts of dust into the atmosphere, carrying fertilizers and pesticides. Controlled burns to clear agricultural land or manage forests also contribute carbon dioxide, carbon monoxide and particulate matter to the atmosphere.

  Industrial-scale livestock farming produces significant air pollution. Cattle are a major source of methane, which is a far more powerful greenhouse gas, pound for pound, than carbon dioxide. Concentrated feeding operations that raise poultry are also a major producers of nitrogen oxides.

Landfills

• Microbial decomposition in landfills produces huge amounts of methane. Some state-of-the-art landfills capture this methane and recycle it as a useful fuel, but most often it is simply released into the atmosphere.

Military Sources

• Many modern weapons, from nuclear weapons to rockets and toxic gases, cause air pollution whether they are being used in the field or simply being tested in a remote area. Military vehicles such as tanks, jets, and navy vessels burn a great deal of fossil fuels and release carbon dioxide and other pollutants.

Aerosols

• Hair sprays, paints, varnish and other household solvents can release hazardous compounds into the air. For the most part, chlorofluorocarbons have been phased out of use in aerosols since being banned by the Montreal Protocol for their role in ozone depletion. Many still contain other toxic chemicals or greenhouse gases.

Natural sources

• Natural sources of air pollution include wind-blown dust from areas with little vegetation to hold it in place, animals and microbes (methane), wildfires (carbon monoxide, carbon dioxide, particulates), volcanoes (sulfur, ash, chlorine), and radon released from radioactive decay in the Earth's crust.