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Our Glaciers: Then and Now activity kit helps you see the changes taking place in glaciers around the world. See all our activity kits and classroom activities.

Air Pollution Sources

Air pollution comes from many different sources. Natural processes that affect air quality include volcanic activity, which produce sulfur, chlorine, and ash particulates, and wildfires, which produce smoke and carbon monoxide. Cattle and other animals emit methane as part of their digestive process. Even pine trees emit volatile organic compounds (VOCs).

There are many forms of air pollution that are human-made. Industrial plants, combustion-fired power plants and vehicles with internal combustion engines generate nitrogen oxides, VOCs, carbon monoxide, carbon dioxide, sulfur dioxide and particulates. In most megacities, such as Mexico City and Los Angeles, cars are the primary source of these pollutants. Stoves and incinerators, especially ones that are coal or wood-fired, and farmers burning their crop waste produce carbon monoxide, carbon dioxide, as well as particulates. Other human-made sources include aerosol sprays and gases leaking from refrigeration systems, as well as fumes from paint, varnish, and other solvents. Additional pollutants, like ozone and acids, are made in the atmosphere when human-made gases combine chemically.

One important thing to remember about air pollution is that it doesn’t stay in one place. Winds and weather play an important part in transport of pollution locally, regionally, and even around the world, where it affects everything it comes in contact with.

Last modified February 6, 2008 by Travis Metcalfe.

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The Fall 2009 issue of The Earth Scientist, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our online store.

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