Air pollution

From Wikinfo

[[es:contaminaci�n atmosf�rica]]

Air pollution is a broad term applied to all chemical and biological agents that modify the natural characteristics of the atmosphere.

Some definitions also consider physical perturbations such as noise pollution, heat, radiation or light pollution as air pollution. Some definitions include the term harmful as a requisite to consider a change to the atmosphere as pollution.

Contents 1 Causes 2 Contaminants 3 See also 4 Further Reading 5 Sources 5.1 References

Causes

The sources of air pollution are divided in two groups: anthropogenic (generated by human activity) and natural.

Natural sources include:

• Volcanic activity.
• Dust from natural sources, usually large areas of land with little or no vegetation.
• Gases, such as methane, emitted by the digestion of animals, usually cattle.
• Smoke from wildfires.

Anthropogenic sources are mostly related to burning different kinds of fuel. They include:

• Dust and chemicals from farming, especially of erodible land, see Dust Bowl. Air pollution from farming is effectively unregulated in the United States due to a grant of power to the states of regulatory power. Typically, as in Colorado, this power is passed on to a state department of agriculture which is controlled by agricultural interests. Recently in California due to extensive health problems some regulations have been put in place [1].
• Industrial activity in general.
• Vehicles with internal-combustion engines.
• Stoves and incinerators, specially coal ones.
• Paint fumes, or other toxical vapors.
• Aerosols.

Contaminants

Contaminants of air can be divided in particles and gases.

Particles are classified by their sizes. A usual division is in PM10 and PM2.5. PM10 are particles whose size is less than 10 micrometres; they are dangerous to humans because they can be breathed and reach the lungs. PM2.5 are particles whose size is less than 2.5 micrometres, and they are even more dangerous because they can pass the alveoli and reach the blood.

Important pollutant gases include:

• Carbon monoxide.
• Nitrogen oxides.
• Hydrocarbons.
• Ozone in the lower part of the atmosphere (in the upper part, it helps to reduce the amount of ultraviolet radiation from the sun that reaches earth).
• Sulfur dioxide, which causes acid rain.

The worst single incident of air pollution to occur in the United States of America occurred in Donora, Pennsylvania in late October, 1948

See also

• emissions trading
• Greenhouse effect
• Kyoto Protocol

Further Reading

• Davis, Devra, When Smoke Ran Like Water: Tales of Environmental Deception and the Battle Against Pollution, Basic Books, 2002, hardcover, 316 pages, ISBN 0-465-01521-2

Sources

• SantiagoLimpio.CL - Website of the environmental agency of Chile
• Local air pollution - On a site by the Australian Academy of science

References

• Adapted from the Wikipedia article, "Air_pollution" http://en.wikipedia.org/wiki/Air_pollution, used under the GNU Free Documentation License