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AIR POLLUTION
Introduction
The earth's atmosphere, at or near sea level, consists approximately of 78%
nitrogen, 21% oxygen and 1% other gases. If it were possible to remain in this
state, 100% clean air would result. However, many varied causes allow other
gases and particulates to mix with the clean air, causing the air to become
unclean or polluted.
Certain of these pollutants are visible while others are invisible, with each having
the capability of causing distress to the eyes, ears, throat, skin and respiratory
system. Should these pollutants be concentrated in a specific area and under the
right conditions, death could result due to the displacement or chemical change of
the oxygen content in the air. These pollutants can cause much damage to the
environment and to the many man made objects that are exposed to the
elements.
To better understand the causes of air pollution, the pollutants can be categorized
into 3 separate types, natural, industrial and automotive.
Natural Pollutants
Natural pollution has been present on earth before man appeared, and is still a
factor to be considered when discussing air pollution, although it causes only a
small percentage of the present overall pollution problem existing in our country.
It is the direct result of decaying organic matter, wind born smoke and
particulates from such natural events as plains and forest fires (ignited by heat or
lightning), volcanic ash, sand and dust which can spread over a large area of the
countryside.
Such a phenomenon of natural pollution has been recent volcanic eruptions, with
the resulting plume of smoke, steam and volcanic ash blotting out the sun's rays
as it spreads and rises higher into the atmosphere, where the upper air currents
catch and carry the smoke and ash, while condensing the steam back into water
vapor. As the water vapor, smoke and ash traveled on their journey, the smoke
dissipates into the atmosphere while the ash and moisture settle back to earth in
a trail hundred of miles long. In many cases, lives are lost and millions of dollars
of property damage result, and ironically, man can only stand by and watch it
happen.
Industrial Pollutants
Industrial pollution is caused primarily by industrial processes, the burning of
coal, oil and natural gas, which in turn produces smoke and fumes. Because the
burning fuels contain much sulfur, the principal ingredients of smoke and fumes
are sulfur dioxide (SO
2
) and particulate matter. This type of pollutant occurs most
severely during still, damp and cool weather, such as at night. Even in its less
severe form, this pollutant is not confined to just cities. Because of air
movements, the pollutants move for miles over the surrounding countryside,
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18.11.2005 http://www.chiltondiy.com/content/8687/8687_4_1.html