In its ideal state, the earth's atmosphere at or near sea level consists of approximately 78 percent nitrogen, 21 percent oxygen and 1 percent other gases. If it were possible to maintain this ratio, 100 percent clean air would be ours for the breathing. However, many varied causes allow other gases and particulates to mix with the air, causing it to become unclean, impure or, in a word, polluted.
Certain pollutants are visible while others are invisible. Each has the capability of distressing the eyes, ears, throat, skin and respiratory system. If certain pollutants were to be concentrated in a specific area and under the right conditions, people could die from the displacement by foreign chemicals or reduction of the oxygen content in the air. Common pollutants can and have caused 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 three separate types: natural, industrial and automotive.