The earth's atmosphere, at or near sea level, consists of approximately 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.
Some 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 particular area under certain conditions, death could result due to the displacement, or chemical change, of the oxygen content in the air. These pollutants can also cause significant 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.