The major concern with air pollution relates to its effects on humans. Air pollution injures respiratory system, causes acute bronchitis, malfunctioning of human olfactory faculty.
Damage to vegetation by air pollution is of many kinds. Sulphur dioxide may damage field crops such as alfalfa and trees such as pines, especially during the growing season.
Air pollution is also a major cause of acid rain. Acid rain means the presence of excessive acids in rain water. Burning of coal, fuel wood or petroleum produces sulphur and nitrogen. These react with oxygen and are converted into their respective oxides- sulphur dioxides and nitrogen dioxides which are soluble in water. During a rain there oxides react with large quantities of water vapour of the atmosphere to form acids like sulphuric acid, sulphurous acid, nitric acid and nitrous acid. These acids when they precipitate together with rain or snow create acid rain. Acid rains increase acidity in the soil and destroy forests and crops. It corrodes buildings, monuments, statues etc.
Ozone layer depletion-The second layer of the atmosphere i.e. stratosphere which lies at the height of 20 km to 50 km from the earth’s surface, comprises the ozone layer although its density is very low. The ozone layer protects us from the ultra- violet rays and infra red rays of the sun. But when the oxides of nitrogen come in contact with ozone, their chemical reaction destroys ozone layer. Another important factor is chlorofluorocarbons which have strong power to change or damage the ozone layer. Depletion of ozone layer has serious effects on human health like sunburn, cataract, aging of the skin and skin cancer. Plant and animal planktons are damaged by UV radiation. In zoo plankton, the breeding period is shortened by changes in radiation.
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