Pollution is an undesirable change in the physical, chemical or biological characteristics of air, water, land or soil that may have detrimental effects on the living organisms. Substances that bring about such changes are called pollutants. The air has become highly polluted over the last decade due to automobile exhausts and chemicals and toxic gases from industries and natural particulate matter.
The concentration of the pollutants and the duration of exposure have detrimental effects on all living organisms. When exposed to polluted air, plants exhibit leaf-blade damage, cellular collapse, premature aging, reduced growth and crop yields (or the plants may even die), while animals exhibit eye and nasal irritation, headache, shortness of breath and respiratory diseases.
In 1986, our government passed the Environment Protection Act to take action to control environmental pollution. This Act made several industries and thermal power plants adopt various methods to filter particulate and gaseous matter that were released into the atmosphere. The widely used method to filter particulate matter is electrostatic precipitator, which removes over 99 per cent of particulate matter present in industrial exhaust. Another method is the use of scrubbers, but is incapable of removing very tiny particulate matter. According to the Central Pollution Control Board or CPCB, particulate matter measuring 2.5 micrometers or less causes respiratory diseases.
The emission of poisonous gases from automobiles is minimised by using catalytic converters, compressed natural gas or CNG, low-sulphur petrol and diesel and unleaded petrol. The catalytic converters contain catalysts, which change poisonous exhaust gases such as un-burnt hydrocarbons into carbon dioxide and water, carbon monoxide and nitric oxide into carbon dioxide and nitrogen gas, respectively.
Noise is an undesirable, high level of sound. Exposure to a sound level of more than 150 decibels or prolonged exposure to lower sound levels may damage the eardrum, thereby permanently impairing hearing ability. Noise also causes sleeplessness, stress, increased heartbeat and an altered breathing pattern. To minimise noise pollution, industries need to use sound-absorbent materials and workers exposed to loud sound levels should use ear puffs.