According to the Dictionary meaning the environment is the complete range of external conditions under which an organism lives- including physical, chemical and biological factors. Such as temperature, light, and the availability of food and water. Pollution which literally means to make or render unclean is an undesirable change in the physical, chemical and biological characteristics of the land, air and water that harmfully affect human life or that of desirable species.
Pollutants occur naturally as well as due to human activity. Sulphur from volcanic eruptions, radioactive materials in nature, hydrocarbons in the atmosphere are the natural pollutants but their effect is not as drastic as that of man made pollutants. With increasing populations, rapid and unplanned industrialization, urbanization and deforestation, pollution of the environment has become a major problem. There are mainly five types of environmental pollution:
(i) Air Pollution:
According to WHO air pollution is defined as the presence of materials in the air that are harmful to man and his environment. There are various sources of air pollution such as (a) Industrial pollutants released into the air from the industrial units and powerhouses namely sulphur dioxide, carbon dioxide, carbon monoxide, nitrous oxide, b) domestic pollutants eg- fossil fuels burnt by humans, (c) Automobile exhaust or vehicular emissions. These air pollutants are causing adverse effects on biodiversity and human health. For example-carbon monoxide has affinity with hemoglobin. It enters the blood stream and replaces oxygen from the blood.
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Suspended Particulate Matter (SPM) like five dust particles, Asbestos dusts emitted from industrial units causing lungs damage. Another pollutant lead causes nervous disorders and brain damage.
(ii) Water Pollution:
Water is another basic amenity of life. Over the years it has been extensively being polluted due to domestic sewage, industrial waste, and chemical inputs of agriculture.
The health hazard caused by water pollutions are (i) spread of epidemics like cholera, jaundice, dysentry, typhoid, gastroenteritis etc. (ii) Mercury, lead zinc like metals dumped by industrial units in the water resources are the causes of nervous disorders (iii) release of dyes by the industrial units into the water resources results in the use of these by the human and domestic animals causing havoc with the biological process.
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(iii) Land Pollution:
Increase in population in the urban areas due to urbanization, industrialisation has resulted in the disposal of wastes in vast land areas. Land is also being polluted by solids and liquid waste by the paper and pulp mills, oil refineries, power plants etc. Use of fertilizers, pesticides herbicides and insecticides for enhancing agriculture productivity results in land pollution.
(iv) Radiation Pollution:
People in all walks of life have been injured. Irradiation produces highly reactive chemical substances in cells and chromosomes. It can also alter the genetic material. A beam of radiation acts like bullet, when it hits a gene. It shoots a hole in it and causes mutation in genes. Thus, it is the source of various genetic disorders.
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(v) Noise Pollution:
Noise pollution is another serious threat to the environment Noise exceeding 90 dB produces ill effect on the health. Higher levels often cause permanent injury to hearing.