The term pollution refers to any change in the natural quality of the environment brought about by chemical,physical or biological factors. Thus, environmental pollution refers to any unfavourable alteration of our surroundings,wholly or largely as a byproduct of man’s actions.


Pollution can be classified as follows: On the basis of the part of the environment where it takes place- atmosphere, hydrosphere and lithosphere , it is known as air pollution ,water pollution and soil pollution, respectively.


Air pollution is the excessive concentration of foreign matter in the air which adversely affects the well beings, animals, plants and their environment. Air pollution takes place through the pollutants of gas, solid and liquid particles of both organic and inorganic chemicals .Gases such as sulphur dioxide, carbon monoxide, hydrogen sulphide , pollens from plants etc. are continuously added to the air thereby, lowering its quality. Thus, the natural composition of the air is disturbed by natural or by man made sources.


Water pollution can be defined as alteration in physical, chemical or biological characteristics of water,making it unsuitable for designated use in its natural state. WHO has defined water pollution as any foreign material either from natural or other sources that may contaminate the water supply and make it harmful to life. Pollution of water leads to reduction of normal oxygen level of water, causes aesthetically unpalatable effects and spread of epidemic diseases.Water pollution impacts the entire food chain and affects human health as toxins from contaminated fishes,prawns etc, get deposited in human tissues. This leads to cancer,birth defects or long term health problems.


Soil is the upper layer of earth’s crust which is formed by weathering of rocks.Organic matter in the soil makes it suitable for living organisms. Soil pollution is defined as the change in physical, chemical and biological conditions of the soil throghs man intervention resulting in degradation in quality and productivity of the soil. The pollutants enter the food chain at the plant level and get magnified as we move up the food chain. Also soil pollution differs air and water pollution as the pollutants remain in soil for longer period.


Noise pollution is defined as an unwanted sound that is an irritant and a source of stress. Sound is the means of communication and entertainment. A low sound is pleasant but a loud sound is unpleasant and is often referred to as a noise. Noise is a physical form of pollution which is not directly harmful to the life supporting systems namely air, water and soil. Its effects are more directly felt by the receiver .Most of the noise originates from modern industrialised urban life. The main sources of noise pollution are industrial sector ,transport sector ,household sector defence sector ,loud speakers etc.