Thus, pollution of one kind or another is an important factor in structuring the habitat.
Sometimes environmental pollution may result not due to human activity but by other natural factors.
On the basis of origin of pollutants they can be classified as primary or secondary pollutants. Primary Pollutants: These are emitted directly from the point source (identifiable source) e.g.
carbon monoxide (CO), oxides of nitrogen (NO), hydrocarbons, radioactive substances etc. Secondary Pollutants: These are formed by interaction of primary pollutant(s) with other primary pollutant(s) or with some natural constituents of atmosphere, e.g.
However, during all these processes the wastes and undesirable substances are continuously added to the water sources.
A general survey has revealed that nearly 70% streams and rivers in our country contain polluted water.
Degradation of air quality and natural atmospheric conditions constitute air pollution.
When, due to some natural processes or human activities, the amount of solid wastes or concentration of gases other than oxygen increase in the air which are harmful to man and his environment, then the air is said to be polluted and this process is referred to as air or atmospheric pollution.
Pollution affects not only the individual organism directly by weakening or killing it, but it also affects the population and ecosystem.
A formal definition of pollution can be said as un-favourable modification of the environment by human activities. It dates back to mid-1600s when burning of coal was recognised as the cause of air pollution which caused health problems in human.