POLLUTION is defined as an unwanted change in the physical, chemical and biological characteristics of air, land and water.
Pollution are of mainly three types:
SOIL POLLUTION: is caused by urban waste, industrial waste, biological agents, radioactive pollution.
AIR POLUTION: is caused by smoke from vehicles, combustion of coal and petroleum, thermal power plants.
WATER POLLUTION: is caused by waste effluents, industrial effluents, surface run-off, thermal pollution, radioactive wastes, marine pollution.
There may be Noise pollution also.
All kind of pollution have an adverse effect on human beings, plants and animals.