Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms.[1]Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants. Pollution is often classed as point source or nonpoint source pollution. The Blacksmith Institute issues an annual list of the world’s worst polluted places. In the 2007 issues the ten top nominees are located in Azerbaijan, China, India, Peru, Russia, Ukraine andZambia.[2]

The major forms of pollution are listed below along with the particular pollutants relevant to each of them:
* Air pollution:- the release of chemicals and particulates into the atmosphere. Common gaseous pollutants include carbon monoxide, sulfur dioxide, chlorofluorocarbons (CFCs) and nitrogen oxides produced by industry and motor vehicles. Photochemical ozone and smog are created as nitrogen oxides and hydrocarbons react to sunlight. Particulate matter, or fine dust is characterized by their micrometre size PM10 to PM2.5.
* Light pollution:- includes light trespass, over-illumination and astronomical interference.
* Littering:- the criminal throwing of inappropriate man-made objects, unremoved, onto public and private properties.
* Noise pollution:- which encompasses roadway noise, aircraft noise, industrial noise as well as high-intensity sonar.
* Soil contamination occurs when chemicals are released by spill or underground leakage. Among the most significant soil contaminants are hydrocarbons, heavy metals, MTBE,[10] herbicides,pesticides and chlorinated hydrocarbons.
* Radioactive contamination, resulting from 20th century activities in atomic physics, such as nuclear power generation and nuclear weapons research, manufacture and deployment. (Seealpha.