POLLUTION

Pollution is the introduction of contaminants into an environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances, or energy, such as noise, heat, or light energy. Pollutants, the elements of pollution, can be foreign substances or energies, or naturally occurring; when naturally occurring, they are considered contaminants when they exceed natural levels. Pollution is often classed as point source or non point source pollution. The Blacksmith Institute issues annually a list of the world's worst polluted places.

Air pollution, the release of chemicals and particulates into the atmosphere. Common gaseous air 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 micrometer size. Air pollution comes from both natural and manmade sources.

Water pollution, by the release of waste products and contaminants into surface runoff into river drainage systems, leaching into groundwater, liquid spills, wastewater discharges, eutrophication and littering. Soil contamination occurs when chemicals are released by spill or underground leakage. Radioactive contamination, resulting from Twentieth century activities in atomic physics, such as nuclear power generation and nuclear weapons research, manufacture and deployment.

Noise, which encompasses roadway noise, aircraft noise, industrial noise as well as high-intensity sonar. Light pollution, includes light trespass, over-illumination and astronomical interference. Visual pollution, which can refer to the presence of overhead power lines, motorway billboards, scarred landforms, open storage of trash or municipal solid waste. Thermal pollution, is a temperature change in natural water bodies caused by human influence, such as use of water as coolant in a power plant.

Pollution control is a term used in environmental management. It means the control of emissions and effluents into air, water or soil. Without pollution control, the waste products from consumption, heating, agriculture, mining, manufacturing, transportation and other human activities, whether they accumulate or disperse, will degrade the environment. In the hierarchy of controls, pollution prevention and waste minimization are more desirable than pollution control.