ScrubbersThese are a diverse group of air pollution control devices that uses a high energy liquid spray to remove some particulates and/or gases from industrial exhaust streams. The gases are removed either by absorption or chemical reaction.
Secondary pollutantA pollutant formed by the combination of other (primary) pollutants in the environment. Ex: Ground level Ozone is the best example of secondary pollutant which is formed by interaction between NOx and VOC.
SmogA term coined by H. A. Des Voeux, to denote combination of smoke and natural fog which in urban areas, may have unpleasant and even disastrous consequences. Ex: London Smog. The word is also applied to other air pollution effect not necessarily connected with smoke such as ‘Los Angeles Smog’ which arises from nitrogen oxides and hydrocarbons emitted by motor vehicles and the photochemical action of sunlight.
SmokeA form of air pollution consisting primarily of particulate matter (i.e., particles released by combustion). Other components of smoke include gaseous air pollutants such as hydrocarbons, oxides of nitrogen and carbon monoxide. Sources of smoke may include fossil fuel combustion, agricultural burning and other combustion processes.
Sootfine carbon particles that have a black appearance when emitted into the air.
StratosphereLayer of the atmosphere lies between 12 and 50 km above the earth’s surface in which temperature increases with altitude.
Sulphur dioxide (SO2)A constituent of products of combustion of a wide variety of fuels, but particularly heavy fuel oil and coal. It is also released in volcanic eruptions.
Sustainable developmentDevelopment and or growth that meets the needs of the present generation without compromising the ability of future generations to meet their own needs.