An air pollution control strategy for a region is a specification of the allowable levels of pollutant emissions from sources. To fonnulate such a strategy it is necessary to be able to estimate the atmospheric fate of the emissions, and thus the ambient concentrations Each pollutant gives different impact. Therefore, we need different strategy too to control the pollution. In order to do that, we have to know the types of air pollutant.
Oxides of Nitrogen
Nitric oxide (NO) and nitrogen dioxide (N02) are the two most important nitrogen oxide air pollutants. They are frequently lumped together under the designation NOx, although analytical techniques can distinguish clearly between them. Of the two, N02 is the more toxic and irritating compound. Mobile combustion and fossil-fuel power generation are the two largest anthropogenic sources of NOx. In addition, industrial processes and agricultural operations produce minor quantities.
Sulfur Oxides
Sulfur dioxide (S02) is formed from the oxidation of sulfur contained in fuel as well as from certain industrial processes that utilize sulfur-containing compounds. Anthropogenic emissions of S02 result almost exclusively from stationary point sources. Stationary fuel combustion (primarily utility and industrial) and industrial processes (primarily smelting) are the main S02 sources. Stationary fuel combustion includes all boilers, heaters, and furnaces found in utilities, industry, and commercial! institutional and residential establishments. Coal combustion has traditionally been the largest stationary fuel combustion source, although industrial and residential coal use has declined. Increased coal use by electric utilities, however, has offset this decrease.
Organic Compounds
Organic air pollutants are sometimes divided according to volatile organic compounds (VOCs) and particulate organic compounds (POCs), although there are some species that will actually be distributed between the gaseous and particulate phases. The emission of unburned or partially burned fuel from combustion processes and escape of organic vapors from industrial operations are the major anthropogenic sources of organic air pollutants. A major source of airborne organic compounds is the emissions from motor vehicles.
Particulate Matter
Particulate matter refers to everything emitted in the form of a condensed (liquid or solid) phase. Major industrial process sources of particulate matter include the metals, mineral products, petroleum, and chemicals industries. Iron and steel and primary smelting operations are the most significant emission sources in the metals industry. The iron and steel industry involves coke, iron, and steel production, each of which is a source of particulate emissions. The primary metals industry includes the smelting of copper, lead, and zinc, along with aluminum production. Sulfur in unprocessed ores is converted to S02 during smelting, with a relatively small portion emitted as particulate sulfate and sulfuric acid. Emissions from the mineral products industry result from the production of portland cement, asphalt, crushed rock, lime, glass, gypsum, brick, fiberglass, phosphate rock, and potash. The particles emitted from crushing, screening, conveying, grinding, and loading operations tend to be larger than 15 p.m.
Reference:
Richard C. Flagan, Fundamentals of Air Pollution Engineering, Prentice Hall
