Air Pollution

Abstract

It is somewhat artificial to consider air, water, and soil pollution separately because their effects are interchangeable. Chemicals emitted into the air eventually combine with rain or snow and settle down to become water and land pollutants. On the other hand, volatile chemicals from soil or those that enter lakes and rivers evaporate to become air pollutants. Pesticides sprayed on land are carried by the wind to become transient air pollutants that eventually settle somewhere on land or water. For discussion purposes, however, some systematic division appears to be advisable. Although the problems of air pollution have been recognized for many decades, they were once considered to be only of local significance, restricted to industrial urban areas. With the current recognition of the destruction of stratospheric ozone, the greenhouse effect, worldwide forest destruction, and the acidification of lakes and coastal waters, air pollution assumes global significance. The sources of urban air pollution are . power generation . transportation . industry, manufacturing, and processing . residential heating . waste incineration Except for waste incineration, all of these pollution sources depend on fossil fuel and, to a lesser degree, on fuel from renewable resources such as plant material. Therefore, all of them produce essentially the same pollutants, although the quantity of each substance may vary from source to source. The principal incineration-generated pollutants are carbon monoxide (CO), sulfur dioxide (SO2), a mixture of nitrogen oxides (NOx), a mixture of hydrocarbons, referred to as volatile organic compounds (VOCs), suspended particulate matter (SPM) of varying sizes, and metals, mostly bound to particles. Waste incineration, in addition, produces some chlorinated dioxins and furans that are formed on combustion of chlorine-containing organic substances Most of these air pollutants originate from geophysical, biological, and atmospheric sources. Their contribution to total air pollution is globally significant. This fact should not lead us into complacency about anthropogenic air pollution. In nature, a steady state has been established between emission and disposition of biogenic pollutants. Life on earth developed in harmony with these external influences.