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Urban Air Quality
Urban air pollutants arise from a wide variety of sources although they are mainly a result of combustion processes. Today, the largest source of pollution in most urban areas is motor vehicles, and to a lesser extent industry. Traffic-generated pollutants include nitrogen oxides, carbon monoxide, volatile organic compounds and particulates. On warm summer days the strong sunlight leads to a buildup of ozone through the oxidation of volatile organic compounds (VOCs) such as benzene in the presence of nitrogen oxides. However, due to the special atmospheric chemistry of ground level ozone, levels are very often lower in urban areas than in the countryside.
Urban air pollution, however, is not a new problem. As far back as the 13th century, the use of coal in London was prohibited on the ground that it was prejudicial to health. During the Industrial Revolution, smog pollution in urban areas became a significant problem, due to the industrial and domestic burning of coal, releasing large quantities of smoke and sulphur dioxide. In the latter half of the 20th century, such smogs have become much rarer, with the introduction of smokeless zones in urban areas.
The Automatic Urban Monitoring Network provides the public with rapid and reliable information on urban air quality, and satisfies the statutory requirements of EC Directives on air pollution. Public information on urban air quality is available through the following sources:
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