Air pollution episodes occur when there is an excessive concentration of pollutants in the air; atmospheric stagnation retains the pollutants and permits their build-up. Increased industrial and technological development, urbanization and high-density population, and atmospheric stagnation combine to produce serious air pollution episodes.
Atmospheric stagnation may occur with temperature inversions (ie, a mass of warm air accumulating over an area trapping cooler air beneath it), low wind speed, or high pressure air masses over an area. Local geographic features may also contribute to air stagnation. This situation results in confining pollutants that are emitted into the air, either from automobile exhausts, combustion of fossil fuels in commercial, industrial, or residential buildings, or related sources.
Increased deaths and disability are associated with periods of especially high pollution. Those who suffer most are the very young, the elderly, and individuals with respiratory or cardiorespiratory difficulties.
Two major forms of air pollution occur,
Physician's Guide to Air Pollution Episodes. JAMA. 1972;221(2):190–191. doi:10.1001/jama.1972.03200150054017