Abstract

Air pollution is the presence of any substance in the atmosphere at a concentration high enough to produce an undesirable effect on humans, animals, vegetation, or materials, or to significantly alter the natural balance of any ecosystem. Air pollutants can be solids, liquids, or gases, and can be produced by anhropogenic activities or natural sources. Current concerns regarding air pollutants are on the effects of long term, chronic exposures to nonlethal concentrations of air pollutants, especially the pollutants defined in the Clean Air Act. These pollutants include: sulfur dioxide (SO₂); carbon monoxide (CO); nitrogen dioxide, (NO₂); ozone (O₃); suspended particluates; volatile organic compounds (VOCs); and lead, (Pb). The impacts of indoor air quality on health, the effects of air pollution on global and regional climate, and the effects of air pollutants on global and regional atmospheric cycles (eg, stratospheric ozone depletion and acid deposition) have also emerged as concerns.