Atmospheric formation and fates of toxic ambient air pollutants

Concentrations of de novo toxicants in ambient air are typically in the ppb range, compared to ppm for occupational exposures. Despite this, some species such as ozone, alone or in combination with other pollutants, have significant health impacts, especially on populations such as children, the elderly, and asthmatics. Reaction products in the atmosphere include gases such as ozone and nitric acid, as well as polar organic species such as aldehydes, acids, hydroperoxides, and peroxides. A brief discussion of indoor vs outdoor levels of several acids/toxicants is included. Emphasis is on homogeneous, gas-phase processes with some examples of gas/solid heterogeneous processes. A brief discussion is included on the role of chlorofluorocarbons in the catalytic destruction of stratospheric ozone in the context of the resulting expected increase in ultraviolet radiation at the earth's surface.