The Influence of Responses in Susceptible Populations in Establishing Standards for Ambient Air Pollutants

This paper reviews the ways in which pollutant-related responses among especially susceptible population groups affect the establishment of primary (health related) National Ambient Air Quality Standards (NAAQSs). It includes the Environmental Protection Agency's (EPA's) interpretation of its statutory authority for addressing such considerations in standard setting; definitions of terms such as adverse effects, adequate margin of safety, and sensitive population groups; and a summary of the actions taken in setting standards for the six criteria pollutants, carbon monoxide (CO), nitrogen dioxide (NO₂), paniculate matter (PM), sulfur dioxide (SO₂), ozone (O₃), and lead (Pb). In each case, the NAAQSs have been selected to provide protection against either known or hypothetical responses among one or more susceptible subpopulations, such as angina in cardiovascular patients exposed to CO, bronchoconstriction in exercising asthmatics exposed to SO₂, and neurobehavioral responses in preschool children exposed to Pb.