ABSTRACT
This chapter begins by discussing the nature and sources of non-living agents of disease, briefly considering the importance of naturally occurring geogens before turning to synthetic pollutants. After discussing some of the major types of pollution, it explores ways in which public health researchers gather evidence to verify causal links between exposures and health impacts. Since the mid-twentieth century, pollution legislation, such as removing lead from gasoline, has greatly reduced environmental exposures in many affluent countries, again illustrative of the descending limb of the environmental Kuznets curve. Environmental exposures are therefore not only a critical area of ecological study, but also generate important questions of equity, invoking consideration of the ways in which societal structures influence who is subjected to the greatest risk from health hazards. The health impacts of exposure to geogens depend not only on the type, duration, and intensity of exposure, but also on the biology of the exposed individual.
