| Epidemiologic Study Design for Investigating Respiratory Health Effects
of Complex Air Pollution Mixtures Douglas W. Dockery Environmental Epidemiology Program, Harvard School of Public Health,
665 Huntington Avenue, Bldg. 1-1414, Boston, MA 02115 Abstract
Epidemiologic studies of the respiratory health effects of air pollution are intrinsically difficult because exposure is common, expected effects at concentrations found in developed countries are weak, random misclassification of exposure is common, and the respiratory health indicators have multiple etiologies. Exposures to air pollutants also are multidimensional, generally consisting of a mixture of gases and particles. In this paper, epidemiologic study designs are described, and their potential for evaluating effects of complex pollutant mixtures are discussed. Power to detect the independent effects of individual pollutants in a complex pollutant mixture or to measure their interactions is in general very weak unless the study is specifically designed to test such hypotheses. However, with innovative and creative design, the independent and joint effects of multiple pollutants should be estimable in epidemiologic studies. -- Environ Health Perspect 101(Suppl 4) :187-191 (1993) . Key Words: Epidemiology, study design, air pollution, mixtures, respiratory health effects
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