Unifying susceptibility, exposure, and time:: Discussion of unifying analytic approaches and future directions

This article reviews design and analysis concepts associated with the following major issues in air pollution epidemiology: (1) time-related determinants of health effects, including duration of exposure and disentangling acute effects and total life-shortening associated with long-term exposure; and (2) the role of geographies of susceptibility and exposure including the relevance and impact of ecologic covariates in the assessment of long-term effects of ambient air pollution. The article identifies the potential contribution associated with improved information in these areas to air pollution policy development and argues that these issues should frame future approaches to assessing the total effects of ambient air pollution.