Assessing the Public Health Impact of Regional - Scale Air Quality Regulations

awma.org july 2008 em 29 The Clean Air Interstate Rule (CAIR) will further reduce regional emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx), thus reducing fine particulate matter (PM2.5) and ground-level ozone pollution in the eastern United States. The U.S. Environmental Protection Agency (EPA) estimates that CAIR will provide the largest benefits of any Clean Air Act rule issued in the past 12 years. Regulations such as CAIR, however, come at a substantial economic cost. Moreover, understanding whether we have sufficiently protected the public is of critical concern.1,2 Thus, determining whether regulatory actions actually reduce air pollution and improve public health and the environment is an important step in environmental policy implementation. This article presents an “accountability” framework for evaluating the impact of CAIR that consists of “metrics” (i.e., predictions of changes associated with the promulgation of CAIR) and “indicators” (i.e., actual levels of the same or closely related parameters observed during the implementation of CAIR). The basic challenge in this evaluation is that only the actual value of an indicator parameter will be observable, not the incremental change caused by CAIR. Thus, modeling is used to understand and supplement the observed parameter. The approach presented here addresses the regional-scale transport of pollutants and the indicators and techniques needed to discern a relatively small signal of change embedded in a highly confounded set of outcomes. The NOx State Implementation Plan (SIP) Call (implemented by the NOx Budget Trading Program [NBP]) is used as an example to discuss how some of em feature