(1997), (2)“Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements” (1999), and (3) “Heavy Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements” (2000). The committee also reviewed the health benefits analysis completed for EPA’s analysis of the benefits and costs of the 1990 Clean Air Act Amendments (CAAA) (1999). All of these analyses are described in Chapter 2 of this report (see Tables 2-1 and 2-5).

Ozone and airborne particulate matter (PM) were the primary focus of the EPA analyses selected by the committee for review. Therefore, the committee spent a considerable amount of time discussing these pollutants, especially PM, and did not address issues associated with the analysis of the hazardous air pollutants (HAPs). However, many of the findings and recommendations of the committee have broad applicability and are not limited to analyses conducted for PM.

THE COMMITTEE’S EVALUATION AND FINDINGS

Despite many inherent uncertainties, the committee concludes that regulatory benefits analysis can be a useful tool for generating information valuable to policy-makers and the public. Properly conducted analyses can help identify the type, magnitude, and relative importance of health benefits, highlight the sensitivity of the benefits estimates to assumptions made in the analysis, and indicate the areas of greatest scientific uncertainty. Information from the analyses can help focus future research efforts to reduce key uncertainties. The committee emphasizes, however, that estimates of health benefits and their economic valuation are only one part of the deliberative and political processes necessary for the development of sound policy.

Estimating the health benefits of a potential reduction in ambient air pollution involves a series of steps. First, the regulatory options to be evaluated must be clearly defined with regard to scope, timing, and implementation. Then, the boundaries of the analysis, such as the time period for which benefits are evaluated, must be established. In addition, the regulatory baseline (the description of conditions without the proposed regulation) must be defined. Once the analysis has been structured, future changes in pollutant emissions and resulting changes in ambient pollutant concentrations and population exposures can be predicted. Changes in health outcomes can then be estimated by applying concentration- or exposure-response



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