primary analyses, it should analytically determine which uncertainty sources have the greatest influence on the mean and spread of the probability distributions. The uncertainty sources that have the greatest impact on the spread of the distribution should receive high priority for additional research.

  • In presenting the probability distribution for each health benefit estimated in the primary analysis, EPA should more clearly identify the sources of uncertainty that are not evaluated in the primary analysis.

  • Although the results of the benefits analyses may appear to be less certain, EPA should describe the uncertainty as completely and realistically as possible, recognizing that regulatory action might be necessary in the presence of substantial uncertainty.

  • EPA should consider providing preliminary analyses that estimate in current populations the health benefits resulting from hypothetical changes in current levels of emissions. Such preliminary analyses would help EPA develop an idea of the lower bound on the range of uncertainty. These analyses also would have fewer uncertainties than estimates based on projected future population exposures and health outcomes.

  • In all stages of the benefits analysis, EPA should justify and clearly describe the assumptions and methods used to estimate health benefits.

  • Each benefits analysis should be accompanied by a brief summary, such as 20 to 30 pages in length, that provides all critical elements of the analysis and the results, so that the reader can approximately estimate the benefits on a national level from the information provided.

  • To enhance the quality of future regulatory benefits analyses, a standing, independent, technical review panel should advise EPA in the initial stages of its benefits analysis. This panel should have expertise in regulatory options analysis, emissions and exposure assessment, toxicology, epidemiology, risk analysis, biostatistics, and economics and should be appointed with strict attention to avoiding conflict of interest, balancing biases, and ensuring broad representation. The panel should also be supported by permanent technical staff to ensure consistency of reviews over time. EPA should follow the panel’s guidance on the need for peer review.

  • In reviewing EPA's health benefits analyses, the committee identified several research needs. Some are relevant to improving the scientific basis for estimating the health benefits of further reductions of PM and other air pollutants. These research recommendations are mentioned in the body of the report. Others have to do with the development of improved methods for health benefits analyses in general. The research recommen-



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