the large amounts of new information being developed in this research program.

Third, and perhaps most important, sustained and substantially enhanced management of this program by EPA, accompanied by a continuing mechanism for independent review and oversight of the program, will be the only way to ensure that this investment is being soundly made. EPA has taken steps toward better management, but recent frequent transitions in management personnel of that effort and a substantial need for new management systems and administrative mechanisms for supporting research—especially on the topic of assessment of hazardous PM components—suggest that EPA will need to enhance its efforts. Also, it will be important to develop some form of continuing independent oversight to provide continued monitoring and guidance for EPA’s and others’ efforts.

Much has been learned from the research investment since 1998, and evidence gained by the investment is already being used in decisionmaking, which will continue even in the face of uncertainty. However, much is still to be learned. A failure to invest in developing greater understanding of the effects of PM and air pollution, in general, on health would result in not taking full advantage of the substantial research investment to date and in limiting the nation’s ability to make evidence-based health policy and air quality regulatory choices in the future. Alternatively, continued enhancement of the air pollution and health research effort will undoubtedly yield substantial benefits for years to come. It is clearly the latter choice that offers the most promise to the nation in its effort to improve air quality and public health.