The U.S. EPA has financed more than 40 state, local, and tribal comparative risk projects. In them, participants collect the best data available about a wide range of environmental problems, then draw conclusions about the problems' relative seriousness. The task builds on EPA's risk assessment methods and technical data bases. People familiar with EPA's Unfinished Business and Reducing Risk⁴ projects may remember that the act of ranking environmental problems is problematic: the data are typically poor and participants must make difficult value judgments when comparing the seriousness of dissimilar risks, such as the effects of exposure to lead paint, the effects of exposure to ground-level ozone, and the potential effects of global climate change. EPA's original comparative risk projects were conducted largely by technical staff for internal consumption. States and cities have transformed the process into externally focused partnerships engaging scientists and non-scientists alike.

A typical comparative risk project today includes one or more technical committees composed of state or city agency staff people, private-sector scientists, and academics. The technical teams typically do the homework for the projects: collecting data and analyzing the risks posed by specific problems. The technical teams may rank the problems or they may turn their findings over to an executive-level committee to rank. A public advisory committee or steering committee is usually composed of senior government managers and the leaders of essential stakeholder groups: representatives of business and industry, the Farm Bureau, environmental coalitions, other civic organizations, and elected officials. These multi-disciplinary committees are essentially a hard-working, well-read surrogate for the public at large: a diverse group willing to take the time to work through more technical material than public debates usually surface. The committees are designed to strengthen the technical quality of the product, the public legitimacy of the results, and the political impact of the change recommendations.

One product of the comparative risk projects has been a ranked list of environmental problems. In general, the states have tried to turn that list into the basis for strategic plans and budget choices. Some states have developed specific short-term and long-term strategies to address high-risk problems. Others have tried to use the risk information and estimates of the costs of various policy options to select the most cost-effective strategies for reducing risk. The Carnegie Commission, EPA's Science Advisory Board, the National Academy of Public Administration, and others have endorsed this process of priority-setting in a time of scarce resources.

The comparative risk projects have demonstrated that the nation has not yet found or implemented effective tools for addressing serious long-term problems such as climate change, habitat destruction, and indoor air pollution. Perhaps just as significantly, the projects have refocused policy-makers' attention on the external