ever, important questions of equity in the treatment of the-two communities must be taken into consideration in the decision as to how to proceed.
A similar scenario can be envisioned in which some homes in a community are served by a public water supply and others have private wells. Under the provisions of the Safe Drinking Water Act (SDWA), the utility would be required only to provide water that meets the radon MCL to the homes that it serves. It is possible that the homes served by private wells would have some of the highest indoor-air radon concentrations. In a holistic view of achieving a comparable or greater health-risk reduction for the community, it might be best to remediate the air in the homes with the highest radon concentrations even if they are not served by the utility. However, that would present a dilemma for the utility because it would be mitigating homes to which it does not provide water. Such dwellings are outside the normal jurisdiction of the SDWA and therefore potentially outside the purview of a multimedia program. A policy decision would be needed as to whether such dwellings could be included in a multimedia mitigation program and would raise an important equity question, in that water ratepayers would be charged for the mitigation of homes that are not being served by their utility and whose occupants are not contributing to the payment of the costs of the radon-abatement program.
Another possible approach to reducing the indoor air concentrations of radon is to enlist homeowners in the identification and mitigation of homes with high radon concentrations. As previously described, home-mitigation programs will be practical only in areas of medium or high indoor-air radon potential or in communities with radon concentrations in the water supply that are close to the MCL. In this case, the utility might involve the community via a public-education program and potentially provide incentives for mitigation of those homes. The committee was asked to comment on the body of evidence regarding the effectiveness of such programs and on how the health-risk reductions could be evaluated in such cases. With respect to outreach and education programs, there is some experience that can be examined.
Communicating risk to the public such that individuals are motivated to change their behaviors and reduce their exposure to the hazard is a well-known problem. The report, Improving Risk Communication (National Research Council 1990b), addresses many of the issues relevant to that process. In particular, the report gives an example of comparing radon with other types of risk: ''radon risk can equal or exceed the 2% risk of death in an auto accident . . . for anyone who lives 20 years at levels exceeding about 25 picocuries per liter.'' This statement places an unfamiliar risk (radon exposure in homes) in juxtaposition to a more familiar risk (death in an auto accident). Though such techniques may help people understand the magnitude of an unfamiliar risk, it can also be misleading because