facilities. When the first round of waiver applications were submitted, most were from large cities that were well organized and could afford to prepare the required environmental-impact assessment. A similar phenomenon could happen with the proposed multimedia approach to radon mitigation, especially if a state chose not to submit such a program to EPA. In this case, the law allows individual public water supplies within a state to submit their own multimedia mitigation programs. It is likely that many very small water utilities whose water contained radon concentrations exceeding the MCL but not the AMCL could not muster the resources or mount the effort required to propose such a program formally. EPA, state agencies, and perhaps the water associations should develop mechanisms to assist small public water supplies in decision-making regarding multimedia mitigation programs.

In the 1991 proposed rule for radon in drinking water, EPA outlined a set of monitoring requirements for establishing and maintaining compliance with the MCL. The agency recommended that systems that must treat their water for radon be required to sample annually to demonstrate compliance. If the water did not meet the MCL, the sampling frequency would be increased to quarterly until the average of four consecutive samples was less than the MCL. The goal of compliance monitoring is to ensure that there is a continued measurable health-risk reduction due to the removal of radon from drinking water. If a multimedia approach were used in which the air in specifically targeted homes is mitigated for radon, the water utility would have to monitor the indoor airborne-radon concentrations in the mitigated dwellings to ensure a continued measurable health-risk reduction. The monitoring requirement should be similar for any new houses built to be radon-resistant. The committee recommends that air-compliance monitoring be required in each home whose air is mitigated and that these compliance requirements be equivalent to the requirements established in the final rule that regulates radon in drinking water.

Summary

A number of important issues will need to be considered by any state agency or local water utility before it proposes the implementation of a multimedia mitigation program. The ease with which dwellings with high indoor radon concentrations can be found within the utility's service area is important because it will mean that houses that can be potentially mitigated can be more easily identified. In addition there will be a large health-risk reduction associated with each mitigated house. At the same time, the smaller number of houses that are mitigated to obtain the same or greater health-risk reduction as would occur from treating the water will also increase the equity issues in that fewer individuals will benefit from the multimedia mitigation program relative to the number being asked to share the remaining risk. Public education will certainly be needed to obtain a community's commitment to the multimedia program and here again,



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