it does not specify the respective or acceptable levels of exposure, leaves out potentially relevant nonlethal consequences, and uses language (picocuries per liter) unfamiliar to most people. The comparison above is an example of an expert's message that is precise and accurate but is too complex, or uses unfamiliar technical jargon, such that only another expert would likely understand it. In contrast, simplified messages that nonexperts can understand usually present only selected information, thus, they can be challenged as inaccurate, incomplete, or manipulative.

There have been limited studies of the effectiveness of communicating the risk of radon to the public though little has been peer-reviewed and openly published. A useful summary of state programs to determine the effectiveness of radon programs in mitigating individual risk was prepared by the Conference of Radiation Control Program Directors (1996). Following various types of state outreach programs, CRCPD determined through surveys that a total of 73% of the participants recognized radon, 52% considered radon to be unhealthy, and 44% defined radon correctly. Only 10% of the survey participants tested for radon in their homes, and only 16% of those who thought radon was unhealthy tested their homes. Surveys revealed that radon tests took place for other reasons. For example, 26% of the tests were associated with real-estate transactions though 18% of the tests were carried out despite that residents did not believe radon was unhealthy. The CRCPD surveys indicated that states with radon testing as part of their real-estate transactions requirements also had high-awareness. Furthermore, the surveys indicated that home mitigation was lower for homes with indoor air concentrations less than the EPA-recommended action level of 150 Bq m-3.

It is clear from the CRCPD surveys that certain state radon programs were more effective in communicating risk to the public and that Maine had the greatest success. In Maine, a total of 5% of all homes have been mitigated and 30% of homes with radon levels above average have been mitigated. Of homes that had radon in water at over 370,000 Bq m-3, more than 75% have been mitigated, even though the state of Maine has recommended for the last 20 years that homeowners should mitigate water at levels greater than 740,000 Bq m-3. Factors in Maine which seem to be related to that success include partnering between state agencies and local groups and authorities, and effective use of the media. Wyoming also had high awareness; similar partnering activities were used there as well as using the media to promote radon awareness including outdoor advertising on billboards, direct mail, newspapers, and television publicity. The District of Columbia and Texas had the largest increases in radon awareness at 6% each. The District of Columbia distributed radon information in English and four other languages.

Mitigation of residences for high radon levels varied among the states from 3.6% in Pennsylvania to 0.3% in Hawaii. The states with the highest mitigation rates also were the top 25% of states in terms of public radon awareness. These states provided advice and assistance by telephone as well as printed materials,



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