COMPILATION AND INTEGRATION OF STUDIES OF RADON LEVELS IN UNITED-STATES HOMES BY STATES AND COUNTIES

The final compilation of mean radon levels in U.S. counties from the University of Pittsburgh data base is presented. It is derived from 272,000 measurements satisfying bias reduction criteria, and gives means for 1217 counties in 49 states after properly combining data from basements and upper floors. EPA data tapes were analyzed to separate basements and upper floor measurements and these were properly combined to derive mean radon levels from 1141 counties in 39 states based on 40,000 measurements. State-sponsored studies in Florida, New Jersey, South Carolina, New Hampshire, New York, Iowa, Idaho, Ohio, and Utah also are utilized, after appropriate analysis in some cases, to give mean radon levels in 391 counties. All data sets are renormalized to give a national average in agreement with the National Residential Radon Survey. Correlations among the various data sets were studied to estimate uncertainties in each. A combined data set is then assembled, giving best estimates of average radon levels in homes in 1705 counties.