EXAMPLES OF HIGH RADIOACTIVITY IN CENTRAL APPALACHIAN HOMES

Many factors affect radioactivity concentrations in homes located over the geologically diverse materials of the central Appalachian states. In Virginia, studies over several years have identified situations where both airborne and waterborne radon greatly exceed EPA recommendations. In much of the Appalachian Piedmont Province, a quartz-mica schist has created and silt-sand soil averaging about 10 meters thick with a permeability and total-gamma radioactivity higher than surrounding soils. Almost 10,000 measurements of indoor radon in Virginia using three-month exposures of alpha-track detectors identified the schist as the terrane where more than half of the homes exceed the 4 pCi/L EPA recommended maximum when purchasing a home. Measurements of radon in the water supply to Virginia homes reveal that while municipal water supplies from reservoirs have radon concentrations of less than 100 pCi/L (EPA recommends less than 300 pCi/L in drinking water), homes using water wells average about 2500 pCi/L, and in our study some approach 10,000 pCi/L. It was also found that smaller homes using well water have much more airborne radon than larger homes. Consequently, the greatest risk from natural radioactivity is in smaller homes located over the schist.