ABOVE-AVERAGE RADON RISK IN SMALL PRIVATE WELL HOMES

A study of @1000 homes in northern Virginia and central Maryland revealed that three-month measurements of indoor radon were between 1-40 pCi/L (US-EPA MCL is 4 pCi/L for home purchases, and 2 pCi/L for long-term occpancy). Most homes exceeded 2 pCi/L. Homes with private wells had waterborne radon between 100-8,000 pCi/L, averaging @2000 pCi/L (US-EPA MCL for potable water is 300 pCi/L). In large homes, no correlation exists between waterborne radon and airborne (i.e., indoor) radon, but for small homes, increasing waterborne radon results in increasing airborne radon. In a typical small home with a private well, a greater health risk comes from waterborne radon than from the soil-gas (under-the-home) radon.