Precision Field Study and Radon Chamber Test of a New Alpha-Track Monitor

Abstract

Concern about the risk of lung cancer associated with residential exposure to radon (Rn) has led the U.S. Environmental Protection Agency (U.S. EPA) to recommend that all homes be tested for Rn. There is also concern, however, about the precision of Rn detectors at the Rn concentrations expected in houses, particularly around 4 pCi/L, the U.S. EPA action level. A new alpha-track monitor was evaluated in a 1-month precision field test in which 12 sets of 3 monitors were deployed in each of 4 homes (total of 48 sets, 144 monitors). The coefficient of variation (CV) averaged 12 percent at mean Rn concentrations of ≥ 4 pCi/L. In a Rn chamber test simulating a Rn concentration of ∼ 10 pCi/L, the overall CV for 69 monitors was 8 percent and the recovery ratio (mean measured concentration/reference concentration) was 97 percent. Spatial variability data from the field study showed that basement Rn concentrations exceeded first-floor values, as in previous studies. Other differences in Rn concentration due to monitor placement (room-to-room, high versus low) were inconsistent.