Inter-comparison of radon detectors for one to four week measurement periods

Seven different types of radon detectors (Atmos 12 dpx, RAD7, RStone, Sun Nuclear 1028, Ramon 2.2, Canary and CR-39) were compared for exposure periods of 1, 2, 3 and 4 weeks. The comparison was conducted under two conditions: (a) in a purpose-built radon chamber with an average radon concentration of 2560 Bq m(-3) (b) in a home environment with a radon concentration of 57 Bq m-3, in both cases measured by the reference detector (Atmos 12 dpx) with a +/- 10% uncertainty range. In (a) 5 out of 8 detectors recorded radon concentrations within the Atmos uncertainty range and all detectors recorded within +/- 15%; in (b) 3 out of 9 detectors recorded within the Atmos uncertainty range and 6 out of 9 measured within +/- 20%, for a 4 week measurement. The results from this study show that radon surveys can be conducted for shorter periods than the recommended 3 months where a rapid indication is needed of whether the radon concentration is above the reference level, such as when assessing the concentration during and after remediation work.