An etched track detector for short-term screening measurements of radon

Abstract

An etched track detector has been developed for use in screening or indicative measurements ofradon in homes over an exposure period of 14 days. If the annual mean radon concentration estimatedfrom screening detector results is within a factor of two of the UK radon Action Level (200 Bq m−3), the householder is told that the result is uncertain, and advice on whetherthe home is above or below the Action Level must be based on the result of a(standard) 90 day measurement. The screening detectors are always supplied tohouseholders together with detectors to be exposed for 90 days, so that if thescreening result is reported as being uncertain (within the range 100–400 Bq m−3), a long-term measurement in the home is already under way. Comparison of the results ofthe screening (14 day) and standard (90 day) detectors exposed in the same homes showsthat reporting screening results in this way did not result in any householdersbeing wrongly advised. Short-term measurements can therefore be offered in thosecircumstances where a householder needs a faster indication of radon levels in aproperty (for example a house sale), with the caveat that a 14 day exposure resultwithin a factor of two of the Action Level requires a long-term measurement toconfirm whether the dwelling is above or below the Action Level. A precautionaryuncertainty range for use with charcoal detector measurements is also given (75–500 Bq m−3).