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

An etched track detector has been developed for use in screening or indicative measurements of radon in homes over an exposure period of 14 days. If the annual mean radon concentration estimated from 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 whether the 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 to householders together with detectors to be exposed for 90 days, so that if the screening 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 of the screening (14 day) and standard (90 day) detectors exposed in the same homes shows that reporting screening results in this way did not result in any householders being wrongly advised. Short-term measurements can therefore be offered in those circumstances where a householder needs a faster indication of radon levels in a property (for example a house sale), with the caveat that a 14 day exposure result within a factor of two of the Action Level requires a long-term measurement to confirm whether the dwelling is above or below the Action Level. A precautionary uncertainty range for use with charcoal detector measurements is also given (75-500 Bq m-3).