Inter-comparison of commercial continuous radon monitors responses

Indoor and outdoor (atmospheric) radon activity concentrations need to be measured as accurate as possible for radiation protection and for climate applications. Particularly radon concentrations below 100 Bq m −3, useful for the retrieval of radon prone areas and for atmospheric studies, still need a robust metrological chain to ensure their quality. Ones of the most common used commercial continuous radon monitors were compared here under slightly different environmental conditions. The measured data set were divided into two groups (< 100 Bq m −3 and ≥ 100 Bq m −3) to assess the monitors responses and their associated uncertainties. Nevertheless, these results should also to point out if commercial monitors are suitable for monitoring low atmospheric radon concentrations with an associated uncertainty of 10% (k=1). This work, carried out within the EMPIR 19ENV01 traceRadon project, aims to offer a starting point for the development of a future radon monitor as transfer standard to increase the metrological capabilities of atmospheric radon monitoring.