International intercomparison and quality assessment of passive and active 222Rn measuring devices in the Asia-Pacific region

Intercomparison exercise is an integral part of the quality assurance programmes in 222Rn measurements using active and passive devices. Ensuring the accuracy of data generated through measurements necessitates periodic performance checks. To achieve harmonization of methods, quantify biases and errors in measurements, and identify the reasons for discrepancies, there is a pressing need for periodic intercomparison exercises. To address this need of numerous laboratories, particularly in the Asia-Pacific region, a calibration facility for 222Rn measuring devices has been established at the Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, India. An international intercomparison exercise for the 222Rn measuring devices was conducted at this facility in the year 2022 with the participation of 10 laboratories from six countries. A total of 354 devices (comprising of both active and passive detectors) were subjected to intercomparison measurements by exposing them to three concentration levels: (5.97 ± 0.29) × 103 Bq m−3, (0.70 ± 0.09) × 103 Bq m−3 and (2.02 ± 0.20) × 103 Bq m−3 in separate experiments and the exposure durations were 7 days, 15 days, and 10 days respectively. The performance of each laboratory was evaluated following the criterion adopted by the International Atomic Energy Agency (IAEA) in its worldwide proficiency test programmes. This exercise brought out the fact that some of the laboratories need to improve their measurement practices to produce reliable data. •An international intercomparison exercise for 222Rn measuring devices was conducted.•Ten laboratories from six countries participated and 360 devices were used.•Devices were exposed to 222Rn concentrations of 5967, 699, and 2021 Bq m-3.•Certain laboratories encountered challenges in generating reliable data.•From the lessons learned laboratories can enhance their measurement capabilities.