Instruments to measure radon-222 activity concentration or exposure. 20. interlaboratory comparison and proficiency testing 2023

The German government has entrusted the Federal Office for Radiation Protection (BfS) to operate measures for quality assurance of radon measurements concerning the radiation protection at workplaces. To a large extent, these measurements concerning the radon activity concentration in air or the individual exposure are performed with exposimeters, that is to say non-electronic measurement instruments. The quality of their results is typically assured by participation in interlaboratory comparison and proficiency testings as offered by BfS since 2003. Here, a number of measurement instruments are exposed in a controlled way in the BfS Radon calibration laboratory. After the evaluation of the exposimeters by the participants the results are compared to the BfS reference value. The performance is evaluated as "satisfactory", if the deviations of the measurement values from the reference value remain within a pre-defined range. The evaluation of performance is based on findings from previous interlaboratory comparisons for exposimeters and the expected performance based on scientific evaluation. Thus, institutions offering radon measuring services can demonstrate the effective operation of their quality management system and procedures. This allows public and private customers to get a general idea on the performance of radon measuring institutions using exposimeters. This report presents the results of the 20th BfS interlaboratory comparison and proficiency testing, which was performed in 2023. The group of participants comprises measuring bodies according to section 169 of the Radiation Protection Act and recognised bodies according to section 155 of the Radiation Protection Ordinance as well as annually changing measuring institutions from all over the world. The report lists the participating measuring institutions and summarizes the pseudonymised results of the interlaboratory comparison and proficiency testing. In 2023, 39 of 42 instrument sets from participating institutions have shown a satisfactory performance in proficiency testing. This includes all of the 12 sets of measurement instruments of the participating measuring bodies and recognized bodies. These exposimeter types are operated at workplaces in Germany. Individual reports were sent to the participating institutions for quality assurance purposes. Comprehensive Reports on previous BfS interlaboratory comparison and proficiency testings have been published in the online repository DORIS.