Intercomparison 2003 for Radon measurement services at PSI

Twelve radon measurement services participated in the 2003 Radon Intercomparison Exercise performed at the Reference Laboratory for Radon Gas Activity Concentration Measurements at Paul Scherrer Institut (PSI) during March 13th to 24th, 2003. Ten of these laboratories were approved by the Swiss Federal Office of Public Health and their participation in the intercomparison exercise was a requirement to warrant quality of measurement. Radon gas detectors (etched-track and electret ionisation chambers) and instruments (ionisation chambers and electrostatic precipitation) were exposed in the PSI Radon Chamber in a reference atmosphere with an average radon gas concentration of 1950 Bqm sup - sup 3 leading to a radon gas exposure of 517 kBqhm sup - sup 3. Additional five electret-detectors of an approved measuring service were purchased by the Swiss Federal Office of Public Health for a spot check. Two of these were exposed as described above, two had an exposure of 247 kBqhm sup - sup 3 at an average radon concentration of 1960 Bqm sup - sup 3 and another was used as transport detector. The results of these detectors showed a larger difference to the target value and a larger standard deviation than the detectors submitted for the intercomparison exercise by the measuring service. The unexposed transport detector showed a notedly too high signal. For the first time in this series of intercomparisons, no open etched-track detectors participated. Thus, the generation of aerosol particles with burning candles was not necessary.