Intercomparison exercise of the PTB, BfS, MPA and PSI calibration facilities for radon gas concentration

The traceability chain of one national reference laboratory (PTB) and three accredited radon calibration laboratories (BfS MPA and PSI) to internationally acknowledged radon gas standards is specified. As an additional tool for quality assurance, interchange of an electronic radon measuring instrument was used as a means for a relative comparison of the radon gas reference atmospheres. The instrument was exposed to radon gas activity concentrations between 500 Bq.m(-3) and 15 kBq.m(-3). Measured sensitivities of the participants agree well inside the range of specified calibration uncertainties.