USE OF COMMERCIAL RADON MONITORS FOR LOW LEVEL RADON MEASUREMENTS IN DYNAMICALLY OPERATED VOC EMISSION TEST CHAMBERS

Compared to the intended EU reference level of 300 Bq m(-3) for indoor radon concentrations, the contribution of building materials appears to be low. Considering the recommended limit of 100 Bq m(-3) by WHO, their contribution is supposed to be relevant, especially at low air exchange rates. This study as part of a two-part research project investigated the suitability of direct low level Rn-222 measurement under simulated indoor conditions with commercial radon monitors and dynamically operated emission test chambers. Active measuring devices based on ionisation or scintillation chambers with 1-sigma uncertainties below 8.6% at 20 Bq m(-3) were found to be best suitable for a practical test procedure for the determination of radon exhalation rates of building materials. For the measurement of such low concentrations, the knowledge of the accurate device background level is essential.