Activity concentrations of the thoron and radon progenies Pb-212 and Pb-210 in the healing gallery of Badgastein, Austria

In the healing gallery of Badgastein (Austria) aerosol samples were collected with cascade impactor devices and Pb-210 and Pb-212 activity concentrations were measured by liquid scintillation counting. Simultaneously Rn-222 was determined with a Si surface barrier detector. At different ventilation rates of the gallery, Pb-210 concentrations ranged between 4.6 and 730 mBq m(-3), while Pb-212 values were between 760 and 7230 mBq m(-3). The highest Pb-212/Pb-210 ratio of 165 was found during full ventilation, when Rn-222 and Pb-210 levels dropped considerably. The lowest ratio of 10 was measured after a few months of patients' treatment, when very high Rn-222 levels of up to 350 kBq m(-3) and the maximum Pb-210 level were reached. Taking into account the particle sizes of the aerosols, we observed that the Pb-212 activity distribution was shifted towards smaller particle sizes compared to the Pb-210 distribution.