Radioactivity in balneotherapy in Hungary and Slovenia

In Hungary and Slovenia a lot of thermal water occurrences providing mineral water for spas are used for curative therapeutic purposes in cases of locomotor and gastrointestinal diseases. In these balneotherapeutic facilities the atmosphere can contain radon and radon daughters at high concentrations. Radon diffusing from the pores and cracks of the minerals being dissolved in underground waters is taken up by spa wells and in the spas the radon emanates from the water. In the premises of balneotherapy workers can sometimes be exposed to radiation at levels, comparable to those of uranium miners. The aim of the study was to identify the site-specific radon sources, variation of the radon concentration, and to estimate the dose to the personnel, patients and visitors of these facilities from the radon daughters. Sampling was performed in intervals, sufficient to reveal diurnal and seasonal variations of radon concentrations. By simultaneous radon and radon progeny measurements (Pylon Electronics Inc. AB-5 type monitors, CPRD passive radon detector and AEP-47 working level detector, and SARAD 3020) the equilibrium factor was usually about 0.5, this value was used in dose calculations. Besides, nuclear track and electret detectors were used for long-term integrated
measurements of radon concentrations (Radamon, E-perm). From the mean radon concentrations cumulative WLM exposures, bronchial dose and effective dose equivalent values were calculated for the staff and visitors. Systematic diurnal variations of radon concentrations were found in some thermal spas. The diurnal variations of the radon levels were attributed to the technology of operation of the bath. It was
shown, that the ventilation can significantly reduce the radon concentration at balneotherapeutic workplaces. The effective dose equivalent values for the spa personnel generally do not exceed the 20 mSv per year limit, recommended for workers by the ICRP 60 publication. In cases when calculated dose was higher, the management of the bath was recommended to introduce a more effective ventilation system or reduce the occupancy in the high radon atmosphere. The doses for visitors and patients were one or two magnitude lower, than that of the personnel.