LAUSR

Purpose Report the experience of Medical Physics Department of APSS Trento in coordinating the assessments and radioactive radon gas mitigations of medical clinics, complying with laws [1] , [2] . Methods and materials 42 measurement points were chosen in the workplaces at the lower floors (undergrounds, basements, ground floors) of the various buildings that were representative of the most critical situations with respect to aeration.  Radon concentrations have been measured for one year through all workplaces using passive detectors, i.e. electrets giving integrated values, and also during Radon mitigation, using active detector, i.e. a Lucas scintillation cell monitor, allowing temporary monitoring. For each worker the effective dose was estimated applying the conversion factor 3·10−9 Sv·m3/Bq ·h [2] . Based on Radon concentration measurements and effective dose estimations, an evaluation of Radon mitigation has been undertaken (Fig. 1), adopting organizational or structural approach. Results The exceeding of the action levels [2] have been found only at medical clinics of Pinzolo and Levico, in terms of both concentration and effective dose. At Pinzolo a Radon concentration of 1745 Bq/m3 was measured, while at Levico it was found to be 1216 Bq/m3. Two different remedial actions were adopted. At Pinzolo an organizational approach was undertaken. Workers were transferred to another workplace at ground floor with a formwork for ventilated foundation, where the Radon concentration was 160 Bq/m3. Instead at Levico, considering also additional measurements in other places of the same building, an active soil depressurization through mechanical ventilation has been realized, leading to a Radon concentration less than 110 Bq/m3. The optimization of ventilation system was done using active dosimeters. Conclusion Although Radon mitigation is a challenging task, the adopted solutions proved to be effective.