Indoor radon in Tunisian spas

Indoor radon concentrations were measured in four well-known spas of Tunisia using nuclear track detectors. The radon concentrations in these spas were found to be in the range of 19 − 870 Bq.m-3. The equilibrium factor F between radon and its progeny was found to vary in the range of 0.2 0.5, depending upon the ventilation rates within the buildings of the spas. Using the exposure-dose conversion factor, the effective doses to patients and workers were estimated and the dose was found to vary in the range 3.7 × 10-3 − 12.5 × 10-3 mSv.y-1 and 0.45 − 1.5 mSv.y-1 for patients and workers, respectively. These values are well inside the limit recommended for the annual dose limit of 20 mSv.y-1 for an occupational worker. The radium content in the groundwater of all four spas was measured and the results showed no correlation between the 226Ra concentration in water and radon concentration in indoor air of the investigated spas.