Indoor Radon and Radon Emanation in the Herculane Spa (Cerna Valley) Area - Romania

Recent investigations have shown a connection between high indoor levels of radon and lung cancer risk. The main source of the radon is the emanation from soil and ground water. A study has been carried out in the Herculane Spa region, where the highest level of radioactivity (226Ra and 222Rn) from geother mal waters in Romania has been measured. This paper presents data about the radon emanation rate and indoor radon concentrations measured in the area studied. Only 20% of the measurements of indoor radon concentrations were values above 200 Bq·m -3 (average 98 Bq·m -3 ) when the weather was warm but in the cold season 40% of the radon levels indoors (average 185 Bq·m -3 ) exceeded this value. For radon emanation rates we generally found values in the range 13-70 mBq·m -2 ·s -1 although they were significantly higher in the vicinity of the geological faults found in the area.