Environmental radioactivity: a case study in Himachal Pradesh, India

A radon survey has been carried out in the soil-gas and indoor air of some villages situated in the vicinity of areas known for uranium mineralisation in Himachal Pradesh (H.P.). Both active and passive techniques were used for radon monitoring inside the dwellings. The highest value, 75 400±2620 Bq m-3, of radon in soil-gas was found in the village of Samurkhurd. The mean values of indoor radon concentration for the village of Ramera, Asthota, and Galot were found to be 249±14, 200±16 and 161±13 Bq m-3, respectively. The average annual exposure doses due to radon and its daughter products to the inhabitants of these villages amount to 4.3±0.2, 3.4±0.3 and 2.8±0.2 mSv, respectively. Indoor radon levels are within the safe limits in most dwellings but call for mitigation of the radon health hazard in some others. A radon and helium survey of thermal springs in the Parbati and Kullu valleys of Himachal Himalaya was also carried out. The maximum values of radon (716.3 Bq l-1) and helium (90 ppm) activities were recorded in a thermal spring at Kasol in Parbati valley. In general, high radon and helium values are correlated with high uranium concentrations in the soil of the area in the environs of the thermal springs.