Measurement of indoor radon concentration and assessment of doses in different districts of Northern Rajasthan, India

Radon (Rn-222), the immediate decay product of radium, is a causative agent of lung cancer. The seasonal indoor radon concentration in houses with different floorings, walls and roofs has been measured in Northern Rajasthan, India. The measurements were made in 100 houses using LR-115-type II plastic track detectors over four successive three-month periods (winter, spring, summer and autumn). The mean values of indoor radon concentrations in winter, spring, summer and autumn were determined to be: 176Bqm(-3), 131Bqm(-3), 120Bqm(-3) and 151Bqm(-3), respectively. The annual average indoor radon concentrations in the dwellings were found to vary from 117 to 215Bqm(-3) with an average of 144Bqm(-3). In approximate to 10% of the dwellings the indoor radon activity concentration values lies in the range of action level (200-300Bqm(-3)) recommended by International Commission on Radiological Protection. The annual effective dose received by the residents of the study area varied from 2.0 to 3.67mSv with an average of 2.46mSv. The seasonal variation in indoor radon reveals the maximum value in winter and minimum in summer. The influences of the factors linked to building characteristics in relation to radon measurements were examined.