Radiological variation of indoor radon and thoron levels by pinhole dosimeter in different seasons

The annual variation in radon and thoron concentrations in different seasons has been revealed for 40 different locations of Jodhpur, Nagaur, Bikaner and Jhunjhunu districts of Northern Rajasthan by using pinhole dosimeter, and the results have been compared with ventilation conditions and building materials. The indoor radon concentration was observed to vary from 109？±？17 to 334？±？13？Bq？m？3, 63？±？17 to 255？±？21？Bq？m？3, 45？±？11 to 128？±？19？Bq？m？3 and 74？±？9 to 300？±？21？Bq？m？3 and thoron concentration varies from 26？±？15 to 418？±？21？Bq？m？3, 3？±？2 to 134？±？33？Bq？m？3, 12？±？6 to 140？±？19？Bq？m？3 and 6？±？4 to 408？±？29？Bq？m？3 for winter, spring, summer and autumn seasons, respectively. In winter season, indoor radon concentration of about 50% dwellings was observed to be within or higher than the action level as recommended by International Commission of Radiation Protection. However, in summer the action level is lower than the action limit. The exposure of human beings to indoor radon and thoron and the associated risk has also been examined. The total annual mean effective dose due to indoor radon and thoron in Northern Rajasthan are less than or close to the action level 3–10？mSv？y？1 as recommended by International Commission of Radiation Protection