Seasonal Variation of Indoor Radon (222Ra) and Thoron (220Ra) in the Dwellings of Bathinda District of Punjab, India

Seasonal concentrations of indoor radon and thoron have been measured in 12 villages (selecting four dwellings in each village) situated in Bathinda district of Punjab, using pin hole based twin cup dosimeters. The radon concentration varied from 20.02±6.08 to 34.97±2.84 Bq m-3 in rainy, 33.07±1.21 to 50.14±4.91 Bq m-3 in winter, 18.38±6.05 to 54.34±28.84 Bq m-3 in spring and 9.02±4.78 to 26.97±20.17 Bq m-3 in summer time with an average value of 27.73±6.32, 43.27±5.97, 32.20±14.66 and 18.7±11.97 Bq m-3, respectively. Indoor thoron concentration varied from 11.06±5.39 to 47.39±36.29 Bq m-3 in rainy, 7.98±5.90 to 36.76±19.79 Bq m-3 in winter, 11.60±5.97 to 76.69±87.28 Bq m-3 in spring and 10.59±6.78 to 61.37±45.43 Bq m-3 in summer time with an average value of 23.39±15.86, 23.48±10.94, 31.31±22.69 and 28.71±16.36 Bq m-3, respectively. The overall average annual effective radiation dose, to the occupants of the dwellings, corresponding to radon and thoron is 0.88±0.28 mSv y-1 and 0.66±0.40 mSv y-1, respectively. An attempt has also been made to find the possible seasonal relationships of indoor radon/thoron concentrations with surface to volume ratio, ventilation conditions and building construction materials of dwellings. Consequently, some contrasting results have been obtained between the behavior of radon and thoron.