Assessment of Seasonal Variation of Indoor Radon Level in Dwellings of Some Districts of Azad Kashmir, Pakistan

Measurements of indoor radon concentrations in 200 dwellings of four districts of Azad Kashmir have been carried out using CR-39-based radon dosimeters. Indoor radon levels were calculated for four seasons (i.e. spring, summer, autumn and winter) in Muzaffarabad, Hattian, Neelum and Poonch districts. Maximum value of radon concentration (398 +/- 2 Bq.m(-3)) has been found in Muzaffarabad district (in bedrooms) and minimum value (23 +/- 9 Bq.m(-3)) is reported for Hattian district (in living rooms). Elevated values of radon levels have been found in winter, whilst lower values are observed in summer season. Seasonal correction factors calculated for spring, summer, autumn and winter seasons were found to be 1.02 +/- 0.91, 0.86 +/- 0.77, 0.98 +/- 0.92 and 1.14 +/- 1.04, respectively. Measured values for winter/spring, winter/summer and winter/autumn radon ratios were found as 1.11 +/- 1.28, 1.33 +/- 1.21 and 1.15 +/- 1.17. Radon doses have been calculated and yearly mean effective dose has been found 2.52 +/- 1.22 mSv, which is less than the lower limit of the recommended action level 3-10 mSv.