Study of variation of indoor radon levels in houses and prediction of indoor concentrations using house characteristics and outdoor radon levels

The measurement of ²²²Rn concentrations in indoor and outdoor air was carried out in certain locations of Mandya city, Karnataka, using the Solid State Nuclear Track Detectors (SSNTD) technique. The annual mean values of ²²²Rn in indoor and outdoor are found to be 20.5 ± 1.4 and 9.0 ± 0.5 Bq m^-3, respectively. The observed mean value of indoor radon concentration is found to be well within the world and the Indian average of 40 and 42 Bq m^-3, respectively. Outdoor radon concentrations have been measured in the vicinity of houses where yearlong radon measurements carried out using the SSNTD technique. The seasonal variation in the outdoor radon was studied and the average concentrations during summer, rainy and winter are 9.1, 6.9 and 12.9 Bq m^-3 respectively. Considering the possible factors such as house characteristics (Volume, Surface area of building material, Leakage area, etc.), indoor-outdoor temperature difference and outdoor radon concentration into account, the indoor radon levels were predicted using the existing model which is based on the mass balance equation. The results are systematically analysed and discussed. The predicted values are compared with the measured values. (authors)