Estimation of indoor radon and thoron in dwellings of Palakkad, Kerala, India using solid state nuclear track detectors

Radon, thoron and their short lived progenies have a significant contribution to natural background radiation. Long term exposure of such radiation increases the probability of occurrence of cancer at low to moderate levels. The present study covers 25 dwellings in Pirayiri region of the Palakkad district, Kerala, India, using twin cup based dosimeter. The data analysis shows that geometric mean of radon gas concentration (25.52 Bqm−3) and thoron concentration (14.58 Bqm−3) are slightly higher than the nation wide average value. However, the radon gas concentration range is within the limit of UNSCEAR East Asian values. Annual Effective Inhalation Dose limit is less than the action level limit (3 mSv/y), recommended by International Commission on Radiological Protection (ICRP).