Radiation dose due to radon, thoron and their decay products in indoor environment of Khurja City, U.P., India

Inhalation of radon, thoron and their decay products can cause a significant health hazard when present in enhanced levels in the indoor environment like a human dwelling. In the present work a set of indoor radon and thoron measurements was carried out using time-integrated passive twin cup dosimeters containing LR-115 Type II solid state nuclear track detectors in different houses of Khurja City in Bulandshahar district of U.P. in India, built of the same type of building materials. The radon gas concentration was found to vary from 9.18 to 23.19 Bq m−3 with an average value of 16.02 Bq m−3 (SD = 3.68) and the thoron gas concentration varied from 2.78 to 9.03 Bq m−3 with an average value of 5.36 Bq m−3 (SD = 1.58). The radon progeny concentration ranged from 0.99 to 2.51 mWL with an average value of 1.77 mWL (SD = 0.40) and the concentration of thoron progeny was found to vary from 0.30 to 0.98 mWL with an average value of 0.58 mWL (SD = 0.17). The annual effective dose varied from 0.27 to 0.67 mSv year−1 with an average value of 0.47 mSv year−1(SD = 0.10).