Study of indoor radon, thoron and their decay products level in residences of Udham Singh Nagar district of Uttarakhand, India

Tendency of radioactive radon gas to accumulate within the indoor environment can cause serious hazard to person. Presented study has been carried in 102 houses of district Udham Singh Nagar of Uttarakhand. Gaseous radon and thoron levels were measured with pinhole twin cup dosimeters, and decay products were measured with progeny sensors (DTPS/DRPS). LR-115 (SSNTD) was used as a detector in both techniques. The average radon and thoron values (in Bq m −3 ) were found to be 36.7 ± 9.5 and 48.8 ± 21.2, respectively. The radon and thoron progeny were found to be 17.1 ± 4.5 and 1.7 ± 0.5 Bq m −3 , respectively. The concentration of radon/thoron and progenies were estimated in different seasons and doses were also calculated by applicable formulae. The total annual effective dose (in mSv year −1 ) due to inhalation of radon, thoron and their progenies concentration was found at 1.64 ± 0.34.