Environmental radon studies using solid state nuclear track detectors

The results of radon activity recorded in 70 dwellings of Nurpur area, Kangra district, Himachal Pradesh, India are reported. LR-115 Type 2 films in the bare mode were exposed for four seasons of three months each covering a period of one year for the measurement of indoor radon levels. The calibration constant of 0.020 tracks cm−2 d−1 per Bq m−3 has been used to express radon activity in Bq m−3. The annual average indoor radon concentrations in 17 different villages of the area are found to vary from 168±46 to 429±71 Bq m−3. Most of the indoor radon values lie in the range of action levels (200–600 Bq m−3) recommended by International Commission on Radiological Protection.