DISTRIBUTION OF 222RN LEVELS IN INDIAN DWELLINGS

Measurements of indoor radon concentrations in about 150 dwellings of Kohima (Nagaland), Baijnath and Palampur (Himachal Pradesh) and Dehrad un (Uttar Pradesh) were carried out to assess the variability of expec ted exposure of the population to radon and its progeny. The geometric mean values of the radon concentrations for 65 dwellings in Kohima, 4 3 dwellings in Palampur and Baijnath, and 34 dwellings in Dehradun mea sured by LR-115 type II detectors were 88 Bq.m(-3), 134 Bq.m(-3) and 5 7 Bq.m(-3) with geometrical standard deviations of 1.7, 2.3 and 1.7 re spectively. The radon distribution in Kohima was found to be approxima tely log-normal; however, the radon distribution in Palampur and Baijn ath (H.P.) and in Dehradun (U.P.) seems to be bi-modal. The mean annua l effective doses from inhaled radon daughters in Kohima, Palampur and Baijnath, and Dehradun are estimated to be 1.5 mSv, 2.3 mSv and 1.0 m Sv respectively.