Comparison of indoor radon and thoron concentrations in the urban and rural dwellings of Chhattisgarh state of India

In the frame of nationwide radon/thoron monitoring program, indoor radon/thoron and their progeny concentrations have been estimated for 210 dwellings situated in 8 towns (urban) and 9 villages (rural) of Chhattisgarh state of India. The measurement has been made on quarterly integrating cycle for one full year in each dwelling. Twin chamber dosimeter cup with LR-115 Type-II Solid State Nuclear Track Detector was used for the measurement of indoor radon/thoron concentration. The results show that the geometric mean of indoor thoron concentration in urban dwellings varies from 11.57 to 25.88 Bq m(-3) with an overall geometric mean value of 16.65 Bq m(-3), while in rural dwellings it varies from 12.50 to 30.08 Bq m(-3) with an overall geometric mean value of 19.00 Bq m(-3). The potential alpha energy concentration (PAEC) levels of thoron in the urban and rural dwellings are found to be 2.58 and 4.57 mWL, respectively. Similarly, the geometric mean of indoor radon concentrations in urban dwellings is found to vary from 20.20 to 30.13 Bq m(-3) with an overall geometric mean value of 25.28 Bq m(-3), while in rural dwellings it varies from 15.50 to 36.05 Bq m(-3) with an overall geometric mean value of 27.32 Bq m(-3). The PAEC levels of radon in the urban and rural dwellings are found to be 1.50 and 1.87 mWL, respectively. The dose contribution of thoron and progeny in total inhalation dose has been found to be more than 20% in all the surveyed places that show the necessity to pay attention to the presence of thoron and progeny from public health point of view. (C) 2008 Elsevier Ltd. All rights reserved.