Radiation Measurements 43 (2008) S385 – S388 www.elsevier.com/locate/radmeas Study of indoor radon and its progeny levels in rural areas of North India using LR-115 plastic track detectors M. Shakir Khan, A.H. Naqvi, Ameer Azam ∗ Department of Applied Physics, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh 202002, India Abstract This paper presents the values of potential alpha energy concentration (PAEC) and concentration of radon measured in 51 houses of four Indian villages. The value of PAEC varies from 2.1 ± 0.2 to 300.8 ± 2.6 mWL with a geometric mean value of 29.7 ± 0.8 mWL. The value of the concentration of radon varies from 19.4 ± 1.9 to 2782.6 ± 23.7 Bq/m 3 with a geometric mean value of 255.5 ± 7.1 Bq/m 3 . The values of effective dose are found to vary from 0.34 ± 0.03 to 48.11 ± 0.41 mSv/yr with a geometric mean value of 4.8 ± 0.12 mSv/yr. Most of the values have been found to be higher than the values in urban dwellings. © 2008 Elsevier Ltd. All rights reserved. Keywords: PAEC; Radon; Effective dose; LR-115; Plastic detectors 1. Introduction Radon and its short-lived progeny are the most impor- tant sources of ionizing radiation found in our environment, which are probably responsible for causing adverse effects on human lungs. Inhalation of radon and its short-lived alpha active progeny ( 218 Po and 214 Po) present in the ambient air contributes significantly to the radiation damages caused in tracheal, bronchial and pulmonary regions. Studies have shown that prolonged inhalation of radon and its progeny may lead to lung cancer in many cases (Lundin et al., 1971; Sevc et al., 1976; Ramachandran et al., 1988). Presently, the natural ra- dioactive radon gas is considered to be the second most impor- tant cause of lung cancer after smoking. Living for lifetime in a house where radon is at the Action Level of 200 Bq/m 3 carries a 3–5% risk of fatal lung cancer (NRPB, 2000). Measurement of indoor radon and its progeny levels in human dwellings, therefore, has become very important from health physics point of view. Nationwide surveys have been conducted in many advanced countries to find the radon levels in various kinds of houses (Cohen, 1975; Jonsson, 1988; Langroo et al., 1991; Kendall et al., 1994). In India, too, there had been a plea for ∗ Corresponding author. Tel.: +91 931 978 8742. E-mail address: azam222@rediffmail.com (A. Azam). 1350-4487/$ - see front matter © 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.radmeas.2008.03.026 national effort on monitoring environment radon (Subba Ramu et al., 1991). We have been measuring the levels of radon and its progeny for the last about 15 years, but most of the measurements have been carried out in urban areas. It is for the first time that we have started measurements in rural areas. In the present investigations, levels of indoor radon and its progeny have been measured and effective dose has been calculated in the indoor environment of 51 houses situated in four villages of the Etah district of Uttar Pradesh province in Northern India. 2. Experimental details LR-115 type II plastic track detectors of size 2 × 1.5 cm were used as passive detectors in “BARE” mode (Alter and Fleischer, 1981) for recording the tracks of alpha particles emitted by 222 Rn gas present in our ambient air and also its short-lived progeny, typically 218 Po and 214 Po, which gen- erally attach themselves to the aerosols. The detectors were fixed on cards and mounted on the walls inside bed rooms at a height of about 160 cm from the ground with their sensitive surfaces facing the air, taking due care that there was nothing to obstruct the detectors within a hemispherical volume of radius 9.1 cm in front of them. The BARE mode of exposure is generally suspected to suffer from interferences due to dust