seasonal variation of radon, thoron and their progeny levels in dwellings of haryana and western uttar pradesh

background: radon and thoron are invisible, odorless, heavy and radioactive gases which are ubiquitously present in dwellings and in the environment. in the present work, seasonal variation of indoor radon, thoron and their progeny concentrations has been studied in the dwellings of industrially polluted cities in district faridabad, haryana and district mathura in uttar pradesh. materials and methods: lr -115, type- ii (kodak pathe, france), peelable, plastic track detectors commonly known as solid state nuclear track detectors (ssntds) were used to measure the radon thoron concentration over long integrated times. the measurements were carried out in the mixed field of radon and thoron and the detectors were exposed for about 90 days. results: the average value of radon and thoron concentration in the dwellings varied from 23.5 bq/m3 to 65.2 bq/m3 and 9.8 bq/m3 to 18.7 bq/m3 respectively in different seasons. the average annual exposure and annual effective dose in living rooms due to radon and thoron progeny was estimated to be 0.195 wlm (working level month) and 0.74 msv respectively. the average life time fatality risk of lung cancer from the chronic radon and thoron progeny exposure was estimated to be 5.8 ´ 10-3 (0.58%). conclusion: the seasonal variations of measured radon levels in the environment of lpg bottling plant, radon-thoron levels and inhalation dose due to radon and thoron and their progeny in dwellings indicate that the levels were higher in winter (october to january) than in summer (april to july). iran. j. radiat. res., 2009 7 (2): 79-84