measurements of indoor radon, thoron and their progeny in farrukhabad city of uttar pradesh, india

background: more than 50% of the total dose received by human beings from all sources of radiation (both from natural and manmade) comes from radon and its progeny which is responsible for lung cancer in many cases. materials and methods: in the present study, the measurements have been carried out by using twin chamber dosimeter cups with lr-115 type-ii detectors. the value of track density of detectors gives the concentration of radon, thoron and their progeny in different modes. results: the average value of radon and thoron concentration was found 59 and 28 bq/m3, respectively. the inhalation dose was found to vary from 1.6 to 2.9 msv/y. the average value of paec for radon and thoron was found 6.4 mwl and 0.75 mwl, respectively. total annual exposure and annual effective dose varies from 0.23 to 0.39 wlm and 0.87 to 1.51 msv/y respectively. the values of life time fatality risk was found to vary from 0.68 x 10-4 to 1.18 x 10-4. conclusion: these measurements show that the radon/thoron concentrations and annual effective dose received by the population of the area are well below the action level recommended by the international commission on radiological protection (icrp). iran. j. radiat. res., 2012 10(3‐4): 193‐196