levels of natural radioactivity in environment in residential area of moradabad district, western uttar pradesh

indoor radon and thoron have been measured in the houses ofmoradabad district, uttar pradesh india, by means of solid state nuclear trackdetectors. radon, an invisible radioactive gas, occurs naturally in indooratmospheres and along with thoron is the most important contribution of humanexposure to natural sources. radon exists in soil gas building materials and indooratmosphere to name but a few. risk of lung cancer depends on the concentrationof radon and thoron and their decay products in the environment aboverecommended levels. the present article measures the concentration of indoorradon and thoron in 60 dosimeters by means of a solid state nuclear track detectorin different house types of moradabad district, uttar pradesh. the measurementshave been carried out in residential buildings at a height of 2 m from the sea level,using a twin chamber radon dosimeter. the value of radon concentration in thepresent study varies between 10.5 bq/m3 and 29.5 bq/m3 with an average of 19.8bq/m3 while that of thoron is between 5.6 bq/m3 and 24 bq/m3 with an average of14.9 bq/m3 respectively. results, obtained with twin cup radon/thoron dosimeter,show that the concentration of indoor radon and thoron have been within therecommended level, with all the values staying under the safe limits, decreed bythe international commission on radiological protection (icrp) and unitednations scientific committee on the effect of atomic radiation (unscear).