RESUMEN
Indoor radon, thoron and their progeny levels were measured in various types of dwellings during 2016-17 in Hemavathi river basin, Karnataka by using solid state nuclear track detector based pin-hole dosemeters; dwellings of various types were chosen for the measurement. The dosemeters containing the detector (LR-115, Type II Film) was used for this purpose. The concentration of indoor radon in the study area varied from 30.72 to 196.08 Bq m-3 with a median of 83.13 Bq m-3 and thoron concentration varied from 15.56 to 227.78 Bq m-3. Higher concentrations of radon and its progeny were observed in granite flooring and cement roofing dwellings compared to other types of dwellings. The reason for higher concentration of indoor radon and its progeny is due to activity of radium present in granite and provision of less ventilation in dwellings. The equilibrium equivalent radon, thoron concentrations and annual effective dose are discussed.