In the present investigation, newly designed pin hole based radon-thoron dosimeter with LR-115 track detectors has been used for the integrated determination of radon, thoron and their progeny levels in the indoor air of the dwellings of the Union Territory (U.T.) Chandigarh for checking the indoor air quality. The soil and the building materials are the major source of the indoor radon and the contribution of these towards indoor radon levels depends upon the radium content and exhalation rates and so can be used as a primary index for radon levels in the dwellings. Due to this the radon exhalation rate of some soil samples of the study area has been measured using active technique. The exhalation rate of the sand samples, utilized for the construction purpose, available from the study area has also been measured.
The concentration of indoor radon was varying from 24.2 ± 1.1 Bq m–3 to 62.1 ± 3.1 Bq m–3. The thoron concentration was found to be varying from 3.0 ± 0.1 Bq m–3 to 99.2 ± 4.9 Bq m–3. The annual inhalation dose received by the inhabitants of these dwellings is in the safe limits. A good positive correlation was found between indoor radon concentration and radon mass exhalation rate of the soil samples of the study area.