Dynamics of Thoron Concentration in Dwellings of the Industrial Sites in Kannur District, Kerala

Abstract

The current study deals with the evaluation of the indoor concentration of 220Rn (thoron) in different dwellings with various construction materials used for the roof and floor in the major industrial sites of Kannur district, Kerala. A pinhole-based dosimeter coupled with LR-115 Solid State Nuclear Track Detector (SSNTD) and Direct Thoron Progeny Sensor (DTPS) were respectively used for the measurement of indoor concentration and equilibrium equivalent concentration of thoron. The thoron concentrations were found to vary from 124.64 Bqm-3 - 453.65 Bqm-3. The annual effective doses and excess lifetime cancer risks were observed in the range of 3.144 mSvy-1 -11.4 mSvy-1 and 13x10-3 to 45x10-3 respectively, and both exceeded the world average values recommended by UNSCEAR 2000. The study shows that, the houses with marble floor and concrete roof have comparatively higher values of thoron concentration, which indicates the significant contribution of construction materials to the enhanced radiation levels inside the dwellings.