Study of radon exhalation in dwellings of Bangalore city, India

Radon is a noble radioactive gas; produced by the disintegration of radium isotopes which are decay products of uranium and thorium, respectively. After radon is generated from radium by decay process in the solid grains, they emanate to pore gases or fluids and then migrate a significant distance from the site of generation in rocks or soils near the earth's surface, finally enter the atmosphere before undergoing radioactive decay in an exhalation process. Lung cancer is the principal concern associated with radon exposure. Radon itself is not responsible for the hazard; primary concern is associated with the short-lived decay products of radon. These species are chemically reactive and so may be deposited on respiratory tract tissues when inhaled may damage cells near the deposition site, contributing to increase the risk of lung cancer. Therefore, the measurement of radon in the environment is important. In view of this an attempt has been made to study the radon exhalation in dwellings of Bangalore, India. Solid State Nuclear Track based CAN techniques were used for the measurements of radon exhalation. The preliminary results showed the large variations in the concentrations, the radon exhalation from the walls and floorings of the room varied from 90.3 to 113.5 mBqm-2h-1 with an arithmetic mean of 101.2 mBqm-2h-1 and 649.3 to 816.4 mBqm-2h-1 with an arithmetic mean of 727.7 mBqm-2h-1 respectively. Since radon and their progenies contribute with greater than 50% of radiation dose received from natural and manmade radiation sources, it is important to understand the generation process of radon from different materials, their migration from this material and finally their entering process into outdoor atmosphere and indoor to our houses and our working places. The details of experimental methods and the results are discussed in this paper. (author)