Radon Levels in Dwellings of Some Indian Cities

Abstract

Radiological importance of radon among other naturally occurring radionuclides is due to the fact that it is a noble gas in the uranium decay series with a fairly long half-life of 3.7 days. Being an inert gas it can easily disperse into the atmosphere as soon as it is released. The solid alpha active decay products of radon (²¹⁸P_o, ²¹⁴P_o) become airborne and attach themselves to the dust particles, aerosols and water droplets in the atmosphere. When inhaled, these solid decay products along with air may get deposited in the trachea-bronchial and pulmonary region of lungs resulting in the continuous irradiation of the cells, which may cause lung cancer. Measurement of time integrated concentration of indoor radon and its progeny are important as these are responsible for a major part of natural radiation dose to human beings and may be responsible for lung cancer. LR-115 Type II solid-state nuclear track detectors have been used to estimate the radon concentration in dwellings in various cities from different states of India. Annual effective dose has been calculated from the radon concentration to carry out the assessment of the variability of expected radon exposure of the population due to radon and its progeny. The radon levels in the dwellings vary from 64.8 to 222.1 Bq.m^-3 whereas annual effective dose vary from 2.5 to 7.5 m Sv. Radon concentration in Panmana (Kerala), the so called high back ground area is about two times more than the normal back ground area.