An investigation of factors influencing indoor radon concentrations in dwellings of Northern Rajasthan, India

Abstract

An effort has been made to find possible relationships of indoor radon levels with building construction materials, ventilation condition of dwellings and soil gas radon levels. Indoor radon measurements were made using LR-115 type II cellulose nitrate films and the concentrations were estimated by knowing the track density of films through optical microscope. Soil gas radon levels were measured using RAD7, an electronic radon detector manufactured by Durridge Company, USA. This study sheds light on the seasonal indoor radon activities in Rajasthan dwellings. Maximum values of the indoor radon concentration were observed during the winter and minimum during the summer season. Results show that ventilation rate is inversely proportional to radon level. Highest level of indoor radon concentration was found in the mud type dwellings compared with dwellings made of concrete, cement and marble. A positive correlation (R2 = 0.45) between indoor radon and soil gas radon concentration was observed. A weak positive correlation (R2 = 0.22) was observed between soil gas radon concentration and radium content in soil. Indoor radon concentration was found to be associated with the presence of radon concentration in local soil, building material used for roof, floor and walls, type of ventilation conditions and presence of cracks on the walls/floor. Positive correlation between indoor and soil gas radon concentration suggest the large contribution of local soil towards indoor radon.