Study of indoor radon levels in Garhwal Himalayas using solid state nuclear track detector

The measurements of radon in indoor and outdoor environment by using LR-115 type II, plastic track detector in bare mode have been carried out in four districts (Tehri, Pauri, Utterkashi and Dehradun) of Garhwal Himalaya. One year data has been obtained from each house which is distributed in four quarters viz. Winter, Summer, Rainy and Autumn. About 350 houses have been surveyed and the radon levels were found to vary from 25 to 395 Bq/m(3). The annual average radon values were found to vary from 59 Bq/m(3) to 303 Bq/m(3). The indoor radon concentration was found to vary with seasonal variation, building material and mode of the construction of house. The winter/summer ratios for different type of houses vary substantially among different places. The radon concentration was found higher in mud houses due to the typical houses construction and building material used. More that 50% values of radon concentrations in mud houses are recorded above the ICRP recommended values and there is a specific need to measure the effect to the people living there. The results show that the building materials, mode of construction of house and the seasonal variations should be taken in account to calculate annual effective dose equivalent.