Natural radiation level in the environment of Tehri Garhwal, Uttaranchal

The natural radiation levels were measured in about 50 residential houses of Tehri Garhwal, Uttaranchal, using an environmental radiation dosimeter in both the indoor and the outdoor atmosphere. The total gamma ray activity was found to vary from 29.74 µR/h to 41.19 µR/h with a mean of 36.5 µR/h for the indoor environment, whereas for outdoors it varied from 28.76 µR/h to 43.46 µR/h with a mean of 30.1 µR/h. The resulting gamma ray dose at 20 traditional rural houses was also measured. The values varied from 38.91 µR/h to 77.68 µR/h with a mean of 66.6 µR/h. Measurements of the diurnal variation of the dose rates showed that they are higher in the rural traditional houses than in modern houses. The variations of dose rate with the type of building material, the mode of construction and the age of houses are also discussed.