An Investigation of Indoor Terrestrial Gamma Radiation and Its Health Hazard in the Garhwal Foothills

This study assesses indoor gamma radiation from naturally occurring radioactive substances. It was carried out to measure the gamma radiation dose rate indoors in the Dehradun district. The Dehradun district is situated in the foothills of the Garhwal Himalaya. The study deals with the estimation of possible radiological health risk to the resident community from long-term exposure in enclosed areas. The ATOMTEX portable gamma survey meter was used to measure the gamma dose rate at 25 different locations. The level of indoor gamma dose rate ranges from 0.09 µSv/h to 0.21 µSv/h, with an average of 0.15 ± 0.02 µSv/h. The estimated values of Annual Effective Dose Equivalent in the context of indoor exposure were found to be between 0.44 and 1.03 mSv/y, with a mean of 0.78 mSv/y. The value is below the population-weighted average of 0.80 mSv/y for indoors, as reported by United Nations Scientific Committee on the Effects of Atomic Radiation. The increased levels of indoor radiation stem primarily from the natural radionuclides within local building materials, which include Uranium-238, Thorium-232, and Potassium-40 within the building materials. The Lifetime Effective Dose was between 28.69 mSv and 66.96 mSv, whereas the Excess Lifetime Cancer Risk of ranged from 1.43 × 10⁻³ to 3.34 × 10⁻³ with an average of 2.53 × 10⁻³ was found in more than an acceptable limit of 0.29 × 10⁻³. Such observations underscore the importance of systematic radiological follow-up, community education, and remedial interventions.