Regional survey of indoor gamma-radiation and estimation of radiation exposure indexes in and around Vellore district, Tamil Nadu

The ambient gamma (γ)-radiation levels were measured in various types of dwellings in and around Vellore district. The survey was performed by using a portable Micro-R Survey Meter NUCLEONIX in different types of dwellings. The background γ-radiation exposure inside the dwelling was obtained in a total of 632 dwellings located in 30 different geographical positions in Vellore and nearby places. From the measured dose values, the radiation exposure indexes were estimated such as absorbed dose rate (ADR) and annual effective dose (AED) for the population. The present study has taken an initiative to formulate the environmental γ-radiation reference level for indoor γ-radiation level in and around Vellore district, Tamil Nadu. The calculated highest mean AED was found in concrete dwellings at 0.58 ± 0.07 mSvy−1. The highest ADR was found to be 1219 μGy/yr in tiled house. Furthermore, the work was extended to find the correlation between the temperatures, time, and type of house with radiation for a day with 2 h of regular time interval in these four types of houses and analyzed with response surface methodology.