Long-term monitoring of outdoor natural gamma absorbed dose rate in air in Bengaluru, Karnataka, India.

This article focuses on the long-term continuous measurement of natural outdoor gamma absorbed dose rate in air across Bengaluru, Karnataka, India, conducted from 2013 to 2023 as part of the Indian Environmental Radiation Monitoring Network program. Using 41 permanently installed Geiger-Mueller detector-based environmental radiation monitors (ERMs), the study found that the mean absorbed gamma dose rate ranged from 84 ± 9 to 156 ± 4 nGy·h⁻¹, with an overall mean of 124 ± 15 nGy·h⁻¹, corresponding to an estimated mean annual effective dose of 0.15 ± 0.02 mSv·y⁻¹. The variation in dose rates across locations is attributed to differences in primordial radionuclide concentrations in local soils and geology, primarily the Peninsular Gneissic Complex. Compared to Indian and global averages, Bengaluru exhibits higher background radiation levels, though these remain significantly lower than those in known high natural background radiation areas worldwide. The study provides valuable baseline data for radiation environment assessment and protection efforts in the region.