Monitoring of outdoor natural gamma absorbed dose rate in air in Hyderabad, Telangana, India.

This article focuses on the long-term monitoring of natural outdoor gamma absorbed dose rates in air across Hyderabad, Telangana, India, using the Indian Environmental Radiation Monitoring Network (IERMON), which employs Geiger–Mueller detector-based environmental radiation monitors (ERMs). The study, covering 59 locations within the city known for elevated natural background radiation due to granitic rocks rich in primordial radionuclides, found dose rates ranging from 104 to 258 nGy·h⁻¹ with a mean of 193 ± 40 nGy·h⁻¹, exceeding both Indian and global averages. The mean annual effective dose (AED) from outdoor gamma radiation was estimated at 0.24 ± 0.05 mSv·y⁻¹, with seasonal analysis showing the lowest dose rates during the monsoon season, attributed to reduced radon emanation. These findings provide baseline data for environmental radiation levels in Hyderabad and highlight spatial variability linked to local geology.