Mapping of the Distribution of Natural Gamma Radiation (NGR) Dose Rates in Mining Areas of Nassarawa Eggon, Nasarawa, North Central Nigeria

Natural background gamma radiation (NGR), primarily from terrestrial radionuclides uranium, thorium, and potassium, significantly contributes to human radiation exposure, with a global average effective dose of 2.4 mSv per year (UNSCEAR, 2000). Geological composition, particularly granitic rocks, influences higher NGR dose rates, necessitating localized studies to assess environmental and health impacts. This study investigates NGR levels in Nasarawa Eggon, Nasarawa State, Nigeria, an area with increasing mining activities and population growth. Using a certified Geiger-Müller counter, 150 in-situ measurements were conducted across Agidi, Akun, and Nasarawa Eggon development areas, with dose rates converted to nGy/h. The mean dose rate was 171.26 nGy/h, exceeding twice the global average of 59 nGy/h, with Agidi recording the highest (184.88 nGy/h). An isodose map, generated using QGIS and Kriging interpolation, illustrated NGR distribution. Calculated annual effective doses were 0.84 mSv (indoor) and 0.21 mSv (outdoor), below the ICRP’s 1 mSv limit but above Nigerian and global averages. These findings highlight elevated NGR levels linked to local geology and mining, underscoring the need for further radiological studies to identify contributing radionuclides and ensure public safety.