Terrestrial gamma radiation dose (TGRD) rates and radiological risk assessments in Tiru region of the Naga Schuppen Belt, India

The aim of the present study is to assess the levels of dose rates and the potential risks of exposure to terrestrial gamma radiations in indoors and outdoors in houses in Tiru coal mining area. A highly sensitive portable micro-R gamma survey metre incorporated with a NaI (Tl) scintillator has been used for this study. Indoor and outdoor gamma dose rates (GDRs) have been estimated to be 58.5–178.3 nGy h⁻¹ and 55.5–81.9 nGy h⁻¹, respectively, with averages of 89.7 $\pm$ 7.4 nGy h⁻¹ and 65.7 $\pm$ 5.8 nGy h⁻¹, considerably higher than the reported global population-weighted averages. The annual effective doses (AEDs) for indoors and outdoors have been estimated to be in the ranges of 0.29–0.87 mSv y⁻¹ and 0.07–0.1 mSv y⁻¹, with averages of 0.44 $\pm$ 0.04 mSv y⁻¹ and 0.08 $\pm$ 0.01 mSv y⁻¹, which are marginally higher than the reported global averages. The excess lifetime cancer risk (ELCR) has been calculated and found to be in the range of 1.2 $\times$ 10⁻³-3.4 $\times$ 10⁻³ with an average of 1.8 $\times$ 10⁻³. This study contributes significantly to the scientific understanding of radiation exposure in an open-cast coal mining area as well as its potential impact on human health.