Assessment of terrestrial gamma radiations and radiological risks in Makum Coalfield, India

The present study reports the terrestrial gamma radiation exposures in dwellings in Makum Coalfield, India, using a Micro-R Gamma Survey Metre. The geometric means (GMs) of indoor and outdoor gamma dose rates were found to be 150.3 +/- 7.4 nGy h-1 and 129.2 +/- 6.6 nGy h-1, respectively, which are considerably higher than the global population-weighted average of 84 nGy h-1 and 59 nGy h-1, respectively. The estimated GMs of annual effective dose equivalents and excess lifetime cancer risks were also found to be substantially higher than the global recommended values of 0.48 mSv y-1 and 1.45 x 10-3, respectively.