Assessment of natural radioactivity levels and associated dose rates in soil samples from historical city Panipat, India

The natural radioactivity levels have been determined by means of gamma ray spectroscopy in surface soil samples collected from the historical city Panipat and its surrounding areas. The activity concentrations are estimated for 238U (range from 14.82 ± 0.26 to 42.82 ± 0.84 Bq/kg), 232Th (from 12.94 ± 0.32 to 43.48 ± 0.96 Bq/kg) and 40K (from 238.05 ± 0.28 to 348.50 ± 0.95 Bq/kg). Radium equivalent activities are calculated to be in the range of 82.24-108.49 Bq/kg with an average value of 92.21 Bq/kg. Absorbed dose rates in air outdoors are measured in the range of 32.01-56.47 nGy/h with an average value of 44.16 nGy/h. The corresponding effective dose rates (indoor and outdoor) are calculated to be in the range of 0.09-0.158 mSv/y and 0.039-0.069 mSv/y respectively. The internal and external hazard index varies from 0.234 to 0.339 and 0.207 to 0.286 respectively. The activities of radium equivalent in all the soil samples are lesser than the limit (370 Bq/kg) recommended in the Organization for Economic Cooperation and Development (OECD) report and the annual effective dose was within the safe limit of 1 mSv/y.