Tag Archives: Outdoor

Gamma Dose Rate, Annual Effective Dose and Collective Effective Dose of Food Crop Producing Region of Ondo State, Nigeria (Published)

The activity concentrations of natural gamma-emitting radionuclides 238U, 232Th and 40K in soils from 7 sampling sites in Ondo State, southwestern Nigeria have been measured by using a well calibrated high resolution gamma ray spectrometer. The mean activity concentration values of 39.24±1.12, 52.86±1.40 and 445.02±12.24 Bq kg-1 for 238U, 232Th and 40K respectively were obtained for the State. Absorbed dose rates in outdoor air were calculated to be in the range of 12.35±0.65 and 179.59±4.1 nGy h-1 with an overall mean value of 67.50±1.86 nGy h-1. The corresponding outdoor annual effective dose rates were estimated to be between 22.7 and 330.6 μSv y-1 for the area assuming 30% occupancy factors. The average outdoor annual effective dose rate for most of the towns is 64882.95 μSv y-1 representing 92.65% of the world average value (70000 μSv y-1) given by UNSCEAR. The value of the collective effective dose as calculated from the outdoor annual effective dose rates was found to be 540858 person-Sv

Keywords: Dose, Gamma, Outdoor, Radiation, Radionuclide