Baseline Studies of Terrestrial Outdoor Gamma Dose Rate Levels in Nigeria

TLDR: The average annual outdoor radiation exposure dose rate due to the radioactivity concentration of 40 K, 238 U and 232 Th in the soil across different environments in Nigeria have been carried out using the low-cost method of in situ γ ray spectrometry as discussed by the authors.

Abstract: The outdoor radiation exposure dose rates due to the radioactivity concentration of 40 K, 238 U and 232 Th in the soil across different environments in Nigeria have been carried out using the low-cost method of in situ γ ray spectrometry. Measurements were made in 18 cities, spread across the three major zones of the country. The radioactivity concentrations of these radionuclides in the soil were used to determine their radiation absorbed dose rates in the air. The range of average total dose rate due to the three radionuclides in the Eastern zone is between 0.025 and 0.081 μGy.h -1 with an average of 0.040 ± 0.006 μGy.h -1 , 0.041 and 0.214 μGy.h -1 with a mean of 0.089 ± 0.014 μGy.h -1 for the Western zone and between 0.066 and 0.222 μGy.h -1 with a mean of 0.102 ± 0.032 μGy.h -1 for the Northern zone. The average annual outdoor effective dose equivalents of 51 ± 8 μSv.y -1 114 ± 18 μSv.y -1 and 130 ± 41 μSv.y -1 have been estimated for the Eastern, Western and Northern zones, respectively. The average annual effective dose equivalent for the country has been estimated to be 98 ± 15 μSv.y -1 and the collective effective dose equivalent as 9.7 X 10 3 man.Sv.y -1 . Measurements have been taken as representing the baseline values of natural radioactivity as no artificial radionuclide was detected at any of the sites surveyed.