DefinePK

Abstract

Gamma radiation level due to primeval radionuclides in surface soil in some South-Western cities in Nigeria has been carried out using a 7.6x7.6 cm NaI (Tl) detector. The mean absorbed dose rate and annual effective dose were evaluated from the measurement of 40K; 238U; 232Th. The absorbed dose rates values ranged from 18.6 to 68.4 with a mean (±SD) value of 44.2±15.9 nGy h-1 in Lagos area; 26.8 to 145.6 with a mean value of 72.9±35.6 nGy h-1 in Ibadan area and 30.9 to 98.9 with a mean value of 64.2±26.5 nGy h-1 in Akure area. The mean effective dose for these locations is 56.5, 93.3 and 82.2 μSv year-1, respectively. The mean value for the region is 0.8 mSv year-1, which is less than the 1 mSv year-1 recommended for normal environment by UNSCEAR.