In-situ assessment of background gamma radiation dose levels in outdoor environment of Enugu urban areas, Enugu state, Nigeria

Abstract

In this study, in-situ measurements of absorbed dose rates of background gamma radiation in 146 outdoor locations within Enugu urban areas were carried out by means of a hand held radiation survey meter equipped with Geiger-Muller tube. In order to assess the radiological health status of the studied environment, annual effective dose (AED) and excess lifetime cancer risk (ELCR) were estimated from the measured dose rates. The measured radiation dose rates across the locations ranged from 77.21 to 180.53 nGy h−1 with a mean value of 124.92 ± 2.00 nGy h−1. The AED and ELCR values ranged from 0.09 to 0.22 mSv y−1 with overall mean of 0.15 mSv y−1 and 0.33 × 10−3 to 0.77 × 10−3 with overall mean of 0.54 × 10−3, respectively. The measured dose rates were significantly higher than world average gamma radiation dose of 59 nGy h−1 for outdoor environment. The dose rates revealed an elevated background radiation levels signifying a radiation contaminated environment. The ELCR values indicate that the accumulation of low-level radiation doses over a lifetime exposure can initiate cancer development in residents of Enugu urban areas.