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.

摘要

在这项研究中，通过配备 Geiger-Muller 管的手持式辐射测量仪，对埃努古市区 146 个室外地点的背景伽马辐射吸收剂量率进行了现场测量。为了评估研究环境的放射健康状况，根据测量的剂量率估计年有效剂量 (AED) 和超额终生癌症风险 (ELCR)。跨位置测量的辐射剂量率范围为 77.21 至 180.53 nGy h ^-1，平均值为 124.92 ± 2.00 nGy h ^-1。AED 和 ELCR 值范围为 0.09 至 0.22 mSv y ^-1，总体平均值为 0.15 mSv y ^-1和 0.33 × 10 ^-3至 0.77 × 10 ^-3总体平均值分别为 0.54 × 10 ^-3。测得的剂量率明显高于室外环境中 59 nGy h ^{-1的世界平均伽马辐射剂量。}剂量率显示背景辐射水平升高，表明环境受到辐射污染。ELCR 值表明，低水平辐射剂量在一生中的累积会引发埃努古城市地区居民的癌症发展。