Department of Environmental Health, University of Johannesburg, Doornfontein Campus, Johannesburg, 2028, South Africa.
Department of Life Sciences, Central University of Technology, Bloemfontein, Free State, South Africa.
Environ Monit Assess. 2018 Aug 23;190(9):544. doi: 10.1007/s10661-018-6916-8.
The aim of this study was to evaluate the exposure levels of ELF magnetic fields in the residential areas of Mangaung metropolitan municipality. Fifteen residential sites were randomly selected in Bloemfontein, nine in Botshabelo and six in Thaba Nchu areas of Mangaung. Measurements were collected at the distances of 3 m, 6 m and 9 m outside electrical substations, near every corner, using a Trifield meter model XE 100. Measurements were also collected from four different corners inside substations, near barrier screening and were referred to as a distance of 0 m (reference point). The results indicated a non-significant difference among 15 residential areas; BRE1 to BRE15 and six areas; TNRE1 to TRNE6. The exposure levels were significantly high in one residential area BORE1 (0.55 μT) as compared to other residential sites in Botshabelo (p < 0.001). The results obtained from the measurements also show a significant difference between the residential areas BORE4 and BORE8 (p < 0.01) as well as BORE4 and BORE9 (p < 0.006). The four distance interims also demonstrated a highly significant difference (p < 0.0001) when compared to one another. The t test showed a statistically significant difference for exposure levels recorded at 3 m, 6 m and 9 m in comparison to 0 m (p < 0.01). The exposure levels recorded at 3 m were also significantly different to those recorded at 6 m (p < 0.05) and 9 m (p < 0.01). The exposure levels measured at all distances are below the ICNIRP guidelines and the fields decrease rapidly with an increased distance from the source.
这项研究的目的是评估马格旺大都会市住宅区的极低频磁场暴露水平。在布隆方丹随机选择了 15 个住宅地点，在博茨哈贝勒选择了 9 个，在塔巴讷楚选择了 6 个。使用 Trifield 仪表模型 XE 100 在距离变电站 3 米、6 米和 9 米的外部以及每个角落附近进行测量。还从变电站内四个不同角落、靠近屏蔽物进行了测量，称为 0 米（参考点）。结果表明，15 个住宅区之间，BRE1 到 BRE15 和六个住宅区，TNRE1 到 TRNE6 之间没有显著差异。博茨哈贝勒的一个住宅区 BORE1（0.55μT）的暴露水平明显高于其他住宅区（p<0.001）。测量结果还显示，博雷尔 4 号和 8 号（p<0.01）以及博雷尔 4 号和 9 号（p<0.006）之间存在显著差异。四个距离间隔之间也存在高度显著差异（p<0.0001）。t 检验显示，与 0 米相比，3 米、6 米和 9 米记录的暴露水平存在统计学显著差异（p<0.01）。与 6 米（p<0.05）和 9 米（p<0.01）相比，3 米记录的暴露水平也存在显著差异。所有距离测量的暴露水平均低于 ICNIRP 指南，并且随着与源距离的增加，场强迅速下降。
