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目的通过开展工作场所工频电磁场测量的实验室间比对,分析职业卫生技术服务机构工频电磁场测量仪器测量结果的准确性及其影响因素。方法采用典型抽样方法,以广东省6家职业卫生技术服务机构的6台工频电磁场测量仪器为研究对象。以某变电站高压线为标准源,在其下方设置测量点作为比对现场进行工频电磁场的实验室间比对。采用配对t检验对标准源的稳定性进行评价,采用基于四分位数稳健统计技术的z比分数对测量结果进行分析。结果实验室间比对检测时和检测后标准源的电场强度、磁通密度分别比较,差异均无统计学意义[(555.03±2.94)vs(555.68±3.20)V/m,(2.30±0.06)vs(2.29±0.07)μT,P>0.05),可满足实验室间比对的稳定性方面的要求。2家参比机构的测量仪器未配备远程读数系统,由于需手持检测而存在邻近效应,导致工频电场测量数据偏高。其余4家参比机构配备远程读数系统的测量仪器实验室间z比分数(zB)为-0.52~1.10,实验室内z比分数(zW)为-1.28~0.37,|zB|和|zW|均小于2.00,结果均满意。6家参比机构工频磁场仪器zB为-0.67~1.26,zW为-0.59~0.90,|zB|和|zW|均小于2.00,结果亦均满意。结论以高压线为标准源进行工作场所工频电磁场测量仪器实验室间比对具有可行性。未配备远程读数系统的测量仪器不能用于工频电场的检测,但可用于工频磁场的检测。配备远程读数系统的测量仪器工频电场、磁场的比对结果均满意。
OBJECTIVE To analyze the accuracy and influencing factors of measurement results of power frequency electromagnetic field measuring instruments of occupational health service agencies by carrying out laboratory comparison of power frequency electromagnetic field measurements in the workplace. Methods A typical sampling method was used to study six commercial power frequency electromagnetic field measuring instruments of six occupational health service agencies in Guangdong Province. Taking a substation high voltage line as the standard source, a measuring point is set below it as an inter-laboratory comparison of on-site power frequency electromagnetic fields. The paired t-test was used to evaluate the stability of the standard source and the z-score based on quartile robust statistical techniques was used to analyze the measurement results. Results There was no significant difference in electric field strength and magnetic flux density between the standard test and the standard test (555.03 ± 2.94 vs 555.68 ± 3.20 vs 2.30 ± 0.06, vs (2.29 ± 0.07) μT, P> 0.05), which can meet the stability requirements of laboratory-to-laboratory comparison. 2 reference institutions measuring instruments are not equipped with remote reading system, due to the need for hand-held detection of the proximity effect, resulting in high frequency electric field measurement data. The z-scores (zB) of the measuring instruments with remote reading system in the other four reference institutions were -0.52 ~ 1.10, the z-scores in the laboratory were -1.28 ~ 0.37, | zB | and | zW | Less than 2.00, the results are satisfactory. 6 reference institutions power frequency magnetic field instrument zB -0.67 ~ 1.26, zW -0.59 ~ 0.90, | zB | and | zW | are less than 2.00, the results are also satisfactory. Conclusion It is feasible to use the high voltage line as the standard source for laboratory comparison of working frequency electromagnetic field measuring instruments in the workplace. Measuring instruments that are not equipped with a remote reading system can not be used for the detection of power frequency electric fields but can be used for the detection of power frequency magnetic fields. Measuring instruments equipped with remote reading system power frequency electric field, magnetic field comparison results are satisfied.