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정은교 ( Eun Kyo Chung ),김갑배 ( Kab Bae Kim ),정광재 ( Kwang Jae Chung ),이인섭 ( In Seop Lee ),유기호 ( Ki Ho You ),박정선 ( Jung Sun Park ) 한국산업위생학회 2012 한국산업보건학회지 Vol.22 No.1
Objectives: To compare the exposure level of extremely low frequency (ELF) magnetic fields among semiconductor workers, shipyard welders and office workers. Methods: To measure the ELF magnetic field concentration, EMDEX LITE (Enertech, USA) were used and monitored for eight hours continuously. Five companies handling the electric and magnetic field (EMF) source were investigated, which the exposure groups were classified into three groups: semiconductor workers, welders, and office workers. Welder group was chosen as a high exposed group and office group as a low exposed group. Results: The arithmetic mean (± SD) and geometric mean (GSD) of personal exposure level of semiconductor workers were 0.73 (± 1.33) μT, 0.43 (2.88) μT, respectively. The ceiling value ranged between 0.18 and 123.2 μT. Welders were exposed high with the arithmetic mean value of 3.46 (± 13.46) μT and geometric mean value of 0.45 (4.70) μT, respectively, and ceiling value range of 75.5~129.6 μT. The exposure levels of office workers were low compared to other exposed groups; the arithmetic mean 0.05 (± 0.13) μT, geometric mean 0.03 (2.38) μT and ceiling value range 0.37~3.35 μT. This study revealed statistically significant differences of the mean ELF magnetic field exposure doses among three groups (p < 0.01). Conclusions: The average ELF magnetic field exposure doses of semiconductor workers were much higher than those of office workers in control group, but were lower than those of welders in high exposure group.
정은교 ( Eun Kyo Chung ),유계묵,신정아 ( Jung Ah Shin ),권지운 ( Ji Woon Kwon ),박현희 ( Hyun Hee Park ),정광재 ( Kwang Jae Chung ),이인섭 ( Seop In Lee ),강성규 ( Seong Kyu Kang ),류향우 ( Hyang Woo Ryu ),김영선 ( Yong Sun Kim ) 한국산업위생학회 2010 한국산업보건학회지 Vol.20 No.3
This study was conducted to investigate the benzene exposure levels in coal chemical and petrochemical refining industries during BTX turnaround (TA) processes where benzene was being produced. Three companies producing benzene were selected, one coal chemical and two petrochemical industries. TA processes were classified into three stages: shut down, maintenance, and start up. Data was analyzed by classifying the refining method into 2 groups (Petrochemistry, Coal chemistry) for 823 workers. Comparing the data from petrochemical industries with data from a coal chemical refining industry, while benzene concentration levels of long-term samples during TA were not statistically different (p>0.05), those levels of short-term samples were significantly different (p<0.001). About 4.79 % of data in petrochemical industries exceed the occupational exposure limits (OELs) of benzene, 1 ppm. In a coal refining methods, about 15.7% exceeded the benzene OELs. The benzene concentrations in maintenance and start up stage of TA for petrochemical refineries were higher than those in a coal chemical refinery (p<0.01). These findings suggest that the coal chemical refining site requires more stringent work practice controls compare to petrochemical refining sites during TA processes. Personal protective equipments including organic respirators should be used by TA workers to protect them from benzene over-exposure.