Okuno T, Jonai H, Kawakami T
National Institute of Industrial Health, Kawasaki, Japan.
Sangyo Igaku. 1991 Nov;33(6):491-500. doi: 10.1539/joh1959.33.491.
Exposure of workers to electric and magnetic fields from radiofrequency dielectric heaters (RF heaters) to process polyvinyl chloride material was surveyed. Measurements of electric and magnetic field strengths were made in 10 workers operating 7 RF heaters at 3 plants in Japan. Six of the RF heaters are of the sewing machine type and the other is of the shuttle tray type. In all the RF heaters surveyed the nominal frequency of the radiofrequency generator was 40 MHz, and therefore electric and magnetic field from these are assumed to oscillate at the same frequency. The power output ranged from 0.83 W to 1.8 W for the sewing machine type and was 2.4 W for this shuttle tray type. Measurements were made at about 5 cm from the surface of the hand, eye, chest, waist, knee and foot of each worker. The meter readings were converted to equivalent plane wave power density and corrected for duty cycle (0.073 to 0.27). It was found that all the workers surveyed were exposed to electric and magnetic field strengths greater than the TLV recommended by ACGIH (1 mW/cm2). For the hand, eye, chest, waist, knee and foot of the worker, 95%, 63%, 32%, 47% and 36% and 27% of the measured field strengths exceeded the TLV, respectively. Especially for the sewing machine type RF heaters, electric fields at the hand and eye were extremely strong. Thus, for the hand, 100%, 75% and 38% of the measured electric field strengths exceeded the TLV, ten times the TLV, and one hundred times the TLV, respectively, and for the eye, 88% and 25% exceeded the TLV and ten times the TLV, respectively. No correlation was observed between power output of the RF heaters and measured electric and magnetic field strengths at any anatomical site of the worker.
对在加工聚氯乙烯材料时接触射频介质加热器（RF加热器）产生的电场和磁场的工人进行了调查。在日本3家工厂操作7台RF加热器的10名工人中进行了电场和磁场强度测量。其中6台RF加热器是缝纫机类型，另一台是穿梭托盘类型。在所调查的所有RF加热器中，射频发生器的标称频率为40MHz，因此假定来自这些加热器的电场和磁场以相同频率振荡。缝纫机类型的功率输出范围为0.83W至1.8W，穿梭托盘类型的功率输出为2.4W。在距每名工人的手、眼、胸、腰、膝和脚表面约5cm处进行测量。将仪表读数转换为等效平面波功率密度，并根据占空比（0.073至0.27）进行校正。结果发现，所有接受调查的工人所接触的电场和磁场强度均高于美国政府工业卫生学家会议（ACGIH）建议的阈限值（1mW/cm²）。对于工人的手、眼、胸、腰、膝和脚，所测场强分别有95%、63%、32%、47%、36%和27%超过了阈限值。特别是对于缝纫机类型的RF加热器，手和眼处的电场极强。因此，对于手，所测电场强度分别有100%、75%和38%超过阈限值、阈限值的10倍和阈限值的100倍，对于眼，分别有88%和25%超过阈限值和阈限值的10倍。在RF加热器的功率输出与工人任何解剖部位所测电场和磁场强度之间未观察到相关性。
