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Evaluation of occupational exposure to EMF from walk-through metal detectors.

American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 1998 May; :37
Over the last several years the National Institute for Occupational Safety and Health (NIOSH) has received several requests to evaluate occupational exposure to electromagnetic fields (EMFs) generated by metal detectors used for various security purposes. In 1996 NIOSH evaluated 52 different walk-through arch-style and several handheld metal detectors at 35 United States courthouses located in 15 states. We found no other publications or reports that had measured the EMF exposure from these security devices. However, a few reports did address potential biological effects of walk-through detectors in individuals having pacemakers. Measurements of subradio-frequency magnetic fields, both extremely low frequency (ELF) and very low frequency (VLF), were made both inside the arch as well as outside and away from the surface of the arch. In addition, measurements were made at actual employee location to verify personal exposure levels. During the evaluation, both old and new model metal detectors were evaluated; however, most of the units evaluated were new (less than 5 years old) and all were in good operating conditions. On older models magnetic fields were produced on only one side of the arch, while on the newer units magnetic fields were generated on both sides. The metal detector systems measured in this evaluation are capable of producing fields up to about 50,000 Hz. Equipment used to measure these fields were the EMDEX II exposure system, Multiwave System II waveform capture instrument, Holiday Industries, Inc. Model HI- 3637 three-axis VLF magnetic field meter, and a Hewlett-Packard Model 3561A Digital Signal Analyzer with a special calibrated antenna. The maximum inside arch magnetic field level was 2736 milligauss (mG) in the ELF region and 600 mG in the VLF region, while outside the arch magnetic field levels were 2400 mG (ELF) and 1200 mG (VLF). The results of these measurements indicate that personnel who work in close proximity to these units, under normal operating conditions, are not exposed to magnetic field levels in the subradio- frequency regions in excess of occupational guidelines promulgated by the American Conference of Governmental Industrial Hygienists.
Electronic-devices; Electronic-equipment; Exposure-assessment; Exposure-levels; Exposure-limits; Electromagnetic-fields; Magnetic-fields; Metals; Detectors; Warning-devices; Signal-devices; Law-enforcement-workers; Measurement-equipment; Nonionizing-radiation
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American Industrial Hygiene Conference and Exposition, May 9-15, 1998, Atlanta, Georgia