A sampling method for occupational hazard surveillance of worker exposure to extremely low frequency (ELF) electromagnetic fields (EMF) in nonutility industries.
American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas. Fairfax, VA: American Industrial Hygiene Association, 1997 May; :72
A method was developed to determine the range of potential exposures to ELF magnetic fields in nonutility industries. Industries were selected based on their annual electric power consumption in accordance with the hypothesis that large power consumers would have elevated ambient magnetic fields. A total of 62 industrial facilities within thirteen 2-digit Standard Industrial Classification (SIC) codes participated in the study. Walk-through surveys were conducted with an EMDEX-U magnetic field meter and a MultiWave System II instrument. No correlation existed between electric power consumption and the geometric mean (GM) field magnitudes, which ranged from 0.4 to 16.1 mG. Chemicals and Allied Products (SIC 28) and Primary Metal Products (SIC 33) had the highest GMs. Specific source magnitudes were also highly variable across and within the sampled facilities, where maximum values ranged from 10 to 5300 mG. Data collected with the MultiWave indicated that some sources exhibited nonsinusoidal waveform patterns and frequency harmonics. Difficulty in establishing statistically significant associations between GMs across industries was expected because this study was designed to be range finding, and because of the high variability of field magnitudes and the small number of replicates. However, the lack of correlation between power consumption and ambient magnetic field magnitudes was surprising, and suggests that other surrogates for potential high exposure (such as source density) are needed. Industry classification was a poor tool for identifying facilities with high ambient magnetic fields, due to the wide variation in industrial processes and source types. Overall, 89% of the facilities had GMs at or below 4 mG, indicating that most facilities are probably within this range. However, facilities with GM field magnitudes above the 4 mG level may represent those with work areas with elevated magnetic fields and are likely candidates for personal monitoring and improved source characterization.
Magnetic-fields; Electromagnetic-fields; Industrial-environment; Electric-properties; Electrical-fields; Exposure-levels
American Industrial Hygiene Conference and Exposition, May 19-23, 1997, Dallas, Texas