EMF Spot Measurements | |||
---|---|---|---|
The data summarized in this table came from various sources, all of which are listed in the References section. | |||
Industry and Sources | ELF magnetic fields measured in mG |
Comments | Other frequencies |
Mechanical equipment used in manufacturing | |||
Electric resistance heater | 6000 - 14,000 | Tool exposures measured at operator's chest |
VLF |
Induction heater | 10 - 460 | High VLF | |
Hand-held grinder | 3000 | ||
Grinder | 110 | ||
Lathe, drill press, etc. | 1 - 4 | ||
Electro-galvanizing | |||
Rectification room | 2000 - 4600 | Rectified DC current (with an ELF ripple) galvanizes metal parts |
High static fields |
Outdoor electric line and substation |
100 - 1700 | ||
Aluminum refining | |||
Aluminum pot rooms | 3.4 - 30 | Highly-rectified DC current (with an ELF ripple) refines aluminum |
Very high static field |
Rectification room | 300 - 3300 | High static field | |
Steel foundry | |||
Ladle refinery ladle electrodes active |
170 - 1300 | Highest ELF field was at the chair of control room operator |
High ULF from the ladle's big magnetic stirrer |
electrodes inactive | 0.6 - 3.7 | ||
Electro-galvanizing unit | 2 - 1100 | High VLF | |
Television broadcasting | |||
Video cameras (studio and minocam) |
7.2 - 24 | Measured 1 ft. away | VLF |
Vidio tape degaussers | 160 - 3300 | ||
Light control centers | 10 - 300 | Walk-through survery | |
Studio and newsrooms | 2 - 5 | ||
Telecommunications | |||
Relay switching racks | 1.5 - 32 | Measured 2 in. - 3 in. from relays | Static fields and ULF-ELF transients |
Switching rooms (relay & electronic switches |
0.1 - 1300 | Walk-through survey | Static fields and ULF-ELF transients |
Under ground phone vault | 3 - 5 | Walk-through survey | |
Hospitals | |||
Intensive care unit | 0.1 - 220 | Measured at nurse's chest | VLF |
Post-anesthesia care unit | 0.1 - 24 | VLF | |
Magnetic resonance imaging (MRI) |
0.5 - 280 | Measured at technician's work locations |
Very high static field, VLF and RF |
Government offices | |||
Desk work locations | 0.1 - 7 | Peaks due to laser printers | |
Desks near power center | 18 - 50 | ||
Power cables in floor | 15 - 170 | ||
Computer center | 0.4 - 6.6 | ||
Can opener | 3000 | Appliance fields measured 6 in. away |
|
Desktop cooling fan | 1000 | ||
Other office appliances | 10 - 200 | ||
Building power supplies | 25 - 1800 | ||
Information about the magnitude of other frequencies measured can be found in the original reports from which data for this table were drawn. They are listed in the References section. |