| 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. | |||