In the International Telecommunication Union (ITU) radio-band convention, extremely low frequency (ELF) means 3–30 hertz (Hz). Other organizations use “ELF” for wider ranges when discussing electric and magnetic fields in workplace or health contexts, so the range depends on what the source is describing.
What does ELF mean?
ELF stands for extremely low frequency, a label for low-frequency electromagnetic phenomena. Frequency is measured in hertz: 1 Hz is one cycle per second. In the ITU radio-band designation shown in NASA’s radio-band table, ELF covers 3–30 Hz, corresponding to wavelengths of 100 million to 10 million metres. NASA notes that other approaches to naming frequency bands exist.
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Why do sources give different ELF ranges?
They are using the term for different purposes. A radio-band classification is not interchangeable with the frequency scope chosen for occupational guidance or a health assessment.
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstall| Context | Range | What the range describes |
|---|---|---|
| ITU radio-band designation, as presented by NASA | 3–30 Hz | A radio-frequency band label. |
| U.S. Occupational Safety and Health Administration (OSHA) | 1–300 Hz | ELF fields and related non-ionizing electromagnetic radiation in a workplace overview. OSHA’s overview page was checked in 2026: OSHA overview. |
| Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) | 0–100 kHz | A broad ELF electric- and magnetic-field context, described in ARPANSA’s ELF explainer; page checked in 2026. |
| World Health Organization (WHO) | Greater than 0 to 100,000 Hz (100 kHz) | The scope of its 2007 assessment of ELF electric and magnetic fields, not a substitute for the ITU radio-band definition: WHO Environmental Health Criteria 238. |
These figures are not competing measurements of one universal boundary. When a source gives a wider range, check whether it is discussing field exposure or a health-assessment scope rather than naming a radio band.
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Where do ELF fields come from, and how are they measured?
Power lines, electrical wiring, and electrical equipment produce power-frequency fields. The frequency depends on the electricity system: ARPANSA cites 50 Hz in Australia and 60 Hz in some other countries. Natural sources include atmospheric processes such as ionospheric currents, thunderstorms, and lightning, though artificial sources are the dominant sources in ordinary exposure contexts, according to ARPANSA.
Electric and magnetic fields are related but distinct. ARPANSA explains: “The electric field is produced by the voltage whereas the magnetic field is produced by the current.” Electric-field strength is measured in volts per metre (V/m). Magnetic flux density is commonly given in tesla or microtesla (T or μT), and sometimes gauss. Actual field levels vary with the source, distance, and configuration, so a frequency definition alone does not tell you the strength of an exposure. See ARPANSA’s field explanation.
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Is ELF radiation dangerous?
ELF is non-ionizing: it does not have enough energy to ionize atoms. That label does not mean every exposure level has no biological effect. ARPANSA says acute exposure to high ELF levels can affect nervous-system function, while such exposures are extremely rare outside medical and specialized occupational settings.
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1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsFor long-term effects, ARPANSA reports no established evidence linking ELF electromagnetic fields to long-term health effects. It describes an epidemiological association between prolonged exposure to higher-than-normal magnetic fields and childhood leukaemia, but says the evidence has methodological limitations and lacks support from laboratory or animal studies. An association is not proof that the fields cause the disease. WHO’s 2007 assessment covered fields from greater than 0 to 100 kHz; that scope alone does not imply that all frequencies in it carry the same risk. Sources: ARPANSA health information and WHO assessment.
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What is the simplest accurate definition?
For the ITU radio-band designation, ELF is 3–30 Hz. In workplace and health material, “ELF” may instead refer to a broader range of electric and magnetic fields. State the context whenever you give the number.
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