In the ITU radio-band designation, extremely low frequency (ELF) means frequencies from 3 to 30 hertz (Hz). The label is context-dependent: workplace and health sources also use “ELF” for broader ranges of electric and magnetic fields, so the range should be read alongside the source’s purpose.
What does extremely low frequency mean?
Extremely low frequency, abbreviated ELF, is the name of a frequency band. NASA’s spectrum-band table, which attributes its designations to the International Telecommunication Union (ITU), places ELF at 3–30 Hz. NASA gives the corresponding wavelength range as 108 to 107 metres. These are classification values, not measurements of a particular exposure or device. NASA’s band-designator explanation notes that other systems for naming frequency bands also exist.
In that ITU-attributed table, the adjacent bands are super low frequency (SLF), 30–300 Hz, and ultra low frequency (ULF), 300 Hz–3 kHz. Those labels help locate ELF in a spectrum classification; they do not make every source using “ELF” use the same boundaries.
Why do some sources give a different ELF range?
Some occupational and health material is describing low-frequency electric and magnetic fields rather than defining the ITU radio band. The ranges therefore answer different questions and should not be treated as competing measurements of one universal boundary.
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| Source and context | Range used | How to interpret it |
|---|---|---|
| NASA, presenting the ITU radio-band designation | 3–30 Hz | The concise band definition for a spectrum question. NASA |
| U.S. Occupational Safety and Health Administration (OSHA), workplace ELF-field overview | 1–300 Hz | A workplace and field-safety usage, not the ITU band boundary. OSHA’s page was checked in 2026. OSHA |
| Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), ELF EMF explainer | 0–100 kHz | A broad electric- and magnetic-field context. The page was checked in 2026. ARPANSA |
| World Health Organization (WHO), Environmental Health Criteria 238 assessment | Greater than 0 to 100,000 Hz (100 kHz) | The scope of that health assessment, not a replacement for the ITU band table. The publication is from 2007. WHO |
When a source gives a different range, check whether it is discussing a named spectrum band, workplace fields, or the scope of a health assessment. In a general frequency-band answer, state the context explicitly: ELF is 3–30 Hz under the ITU radio-band designation shown by NASA.
Where do ELF fields come from, and how are they measured?
Power lines, electrical wiring, and electrical equipment produce power-frequency ELF fields. The relevant power frequency differs by country: ARPANSA identifies 50 Hz in Australia and 60 Hz in some other countries. It also describes natural sources associated with atmospheric processes, including ionospheric currents, thunderstorms, and lightning. The 50 Hz and 60 Hz examples describe power-system frequencies; they are not the boundaries of the ITU ELF band.
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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 reported in tesla or microtesla (T or μT), and sometimes gauss. Field strength varies with the source, distance, and configuration, so a number without those details does not describe a general ELF exposure. ARPANSA’s ELF field explainer
Is ELF radiation ionizing?
No. ELF fields are non-ionizing; they do not have the energy associated with ionizing radiation. Non-ionizing does not mean that every field strength is biologically inert. OSHA uses ELF for non-ionizing fields in its workplace overview and notes that power lines, wiring, and electrical equipment are sources in its 60 Hz examples. OSHA states that it has no specific standards addressing ELF fields; that statement concerns OSHA and should not be generalized to regulations in other jurisdictions. OSHA’s overview
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What is established about possible health effects?
ARPANSA says acute exposure to high ELF levels can affect nervous-system function, while noting that such high exposures are extremely rare outside medical and specialized occupational settings. For long-term effects, ARPANSA reports no established evidence linking ELF EMF to long-term health effects. It also describes an epidemiological association between prolonged exposure to higher-than-normal magnetic fields and childhood leukaemia, but says the evidence has methodological limitations and is not supported by laboratory or animal studies. An observed association is not proof that ELF exposure causes the disease. ARPANSA’s health-effects summary
WHO’s 2007 assessment covered ELF electric and magnetic fields from greater than 0 to 100 kHz. That describes the assessment’s scope; it does not mean that every frequency in that range has the same exposure profile or health implications. WHO Environmental Health Criteria 238
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