see also:

• Ionising radiation
• https://www.theiet.org/media/9587/electromagnetic-fields-and-health.pdf
• https://www.arpansa.gov.au/sites/default/files/legacy/pubs/rps/rps3_hocking.pdf

• electromagnetic waves such as radio waves and light waves have an electrical wave and a magnetic wave at right angles to it and thus sources can give off both an electric field and a magnetic field
• electric and magnetic fields occur naturally and also come from human-made sources and are made whenever electricity is used
• this page is for EMF associated with extremely low-frequency (ELF) radiation from power supplies, etc and radio frequency EMF, it does not include light, UV, X-rays or gamma rays (see Ionising radiation for the latter two
• at usual exposures, the evidence would suggest they do little harm, nevertheless, many advocate for minimal exposure targets where possible, especially where children live such as in houses, schools and playgrounds as there have been suggestions prolonged exposures to magnetic fields higher than 0.4µT may double the risk of childhood leukaemia
• health concerns are for two quite separate non-ionising frequency bands:
  • 50/60Hz AC currents which produce ELF
  • 0.4-5GHz radio wave frequencies such as WiFi, mobile phones
• Australia has strict controls on the use of radio equipment as well as power equipment and power supply lines aimed to minimise adverse effects
  • eg. unlicensed users are restricted to 5W CB 2-way radios, while foundation licensed users can use up to 10W, unlicensed users are NOT permitted to transmitted on any other bands (apart from usual devices such as WiFi Routers, mobile phones, Bluetooth, low energy approved devices), and only those with ham radio licenses can transmit on the amateur radio bands
  • eg. all devices capable of transmitting radio must be approved and certified

• electromagnetic wave intensity in air is usually given as W/m²
  • all electromagnetic waves including radio waves and light obey the inverse square rule whereby the intensity falls to a quarter each time the distance from the source is doubled
• electric fields are usually given as V/m or kV/m
• magnetic fields are usually given as µT, mG (1mG = 0.1µT) or A/m (1 A/m = 0.5µT)
• Specific Absorption Rate (SAR) by the body are usually given as W/kg

• occupational for workers using electrical equipment: 10kV/m and for magnetic fields, 500 µT
  • exposure to frequencies between 10 MHz and 10 GHz, the limit for average power absorbed by the whole body is 0.4 W/kg, while the maximum SAR for the head and torso is 10 W/kg and the maximum SAR for the limbs is 20 W/kg ¹⁾
  • at a frequency of 900 MHz, field levels of up to 4.5 W/m² satisfy this requirement, while at 1.8 GHz, field levels of up to 9.0 W/m² fall within the limit²⁾
• general public (eg. power transmission lines): 5kV/m and for magnetic fields is 200 µT or 2000 mG
  • exposure to frequencies between 10 MHz and 10 GHz, the average power absorbed by the whole body should not exceed an SAR of 0.08 W/kg. The maximum SAR for the head and torso is 2.0 W/kg, while for the limbs it is 4.0 W/kg. ³⁾
• houses, schools and playgrounds: 10V/m and magnetic fields below 0.05µT
• an individual’s highest exposure is typically from any mobile device used in close proximity to the body and typically produce maximum absorbed powers (SAR) in the area of the body they touch, for example the head or limbs.

• most houses have background magnetic fields of 0.01-0.2µT however, this can be much higher if very close to high output mains sources can reach 1000 µT and 200V/m
  • a charging smartphone can produce 1kV/m within a cm but this rapidly dissipates to low levels by 30cm
• high-voltage overhead power lines - up to 10 kV/m and 100 µT
• small cell 5G mobile phone base stations produce weaker fields than 3G and 4G masts
• IoT devices will usually produce weaker EMFs than other appliances and systems, because they only transmit information periodically and in small amounts
• WLAN routers have very low power signals, typically 0.1 W
• potential very high exposures:
  • faulty microwave ovens
  • commercial radio transmission towers
    • touching a tower whilst it is on and you are grounded can cause very severe burns
    • usually have fences to warn people but youth may not heed this
    • even if turned off, they can cause a large static electric shock from nearby transmitters which may cause someone climbing it to fall
  • intense RF fields used in medical Rx may cause issues
  • intense beams of 60GHz radiofrequency which cause heating and pain have been developed as a means of crowd control by the military

• at 10–100 mV/m, low-frequency (20 Hz) electric and magnetic fields are able to interact with synapses in the retina to cause a flickering light sensation called electrophosphenes or magnetophophenes respectively
• above 6 V/m it causes small currents to flow in the peripheral nervous system
• above 10 V/m it causes small currents to flow in the central nervous system
• cardiac tissue is excitable at relatively high exposure levels (12.0 V/m peak)
• above 2 kV/m to 5 kV/m it can also cause non-lethal static electricity micro-shocks when a metal object is touched - much as walking across nylon carpet does
• burns may occur with very high levels of exposure
• myelinated nerves are thicker and more sensitive to EMF than unmyelinated nerves as in the grey matter of the CNS⁴⁾
• people with epilepsy may be more sensitive to 50/60Hz EMF than others
• long term exposures to magnetic fields above 0.3-0.4µT have been associated with a doubling of the risk of childhood leukaemia although the evidence is limited and causation seems unlikely

• medical implants such as orthopaedic rods as well as some costume jewellery may act as an antenna to concentrate an RF field esp. at < 100kHz
• high levels of electromagnetic interference of medical devices can be an issue eg. cardiac pacemakers, implantable defibrillators
• high levels can induce currents in the body, although nerve stimulation is unlikely at frequencies above 10 MHz
• at higher frequencies, EMFs can generate heat in the body, causing body temperature to rise
  • exposure to fields that generate temperature rises of more than 1-2 ºC can overwhelm the body’s thermoregulatory capacity and can cause tissue damage
    • hence the limit of whole-body exposure to a maximum SAR of 0.08 W/kg
    • for perspective though this heating is similar to that caused by moderate exercise such as a brisk walk or taking a warm bath
    • as frequency increases, EMF exposure of the body and the resultant heating becomes more superficial
      • above 6GHz, exposure is mainly on the skin and the heat is more easily dispersed into the environment
• much debate as been had on the potential adverse effects of mobile phones frequently held near the head to cause intracranial tumours however there is no sound evidence to support this ⁵⁾
• there is no good evidence to implicate neurobehavioural adverse effects at usual exposures
• very high levels sufficient to cause local heating effects may cause:
  • heating of muscles and potential for compartment syndrome
  • burns
  • keratitis and iritis
  • thermally hazardous levels may cause slow onset cataracts taking weeks after a high exposure event
  • headaches, lethargy and cognitive effects such as decreased concentration
  • prolonged dysasthesiae / paraesthesiae
  • delayed, persistent hypertension via autonomic system exposure
  • transient male infertility due to over-heating of testes
  • potential adverse fetal effects including risk of miscarriage (MHz frequencies in early pregnancy, GHz in later pregnancy)