Non-ionizing radiation

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Different types of electromagnetic radiation.
Different types of electromagnetic radiation.

Non-ionizing radiation (or, esp. in British English, non-ionising radiation) refers to any type of electromagnetic radiation that does not carry enough energy per quantum to ionize atoms or molecules — that is, to completely remove an electron from an atom or molecule.[1] Instead of producing charged ions when passing through matter, the electromagnetic radiation has sufficient energy only for excitation, the movement of an electron to a higher energy state. Nevertheless, different biological effects are observed for different types of non-ionizing radiation.[2][3]

Near ultraviolet, visible light, infrared, microwave, radio waves, low frequency RF and static fields are all examples of non-ionizing radiation. Visible and near ultraviolet may induce photochemical reactions, ionize some molecules or accelerate radical reactions, such as photochemical aging of varnishes[4] or the breakdown of flavoring compounds in beer to produce the 'lightstruck flavor'.[5] The light from the Sun that reaches the earth is largely composed of non-ionizing radiation, with the notable exception of some ultraviolet rays. However, most ionizing radiation is filtered out by the atmosphere (see Earth's atmosphere). Static fields do not radiate.[3]

[2] Source Wavelength Frequency Biological Effects
UVC Germicidal light 100 nm - 280 nm 1075 THz - 3000 THz Skin – Erythema, inc. pigmentation; Eye – Photokeratitis (inflammation of cornea)
UVB Tanning booth 280 nm - 315 nm 950 THz - 1075 THz Eye – Photokeratitis (inflammation of cornea) Skin – Erythema, inc. pigmentation Skin cancer, Photosensitive skin reactions, Production of vitamin D
UVA Black light, sunlight 315 nm - 400 nm 750 THz - 950 THz Eye – Photochemical cataract Skin – Erythema, inc. pigmentation
Visible Light lasers, sunlight, fire, LEDs, Light Bulbs 400 nm - 780 nm 385 THz - 750 THz Skin photo-ageing, Skin cancer; Eye – Photochemical & thermal retinal injury
IR-A lasers, remote controls 780 nm - 1.4 µm 215 THz - 385 THz Eye – Thermal retinal injury, thermal cataract; Skin burn
IR-B lasers, long-distance telecommunications 1.4 µm - 3 µm 100 THz - 215 THz Eye – Corneal burn, cataract; Skin burn
IR-C Far-infrared laser 3 µm - 1 mm 300 GHz - 100 THz Eye – Corneal burn, cataract; Heating of body surface
Microwave PCS phones, some mobile/cell phones, microwave ovens, cordless phones, motion detectors, radar, Wi-Fi 1 mm - 33 cm 1 GHz - 300 GHz Heating of body surface
Radio Frequency Radiation Mobile/Cell phones, television, FM, AM, Shortwave, CB, cordless phones 33 cm - 3 km 100 kHz - 1 GHz Heating with ‘penetration depth’ of 10 mm, Raised body temperature
Low frequency RF power lines > 3 km < 100 kHz Cumulation of charge on body surface Disturbance of nerve & muscle responses
Static Field[3] strong magnets, MRI infinite 0 Hz Magnetic - vertigo/nausea, Electric - charge on body surface

[edit] Ultraviolet radiation

Ultraviolet light can cause burns to skin[6] and cataracts to the eyes.[6] Ultraviolet is classified into near, medium and far UV according to energy, where near ultraviolet is non-ionizing. Ultraviolet light produces free radicals that induce cellular damage, which can be carcinogenic. Ultraviolet light also induces melanin production from melanocyte cells to cause sun tanning of skin. Vitamin D is produced on the skin by a radical reaction initiated by UV radiation.

Plastic sunglasses (polycarbonate) generally absorb UV radiation. UV overexposure to the eyes causes snow blindness, which is a risk particularly on the sea or when there is snow on the ground.

[edit] Visible and infrared, lasers

Visible light causes few effects to the human body. Bright visible light irritates the eyes. Visible-light lasers have much more powerful effects and may damage the eyes even at small powers. Very strong visible light is used for cauterizing hair follicles.

[edit] Microwave and radio frequency radiation

  • Biological effects
  • Effects on the Skin
  • Effects on the Eyes
  • Other Hazards
  • Occupational Exposure Standards

[edit] Low frequency ELF

  • Biological effects
  • Effects on the Skin
  • Effects on the Eyes
  • Other Hazards
  • Occupational Exposure Standards

[edit] Static fields

  • Biological effects
  • Effects on the Skin
  • Effects on the Eyes
  • Other Hazards
cf. Electric Power Transmission.
  • Occupational Exposure Standards

[edit] See also

[edit] References

  1. ^ Ionizing & Non-Ionizing Radiation.
  2. ^ a b Kwan-Hoong Ng (20th – 22nd October 2003). "[http://www.who.int/peh-emf/meetings/archive/en/keynote3ng.pdf Non-Ionizing Radiations – Sources, Biological Effects, Emissions and Exposures]". 
  3. ^ a b c John E. Moulder. Static Electric and Magnetic Fields and Human Health.
  4. ^ Helv. Chim. Acta vol. 83 (2000), pp. 1766. [1]
  5. ^ Photochem. Photobiol. Sci., 2004, 3, 337 - 340, DOI: 10.1039/b316210a [2]
  6. ^ a b UW EH&S Hazards of Ultraviolet Light.