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Non-ionizing 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]

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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

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.

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.

Microwave and radio frequency radiation

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

Low frequency ELF

Biological effects

Effects on the Skin
Effects on the Eyes
Other Hazards

Occupational Exposure Standards

Static fields

Biological effects

Effects on the Skin
Effects on the Eyes
Other Hazards

cf. Electric Power Transmission.

Occupational Exposure Standards

References

^ Ionizing & Non-Ionizing Radiation.
^ ^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]".
^ ^a ^b ^c John E. Moulder. Static Electric and Magnetic Fields and Human Health.
^ Helv. Chim. Acta vol. 83 (2000), pp. 1766. [1]
^ Photochem. Photobiol. Sci., 2004, 3, 337 - 340, DOI: 10.1039/b316210a [2]
^ ^a ^b UW EH&S Hazards of Ultraviolet Light.

Category: Radioactivity

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Non-ionizing_radiation". A list of authors is available in Wikipedia.