Non-ionizing radiation or
non-ionising radiation refers to any type of
electromagnetic radiationElectromagnetic radiation is a ubiquitous phenomenon that takes the form of self-propagating waves in a vacuum or in matter. It consists of electric and magnetic field components which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation...
that does not carry enough
energyIn physics, energy is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law...
per
quantumIn physics, a quantum is the minimum unit of any physical entity involved in an interaction. An example of an entity that is quantized is the energy transfer of elementary particles of matter and of photons and other bosons...
to ionize atoms or molecules — that is, to completely remove an
electronAn electron is a subatomic particle that carries a negative electric charge. It has no known substructure and is believed to be a point particle. An electron has a mass that is approximately 1836 times less than that of the proton. The intrinsic angular momentum of the electron is a half integer...
from an
atomThe atom is a basic unit of matter consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
or
moleculeA molecule is defined as an electrically neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds. Molecules are distinguished from polyatomic ions in this strict sense...
. 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.
Non-ionizing radiation or
non-ionising radiation refers to any type of
electromagnetic radiationElectromagnetic radiation is a ubiquitous phenomenon that takes the form of self-propagating waves in a vacuum or in matter. It consists of electric and magnetic field components which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation...
that does not carry enough
energyIn physics, energy is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law...
per
quantumIn physics, a quantum is the minimum unit of any physical entity involved in an interaction. An example of an entity that is quantized is the energy transfer of elementary particles of matter and of photons and other bosons...
to ionize atoms or molecules — that is, to completely remove an
electronAn electron is a subatomic particle that carries a negative electric charge. It has no known substructure and is believed to be a point particle. An electron has a mass that is approximately 1836 times less than that of the proton. The intrinsic angular momentum of the electron is a half integer...
from an
atomThe atom is a basic unit of matter consisting of a dense, central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
or
moleculeA molecule is defined as an electrically neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds. Molecules are distinguished from polyatomic ions in this strict sense...
. 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.
Near ultraviolet, visible light,
infraredInfrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light , but shorter than that of terahertz radiation and microwaves...
,
microwaveMicrowaves are electromagnetic waves with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300MHz and 300 GHz. This is an extremely broad definition including both UHF and EHF , and various sources use different boundaries...
,
radio wavesRadio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
, and low frequency RF (longwave) are all examples of non-ionizing radiation. Visible and near ultraviolet may induce
photochemical reactionIn the area of photochemistry, a photochemical reaction is a chemical reaction that is induced by light. Photochemical reactions are valuable in organic and inorganic chemistry because they proceed differently than thermal reactions. Photochemical reactions are not only very useful but also can be...
s, ionize some molecules or accelerate radical reactions, such as photochemical aging of varnishes or the breakdown of flavoring compounds in beer to produce the 'lightstruck flavor'. The light from the
SunThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
that reaches the earth is largely composed of non-ionizing radiation, with the notable exception of some
ultravioletUltraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
rays. However, most ionizing radiation is filtered out by the atmosphere (see
Earth's atmosphereThe Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
). Static fields do not radiate.
Health risks
Non-ionizing radiation is not mutagenic. The use of this type of radiation in medical fields and everyday life poses fewer health risks than
ionizing radiationIonizing radiation consists of subatomic particles or electromagnetic waves that are energetic enough to detach electrons from atoms or molecules, ionizing them. The occurrence of ionization depends on the energy of the impinging individual particles or waves, and not on their number...
in forms such as
X-rayX-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays...
s. Strong non-ionizing radiation has a heating effect.
In terms of potential biological effects, the non-ionizing portion of the spectrum can be subdivided into:
- The optical radiation portion, where electron excitation can occur (visible light, infrared light)
- The portion where the wavelength is smaller than the body, and heating via induced currents can occur (MW and higher-frequency RF).
- The portion where the wavelength is much larger than the body, and heating via induced currents seldom occurs (lower-frequency RF, power frequencies, static fields)
|
Source |
Wavelength |
Frequency |
Biological Effects |
UVAA black light or UV light is a lamp emitting electromagnetic radiation that is almost exclusively in the soft near ultraviolet range, and emits very little visible light...
|
Black lightA black light or UV light is a lamp emitting electromagnetic radiation that is almost exclusively in the soft near ultraviolet range, and emits very little visible light...
, sunlight |
318 nm - 400 nm |
750 THz - 950 THz |
Eye – Photochemical cataract Skin – Erythema, inc. pigmentation |
| Visible Light |
lasers, sunlight, fireFire is the rapid oxidation of a combustible material releasing heat, light, and various reaction products such as carbon dioxide and water. If hot enough, the gases may become ionized to produce plasma. Depending on the substances alight, and any impurities outside, the color of the flame and the...
, LEDs, Light Bulbs |
400 nm - 780 nm |
385 THz - 750 THz |
Skin photo-ageing; Eye – Photochemical & thermal retinal injury |
IR-AInfrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light , but shorter than that of terahertz radiation and microwaves...
|
lasers, remote controls |
780 nm - 1.4 µm |
215 THz - 385 THz |
Eye – Thermal retinal injury, thermal cataract; Skin burn |
IR-BInfrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light , but shorter than that of terahertz radiation and microwaves...
|
lasers, long-distance telecommunications |
1.4 µm - 3 µm |
100 THz - 215 THz |
Eye – Corneal burn, cataract; Skin burn |
IR-CInfrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light , but shorter than that of terahertz radiation and microwaves...
|
Far-infrared laser |
3 µm - 1 mm |
300 GHz - 100 THz |
Eye – Corneal burn, cataract; Heating of body surface |
MicrowaveMicrowaves are electromagnetic waves with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300MHz and 300 GHz. This is an extremely broad definition including both UHF and EHF , and various sources use different boundaries...
|
PCS phones, some mobile/cell phones, microwave ovens, cordless phones, motion detectors, radar, Wi-Fi Wi-Fi is a trademark of the Wi-Fi Alliance for certified products based on the IEEE 802.11 standards. This certification warrants interoperability between different wireless devices....
|
1 mm - 33 cm |
1 GHz - 300 GHz |
Heating of body tissue. |
Radio Frequency RadiationRadio is the transmission of signals by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...
|
Mobile/Cell phones, television, FM, AM, Shortwave, CB, cordless phones |
33 cm - 3 km |
100 kHz - 1 GHz |
Heating of body tissue, 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 |
strong magnets, MRI |
infinite |
0 Hz |
Magnetic - vertigo/nausea, Electric - charge on body surface |
Ultraviolet radiation
Ultraviolet light can cause
burnsA burn is a type of injury that may be caused by heat, electricity, chemicals, light, radiation, or friction. Burns can be highly variable in terms of the tissue affected, the severity, and resultant complications. Muscle, bone, blood vessel, dermal and epidermal tissue can all be damaged with...
to skin and
cataractA cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light...
s to the eyes. 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
melaninMelanin is a class of compounds found in plants, animals, and protists, where it serves predominantly as a pigment. The class of pigments are derivatives of the amino acid tyrosine. Many melanins are insoluble salts and show affinity to water...
production from
melanocyteMelanocytes are cells located in the bottom layer of the skin's epidermis, the middle layer of the eye , the inner ear, meninges, bones and heart that produce melanin which is a pigment.-Melanogenesis:...
cells to cause
sun tanningSun tanning, also called bronzing, is the act of exposing the skin to ultraviolet radiation, for the purpose of darkening skin color, either during sun bathing or using artificial sources, such as tanning beds....
of skin.
Vitamin DVitamin D is a group of fat-soluble prohormones, the two major forms of which are vitamin D2 and vitamin D3 . Vitamin D obtained from sun exposure, food, and supplements, is biologically inert and must undergo two hydroxylation reactions to be activated in the body...
is produced on the skin by a radical reaction initiated by UV radiation.
Plastic sunglasses (
polycarbonatePolycarbonates are a particular group of thermoplastic polymers. They are easily worked, moulded, and thermoformed; as such, these plastics are very widely used in the modern chemical industry. Their interesting features position them between commodity plastics and engineering plastics...
) generally absorb UV radiation. UV overexposure to the eyes causes
snow blindnessSnow blindness is a painful eye condition, caused by exposure of unprotected eyes to the ultraviolet rays in bright sunlight reflected from snow or ice or less commonly from sea or sand. Fresh snow reflects about 80% of UV radiation compared to a dry, sandy beach or sea foam...
, 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
External links