Ultraviolet

{{physics}}
'''Ultraviolet''' ('''UV''') light, sometimes called '''black light''', is a form of non-visible [[Radiation#Electromagnetic|electromagnetic radiation]], with wavelengths just shorter than the violet/blue end of visible light. It occupies wavelengths between around 10 and 400 nanometres, or around 10<sup>15</sup>–10<sup>16</sup> Hertz.

Surprisingly, the human retina is sensitive to ultraviolet; however the lens is opaque to it, which means that individuals who have had their lenses removed (such as for severe cataracts) can see in the ultraviolet.<ref>https://petapixel.com/2012/04/17/the-human-eye-can-see-in-ultraviolet-when-the-lens-is-removed/</ref> Claude Monet's later paintings, following lens removal, underwent a radical change, likely the result of his being able to see patterns in flowers, scenery, etc. that are invisible to the rest of us.<ref>https://www.sciencehistory.org/distillations/could-claude-monet-see-like-a-bee</ref>

==Classification==
The ultraviolet spectrum is typically divided into four ranges:

* '''UV-A''', from 400 – 315 nanometers. This is the "softest" UV, used by black lights and tanning salons.
* '''UV-B''', from 315 – 280 nm. This is the range that causes sunburns. It's also the range that your skin turns into [[vitamin D]].
* '''UV-C''', from 280 – 200 nm. This range is germicidal, and can be used in disinfection, including the [[food irradiation]] of fresh-pressed apple cider.
* '''Vacuum UV''', from 200 - 100 nm. This range is absobed by atmospheric oxygen, and thus is only good at propagating through a vacuum.
* '''Extreme UV''', from about 121 nm down to 10 nm. This is the "hardest" of the ultraviolet frequency ranges. It's scattered in air, and is ionizing radiation. Any radiation of shorter wavelength than 10 nm is considered X-rays, or gamma rays.

==Health==
Ultraviolet is known to cause damage to skin. For prolonged exposure to the [[sun]], some individuals may receive sunburn, or receive damage to the eyes. Despite the hazardous effects &mdash; or rather, ''because'' of them &mdash; it may be used to kill [[Bacteria|germs]] in irradiation systems.

Ultraviolet radiation (UV-A, UV-B, and UV-C) causes both skin and eye [[cancer]] (melanoma).<ref>[https://www.iarc.fr/en/media-centre/iarcnews/2009/sunbeds_uvradiation.php Sunbeds and UV Radiation] (29/07/2009) International Agency for Research on Cancer</ref><ref>[https://www.iarc.fr/en/publications/pdfs-online/wrk/wrk1/ArtificialUVRad&SkinCancer.pdf Exposure to Artificial UV Radiation and Skin Cancer] (2006) International Agency for Research on Cancer</ref> Remember that the next time you lie down in a tanning booth.

No, it can’t cure [[coronavirus]].<ref name="zaria">Gorvett, Zaria. [https://www.bbc.com/future/article/20200327-can-you-kill-coronavirus-with-uv-light Can you kill coronavirus with UV light?] ''BBC''. April 24, 2020.</ref> Only UV-C is effective for disinfection, and it causes as much skin damage in seconds as sunlight can cause in hours.<ref name="zaria" />

Younger people are much more as vulnerable to cell mutations from tanning bed UV, mutations potentially that lead to cancer.<ref>[https://www.sfchronicle.com/health/article/tanning-beds-young-mutations-21244376.php ‘Two lifetimes’ of UV damage: UCSF study shows what tanning beds do to young skin] by Catherine Ho (Dec 15, 2025) ''San Francisco Chronicle''.</ref>

==References==
{{reflist}}

{{sources needed}}
{{stub|science}}

[[Category:Human carcinogens]]
[[Category:Science]]

Categories: Human carcinogens, Science