Editing Ultraviolet (section)

===Biology-related uses===

====Air purification====

UV-C light is used in air conditioning systems as a method of improving indoor air quality by disinfecting the air and preventing microbial growth. UV-C light is effective at killing or inactivating harmful microorganisms, such as bacteria, viruses, mold, and mildew. When integrated into an air conditioning system, the ultraviolet light is typically placed in areas like the [[air handler]] or near the [[Evaporator|evaporator coil]].
In air conditioning systems, UV-C light works by irradiating the airflow within the system, killing or neutralizing harmful microorganisms before they are recirculated into the indoor environment. The effectiveness of it in air conditioning systems depends on factors such as the intensity of the light, the duration of exposure, airflow speed, and the cleanliness of system components.<ref>{{Cite journal |last1=Thornton |first1=Gail M. |last2=Fleck |first2=Brian A. |last3=Fleck |first3=Natalie |last4=Kroeker |first4=Emily |last5=Dandnayak |first5=Dhyey |last6=Zhong |first6=Lexuan |last7=Hartling |first7=Lisa |date=2022-04-08 |title=The impact of heating, ventilation, and air conditioning design features on the transmission of viruses, including the 2019 novel coronavirus: A systematic review of ultraviolet radiation |journal=PLOS ONE |language=en |volume=17 |issue=4 |pages=e0266487 |doi=10.1371/journal.pone.0266487 |doi-access=free |issn=1932-6203 |pmc=8992995 |pmid=35395010|bibcode=2022PLoSO..1766487T }}</ref><ref>{{Cite journal |last1=Abkar |first1=Leili |last2=Zimmermann |first2=Karl |last3=Dixit |first3=Fuhar |last4=Kheyrandish |first4=Ataollah |last5=Mohseni |first5=Madjid |date=2022-11-01 |title=COVID-19 pandemic lesson learned- critical parameters and research needs for UVC inactivation of viral aerosols |journal=Journal of Hazardous Materials Advances |volume=8 |pages=100183 |doi=10.1016/j.hazadv.2022.100183 |issn=2772-4166 |pmc=9553962 |pmid=36619826|bibcode=2022JHzMA...800183A }}</ref>

Using a [[Photocatalysis|catalytic chemical reaction]] from [[titanium dioxide]] and UVC exposure, [[oxidation]] of organic matter converts [[pathogens]], [[pollens]], and [[mold]] [[spores]] into harmless inert byproducts. However, the reaction of titanium dioxide and UVC is not a straight path. Several hundreds of reactions occur prior to the inert byproducts stage and can hinder the resulting reaction creating [[formaldehyde]], aldehyde, and other VOC's en route to a final stage. Thus, the use of titanium dioxide and UVC requires very specific parameters for a successful outcome. The cleansing mechanism of UV is a photochemical process. Contaminants in the indoor environment are almost entirely organic carbon-based compounds, which break down when exposed to high-intensity UV at 240 to 280&nbsp;nm. Short-wave ultraviolet radiation can destroy DNA in living microorganisms.<ref>{{Cite news|url=https://bestledgrowlightsinfo.com/the-importance-of-uv-light-for-plants-cultivated-indoors/|title=The Importance of UV Light for Plants Cultivated Indoors|date=2017-06-11|work=Best LED Grow Lights Info|access-date=2017-06-24|language=en-US|archive-date=30 July 2018|archive-url=https://web.archive.org/web/20180730203142/https://bestledgrowlightsinfo.com/the-importance-of-uv-light-for-plants-cultivated-indoors/|url-status=live}}</ref> UVC's effectiveness is directly related to intensity and exposure time.

UV has also been shown to reduce gaseous contaminants such as [[carbon monoxide]] and [[VOCs]].<ref>{{cite journal |last1=Scott|first1=K.J. |last2=Wills|first2=R.R.H. |last3=Patterson|first3=B.D. |year=1971 |journal=Journal of the Science of Food and Agriculture |doi=10.1002/jsfa.2740220916 |title= Removal by ultra-violet lamp of ethylene and other hydrocarbons produced by bananas |volume=22|pages=496–7|issue=9|bibcode=1971JSFA...22..496S }}</ref><ref>{{cite journal |last1=Scott|first1=KJ |last2=Wills|first2=RBH |title=Atmospheric pollutants destroyed in an ultra violet scrubber |year=1973 |journal=Laboratory Practice|volume=22 |issue=2|pages=103–6 |pmid=4688707}}</ref><ref>{{cite journal |last1=Shorter|first1=AJ |last2=Scott|first2=KJ |year=1986|title=Removal of ethylene from air and low oxygen atmospheres with ultra violet radiation|journal=Lebensm-Wiss U Technology |volume=19|pages=176–9}}</ref> UV lamps radiating at 184 and 254&nbsp;nm can remove low concentrations of [[hydrocarbons]] and [[carbon monoxide]] if the air is recycled between the room and the lamp chamber. This arrangement prevents the introduction of ozone into the treated air. Likewise, air may be treated by passing by a single UV source operating at 184&nbsp;nm and passed over iron pentaoxide to remove the ozone produced by the UV lamp.

====Sterilization and disinfection====
{{Main|Ultraviolet germicidal irradiation|Germicidal lamp}}

[[File:UV-ontsmetting laminaire-vloeikast.JPG|thumb|right|A low-pressure mercury vapor discharge tube floods the inside of a [[Fume hood|hood]] with shortwave UV light when not in use, [[Asepsis|sterilizing]] microbiological contaminants from irradiated surfaces.]]

[[Ultraviolet lamp]]s are used to [[sterilization (microbiology)|sterilize]] workspaces and tools used in biology laboratories and medical facilities. Commercially available low-pressure [[mercury-vapor lamps]] emit about 86% of their radiation at 254 nanometers (nm), with 265&nbsp;nm being the peak germicidal effectiveness curve. UV at these germicidal wavelengths damage a microorganism's DNA/RNA so that it cannot reproduce, making it harmless, (even though the organism may not be killed).<ref>{{cite news |last1=Chang |first1=Kenneth |title=Scientists Consider Indoor Ultraviolet Light to Zap Coronavirus in the Air |url=https://www.nytimes.com/2020/05/07/science/ultraviolet-light-coronavirus.html |archive-url=https://web.archive.org/web/20200507214905/https://www.nytimes.com/2020/05/07/science/ultraviolet-light-coronavirus.html |archive-date=2020-05-07 |url-access=subscription |url-status=live |website=The New York Times |date=7 May 2020 |access-date=9 May 2020}}</ref> Since microorganisms can be shielded from ultraviolet rays in small cracks and other shaded areas, these lamps are used only as a supplement to other sterilization techniques.

UVC LEDs are relatively new to the commercial market and are gaining in popularity.{{Failed verification|date=April 2020}}<ref>{{cite journal|author1=Welch, David |display-authors=et al |title=Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases|journal=Scientific Reports|volume=8|issue=1|pages=2752|doi=10.1038/s41598-018-21058-w|pmid=29426899|pmc=5807439|issn=2045-2322|date=January 2018|bibcode=2018NatSR...8.2752W}}</ref> Due to their monochromatic nature (±5&nbsp;nm){{Failed verification|date=April 2020}} these LEDs can target a specific wavelength needed for disinfection. This is especially important knowing that pathogens vary in their sensitivity to specific UV wavelengths. LEDs are mercury free, instant on/off, and have unlimited cycling throughout the day.<ref>{{cite web|url=https://www.wateronline.com/doc/coming-of-age-uv-c-led-technology-update-0001|title=Coming of Age UV-C LED Technology Update|website=wateronline.com|url-status=live|archive-url=https://web.archive.org/web/20170420045809/https://www.wateronline.com/doc/coming-of-age-uv-c-led-technology-update-0001|archive-date=20 April 2017}}</ref>

[[Disinfection]] using UV radiation is commonly used in [[wastewater]] treatment applications and is finding an increased usage in municipal drinking [[water treatment]]. Many bottlers of spring water use UV disinfection equipment to sterilize their water. [[Solar water disinfection]]<ref>{{cite web |url=http://www.sodis.ch/index_EN |title=Solar Water Disinfection |publisher=Sodis.ch |date=2 April 2011 |access-date=2011-11-08 |url-status=dead |archive-url=https://web.archive.org/web/20120831050355/http://www.sodis.ch/index_EN |archive-date=31 August 2012 }}</ref> has been researched for cheaply treating contaminated water using natural [[sunlight]]. The UVA irradiation and increased water temperature kill organisms in the water.

Ultraviolet radiation is used in several food processes to kill unwanted [[microorganisms]]. UV can be used to [[pasteurize]] fruit juices by flowing the juice over a high-intensity ultraviolet source. The effectiveness of such a process depends on the UV [[absorbance]] of the juice.

[[Pulsed light]] (PL) is a technique of killing microorganisms on surfaces using pulses of an intense broad spectrum, rich in UVC between 200 and 280 [[Nanometer|nm]]. Pulsed light works with [[xenon flash lamp]]s that can produce flashes several times per second. [[Disinfection robot]]s use pulsed UV.<ref>{{cite web|url=http://www.xenex.com/xenex-robot/|title=Video Demos|url-status=dead|archive-url=https://web.archive.org/web/20141219140317/http://www.xenex.com/xenex-robot/|archive-date=19 December 2014|access-date=27 November 2014}}</ref>

The antimicrobial effectiveness of filtered [[far-UVC]] (222 nm) light on a range of pathogens, including bacteria and fungi showed inhibition of pathogen growth, and since it has lesser harmful effects, it provides essential insights for reliable disinfection in healthcare settings, such as hospitals and long-term care homes.<ref>{{Cite journal |last1=Lorenzo-Leal |first1=Ana C. |last2=Tam |first2=Wenxi |last3=Kheyrandish |first3=Ata |last4=Mohseni |first4=Madjid |last5=Bach |first5=Horacio |date=2023-10-31 |editor-last=Barbosa |editor-first=Joana |title=Antimicrobial Activity of Filtered Far-UVC Light (222 nm) against Different Pathogens |journal=BioMed Research International |language=en |volume=2023 |issue=1 |pages=1–8 |doi=10.1155/2023/2085140 |issn=2314-6141 |pmc=10630020 |pmid=37942030 |doi-access=free }}</ref> UVC has also been shown to be effective at degrading SARS-CoV-2 virus.<ref>{{cite journal | doi=10.1021/acsphotonics.3c00828 | title=Mechanisms of SARS-CoV-2 Inactivation Using UVC Laser Radiation | date=2023 | last1=Devitt | first1=George | last2=Johnson | first2=Peter B. | last3=Hanrahan | first3=Niall | last4=Lane | first4=Simon I. R. | last5=Vidale | first5=Magdalena C. | last6=Sheth | first6=Bhavwanti | last7=Allen | first7=Joel D. | last8=Humbert | first8=Maria V. | last9=Spalluto | first9=Cosma M. | last10=Hervé | first10=Rodolphe C. | last11=Staples | first11=Karl | last12=West | first12=Jonathan J. | last13=Forster | first13=Robert | last14=Divecha | first14=Nullin | last15=McCormick | first15=Christopher J. | last16=Crispin | first16=Max | last17=Hempler | first17=Nils | last18=Malcolm | first18=Graeme P. A. | last19=Mahajan | first19=Sumeet | journal=ACS Photonics | volume=11 | issue=1 | pages=42–52 | pmid=38249683 | pmc=10797618 }}</ref>

====Biological====
Some animals, including birds, reptiles, and insects such as bees, can see near-ultraviolet wavelengths. Many fruits, flowers, and seeds stand out more strongly from the background in ultraviolet wavelengths as compared to human color vision. Scorpions glow or take on a yellow to green color under UV illumination, thus assisting in the control of these arachnids. Many birds have patterns in their plumage that are invisible at usual wavelengths but observable in ultraviolet, and the urine and other secretions of some animals, including dogs, cats, and human beings, are much easier to spot with ultraviolet. Urine trails of rodents can be detected by pest control technicians for proper treatment of infested dwellings.

Butterflies use ultraviolet as a [[Ultraviolet communication in butterflies|communication system]] for sex recognition and mating behavior. For example, in the ''[[Colias eurytheme]]'' butterfly, males rely on visual cues to locate and identify females. Instead of using chemical stimuli to find mates, males are attracted to the ultraviolet-reflecting color of female hind wings.<ref>{{cite journal | last1 = Silberglied | first1 = Robert E. | last2 = Taylor | first2 = Orley R. | year = 1978 | title = Ultraviolet Reflection and Its Behavioral Role in the Courtship of the Sulfur Butterflies Colias eurytheme and C. philodice (Lepidoptera, Pieridae) | journal = Behavioral Ecology and Sociobiology | volume = 3 | issue = 3| pages = 203–43 | doi=10.1007/bf00296311| bibcode = 1978BEcoS...3..203S | s2cid = 38043008 }}</ref> In ''[[Pieris napi]]'' butterflies it was shown that females in northern Finland with less UV-radiation present in the environment possessed stronger UV signals to attract their males than those occurring further south. This suggested that it was evolutionarily more difficult to increase the UV-sensitivity of the eyes of the males than to increase the UV-signals emitted by the females.<ref name= "Meyer-Rohow & Järvilehto 1997">{{cite journal| last1=Meyer-Rochow|first1=V.B.|last2=Järvilehto|first2=M.|title=Ultraviolet colours in Pieris napi from northern and southern Finland: Arctic females are the brightest!| journal= Naturwissenschaften|date=1997|volume=84|issue=4|pages= 165–168|bibcode=1997NW.....84..165M|doi=10.1007/s001140050373|s2cid=46142866}}</ref>

Many insects use the ultraviolet wavelength emissions from celestial objects as references for flight navigation. A local ultraviolet emitter will normally disrupt the navigation process and will eventually attract the flying insect.
[[File:ultraviolet trap entomologist.jpg|thumb|right|Entomologist using a UV lamp for collecting [[beetles]] in [[Chaco Department|Chaco]], [[Paraguay]]]]

The [[green fluorescent protein]] (GFP) is often used in [[genetics]] as a marker. Many substances, such as proteins, have significant light absorption bands in the ultraviolet that are of interest in biochemistry and related fields. UV-capable spectrophotometers are common in such laboratories.

Ultraviolet traps called [[bug zapper]]s are used to eliminate various small flying insects. They are attracted to the UV and are killed using an electric shock, or trapped once they come into contact with the device. Different designs of ultraviolet radiation traps are also used by [[entomologists]] for [[collecting]] [[nocturnal]] insects during [[faunistic]] survey studies.

====Therapy====
{{main|Ultraviolet light therapy}}
Ultraviolet radiation is helpful in the treatment of [[skin conditions]] such as [[psoriasis]] and [[vitiligo]]. Exposure to UVA, while the skin is hyper-photosensitive, by taking [[psoralen]]s is an effective treatment for [[psoriasis]]. Due to the potential of [[psoralens]] to cause damage to the [[liver]], [[PUVA therapy]] may be used only a limited number of times over a patient's lifetime.

UVB phototherapy does not require additional medications or topical preparations for the therapeutic benefit; only the exposure is needed. However, phototherapy can be effective when used in conjunction with certain topical treatments such as anthralin, coal tar, and [[vitamin A]] and D derivatives, or systemic treatments such as [[methotrexate]] and [[Soriatane]].<ref>
{{cite web |title = UVB Phototherapy |url = http://www.psoriasis.org/treatment/psoriasis/phototherapy/uvb.php |archive-url=https://web.archive.org/web/20070622180124/http://www.psoriasis.org/treatment/psoriasis/phototherapy/uvb.php |archive-date=22 June 2007 |format=php |access-date=2007-09-23 |publisher=National Psoriasis Foundation, USA}}</ref>

====Herpetology====
[[Reptile]]s need UVB for biosynthesis of vitamin D, and other metabolic processes.<ref>{{Cite journal |last1=Diehl |first1=J. J. E. |last2=Baines |first2=F. M. |last3=Heijboer |first3=A. C. |last4=van Leeuwen |first4=J. P. |last5=Kik |first5=M. |last6=Hendriks |first6=W. H. |last7=Oonincx |first7=D. G. A. B. |date=February 2018 |title=A comparison of UVb compact lamps in enabling cutaneous vitamin D synthesis in growing bearded dragons |journal=Journal of Animal Physiology and Animal Nutrition |language=en |volume=102 |issue=1 |pages=308–316 |doi=10.1111/jpn.12728 |pmid=28452197 |s2cid=30124686 |doi-access=free |url=https://dspace.library.uu.nl/bitstream/handle/1874/360841/Diehl_et_al_2018_Journal_of_Animal_Physiology_and_Animal_Nutrition_1_.pdf?sequence=1&isAllowed=y }}</ref> Specifically [[cholecalciferol]] (vitamin D3), which is needed for basic cellular / neural functioning as well as the utilization of calcium for bone and egg production.{{Citation needed|date=April 2022}} The UVA wavelength is also visible to many reptiles and might play a significant role in their ability survive in the wild as well as in visual communication between individuals.{{Citation needed|date=April 2022}} Therefore, in a typical reptile enclosure, a fluorescent UV a/b source (at the proper strength / spectrum for the species), must be available for many{{Which|date=April 2022}} captive species to survive. Simple supplementation with [[cholecalciferol]] (Vitamin D3) will not be enough as there is a complete biosynthetic pathway{{Which|date=May 2022}} that is "leapfrogged" (risks of possible overdoses), the intermediate molecules and metabolites{{Which|date=April 2022}} also play important functions in the animals health.{{Citation needed|date=April 2022}} Natural sunlight in the right levels is always going to be superior to artificial sources, but this might not be possible for keepers in different parts of the world.{{Citation needed|date=April 2022}}

It is a known problem that high levels of output of the UVa part of the spectrum can both cause cellular and DNA damage to sensitive parts of their bodies – especially the eyes where blindness is the result of an improper UVa/b source use and placement [[photokeratitis]].{{Citation needed|date=April 2022}} For many keepers there must also be a provision for an adequate heat source this has resulted in the marketing of heat and light "combination" products.{{Citation needed|date=April 2022}} Keepers should be careful of these "combination" light/ heat and UVa/b generators, they typically emit high levels of UVa with lower levels of UVb that are set and difficult to control so that animals can have their needs met.{{Citation needed|date=April 2022}} A better strategy is to use individual sources of these elements and so they can be placed and controlled by the keepers for the max benefit of the animals.<ref>{{cite web|url=http://www.uvguide.co.uk/vitdpathway.htm|title=Vitamin D and Ultraviolet Light – a remarkable process|website=UV Guide UK|access-date=2017-01-13|url-status=live|archive-url=https://web.archive.org/web/20160531172209/http://www.uvguide.co.uk/vitdpathway.htm|archive-date=31 May 2016}}</ref>