Editing Ultraviolet (section)

====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.