far-UVC

Far-UVC's development was primarily led by the research of Dr. David J. Brenner and his colleagues (including David Welch and Manuela Buonanno) at Columbia University's Center for Radiological Research. In the early 2010s, Brenner initially studied far-UVC for its potential as a surgical site disinfectant.{{Cite journal |last1=Buonanno |first1=Manuela |last2=Randers-Pehrson |first2=Gerhard |last3=Bigelow |first3=Alan W. |last4=Trivedi |first4=Sheetal |last5=Lowy |first5=Franklin D. |last6=Spotnitz |first6=Henry M. |last7=Hammer |first7=Scott M. |last8=Brenner |first8=David J. |date=2013-10-16 |title=207-nm UV Light – A Promising Tool for Safe Low-Cost Reduction of Surgical Site Infections. I: In Vitro Studies |journal=PLOS ONE |volume=8 |issue=10 |pages=e76968 |doi=10.1371/journal.pone.0076968 |doi-access=free |issn=1932-6203 |pmc=3797730 |pmid=24146947|bibcode=2013PLoSO...876968B }} Over the next decade, his lab began to study the technology for its ability to prevent the airborne transmission of pathogens, as well as its health effects on mammalian skin.{{Cite journal |last1=Buonanno |first1=Manuela |last2=Ponnaiya |first2=Brian |last3=Welch |first3=David |last4=Stanislauskas |first4=Milda |last5=Randers-Pehrson |first5=Gerhard |last6=Smilenov |first6=Lubomir |last7=Lowy |first7=Franklin D. |last8=Owens |first8=David M. |last9=Brenner |first9=David J. |date=April 2017 |title=Germicidal Efficacy and Mammalian Skin Safety of 222-nm UV Light |journal=Radiation Research |volume=187 |issue=4 |pages=483–491 |doi=10.1667/RR0010CC.1 |issn=0033-7587 |pmc=5552051 |pmid=28225654|bibcode=2017RadR..187..493B }} In 2018, a seminal paper published by Brenner's lab announced the technology as an inexpensive and safe technology to reduce the spread of airborne microbial diseases like tuberculosis and influenza.

During the COVID-19 pandemic far-UVC research and commercialization efforts increased.{{Cite journal |last1=Welch |first1=David |last2=Buonanno |first2=Manuela |last3=Buchan |first3=Andrew G. |last4=Yang |first4=Liang |last5=Atkinson |first5=Kirk D. |last6=Shuryak |first6=Igor |last7=Brenner |first7=David J. |date=April 2022 |title=Inactivation Rates for Airborne Human Coronavirus by Low Doses of 222 nm Far-UVC Radiation |journal=Viruses |volume=14 |issue=4 |pages=684 |doi=10.3390/v14040684 |doi-access=free |pmid=35458414 |pmc=9030991 |issn=1999-4915}} The technology is currently being further studied for its safety and efficacy, particularly regarding its effect on ozone creation and interactions with indoor air chemistry and the built environment.{{Cite journal |last1=Peng |first1=Zhe |last2=Day |first2=Douglas A. |last3=Symonds |first3=Guy A. |last4=Jenks |first4=Olivia J. |last5=Stark |first5=Harald |last6=Handschy |first6=Anne V. |last7=de Gouw |first7=Joost A. |last8=Jimenez |first8=Jose L. |date=2023-08-08 |title=Significant Production of Ozone from Germicidal UV Lights at 222 nm |url=https://pubs.acs.org/doi/10.1021/acs.estlett.3c00314 |journal=Environmental Science & Technology Letters |volume=10 |issue=8 |pages=668–674 |doi=10.1021/acs.estlett.3c00314 |bibcode=2023EnSTL..10..668P |issn=2328-8930 |access-date=2024-07-22 |archive-date=2024-04-03 |archive-url=https://web.archive.org/web/20240403231554/https://pubs.acs.org/doi/10.1021/acs.estlett.3c00314 |url-status=live }}{{Cite journal |last1=Drungilas |first1=Darius |last2=Kurmis |first2=Mindaugas |last3=Tadzijevas |first3=Arturas |last4=Lukosius |first4=Zydrunas |last5=Martinkenas |first5=Arvydas |last6=Didziokas |first6=Rimantas |last7=Gruode |first7=Jurate |last8=Sapalas |first8=Deivydas |last9=Jankunas |first9=Valdas |date=January 2023 |title=Evaluating the Impact of 222 nm Far-UVC Radiation on the Aesthetic and Mechanical Properties of Materials Used in Public Bus Interiors |journal=Applied Sciences |volume=13 |issue=7 |pages=4141 |doi=10.3390/app13074141 |doi-access=free |issn=2076-3417}} Latest studies uphold initial evidence towards the technology's germicidal efficacy in realistic room-like environments. These finding pave the way for future wearable garments which can disinfect a programmable area in the vicinity of the user on demand.{{Cite book |last1=Robertson |first1=Ryan D. |last2=Pratt |first2=Layton C. |last3=Mintchev |first3=Martin P. |chapter=Evaluating the Disinfecting Capabilities of an Interconnected Wearable Far UVC Vest |date=July 2024 |title=2024 IEEE International Conference on Microwaves, Communications, Antennas, Biomedical Engineering and Electronic Systems (COMCAS) |chapter-url=https://ieeexplore.ieee.org/document/10666256 |pages=1–4 |doi=10.1109/COMCAS58210.2024.10666256|isbn=979-8-3503-4818-7 }}

Research from the Brenner lab and other scientists has demonstrated the improved safety and efficacy profile of far-UVC compared to other ultraviolet wavelengths. A 2025 review article concluded that the wavelength of 222nm had a "high ability" to kill pathogens, and a "high level of safety", but that further research was required on the effects of long-term exposure before widespread use, as well as further research on its efficacy in real-world scenarios, as opposed to laboratory conditions.{{Cite journal |last1=Arzanani |first1=Kimia Ghasemi |last2=Rashidian Vaziri |first2=Mohammad Reza |last3=Sharif |first3=Samaneh |last4=Mollaee |first4=Masoud |date=2025-02-11 |title=A review on applications and safety of 222 nm far UVC light for surface and air disinfection |url=https://link.springer.com/article/10.1007/s12551-025-01269-y |journal=Biophysical Reviews |language=en |doi=10.1007/s12551-025-01269-y |issn=1867-2469|url-access=subscription }}

When evaluating ultraviolet germicidal lights, eye and skin health are primary concerns. UV-B, predominantly responsible for the harmful effects of sunlight, poses the highest risk for erythema, photokeratitis, sunburn and skin cancer.{{Cite journal |last1=Ikehata |first1=Hironobu |last2=Mori |first2=Toshio |last3=Kamei |first3=Yasuhiro |last4=Douki |first4=Thierry |last5=Cadet |first5=Jean |last6=Yamamoto |first6=Masayuki |date=January 2020 |title=Wavelength- and Tissue-dependent Variations in the Mutagenicity of Cyclobutane Pyrimidine Dimers in Mouse Skin |url=https://onlinelibrary.wiley.com/doi/10.1111/php.13159 |journal=Photochemistry and Photobiology |volume=96 |issue=1 |pages=94–104 |doi=10.1111/php.13159 |pmid=31461538 |issn=0031-8655 |url-access=subscription |access-date=2024-07-25 |archive-date=2024-01-28 |archive-url=https://web.archive.org/web/20240128020817/https://onlinelibrary.wiley.com/doi/10.1111/php.13159 |url-status=live }}{{Cite journal |last=Rochette |first=P. J. |date=2003-06-01 |title=UVA-induced cyclobutane pyrimidine dimers form predominantly at thymine-thymine dipyrimidines and correlate with the mutation spectrum in rodent cells |journal=Nucleic Acids Research |volume=31 |issue=11 |pages=2786–2794 |doi=10.1093/nar/gkg402 |pmc=156735 |pmid=12771205}}{{Cite web |title=UV-C photocarcinogenesis risks from germicidal lamps {{!}} CIE |url=https://cie.co.at/publications/uv-c-photocarcinogenesis-risks-germicidal-lamps |access-date=2024-07-25 |website=cie.co.at |archive-date=2024-07-25 |archive-url=https://web.archive.org/web/20240725150857/https://cie.co.at/publications/uv-c-photocarcinogenesis-risks-germicidal-lamps |url-status=live }} While longer UV-C wavelengths and UV-A can also cause damage, their effects are less severe than UV-B.

In contrast, far-UVC has shown remarkably different results. Studies on both lab mice and humans have found no significant impact on skin health,{{Cite journal |last=Cadet |first=Jean |date=July 2020 |title=Harmless Effects of Sterilizing 222-nm far-UV Radiation on Mouse Skin and Eye Tissues |url=https://pubmed.ncbi.nlm.nih.gov/32526045/ |journal=Photochemistry and Photobiology |volume=96 |issue=4 |pages=949–950 |doi=10.1111/php.13294 |issn=1751-1097 |pmid=32526045 |access-date=2024-07-22 |archive-date=2024-07-22 |archive-url=https://web.archive.org/web/20240722132353/https://pubmed.ncbi.nlm.nih.gov/32526045/ |url-status=live }}{{Cite journal |last1=Welch |first1=David |last2=Kleiman |first2=Norman J. |last3=Arden |first3=Peter C. |last4=Kuryla |first4=Christine L. |last5=Buonanno |first5=Manuela |last6=Ponnaiya |first6=Brian |last7=Wu |first7=Xuefeng |last8=Brenner |first8=David J. |date=January 2023 |title=No Evidence of Induced Skin Cancer or Other Skin Abnormalities after Long-Term (66 week) Chronic Exposure to 222-nm Far-UVC Radiation |journal=Photochemistry and Photobiology |volume=99 |issue=1 |pages=168–175 |doi=10.1111/php.13656 |issn=0031-8655 |pmc=9691791 |pmid=35614842}} even at doses far exceeding current guidelines.{{Cite journal |last1=Eadie |first1=Ewan |last2=Barnard |first2=Isla M. R. |last3=Ibbotson |first3=Sally H. |last4=Wood |first4=Kenneth |date=May 2021 |title=Extreme Exposure to Filtered Far-UVC: A Case Study † |journal=Photochemistry and Photobiology |volume=97 |issue=3 |pages=527–531 |doi=10.1111/php.13385 |issn=0031-8655 |pmc=8638665 |pmid=33471372}} This enhanced safety is attributed to far-UVC's difficulty in penetrating the outermost layer of the epidermis called the stratum corneum. The stratum corneum is effective at blocking far-UVC as it's composed primarily of dead cells filled with keratin protein, which absorb far-UVC light.

Regarding ocular safety, while comprehensive human studies are still pending, limited research has been conducted on human eye exposure to overhead far-UVC lamps. These studies have found no evidence of damage or increased discomfort.{{Cite journal |last1=Sugihara |first1=Kazunobu |last2=Kaidzu |first2=Sachiko |last3=Sasaki |first3=Masahiro |last4=Ichioka |first4=Sho |last5=Takayanagi |first5=Yuji |last6=Shimizu |first6=Hiroshi |last7=Sano |first7=Ichiya |last8=Hara |first8=Katsunori |last9=Tanito |first9=Masaki |date=May 2023 |title=One-year Ocular Safety Observation of Workers and Estimations of Microorganism Inactivation Efficacy in the Room Irradiated with 222-nm Far Ultraviolet-C Lamps |journal=Photochemistry and Photobiology |volume=99 |issue=3 |pages=967–974 |doi=10.1111/php.13710 |pmid=36081379 |issn=0031-8655 |doi-access=free }}{{Cite journal |last1=Kousha |first1=Obaid |last2=O'Mahoney |first2=Paul |last3=Hammond |first3=Robert |last4=Wood |first4=Kenneth |last5=Eadie |first5=Ewan |date=January 2024 |title=222 nm F ar- UVC from filtered K rypton- C hloride excimer lamps does not cause eye irritation when deployed in a simulated office environment |journal=Photochemistry and Photobiology |volume=100 |issue=1 |pages=137–145 |doi=10.1111/php.13805 |issn=0031-8655 |pmc=10952573 |pmid=37029739}} Additionally, research on rats has revealed significantly reduced penetration and damage from far-UVC compared to other UV wavelengths.{{Cite journal |last1=Kaidzu |first1=Sachiko |last2=Sugihara |first2=Kazunobu |last3=Sasaki |first3=Masahiro |last4=Nishiaki |first4=Aiko |last5=Ohashi |first5=Hiroyuki |last6=Igarashi |first6=Tatsushi |last7=Tanito |first7=Masaki |date=May 2021 |title=Re-Evaluation of Rat Corneal Damage by Short-Wavelength UV Revealed Extremely Less Hazardous Property of Far-UV-C † |journal=Photochemistry and Photobiology |volume=97 |issue=3 |pages=505–516 |doi=10.1111/php.13419 |issn=0031-8655 |pmc=8251618 |pmid=33749837}}{{Cite journal |last1=Kaidzu |first1=Sachiko |last2=Sugihara |first2=Kazunobu |last3=Sasaki |first3=Masahiro |last4=Nishiaki |first4=Aiko |last5=Ohashi |first5=Hiroyuki |last6=Igarashi |first6=Tatsushi |last7=Tanito |first7=Masaki |date=July 2023 |title=Safety Evaluation of Far-UV-C Irradiation to Epithelial Basal Cells in the Corneal Limbus |journal=Photochemistry and Photobiology |volume=99 |issue=4 |pages=1142–1148 |doi=10.1111/php.13750 |pmid=36437576 |issn=0031-8655 |doi-access=free }} These findings suggest a promising safety profile for far-UVC, though further research, particularly on human eyes, is needed to fully establish its long-term effects.

When far-UVC interacts with airborne oxygen it produces ozone and other byproducts,{{Cite journal |last1=Link |first1=Michael F. |last2=Shore |first2=Andrew |last3=Hamadani |first3=Behrang H. |last4=Poppendieck |first4=Dustin |date=2023-08-08 |title=Ozone Generation from a Germicidal Ultraviolet Lamp with Peak Emission at 222 nm |journal=Environmental Science & Technology Letters |volume=10 |issue=8 |pages=675–679 |bibcode=2023EnSTL..10..675L |doi=10.1021/acs.estlett.3c00318 |issn=2328-8930 |pmc=10938353 |pmid=38487621}}{{Cite journal |last1=Barber |first1=Victoria P. |last2=Goss |first2=Matthew B. |last3=Franco Deloya |first3=Lesly J. |last4=LeMar |first4=Lexy N. |last5=Li |first5=Yaowei |last6=Helstrom |first6=Erik |last7=Canagaratna |first7=Manjula |last8=Keutsch |first8=Frank N. |last9=Kroll |first9=Jesse H. |date=2023-10-24 |title=Indoor Air Quality Implications of Germicidal 222 nm Light |journal=Environmental Science & Technology |language=en |volume=57 |issue=42 |pages=15990–15998 |doi=10.1021/acs.est.3c05680 |issn=0013-936X |pmc=10607233 |pmid=37827494|bibcode=2023EnST...5715990B }}{{Cite journal |last1=Jenks |first1=Olivia J. |last2=Peng |first2=Zhe |last3=Schueneman |first3=Melinda K. |last4=Rutherford |first4=Madison |last5=Handschy |first5=Anne V. |last6=Day |first6=Douglas A. |last7=Jimenez |first7=Jose L. |last8=de Gouw |first8=Joost A. |date=2024-07-12 |title=Effects of 222 nm Germicidal Ultraviolet Light on Aerosol and VOC Formation from Limonene |journal=ACS ES&T Air |language=en |volume=1 |issue=7 |pages=725–733 |doi=10.1021/acsestair.4c00065 |issn=2837-1402 |pmc=11249781 |pmid=39021671|bibcode=2024ACSES...1..725J }}{{Citation |last1=Link |first1=Michael F. |title=Ozone Generation from a Germicidal Ultraviolet Lamp with Peak Emission at 222 nm |date=2023-05-25 |url=https://www.medrxiv.org/content/10.1101/2023.05.17.23290115v1 |access-date=2024-07-30 |language=en |doi=10.1101/2023.05.17.23290115 |last2=Shore |first2=Andrew |last3=Hamadani |first3=Behrang H. |last4=Poppendieck |first4=Dustin |archive-date=2024-07-30 |archive-url=https://web.archive.org/web/20240730212728/https://www.medrxiv.org/content/10.1101/2023.05.17.23290115v1 |url-status=live }} an effect that has been demonstrated in laboratory and real world environments.{{Cite journal |last1=Link |first1=Michael F. |last2=Robertson |first2=Rileigh L. |last3=Shore |first3=Andrew |last4=Hamadani |first4=Behrang H. |last5=Cecelski |first5=Christina E. |last6=Poppendieck |first6=Dustin G. |date=2024-06-19 |title=Ozone generation and chemistry from 222 nm germicidal ultraviolet light in a fragrant restroom |journal=Environmental Science: Processes & Impacts |language=en |volume=26 |issue=6 |pages=1090–1106 |doi=10.1039/D4EM00144C |pmid=38787731 |pmc=11421862 |issn=2050-7895 }}{{Citation |last1=Narouei |first1=Farideh |title=Effects of Germicidal Far-UVC on Indoor Air Quality in an Office Setting |date=2024-06-03 |url=https://chemrxiv.org/engage/chemrxiv/article-details/665a5c8d91aefa6ce17d493a |access-date=2024-07-30 |language=en |doi=10.26434/chemrxiv-2024-l6k59 |last2=Tang |first2=Zifeng |last3=Wang |first3=Shiqi |last4=Hashmi |first4=Raabia |last5=Welch |first5=David |last6=Sethuraman |first6=Sandhya |last7=Brenner |first7=David |last8=McNeill |first8=V. Faye |archive-date=2024-07-30 |archive-url=https://web.archive.org/web/20240730212725/https://chemrxiv.org/engage/chemrxiv/article-details/665a5c8d91aefa6ce17d493a |url-status=live |doi-access=free }}{{Citation |last1=Kalliomäki |first1=Petri |title=Ozone and ultra-fine particle concentrations in a hotel quarantine facility during 222 nm far-UVC air disinfection |date=2023-10-02 |url=https://www.medrxiv.org/content/10.1101/2023.09.29.23296366v1 |access-date=2024-07-30 |language=en |doi=10.1101/2023.09.29.23296366 |last2=Sobhani |first2=Hamed |last3=Stratton |first3=Phillip |last4=Coleman |first4=Kristen K. |last5=Srikakulapu |first5=Aditya |last6=Salawitch |first6=Ross |last7=Dickerson |first7=Russell R. |last8=Zhu |first8=Shengwei |last9=Srebric |first9=Jelena |archive-date=2024-07-30 |archive-url=https://web.archive.org/web/20240730212719/https://www.medrxiv.org/content/10.1101/2023.09.29.23296366v1 |url-status=live |doi-access=free }} While the extent to which this produced ozone leads to negative health effects is the subject of active research,{{Cite web |title=White Paper: Air Pollutant Emissions and Possible Health Effects Associated with Electronic Air Cleaning Devices {{!}} California Air Resources Board |url=https://ww2.arb.ca.gov/white-paper-air-pollutant-emissions-and-possible-health-effects-associated-electronic-air-cleaning |access-date=2024-07-30 |website=ww2.arb.ca.gov |archive-date=2024-07-30 |archive-url=https://web.archive.org/web/20240730212719/https://ww2.arb.ca.gov/white-paper-air-pollutant-emissions-and-possible-health-effects-associated-electronic-air-cleaning |url-status=live }}{{Cite journal |last1=Weschler |first1=Charles J. |last2=Nazaroff |first2=William W |date=2023-09-12 |title=Ozone Loss: A Surrogate for the Indoor Concentration of Ozone-Derived Products |url=https://escholarship.org/content/qt1dj654bk/qt1dj654bk.pdf?t=rzrcah |journal=Environmental Science & Technology |language=en |volume=57 |issue=36 |pages=13569–13578 |doi=10.1021/acs.est.3c03968 |pmid=37639667 |bibcode=2023EnST...5713569W |issn=0013-936X |access-date=2024-08-07 |archive-date=2024-08-07 |archive-url=https://web.archive.org/web/20240807214819/https://escholarship.org/content/qt1dj654bk/qt1dj654bk.pdf?t=rzrcah |url-status=live }}{{Cite journal |last1=He |first1=Linchen |last2=Weschler |first2=Charles J. |last3=Morrison |first3=Glenn |last4=Li |first4=Feng |last5=Zhang |first5=Yinping |last6=Bergin |first6=Michael H. |last7=Black |first7=Marilyn |last8=Zhang |first8=Junfeng Jim |date=2024-06-18 |title=Synergistic Effects of Ozone Reaction Products and Fine Particulate Matter on Respiratory Pathophysiology in Children with Asthma |journal=ACS ES&T Air |volume=1 |issue=8 |pages=918–926 |language=en |doi=10.1021/acsestair.4c00080 |issn=2837-1402 |doi-access=free }} the mechanism for ozone causing cardiovascular disease and premature mortality is established in outdoor settings.{{Cite journal |last1=Turner |first1=Michelle C. |last2=Jerrett |first2=Michael |last3=Pope |first3=C. Arden |last4=Krewski |first4=Daniel |last5=Gapstur |first5=Susan M. |last6=Diver |first6=W. Ryan |last7=Beckerman |first7=Bernardo S. |last8=Marshall |first8=Julian D. |last9=Su |first9=Jason |last10=Crouse |first10=Daniel L. |last11=Burnett |first11=Richard T. |date=2016-05-15 |title=Long-Term Ozone Exposure and Mortality in a Large Prospective Study |journal=American Journal of Respiratory and Critical Care Medicine |volume=193 |issue=10 |pages=1134–1142 |doi=10.1164/rccm.201508-1633OC |issn=1535-4970 |pmc=4872664 |pmid=26680605}}

A key concern for far-UVC implementations is balancing radiation dosage and microbial inactivation rates.{{Cite journal |last1=Ryan |first1=Kevin |last2=McCabe |first2=Kevin |last3=Clements |first3=Nick |last4=Hernandez |first4=Mark |last5=Miller |first5=Shelly L. |date=2010-06-04 |title=Inactivation of Airborne Microorganisms Using Novel Ultraviolet Radiation Sources in Reflective Flow-Through Control Devices |url=http://www.tandfonline.com/doi/abs/10.1080/02786821003762411 |journal=Aerosol Science and Technology |volume=44 |issue=7 |pages=541–550 |doi=10.1080/02786821003762411 |bibcode=2010AerST..44..541R |issn=0278-6826}} Although far-UVC has been shown to be effective at inactivating a wide array at viruses at doses that fall beneath exposure limits,{{Cite journal |last1=Ma |first1=Ben |last2=Bright |first2=Kelly |last3=Ikner |first3=Luisa |last4=Ley |first4=Christian |last5=Seyedi |first5=Saba |last6=Gerba |first6=Charles P. |last7=Sobsey |first7=Mark D. |last8=Piper |first8=Patrick |last9=Linden |first9=Karl G. |date=2023 |title=UV Inactivation of Common Pathogens and Surrogates Under 222 nm Irradiation from KrCl* Excimer Lamps |url=https://pubmed.ncbi.nlm.nih.gov/36129750/ |journal=Photochemistry and Photobiology |volume=99 |issue=3 |pages=975–982 |doi=10.1111/php.13724 |issn=1751-1097 |pmid=36129750 |access-date=2024-07-22 |archive-date=2024-07-22 |archive-url=https://web.archive.org/web/20240722132353/https://pubmed.ncbi.nlm.nih.gov/36129750/ |url-status=live }}{{Cite journal |last1=Allen |first1=Gary R. |last2=Benner |first2=Kevin J. |last3=Bahnfleth |first3=William P. |date=2021 |title=Inactivation of Pathogens in Air Using Ultraviolet Direct Irradiation Below Exposure Limits |journal=Journal of Research of the National Institute of Standards and Technology |volume=126 |pages=126052 |doi=10.6028/jres.126.052 |issn=1044-677X |pmid=38469440|pmc=10046823 }} the optimal dosage for achieving sufficient deactivation and indoor air quality standards requires further study.{{Cite web |title=ASHRAE Completes Draft of First-Ever Pathogen Mitigation Standard |url=https://www.ashrae.org/about/news/2023/ashrae-completes-draft-of-first-ever-pathogen-mitigation-standard |access-date=2024-07-22 |website=www.ashrae.org |archive-date=2024-07-22 |archive-url=https://web.archive.org/web/20240722132401/https://www.ashrae.org/about/news/2023/ashrae-completes-draft-of-first-ever-pathogen-mitigation-standard |url-status=live }}

Positive skin and eye safety attributes can be forgone if a given far-UVC lamp produces unwanted emissions at wavelengths other than the a device's stated specifications. For this reason, optical filters have been suggested as a mitigation device.{{Cite journal |last1=Eadie |first1=Ewan |last2=O'Mahoney |first2=Paul |last3=Ibbotson |first3=Sally H. |last4=Miller |first4=C. Cameron |last5=Wood |first5=Kenneth |date=2024-07-20 |title=Far-UVC: The impact of optical filters on real-world deployment |url=https://pubmed.ncbi.nlm.nih.gov/39032065/ |journal=Photochemistry and Photobiology |volume=101 |issue=2 |pages=270–274 |doi=10.1111/php.14005 |issn=1751-1097 |pmid=39032065 |access-date=2024-07-30 |archive-date=2024-07-30 |archive-url=https://web.archive.org/web/20240730212719/https://pubmed.ncbi.nlm.nih.gov/39032065/ |url-status=live }} Mitigation techniques also have been studied for ozone production.{{Cite journal |last1=Weschler |first1=Charles J. |last2=Shields |first2=Helen C. |last3=Naik |first3=Datta V. |date=1994 |title=Ozone-removal efficiencies of activated carbon filters after more than three years of continuous service |url=http://dx.doi.org/10.1080/08940630.1989.10466650 |journal=ASHRAE Transactions 1994: Technical and Symposium Papers. |volume=39 |issue=12 |pages=1562–1568 |doi=10.1080/08940630.1989.10466650 |pmid=2607364 |issn=0894-0630 |url-access=subscription |access-date=2024-07-30 |archive-date=2024-08-07 |archive-url=https://web.archive.org/web/20240807215325/https://www.tandfonline.com/doi/abs/10.1080/08940630.1989.10466650 |url-status=live }}File:Indoor Far-UVC Device Implementation.jpg is used to disinfect the air in a National Guard facility.]]

The most common device used to generate far-UVC radiation is a Krypton Chloride (KrCl) excimer lamp, which emits light at the 222 nm wavelength. Following the sudden increase in demand for disinfectant tools brought upon by the COVID-19 pandemic, a number of companies began to market and sell consumer far-UVC devices. These devices come in many different configurations and commercial form factors. There are no public estimates available for the size of the far-UVC device industry.

Considering the technology's evolving nature, regulatory bodies around the world have not yet created binding standards as to what is considered a safe and effective dosage for far-UVC implementations, nor have they created certifications or passed regulations for the safety of commercial far-UVC devices. Legislation has been proposed for governing the production of ozone from germicidal UV light in California.{{Cite web |title=Bill Text – SB-1308 Ozone: indoor air cleaning devices. |url=https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=202320240SB1308 |access-date=2024-07-30 |website=leginfo.legislature.ca.gov |archive-date=2024-07-30 |archive-url=https://web.archive.org/web/20240730212719/https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=202320240SB1308 |url-status=live }} In lieu of formal regulations or standards, guidelines for exposure limits and indoor air quality are put in place by professional associations.{{Cite web |title=ASHRAE Standard 241, Control of Infectious Aerosols {{!}} ashrae.org |url=https://www.ashrae.org/technical-resources/bookstore/ashrae-standard-241-control-of-infectious-aerosols |access-date=2024-07-22 |website=www.ashrae.org |archive-date=2024-07-22 |archive-url=https://web.archive.org/web/20240722132401/https://www.ashrae.org/technical-resources/bookstore/ashrae-standard-241-control-of-infectious-aerosols |url-status=live }}{{Cite journal |last=on Non-Ionizing Radiation Protection |first=International Commission |date=2010 |title=ICNIRP STATEMENT—PROTECTION OF WORKERS AGAINST ULTRAVIOLET RADIATION |url=https://journals.lww.com/health-physics/citation/2010/07000/icnirp_statement_protection_of_workers_against.7.aspx |journal=Health Physics |language=en-US |volume=99 |issue=1 |pages=66–87 |doi=10.1097/HP.0b013e3181d85908 |pmid=20539126 |bibcode=2010HeaPh..99...66. |issn=0017-9078 |url-access=subscription |access-date=2024-07-30 |archive-date=2024-07-30 |archive-url=https://web.archive.org/web/20240730212719/https://journals.lww.com/health-physics/citation/2010/07000/icnirp_statement_protection_of_workers_against.7.aspx |url-status=live }} Some have suggested that these exposure limits are too conservative and need to be revised for shorter wavelength UV-C.{{Cite journal |last1=Sliney |first1=David H. |last2=Stuck |first2=Bruce E. |date=2021 |title=A Need to Revise Human Exposure Limits for Ultraviolet UV-C Radiation |journal=Photochemistry and Photobiology |volume=97 |issue=3 |pages=485–492 |doi=10.1111/php.13402 |issn=0031-8655 |pmc=8252557 |pmid=33590879}}

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Category:Sterilization (microbiology)

Category:Ultraviolet radiation

Category:Waste treatment technology

Category:Radiobiology