Education

Wavelength

Light is energy and that energy is measured in nanometers on the electromagnetic spectrum. Different Ultraviolet light or “UV” wavelengths (expressed in nanometers or nm) can be used to inactivate the pathogens in the air. The chart below distinguishes ultraviolet light’s different categories in relation to what we can see in the visible spectrum. Traditionally UV-C has been categorized from 200-280nm. The UV-C wavelength 257nm is well known for its germicidal properties and also for being dangerous to humans. But a new type of UV – Far UV is being defined as UV from the ranges of 207nm to 230nm. Since this type of UV is new, science hasn’t given Far UV, its own official category yet. This explains the overlap of ranges in the picture between Far UV and UVC. What makes Far-UV special is that it is being continually proven to be safe for humans. Please refer to our Scientific Study Timeline for more studies.

Despite being new, Far UV is continually being proven to be safe for humans. The basic physics is that FAR UV’s wavelengths cannot penetrate through the outer layer of skin. The above picture illustrates this point and communicates why conventional UV is dangerous to humans. It is well established that UV-C is harmful to humans and as a result, because every unfiltered Far-UV light emits a small UV-C emission, all of our products are filtered.

FLUENCE

Fluence (J/m2)) means exposure dose. Exposure is a unit of time (seconds) and the dose is determined by the irradiance (W/m2) of the light source. Currently there are no regulations determining how much UV exposure an individual is allowed. Manufacturers refer to the “regulatory limit” set by the American Conference of Governmental Industrial Hygienists (ACGIH).

A current study showing Far-UV’s potential against Coronaviruses references those limits. From that study:

In fact there is a regulatory limit as to the amount of 222 nm light to which the public can be exposed, which is 23 mJ/cm2 per 8-hour exposure36,37. Based on our results here for the beta HCoV-OC43 coronavirus, continuous far-UVC exposure at this regulatory limit would result in 90% viral inactivation in approximately 8 minutes, 95% viral inactivation in approximately 11 minutes, 99% inactivation in approximately 16 minutes and 99.9% inactivation in approximately 25 minutes. Thus continuous airborne disinfection with far-UVC light at the currently regulatory limit would provide a major reduction in the ambient level of airborne virus in occupied indoor environments.

These guidelines are important to know as it affects the usability of the light. Another factor to consider that also affects the exposure dose is distance. For instance, two humans sitting in front of a UV source at different distances will get different doses despite being there the same time. To determine the best results, an individual has to calculate how the light will function within the atmosphere it is being placed in.

As a final consideration for this overview is a paper offered by the International Ultraviolet Association. This paper shows FAR-UV’s promise but also addresses liabilities. Our company believes in FAR-UV’s wavelength not just for the current pandemic but in numerous germicidal applications. It’s still important to acknowledge that this technology is still being tested and that each individual has to consider all of this information before purchasing your lights.

https://iuva.org/resources/covid-19/Far%20UV-C%20in%20the%20200%20_%20225%20nm%20range,%20and%20its%20potential%20for%20disinfection%20applications.pdf

Study Shows Ushio’s Care222(R) Lamps Effectively Inactivate SARS-CoV-2 (The COVID-19 Virus)

September 4, 2020

CYPRESS, CA / ACCESSWIRE / September 4, 2020 / ​​​Dr. Hiroki Ohge, Professor, Department of Infectious Diseases, Hiroshima University Hospital, and a group of researchers led…

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Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases

August 20, 2020

Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases Welch, D., Buonanno, M., Grilj, V. et al. Far-UVC light: A new…

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Exploratory clinical trial on the safety and bactericidal effect of 222-nm ultraviolet C irradiation in healthy humans

August 1, 2020

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0235948

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Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses

June 1, 2020

Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses Buonanno, M., Welch, D., Shuryak, I. et al. Far-UVC light (222 nm) efficiently and…

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Repetitive irradiation with 222nm UVC shown to be non-carcinogenic & safe for sterilizing human skin

April 1, 2020

https://www.kobe-u.ac.jp/research_at_kobe_en/NEWS/collaborations/2020_04_07_01.html

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Ultraviolet C light with wavelength of 222 nm inactivates a wide spectrum of microbial pathogens

March 1, 2020

222-nm UVC inactivates a wide spectrum of microbial pathogens Narita, Kouji & Asano, Krisana & Naito, Keisuke & Ohashi, Hiroyuki & Sasaki, Masahiro & Morimoto,…

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Long-term Effects of 222-nm ultraviolet radiation C Sterilizing Lamps on Mice Susceptible to Ultraviolet Radiation

March 1, 2020

Long‐term effects of 222 nm ultraviolet radiation C sterilizing lamps on mice susceptible to ultraviolet radiation Yamano, N., Kunisada, M., Kaidzu, S., Sugihara, K., Nishiaki‐Sawada,…

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DNA Damage Kills Bacterial Spores and Cells Exposed to 222-Nanometer UV Radiation

January 1, 2020

DNA Damage Kills Bacterial Spores and Cells Exposed to 222-Nanometer UV Radiation Willie Taylor, Emily Camilleri, D. Levi Craft, George Korza, Maria Rocha Granados, Jaliyah…

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Evaluation of acute corneal damage induced by 222-nm and 254-nm ultraviolet light in Sprague–Dawley rats

May 1, 2019

Evaluation of acute corneal damage induced by 222-nm and 254-nm ultraviolet light in Sprague–Dawley rats Sachiko Kaidzu, Kazunobu Sugihara, Masahiro Sasaki, Aiko Nishiaki, Tatsushi Igarashi…

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Effect of far ultraviolet light emitted from an optical diffuser on methicillin-resistant Staphylococcus aureus in vitro

August 1, 2018

Effect of far ultraviolet light emitted from an optical diffuser on methicillin-resistant Staphylococcus aureus in vitro Welch D, Buonanno M, Shuryak I, Randers-Pehrson G, Spotnitz…

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Chronic irradiation with 222-nm UVC light induces neither DNA damage nor epidermal lesions in mouse skin, even at high doses

July 1, 2018

Chronic irradiation with 222-nm UVC light induces neither DNA damage nor epidermal lesions in mouse skin, even at high doses Narita K, Asano K, Morimoto…

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February 2017 Germicidal Efficacy and Mammalian Skin Safety of 222-NM UV Light

February 1, 2017

Germicidal Efficacy and Mammalian Skin Safety of 222-nm UV Light Buonanno, M., Ponnaiya, B., Welch, D., Stanislauskas, M., Randers-Pehrson, G., Smilenov, L., Lowy, F. D.,…

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Action spectra for validation of pathogen disinfection in medium-pressure ultraviolet (UV) systems

March 1, 2015

Action spectra for validation of pathogen disinfection in medium-pressure ultraviolet (UV) systems Sara E. Beck, Harold B. Wright, Thomas M. Hargy, Thomas C. Larason, Karl…

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Comparison of the Disinfection Effects of Vacuum‐UV (VUV) and UV Light on Bacillus subtilis Spores in Aqueous Suspensions at 172, 222 and 254 nm

January 1, 2010

Comparison of the Disinfection Effects of Vacuum‐UV (VUV) and UV Light on Bacillus subtilis Spores in Aqueous Suspensions at 172, 222 and 254 nm Wang,…

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August 2006 Higher effectiveness of photoinactivation of bacterial spores, UV resistant vegetative bacteria and mold spores with 222 nm compared to 254 nm wavelength

August 1, 2006

Higher effectiveness of photoinactivation of bacterial spores, UV resistant vegetative bacteria and mold spores with 222 nm compared to 254 nm wavelength Clauß, M. (2006)….

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