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Home » Overview of peer-reviewed papers on the effect and safety of 222 nm radiation

Overview of peer-reviewed papers on the effect and safety of 222 nm radiation

March 28th 2022

Ushio Care222® Far UV-C Disinfection Technology:
Overview of peer-reviewed studies on the
effect and safety of 222 nm radiation

Table of Contents: 222 nm radiation research

Part I – Effectivity of 222 nm radiation against pathogens

Effect of 222 nm radiation on airborne viruses

Aerosols

  • Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses
    David J. Brenner, et al. Columbia University, USA.
    Key findings: Log-3 reduction of human coronaviruses HCoV229E and beta-HCoVOC43 can be achieved with 1.7 and 1.2 mJ/cm2, respectively. 
    View paper: https://www.nature.com/articles/s41598-020-67211-2.pdf
  • Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases
    David J. Brenner, et al. Columbia University, USA.
    Key findings: A 95% reduction of airborne Influenza virus can be achieved with 2.0 mJ/cm2.
    View paper: https://www.nature.com/articles/s41598-018-21058-w.pdf
  • Predicting airborne coronavirus inactivation by far-UVC in populated rooms using a high-fidelity coupled radiation-CFD model
    Atkinson, et al. Ontario Tech University, Canada.
    Key findings: Modelling shows that the use of far UV-C radiation in addition to ventilation can reduce Coronavirus populations by 50 to 85%.
    View paper: https://www.nature.com/articles/s41598-020-76597-y.pdf

Effect of 222 nm radiation on surface-borne bacteria

Rodents

  • Disinfection and healing effects of 222nm UVC light on methicillin-resistant Staphylococcus aureus infection in mouse wounds
    Nakane, et al. Hirosaki University Hospital, Japan
    Key findings: Irradiation of mouse skin wounds with up to 450 mJ/cm2 reduces MRSA CfUs by log-1.7.
    View paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771808/

  • Germicidal Efficacy and Mammalian Skin Safety of 222-nm UV Light
    David J. Brenner, et al. Columbia University, USA.
    Key findings: 222 nm radiation at 150 mJ/cm2 reduces MRSA by a factor of log-6 without causing skin lesions. 
    View paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552051/

Surfaces and solutions

  • Methicillin-resistant Staphylococcus aureus contamination of hospital-use-only mobile phones and efficacy of 222-nm ultraviolet disinfection
    Hiroki Ohge, et al. Hiroshima University Hospital, Japan.
    Key findings: Exposure of mobiles phones with 15 mJ/cm2 reduced MRSA CFUs by log-4.
    View paper: https://pubmed.ncbi.nlm.nih.gov/33186680/

Effect of 222 nm radiation surface-borne viruses

Surfaces and solutions

  • Pilot study on the decontamination efficacy of an installed 222-nm ultraviolet disinfection device (Care222™), with a motion sensor, in a shared bathroom
    Hiroki Ohge, et al. Hiroshima University Hospital, Japan. 
    Key findings: Care222 significantly reduces CFUs in a test bathroom. 
    View paper: https://www.sciencedirect.com/science/article/pii/S1572100021001605

Part II – Safety concerns

Safety evaluation of 222 nm radiation when applied to skin

Rodents

  • Chronic irradiation with 222-nm UVC light induces neither DNA damage nor epidermal lesions in mouse skin, even at high doses
    Akio Nakane, et al. Hirosaki University, Japan. 
    Key findings: Irradiating murine skin with 450 mJ/cm2 per day, for up to 10 days, produced no CPD cells, indicating that the was skin unharmed. 
    View paper: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201259

  • Evaluation of acute reactions on mouse skin irradiated with 222 and 235 nm UV-C
    Chikako Nishigori, et al. University Kobe, Japan
    Key findings: The minimal perceptible response dose for visible erythema of the mouse skin after 222 nm irradiation is about 15 mJ/cm2. 
    View paper: https://pubmed.ncbi.nlm.nih.gov/33480023/

  • Long-term effects of 222 nm ultraviolet radiation C sterilizing lamps on mice susceptible to ultraviolet radiation
    Chikako Nishigori, et al. University Kobe, Japan.
    Key findings: Mice exposed to doses of up to 4.5 KJ/cm2 in 10 days volunteer showed no signs of irritation or CPD formation, indicating that the skin was unharmed.
    View paper: https://onlinelibrary.wiley.com/doi/epdf/10.1111/php.13269

Humans

  • Exploratory clinical trial on the safety and bactericidal effect of 222-nm ultraviolet C irradiation in healthy humans
    Chikako Nishigori, et al. University Kobe, Japan.
    Key findings: A study of 20 healthy volunteers shows that 222 nm at a dose up to 500 mJ/cm2 does not cause erythema. Bacteria levels decreased at the irradiated site.
    View paper: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0235948

  • Extreme Exposure to Filtered Far-UVC: A Case Study
    Kenneth Wood, et al. Dundee University Hospital, UK.
    Key findings: A study with one volunteer shows that exposure of the human skin with a radiation up to response dose for visible erythema of the mouse skin after 222 nm irradiation is about 18 J/cm2. 
    View paper: https://onlinelibrary.wiley.com/doi/10.1111/php.13385

Importance of filtering 222 nm radiation

  • Exposure of human skin models to KrCl Excimer Lamps: The Impact of Optical Filtering
    David J. Brenner, et al. Columbia University, USA.
    Key findings: Unfiltered radiation from a krypton chloride (KrCl) excimer module induced DNA lesions at 500 mJ/cm2. Filtered radiation did not.
    View paper: https://onlinelibrary.wiley.com/doi/10.1111/php.13383

  • The effect of 222‐nm UVC phototesting on healthy volunteer skin: a pilot study
    Harry Moseley, et al. Dundee University Hospital, UK. 
    Key findings: Unfiltered radiation from a KrCl excimer module induced erythema in 2 healthy volunteers at a level below the expected for a bacteriostatic effect. 
    View paper: https://onlinelibrary.wiley.com/doi/abs/10.1111/phpp.12156

  • Minimal, superficial DNA damage in human skin from filtered far-ultraviolet C
    Ewan Eadie, et al. Dundee University, UK.
    Key findings: Exposure of human skin of a volunteers with 6100 mJ/cm2 shows only minimal CPD formation.
    View paper: https://onlinelibrary.wiley.com/doi/10.1111/php.13383

  • Improved Spectral Purity of 222-nm Irradiation Eliminates Detectable CPD Formation in Skin Reconstructs even at High and Repetitive Disinfecting Doses
    Kamenisch, et al. University Regensburg, Germany.
    Key findings: Human skin model cells irradiated with filtered 222 nm radiation at 3 x 500 mJ/cm2 showed minimal CPD compared to unfiltered radiation.
    View paper: https://onlinelibrary.wiley.com/doi/abs/10.1111/php.13594

Safety evaluation of 222 nm radiation when applied to the eye (corneal damage)

Rodents

  • Re‐evaluation of Rat Corneal Damage by Short‐Wavelength UV Revealed Extremely Less Hazardous Property of Far‐UV‐C
    Masaki Tanito, et al. Shimane University, Japan.
    Key findings: The minimum dose to cause damage in rodent eyes is 5000 mJ/cm2.
    View paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8251618/

Part III – Clinical applications

Medical applications of 222 nm radiation

Clinics

  • Clinical application of 222 nm wavelength ultraviolet C irradiation on SARS CoV-2 contaminated environment
    Chao, et al. School of Medicine, Tzu Chi University, Taiwan.
    Key findings: 48 locations were irradiated with 81 mJ/cm2 of 222 nm radiation. Samples from surfaces were negative for SARS-Covid after 15 seconds of irradiation.
    View paper: https://www.sciencedirect.com/science/article/pii/S1684118221002759

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