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

Narita, Kouji; Asano, Kozo; Naito, Keisuke; Ohashi, Hiroyuki; Sasaki, Masahiro; Morimoto, Yukihiro; Igarashi, Tatsushi; Nakane, Akio

doi:10.1016/j.jhin.2020.03.030

Cited by 146 publications

(107 citation statements)

References 33 publications

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“…In contrast, recent studies have shown that 222-nm UVC is less harmful than 254-nm UVC because far-UVC light has a very limited penetration depth in the skin or eyes and it is also an efficient anti-microbial technology. [9][10][11][12][13] Therefore, a 222-nm UVC disinfection system could be used in occupied public spaces including a hospital room, which is occupied by patients and frequented by health care workers and possibly, visitors. However, further study about the safety and efficacy of 222-nm UVC irradiation in occupied space is needed.…”

Section: Discussionmentioning

confidence: 99%

“…Previous reports demonstrated that 222-nm UVC light, belonging to far-UVC (207-222 nm), has the same highly effective germicidal properties as 254-nm UVC; however, it is less harmful to the skin and eyes than 254-nm UVC because far-UVC light has a very limited penetration depth in the skin or eye. [9][10][11][12][13] In addition, previous studies have reported that low dose of 222-nm UVC inactivated aerosolized H1N1 influenza virus and human coronaviruses alpha HCoV-229E and beta HCoV-OC43. 14,15 Although there are a few reports about the effectiveness of UV disinfection on SARS-CoV-2, 16,17 the effect of 222-nm UVC on SARS-CoV-2 is poorly understood.…”

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confidence: 99%

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Effectiveness of 222-nm ultraviolet light on disinfecting SARS-CoV-2 surface contamination

Kitagawa¹,

Nomura²,

Nazmul³

et al. 2021

American Journal of Infection Control

228

214

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Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), has emerged as a serious threat to human health worldwide. Efficient disinfection of surfaces contaminated with SARS-CoV-2 may help prevent its spread. This study aimed to investigate the in vitro efficacy of 222-nm far-ultraviolet light (UVC) on the disinfection of SARS-CoV-2 surface contamination. Methods: We investigated the titer of SARS-CoV-2 after UV irradiation (0.1 mW/cm 2) at 222 nm for 10-300 seconds using the 50% tissue culture infectious dose (TCID 50). In addition, we used quantitative reverse transcription polymerase chain reaction to quantify SARS-CoV-2 RNA under the same conditions. Results: One and 3 mJ/cm 2 of 222-nm UVC irradiation (0.1 mW/cm 2 for 10 and 30 seconds) resulted in 88.5 and 99.7% reduction of viable SARS-CoV-2 based on the TCID 50 assay, respectively. In contrast, the copy number of SARS-CoV-2 RNA did not change after UVC irradiation even after a 5-minute irradiation. Conclusions: This study shows the efficacy of 222-nm UVC irradiation against SARS-CoV-2 contamination in an in vitro experiment. Further evaluation of the safety and efficacy of 222-nm UVC irradiation in reducing the contamination of real-world surfaces and the potential transmission of SARS-CoV-2 is needed.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Effectiveness of 222-nm ultraviolet light on disinfecting SARS-CoV-2 surface contamination

Kitagawa¹,

Nomura²,

Nazmul³

et al. 2021

American Journal of Infection Control

228

214

View full text Add to dashboard Cite

show abstract

“…The severity of the 2020 COVID-19 pandemic warrants the rapid development and deployment of effective countermeasures to reduce person-to-person transmission. We have developed a promising approach using single-wavelength far-UVC light at 222 nm generated by filtered excimer lamps, which inactivate viruses and bacteria, without inducing biological damage in exposed human cells and tissue [11][12][13][14][15][16]. The approach is based on the biophysically-based principle that far-UVC light, because of its very limited penetration in biological materials, can traverse and kill viruses and bacteria which are typically micrometer dimensions or smaller, but it cannot penetrate even the outer dead-cell layers of human skin, nor the outer tear layer on the surface of the human eye 12 .…”

Section: Discussionmentioning

confidence: 99%

“…By contrast far-UVC light (207 to 222 nm) has been shown to be as efficient as conventional germicidal UV light in killing microorganisms 11 , but it does not have the human health issues associated with conventional germicidal UV light. In short (see below) the reason is that far-UVC has a range in biological materials of only a few micrometers, and thus it cannot reach living human cells in the skin or eyes.…”

Section: Introductionmentioning

confidence: 99%

Far-UVC light efficiently and safely inactivates airborne human coronaviruses

Welch

Shuryak

Brenner

2020

Preprint

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A direct approach to limit airborne transmission of pathogens is to inactivate them within a short time of their production. Germicidal ultraviolet light (UV), typically at 254 nm, is effective in this context, but it is a health hazard to the skin and eyes. By contrast, far-UVC light (207-222 nm) efficiently kills pathogens without harm to exposed human cells or tissues. We previously demonstrated that 222-nm UV light efficiently kills airborne influenza virus (H1N1); here we extend the far-UVC studies to explore efficacy against human coronaviruses from subgroups alpha (HCoV-229E) and beta (HCoV-OC43). We found that low doses of, respectively 1.7 and 1.2 mJ/cm2 inactivated 99.9% of aerosolized alpha coronavirus 229E and beta coronavirus OC43. Based on these results for the beta HCoV-OC43 coronavirus, continuous far-UVC exposure in public locations at the currently recommended exposure limit (3 mJ/cm2/hour) would result in 99.9% viral inactivation in ~ 25 minutes. Increasing the far- UVC intensity by, say, a factor of 2 would halve these disinfection times, while still maintaining safety. As all human coronaviruses have similar genomic size, a key determinant of radiation sensitivity, it is realistic to expect that far-UVC light will show comparable inactivation efficiency against other human coronaviruses, including SARS-CoV-2.

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“…To avoid the above problems related to the human body, many alternative methods have been studied such as inactivation by using cold plasma 19,20 , far-UVC light (200-220 nm region) [21][22][23] , and plasmonic effects 24,25 . However, these methods are still based on high-energy photons or plasma jets, and their effects on the human body have not yet been clarified.…”

mentioning

confidence: 99%

Transient photothermal inactivation of Escherichia coli stained with visible dyes by using a nanosecond pulsed laser

Kohmura

Igami

Tatsuno

et al. 2020

Sci Rep

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Efficient inactivation of Escherichia coli (E. coli) under visible (532 nm) pulsed light irradiation was achieved by fusion of a visible light-absorbing dye with E. coli. Inactivation experiments showed that 3-log inactivation of E. coli was obtained within 20 min under a 50 kJ/cm2 dose. This treatment time and dose magnitude were 10 times faster and 100 times lower, respectively, than the values previously obtained by using a visible femtosecond laser. The mechanism of bacterial death was modeled based on a transient photothermal evaporation effect, where a quantitative evaluation of the temperature increase was given based on the heat transfer equation. As a result of this theoretical analysis, the maximum temperature of the bacteria was correlated with the absorption ratio, pulse energy, and surface-to-volume ratio. An increase in the surface-to-volume ratio with the decreasing size of organic structures leads to the possibility of efficient inactivation of viruses and bacteria under low-dose and non-harmful-visible pulsed light irradiation. Hence, this method can be applied in many fields, such as the instantaneous inactivation of pathogenic viruses and bacteria in a safe and simple manner without damaging large organic structures.

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

Cited by 146 publications

References 33 publications

Effectiveness of 222-nm ultraviolet light on disinfecting SARS-CoV-2 surface contamination

Effectiveness of 222-nm ultraviolet light on disinfecting SARS-CoV-2 surface contamination

Far-UVC light efficiently and safely inactivates airborne human coronaviruses

Transient photothermal inactivation of Escherichia coli stained with visible dyes by using a nanosecond pulsed laser

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