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Nishikawa J, Fujii T, Fukuda S, Yoneda S, Tamura Y, Shimizu Y, Yanai A, Kobayashi Y, Harada K, Kawasaki K, Mishima K, Watanabe K, Mizukami Y, Yoshiyama H, Suehiro Y, Yamasaki T, Takami T. Far-ultraviolet irradiation at 222 nm destroys and sterilizes the biofilms formed by periodontitis pathogens. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2024:S1684-1182(24)00082-3. [PMID: 38825404 DOI: 10.1016/j.jmii.2024.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 01/28/2024] [Accepted: 05/19/2024] [Indexed: 06/04/2024]
Abstract
BACKGROUND Periodontal disease is the leading cause of tooth loss, and an association between periodontal disease and non-oral systemic diseases has been shown. Formation of biofilm by periodontal pathogens such as Fusobacterium nucleatum, Porphyromonas gingivalis, and Streptococcus mutans and their resistance to antimicrobial agents are at the root of persistent and chronic bacterial infections. METHODS The bactericidal effect of far-ultraviolet (F-UV) light irradiation at 222 nm on periodontal bacteria was assessed qualitatively and quantitatively. The effect of biofilm disruption by F-UV light on periodontal bacteria was examined by crystal violet staining, and the morphologic changes of the biofilm after F-UV irradiation were explored by confocal laser microscopy and scanning electron microscopy. We developed a thin fiber-type 222 nm F-UV irradiator and studied its safety and effect of reducing bacteria in rodent models. RESULTS F-UV light at 222 nm had a bactericidal effect on F. nucleatum, P. gingivalis, and S. mutans. Irradiation with F-UV light reduced the biofilm formed by the bacteria and sterilized them from within. Confocal laser microscopy showed a clear reduction in biofilm thickness, and scanning electron microscopy confirmed disintegration of the biofilm architecture. F-UV irradiation was less damaging to DNA and less cytotoxic than deep-ultraviolet light, and it reduced bacterial counts on the tooth surface. CONCLUSION F-UV irradiation has the potential to destroy biofilm and act as a bactericide against pathogenic bacteria in the biofilm.
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Affiliation(s)
- Jun Nishikawa
- Faculty of Laboratory Science, Yamaguchi University Graduate School of Medicine, Ube, Japan.
| | - Tomohiro Fujii
- Faculty of Laboratory Science, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Soichiro Fukuda
- Faculty of Laboratory Science, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Shoma Yoneda
- Faculty of Laboratory Science, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Yuta Tamura
- Faculty of Laboratory Science, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Yuki Shimizu
- Faculty of Laboratory Science, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Akie Yanai
- Faculty of Laboratory Science, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Yuki Kobayashi
- Faculty of Laboratory Science, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Koji Harada
- Department of Oral and Maxillofacial Surgery, Yamaguchi University Graduate School of Medicin, Ube, Japan
| | - Keisuke Kawasaki
- Department of Oral and Maxillofacial Surgery, Yamaguchi University Graduate School of Medicin, Ube, Japan
| | - Katsuaki Mishima
- Department of Oral and Maxillofacial Surgery, Yamaguchi University Graduate School of Medicin, Ube, Japan
| | - Kenji Watanabe
- Center for Gene Research, Yamaguchi University, Ube, Japan
| | | | - Hironori Yoshiyama
- Department of Microbiology, Shimane University School of Medicine, Izumo, Japan
| | - Yutaka Suehiro
- Department of Oncology and Laboratory Medicine, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Takahiro Yamasaki
- Department of Oncology and Laboratory Medicine, Yamaguchi University Graduate School of Medicine, Ube, Japan
| | - Taro Takami
- Department of Gastroenterology and Hepatology, Yamaguchi University Graduate School of Medicine, Ube, Japan
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2
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Monika, Madugula SK, Kondabagil K, Kunwar A. Far-UVC (222 nm) irradiation effectively inactivates ssRNA, dsRNA, ssDNA, and dsDNA viruses as compared to germicidal UVC (254 nm). Photochem Photobiol 2024. [PMID: 38736273 DOI: 10.1111/php.13961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/23/2024] [Accepted: 04/24/2024] [Indexed: 05/14/2024]
Abstract
Ultraviolet-C (UVC) irradiation is being used as an effective approach for the disinfection of pathogenic viruses present in air, surfaces, and water. Recently, far-UVC radiation (222 nm) emitted by KrCl* (krypton-chloride) excimer lamps have been recommended for disinfecting high-risk public spaces to reduce the presence and transmission of infectious viruses owing to limited human health exposure risks as compared to germicidal UVC (254 nm). In this study, the UVC inactivation performances of individual filtered KrCl* excimer lamp (222 nm) and germicidal UVC lamp (254 nm) were determined against four viruses, bacteriophages MS2, Phi6, M13, and T4, having different genome compositions (ssRNA, dsRNA, ssDNA and dsDNA, respectively) and shapes (i.e., spherical (Phi6), linear (M13), and icosahedral (MS2 and T4)). Here, the disinfection efficacies of filtered KrCl* excimer lamp (222 nm) and germicidal UVC lamp (254 nm) were evaluated for highly concentrated virus droplets that mimic the virus-laden droplets released from the infected person and deposited on surfaces as fomites. Filtered KrCl* excimer (222 nm) showed significantly better inactivation against all viruses having different genome compositions and structures compared to germicidal UVC (254 nm). The obtained sensitivity against the filtered KrCl* excimer (222 nm) was found to be in the order, T4 > M13 > Phi6 > MS2 whereas for the germicidal UVC (254 nm) it was T4 > M13 > MS2 > Phi6. These results provide a strong basis to promote the use of filtered KrCl* excimer lamps (222 nm) in disinfecting contagious viruses and to limit the associated disease spread in public places and other high-risk areas.
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Affiliation(s)
- Monika
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
| | - Santhosh Kumar Madugula
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
| | - Kiran Kondabagil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
| | - Ambarish Kunwar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
- Koita Centre for Digital Health (KCDH), Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
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3
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Görlitz M, Justen L, Rochette PJ, Buonanno M, Welch D, Kleiman NJ, Eadie E, Kaidzu S, Bradshaw WJ, Javorsky E, Cridland N, Galor A, Guttmann M, Meinke MC, Schleusener J, Jensen P, Söderberg P, Yamano N, Nishigori C, O'Mahoney P, Manstein D, Croft R, Cole C, de Gruijl FR, Forbes PD, Trokel S, Marshall J, Brenner DJ, Sliney D, Esvelt K. Assessing the safety of new germicidal far-UVC technologies. Photochem Photobiol 2024; 100:501-520. [PMID: 37929787 DOI: 10.1111/php.13866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/28/2023] [Accepted: 09/29/2023] [Indexed: 11/07/2023]
Abstract
The COVID-19 pandemic underscored the crucial importance of enhanced indoor air quality control measures to mitigate the spread of respiratory pathogens. Far-UVC is a type of germicidal ultraviolet technology, with wavelengths between 200 and 235 nm, that has emerged as a highly promising approach for indoor air disinfection. Due to its enhanced safety compared to conventional 254 nm upper-room germicidal systems, far-UVC allows for whole-room direct exposure of occupied spaces, potentially offering greater efficacy, since the total room air is constantly treated. While current evidence supports using far-UVC systems within existing guidelines, understanding the upper safety limit is critical to maximizing its effectiveness, particularly for the acute phase of a pandemic or epidemic when greater protection may be needed. This review article summarizes the substantial present knowledge on far-UVC safety regarding skin and eye exposure and highlights research priorities to discern the maximum exposure levels that avoid adverse effects. We advocate for comprehensive safety studies that explore potential mechanisms of harm, generate action spectra for crucial biological effects and conduct high-dose, long-term exposure trials. Such rigorous scientific investigation will be key to determining safe and effective levels for far-UVC deployment in indoor environments, contributing significantly to future pandemic preparedness and response.
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Affiliation(s)
- Maximilian Görlitz
- Massachusetts Institute of Technology, Media Lab, Cambridge, Massachusetts, USA
- SecureBio, Inc., Cambridge, Massachusetts, USA
| | - Lennart Justen
- Massachusetts Institute of Technology, Media Lab, Cambridge, Massachusetts, USA
- SecureBio, Inc., Cambridge, Massachusetts, USA
| | - Patrick J Rochette
- Centre de recherche du CHU de Québec-Université Laval, Axe Médecine Régénératrice Quebec, Quebec City, Quebec, Canada
| | - Manuela Buonanno
- Center for Radiological Research, Columbia University Medical Center, New York City, New York, USA
| | - David Welch
- Center for Radiological Research, Columbia University Medical Center, New York City, New York, USA
| | - Norman J Kleiman
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York City, New York, USA
| | - Ewan Eadie
- Photobiology Unit, Ninewells Hospital, Dundee, UK
| | - Sachiko Kaidzu
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - William J Bradshaw
- Massachusetts Institute of Technology, Media Lab, Cambridge, Massachusetts, USA
- SecureBio, Inc., Cambridge, Massachusetts, USA
| | - Emilia Javorsky
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts, USA
- Future of Life Institute, Cambridge, Massachusetts, USA
| | - Nigel Cridland
- Radiation, Chemicals and Environment Directorate, UK Health Security Agency, Didcot, UK
| | - Anat Galor
- Miami Veterans Affairs Medical Center, University of Miami Health System Bascom Palmer Eye Institute, Miami, Florida, USA
| | | | - Martina C Meinke
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Johannes Schleusener
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Paul Jensen
- Final Approach Inc., Port Orange, Florida, USA
| | - Per Söderberg
- Ophthalmology, Department of Surgical Sciences, Uppsala Universitet, Uppsala, Sweden
| | - Nozomi Yamano
- Division of Dermatology, Department of Internal Related, Kobe University, Kobe, Japan
| | - Chikako Nishigori
- Division of Dermatology, Department of Internal Related, Kobe University, Kobe, Japan
- Japanese Red Cross Hyogo Blood Center, Kobe, Japan
| | - Paul O'Mahoney
- Optical Radiation Effects, UK Health Security Agency, Chilton, UK
| | - Dieter Manstein
- Department of Dermatology, Cutaneous Biology Research Center, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Rodney Croft
- International Commission on Non-Ionizing Radiation Protection (ICNIRP), Chair, Wollongong, New South Wales, Australia
- University of Wollongong, Wollongong, New South Wales, Australia
| | - Curtis Cole
- Sun & Skin Consulting LLC, New Holland, Pennsylvania, USA
| | - Frank R de Gruijl
- Department of Dermatology, Universiteit Leiden, Leiden, South Holland, The Netherlands
| | | | - Stephen Trokel
- Department of Ophthalmology, Columbia University Vagelos College of Physicians and Surgeons, New York City, New York, USA
| | - John Marshall
- Institute of Ophthalmology, University College London, London, UK
| | - David J Brenner
- Center for Radiological Research, Columbia University Medical Center, New York City, New York, USA
| | - David Sliney
- IES Photobiology Committee, Chair, Fallston, Maryland, USA
- Consulting Medical Physicist, Fallston, Maryland, USA
| | - Kevin Esvelt
- Massachusetts Institute of Technology, Media Lab, Cambridge, Massachusetts, USA
- SecureBio, Inc., Cambridge, Massachusetts, USA
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Buonanno M, Kleiman NJ, Welch D, Hashmi R, Shuryak I, Brenner DJ. 222 nm far-UVC light markedly reduces the level of infectious airborne virus in an occupied room. Sci Rep 2024; 14:6722. [PMID: 38509265 PMCID: PMC10954628 DOI: 10.1038/s41598-024-57441-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 03/18/2024] [Indexed: 03/22/2024] Open
Abstract
An emerging intervention for control of airborne-mediated pandemics and epidemics is whole-room far-UVC (200-235 nm). Laboratory studies have shown that 222-nm light inactivates airborne pathogens, potentially without harm to exposed occupants. While encouraging results have been reported in benchtop studies and in room-sized bioaerosol chambers, there is a need for quantitative studies of airborne pathogen reduction in occupied rooms. We quantified far-UVC mediated reduction of aerosolized murine norovirus (MNV) in an occupied mouse-cage cleaning room within an animal-care facility. Benchtop studies suggest that MNV is a conservative surrogate for airborne viruses such as influenza and coronavirus. Using four 222-nm fixtures installed in the ceiling, and staying well within current recommended regulatory limits, far-UVC reduced airborne infectious MNV by 99.8% (95% CI: 98.2-99.9%). Similar to previous room-sized bioaerosol chamber studies on far-UVC efficacy, these results suggest that aerosolized virus susceptibility is significantly higher in room-scale tests than in bench-scale laboratory studies. That said, as opposed to controlled laboratory studies, uncertainties in this study related to airflow patterns, virus residence time, and dose to the collected virus introduce uncertainty into the inactivation estimates. This study is the first to directly demonstrate far-UVC anti-microbial efficacy against airborne pathogens in an occupied indoor location.
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Affiliation(s)
- Manuela Buonanno
- Center for Radiological Research, Columbia University Irving Medical Center, 630 West 168th St., New York, NY, 10032, USA.
| | - Norman J Kleiman
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Irving Medical Center, New York, NY, USA
| | - David Welch
- Center for Radiological Research, Columbia University Irving Medical Center, 630 West 168th St., New York, NY, 10032, USA
| | - Raabia Hashmi
- Center for Radiological Research, Columbia University Irving Medical Center, 630 West 168th St., New York, NY, 10032, USA
| | - Igor Shuryak
- Center for Radiological Research, Columbia University Irving Medical Center, 630 West 168th St., New York, NY, 10032, USA
| | - David J Brenner
- Center for Radiological Research, Columbia University Irving Medical Center, 630 West 168th St., New York, NY, 10032, USA.
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5
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Kousha O, O'Mahoney P, Hammond R, Wood K, Eadie E. 222 nm Far-UVC from filtered Krypton-Chloride excimer lamps does not cause eye irritation when deployed in a simulated office environment. Photochem Photobiol 2024; 100:137-145. [PMID: 37029739 PMCID: PMC10952573 DOI: 10.1111/php.13805] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/17/2023] [Accepted: 03/20/2023] [Indexed: 04/09/2023]
Abstract
Far-UVC, from filtered Krypton-Chloride lamps, is promising for reducing airborne transmission of disease. While significant research has been undertaken to investigate skin safety of these lamps, less work has been undertaken on eye safety. There is limited data on human eye safety or discomfort from the deployment of this germicidal technology. In this pilot study, immediate and delayed eye discomfort were assessed in a simulated office environment with deployment of Krypton-Chloride lamps, located on the ceiling and directed downwards into the occupied room. Discomfort was assessed immediately postexposure and several days after exposure using validated, Standard Patient Evaluation Eye Dryness (SPEED) and Ocular Surface Disease Index (OSDI) questionnaires. Our results show no significant eye discomfort or adverse effects from the deployment of Far-UVC in this simulated office environment, even when lamps were operated continuously with participants receiving head exposures of up to 50 mJ cm-2 . In addition, a statistically significant reduction in bacteria and fungi of 52% was observed. Far-UVC in this simulated office environment did not cause any clinically significant eye discomfort and was effective at reducing pathogens in the room. These results contribute an important step to further investigation of the interaction of Far-UVC with the human eye.
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Affiliation(s)
- Obaid Kousha
- School of MedicineUniversity of St AndrewsSt AndrewsUK
| | | | | | - Kenneth Wood
- SUPA, School of Physics and AstronomyUniversity of St AndrewsSt AndrewsUK
| | - Ewan Eadie
- Photobiology Unit, NHS TaysideNinewells Hospital and Medical SchoolDundeeUK
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6
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Wang Y, Ma B, Zhao J, Tang Z, Li W, He C, Xia D, Linden KG, Yin R. Rapid Inactivation of Fungal Spores in Drinking Water by Far-UVC Photolysis of Free Chlorine. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:21876-21887. [PMID: 37978925 DOI: 10.1021/acs.est.3c05703] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Effective and affordable disinfection technology is one key to achieving Sustainable Development Goal 6. In this work, we develop a process by integrating Far-UVC irradiation at 222 nm with free chlorine (UV222/chlorine) for rapid inactivation of the chlorine-resistant and opportunistic Aspergillus niger spores in drinking water. The UV222/chlorine process achieves a 5.0-log inactivation of the A. niger spores at a chlorine dosage of 3.0 mg L-1 and a UV fluence of 30 mJ cm-2 in deionized water, tap water, and surface water. The inactivation rate constant of the spores by the UV222/chlorine process is 0.55 min-1, which is 4.6-fold, 5.5-fold, and 1.8-fold, respectively, higher than those of the UV222 alone, chlorination alone, and the conventional UV254/chlorine process under comparable conditions. The more efficient inactivation by the UV222/chlorine process is mainly attributed to the enhanced generation of reactive chlorine species (e.g., 6.7 × 10-15 M of Cl•) instead of hydroxyl radicals from UV222 photolysis of chlorine, which is verified through both experiments and a kinetic model. We further demonstrate that UV222 photolysis damages the membrane integrity and benefits the penetration of chlorine and radicals into cells for inactivation. The merits of the UV222/chlorine process over the UV254/chlorine process also include the more effective inhibition of the photoreactivation of the spores after disinfection and the lower formation of chlorinated disinfection byproducts and toxicity.
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Affiliation(s)
- Yongyi Wang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong
| | - Ben Ma
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Jing Zhao
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong
| | - Zhuoyun Tang
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Wanxin Li
- Department of Health and Environmental Sciences, Xi'an Jiaotong-Liverpool University, Suzhou 215000, China
| | - Chun He
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Dehua Xia
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Karl G Linden
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Ran Yin
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong
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Seyedi S, Ma B, Groves M, King H, Linden KG. Field Study and Evaluation of KrCl* Far UV-C Device Capability for Inactivation of Phi6 Bacteriophage. Photochem Photobiol 2023; 99:1293-1298. [PMID: 36533876 DOI: 10.1111/php.13767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
"Far UV-C" is an effective disinfection method that can be deployed in occupied areas. Commercially available Krypton Chloride (KrCl*) excimer lamps filtered to emit at 222 nm are effective in disinfecting pathogens and safe for human exposure up to an allowable threshold exposure, which is much longer than for conventional UV lamps emitting at 254 nm. Laboratory and controlled field testing of a filtered KrCl* excimer lamp for disinfection of a virus suspended in a thin film aqueous solution in an occupied office setting was conducted. Complete inactivation of almost 6 log (99.9999%) of Phi6 bacteriophage virus was achieved in ~20 min of exposure time in a field setting, equivalent to a dose of about 10 mJ cm-2 . The Phi6 inactivation rate constant for the field test results were not statistically different from laboratory values (P > 0.05, paired t-test). When positioned at 1 m distance from possible human exposure, this device can be used safely for almost 4.5 h of continuous direct exposure without any acute or long-term adverse health effects. This study illustrates the applicability and deployment of Far UV-C for pathogen reduction and can help in decision making for implementation of Far UV-C for disinfection in human-occupied environments.
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Affiliation(s)
- Saba Seyedi
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, CO
- Hazen and Sawyer, Fairfax, VA
| | - Ben Ma
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, CO
| | - Megan Groves
- Population Lights, Inc. d/b/a Population, San Francisco, CA
| | - Hal King
- Public Health Innovations, Saint Simons Island, GA
| | - Karl G Linden
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, CO
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Truong CS, Muthukutty P, Jang HK, Kim YH, Lee DH, Yoo SY. Filter-Free, Harmless, and Single-Wavelength Far UV-C Germicidal Light for Reducing Airborne Pathogenic Viral Infection. Viruses 2023; 15:1463. [PMID: 37515151 PMCID: PMC10385069 DOI: 10.3390/v15071463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/22/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
Germicidal lamps that primarily emit 254 nm ultraviolet (UV) radiation have been effectively utilized for surface sterilization, but they cannot be used on human skin and eyes due to their harmful and genotoxic activity. Recent reports have shown that far UV-C light (207-222 nm) can efficiently kill pathogens with potentially no harm to exposed human tissues. However, these methods still require additional filtering and/or further protective equipment. In this study, we demonstrate a filter-free, harmless, and single-wavelength far UV-C 207 nm germicidal light source that can be used to inactivate different respiratory viruses. It can be exploited as a safe and effective disinfection tool for various airborne viruses. We successfully developed a single-wavelength far UV-C source that produces an exact wavelength of 207 nm. We examined its safety on human skin and corneal cell lines, as well as its effects on inactivating different airborne viruses, such as coronavirus, adenovirus, and vaccinia virus. We expect that our far UV-C lamps can be safely and conveniently used to reduce COVID-19 infections and protect both our living spaces and hospitals from the threat of contamination by possible new or mutant viruses.
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Affiliation(s)
- Cao-Sang Truong
- BIO-IT Foundry Technology Institute, Pusan National University, Busan 46241, Republic of Korea
| | - Palaniyandi Muthukutty
- BIO-IT Foundry Technology Institute, Pusan National University, Busan 46241, Republic of Korea
| | - Ho Kyung Jang
- SUNJE HI TEK Co., Ltd., Busan 46047, Republic of Korea
| | - Young-Ho Kim
- Department of Molecular Biology and Immunology, College of Medicine, Kosin University, Busan 49267, Republic of Korea
| | - Dong Hoon Lee
- SUNJE HI TEK Co., Ltd., Busan 46047, Republic of Korea
| | - So Young Yoo
- BIO-IT Foundry Technology Institute, Pusan National University, Busan 46241, Republic of Korea
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9
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Ma B, Burke-Bevis S, Tiefel L, Rosen J, Feeney B, Linden KG. Reflection of UVC wavelengths from common materials during surface UV disinfection: Assessment of human UV exposure and ozone generation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 869:161848. [PMID: 36709900 DOI: 10.1016/j.scitotenv.2023.161848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/22/2023] [Accepted: 01/22/2023] [Indexed: 06/18/2023]
Abstract
The COVID-19 pandemic has promoted interest in using devices emitting ultraviolet-C (UVC) irradiation (200-280 nm) for surface disinfection to reduce pathogen transmission, especially in occupied public spaces. While UVC devices have been shown to be highly effective against various pathogens, there are safety concerns when using conventional UVC devices for surface disinfection, including human exposure of reflected UVC irradiation and ozone generation. Emerging Far UVC devices (emitting at 200-230 nm), like the krypton chloride (KrCl*) excimer, have the potential to be safely applied in occupied spaces due to their minimal adverse effects on skin and eyes. In this study, UV reflection of 21 common materials was documented and compared using a filtered KrCl* excimer (installed with a bandpass filter at 222 nm), an unfiltered KrCl* excimer, and a conventional low-pressure mercury vapor lamp. The safety of Far UVC devices was evaluated based on the irradiance and spectrum of reflected UV irradiation and ozone generation measured at various locations around the device. Our results show that most common materials can reflect UV irradiation, among which some metals tend to have greater reflection. The Far UVC devices, especially the filtered KrCl* excimer, should be safe to be applied in occupied spaces for effective surface disinfection, with limited ozone generation and no health risk from reflected UV irradiation. However more caution is needed when using unfiltered KrCl* devices and conventional UV 254 nm light. This study provides urgently needed data on UV reflection of common materials and guidance for safety assessments of UVC devices for surface disinfection in occupied spaces.
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Affiliation(s)
- Ben Ma
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, 4001 Discovery Dr., Boulder, CO 80303, United States
| | - Sam Burke-Bevis
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, 4001 Discovery Dr., Boulder, CO 80303, United States
| | - Luke Tiefel
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, 4001 Discovery Dr., Boulder, CO 80303, United States
| | - Jennifer Rosen
- Freestyle Partners, LLC, and its affiliate, FSP Innovations, LLC, MI, United States
| | - Ben Feeney
- Freestyle Partners, LLC, and its affiliate, FSP Innovations, LLC, MI, United States
| | - Karl G Linden
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, 4001 Discovery Dr., Boulder, CO 80303, United States.
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Tavares RSN, Adamoski D, Girasole A, Lima EN, da Silva Justo-Junior A, Domingues R, Silveira ACC, Marques RE, de Carvalho M, Ambrosio ALB, Leme AFP, Dias SMG. Different biological effects of exposure to far-UVC (222 nm) and near-UVC (254 nm) irradiation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2023; 243:112713. [PMID: 37086566 DOI: 10.1016/j.jphotobiol.2023.112713] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/18/2023] [Accepted: 04/10/2023] [Indexed: 04/24/2023]
Abstract
Ultraviolet C (UVC) light has long been used as a sterilizing agent, primarily through devices that emit at 254 nm. Depending on the dose and duration of exposure, UV 254 nm can cause erythema and photokeratitis and potentially cause skin cancer since it directly modifies nitrogenated nucleic acid bases. Filtered KrCl excimer lamps (emitting mainly at 222 nm) have emerged as safer germicidal tools and have even been proposed as devices to sterilize surgical wounds. All the studies that showed the safety of 222 nm analyzed cell number and viability, erythema generation, epidermal thickening, the formation of genetic lesions such as cyclobutane pyrimidine dimers (CPDs) and pyrimidine-(6-4)-pyrimidone photoproducts (6-4PPs) and cancer-inducing potential. Although nucleic acids can absorb and be modified by both UV 254 nm and UV 222 nm equally, compared to UV 254 nm, UV 222 nm is more intensely absorbed by proteins (especially aromatic side chains), causing photooxidation and cross-linking. Here, in addition to analyzing DNA lesion formation, for the first time, we evaluated changes in the proteome and cellular pathways, reactive oxygen species formation, and metalloproteinase (MMP) levels and activity in full-thickness in vitro reconstructed human skin (RHS) exposed to UV 222 nm. We also performed the longest (40 days) in vivo study of UV 222 nm exposure in the HRS/J mouse model at the occupational threshold limit value (TLV) for indirect exposure (25 mJ/cm2) and evaluated overall skin morphology, cellular pathological alterations, CPD and 6-4PP formation and MMP-9 activity. Our study showed that processes related to reactive oxygen species and inflammatory responses were more altered by UV 254 nm than by UV 222 nm. Our chronic in vivo exposure assay using the TLV confirmed that UV 222 nm causes minor damage to the skin. However, alterations in pathways related to skin regeneration raise concerns about direct exposure to UV 222 nm.
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Affiliation(s)
- Renata Spagolla Napoleão Tavares
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Douglas Adamoski
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Alessandra Girasole
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Ellen Nogueira Lima
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Amauri da Silva Justo-Junior
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Romênia Domingues
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Ana Clara Caznok Silveira
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Rafael Elias Marques
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Murilo de Carvalho
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil; Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Andre Luis Berteli Ambrosio
- Sao Carlos Institute of Physics (IFSC), University of Sao Paulo (USP), Sao Carlos, Zip Code 13563-1203, SP, Brazil
| | - Adriana Franco Paes Leme
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil
| | - Sandra Martha Gomes Dias
- Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Zip Code 13083-970, Campinas, Sao Paulo, Brazil.
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11
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Lu YH, Wu H, Zhang HH, Li WS, Lai ACK. Synergistic disinfection of aerosolized bacteria and bacteriophage by far-UVC (222-nm) and negative air ions. JOURNAL OF HAZARDOUS MATERIALS 2023; 441:129876. [PMID: 36087531 DOI: 10.1016/j.jhazmat.2022.129876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/22/2022] [Accepted: 08/28/2022] [Indexed: 06/15/2023]
Abstract
Air ionizers and 222-nm krypton-chlorine (KrCl) excilamp have proven to be effective disinfection apparatus for bacteria and viruses with limited health risks. We determined inactivation efficiencies by operating them individually and in combined modules. Gram-positive and gram-negative bacteria, non-enveloped dsDNA virus, and enveloped dsRNA virus were examined in a designed air disinfection system. Our results showed that the bioaerosols were inactivated efficiently by negative ionizers and far-UVC (222-nm), either used individually or in combination. Among which the combined modules of negative ionizers and KrCl excilamp had the best disinfection performance for the bacteria. The aerosolized virus P22 and Phi 6 were more susceptible to 222-nm emitted by KrCl excilamp than negative air ions. Significant greater inactivation of bacterial bioaerosols were identified after treated by combined treatment of negative air ion and far-UVC for 2 minutes (Escherichia coli, 6.25 natural log (ln) reduction; Staphylococcus epidermidis, 3.66 ln reduction), as compared to the mean sum value of inactivation results by respective individual treatment of negative ionizers and KrCl excilamp (Escherichia coli, 4.34 ln; Staphylococcus epidermidis, 1.75 ln), indicating a synergistic inactivation effect. The findings provide important baseline data to support the design and development of safe and high-efficient disinfection systems.
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Affiliation(s)
- Y H Lu
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong China
| | - H Wu
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong China; Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong China
| | - H H Zhang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong China
| | - W S Li
- School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong China
| | - A C K Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong China.
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12
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Yoshiyama KO, Okamoto NL, Hidema J, Higashitani A. 222 nm far-UVC efficiently introduces nerve damage in Caenorhabditis elegans. PLoS One 2023; 18:e0281162. [PMID: 36719882 PMCID: PMC9888708 DOI: 10.1371/journal.pone.0281162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 01/16/2023] [Indexed: 02/01/2023] Open
Abstract
Far-ultraviolet radiation C light (far-UVC; 222 nm wavelength) has received attention as a safer light for killing pathogenic bacteria and viruses, as no or little DNA damage is observed after irradiation in mammalian skin models. Far-UVC does not penetrate deeply into tissues; therefore, it cannot reach the underlying critical basal cells. However, it was unclear whether far-UVC (222-UVC) irradiation could cause more biological damage at shallower depths than the 254 nm UVC irradiation (254-UVC), which penetrates more deeply. This study investigated the biological effects of 222- and 254-UVC on the small and transparent model organism Caenorhabditis elegans. At the same energy level of irradiation, 222-UVC introduced slightly less cyclobutane pyrimidine dimer damage to naked DNA in solution than 254-UVC. The survival of eggs laid during 0-4 h after irradiation showed a marked decrease with 254-UVC but not 222-UVC. In addition, defect of chromosomal condensation was observed in a full-grown oocyte by 254-UVC irradiation. In contrast, 222-UVC had a significant effect on the loss of motility of C. elegans. The sensory nervous system, which includes dopamine CEP and PVD neurons on the body surface, was severely damaged by 222-UVC, but not by the same dose of 254-UVC. Interestingly, increasing 254-UVC irradiation by about 10-fold causes similar damage to CEP neurons. These results suggest that 222-UVC is less penetrating, so energy transfer occurs more effectively in tissues near the surface, causing more severe damage than 254-UVC.
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Affiliation(s)
| | | | - Jun Hidema
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
- Division for the Establishment of Frontier Sciences of the Organization for Advanced Studies, Tohoku University, Sendai, Japan
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Welch D, Kleiman NJ, Arden PC, Kuryla CL, Buonanno M, Ponnaiya B, Wu X, Brenner DJ. No Evidence of Induced Skin Cancer or Other Skin Abnormalities after Long-Term (66 week) Chronic Exposure to 222-nm Far-UVC Radiation. Photochem Photobiol 2023; 99:168-175. [PMID: 35614842 PMCID: PMC9691791 DOI: 10.1111/php.13656] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/23/2022] [Indexed: 01/25/2023]
Abstract
Far-UVC radiation, typically defined as 200-235 nm, has similar or greater anti-microbial efficacy compared with conventional 254-nm germicidal radiation. In addition, biophysical considerations of the interaction of far-UVC with tissue, as well as multiple short-term safety studies in animal models and humans, suggest that far-UVC exposure may be safe for skin and eye tissue. Nevertheless, the potential for skin cancer after chronic long-term exposure to far-UVC has not been studied. Here, we assessed far-UVC induced carcinogenic skin changes and other pathological dermal abnormalities in 96 SKH-1 hairless mice of both sexes that were exposed to average daily dorsal skin doses of 400, 130 or 55 mJ cm-2 of 222 nm far-UVC radiation for 66 weeks, 5 days per week, 8 h per day, as well as similarly-treated unexposed controls. No evidence for increased skin cancer, abnormal skin growths or incidental skin pathology findings was observed in the far-UVC-exposed mice. In addition, there were no significant changes in morbidity or mortality. The findings from this study support the long-term safety of long-term chronic exposure to far-UVC radiation, and therefore its potential suitability as a practical anti-microbial approach to reduce airborne viral and bacterial loads in occupied indoor settings.
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Affiliation(s)
- David Welch
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY,Corresponding author: (David Welch)
| | - Norman J. Kleiman
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Irving Medical Center, New York, NY
| | - Peter C. Arden
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Irving Medical Center, New York, NY
| | - Christine L. Kuryla
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Irving Medical Center, New York, NY
| | - Manuela Buonanno
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY
| | - Brian Ponnaiya
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY
| | - Xuefeng Wu
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY
| | - David J. Brenner
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY
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Kaidzu S, Sugihara K, Sasaki M, Nishiaki A, Ohashi H, Igarashi T, Tanito M. Safety Evaluation of Far-UV-C Irradiation to Epithelial Basal Cells in the Corneal Limbus. Photochem Photobiol 2022. [PMID: 36437576 DOI: 10.1111/php.13750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 11/15/2022] [Indexed: 11/29/2022]
Abstract
Basal cells in the corneal limbus play an important role in the turnover cycle because they are the source of all cells that constitute the corneal epithelium. We examined the penetration depth of ultraviolet (UV) light in the corneal limbus and assessed the safety of Far-UV-C on stem cells in the basal area of the corneal limbus. Rats were irradiated with UV at peaks of 207, 222, 235, 254 and 311 nm while under anesthesia. The UV penetration depth in the rat corneal limbal epithelium was wavelength dependent: 311 nm UV-B and 254 nm UV-C reached the basal cells of the epithelium, and 235 nm radiation reached the middle area; however, 207 and 222 nm UV-C reached only the superficial layer of the epithelium. Porcine cornea, which is similar to the human eye in size and structure, were irradiated with 222 and 254 nm UV-C. As in rats, 222 nm UV-C reached only the superficial layer of the porcine corneal limbal epithelium. These results indicate that Far-UV-C, such as radiation of wavelengths of 207 and 222 nm, could not reach corneal epithelial stem cells, i.e. the cells remained intact. It is unlikely that the turnover of the corneal epithelium is obstructed or disrupted by exposure to Far-UV-C.
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Affiliation(s)
- Sachiko Kaidzu
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Kazunobu Sugihara
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | | | | | | | | | - Masaki Tanito
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
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15
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Abkar L, Zimmermann K, Dixit F, Kheyrandish A, Mohseni M. COVID-19 pandemic lesson learned- critical parameters and research needs for UVC inactivation of viral aerosols. JOURNAL OF HAZARDOUS MATERIALS ADVANCES 2022; 8:100183. [PMID: 36619826 PMCID: PMC9553962 DOI: 10.1016/j.hazadv.2022.100183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/28/2022] [Accepted: 10/10/2022] [Indexed: 11/28/2022]
Abstract
The COVID-19 pandemic highlighted public awareness of airborne disease transmission in indoor settings and emphasized the need for reliable air disinfection technologies. This increased awareness will carry in the post-pandemic era along with the ever-emerging SARS-CoV variants, necessitating effective and well-defined protocols, methods, and devices for air disinfection. Ultraviolet (UV)-based air disinfection demonstrated promising results in inactivating viral bioaerosols. However, the reported data diversity on the required UVC doses has hindered determining the best UVC practices and led to confusion among the public and regulators. This article reviews available information on critical parameters influencing the efficacy of a UVC air disinfection system and, consequently, the required dose including the system's components as well as operational and environmental factors. There is a consensus in the literature that the interrelation of humidity and air temperature has a significant impact on the UVC susceptibility, which translate to changing the UVC efficacy of commercialized devices in indoor settings under varying conditions. Sampling and aerosolization techniques reported to have major influence on the result interpretation and it is recommended to use several sampling methods simultaneously to generate comparable and conclusive data. We also considered the safety concerns and the potential safe alternative of UVC, far-UVC. Finally, the gaps in each critical parameter and the future research needs of the field are represented. This paper is the first step to consolidating literature towards developing a standard validation protocol for UVC air disinfection devices which is determined as the one of the research needs.
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Key Words
- Aerosolization of pathogens
- Air sampling methods
- Airborne transmission
- CDC, centre for disease control and prevention (USA)
- CMD, count median diameter
- DNA, deoxyribonucleic acid
- DSB, double strand break
- Far-UVC
- Far-UVC, ultraviolet irradiation in the ‘far’ range of 200–230 nm
- GTC, growth tube collectors
- LED, light emitting diode
- LPUV, low-pressure ultraviolet lamp
- NIOSH, national institute for occupational safety and health
- PBS, phosphate buffered saline
- PRRS, porcine reproductive and respiratory syndrome
- Particle size distribution
- REL, recommended exposure limit
- RH, relative humidity
- RNA, ribonucleic acid
- ROS, reactive oxygen species
- SARS-CoV-2, severe acute respiratory syndrome coronavirus-2
- SSB, single strand break
- Suspending media
- UV, ultraviolet irradiation
- UV-LED, light emitting diode in the ultraviolet range
- UVC, ultraviolet irradiation in the ‘C’, or germicidal, spectrum from 200 to 290 nm
- UVGI, ultraviolet germicidal irradiation
- Viral UVC susceptibility
- dsDNA, double-stranded deoxyribonucleic acid
- ssRNA, single-stranded ribonucleic acid
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16
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Sugihara K, Kaidzu S, Sasaki M, Ichioka S, Takayanagi Y, Shimizu H, Sano I, Hara K, Tanito M. One-Year Ocular Safety Observation of Workers and Estimations of Microorganism Inactivation Efficacy in the Room Irradiated with 222-Nm far Ultraviolet-C Lamps. Photochem Photobiol 2022; 99:967-974. [PMID: 36081379 DOI: 10.1111/php.13710] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/05/2022] [Indexed: 11/30/2022]
Abstract
Two krypton-chloride germicidal excimer lamp units (Care222 TRT-104C11-UI-U3, USHIO Inc.) were installed in the examination room of an ophthalmology department. The irradiation dose was set not to exceed the former (i.e., before 2022) threshold limit value (TLV) (22 mJ/cm2 /8 hours) recommended by the ACGIH. Section 1: The eyes and lids of the 6 ophthalmologists (5 wore glasses for myopic correction) who worked in the room for a mean stay of 6.7 hours/week were prospectively observed for 12 months. Slitlamp examinations revealed neither acute adverse events such as corneal erosion, conjunctival hyperemia, lid skin erythema nor chronic adverse events such as pterygium, cataract, or lid tumor. The visual acuity, refractive error, corneal endothelial cell density remained unchanged during the study. Section 2: The irradiation of samples placed on the table or floor using the same fixtures in the room (5-7.5 mJ/cm2 ) was associated with >99% inhibition of φX174 phage and >90% inhibition of S. aureus. In conclusion, no acute or chronic health effects in human participants was observed in a clinical setting of full-room ultraviolet germicidal irradiation by 222-nm lamp units and high efficacy in deactivation of microorganisms was determined in the same setting.
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Affiliation(s)
- Kazunobu Sugihara
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Sachiko Kaidzu
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | | | - Sho Ichioka
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Yuji Takayanagi
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Hiroshi Shimizu
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Ichiya Sano
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Katsunori Hara
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Masaki Tanito
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
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17
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Inactivation Rates for Airborne Human Coronavirus by Low Doses of 222 nm Far-UVC Radiation. Viruses 2022; 14:v14040684. [PMID: 35458414 PMCID: PMC9030991 DOI: 10.3390/v14040684] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/23/2022] [Accepted: 03/23/2022] [Indexed: 12/22/2022] Open
Abstract
Recent research using UV radiation with wavelengths in the 200–235 nm range, often referred to as far-UVC, suggests that the minimal health hazard associated with these wavelengths will allow direct use of far-UVC radiation within occupied indoor spaces to provide continuous disinfection. Earlier experimental studies estimated the susceptibility of airborne human coronavirus OC43 exposed to 222-nm radiation based on fitting an exponential dose–response curve to the data. The current study extends the results to a wider range of doses of 222 nm far-UVC radiation and uses a computational model coupling radiation transport and computational fluid dynamics to improve dosimetry estimates. The new results suggest that the inactivation of human coronavirus OC43 within our exposure system is better described using a bi-exponential dose–response relation, and the estimated susceptibility constant at low doses—the relevant parameter for realistic low dose rate exposures—was 12.4 ± 0.4 cm2/mJ, which described the behavior of 99.7% ± 0.05% of the virus population. This new estimate is more than double the earlier susceptibility constant estimates that were based on a single-exponential dose response. These new results offer further evidence as to the efficacy of far-UVC to inactivate airborne pathogens.
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18
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Eadie E, Hiwar W, Fletcher L, Tidswell E, O'Mahoney P, Buonanno M, Welch D, Adamson CS, Brenner DJ, Noakes C, Wood K. Far-UVC (222 nm) efficiently inactivates an airborne pathogen in a room-sized chamber. Sci Rep 2022; 12:4373. [PMID: 35322064 PMCID: PMC8943125 DOI: 10.1038/s41598-022-08462-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 03/07/2022] [Indexed: 12/04/2022] Open
Abstract
Many infectious diseases, including COVID-19, are transmitted by airborne pathogens. There is a need for effective environmental control measures which, ideally, are not reliant on human behaviour. One potential solution is Krypton Chloride (KrCl) excimer lamps (often referred to as Far-UVC), which can efficiently inactivate pathogens, such as coronaviruses and influenza, in air. Research demonstrates that when KrCl lamps are filtered to remove longer-wavelength ultraviolet emissions they do not induce acute reactions in the skin or eyes, nor delayed effects such as skin cancer. While there is laboratory evidence for Far-UVC efficacy, there is limited evidence in full-sized rooms. For the first time, we show that Far-UVC deployed in a room-sized chamber effectively inactivates aerosolised Staphylococcus aureus. At a room ventilation rate of 3 air-changes-per-hour (ACH), with 5 filtered-sources the steady-state pathogen load was reduced by 98.4% providing an additional 184 equivalent air changes (eACH). This reduction was achieved using Far-UVC irradiances consistent with current American Conference of Governmental Industrial Hygienists threshold limit values for skin for a continuous 8-h exposure. Our data indicate that Far-UVC is likely to be more effective against common airborne viruses, including SARS-CoV-2, than bacteria and should thus be an effective and "hands-off" technology to reduce airborne disease transmission. The findings provide room-scale data to support the design and development of effective Far-UVC systems.
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Affiliation(s)
- Ewan Eadie
- NHS Tayside, Photobiology Unit, Ninewells Hospital and Medical School, Dundee, DD1 9SY, UK.
| | - Waseem Hiwar
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Louise Fletcher
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Emma Tidswell
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Paul O'Mahoney
- NHS Tayside, Photobiology Unit, Ninewells Hospital and Medical School, Dundee, DD1 9SY, UK
- School of Medicine Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK
| | - Manuela Buonanno
- Center for Radiological Research, Columbia University Medical Center, New York, NY, USA
| | - David Welch
- Center for Radiological Research, Columbia University Medical Center, New York, NY, USA
| | - Catherine S Adamson
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, KY16 9ST, UK
| | - David J Brenner
- Center for Radiological Research, Columbia University Medical Center, New York, NY, USA
| | - Catherine Noakes
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Kenneth Wood
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
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Mariita RM, Davis JH, Randive RV. Illuminating Human Norovirus: A Perspective on Disinfection of Water and Surfaces Using UVC, Norovirus Model Organisms, and Radiation Safety Considerations. Pathogens 2022; 11:pathogens11020226. [PMID: 35215169 PMCID: PMC8879714 DOI: 10.3390/pathogens11020226] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/22/2022] [Accepted: 02/03/2022] [Indexed: 02/04/2023] Open
Abstract
Human noroviruses (HuNoVs) are a major cause of gastroenteritis and are associated with high morbidity because of their ability to survive in the environment and small inoculum size required for infection. Norovirus is transmitted through water, food, high touch-surfaces, and human-to-human contact. Ultraviolet Subtype C (UVC) light-emitting diodes (LEDs) can disrupt the norovirus transmission chain for water, food, and surfaces. Here, we illuminate considerations to be adhered to when picking norovirus surrogates for disinfection studies and shine light on effective use of UVC for norovirus infection control in water and air and validation for such systems and explore the blind spot of radiation safety considerations when using UVC disinfection strategies. This perspective also discusses the promise of UVC for norovirus mitigation to save and ease life.
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20
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Welch D, Aquino de Muro M, Buonanno M, Brenner DJ. Wavelength-dependent DNA Photodamage in a 3-D Human Skin Model over the far-UVC and Germicidal-UVC Wavelength Ranges from 215 to 255 nm. Photochem Photobiol 2022; 98:1167-1171. [PMID: 35104367 PMCID: PMC9544172 DOI: 10.1111/php.13602] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/28/2022] [Indexed: 11/27/2022]
Abstract
The effectiveness of UVC to reduce airborne‐mediated disease transmission is well established. However, conventional germicidal UVC (~254 nm) cannot be used directly in occupied spaces because of the potential for damage to the skin and eye. A recently studied alternative with the potential to be used directly in occupied spaces is far UVC (200–235 nm, typically 222 nm), as it cannot penetrate to the key living cells in the epidermis. Optimal far‐UVC use is hampered by limited knowledge of the precise wavelength dependence of UVC‐induced DNA damage, and thus we have used a monochromatic UVC exposure system to assess wavelength‐dependent DNA damage in a realistic 3‐D human skin model. We exposed a 3‐D human skin model to mono‐wavelength UVC exposures of 100 mJ/cm2, at UVC wavelengths from 215 to 255 nm (5 nm steps). At each wavelength, we measured yields of DNA‐damaged keratinocytes, and their distribution within the layers of the epidermis. No increase in DNA damage was observed in the epidermis at wavelengths from 215 to 235 nm, but at higher wavelengths (240–255 nm) significant levels of DNA damage was observed. These results support use of far‐UVC radiation to safely reduce the risk of airborne disease transmission in occupied locations.
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Affiliation(s)
- David Welch
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Marilena Aquino de Muro
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Manuela Buonanno
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - David J Brenner
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, 10032, USA
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Ma B, Gundy PM, Gerba CP, Sobsey MD, Linden KG. UV Inactivation of SARS-CoV-2 across the UVC Spectrum: KrCl* Excimer, Mercury-Vapor, and Light-Emitting-Diode (LED) Sources. Appl Environ Microbiol 2021; 87:e0153221. [PMID: 34495736 PMCID: PMC8552892 DOI: 10.1128/aem.01532-21] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 08/31/2021] [Indexed: 01/22/2023] Open
Abstract
Effective disinfection technology to combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can help reduce viral transmission during the ongoing COVID-19 global pandemic and in the future. UV devices emitting UVC irradiation (200 to 280 nm) have proven to be effective for virus disinfection, but limited information is available for SARS-CoV-2 due to the safety requirements of testing, which is limited to biosafety level 3 (BSL3) laboratories. In this study, inactivation of SARS-CoV-2 in thin-film buffered aqueous solution (pH 7.4) was determined across UVC irradiation wavelengths of 222 to 282 nm from krypton chloride (KrCl*) excimers, a low-pressure mercury-vapor lamp, and two UVC light-emitting diodes. Our results show that all tested UVC devices can effectively inactivate SARS-CoV-2, among which the KrCl* excimer had the best disinfection performance (i.e., highest inactivation rate). The inactivation rate constants of SARS-CoV-2 across wavelengths are similar to those for murine hepatitis virus (MHV) from our previous investigation, suggesting that MHV can serve as a reliable surrogate of SARS-CoV-2 with a lower BSL requirement (BSL2) during UV disinfection tests. This study provides fundamental information on UVC's action on SARS-CoV-2 and guidance for achieving reliable disinfection performance with UVC devices. IMPORTANCE UV light is an effective tool to help stem the spread of respiratory viruses and protect public health in commercial, public, transportation, and health care settings. For effective use of UV, there is a need to determine the efficiency of different UV wavelengths in killing pathogens, specifically SARS-CoV-2, to support efforts to control the ongoing COVID-19 global pandemic and future coronavirus-caused respiratory virus pandemics. We found that SARS-CoV-2 can be inactivated effectively using a broad range of UVC wavelengths, and 222 nm provided the best disinfection performance. Interestingly, 222-nm irradiation has been found to be safe for human exposure up to thresholds that are beyond those effective for inactivating viruses. Therefore, applying UV light from KrCl* excimers in public spaces can effectively help reduce viral aerosol or surface-based transmissions.
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Affiliation(s)
- Ben Ma
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado, USA
| | - Patricia M. Gundy
- Department of Environmental Science, University of Arizona, Tucson, Arizona, USA
| | - Charles P. Gerba
- Department of Environmental Science, University of Arizona, Tucson, Arizona, USA
| | - Mark D. Sobsey
- Department of Environmental Science and Engineering, Gillings School of Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Karl G. Linden
- Department of Civil, Environmental, and Architectural Engineering, University of Colorado Boulder, Boulder, Colorado, USA
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Sliney DH, Stuck BE. A Need to Revise Human Exposure Limits for Ultraviolet UV-C Radiation †. Photochem Photobiol 2021; 97:485-492. [PMID: 33590879 PMCID: PMC8252557 DOI: 10.1111/php.13402] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/28/2021] [Accepted: 02/09/2021] [Indexed: 01/03/2023]
Abstract
The COVID‐19 pandemic has greatly heightened interest in ultraviolet germicidal irradiation (UVGI) as an important intervention strategy to disinfect air in medical treatment facilities and public indoor spaces. However, a major drawback of UVGI is the challenge posed by assuring safe installation of potentially hazardous short‐wavelength (UV‐C) ultraviolet lamps. Questions have arisen regarding what appear to be unusually conservative exposure limit values in the UV‐C spectral band between 180 and 280 nm. We review the bases for the current limits and proposes some adjustments that would provide separate limits for the eye and the skin at wavelengths less than 300 nm and to increase both skin and eye limits in the UV‐C below 250 nm.
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Affiliation(s)
- David H Sliney
- Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
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