Med Lasers 2024; 13(1): 12-18  https://doi.org/10.25289/ML.24.009
The potential of 222-nm wavelength ultraviolet light for medical applications: a review
Yeon Soo Kim, A Jeong You, Sunho Lee, Kwang Yoon Jung, Seung-Kuk Baek
Department of Otolaryngology-Head and Neck Surgery, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Republic of Korea
Correspondence to: Seung-Kuk Baek
E-mail: mdbsk@korea.ac.kr
ORCID: https://orcid.org/0000-0002-4751-0337
Received: March 11, 2024; Accepted: March 20, 2024; Published online: March 30, 2024.
© Korean Society for Laser Medicine and Surgery. All rights reserved.

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
In recent years, there has been a growing interest in the use of 222-nm wavelength ultraviolet (UV) light for medical applications due to its potent germicidal properties and reduced risk of harm to human tissue. This review explores the current state of research surrounding the utilization of 222 nm UVC light in various medical settings. We discuss its efficacy in disinfection, potential applications in wound healing, and dermatology, and its role in combating airborne pathogens. Furthermore, we address safety considerations and future directions for research and development in this promising field.
Keywords: Light; Treatment; Safety; Pathogen
INTRODUCTION

The emergence of antibiotic-resistant bacteria and the ongoing threat of pandemics have underscored the importance of effective disinfection methods in healthcare settings [1]. Traditional ultraviolet C (UVC) germicidal lamps have long been used for surface and air disinfection but are limited by their potential harm to human skin and eyes at wavelengths below 230 nm [1,2]. However, recent studies have demonstrated that far-UVC light at 222 nm exhibits potent germicidal properties while posing minimal risk to human tissue, opening up new possibilities for medical applications [3-6].

MAIN TEXT

What is the 222 nm wavelength light?

A 222 nm wavelength light refers to UV radiation with a specific wavelength of 222 nm. UV light is a form of electromagnetic radiation with shorter wavelengths than visible light, making it invisible to the human eye.

UV light is categorized into different bands based on its wavelength (Fig. 1):

Figure 1. Category of ultraviolet (UV) light base on its wavelength.

UVA (320-400 nm), UVB (280-320 nm), UVC (200-280 nm)

The 222 nm wavelength falls within the UVC range. UVC light is known for its germicidal properties, as it can effectively inactivate bacteria, viruses, and other microorganisms by damaging their DNA or RNA. This makes UVC light a valuable tool for disinfection purposes in various applications, including water treatment, air purification, and sterilization of surfaces and medical equipment.

The specific wavelength of 222 nm has garnered attention because it exhibits potent germicidal efficacy while posing minimal risk of harm to human tissue. Recent research suggests that 222 nm UVC light can effectively disinfect without causing significant damage to skin or eyes, unlike longer wavelengths of UV light that are commonly used for germicidal purposes (Fig. 2). This has led to investigations into the potential use of 222 nm UVC light for medical applications such as wound healing, dermatology, and air disinfection [7-10].

Figure 2. Safety effect of 222 nm wavelength light for skin and eyes.

Industrial application of 222 nm wavelength light

A 222 nm wavelength light is commonly used in industrial applications for disinfection purposes [11-15]. These lights utilize UV radiation at a specific wavelength to effectively kill or deactivate bacteria, viruses, and other pathogens. They are often employed in settings such as water treatment facilities, food processing plants, pharmaceutical manufacturing, and air purification systems. The 222 nm wavelength is particularly effective at disinfection while minimizing potential harm to human tissue, making it a preferred choice in various industries where cleanliness and sterilization are paramount. Recently, we can order these 222 nm wavelength light lamp for disinfection purposes.

Corona virus and 222 nm wavelength light

Germicidal efficacy: Studies have demonstrated that 222 nm UVC light possesses potent germicidal properties, capable of inactivating a wide range of viruses, including coronaviruses, by damaging their genetic material. This makes it a promising tool for disinfection in various settings, including healthcare facilities, public transportation, and indoor environments [5].

Reduced photobiological hazard: Unlike longer wavelengths of UV light, which can penetrate deeper into human tissue and cause damage to skin and eyes, 222 nm UVC light has a limited penetration depth and is less likely to harm exposed individuals. This selectivity allows for targeted disinfection without significant risk of adverse effects.

Airborne pathogen control: Given the potential for respiratory transmission of coronaviruses like SARS-CoV-2, there is growing interest in the use of 222 nm UVC light for air disinfection. Studies have shown that continuous irradiation with far-UVC light can effectively inactivate aerosolized viruses, including coronaviruses, thereby reducing the risk of airborne transmission in indoor environments.

Potential applications in infection control: Incorporating 222 nm UVC light into existing infection control measures may help mitigate the spread of coronaviruses and other infectious diseases, particularly in high-risk settings such as hospitals, long-term care facilities, and crowded public spaces. By providing an additional layer of protection against viral contamination, far-UVC technology could play a crucial role in reducing the burden of respiratory infections and enhancing public health safety.

Medical applications

Germicidal efficacy: Numerous studies have confirmed the efficacy of 222 nm wavelength light in inactivating a wide range of pathogens, including bacteria, viruses, and fungi. Unlike conventional UVC lamps, which primarily emit light at wavelengths around 254, 222 nm light can penetrate microbial cell membranes without causing significant damage to mammalian cells due to its limited penetration depth in human tissues. This selectivity makes it a promising tool for targeted disinfection in medical environments.

Applications in wound healing

Applications of 222 nm wavelength light in wound healing are an emerging area of research with promising potential. Here’s an overview of how this specific wavelength light can be utilized in wound care [6-8].

Bacterial decontamination: Wound infections are a common complication in the healing process. UVC light with a wavelength of 222 nm has demonstrated effective bactericidal properties against a wide range of pathogens, including antibiotic-resistant bacteria. By selectively targeting and destroying bacteria on the wound surface without harming surrounding healthy tissue, 222 nm UVC light can help prevent or reduce the risk of infection, facilitating faster wound healing.

Reducing inflammation: Inflammation is a natural response to tissue injury, but excessive or prolonged inflammation can impair the healing process. Studies suggest that exposure to 222 nm UVC light may help modulate inflammatory responses in wounded tissue, leading to a reduction in inflammation. By promoting a more balanced inflammatory environment, 222 nm UVC light could facilitate more efficient wound healing and tissue regeneration.

Stimulation of cellular repair mechanisms: UV radiation, including 222 nm UVC light, has been shown to stimulate various cellular repair mechanisms involved in wound healing. This includes the upregulation of collagen synthesis, proliferation of fibroblasts (cells involved in tissue repair), and enhanced angiogenesis (formation of new blood vessels). By promoting these cellular processes, 222 nm UVC light can accelerate the formation of granulation tissue and epithelialization, crucial stages in the wound healing cascade.

Potential for chronic wound management: Chronic wounds, such as diabetic ulcers and pressure sores, pose significant challenges in clinical management due to impaired healing mechanisms and susceptibility to infection. Preliminary studies indicate that 222 nm UVC light therapy may offer a novel approach for the treatment of chronic wounds. By targeting both microbial pathogens and underlying inflammatory processes, 222 nm UVC light has the potential to improve wound healing outcomes in patients with chronic or non-healing wounds.

Minimal risk of adverse effects: One of the key advantages of 222 nm UVC light is its minimal risk of adverse effects on human tissue. Unlike longer wavelengths of UV light, which can penetrate deeper into the skin and cause damage to cells and DNA, 222 nm UVC light has a limited penetration depth and is selectively absorbed by microbial DNA. This selectivity ensures that exposure to 222 nm UVC light is well-tolerated and safe for use in wound healing applications.

The use of 222 nm wavelength light shows promise as a novel therapeutic approach in wound healing. By harnessing its bactericidal properties, anti-inflammatory effects, and ability to stimulate cellular repair mechanisms, 222 nm UVC light has the potential to improve the management of acute and chronic wounds, ultimately leading to faster healing and better clinical outcomes for patients. Further research and clinical trials are warranted to fully explore the therapeutic benefits and safety profile of 222 nm UVC light in wound healing applications.

Dermatological applications

Applications of 222 nm wavelength light in dermatology represent a promising avenue for various skin-related conditions and therapies. Here’s a breakdown of potential applications [4-8]:

Psoriasis treatment: Psoriasis is a chronic autoimmune skin condition characterized by red, itchy, and scaly patches on the skin. Traditional treatment options include topical corticosteroids, phototherapy using UVB or psoralen plus ultraviolet A (PUVA), and systemic medications. However, these treatments can be associated with side effects such as skin thinning, photosensitivity, and increased risk of skin cancer. Preliminary studies suggest that 222 nm UVC light may offer a safer alternative for psoriasis treatment. By selectively targeting hyperactive immune cells in the skin without penetrating deeply into underlying tissues, 222 nm UVC light can reduce inflammation and promote the resolution of psoriatic lesions.

Eczema (atopic dermatitis) management: Eczema, also known as atopic dermatitis, is a common inflammatory skin condition characterized by dry, itchy, and inflamed skin. Conventional treatments for eczema include topical corticosteroids, moisturizers, and immunosuppressive medications. However, these treatments are often associated with adverse effects and may provide only temporary relief. UVC light with a wavelength of 222 nm therapy has shown promise as a potential treatment modality for eczema by targeting inflammatory mediators in the skin and promoting the restoration of the skin barrier function. By modulating immune responses and reducing inflammation, 222 nm UVC light may offer an effective and well-tolerated option for eczema management.

Acne treatment: Acne is a common skin condition characterized by the formation of comedones (blackheads and whiteheads), papules, pustules, nodules, and cysts. Topical and oral medications, such as retinoids, antibiotics, and hormonal therapies, are commonly used to treat acne. However, these treatments can be associated with side effects such as skin irritation, dryness, and antibiotic resistance. Preliminary studies suggest that 222 nm UVC light therapy may have antimicrobial and anti-inflammatory effects that can help reduce acne lesions and improve overall skin appearance. By targeting acne-causing bacteria (Propionibacterium acnes) and reducing inflammation in the skin, 222 nm UVC light may offer a novel approach to acne treatment with fewer side effects.

Phototherapy for skin disorders: Phototherapy, or light therapy, is a well-established treatment modality for various skin disorders, including psoriasis, eczema, vitiligo, and cutaneous T-cell lymphoma. Traditional phototherapy techniques involve the use of UVB or PUVA light sources, which can be associated with adverse effects such as erythema, phototoxicity, and increased risk of skin cancer. UVC light with a wavelength of 222 nm therapy offers a potential alternative for phototherapy with reduced risk of adverse effects. By delivering targeted doses of UVC light to affected areas of the skin, 222 nm UVC light therapy can effectively treat a wide range of dermatological conditions while minimizing the risk of systemic side effects.

Overall, the applications of 222 nm wavelength light in dermatology represent a promising and rapidly evolving field. Further research and clinical studies are needed to fully elucidate the therapeutic benefits and safety profile of 222 nm UVC light therapy for various dermatological conditions. With continued advancements in technology and research, 222 nm UVC light therapy has the potential to revolutionize the management of skin disorders and improve patient outcomes in dermatology.

Airborne pathogen control

Applications of 222 nm wavelength light in airborne pathogen control represent an innovative approach to mitigating the spread of infectious diseases in indoor environments. Here are some potential applications [5-8].

Air disinfection in healthcare settings: Hospitals and healthcare facilities are at heightened risk for the spread of airborne pathogens, including bacteria, viruses, and fungi. Continuous irradiation with 222 nm UVC light can effectively inactivate airborne pathogens, reducing the risk of healthcare-associated infections and protecting both patients and healthcare workers. Installing 222 nm UVC light fixtures in ventilation systems, patient rooms, and high-traffic areas can help enhance infection control measures and improve overall air quality in healthcare settings.

Public transportation: Public transportation systems, such as buses, trains, and airplanes, are potential hotspots for the transmission of respiratory infections due to close proximity and limited ventilation. Integrating 222 nm UVC light technology into heating, ventilation, and air conditioning (HVAC) systems and air filtration systems can help disinfect recirculated air and reduce the spread of airborne pathogens among passengers. This can be particularly beneficial during outbreaks of contagious diseases such as influenza, coronavirus disease 2019, and tuberculosis.

Schools and educational facilities: Educational institutions, including schools, colleges, and universities, often face challenges in controlling the spread of respiratory infections among students, faculty, and staff. Incorporating 222 nm UVC light fixtures in classrooms, libraries, and common areas can help minimize the risk of airborne transmission of pathogens, thereby promoting a healthier learning environment and reducing absenteeism due to illness.

Office buildings and workplaces: Office buildings and workplaces are communal environments where employees spend a significant amount of time in close proximity to one another. Airborne pathogens can spread easily in such settings, leading to outbreaks of respiratory illnesses and decreased productivity. Implementing 222 nm UVC light technology in HVAC systems and air purification systems can help disinfect indoor air and create a safer working environment for employees.

Residential settings: Residential settings, including homes, apartments, and condominiums, can also benefit from the use of 222 nm UVC light technology to control airborne pathogens. Portable or stationary UVC air purifiers equipped with 222 nm UVC light bulbs can be used to disinfect indoor air and reduce the risk of respiratory infections among household members. This can be particularly advantageous for individuals with compromised immune systems or respiratory conditions.

Public spaces and high-traffic areas: Public spaces such as shopping malls, airports, restaurants, and entertainment venues attract large numbers of people and are potential breeding grounds for airborne pathogens. Integrating 222 nm UVC light technology into existing ventilation systems and air filtration systems can help minimize the risk of airborne transmission of infectious diseases in high-traffic areas, thereby enhancing public health safety and confidence.

Overall, the applications of 222 nm wavelength light in airborne pathogen control hold great promise for improving indoor air quality, reducing the spread of infectious diseases, and enhancing public health safety in various settings. Continued research, technological advancements, and implementation strategies are needed to fully realize the potential of 222 nm UVC light technology in combating airborne pathogens and promoting healthier environments for all.

Safety considerations

Applications of 222 nm wavelength light carry significant potential for various fields, but they also require careful consideration of safety measures. Here are key safety considerations for the use of 222 nm wavelength light [6,16-22].

Minimal risk to human tissue: One of the primary advantages of 222 nm UVC light is its limited penetration depth in human tissue. Unlike longer wavelengths of UV light, which can penetrate deeply and cause damage to cells and DNA, 222 nm UVC light is selectively absorbed by microbial DNA while posing minimal risk to human tissue. However, prolonged exposure to 222 nm UVC light can still cause erythema (skin redness) and photokeratitis (eye irritation), emphasizing the importance of proper safety protocols.

Exposure limits and dosimetry: Establishing safe exposure limits and dosimetry parameters is crucial for minimizing the risk of adverse effects associated with 222 nm UVC light exposure. This includes determining appropriate irradiance levels, exposure durations, and distances from the light source to ensure effective disinfection while preventing overexposure to individuals in the vicinity. Regulatory guidelines and occupational safety standards should be followed to ensure compliance with safety requirements.

Engineering controls: Implementing engineering controls is essential for mitigating the risk of accidental exposure to 222 nm UVC light. This may include the use of shielding mechanisms, containment enclosures, and interlocks to prevent direct exposure of individuals to the light source. Proper ventilation and exhaust systems should also be in place to minimize the dispersion of airborne contaminants generated during UVC disinfection processes.

Personal protective equipment (PPE): Personnel involved in operating or maintaining 222 nm UVC light systems should wear appropriate PPE to minimize the risk of exposure. This may include gloves, protective eyewear, face shields, and lab coats to shield exposed skin and mucous membranes from direct contact with UVC radiation. Training on the proper use of PPE and adherence to safety protocols are essential for ensuring worker safety.

Occupational health monitoring: Regular monitoring of occupational exposure to 222 nm UVC light is necessary to assess potential health risks and ensure compliance with safety regulations. This may involve periodic measurements of UVC light levels in the work environment, as well as medical surveillance programs to monitor the health status of personnel exposed to UVC radiation. Early detection of adverse effects allows for timely intervention and mitigation of occupational hazards.

Emergency response plans: Developing comprehensive emergency response plans is essential for effectively managing incidents involving 222 nm UVC light exposure. This includes procedures for responding to accidental spills or releases of UVC disinfection agents, as well as protocols for providing medical assistance to individuals who may experience adverse effects. Personnel should be trained on emergency response procedures and evacuation protocols to ensure a prompt and coordinated response to safety incidents.

By addressing these safety considerations and implementing appropriate measures, the use of 222 nm wavelength light can be conducted in a safe and responsible manner, minimizing the risk of harm to individuals while maximizing the benefits of UVC disinfection technologies in various applications. Ongoing research, education, and collaboration among stakeholders are essential for advancing the safe and effective use of 222 nm UVC light for the benefit of public health and safety.

Future directions: As research into the medical applications of 222 nm wavelength light continues to evolve, future studies should focus on optimizing dosimetry, exploring novel delivery methods, and conducting large-scale clinical trials to validate its efficacy and safety in real-world settings. Collaborative efforts between scientists, engineers, and healthcare professionals will be essential to harness the full potential of far-UVC technology in improving patient outcomes and mitigating the spread of infectious diseases.

CONCLUSION

Light with a wavelength of 222 nm holds great promise for medical applications ranging from surface and air disinfection to wound healing and dermatological therapy. Its unique combination of potent germicidal efficacy and minimal photobiological hazard makes it a valuable tool for enhancing infection control measures and advancing patient care. Continued research and innovation in this field are essential to unlock the full therapeutic potential of far-UVC light and improve public health outcomes worldwide.

SUPPLEMENTARY MATERIALS

None.

ACKNOWLEDGMENTS

None.

AUTHOR CONTRIBUTIONS

Conceptualization: YSK. Data curation: AJY. Formal analysis: SL. Investigation: KYJ. Methodology: SKB. Project administration: SKB. Software: YSK. Validation: YSK. Visualization: SL. Writing–original draft: YSK. Writing–review & editing: all authors.

CONFLICT OF INTEREST

Seung-Kuk Baek is an editorial board member of the journal, but was not involved in the review process of this manuscript. Otherwise, there is no conflict of interest to declare.

FUNDING

None.

DATA AVAILABILITY

None.

References
  1. Kowalski W. Ultraviolet germicidal irradiation handbook: UVGI for air and surface disinfection. Springer; 2009.
    CrossRef
  2. Budowsky EI, Bresler SE, Friedman EA, Zheleznova NV. Principles of selective inactivation of viral genome. I. UV-induced inactivation of influenza virus. Arch Virol 1981;68:239-47.
    Pubmed CrossRef
  3. Naunovic Z, Lim S, Blatchley ER 3rd. Investigation of microbial inactivation efficiency of a UV disinfection system employing an excimer lamp. Water Res 2008;42:4838-46.
    Pubmed CrossRef
  4. Panzures A. 222-nm UVC light as a skin-safe solution to antimicrobial resistance in acute hospital settings with a particular focus on methicillin-resistant Staphylococcus aureus and surgical site infections: a review. J Appl Microbiol 2023;134:lxad046.
    Pubmed CrossRef
  5. Buonanno M, Welch D, Shuryak I, Brenner DJ. Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses. Sci Rep 2020;10:10285. Erratum in: Sci Rep 2021;11:19569.
    Pubmed KoreaMed CrossRef
  6. Narita K, Asano K, Morimoto Y, Igarashi T, Hamblin MR, Dai T, et al. Disinfection and healing effects of 222-nm UVC light on methicillin-resistant Staphylococcus aureus infection in mouse wounds. J Photochem Photobiol B 2018;178:10-8. Erratum in: J Photochem Photobiol B 2018;182:146.
    Pubmed KoreaMed CrossRef
  7. Trevisan A, Piovesan S, Leonardi A, Bertocco M, Nicolosi P, Pelizzo MG, et al. Unusual high exposure to ultraviolet-C radiation. Photochem Photobiol 2006;82:1077-9.
    Pubmed CrossRef
  8. Zaffina S, Camisa V, Lembo M, Vinci MR, Tucci MG, Borra M, et al. Accidental exposure to UV radiation produced by germicidal lamp: case report and risk assessment. Photochem Photobiol 2012;88:1001-4.
    Pubmed CrossRef
  9. Setlow RB, Grist E, Thompson K, Woodhead AD. Wavelengths effective in induction of malignant melanoma. Proc Natl Acad Sci U S A 1993;90:6666-70.
    Pubmed KoreaMed CrossRef
  10. Balasubramanian D. Ultraviolet radiation and cataract. J Ocul Pharmacol Ther 2000;16:285-97.
    Pubmed CrossRef
  11. Narita K, Asano K, Naito K, Ohashi H, Sasaki M, Morimoto Y, et al. 222-nm UVC inactivates a wide spectrum of microbial pathogens. J Hosp Infect 2020;105:459-67.
    Pubmed CrossRef
  12. Buonanno M, Randers-Pehrson G, Bigelow AW, Trivedi S, Lowy FD, Spotnitz HM, et al. 207-nm UV light - a promising tool for safe low-cost reduction of surgical site infections. I: in vitro studies. PLoS One 2013;8:e76968.
    Pubmed KoreaMed CrossRef
  13. Buonanno M, Stanislauskas M, Ponnaiya B, Bigelow AW, Randers-Pehrson G, Xu Y, et al. 207-nm UV light-a promising tool for safe low-cost reduction of surgical site infections. II: in-vivo safety studies. PLoS One 2016;11:e0138418.
    Pubmed KoreaMed CrossRef
  14. Buonanno M, Ponnaiya B, Welch D, Stanislauskas M, Randers-Pehrson G, Smilenov L, et al. Germicidal efficacy and mammalian skin safety of 222-nm UV light. Radiat Res 2017;187:483-91.
    Pubmed KoreaMed CrossRef
  15. Ponnaiya B, Buonanno M, Welch D, Shuryak I, Randers-Pehrson G, Brenner DJ. Far-UVC light prevents MRSA infection of superficial wounds in vivo. PLoS One 2018;13:e0192053.
    Pubmed KoreaMed CrossRef
  16. Chen H, Moraru C. Synergistic effects of sequential light treatment with 222-nm/405-nm and 280-nm/405-nm wavelengths on inactivation of foodborne pathogens. Appl Environ Microbiol 2023;89:e0065023.
    Pubmed KoreaMed CrossRef
  17. 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.
    Pubmed KoreaMed CrossRef
  18. Fukui T, Niikura T, Oda T, Kumabe Y, Ohashi H, Sasaki M, et al. Exploratory clinical trial on the safety and bactericidal effect of 222-nm ultraviolet C irradiation in healthy humans. PLoS One 2020;15:e0235948.
    Pubmed KoreaMed CrossRef
  19. Narita K, Asano K, Morimoto Y, Igarashi T, Nakane A. Chronic irradiation with 222-nm UVC light induces neither DNA damage nor epidermal lesions in mouse skin, even at high doses. PLoS One 2018;13:e0201259.
    Pubmed KoreaMed CrossRef
  20. Yamano N, Kunisada M, Kaidzu S, Sugihara K, Nishiaki-Sawada A, Ohashi H, et al. Long-term effects of 222-nm ultraviolet radiation C sterilizing lamps on mice susceptible to ultraviolet radiation. Photochem Photobiol 2020;96:853-62.
    Pubmed KoreaMed CrossRef
  21. Goldfarb AR, Saidel LJ. Ultraviolet absorption spectra of proteins. Science 1951;114:156-7.
    Pubmed CrossRef
  22. Setlow JK. The effects of ultraviolet radiation and photoreactivation. Compr Biochem 1967;27:157-209.
    CrossRef


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