(Request for Information) Evaluation of Germicidal Far-UVC: Safety, Efficacy, Technology, and Adoption

As of August 1st, 2023, this RFI is closed.

Open Philanthropy is interested in exploring and potentially supporting novel opportunities to reduce pathogen transmission in the built environment, as part of our work on biosecurity and pandemic preparedness. Recently highlighted by the COVID-‍19 pandemic, the need for safe and effective disinfection solutions is vital to prevent pandemics and improve global health. Far-Ultraviolet-C light (Far-UVC), emitted between 200–240 nm, is a promising disinfection technology with minimal currently-identified adverse health outcomes.

Open Philanthropy seeks to understand recent insights and advances pertaining to the safety, efficacy, technological development, environmental impacts and considerations, and adoption strategy of Far-UVC. For this request for information (RFI), Open Philanthropy seeks to understand long-term potential for the use of Far-UVC to reduce pathogen transmission in the built environment and aid in preventing future pandemics. Open Philanthropy requests information about innovative approaches, ambitious operational paradigms, and technological advances for Far-UVC (or, with compelling arguments, alternate technologies).

Background

Open Philanthropy identifies and supports high-risk, high-reward activities including reducing the threat of major global disruptions from pandemics. Traditional disinfection methods often require caustic/toxic chemicals or harmful UV radiation, limiting their usage in occupied spaces. Furthermore, differences in microbe susceptibility to chemical disinfectants and germicidal UV impact efficacy, and in some cases can lead to an evolved resistance. High-infection-potential locations (e.g., hospitals and retirement homes) and highly trafficked areas (e.g., airports, office buildings, and shopping malls) pose significant risk for transmission, especially for aerosolized pathogens.

The COVID-‍19 pandemic and other risks from biological threats have propelled research to find disinfection alternatives; of particular interest are approaches that are no-touch or automated, can ideally be used in occupied spaces, have universal or near-universal efficacy against pathogens, and have the potential to substantially reduce or eliminate the transmission of airborne pathogens. One such candidate is Far-UVC disinfection.

Unlike UV-A and UV-B, UV-C light (100–280 nm) from the sun is filtered by the ozone layer. Terrestrial organisms have not been exposed to UV-C light. UV-C exposure often overwhelms the intrinsic processes for protection against or repair of UV-induced damage. UV-C light has strong and reliable germicidal effects—previously demonstrated at the 254-nm emission of mercury vapor lamps—that have been used for nearly a century to sterilize unoccupied rail cars, buses, and public buildings (e.g., schools)^[1]Bergman R. S. (2021). Germicidal UV Sources and Systems. Photochemistry and Photobiology, 97(3), 466–470.^[2]Reed N. G. (2010). The history of ultraviolet germicidal irradiation for air disinfection. Public Health Reports (Washington, D.C. : 1974), 125(1), 15–27. . UV-C exposure inactivates pathogens by inducing DNA damage, and thus preventing multiplication and infection.

Unfortunately, direct exposure to 254-nm UV-C light has detrimental human health outcomes including skin inflammation and reddening (erythema), and photokeratitis and photoconjunctivitis in the eyes. Recent research identified Far-UVC wavelengths with equal disinfection potential to 254 nm while showing minimal adverse health impacts.^[3]Kousha, O., O’Mahoney, P., Hammond, R., Wood, K., & Eadie, E. (2023). 222 nm Far-UVC from filtered Krypton-Chloride excimer lamps does not cause eye irritation when deployed in a simulated office environment. Photochemistry and Photobiology, 10.1111/php.13805. Advance online publication. ^[4]Eadie, E., Hiwar, W., Fletcher, L., Tidswell, E., O’Mahoney, P., Buonanno, M., Welch, D., Adamson, C. S., Brenner, D. J., Noakes, C., & Wood, K. (2022). Far-UVC (222 nm) efficiently inactivates an airborne pathogen in a room-sized chamber. Scientific Reports, 12(1), 4373. ^[5]Ivanova, I., Svilenska, T., Kurz, B., Grobecker, S., Maisch, T., Berneburg, M., & Kamenisch, Y. (2022). Improved Spectral Purity of 222-nm Irradiation Eliminates Detectable Cyclobutylpyrimidine Dimers Formation in Skin Reconstructs even at High and Repetitive Disinfecting Doses. Photochemistry … Continue reading^[6]Welch, D., Buonanno, M., Buchan, A. G., Yang, L., Atkinson, K. D., Shuryak, I., & Brenner, D. J. (2022). Inactivation Rates for Airborne Human Coronavirus by Low Doses of 222 nm Far-UVC Radiation. Viruses, 14(4), 684. ^[7]Buonanno, M., Welch, D., Shuryak, I., & Brenner, D. J. (2020). Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses. Scientific Reports, 10(1), 10285 ^[8]Fukui, T., Niikura, T., Oda, T., Kumabe, Y., Ohashi, H., Sasaki, M., Igarashi, T., Kunisada, M., Yamano, N., Oe, K., Matsumoto, T., Matsushita, T., Hayashi, S., Nishigori, C., & Kuroda, R. (2020). Exploratory clinical trial on the safety and bactericidal effect of 222-nm ultraviolet C … Continue reading^[9]Yamano, N., Kunisada, M., Kaidzu, S., Sugihara, K., Nishiaki-Sawada, A., Ohashi, H., Yoshioka, A., Igarashi, T., Ohira, A., Tanito, M., & Nishigori, C. (2020). Long-term Effects of 222-nm ultraviolet radiation C Sterilizing Lamps on Mice Susceptible to Ultraviolet Radiation. Photochemistry … Continue reading^[10]Buonanno, M., Ponnaiya, B., Welch, D., Stanislauskas, M., Randers-Pehrson, G., Smilenov, L., Lowy, F. D., Owens, D. M., & Brenner, D. J. (2017). Germicidal Efficacy and Mammalian Skin Safety of 222-nm UV Light. Radiation Research, 187(4), 483–491.^[11]Buonanno, M., Stanislauskas, M., Ponnaiya, B., Bigelow, A. W., Randers-Pehrson, G., Xu, Y., Shuryak, I., Smilenov, L., Owens, D. M., & Brenner, D. J. (2016). 207-nm UV Light-A Promising Tool for Safe Low-Cost Reduction of Surgical Site Infections. II: In-Vivo Safety Studies. PloS one, 11(6), … Continue reading

Current research, primarily focused on 222 nm, shows Far-UVC is mostly absorbed by the dead, protein-filled cells in the outer layer of the skin (stratum corneum) and the superficial epithelial cells of the eye, whereas the UV-B wavelengths in sunlight readily penetrate through the epidermis and even into the dermis, damaging the critical germinative cells in the basal layer. Current scientific understanding suggests that decreased penetration does not diminish germicidal action on microbes as they are much smaller than mammalian cells.

Currently, the most common 222-nm sources use krypton chloride (KrCl) lamps with filters to reduce exposure to harmful wavelengths outside the Far-UVC band. Krypton bromide (KrBr) lamps, which emit light at 207 nm, are also used, but are less prevalent and less studied. There are several emerging solid-state technologies for Far-UVC generation, including light-emitting diodes (LEDs). LEDs have many advantages over current vapor lamps including wavelength tunability, durability, miniaturization, and high theoretical efficiency. Current limitations for producing durable Far-UVC LEDs include material quality, electrical conductivity, optical transparency, and scalable fabrication maturity^[12]Zollner, C. J., DenBaars, S. P., Speck, J. S., Namakura, S. (2021). Germicidal Ultraviolet LEDs: A Review of Applications and Semiconductor Technologies. Semiconductor Science and Technology, 36(12). Further applications of solid-state technologies, including second-harmonic generation and electron-beam pumping, have shown promise, but are currently hindered by low efficiency or emission of wavelengths outside the Far-UVC range^[13]Yoo, S. T., & Park, K. C. (2020). Sapphire Wafer for 226 nm Far UVC Generation with Carbon Nanotube-Based Cold Cathode Electron Beam (C-Beam) Irradiation. ACS omega, 5(25), 15601–15605^[14]Oto, T., Banal, R. G., Kataoka, K., Funato, & M., Kawakami, Y. (2010). 100 mW Deep-Ultraviolet Emission From Aluminum-Nitride-Based Quantum Wells Pumped by an Electron Beam. Nature Photonics, 4, 767-770. ^[15]Yuan, J., Kang, Z., Li, F., Zhou, G., Zhang, X., Mei, C., Sang, X., Wu, Q., Yan, B., Zhou, X., Zhong, K., Wang, K., Yu, C., Lu, C., Tam, H. Y., & Wai, P. K. A. (2017). Deep-ultraviolet second-harmonic generation by combined degenerate four-wave mixing and surface nonlinearity polarization in … Continue reading. 

Requested Information

Open Philanthropy requests information about any advances and limitations to Far-UVC technology and systems surrounding safety, efficacy, technology development, environmental impacts, built-environment considerations, adoption strategies, and regulatory hurdles. Additionally, Open Philanthropy seeks any reasons to believe there will (or will not) be other advances or strategies to advance beyond listed and non-listed shortcomings.

Respondents are encouraged to share an ambitious vision for airborne germicidal disinfection using Far-UVC and/or alternative solutions. Ideal responses will articulate what might be possible in 20+ years of advancement, while emphasizing the short-term challenges that must be understood and overcome. In evaluating new Far-UVC approaches, Open Philanthropy requests information on the following:

1. Safety profiles of Far-UVC on humans and other organisms including insects, worms, plants, algae, fungi, pets, etc.
2. Impact on ozone generation, secondary air chemistry, indoor/outdoor air quality, and interactions with materials (degradation, yellowing, outgassing, etc.).
3. Evidence or modeling of Far-UVC emitter impacts with respect to environmental factors including, but not limited to, relative humidity, presence of dust or other particles, surface (plastics, metal, wood, etc.) and clothing material.
4. Efficacy in real world settings, with emphasis on epidemiological outcomes (number of infections), pathogen exposure limits, emitter placement/position, pointing direction, etc.
5. Existing, newly proposed, or potential technology for generating Far-UVC efficiently and safely with considerations including output wavelength, efficiency, output power, radiant flux, optical filtering, etc.
6. Sensors or other technologies for monitoring Far-UVC exposure, harmful wavelengths, or other dangerous co-factors such as ozone and smog generation.
7. Pertinent factors relating to the built environment and implementation in real-world settings including, but not limited to, implementation of pathogen or room-occupancy sensors.
8. Limitations to current Far-UVC safety studies or technology that may hinder development and deployment including analysis of why suggested technologies may not work and the bounds of performance. 
9. Development of local and international adoption strategies, policies, and regulations necessary for implementation including potential barriers or bottlenecks. 
10. High-level cost-effectiveness analysis of Far-UVC as a method of infection control compared to existing state of the art on quality adjusted life years.
11. Any relevant comparisons for the appropriate topic areas.

Instructions

Who can submit: Open Philanthropy welcomes responses from all sources and from anywhere in the world. This includes: academic students, staff, and faculty; nonprofit or corporate employees; volunteers and private individuals; and government or national lab personnel.

Submission due date: 5:00PM PDT on August 1, 2023 (extended from July 24)

Submission instructions: Responses should be submitted through this form. 

Questions: Questions can be submitted through this form and may be answered directly or added to a rolling FAQ.

Format: Submissions should follow formatting requirements outlined in the response template.

All pertinent information should be contained in the response to this request. Links to websites or other external references run the risk of not being seen by Open Philanthropy.

Disclaimers and Important Notes

This is an RFI issued solely for information gathering and potential future funding planning purposes; this RFI does not constitute a formal solicitation for proposals or proposal abstracts. Responses to this notice are not offers for a grant and cannot be accepted by Open Philanthropy or you to form a binding contract. Submission of a response is strictly voluntary and is not required to propose to subsequent Request for Proposals (if any) or research solicitations (if any) on this topic. Open Philanthropy will not provide reimbursement for costs incurred in responding to this RFI. Respondents are advised that Open Philanthropy is under no obligation to acknowledge receipt of the information received or provide feedback to respondents with respect to any information submitted under this RFI.

NOTE: Open Philanthropy intends to conduct individual discussions with respondents as necessary to gain a full understanding of the responses submitted. Open Philanthropy will contact respondents via email.

To the maximum extent possible, please submit non-proprietary information. If absolutely necessary, responses can contain confidential or proprietary information, but only if it is clearly marked as “Proprietary” and only if you have the authority to disclose that information to Open Philanthropy. Open Philanthropy will disclose submission contents labeled “Proprietary” only for the purpose of review by Open Philanthropy staff and contract support personnel who have agreed with Open Philanthropy to maintain the confidentiality of such information, or as otherwise may be required by law. Please note that Open Philanthropy may already be in possession of, or separately may obtain, information similar or identical to your proprietary information, and Open Philanthropy remains free to use any of that information without restriction.