Far-UVC (222 nm) efficiently inactivates an airborne pathogen in a room-sized chamber

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.

A multi‐layered strategy for COVID ‐19 infection prophylaxis in schools: A review of the evidence for masks, distancing, and ventilation

“…Accidental exposure is a major challenge for devices deploying conventional 254‐nm germicidal ultraviolet (GUV) light since it is known to cause sunburn‐type reactions, while long‐term exposure is linked to photocarcinogenesis 99 . In contrast, research has shown that Far‐UVC (222 nm) does not induce acute reactions in the skin or eyes nor delayed effects such as skin cancer and has been shown to efficiently inactivate the Staphylococcus aureus bacteria 100 . On the basis that previous studies, using a broad range of Far‐UVC wavelengths, have shown comparable surface inactivation of SARS‐COV‐2 101 and airborne human coronaviruses (OC43 and 229E), 102,103 it is likely that Far‐UVC will also be proven effective against SARS‐CoV‐2.…”

Shaping health and well-being in a COVID era: the role of design

“…Researchers suggest using ultraviolet germicidal irradiation, or UV light, to disinfect COVID-19 viruses in particles and droplets, even when absorbed by glass and finishes (Dietz et al, 2020;Hamzavi et al, 2020). UVC light have also been shown to take less than five minutes to reduce indoor airborne microbes by more than 98% (Eadie et al, 2022) Hence, artificial UVC lighting fixtures become important, given proper safety precautions. In the pandemic-era, lighting design in the built environment serves disinfectant purposes as well as wayfinding and operational uses (e.g.…”

“…, 2020). UVC light have also been shown to take less than five minutes to reduce indoor airborne microbes by more than 98% (Eadie et al. , 2022) Hence, artificial UVC lighting fixtures become important, given proper safety precautions.…”

Effect of radiant catalytic ionization on environmental conditions in rodent rooms and the haematological status of mice

“…The vaporized hydrogen peroxide (VHP) sterilization technique and UVC lamps, widely used for disinfecting laboratory rooms, are effective preventive methods. However, they can only be used periodically and when staff and animals are not present [4,5], An exception is lamps emitting wavelengths of 222 nm, as research demonstrates that KrCl lamps can efficiently inactivate pathogens without inducing acute reactions in the skin or eyes or delayed effects such as skin cancer [6]. Improving hygiene or sanitation on breeding farms takes place through the use of numerous chemicals, including water solutions of hydrogen peroxide [7,8].…”