This study used a ceiling-mounted far-UVC fixture emitting at 222 nm and then evaluated the doses received upon a manikin. Variables examined included manikin height (sitting or standing position), manikin offset from directly below the fixture, tilt of the manikin, the addition of glasses, the addition of hair, and different anatomical feature sizes.
Importantly, at the manikin position with the highest dose to eyes, the average eye dose was only 5.8% of the maximum directly measured dose. These results show that doses a human would experience from an indoor far-UVC installation are in fact much lower than the maximum directly measured dose.
This study assessed far-UVC induced carcinogenic skin changes and other abnormalities in hairless mice of both sexes that were exposed to high average daily doses of 222 nm far-UVC radiation for 66 weeks, 5 days per week, 8 hours 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 light, and therefore its potential suitability as a practical anti-microbial approach to reduce airborne viral and bacterial loads in occupied indoor settings.
This study concludes that a much lower far-UVC dose is required than previously thought in order to inactivate the great majority of the airborne aerosolized pathogens in a room environment. The study used human coronavirus OC43 (HCoV-OC43) which is a suitable surrogate for SARS-CoV-2 with comparable physical and genomic size.
These new results offer further evidence as to the efficacy of far-UVC to inactivate airborne pathogens.
Filtered Far-UVC lamps showed reduction of steady-state aerosolized Staphylococcus aureus loads by 92.1%, providing an additional 35 equivalent air changes per hour (eACH). This makes the technology ideal for rooms and buildings lacking mechanical ventilation systems.
Efficacy and eACH results in this study were obtained with lamps operating within current ACGIH/IEC exposure limits. The efficacy and eACH are expected to be significantly higher when ACGIH/IEC adopts the proposed exposure limits (20-time higher than current limits).
This study determined 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.
This study determined that human-safe 222nm Far-UVC light is not only safe, but also more effective at inactivating viruses like SARS-CoV-2 compared to harmful UV wavelengths. As such, it offers immense potential for applications in public spaces to effectively reduce viral aerosol and surface-based transmissions.
Using computer modelling, this study compared skin damage from sunlight to that from Far-UVC sources. In a temperate climate, which is similar to many parts of North American and Europe, 10 minutes of daylight at a UV index of 4 which is typical from Spring to Fall, produced as much damage as 30,000 hours of filtered Far-UVC at the basal layer of the skin and 300 hours at the top of the epidermis.
Effectively, this research concludes that filtered Far-UVC light is about 180,000-times safer than sunlight at the basal layer of the skin under the researched parameters. At the top of the epidermis, filtered Far-UVC light is about 1,800-times safer than sunlight under the researched parameters.
This pilot study in a shared bathroom concludes that 222nm Far-UVC is effective at disinfection in real world environments, and likely more effective that traditional cleaning methods which have "the problem of selecting inappropriate disinfectants; furthermore, some areas might remain uncleaned due to human errors. A previous study showed that only 50% of the surfaces in hospital rooms are sufficiently cleaned."
This study utilized identical lamps as UVX's.
Current management of pressure wounds is limited to mainly conservative measures, such as offloading therapies and regular wound care. Reduction of bacterial load remains an important step in wound bed preparation to encourage wound healing in such wounds.
This research is the first human clinical trial using 222nm Far-UVC in eradicating bacteria in human wounds. The study concludes that filtered 222nm Far-UVC light is effective and safe at reducing bacterial loads on pressure ulcers (PUs) in human patients. No adverse events were reported in any of the patients.
A 37-year-old male, Fitzpatrick Skin Type II, performed multiple self-exposures with a filtered 222 nm Far-UVC lamp. No erythema was observed at any time point with exposures up to 18000 mJ/cm (about 783-timeshigher than maximum exposure limits).
These results combined with Monte Carlo Radiative Transfer computer modeling suggest that filtering longer ultraviolet wavelengths is critical for the human skin safety of far-UVC devices. This work also contributes to growing arguments for the exploration of exposure limit expansion, which would subsequently enable faster inactivation of viruses.
This research compares filtered and unfiltered 222nm Far-UVC lamp safety on skin. The study further emphasizes the importance of using optical filters with 222nm Far-UVC lamps in ensuring safety, concluding that unfiltered Far-UVC lamps result in statistically significant increase in the yield of DNA damage whereas filtered Far-UVC lamps do not induce the same.
The model shows that disinfection rates are increased by an "additional" 50-85% when using 222nm Far-UVC within currently recommended exposure levels compared to the room’s ventilation alone. In all scenarios explored within this research, Far-UVC can reduce in-room SARS-CoV-2 concentrations to levels comparable to that provided practically by breathing through an N95 mask
With these magnitudes of reduction, 222nm Far-UVC light could be employed to mitigate SARS-CoV-2 transmission before the onset of future waves, or the start of winter when risks of infection are higher. This is particularly significant in poorly-ventilated spaces where other means of reduction are not practical, in addition social distancing can be reduced without increasing the risk.
A dosage as small as 3 mJ/cm2 of 222nm Far-UVC light resulted in 99.7% reduction of SARS-CoV-2, the pathogen that causes COVID-19. These results suggest that this technology could be used for infection prevention and control against COVID-19 and other infectious diseases, not only in unoccupied spaces but also occupied spaces.
This study aimed to investigate the safety of 222nm Far-UVC light and to examine its skin sterilization effect in healthy volunteers.
All subjects experienced no skin erythema at all doses. The back of the subject was irradiated at 500 mJ/cm2, and the number of bacterial colonies in the skin swab culture was significantly decreased by 222nm Far-UVC exposure.
A 222nm Far-UVC dosage at 500 mJ/cm2, which is about 22.7-times higher than UVX’s maximum programmed dosage, was a safe irradiation dose while possessing germicidal effects.
This research provides further evidence that filtered 222nmFar-UVC light has no immediate or delayed harmful effects on mice skin andeyes.
Long-term effects of 222nm Far-UVC were investigated on a type of mice species that lacks the genetic ability to repair the most prominent type of DNA damage from conventional non-Far-UVC light.
Despite the mice being significantly more susceptible to UV light by being unable to repair DNA damage, 222nm Far-UVC proved to be non-carcinogenic and safe for both skin and eyes long-term.
222nm Far-UVC is effective at decontaminating airborne human coronaviruses alpha HCoV-229E and beta HCoV-OC43.
Continuous airborne disinfection with 222nm Far-UVC light at the current regulatory limits that UVX follows would provide a major reduction in the ambient level of airborne virus in occupied indoor environments.
This study by Barnard et al emphasizes the importance of using an optical filter to ensure 222nm Far-UVC safety, proving that filtered 222nm Far-UVC is safe but unfiltered 222nm Far-UVC is not.
In 2014, Woods et al undertook a first‐in‐person study to assess the effect on skin of a 222nm Far-UVC emitting device (a disinfection wand). The study concluded that damage was induced on human skin. Woods et al hypothesized that a small amount of longer wavelength UVC light above 250 nm (<3%) may be contributing to the observed effects. These wavelengths were emitted as the 222nm Far-UVC emitting device did not utilize an optical filter to eliminate wavelengths outside the 200nm to 230nm range (the safe wavelengths), with wavelengths below 200nm and above 230nm being unsafe.
This study by Bernard et al concluded that skin damage documented by Woods et al arose from very low intensity source emissions above 230nm due to the lack of an optical filter (as low as 3% above 250nm). With the proper use of an optical filter to eliminate harmful UV wavelengths, this study confirmed that filtered 222nm Far-UVC light is safe for humans and does not induce skin damage.
A Eadie et al case study also confirmed the criticality of an optical filter to ensure 222nm-Far-UVC safety by tests on human skin.
222nm Far-UVC had a potent germicidal effect on vegetative bacterial cells, yeast and viruses, and was as efficient as 245nm UVC. In addition, 222nm Far-UVC had a more potent germicidal effect on bacterial endospores compared with 254nm UVC.
However, the fungicidal effect of 222nm Far-UVC against fungal spores and hyphae was weaker than that of 254nm UVC. UVX’s 222nm Far-UVC technology is not intended for fungal spores disinfection.
No corneal damage was induced by 222nm Far-UVC light, which suggested that 222nm Far-UVC light does not harm rat eyes within the tested dosage ranges. These dosages are significantly higher than UVX’s maximum programmed dosage.
Mice were subjected to daily 222nm Far-UVC dosage of 450 mJ/cm2 per day for a total of 10 days. Despite this dosage being 7-times higher than UVX’s maximum programmed dosage, it did not induce a mutagenic or cytotoxic effect on mice skin.
In the circumstance of superficial incisions infected with bacteria alighting onto the wound, 222nm Far-UVC light showed the same germicidal properties of 254nm UVC light but without the associated skin damage.
Being safe for patient and hospital staff, our results suggested that far-UVC light (222 nm) might be a convenient approach to prevent transmission of drug-resistant infectious agents in the clinical setting.
222nm Far-UVC is effective at decontaminating aerosolized influenza A virus (H1NA) with doses as low as 2 mJ/cm2.
Surgical site infection is the most common type of infection occurring in hospitals, caused by contamination of surgical wounds with natural commensal bacteria and by hospital pathogens, of which methicillin-resistant Staphylococcus aureus (MRSA) is one of the most frequently detected.
222nm Far-UVC is effective at decontaminating MRSA.
222nm Far-UVC is effective at killing MRSA bacteria, produces no DNA lesions in a 3D human skin model, and does not cause cell damage in mammalian skin.
Mice were continuously exposed to a 222nm Far-UVC dosage of 157 mJ/cm2 per 7 hours, more than 8-times UVX's maximum programmed dosage, and still showed no skin damage.
This is Phase 2 of a similar study. Phase 1 of the study was conducted in-vitro whereas Phase 2 was conducted in-vivo.
This study exposed hairless mice to a dosage of 157mJ/cm2 using a filtered Krypton-Bromine Far-UVC lamp with a peak wavelength of 207nm. The same mice species were also exposed to conventional 254nm UVC light.
While conventional 254nm UVC exposure produced significant damage to the mice skin, the same dosage of 207nm Far-UVC light produced results that were not statistically distinguishable from the zero UV exposure controls.
207nm light is within the Far-UVC range (200nm to 230nm).The study concluded that filtered Far-UVC light kills bacteria efficiently but does not appear to be significantly cytotoxic or mutagenic to human cells.
