Researchers from Hiroshima University, Japan, have completed the first study documenting the utility of 222 nm far-ultraviolet light (UVC) in deactivating SARS-CoV-2, the causative agent of COVID-19, on surfaces.

Most UV disinfection systems use germicidal lamps emitting 254 nm UVC, a wavelength that is harmful to skin Researchers showed that 222 nm UVC light, which does not harm human eye and skin cells, effectively kills SARS-CoV-2. Source: Hiroshima UniversityResearchers showed that 222 nm UVC light, which does not harm human eye and skin cells, effectively kills SARS-CoV-2. Source: Hiroshima Universityand eyes and typically used to sanitize empty rooms. The same germicidal action is demonstrated by the 222 nm wavelength, which has been shown to deactivate other coronavirus types and is safer for deployment around people.

The researchers applied a 100 microliter solution containing the virus to a 9 cm sterile polystyrene plate, which was then exposed to a 222-nm krypton-chloride excimer lamp module placed 24 cm above its surface. A 99.7% reduction in viable SARS-CoV-2 was achieved after 30 seconds of treatment with UVC at 0.1 mW/cm2.

The research published in the American Journal of Infection Control indicates that a 222-nm UVC disinfection system could be used in occupied public spaces. However, additional evaluations of the safety and efficacy of this irradiation technology are warranted.

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