Study finds a UV light that kills COVID-19 and is safe for humans

Researchers with Hiroshima University in Japan have demonstrated that a UV light wavelength safe for use around humans is also capable of killing the virus that causes COVID-19. The newly published study is the first to show that Ultraviolet C light with a 222nm wavelength (Far-UVC) is effective against SARS-CoV-2 specifically, not just similarly-structured coronaviruses that pop up seasonally and cause less extreme illnesses.

It's no secret that certain light wavelengths can kill microbes — these lights are, for example, used in some public and aircraft bathrooms to rapidly 'clean' surfaces after each use. However, the germicidal use of light often involves the wavelength 254nm, which is useful for inactivating certain viruses, but is also dangerous to human eyes and skin.

The risk this light poses to humans limits its use in public settings during operational hours, forcing the use of potentially hazardous and inconvenient chemical-based solutions. However, a growing body of evidence has implicated the safer 222nm wavelength as also effective against a number of pathogens without putting human vision and skin at risk.

This latest study is the first to prove that Far-UVC light is effective at inactivating the SARS-CoV-2 virus behind the pandemic, making it a promising solution for sanitizing public surfaces that would otherwise be difficult to disinfect on a regular basis. Such lighting systems would be particularly useful in hospital settings where it is difficult to fully empty a room for germicidal light use.

According to the researchers, the light is able to kill 99.7-percent of the SARS-CoV-2 virus after only 30 seconds. However, because this light wavelength isn't able to penetrate the protective layer on human tissues, it won't cause vision or skin damage in humans, making it a more appealing and safe alternative over the commonly used 254nm germicidal UV lights.