Can coronavirus be killed by UV mild?

A new research study shows that a safe UV disinfection system is effective in killing the coronavirus.

Recent studies have reported that SARS-CoV-2 can survive on surfaces for several days and that hospitals can be a potential source of transmission due to contaminated surfaces. With the aim of slowing the spread of COVID-19, a recent study examined the effectiveness of UV disinfection on surfaces contaminated with SARS-CoV-2.

UV disinfection systems are increasingly used in healthcare to help prevent the spread of healthcare-related infections. They most commonly emit UV radiation C (UVC) of around 254 nm – but this is harmful to the skin and eyes. Previous studies have shown that 222 nm UVC light, which belongs to far UVC (207-222 nm), is less harmful but has the same disinfecting properties. Even so, previous studies with 222 nm UVC light only looked at how it can kill other seasonal coronaviruses, not directly on SARS-CoV-2.

Hiroshima University researchers, published in the American Journal of Infection Control, conducted a study using Ushio's Care222TM krypton chloride excimer lamp. Sterile polystyrene plates were covered with a 100 microliter solution containing the coronavirus. After drying in a biosafety cabinet at room temperature, a Far UVC lamp was placed 24 centimeters above the surface of the plates. The radiation intensity at the surface was 0.1 mW / cm². After treatment, the plates were analyzed for the presence of live virus.

The study reported that 99.7% of the SARS-CoV-2 coronavirus was killed after 30 seconds of exposure to 222 nm UVC radiation at 0.1 mW / cm².

The 254 nm germicidal UVC lamps currently used to disinfect healthcare facilities are harmful to the skin and eyes. This means that they can only be used in an empty room. A wavelength of 222 nm UVC is much safer and does not harm the skin and eyes like the wavelength of 254 nm. The researchers suggest that a 222 nm UVC disinfection system could be used safely in occupied public spaces.

This study is a positive step forward in slowing the spread of SARS-CoV-2 through prevention and control practices such as UV disinfection. However, the researchers note that more studies are needed to assess the safety and effectiveness of 222nm UVC exposure in killing SARS-CoV-2 viruses on surfaces in real-world environments.

Written by Helen Massy, ​​BSc

References:

Kitagawa, H., Nomura, T., Nazmul, T., Omori, K., Shigemoto, N., Sakaguchi, T. and Ohge, H., 2020. Effectiveness of 222 nm ultraviolet light in disinfecting SARS-CoV – 2 surface pollution. American Journal of Infection Control.

EurekAlert !. 2020. Study shows first evidence that safer UV light is effective in killing viruses that cause COVID-19. (online) Available at: (Accessed September 21, 2020).

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