A specific wavelength of UV light can curb COVID-19 spread

It is also safer for use in public spaces.


Effective disinfection technology to combat SARS-CoV-2 can help reduce viral transmissions. Ultraviolet (UV) devices emitting UVC irradiation have proven to be effective for virus disinfection. However, there is minimal information available for SARS-CoV-2 due to the safety requirements of testing.

A new study by the CU boulder suggests that a specific wavelength of Far ultraviolet-C, at 222 nanometers, of ultraviolet (UV) light, is extremely effective at killing the virus. It is also safer to use in public.

The study highlights UV light used as a game-changer. It could also lead to new affordable, safe, and highly effective systems for reducing viral spread in crowded public spaces like airports and concert venues.

Senior author Karl Linden, professor of environmental engineering, said, “Of almost every pathogen we have ever studied, this virus is one of the easiest, by far, to kill with UV light. It takes a very low dose. This indicates that UV technology could be a perfect solution for protecting public spaces.”

In most forms, UV light is harmful to live beings. Once absorbed by an organism’s genome, it ties knots in it and prevents it from reproducing.

Some products use human-engineered UV light, but a white phosphorous coating on the inside protects people from the UV rays. Taking that coating off makes them harmful for our skin and our eyes. At the same time, they can kill pathogens.

The new findings are unique because they hit the sweet spot between UV light that is relatively safe for humans and harmful for viruses, especially the one that causes COVID-19.

For the study, scientists compared different UV wavelengths side-by-side. They used other standardized methods across the UV light industry.

Linden, said, “We thought, let’s come together and make a definitive statement on what UV exposure is required to kill off SARS-CoV-2. We wanted to make sure that if UV light is being used to control disease, you’re delivering the right dose that’s protective of human health and human skin, but also going to be killing off these pathogens.”

Scientists found that the virus was quite susceptible to UV light in general, a specific wavelength of Far ultraviolet-C, at 222 nanometers, was particularly effective. Not only is it safe, but it’s also the most effective.

Scientists noted, “This safer wavelength of Far UV-C light could serve as a key mitigation measure against the current and future pandemics, in addition to improved ventilation, mask-wearing, and vaccination.”

Journal Reference:

  1. Ben Ma et al. UV Inactivation of SARS-CoV-2 across the UVC spectrum: KrCl* excimer, mercury-vapor, and LED sources. DOI: 10.1128/AEM.01532-21
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