Special Ultraviolet Light Could Be Used to Inactivate Coronaviruses

Special ultraviolet light could be used to inactivate the coronavirus which causes COVID-19 in public places, say scientists who tested it on the germ's relatives.

Certain wavelengths of UV light can kill viruses, but are no good for preventing the spread of pathogens in humans as they harm our skin and eyes. However, what is known as far-UVC light can kill viruses and is safe for humans.

SARS-CoV-2, the bug which causes COVID-19 and has sickened over 9.6 million people according to Johns Hopkins University in the past six months, is a member of the large coronavirus family of pathogens. Other coronaviruses include SARS-CoV, which was behind the SARS outbreak almost 20 years ago, and MERS-CoV, which emerged in 2012 and causes MERS. Coronaviruses can also trigger some common colds.

The authors of the paper published in the journal Scientific Reports replicated coughs and sneezes by spritzing aerosol droplets of two common cold-causing coronaviruses (HCoV-229E and HCoV-OC43) into a chamber exposed to different concentrations of far-UVC light. They found the light inactivated 99.9 percent of the viruses.

As coronaviruses that affect humans have similarities, the team believes the light would have the same effect on other family members, such as SARS-CoV-2.

Lead author David Brenner, professor of radiation biophysics at Columbia University Vagelos College of Physicians and Surgeons, told Newsweek: "In our subsequent ongoing studies we have found that the coronavirus that causes COVID-19 is killed in just the same way by far-UVC light. These are the first studies showing that UV light, and in particular far-UVC light, is very good at killing coronaviruses."

Exposing public spaces to far-UVC light within the existing regulatory limits would inactivate around 90 percent of viruses in about eight minutes, and 99.9 percent in around 25 minutes, according to the researchers. Using low doses of far-UVC light in indoor public spaces like hospitals, on transport, in restaurants, airports and schools could be a safe and cheap way to reduce the spread of viruses including SARS-CoV-2, the team said.

Brenner said in a statement: "Since SARS-CoV-2 is largely spread via droplets and aerosols that are coughed and sneezed into the air it's important to have a tool that can safely inactivate the virus while it's in the air, particularly while people are around."

However, Brenner told Newsweek: "We don't see far-UVC light as an alternative to masks and social distancing. We see it as a new extra weapon that we can use in the battle against COVID-19. We need all the weapons we can get."

The U.S. Centers for Disease Control and Prevention states the best ways to prevent the spread of SARS-CoV-2 include washing our hands for at least 20 seconds frequently or using hand sanitizer, and avoiding touching the eyes, nose and mouth with unwashed hands. Staying at least six feet from those outside one's household, and keeping that far from those who are sick in one's home are also important.

Kenny Wood, lecturer in the School of Physics and Astronomy at the U.K.'s University of St Andrews who did not work on the paper, told Newsweek the findings are "extremely important" because they confirm far-UVC light can destroy coronaviruses.

Wood and colleagues have previously shown that far-UVC light can't penetrate the skin, and are setting up trials to test their safety around people.

"When their safety is demonstrated by in-person trials I hope that far-UVC lamps can be installed in public places," said Wood. "Taken together with other safety measures (distancing, cleanliness, etc) I believe that far-UVC lamps can go a long way to helping our lives return to normal."

Wood said far-UVC lamps can't currently be bought for the home, and he wouldn't recommend their use even if they were.

This article has been updated with comment from Kenny Wood and David Brenner.

Correction 7/3/20: This piece originally incorrectly stated the researchers used wavelengths above the legal limit for their study. The study was designed to see if exposing airborne coronaviruses to far-UVC light within the regulatory limits for exposure would be effective, and confirmed the hypothesis.

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A stock image shows a UV light bulb used to disinfect water. Getty Images