Ultraviolet lights intended to destroy the coronavirus could be installed in bathrooms or elevators at offices, switching on whenever a person leaves. The lights could also click on in empty office hallways or blaze away unseen inside a building’s ventilation ducts. Smaller lights could even be trained continuously on much-used elevator buttons.
Those are some of the ideas suggested by a team led by researchers from the Institute of Photonic Sciences in Spain. Their Perspective article was published recently in the journal ACS Nano.
The researchers suggested that a type of ultraviolet light known as UVC light, by destroying the virus on surfaces or in the air, could make indoor spaces like offices safer as the world economy moves to reopen.
UVC light is “a promising candidate,” the study said. “We advocate the widespread use of UV-C light as a short-term, easily deployable, and affordable way to limit virus spread in the current SARS-CoV-2 pandemic.”
UVC light is one of three types of ultraviolet radiation. The others are UVA and UVB. UVC is considered the most damaging type. Fortunately, natural UVC light doesn’t reach the Earth, thanks to the ozone layer and atmosphere. But the light can be made by various manmade sources. The researchers noted that UVC light can produce eye damage and “carcinogenic effects.” Federal experts have said it is “reasonably anticipated to be a human carcinogen.”
Scientists believe that UVC light can probably kill the coronavirus. It is already commonly used in water disinfection, and its use has been proven to reduce air transmission of tuberculosis and airborne viruses, researchers said. It’s been used in hospitals, homeless shelters, and airports.
Because of the dangers of the light, UVC sources could be “distributed with no direct optical path to humans in the ducts of ventilation systems” to kill the coronavirus, the researchers suggested in the article. Or the light could be aimed straight across the ceiling or the floor, with circulating air getting irradiated as it passes through the beams, though this would require a “careful analysis of potentially hazardous stray light.” Stand-alone air cleaners could pass air through a gantlet of UVC light.
UVC lights could also come on in toilets, elevators, and office pantries when people leave. And elevator buttons or handrails could be continuously exposed to weaker UVC light because people only use them momentarily, researchers suggested.
The US Centers for Disease Control and Prevention already recommends that building owners, in addition to taking steps such as increasing fresh air in their ventilation systems and improving filtering, “consider using ultraviolet germicidal irradiation (UVGI) as a supplement to help inactivate the virus.”
“Fundamentally, I agree with the premise that UV has great potential for reducing COVID transmission,” Dr. Edward A. Nardell, a professor of global health and social medicine at Harvard Medical School, said in an e-mail. But he disagreed with the researchers in some respects, including their interest in using UV light in ventilation ducts.
He said the “upper room” irradiation technique, which shines ultraviolet light near the ceiling, “where applicable, is much more efficient,” irradiating much larger volumes of air than practicable with the air passing through ducts.
The researchers from the Spanish institute estimated that a “global investment of a few billion dollars” could protect somewhere around 1 billion indoor workers worldwide.
“However, the global market for UV-C light barely reaches one billion dollars per year currently, so it may have difficulty coping with the expected rise in demand originated by the SARS-CoV-2 pandemic,” the researchers noted.
“We argue that additional measures are necessary to reduce virus transmission when people resume attending schools and jobs that require proximity or some degree of physical contact. Among the available alternatives, UV-C light satisfies the requirements of rapid, widespread, and economically viable deployment. Its implementation is only limited by current production capacities, an increase of which requires swift intervention by industry and authorities,” the researchers argued.
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