Scientists studying use of UV light to fight COVID-19 spread
High up near the ceiling, in the dining room of his Seattle-area restaurant, Musa Firat recently installed a “killing zone” — a place where swaths of invisible electromagnetic energy penetrate the air, ready to disarm the coronavirus and other dangerous pathogens that drift upward in tiny, airborne particles.
Firat’s new system draws on a century-old technology for fending off infectious diseases: Energetic waves of ultraviolet light — known as germicidal UV, or GUV — are delivered in the right dose to wipe out viruses, bacteria and other microorganisms.
Research already shows that germicidal UV can effectively inactivate airborne microbes that transmit measles, tuberculosis and SARS-CoV-1, a close relative of the novel coronavirus. Now, with concern mounting that the coronavirus that causes COVID-19 may be easily transmitted through microscopic floating particles known as aerosols, some researchers and physicians hope the technology can be recruited to help disinfect high-risk indoor settings.
“I thought it was a great idea, and I want my customers to be safe,” Firat said.
UV is being used to decontaminate surfaces on public transit and in hospitals where infectious droplets may have landed, as well as to disinfect N95 masks for reuse. But so far using this technology to provide continuous air disinfection has remained outside of most mainstream, policy-setting conversations about the coronavirus.
Research shows close to 90 percent of airborne particles from a previous coronavirus (SARS-CoV-1) can be inactivated in about 16 seconds when exposed to the same strength of UV as in Firat’s restaurant’s ceiling.
“Although it’s not perfect, it probably offers the best solution for direct air disinfection” in the current pandemic, said David Sliney, a faculty member at Johns Hopkins University and longtime researcher on germicidal UV.
Germicidal UV harnesses a portion of the electromagnetic spectrum that contains short waves of radiant energy, called UV-C. This wavelength is further away from the visible spectrum than other forms of UV light.
Think of it as giving the virus a lethal sunburn.
UV can be a powerful weapon against an airborne virus, but people can still get sick from the larger, heavier droplets ejected via coughs and sneezes — what researcher Richard Corsi called the “near field.”
“In that scenario, you’re inhaling a very concentrated cloud of these tiny particles that you can’t see,” said Corsi, dean of the Maseeh College of Engineering and Computer Science at Portland
State University. “You’re getting a pretty significant dose in your respiratory system.”
So, Corsi said, face masks and social distancing are necessary.
Low-dose germicidal UV can damage the eyes and skin, but Dr. Edward Nardell, a professor at Harvard Medical School who researches GUV, said the risks of skin cancer are considered negligible, especially compared with longer wavelengths of UV that can penetrate more deeply.