In a May 7 New York Times article, researchers discussed the use of ultraviolet light in combating infectious pathogens. “We have struggled in the past to see this highly effective, very safe technology fully implemented for airborne infections,” said Dr. Edward A. Nardell, a professor of global health and social medicine at Harvard Medical School. “We’ve done the studies. We know it works.”
The article notes that UV light “mangles the genetic material in pathogens — DNA in bacteria and fungi, RNA in viruses — preventing them from reproducing.” “You’ve killed it essentially,” said William P. Bahnfleth, a professor of architectural engineering at Pennsylvania State University and the head of ASHRAE’s Epidemic Task Force.
A study conducted by Hiroshima University, published in the September 2020 issue of the American Journal of Infection Control, found that using Ultraviolet C light with a wavelength of 222 nanometers, which is safer to use around humans, effectively kills SARS-CoV-2 -- the first research in the world to prove its efficacy against the virus that causes COVID-19. Other studies have shown effectiveness against other coronavirus strains, but not specifically COVID-19.
As noted above, UV light treatment can be used as a supplement to filtration, killing pathogens that escape. Daniel Jones, president of UV Resources, a UV light treatment equipment company, touted upper-air UV-C fixtures as a commercial building remedy for viral droplets: Airborne droplets containing infectious agents can remain in room air for six minutes and longer,” he said. “Scientists have found that COVID-19 can remain infectious on surfaces at room temperature for up to nine days. Upper-air UV-C fixtures can destroy those microbes when they are exposed to the UV-C energy in a matter of seconds.” He pointed to kill ratios of up to 99.9 percent on a first-pass basis that have been modeled, and concentrations are further reduced each time the air circulates.