Far-UVC Light Kills 99.9% of Airborne Coronaviruses Within 25 Minutes in New Study

A new study has found that more than 99.9% of seasonal coronaviruses present in airborne droplets were killed when exposed to a particular wavelength of ultraviolet light that is safe to use around humans.

Researchers at Columbia University Irving Medical Center (New York, NY, USA) have been investigating far-UVC light (222 nm wavelength) to continuously and safely disinfect occupied indoor areas. Conventional germicidal UVC light (254 nm wavelength) can be used to disinfect unoccupied spaces such as empty hospital rooms or empty subway cars, but direct exposure to these conventional UV lamps is not possible in occupied public spaces, as this could be a health hazard. On the other hand, far-UVC light cannot penetrate the tear layer of the eye or the outer dead-cell layer of skin and so it cannot reach or damage living cells in the body. The researchers had previously shown that far-UVC light can safely kill airborne influenza viruses.

In their study, the researchers used a misting device to aerosolize two common coronaviruses. The aerosols containing coronavirus were then flowed through the air in front of a far-UVC lamp. After exposure to far-UVC light, the researchers tested to see how many of the viruses were still alive. The researchers found that more than 99.9% of the exposed virus had been killed by a very low exposure to far-UVC light. Based on their results, the researchers estimate that continuous exposure to far-UVC light at the current regulatory limit would kill 90% of airborne viruses in about eight minutes, 95% in about 11 minutes, 99% in about 16 minutes, and 99.9% in about 25 minutes. The sensitivity of the coronaviruses to far-UVC light suggests that it may be feasible and safe to use overhead far-UVC lamps in occupied indoor public places to markedly reduce the risk of person-to-person transmission of coronaviruses, as well as other viruses such as influenza.

“Based on our results, continuous airborne disinfection with far-UVC light at the current regulatory limit could greatly reduce the level of airborne virus in indoor environments occupied by people,” says the study’s lead author David Brenner, PhD, Higgins Professor of Radiation Biophysics at Columbia University Vagelos College of Physicians and Surgeons and director of the Center for Radiological Research at Columbia University Irving Medical Center.

“Because it’s safe to use in occupied spaces like hospitals, buses, planes, trains, train stations, schools, restaurants, offices, theaters, gyms, and anywhere that people gather indoors, far-UVC light could be used in combination with other measures, like wearing face masks and washing hands, to limit the transmission of SARS-CoV-2 and other viruses,” added Brenner.

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Columbia University Irving Medical Center