More than 99.9% of seasonal coronaviruses present in airborne droplets died when exposed to a particular wavelength of ultraviolet light that is safe to use around humans, a new study has found at the Irving Medical Center of the Columbia University.
“Based on our results, continuous airborne disinfection with far-flung UV light at the current regulatory limit could greatly reduce the level of airborne viruses in human-occupied indoor environments,” says study lead author David Brenner, PhD, Higgins Professor of Radiation Radiophysics at Columbia University College of Physicians and Surgeons Vagelos and director of the Radiation Research Center at Irving Medical Center at Columbia University.
The research was published today in Scientific Reports.
Conventional germicidal UVC light (254nm 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 busy public spaces, as This could be a health hazard.
To continuously and safely disinfect occupied interior areas, researchers at Columbia University Irving Medical Center have been investigating far UVC light (222nm wavelength). Far UVC light cannot penetrate the tear layer of the eye or the outer layer of dead skin, so it cannot reach or harm living body cells.
The researchers had previously shown that far UVC light can safely kill flu viruses in the air.
The new document extends its research to seasonal coronaviruses, which are structurally similar to the SARS-CoV-2 virus that causes COVID-19.
In the study, the researchers used a nebulization device to aerosolize two common coronaviruses. Aerosols containing coronaviruses were flowed through the air in front of a distant UVC lamp. After exposure to distant 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 removed by very low exposure to far UVC light.
Based on their results, the researchers estimate that continued exposure to far ultraviolet light at the current regulatory limit would kill 90% of viruses in the air in about 8 minutes, 95% in about 11 minutes, 99% in about 16 minutes and 99.9% in about 25 minutes
Use of far UVC light in busy interior spaces
The sensitivity of coronaviruses to far ultraviolet light suggests that it may be feasible and safe to use far ultraviolet light bulbs in busy indoor public places to greatly reduce the risk of person-to-person transmission of coronavirus, as well as other viruses such as influenza.
Ongoing studies in SARS-CoV-2
In another ongoing study, researchers are testing the efficacy of far UVC light against SARS-CoV-2 in the air. Preliminary data suggests that far UVC light is just as effective in killing SARS-CoV-2.
“Far UVC light doesn’t really discriminate between coronavirus types, so we expected it to kill SARS-CoV-2 in the same way,” says Brenner. “Since SARS-CoV-2 is largely transmitted through droplets and aerosols that are coughed and sneezed into the air, it is important to have a tool that can safely inactivate the virus while it is in the air, especially when people are around. “
Brenner continues: “Because it is safe to use in busy spaces such as hospitals, buses, airplanes, trains, train stations, schools, restaurants, offices, theaters, gyms, and anywhere people gather indoors, the Far UV light could be used in combination with other measures, such as wearing face masks and washing hands, to limit the transmission of SARS-CoV-2 and other viruses. “
Manuela Buonanno, David Welch, Igor Shuryak, David J. Brenner. Far UVC light (222 nm) efficiently and safely inactivates human coronaviruses in the air. Scientific reports, 2020; 10 (1) DOI: 10.1038 / s41598-020-67211-2
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