Does UV Light Kill The New Coronavirus?

August 18, 2020

UV light has been used for decades to stop the growth of pathogens. But is it effective against SARS-CoV-2 (the virus behind the epidemic)?

In short, the answer is yes. But it requires the right UV and the right dose, a complex operation that is best administered by a trained professional. In other words, many home UV devices that claim to kill SARS-CoV-2 may not be safe.

Ultraviolet radiation can be divided into three types based on wavelength.UVA, UVB, and UVC.Almost all of the UV radiation that reaches the earth is UVA because, according to the Centers for Disease Control and Prevention, most UVB and all UVC light is absorbed by the ozone layer. And UVC has the shortest wavelength and highest energy to disinfect.

Indermeet Kohli, a physicist who studies photomedicine in the dermatology department at Henry Ford Hospital in Detroit, told Live Science, “UVC has been used for many years and it’s not new.” She said UVC at a specific wavelength of 254 nanometers has been used successfully to inactivate H1N1 influenza and other coronaviruses such as severe acute respiratory virus (SARS-CoV) and Middle East respiratory syndrome (MERS-CoV).A study published June 26 in the preprint database medRxiv, awaiting peer review from Kohli’s colleagues, now confirms that UVC also It eliminates SARS-CoV-2.

UVC-254 works because this wavelength causes lesions to DNA and RNA. Sufficient exposure to UVC-254 destroys DNA and RNA so that they cannot replicate, effectively killing or inactivating the microbe or virus.

“The data supporting this technology, the ease of use, and the non-exposure quality of UVC” make it an invaluable tool in a pandemic, Kohli said. But responsible and accurate use is essential, Kohli said, noting that UVC’s ability to destroy DNA makes it extremely dangerous to human skin and eyes. She cautioned that UV disinfection technology should be left primarily to healthcare providers and evaluated for safety and efficacy by teams with expertise in photomedicine and photobiology.

Dr. Jacob Scott, a research physician in the Cleveland Clinic’s Translational Hematology and Oncology Research Unit, said that when it comes to home UV lamps, their ability to damage the skin and eyes is not the only danger. These devices also have low quality control, which means there’s no guarantee that you’re actually eliminating pathogens, he says.

“UV does kill viruses, period, but the problem is that you have to get an adequate dose,” Scott told Live Science. “In particular, for the N95 mask, which is porous, it takes a fairly large dose” of UVC-254 nanometers to eliminate SARS-CoV-2. That kind of accuracy is impossible to achieve with home devices.

In hospitals, the geometry of the room, the shadows, the time of day, and the type of material or object being sterilized all have to be taken into account when experts determine the correct UV dose needed to kill the pathogen. But such “quality assurance is really difficult out in the field,” says Scott. He points out that household devices don’t provide that kind of precision, so using them can provide a false assurance that SARS-CoV-2 has been eradicated, which is not the case.” Having something that you think is clean, but it’s not, is worse than something that you know is dirty” because it affects your behavior toward that object, he said.

Both Kohli and Scott and their teams are working to make UV disinfection of personal protective equipment (PPE), such as face masks and N95 respirators, more effective.Kohli’s group advises hospitals and providers on repurposing existing UVC equipment for N95 respirator decontamination. Scott’s group has developed a machine that can be used in small healthcare facilities and a software program that helps users consider the geometry of the sterilization room so that staff can deliver the most effective UV dose.

Kohli said the field is having conversations about installing UVC devices in ceilings to purify circulating air. She added that others are working on another wavelength of UVC, called UVC-222 or Far-UVC, which may not damage human cells. But that requires more research, Kohli said. Still, it’s clear that “used accurately and responsibly, UVC has tremendous potential.”