Ultraviolet light has been used for decades to stop pathogens in their tracks. But does it work against SARS-CoV-2, the virus behind the pandemic?
The short answer is yes. But you need the right kind of UV in the right dosage, a complex operation that is best performed by trained professionals. In other words, many home UV devices that claim to kill SARS-CoV-2 are probably not a safe choice.
UV radiation can be divided into three types based on the wavelength: UVA, UVB and UVC. Almost all of the UV radiation that reaches the earth is UVA, since most of the UVB and all UVC light is absorbed by the ozone layer Centers for disease control and prevention. And it̵
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“UVC has been used for years, it’s not new,” Indermeet Kohli, a physicist who studies dermatology photomedicine at Henry Ford Hospital in Detroit, told Live Science. UVC at a specific wavelength of 254 nanometers has been successfully used to inactivate H1N1 influenza and others Corona viruseshow severe acute respiratory virus (SARS-CoV) and Middle Eastern respiratory syndrome (MERS-CoV), she said. A study published in the Preprint database on June 26th medRxiv from Kohli’s colleagues, who are waiting for peer review, now confirms that UVC also eliminates SARS-CoV-2.
UVC-254 works because this wavelength causes lesions in DNA and RNA. Sufficient exposure to UVC-254 will damage the DNA and RNA so that they cannot replicate, effectively kill, or inactivate a microorganism or virus.
“The data that supports this technology, the ease of use and the non-contact nature of UVC make it a valuable tool in the midst of the pandemic,” said Kohli. However, responsible and accurate use is vital. UVC’s DNA-damaging properties make it extremely dangerous for human skin and eyes, Kohli said. She warned that UVC disinfection technologies should primarily be left to medical institutions and should be evaluated for safety and effectiveness by teams with expertise in photomedicine and photobiology.
When it comes to UVC lamps at home, their ability to damage the skin and eyes isn’t the only danger, said Dr. Jacob Scott, a research doctor in the translational hematology and oncology research department of the Cleveland Clinic. These devices also have low quality control, which means that there is no guarantee that you will actually eliminate the pathogen, he said.
“UVC kills the virus, but the problem is that you need to get an adequate dose,” Scott told Live Science. “Especially for porous N95 masks, a fairly large dose of UVC-254 nm is required” to eliminate SARS-CoV-2. This accuracy is not possible with home devices.
In hospitals, the geometry of the room, shadow formation, timing and type of material or object to be disinfected are taken into account when experts determine the correct UVC dosage that is required to kill pathogens. But this kind of “quality assurance is really difficult in the world, out in the wild,” said Scott. Home appliances do not offer this precision, so using them could offer a false guarantee that SARS-CoV-2 would have been eliminated if not, he noted. “Having something that you think is clean but not is worse than something that you know is dirty,” he said, because it affects your behavior towards the object.
Both Kohli and Scott and their teams are working to make UVC disinfection of personal protective equipment (PPE) such as face masks and N95 respirators more efficient. Kohlis Group advises hospitals and providers on the conversion of existing UVC devices for the decontamination of N95 breathing apparatus. Scott’s group developed a machine This can be used by smaller medical facilities and a software program that allows users to consider the geometry of the disinfection room so that staff can deliver the most effective UVC dose.
There are discussions on site about installing UVC units in ceilings to decontaminate the circulating air, Kohli said. And others are researching a different wavelength of UVC, UVC-222, or Far-UVC that may not harm human cells, she added. But that requires more research, Kohli said. Nevertheless, it is clear that “UVC is used precisely and responsibly and has enormous potential”.
Originally published on Live Science.