Claims for using UV in Air filtering units to fight Covid-19 dismissed by science
While using Ultraviolet light has been used to stop pathogens like Covid-19, its effective use requires dosage controls that are not possible in typical air cleaning units. In addition, Ultraviolet light when improperly used can be extremely dangerous to human skin and eyes.
Research from Consumer Reports indicates that there is no evidence to prove that UV light in home use and commercial grade air purifiers kills the Covid-19 virus.
“Some air purifiers claim to kill viruses using UV light or some kind of photocatalysis technology,” says John Galeotafiore, a director of testing at CR. “We suggest consumers take these claims with a grain of salt because there isn’t enough concrete evidence yet that proves they work in these settings.”(1)
Research from Live Science indicates that very specific and controlled use in medical settings is effective.
Ultraviolet light has been used to eliminate pathogens for decades and is effective against SARS-CoV-2, the virus behind the pandemic.
But it takes the right kind of UV in the right dosage, a complex operation that is best administered by trained professionals. In other words, many at-home UV-light devices claiming to kill SARS-CoV-2 likely aren’t a safe bet.
“UVC has been used for years, it’s not new,” Indermeet Kohli, a physicist who studies photomedicine in dermatology at Henry Ford Hospital in Detroit, told Live Science. UVC at a specific wavelength, 254 nanometers, has been successfully used to inactivate H1N1 influenza and other coronaviruses,(2) such as severe acute respiratory virus (SARS-CoV) and Middle Eastern Respiratory Syndrome (MERS-CoV), she said. A study published June 26 to the preprint database medRxiv from Kohli’s colleagues awaiting peer review now confirms that UVC also eliminates SARS-CoV-2.
UV radiation can be classified into three types based on wavelength: UVA, UVB and UVC. Nearly all the UV radiation that reaches Earth is UVA, because most of UVB and all of UVC light is absorbed by the ozone layer, according to the Centers for Disease Control and Prevention. And it’s UVC, which has the shortest wavelength and the highest energy, that can act as a disinfectant.
“The data that backs up this technology, the ease of use, and the non-contact nature” of UVC make it a valuable tool amid the pandemic, Kohli said. But responsible, accurate use is critical. UVC’s DNA-damaging capabilities make it extremely dangerous to human skin and eyes, Kohli said. She cautioned that UVC disinfection technologies should primarily be left to medical facilities and evaluated for safety and efficacy by teams with expertise in photomedicine and photobiology.
When it comes to a-home UVC lamps, their ability to damage skin and eyes isn’t the only danger, Dr. Jacob Scott, a research physician in the Department of Translational Hematology and Oncology Research at Cleveland Clinic, said. These devices also have low-quality control, which means there’s no guarantee that you’re actually eliminating the pathogen, he said.
“UVC does kill the virus, period, but the issue is you have to get enough dose,” Scott told Live Science. “Particularly, for N95 masks, which are porous, it takes a pretty big dose” of UVC-254 nm to eliminate SARS-CoV-2. This kind of accuracy isn’t possible with at-home devices.
In hospitals, the geometry of the room, shadowing, timing and the type of material or object being disinfected are all accounted for when experts determine the right dosage of UVC needed to kill pathogens. But that kind of “quality assurance is really hard out in the world, out in the wild,” Scott said. At-home devices don’t offer that kind of precision, so using them could offer a false assurance that SARS-CoV-2 has been eliminated when it hasn’t, he noted. “Having something 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.(3)