In a recent study at Columbia University, a new type of ultraviolet light (far-UVC) that appears to be safe for people in indoor settings, took less than five minutes to reduce the level of indoor airborne microbes by more than 98%. Even as microbes were continuously sprayed into the room, the level remained very low as long as the lights were on.
The study suggests that far-UVC light from lamps installed in the ceiling could be a highly effective passive technology for reducing person-to-person transmission of airborne-mediated diseases, such as COVID and influenza, indoors, and lowering the risk of the next pandemic. Far-UVC light has a shorter wavelength than conventional germicidal UVC, and studies from around the world suggest it is unable to penetrate into skin cells or eye cells.
“Far-UVC rapidly reduces the amount of active microbes in the indoor air to almost zero, making indoor air essentially as safe as outdoor air,” says David Brenner, PhD, director of the Center for Radiological Research at Columbia University . “Using this technology in locations where people gather together indoors could prevent the next potential pandemic.”
“Far-UVC light is simple to install, it’s inexpensive, it doesn’t require people to change their behavior, and evidence from multiple studies suggests it may be a safe way to prevent the transmission of any virus, including the COVID virus and its variants, as well as influenza and also any potential future pandemic viruses,” Brenner says.
Scientists have known for decades that a type of ultraviolet light known as UVC light rapidly kills microbes, including bacteria and viruses. But conventional germicidal UVC light cannot be used directly to destroy airborne viruses in occupied indoor spaces because it is a potential health hazard to the skin and eyes. Disinfecting indoor air with far-UVC light is a new approach to safely and efficiently destroy.
About a decade ago, Columbia University scientists proposed that a different type of UVC light, known as far-UVC light, would be just as efficient at destroying bacteria and viruses but without the safety concerns of conventional germicidal UVC. In the past decade, many studies have also shown that far-UVC is efficient at destroying airborne bacteria and viruses, which are much smaller than human cells. But until now these studies had only been conducted in small experimental chambers, not in full-sized rooms mimicking real-world conditions. The new study confirms that far-UVC is highly effective and safe to use in a real room environment.
“Previous studies have shown that far-UVC light can kill the COVID virus, other human coronaviruses, influenza, and drug-resistant bacteria,” Brenner says. “What’s particularly attractive about far-UVC technology as a practical method of preventing indoor disease transmission is that it will be equally good at inactivating all future COVID variants, as well as new infectious viruses that have yet to emerge, while retaining efficacy against ‘old fashioned’ viruses like influenza and measles.”
Finally, because of the way ultraviolet light kills microbes, viruses and bacteria cannot develop resistance as they do with vaccines and drug treatments.