Disinfection of indoor air with remote UVC light is a new way to safely and effectively destroy airborne viruses in occupied spaces.
Research has suggested that remote UVC light from ceiling-mounted lamps could be a highly effective passive technique to reduce the infectivity of airborne diseases and reduce the risk of a subsequent pandemic.
“Far-UVC rapidly reduces the amount of active microbes in indoor air to almost zero, making indoor air essentially as safe as outdoor air,” said David BrennerPhD, Director of the Radiology Research Center at Columbia University Vagelos College of Physicians and Surgeons and co-author of the study.
“Using this technology in places where people congregate indoors could prevent the next possible pandemic,” he added.
“Far-UVC light is easy to install, it is affordable, it does not require people to change their behavior and above all it is a safe way to prevent the spread of the virus, including COVID and its variants as influenza and also as possible future pandemic viruses,” he concluded.
Scientists have known for decades that ultraviolet light, known as UVC light, quickly kills microbes, including bacteria and viruses. However, traditional bactericidal UVC light cannot be used to directly destroy airborne viruses indoors because it can be dangerous to the skin and eyes.
About a decade ago, researchers at Columbia University suggested that a different type of UVC light, known as remote UVC light, would be just as effective at killing bacteria and viruses, but without the safety concerns of conventional bacteria that kill bacteria.
Remote UVC light is safe for humans because it has a shorter wavelength than conventional bactericidal UVC, so it cannot penetrate living human skin cells or eye cells. But it is just as effective at killing bacteria and viruses that are much smaller than human cells.
Over the past decade, many studies around the world have shown that remote UVC is both effective in killing airborne bacteria and viruses and safe to use in the vicinity of humans. But until now, these studies had been conducted only in small test chambers, not in full-size rooms that mimicked real conditions.
In this study, researchers at the University of St. Andrews, the University of Dundee, the University of Leeds and Columbia tested the effectiveness of far UVC light in a large room-sized chamber with the same ventilation rate as a regular home or office (about three ventilations per hour).
During the experiment, the nebulizer continuously sent an aerosol mist of S. aureus into the room. (This microbe was chosen because it is slightly less sensitive to far UVC light than coronaviruses, providing researchers with a suitable conservative model.) As the concentration of microbes in the room stabilized, the researchers turned on commercially available remote UVC lamps. .
At a intensity based on the current limit on exposure to far UVC light exposure set by the American Conference of Governmental Industrial Hygienists, far UVC lamps inactivate more than 98 percent of the microbes in the air in just five minutes. The low number of viable microbes was maintained over time, although microbes were still sprayed into the room.
The effectiveness of different approaches to reducing indoor viral load is usually measured by equivalent ventilation per hour. In this study, remote UVC lamps produced 184 equivalents of ventilation per hour. This surpasses all other methods of disinfecting populated interiors, where 5-20 equivalents of ventilation per hour is the best that can be achieved in practice.
“Our experiments yielded spectacular results that far exceeded what is possible with ventilation alone,” said Kenneth WoodPhD, lecturer in the Department of Physics and Astronomy at St. Andrews University and senior author of research.
“To prevent the spread of airborne diseases, remote UVC lights could make an indoor as safe as an outdoor golf course on a windy day in St. Andrews,” he added.
“Previous studies have shown that far-reaching UVC light can kill COVID virus, other human coronaviruses, influenza, and drug-resistant bacteria,” Brenner noted.
“As a particularly attractive practical method in remote UVC technology to prevent the spread of indoor diseases, it is equally good to inactivate all future variants of COVID as well as new infectious viruses that have not yet emerged but retain their efficacy against ‘old-fashioned’ viruses, such as influenza and measles, “he added.
“Finally, because ultraviolet light kills microbes, viruses and bacteria cannot develop resistance like with vaccines and medications,” he concluded.
Source: ANI