The researchers say that this technology represents a new way to limit the spread of “Covid-19”, compared to current control measures that involve significant changes in people’s behavior – such as adhering to closures, physical distancing, wearing masks or vaccination.
The scientists say that in contrast to the challenges of these effective and often unpopular procedures, installing Far-UVC lighting in indoor environments can be as easy as changing a light bulb, and the device’s antimicrobial efficacy is just as impressive. “Far UV rays rapidly reduce the amount of active microbes in indoor air to nearly zero, making indoor air essentially as safe as outdoor air,” says biophysicist David Brenner, of Columbia University Medical Center.
While the germicidal properties of ultraviolet C (UVC) rays have been known for decades, the radiation’s ability to cause sunburn, skin cancer and damage people’s eyes has led to strict controls on its use, with UV rays mostly restricted to sterilizing medical equipment.
However, recently, research on shorter wavelength UVA emitters (also known as krypton-chloride lamps or KrCl excimer lamps) indicates that this subset of the UV spectrum does not pose safety risks to mice or Human skin cells, while retaining the ability to kill airborne pathogens. However, current research has been largely limited to Far-UVC testing in a small-scale laboratory.
To see if the technique would be equally effective in a standard-sized room, the scientists installed five Far-UVC lamps in a 4-by-3-meter controlled bioaerosol chamber and pumped a stream of Staphylococcus aureus bacteria into the atomizer.
“The facility is a hermetically sealed room the size of a hospital room for one person where different types of building ventilation and instrumentation can be implemented to test the potential efficacy of approaches such as Far-UVC in a large-scale setting,” says environmental microbiologist Louise Fletcher, from the University of Leeds in the UK.
According to the team, Far-UVC lamps reduced up to 98.4% of pathogen load within minutes and maintained an ambient level of 92% at a level in line with International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines.
The ventilation level in the test room was set to be like a normal room at eACH, but the Far-UVC emitted 184 changes in air, which the team says outperforms any other approach to disinfecting occupied indoor spaces.
Physicist Kenneth Wood, from the University of St Andrews in the UK, says: “Our experiments yielded amazing results, far exceeding what is possible with ventilation alone.” Despite the technology’s apparent promise, researchers acknowledge that there are difficulties to overcome the potential use of Far-UVC in the real world – specifically ensuring that Far-UVC installations in indoor environments meet the correct level of radiation exposure, being effective.
Provided this balance is safely achieved, the researchers say, we might just be looking at a game-changing part of health technology here.