Real-World Proof that Far-UVC Disinfection Works

Groundbreaking experiment neutralizes 98% of airborne pathogens in less than five minutes....

We’ve waited two years for conclusive scientific data on how effective far-UVC light may be in preventing viral infections in groups of people mingling indoors. And now we have an answer: in a recent real-world test conducted by world-renowned researchers, far-UVC lights neutralized 98 percent of airborne pathogens in an 11-by-14-foot room in less than five minutes. And even as they continued to spray pathogens into the room, the far-UVC lights constantly and proactively disinfected the entire air space.

Figure 1 Source: Nature Scientific Reports

Two years ago, as the Covid-19 pandemic was spinning out of control, Professor David Brenner of Columbia University rocked the prevention world with a research study published in Nature Scientific Reports: Far-UVC Light (222nm) Efficiently and Safely Inactivates Airborne Human Coronaviruses. The research demonstrated that while disinfection with far-UVC light is as effective as conventional UVC light in deactivating airborne pathogens, it is safer to use around people.

The 2020 report found that, unlike UVC light with longer wavelengths, which can harm skin and eyes, short-wavelength far-UVC light doesn’t penetrate live human cells. Therefore, it can be used in places where people gather to deactivate viruses in the air before you breathe them in. The report made it clear that far-UVC light has the revolutionary potential to nip Covid virus transmission—and future pandemics—in the bud.

How Effective is Far-UVC Light in Preventing Infections in Occupied Spaces?

Encouraging as it was, Dr. Brenner’s original safety study raised an important subsequent question: to what degree can far-UVC light lessen viral loads and prevent coronavirus transmission in occupied spaces? Is it possible to imagine that far-UVC light could disinfect public spaces so completely that it would actually eliminate the spread of viruses? Since then, epidemiologists, prevention experts, and health providers have been waiting for answers based on real-world data.

Last week, Dr. Brenner and teams of researchers from the University of St. Andrews, University of Dundee, and University of Leeds delivered an answer, rocking the world again with results of their latest study published in Scientific Reports. In their controlled experiment, a room-sized enclosure was equipped with five far-UVC lamps embedded in the ceiling (Figure 1). Ventilation was carefully controlled, providing three air changes per hour, the average ventilation rate in most homes.

A sprayer continuously emitted an aerosol mist of S. aureus bacteria into the room. The researchers chose that microbe because, like coronavirus, it is neutralized by far-UVC light. But because it is slightly less sensitive to far-UVC, it served as an appropriately conservative proxy for the coronavirus that causes Covid-19. As they continuously measured concentration of the airborne pathogen, they discovered that the lamps inactivated more than 98% of the microbes in just 5 minutes. That low level was maintained over time, even though microbes continued to be sprayed into the room.

Making Indoor Air as Safe as Outdoor Air

“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,” David Brenner, PhD, director of the Center for Radiological Research at Columbia University Vagelos College of Physicians and Surgeons and co-author of the study, said in a news release. “Using this technology in locations where people gather together indoors could prevent the next potential pandemic.”

The efficacy of different approaches to reducing indoor virus levels is usually measured in terms of equivalent air changes per hour (ACH). The researchers said that in their experiment, treatment of the air with far-UVC light produced the equivalent of 184 air exchanges per hour. This result far exceeds any other approach to disinfecting occupied indoor spaces, where 5 to 20 equivalent ACH is the best that can be achieved practically.

“Our trials produced spectacular results, far exceeding what is possible with ventilation alone,” said Kenneth Wood, PhD, lecturer in the School of Physics and Astronomy at the University of St. Andrews and senior author of the study. “In terms of preventing airborne disease transmission, far-UVC lights could make indoor places as safe as being outside on the golf course on a breezy day.”

How Much Far-UVC Light Do You Need?

The experiment used five commercial krypton chloride excimer far-UVC lamps, filtered to maintain wavelengths of less than 230 nm in the far-UVC range (Figure 2). Output power was set within threshold limit value safety guidelines for exposure to UVC light in an eight-hour workday determined by the American Conference of Governmental Industrial Hygienists (ACGIH).

Figure 2 Source: Nature Scientific Reports

The aerosol-based pathogens were injected at an air inlet on one side of the room, and sensors measured the reduction at a sample point at an air outlet on the other side of the room. Airflow was controlled at a rate of three air changes per hour to model the average ventilation in homes and offices.

The authors of the report noted that installers of far-UVC disinfection systems will need to come up a learning curve on correct installation of light sources to achieve disinfection goals. For example, to ensure that the disinfecting light reached all corners of the room, the researchers placed a diffusing material at the emission surface of the far-UVC sources within the chamber to broaden their irradiation pattern and increase far-UVC coverage. With those adjustments and correct placement of the lamps, they achieved the 98% reduction.

Coming Soon: The First Solid-State Far-UVC Light Source

As you might expect, at NS Nanotech we are tremendously excited about the results of the latest experiment from the world’s leading researchers in the U.S. and Europe. Especially as we finish development of our nitride semiconductor-based far-UVC light emitter. Our ShortWaveLight™ Emitter is the world’s first solid-state source of far-UVC light.

Our solid-state far-UVC emitter will be ideal for small rooms and personal disinfection applications. And now that we have additional verification of safety and efficacy requirements, we can tune our specs to deliver the kinds of breakthrough disinfection applications the study’s authors envision. We already have numerous initial customers in our ShortWaveLight™ Evaluation Kit Program working with prototypes of our emitters to design products for multiple vertical market applications.

It’s impossible to overstate the importance of these applications. As Dr. Brenner says in the news release: “Far-UVC light is simple to install, it’s inexpensive, it doesn’t need 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.”