When Covid reached the U.S. in force earlier this year, very little was known about the novel (as in new) coronavirus that caused it, other than its aggressive transmission rate and potential lethality. Researchers know much more now, including the fact that much of its spread appears to be indoors and through droplets transmitted in the air.
This has led to some prevention breakthroughs, including one related to wellness design being researched at Columbia University Irving Medical Center. The radiation scientist leading the study is Dr. David Brenner, who has been researching how ultraviolet light works on drug-resistant bacteria long before the viral Covid arrived.
The director of the university’s Center for Radiological Research identified a wavelength called far-UVC that kills these superbugs without penetrating human skin. He shared the concept in a 2017 TED Talk. Given its potential applicability to this pandemic, Brenner and his Columbia team set out to determine whether the technology could also kill the Covid virus.
In a study published in June, the news was extremely promising: “Far-UVC Light Safely Kills Airborne Coronaviruses,” preliminary findings declared in the study headline. “Based on our results, continuous airborne disinfection with far-UVC light at the current regulatory limit could greatly reduce the level of airborne virus in indoor environments occupied by people,” Brenner reported. The full study can be read in Scientific Reports. It’s the ‘occupied by people’ proviso that’s a game-changer; most ultraviolet light is harmful to humans and used in unoccupied spaces.
Residential Far-UVC Potential
While the potential for far-UVC to render classrooms and workplaces safer is great, it can also be helpful in living spaces — particularly in shared quarters where Covid has been particularly impactful on vulnerable populations. Here is Brenner’s take on living space applications:
Jamie Gold: Do you see far-UVC light being used in residential settings (e.g., assisted living facilities, military barracks, dorms, etc.)?
David Brenner: Yes, any indoor setting where people are likely to be close together.
Gold: What types of products (e.g., bulbs, ceiling lights) have been shown to be safe and effective for dispensing far-UVC light?
Brenner: The current far-UVC technology is called an excimer light, and the idea is to install these in the ceiling of the indoor room(s) in question. Some vendors have combined far-UVC/visible light fixtures while others have “stand alone” far-UVC lights.
Gold: Do you see far-UVC light being used in single family residential settings in the next few years? If not, why not?
Brenner: In the longer term perhaps, but more immediately I see the main applications being more for more public indoor settings, where one has less knowledge of the disease status of the other people in the indoor space.
Incidentally, just as there is a move in visible lights toward LED, the same may go for far-UVC. At present, far-UVC LED lights are a bit too inefficient for large scale deployment, but I would expect that the LED manufactures will produce practical far-UVC LED lights in the near future.
Gold: Anything else you’d like to add about far-UVC light for residential-related uses?
Brenner: One plus is that far-UVC lamps would be useful to reduce not only the transmission of COVID-19 but, ongoing, also other airborne diseases such as seasonal influenza, measles and TB – not to mention the next pandemic virus when it comes. I might just add in terms of safety, that there are already national and international regulations as to how much UV light of a particular wavelength people can safely be exposed to. The far-UVC vendors are designing their lamps to stay well within these regulatory safety limits.
Gold: How high can they be to not diminish their effectiveness. For example, is a 20-foot ceiling too high?
Brenner: There is no particular limitation here. If the ceiling is higher, one either uses more lamps or more intense lamps. In this sense this is no different from designing the regular visible lighting for a room – for visible lighting, a bigger room and/or a room with a higher ceiling simply requires using more lights or higher wattage lights.
I might add that exactly the same software that lighting designers currently use to design the visible lighting for any given room has now been adapted to be used for indoor far-UVC lighting design.
An Available Alternative
As Brenner noted in his comments, this technology is not yet in wide circulation for single family residences or even individual units in multi-family spaces. Lamps Plus and Ferguson Bath, Kitchen & Lighting Galleries, both major lighting retailers, are not yet offering products with far-UVC, they shared in response to inquiries. Nor does it show up in any home center online searches. Yet. It’s likely that future searches will turn up numerous choices as the technology becomes commercialized and affordable.
Similar technologies are already available for residential installation. Big Ass Fans’ Haiku light/fan combination with upper room GUV, (germicidal ultraviolet light) is an example. “Upper-room GUV has been safely used for preventing airborne transmission for at least 70 years,” reports the Illuminating Engineering Society, a professional association for lighting technology and education in a study about UVGI, as it’s often called. “GUV refers to using ultraviolet radiant energy to inactivate bacteria, mold spores, fungi or viruses. When the process is applied in a given location, it has generally been referred to as ultraviolet germicidal irradiation (UVGI),” the study explains.
Brenner explains the difference between UVGI and far-UVC: “Both wavelengths are equally effective at killing coronaviruses, including the COVID-19 virus, but they are very different in terms of safety, specifically to the skin and eyes. Specifically people shouldn’t be directly exposed to the light from conventional germicidal UV lamps. By contrast, it is safe to continually expose the air in occupied indoor space to far-UVC light, which results in continuous killing of airborne viruses, in turn leading to a much lower risk of COViD-19 transmission.”
What manufacturers do with UGVI in fixtures like the Haiku light-fan combinations is to design the fixture so that the light is beamed away from anyone sitting or standing in the room. (There are cautions detailed in the study that relate to the safe installation and handling of these fixtures that don’t impact anyone sitting in the room when they’re mounted on a ceiling.) It is also possible that the blue light used in fixtures like these could impact circadian rhythms, so it might best be used in areas other than bedrooms.
Some firms are using UV light in residential air filtration systems, design colleagues report, but since that light is completely hidden from room occupants, it doesn’t need to have the same safety components designed into exposed fixtures.
It took more than a decade for LEDs to become cost-effective and widespread. Part of the reason for their ubiquity now is energy conservation codes, like California’s CALGreen. If Covid drives wellness design codes in the country’s largest market, (linked to awareness that future pandemics are likely too), it could help spur the development and affordability of far-UVC technology for residential, as well as commercial use, nationally and even globally.