Disinfecting With Light: Revisiting sanitizing UV-LEDs

Shutterstock / Designprax / Butusova Elena
Shutterstock / Designprax / Butusova Elena
Published On
May 14, 2021

Today’s global concern about germs and germicidal treatment makes it a fortuitous moment for disinfectant LED lighting. While it remains a nascent area as research continues, markets are broadening and companies with commercialized products are building on their successes.

“Sanitizing Light,” in the May 2019 issue of Electrical Contractor, explored antimicrobial LED lighting in the visible light spectrum. In this approach, LEDs are tuned to wavelengths between 405–425 nanometers (nm) to deactivate and inhibit bacteria, mold, mildew and fungi.

Today, you’ll find more manufacturers in the antimicrobial space, including some offering ultraviolet LED (UV-LED), a disinfectant approach that also tackles viruses.

“COVID-19 has raised our consciousness regarding germ spread. Disinfection light is getting a renewed look and renewed R&D,” said Jennifer Brons, research program coordinator for Mount Sinai Health System’s Light and Health Research Center in New York. The center, launched in February, is part of the Icahn School of Medicine at Mount Sinai. Previously, Brons was at the Rensselaer Polytechnic Institute in Troy, N.Y., and its Lighting Research Center (LRC).

In Mount Sinai’s mission to research the influence of light on mental and physical health, a focus on UV disinfection technology will be part of its efforts, building off work begun by LRC.

For the record, while UV-LED is too new, other UV-C lighting is being tested by the National Emerging Infectious Diseases Laboratories at Boston University for its ability to disable SARS-CoV-2, the virus that causes COVID-19. Manufacturer lab testing has shown SARS-CoV-2 kill rates of 99% on contaminated surfaces.

Shape-shifters

UV operates in three wavelengths: UV-A (315–400 nm), UV-B (280–315 nm) and UV-C (100–280 nm). The shorter the wavelength, the stronger its energy intensity. UV-C is the strongest and most dangerous if exposed to skin and eyes. Found in outdoor light, UV-A and UV-B are not as strong but can cause skin aging, sunburn and skin cancer.

Brons said LRC tested 12 UV disinfecting products (UV-LED, UV low-pressure discharge lamps, krypton chloride excimer discharge and others) last year. Luminaires included hybrid (UV and visible light) products, dedicated ceiling- and wall-mounted UV products, UV wands and more.

In its testing, LRC researchers selected the least expensive and most readily available UV disinfection products that were either new to the market or used in commercial settings. Testing found the UV-C wavelength to be the most effective at bacterial disinfection (roughly 1,000 times the efficacy) relative to UV-A. However, the report added, “Occupants cannot be exposed to most UV-C products without exceeding published limits for exposure. UV-A is a safer approach when virus or airborne decontamination is not the objective but must run as continuous light source.”

Some companies committed to UV-C embed the lighting into a device, thus shielding users. Others run the UV at a low input at a continuous operation.

“Our testing and responses from the industry in general showed us disinfecting light is still at the early stage,” Brons said. “UV-A LED could work well on surface decontamination. Airborne pathogens are harder to impact. We explored UV-A set between 365–424 nm.”

Brons pointed to applications for UV-LED including offices, schools and healthcare buildings where surface decontamination is a must.

“It all comes down to what pathogen you want to eliminate and how you want to approach it,” Brons said. “UV-C can be high-intensity but short duration. UV-A can be longer duration but lower intensity. When UV-LEDs become competitive, I think we will start seeing them tucked into different areas and sources. It is a question of where you put these fixtures and safely use them. You will need effective price points, too. I feel UV-LED will have an important part to play now and into the future based on their effectiveness on different pathogens.”

The smaller, the better

Oliver Lawal is president and CEO of AquiSense Technologies, Erlanger, Ky. The company opened its doors in 2015 confident in its application of UV-LED for water treatment. Today, demand is outstripping supply. Its LED disinfection products use UV-C (200–280 nm) and are designed to kill viruses, bacteria and other pathogens in water within seconds. The company is also developing applications for air and surface decontamination. Compactly designed, the UV-LEDs allow for instant, full-intensity power operation, unlimited cycling, remote start/stop and no heat transfer. These properties of LED are what may attract customers to UV-LED.

“The question isn’t, ‘Do UV-LEDS work?’ They do. But to be effective, they must be part of a successful system design,” Lawal said. “We offered a UV-LED water disinfection product five years before anyone else. To have a large enough customer base, however, I think you need to be global. That has been our experience.”

iStock / Neyro2008 / WildPixel
iStock / Neyro2008 / WildPixel
A need for standards

The International Ultraviolet Association, Chevy Chase, Md., created a UV-LED task force. Lawal is the association’s immediate past president.

“I initiated the task force two years ago,” Lawal said. “UV-LED lighting lacks standards in testing, manufacturing and systems integration. If I ask 10 different manufacturers for their product properties (e.g., wavelength, life cycle), nothing is consistent. All talk a different language. And it is not just the LED device but the systems around it. The task force’s objective is to give a consistency to how UV-LEDs are characterized. This is a work in progress. The timing is right.”

North American energy codes do not yet address UV disinfection, but Underwriters Laboratories does certify some UV-C products for safety. The New York-based Illuminating Engineering Society’s Photobiology Committee developed ANSI/IES RP-27 addressing photobiological damage from lamps and lamp systems (ANSI/IES 2015). Similar guidance has been issued by the International Electrotechnical Commission, Geneva, and the International Commission on Illumination, Vienna.

While the safety of UV-LEDs is still being explored, UV wavelengths are what they are, no matter the light source. Possible shielding, lower intensity and sensors are all tactics being investigated.

“What I do know is, we work with high- power density UV-LEDs in a smaller footprint, as we do for a water source, or embedded in a device. Because of our approach, UV-LEDs do not raise a safety question,” Lawal said.

Non-UV makes gains

Non-UV antimicrobial LED lighting continues to grow. Manufacturers that have been in the space for a few years are enjoying steady success. In 2019, I spoke with Vital Vio, Troy, N.Y. The company is now Vyv Inc. and has expanded its markets.

“We’ve enjoyed consistent growth in the last year,” said Colleen Costello, Vyv’s CEO and co-founder. “The residential market has been a surprising area. Our partners have helped make this market accessible for us with products that include under-counter kitchen lighting and new ways to introduce this light into bathrooms.”

Costello pointed to the Broan SurfaceShield Exhaust Fan featuring Vyv antibacterial violet light that eliminates bathroom odor.

While healthcare facilities, gyms and schools are natural market’s for continuous disinfecting LED lighting, Vyv lighting is showing up in unexpected places, including the interiors of school buses, behind high-touch elevator buttons and in the lavatories of Delta Airlines’ 757 planes.

“In a world where germs are front and center, it seems we haven’t seen an industry that hasn’t come our way,” said Randy Drawas, Vyv’s chief marketing officer. “Time and money are always investment considerations. Preventive investment is even harder to commit [to], but this resistance is softening as companies see a need to now get ahead of germ problems. We talk to design teams every week and discuss different applications of our technology.”

The effectiveness of non-UV disinfectant light and its light intensity is a knock sometimes leveled by advocates of UV disinfection. Drawas had an answer.

“UV-C is one approach that is very aggressive and can kill germs, mold and viruses in as little as 30 minutes,” Drawas said. “So, the room is clean until microbes reenter it. If your light source is continuous, the disinfection is continuous, so microbes cannot reproduce and are eliminated. You have a clean space with disinfecting light that is safe.

“The higher the ceiling height, the longer it will take for the kill effect. It is a question of lux levels. But the kill will happen, even in shadow areas. It just takes longer. The disinfection rate of our light when operating in the pure violet mode (Vyv Enhanced Antimicrobial) is slightly faster compared to our white light (Antimicrobial+Light).”

In operation, Vyv’s antimicrobial light initially disables a targeted microbe’s reproduction and over a longer exposure kills the microbe.

Finally, it is important to remember using light to disinfect is not a singular remediation.

“The use of light as a disinfection technology typically augments other measures to combat pathogens in the air and on surfaces,” Brons said. “It is rarely, if ever, used as a standalone measure. It should not replace such efforts as increased air circulation or improved air filtration, or the use of chemical agents to kill or deactivate pathogens on surfaces.”

Disinfection light is a tool that is here to stay as germs have become a collective concern. With more research, efficacy and forms, sanitizing light is poised for an exponential rise.

About the Author

Jeff Gavin

Freelance Writer

Jeff Gavin, Gavo Communications, is a LEED Green Associate providing marketing services for the energy, construction, and urban planning industries. He can be reached at gavo7@comcast.net.

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