A new use of light emitting diodes (LED) has emerged. LED light is killing bacteria, fungus and mold, and the scientific community has validated the results. Lab researchers, diode fabricators and fixture manufacturers are working to market LEDs that are an effective and safer disinfectant than ultraviolet (UV) light, while also offering a much longer operational life. This newfound application could be a game-changer.

A pioneer in researching visible light disinfection, the University of Strathclyde in Glasgow, Scotland, reported in 2008 it had discovered a proper blue-light wavelength of high-intensity visible light using LEDs that could deactivate methicillin-resistant Staphylococcus aureus (MRSA) and other strains of bacteria. Intensities of 400 to 420 nanometers (nm) did the trick, 405 being the sweet spot for bacteria deactivation. In 2012, LED work continued with blue light disinfecting other bacteria including listeria and E. coli. Then and now, the university licenses its patented LED technology. Other supportive domestic research over the last five years has included work by the Harvard Medical School in Boston and the Department of Defense Infectious Diseases Service at San Antonio Military Medical in Houston. NASA has done work, as well.

In short, the intensified LED blue light excites certain molecules in harmful micro-organisms through photo-activation. Reactive oxygen species are then produced that damage and kill the harmful cells.

Neu-Tech Energy Solutions, Terrace Park, Ohio, has been fabricating its own sanitizing LED luminaires over the past four years. A smaller lighting business, the firm has some 40,000 traditional LED lights installed in different applications across the country. Florida-based Gary Neumann is the company’s marketing manager.

“When it comes to antimicrobial blue light, hospitals largely use ultraviolet light,” he said. “When using UV for longer periods, such as for room disinfection, you must vacate the space, as UV will harm your eyes. You don’t have that eye problem with LEDs.”

Unlike UV, LEDs do not use electromagnetic radiation to emit light. UV-C is the typical application of ultraviolet for germicidal control and generates more energy than the other types of UV rays.

Neumann added his firm’s sanitizing LED products are being demonstrated for clients. Neu-Tech also is refining its product and discovering new applications. The lights have taken different forms, including linear and can lights for overhead applications, handheld fixtures, and more.

“There are challenges in crafting antimicrobial lighting,” Neumann said. “When replacing fluorescent tubes with linear LED bacteria lights, they still need to operate for general illuminance. So you need both white and blue light. Can you do enough white to provide enough general lighting but enough blue for bacteria control? That’s the challenge. This is where we experiment and discover the right balance. It can be tricky. With linear in particular, you use a diffuser to spread the LED light. Does the diffusion weaken the bacteria-killing ability of the blue light? You need to make sure it doesn’t.”

Neumann said his company’s antibacterial linear lights have proven to kill the MRSA virus. In addition, new applications have emerged, and they dictate different LED forms, including a mold-remediation flood lighting fixture and a portable, 240-degree rotatable LED light for medical applications.

“We’ve had doctors, orthopedists, dermatologists use our lights in handheld applications,” Neumann said. “I have a recessed fixture placed in my shower to kill mold. One of our fixtures can be inserted within air handlers. It has made a big difference killing fungi and other molds present in ducts. We’ve also placed our linear lighting in kennels. It has eliminated what is called ‘kennel cough’ in the dogs. The blue light has calmed the dogs, as well.”

Neumann is enthusiastic about the commercial future for LED antimicrobial lighting.

“I think this kind of lighting will be everywhere,” he said. “There are so many places to use it. Think of health clubs and gyms, college dorms or daycare centers. Think of restaurants as the blue light has proven in testing to kill salmonella. In meatpacking plants, it could kill listeria. Electrical contractors could put these in almost everywhere and introduce this lighting to projects.”

A nascent market

Other companies, such as Kenall, Kenosha, Wis., have jumped into the LED disinfectant market. The company is targeting hospital-acquired infections with its Indigo-Clean. According to 2016 stats, the Centers for Disease Control and Prevention reported, “Each day, approximately one in 31 U.S. patients contracts at least one infection in association with his or her hospital care.”

Using a combination of 405-nm indigo and white LEDs, Indigo-Clean kills bacteria while providing ambient illumination for the space, similar to Neu-Tech.

Meanwhile, Vital Vio Inc., Troy, NY, has its own linear product.

“Our company was R&D focused up through 2016–2017 before we felt confident that we had a commercially effective and viable product,” said David Haar, senior director of strategic marketing for Vital Vio. “I think one of the big reasons that it [antimicrobial LED] is a growing area is that the need is so great. It may prove to be most effective in fighting resistant bacteria. We are running out of tools to fight germs. If they get out ahead of us, what do you do? LED antibacterial light is showing great promise.”

Vital Vio targets markets cited by Neu-tech and Indigo-Clean, in addition to transportation (e.g., airplane cabins), public transit, public bathrooms, offices and hotels.

“There is also an emphasis on reducing chemicals in green cleaning products,” Haar said. “LED technology disinfects without chemicals. Both commercial and consumer markets are attracted to this.”

Haar also feels LED disinfectant technology offers endless market applications.

“A hospital provides any number of spaces for continuous disinfection protection using this special LED lighting,” he said. “You have patient rooms, but you also have high-risk wards for neonatal or cancer patients especially vulnerable to infection.”

Vital Vio recently received its fourth patent for its single diode technology.

“We designed our product so a user could flip a switch to what we call ‘Eco Mode’ using only the violet spectrum for straight disinfection when a space isn’t occupied, perhaps applied overnight,” Haar said. “Our light could also be engineered to switch to its White Light Disinfection mode in, say, a bathroom using occupancy sensors. Conceivably, the light would remain in Eco-Mode until someone enters. We purposely named the color spectrum of our disinfectant light ‘violet’. While it is in the blue spectrum, we don’t want the market to confuse what our product does with luminaires that use blue spectrum light to support circadian rhythm.”

Vital Vio tunes its violet light between 400–450 nm to effectively kill bacteria, fungus and mold. Its luminaires take different forms, including linear, to fit 2-by-2-foot or 2-by-4-foot troffers and other downlight fixtures. The firm also licenses its technology. In 2018, it partnered with Evolution Lighting LLC, which uses Vital Vio lighting in recessed shallow can and undercabinet lighting under the Ellumi name.

Haar explained the biggest obstacle for LED antimicrobial lighting is the proof of concept.

“People want to see others use it first before they spend the money,” he said. “Confirm it’s effective. This technology will go through an early-adopter phase, but I believe the mainstream market will rapidly follow. There will be a critical mass when enough hospitals or food processors adopt it. The embrace of LED light will help, as well. In the end, who wouldn’t want a luminaire that can also disinfect?”

Big lighting takes notice

Disinfectant LED lighting has also grabbed the attention of major lighting manufacturers. Hubbell Lighting Inc., Greenville, S.C., will introduce SpectraClean this year. It features licensed technology from the University of Strathclyde.

“We are preparing to launch five SpectraClean-enabled products for commercial and industrial applications including recessed troffers, commercial strip lights, highbays and linear vaportites,” said Jeff McClow, product manager. “Our focus will be commercial buildings including offices, education and child care. We are also interested in the transportation sector, food preparation and public restrooms.”

McClow said Hubbell heard of a need for antiseptic lighting in the field and had been privy to discussions related to the topic at trade shows, conferences and seminars. One example was Lightfair International where exhibitors had begun to show related lighting products.

“It got people talking, including us,” McClow said. “This could be a strategic market to pursue. Not only is LED visible light disinfection safer than UV, it also avoids harming paint colors and fabrics that can degrade under UV exposure.”

SpectraClean is being designed to operate in four different modes: blended (405 nm enhanced white light and continuous disinfection), blended plus adding a more powerful disinfection cycle of 405 nm light during unoccupied off-hours, independent (white or disinfectant light), and dedicated (disinfectant mode only).

McClow anticipates food manufacturing and healthcare will initially be the most active markets for LED light disinfection.

“It’s conceivable schools might be early adopters, too, since administrators want to protect students, teachers and staff,” he said. “This is also a product that could feed into the healthy building movement. While this is a premium lighting product, I do think customers will understand the two-for-one value proposition of general lighting and disinfection.”

All of the lighting the manufacturers cited is third-party tested. It must also meet national lighting and safety standards applicable to any LED luminaire or fixture.

“Historically, sunlight has been the cure from a number of pathogens,” Neumann said. “LED disinfection is interior light at the right nanometers without the harmful rays.”