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lightingBy Cliff Yahnke, PhD

The pandemic focused the public’s attention on infectious disease and how it is spreads. While this has always been a consideration in acute healthcare, it has become increasingly critical in non-healthcare applications, such as offices.

More employees are being asked to return to work—office occupancy across 10 major US cities crossed 50.4% of pre-pandemic levels for the first time since early 2020, according to security swipe tracker Kastle Systems—although things are not the same as they once were; much has changed as COVID-19 has brought about a new normal. As effective as vaccines and boosters are against COVID-19 and current variants, employers planning to reopen offices have a lot to consider, such as what infection control measures will employees accept as sufficient?

Workplace Design

Workplace design not only directly impacts employees’ experiences, but their health and safety, too. The AEC industry, facility managers, developers, and building owners need to collaborate to incorporate infection control practices into workplace interiors. These may include a variety of safety and design measures, as well as adopting practices that are common in healthcare facilities. It’s imperative to address risks of pathogen transmission and create restorative environments where building occupants feel safe, comfortable, and supported.

Whole-Room Disinfection

During a panel discussion, Dr. Adam Seidner, chief medical officer at The Hartford said, “Infectious diseases are out there—they always have been out there and they’re here to stay…We need to embrace universal source controls to keep COVID outside. Cleaning, sanitation, and the hybrid work model is here to stay.”

For years, whole-room disinfection systems have been utilized in healthcare to mitigate the transmission risk of infectious disease. With the coronavirus pandemic, many people managing nonhealthcare environments are considering deploying these systems as well.

Conventional disinfection methods are limited by reliance on the operator to ensure appropriate selection, formulation, distribution, and contact time of the agent. Automated room disinfection systems remove or reduce reliance on operators and so they have the potential to improve the efficacy of terminal disinfection. One such system is 405nm lighting technology, which ​is clinically proven to effectively inactivate SARS-CoV-2 Influenza-A H1N1 without the use of photosensitizers and is installed at over 600 healthcare facilities throughout the U.S..

405nm Technology

Scientists and engineers have developed technology that utilizes 405 nanometer indigo visible light (non-UV) to provide safe disinfection around the clock, even when people are present. These luminaires automatically kill viruses, bacteria, molds, yeast, and fungi in the air and on surfaces, without the need for specially trained staff. Unlike ultraviolet lighting (UV), 405nm visible light is both direct and indirect. Reflecting off walls and other surfaces, it kills pathogens in shadowed areas UV lighting can’t reach, maintaining bioburden reduction between terminal cleanings

Rather than relying solely on staff to clean surfaces, or HVAC systems to purify the air, the patented technology combines the benefits of both. Using the visible light spectrum, the technology is safe at all times, even when performing at its highest level of disinfection. Which means no room downtime, and no worries about safety.

There are numerous reasons this technology is recommended over UV lighting, the most important is safety—a key issue with employees feeling comfortable returning to the office.  The public is generally aware of the potential hazard from UV light but often confuses visible light for being UV as well. While visible light can be integrated in a way that makes it appear as typical, white LED light, UV-A light cannot. Researchers have demonstrated that UV light can damage materials, including fabrics and plastics. A recently published study showed the effect of UV-A light upon irradiated blue fabric swatches in a neonatal intensive care unit. Many inks today are cured using UV light and can fade over time if exposed to UV light of the corresponding wavelength. To date, this effect has not been documented with visible light.

Ultraviolet Light

UV disinfection is one type of no-touch technology shown to be a successful adjunct to manual cleaning in reducing environmental bioburden. This technology is designed for use in operating rooms, patient rooms, and other healthcare settings. Some manufacturers are developing luminaires that incorporate UV-A, B or C technology; however, the FDA has asserted that UV in all forms presents a human health hazard.

Essentially, UV light kills bacteria and viruses by damaging their nucleic acid, thus destroying their ability to replicate and cause disease. UV wavelengths, which are less than 400nm, are beyond the range of visible light, and can kill pathogenic microorganisms. Most experts agree that the C bandwidth (~100nm-280nm) is the most germicidal, and that UV-C light can remove approximately 99 percent of microbial contamination in the air and on surfaces. The energy required to kill microorganisms is a product of the UV light’s intensity and exposure time, measured in micro-watt seconds per square centimeter.

Short wavelengths can kill pathogens through a variety of pathways, depending on the wavelength, duration and amount of optical radiation. The advantage of UV-C technologies for minimizing HAIs is an effective dosage can be achieved with short time durations of less than one hour. Unfortunately, there are many disadvantages to this technology.


The disadvantage of UV-C is that the radiation must be applied when the room is unoccupied as it is inherently harmful to humans. Additionally, as a tool for disinfection, UV has other numerous drawbacks:

  • Upper air disinfection creates unsafe zones within the room that users may not be aware of
  • Portable devices require specialized staff and training to operate
  • Episodic—once UV disinfects the room and is removed, pathogens immediately begin to re-enter the space: in the air, on staff, and on surfaces
  • UV requires line of sight to work—if a surface is in shadow, it will not be disinfected
  • UV sources degrade, requiring replacement in as little as four months and at considerable cost when operated continuously
  • UV causes material degradation, damaging plastics and fading fabrics/finishes

Exploring New Solutions

Returning to the “workplace as usual” is a thing of the past. Employers, building owners, and facility mangers are exploring innovative ways to ensure facilities are safe and minimize disease transmission. Exploring and implementing new technologies that help deliver infection-resilient environments supports public health during and beyond the current COVID-19 pandemic. As we look forward, it is critical to understand that the workplace design not only directly impacts employees’ experiences, but their health and safety, too. This will require designers, facility managers and business owners to work together to incorporate safe and effective infection control practices.


  • J.A. Otter, S. Yezli, F. Barbut and T.M. Perl, “An overview of automated room disinfection systems: When to use them and how to choose them,” National Library of Medicine, November 29, 2019.
  • J.A. Brons et al., “An assessment of a hybrid lighting system that employs ultraviolet-A for mitigating healthcare-associated infections in a newborn intensive care unit,” Lighting Res Technol, 0:1–18 (2020).
  • D. Irving et al., “A comparison study of the degradative effects and safety implications of UVC and 405nm germicidal light sources for endoscope storage,” Poly Deg Stab, 133:239–254 (2018).
  • JA Brons, A. Bierman, R White, K Benner, L Deng, MS Rea, “An assessment of a hybrid lighting system that employs untraviolet-A for mitigating healthcare associated infections in a newborn intensive care unit,” The Society of Light and Lighting, January 2020.

Yahnke is the Chief Scientist and Head of Clinical Affairs for Indigo-Clean and Kenall Manufacturing. Indigo-Clean is a registered trademark of Kenall Manufacturing Co., a Legrand company. The company creates unique solutions for the healthcare, cleanroom/containment, food processing, transportation, high abuse, and correctional lighting markets.

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Facility Executive Magazine