Industries that have been decimated by the pandemic are seeking out any reasonable measure that might prove effective in fighting the virus. UVC radiation — the most energetic in the UV spectrum measured between 180nm to 280 nm — is proven to have sanitizing and germicidal effects and first evidence of its effectiveness against SARS-CoV-2 is emerging2. Hospitality companies are aware of this and seem to be interested in deploying this technology quickly within hotels and restaurants. A quick online search shows that some hospitality companies are incorporating UVC devices on-property in several ways to disinfect guestrooms and common touch points such as doorknobs, computer keyboards, and TV remotes.
But, there is reason for hotels and restaurants to be cautious: any uncontained UVC exposure that is strong enough to kill germs is a risk to people, pets and plants. This is true with any high-energy UVC device.
To address these issues, UL published a position paper titled: Ultraviolet-C (UVC) germicidal devices: what consumers need to know3. The publication has two stated goals: to bring attention to ultraviolet light device safety risks; and to help manufacturers, retailers and consumers understand what makes devices safe by design and under what controlled conditions they can be operated safely.
Examining the different types of UV
UVA, UVB and UVC, are all part of the spectrum of energy emitted from the sun. The longer rays (280nm to 400 nm UVA and UVB) reach Earth’s surface and are essential for all life and for humans to produce vitamin D and other essential body processes. UVA and UVB also cause tanning, sunburn, skin cancer and wrinkles depending on skin type. Less well known is the UVC band of the sun’s radiation, which is shorter in wavelength (180 nm to 280 nm) and does not penetrate Earth’s atmosphere. UVC has been proven to have the most germicidal benefits. Perhaps the shorter wavelength absorption by the atmosphere is one of the reasons it is so effective at deactivating viruses, as viruses have not had to evolve to survive under UVC.
UVC over-exposure can cause damage to the eyes and skin, based on wavelength, intensity, proximity to the source, and time of exposure. In certain cases, there are also risks to the lungs when the UVC germicidal device uses the type of lamp that generates ozone. For high intensity sources, over-exposure can occur in just seconds, but symptoms may not become apparent for a day or two. UVC lamps have little visible light output, so our natural defensive reactions to optical hazards (blinking, squinting, or trying to look away) may not be triggered to protect us adequately.
Exploring the possibilities while mitigating risks
With the commitment to the safety of workers in the hospitality industry, the question that should be foremost in our minds is: “How do we reap the rewards while mitigating the risks?”
Unfortunately, the online retail market is growing rapidly with handheld and portable UVC germicidal devices, many of which do not employ proper containment of the radiation to protect people or other equivalent means of protection. Instead, these tend to rely solely on markings or integral timers, unreliable sensors, or remote controllers, which still leave room for scenarios where humans or animals can be over-exposed to the UVC light. Without better safeguards, without full awareness of the risks of purchasing safety-certified devices and without facility workers trained in proper operation, this would place an unrealistic responsibility on the user and, consequently, such products at present cannot be certified. For all UVC products sold, certification is essential.
Proceed with caution and start with what’s worked
UL does not believe it is reasonable (in a non-controlled setting) to rely on behavioral safeguards alone to mitigate risks of personal injury from UVC products. Consequently, we recommend against purchase of products without full safety certification. Most hospitality environments cannot be assumed to be a controlled environment for correct use of these products. Even if the device works within safe ranges of operation, and warnings are followed by the person operating the unit, incidents of hospitality guests (such as children, pets and certain elderly) entering an area where the device is on, should be accounted for in the safety measures of the device.
In other words, the safety of hospitality workers and their guests cannot be guaranteed by simply buying a device on the internet and following the manufacturer’s directions.
For UVC germicidal devices intended for use in industrial, commercial or healthcare settings, where there is a clear understanding of the risks and necessary precautions to keep building occupants safe, a path exists that will allow those products to be certified by an Occupational Safety and Health Administration (OSHA) Nationally Recognized Testing Laboratory.
One approach that deserves special attention is upper air UV germicidal irradiation (UVGI). As we learn more about this pandemic and its spread from person to person through breathing,
UVGIs can be an effective tool in preventing infections by exposing the air in the space to UVC when operating at sufficient air exchange rates.
The following excerpt is from a Public Health Report: The History of Ultraviolet Germicidal Irradiation for Air Disinfection4:
Upper-room UVGI is one of two primary applications of UVGI air disinfection. Designed for use in occupied rooms without using protective clothing, upper-room UVGI uses wall-mounted and ceiling-suspended, louvered/shielded UVGI fixtures to confine the germicidal radiation to the entire room area above people's heads and greatly minimizes exposure to occupants in the lower room. Effective air disinfection in the breathing zone then depends on good vertical air movement between the upper and lower room, which can be generated naturally by convection, the HVAC system, or low-velocity paddle fans where needed.
Lastly, the concept of “dosage” must be taken into consideration. While it is a common term in the field of medicine, it is not a common term in the hospitality industry. UVC over-exposure can cause damage to the eyes and skin, based on wavelength, intensity, proximity to the source, and time of exposure. In the example of deploying UVGI, after installation the commissioning engineer will take radiation measures to ensure that UVC reflections (from the walls or ceiling) don’t expose people.
Due to the complexities of delivering effective solutions and the risks of missing a critical safety detail that may create health risks, property owners should rely on professionals who are knowledgeable about the approaches and technologies being considered. These professionals are also aware of the required training and safety certifications for workers participating in the delivery of UVC.
It's possible that when we look back at this time, we’ll come to understand that it was a myriad of sound practices, from social distancing, wearing masks, the development of vaccines, and the use of technologies such as UVGI that largely enabled us to overcome this once-in-a-century pandemic.
1 Far-UVC light (222 nm) efficiently and safely inactivates. airborne human coronaviruses. Buonanno, M., Welch, D., Shuryak, I. et al. Sci Rep 10, 10285 (2020). https://doi.org/10.1038/s41598-020-67211-2
2 Lighting Firm Signify Says UV Light Breaks Down Coronavirus Particles in Seconds; Boston University National Emerging Infectious Disease Laboratories. June 12, 2020. https://www.bu.edu/neidl/2020/06/6004/
3 Ultraviolet-C (UVC) Germicidal Devices: What Consumers Need to Know. UL, Inc. August, 2020. https://www.ul.com/offerings/ultraviolet-uvc-light-testing-and-certification
4 The History of Ultraviolet Germicidal Irradiation for Air Disinfection. Nicolas G. Reed. Public Health Report, 2010 Jan-Feb. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2789813/
Note: In this article, ‘certification’ only addresses device safety and does not make any statements regarding product effectiveness in sanitization and germicidal capabilities, or other manufacturer claims.
About UL: UL shares our technical expertise as a third-party certifier by participating in the development of national and international safety standards. We have helped develop more than 1,600 standards to define safety, security, quality and sustainability.
Please visit UL.com/uvlighting for a more detailed chart of UVC products for consumer, commercial, healthcare and UVC germicidal device components and information about their path to certification.