Shining a light on UV disinfection
By Andrew Snook
Are UV devices safe and effective against COVID?
By Andrew Snook
If you are thinking of purchasing ultraviolet lighting equipment as a means of protecting yourself and your staff against COVID-19, then you better make sure to enlighten yourself about the various types of UV lighting and their applications, the training required to operate the equipment, and, most importantly, according to experts, which pieces of equipment can back their claims with the proper certifications.
So, how do you start when looking into purchasing UV equipment for disinfection applications? Well, let’s start with the types of UV.
Types of UVs
There are three types of UV radiation: UV-A, UV-B and UV-C. These radiation types are classified according to their wavelengths (the shorter the wavelength, the more harmful the UV radiation). Here are their definitions as provided by the World Health Organization.
Ultraviolet-A: The relatively long-wavelength UV-A accounts for approximately 95 per cent of the UV radiation reaching the Earth’s surface. It can penetrate into the deeper layers of the skin and is responsible for the immediate tanning effect. Furthermore, it also contributes to skin aging and wrinkling. For a long time, it was thought that UV-A could not cause any lasting damage. Recent studies strongly suggest that it may also enhance the development of skin cancers.
Ultraviolet-B: Medium-wavelength UV-B is very biologically active but cannot penetrate beyond the superficial skin layers. It is responsible for delayed tanning and burning; in addition to these short-term effects it enhances skin aging and significantly promotes the development of skin cancer. Most solar UV-B is filtered by the atmosphere.
Ultraviolet-C: Short-wavelength UV-C is the most damaging type of UV radiation. However, it is completely filtered by the atmosphere and does not reach the earth’s surface.
Of the three types of UV radiation, UV-C has been used for antimicrobial purposes since the 1930s. It remains today the only one broadly accepted for germicidal devices due to its proven sanitizing and germicidal effects in the healthcare sector. The pandemic has stimulated the introduction of a number of new UV disinfecting devices, some of which operate in the UV-A wavelengths of 315 to 400 nanometers. While UV-A has the advantage of generating less heat and being much safer for use around people, it’s effectiveness as an antimicrobial is not well established. According to Advanced Biotechnologies, a medical supply company, “For UV sterilization, only UV-C (100-280 nm) has high enough energy to effectively kill microorganisms.”
A study in the Journal of Virology, “Predicted Inactivation of Viruses of Relevance to Biodefense by Solar Radiation,” says “The most effective wavelength for inactivation, 260 nm, falls in the UV-C range, so-named to differentiate it from near-UV found in ground-level sunlight, i.e., the UV-B and UV-A portions of the spectrum, 290 to 320 nm and 320 to 380 nm, respectively. Nucleic acids are damaged also by UV-B and UV-A, but with lower efficiency than by UV-C radiation.” UV kills microbes by destroying the DNA in their nuclei – the nucleic acids the Journal refers to. Other studies found some limited efficacy of UV-A on viruses, but only under lab conditions and long exposures. And no UV disinfectant technology has been proven to work on COVID-19 specifically.
Bahram Barzideh, primary designated engineer in UL’s lighting division, chimes in: “We have known for a long time that sunshine works as a disinfectant. There are studies that show how a high percentage of bacteria can be killed in approximately an hour on a bright sunny day. Sunshine is comprised of UV-A and UV-B. UV-C is blocked by the Earth’s atmosphere. UV-C is the most energetic in the UV region and can deliver high exposure dose, based on the UV source intensity, UV source proximity to the target area and UV source exposure time. For this reason, UV-C is most effective in disinfection applications. We know that UV-C is very effective for killing bacteria and inactivating viruses, so the presumption is that it is also effective on COVID-19. I am aware of manufacturers working on continuous operation UV-A systems. In these systems the lower UV source intensity (energy) is compensated with longer exposure doses.”
The emerging market of consumer UV-C germicidal devices also has some lighting industry and healthcare professionals concerned.
“There’s general concern out there,” says Sean McCrady, national service line manager for IEQ at UL. “There’s a lot of marketing going on right now when it comes to the ‘miracle solution’ for COVID-19. More than ever, people are throwing caution to the wind in a state of panic. It makes sense to take a step back, take a breath, and look at what the application is being used for. Is the person using it properly trained? What are they trying to do? Is it something that can be done potentially as effectively with soap and water or a typical cleaning practice? Are you using it as a technology to clean equipment in a janitorial effort or trying to clean the air as well?”
Touchpoints are no longer considered the main cause for the spread of viral transmissions like COVID-19. While people should still practice proper disinfection procedures for equipment to help prevent the spread of the virus, McCrady says there should also be a focus on the areas that offer greater risk of spread, like indoor air quality.
Adam Lilien, global business development of connected technologies at UL, says that use of UV-C for ultraviolet upper air germicidal irradiation (known as UVGI) has the potential to be effective to help prevent the spread of COVID-19 in an indoor space, where people are socially distancing themselves but still sharing the same air. He says the technology has been thoroughly researched and has been around since 1930 to disinfect the air above the people coming into an indoor space.
“It’s the combination of handling the air and using the proper devices that one can irradiate the space above people – especially if it’s an effective technology, and it’s designed properly, and it’s installed properly, and it’s commissioned properly,” Lilien says. “Then the air droplets that are aerosolized from person-to-person spread, under the proper conditions, can be greatly reduced.”
In a recent paper titled, “Ultraviolet-C germicidal devices: what consumers need to know”, many of the concerns surrounding consumer devices are highlighted in detail. The paper was produced as a collaboration between UL, the American Lighting Association and the National Electrical Manufacturers Association.
One of the major concerns highlighted in the paper was the need for proper containment of UV-C sources to ensure users do not become over-exposed to UV-C radiation:
Unfortunately, the online retail market is growing rapidly with handheld and portable consumer oriented UV-C germicidal devices, many of which do not employ proper containment 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 UV-C light. Without better safeguards and without consumers being more fully aware of risks and trained in proper operation, this would place an unrealistic responsibility on the user and, consequently, such products at present cannot be certified. For all UV-C consumer products sold, certification is essential.
The organizations noted in this document do not believe it is reasonable (in a consumer setting) to rely on behavioral safeguards alone to mitigate risks of personal injury from UV-C products. Consequently, we recommend against purchase of products without full safety certification.
The proper installation of certified UVGI devices is also essential to help prevent over-exposure of UV-C radiation. One simple way to help ensure safe installation is to hire a professional.
“Do not try and do this without them,” Lilien warns. “Somebody who is certified, works with the equipment all the time, installs it and commissions it, avoids the risks that we outline in our position paper quite well, that, in the hands of the uncertified, the risks will likely create problems for health of the workers.”
To find a certified professional, he recommends searching out a reputable MEP firm (mechanical, electrical and plumbing).
“Your MEP firm will be very cautious to advise you if they don’t have the right certifications internally. They don’t want to close a sale and risk their licenses,” Lilien explains. “The types of things we’re talking about with human health would clearly be a risk to the firm itself. So, they’re going to be very upfront and honest, as long as it’s a reputable firm. I’d call my MEP firm that already knows my air circulation patterns in my space – if we’re talking about upper air. Even with things like handheld wands, which can be used in medical spaces very effectively, you can imagine the protocols that a hospital has to ensure that the people who are handling radiation devices are properly trained in the protocols.”
Another way UV-C devices are being installed to clean the air is in the form of UV-C in-duct applications.
“Essentially, you put UV lights in the air stream inside a supply air duct for an air conditioning system. Those have some benefit, without a doubt, speaking outside of just dealing with a virus in general,” Mccrady says, adding that they can keep systems very clean and help prevent coils from fouling and keep mould from growing where the light is shining.
With these types of UV-C devices, there are still things that need to be considered prior to the purchase and installation of the equipment, which makes it vital to hire a professional.
“It can also degrade certain materials. You need to make sure you have UV-safe flex joints, for example,” Mccrady says.
He says that air moving in an air duct travels at a very high velocity, and that should be considered when deciding on the purchase of UV devices for the purpose of disinfecting the air.
“Typically, it takes a little bit of time for UV light to be in contact with stuff in the air to really have an impact,” Mccrady says, adding that is what makes upper air UVGI devices potentially effective. “With the upper room, you have much slower air movement. You have air passing several times essentially over that light. There’s much more contact time for there to be a benefit.”
Certified equipment is key
Lilien says proper certification of UV-C devices, highlighted in the collaborative paper between UL, the American Lighting Association and the National Electrical Manufacturers Association, is vital.
For UV-C 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 Nationally Recognized Testing Laboratory.
“The NRTL is critical in determining when it is safe for use. I wouldn’t purchase something without it,” Lilien says.
The National Electrical Manufacturers Association Lighting Systems Division recently endorsed the Global Lighting Association’s position statement on germicidal ultraviolet irradiation.
NEMA stated that UV-C devices are considered safe as long as they meet the applicable safety requirements provided in the International Electrotechnical Commission and/or Underwriters Laboratories Standards or other regional safety requirements.
“The position statement provides current safeguards to avoid human exposure to irradiance hazards and excessive ozone concentrations while NEMA and other Standards developing organizations work on comprehensive technical standards for the safe operation of these devices,” stated NEMA Lighting Systems Division industry director, Karen Willis.
The Global Lighting Association’s position statement on germicidal ultraviolet irradiation is available in its website’s online library.
Health Canada’s recommendations
Canadian Rental Service asked Health Canada what its recommendations are regarding the use of UV-C lighting for disinfection purposes for the general public; precautions consumers should take to ensure they are purchasing safe UV-C lighting equipment; and if there are any guidelines for what is considered a safe amount of exposure to UV-C devices. This was Health Canada’s response, as provided by Eric Morrissette, chief of media relations for the Communication and Public Affairs Branch serving Health Canada and the Public Health Agency of Canada:
“To date, Health Canada has not issued any authorizations for UV-C room disinfecting or sanitizing units as medical devices or as pest control products. General information regarding ultraviolet radiation is available on Health Canada’s website.
Health Canada’s Medical Devices Directorate regulates the sale, advertising for sale and importation for sale of medical devices under the Medical Devices Regulations of the Food and Drugs Act, whereas Health Canada’s Pest Management Regulatory Agency regulates pest control products under the Pest Control Products Regulations of the Pest Control Products Act.
The intended use and claims associated with a particular UV-C room disinfecting or sanitizing unit, may be subject to oversight as a COVID-19 medical device or as a pest control product. Consumers as well as rental stores should verify that the appropriate authorization is in place in advance of purchasing any UV-C room disinfection or sanitizing unit. The list of authorized COVID-19 devices is available on Government of Canada’s website and the list of authorized pest control products is accessible through the Pesticide Product Information Database.”