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Location: Home / Technology / Confusion about disinfection light can be dangerous for people and detrimental to the SSL industry (MAGAZINE)

Confusion about disinfection light can be dangerous for people and detrimental to the SSL industry (MAGAZINE)

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The COVID pandemic has caused great suffering and loss but produced at least one bright spot — the accelerated development and delivery of groundbreaking products and technologies that made it possible to fight COVID-19 more successfully and to better protect people and spaces from additional threats now and in the future.

From a science and technology standpoint, it’s been breathtaking. Breakthrough vaccines were developed in record time. Therapeutics were rapidly tested and added to our arsenal of life-saving treatments. Technology manufacturers created and distributed sophisticated devices to protect our environments, such as advanced ventilation systems, ultraviolet (UV)-powered air purification systems, and disinfecting light tools.

The power to improve lives is the reason that, as a biomedical engineering student many years ago, I began working with antimicrobial light technology. I started out studying the impact of visible antimicrobial light on various bacteria that cause hospital-acquired infections, one of the top causes of preventable death in hospitals (Fig. 1). This study led me to a career as an early developer in antimicrobial LED technology — using visible light to kill and stop the replication of bacteria, viruses, and other microbes.

Unfortunately, we have also witnessed that COVID subsequently triggered a flood of products from questionable sources, and/or with confusing, misleading, or false claims, putting people and companies at risk. Innovative technologies and the industries associated with them must undergo appropriate scrutiny and standards to ensure society can effectively tap into their vast potential.

Misleading product messaging

There are numerous examples of products whose websites and packages include claims that are incomplete, misleading, false, do not sync with science, and do not comply with federal regulations. This is a setup for confusion for the end user that should be cause for increased concern.

For instance, in a home improvement store I saw a handheld UV wand prominently displayed at the cash register, clearly designed for consumers’ home use. The front of the product box claimed the product “kills viruses in seconds” and was “safe & healthy” with no cautionary statements. Yet caution is definitely advised when using UV light.

In a 2020 investigation into UV light safety by an NBC affiliate in Madison WI, Mikhail Kats and Jenn Choy, associate professors who study UV light in the electrical engineering department of the University of Wisconsin – Madison, tested two light wands for safety1. Kats said he “wouldn’t feel comfortable recommending UV wands unless they were being used with a drape over it or with protective goggles.” He also said that it’s unlikely the average consumer will use these safety methods every time, so UV wands may not be worth the risk.

Claims on some UV-C light manufacturers’ websites conflict with the position of experts. For example, one site’s product description of a light fixture reads, “It is always safe for room occupants.” Another states that “there is no adverse human or animal safety risk from far UV-C light.” These statements sound pretty definitive. However, the International Ultraviolet Association (IUVA) stated in a paper on far UV-C that “Claims of skin and eye safety are supported by early findings in mouse tissues, live mouse models, and 3D human tissue models” yet, to date, “these studies have not extended to the exposure of human individuals and so conclusive evidence on acute and chronic exposure are lacking.2” This document — which was reviewed by a diverse set of experts to best represent general consensus — would lead one to believe that those product claims are hardly absolute.

In addition, Environmental Protection Agency (EPA) regulations prohibit the use of the word “safe” in connection with antimicrobial chemicals and devices3. This seems to be overlooked by many manufacturers.

Another example includes machines that emit UV-C light as people walk through a door. In one case, the materials claimed, “Studies* indicate no harm to humans from continuous low dosages of 222 nanometer, far-UVC light”. In this case, there was no footnote to accompany the asterisk that would tell us to which studies the organization was referring. And many experts would disagree that a lack of harm with 222-nm UV radiation has been fully demonstrated. In a paper about UV light safety, environmental engineering professor Karl Linden from the University of Colorado expressed that “the promise of safety has led to some premature and potentially risky uses.”

He wrote, “Some businesses are installing UV portals that irradiate people as they walk through. While this device may not cause much harm or skin damage in the few seconds walking through the portal, the low dose delivered and potential to disinfect clothing would also likely not be effective for stemming any virus transmission. Most importantly, eye safety and long-term exposure have not been well studied, and these types of devices need to be regulated and validated for effectiveness before being used in public settings.4

The Amazon listing for a “disinfection light germicidal lamp” that uses UV-C light claimed, “It can be operated remotely...and you do not need to worry about being injured by ultraviolet radiation during operation,” suggesting that if you turn it on with a remote from another room, you will be safe. But in direct contradiction to this statement, photos accompanying these statements show a person turning on the device with the remote while they are themselves just inches from the UV lamp. This is just one of hundreds of examples readily available to consumers and even marketed to professionals.

The contradictory words and visuals, overstated claims, omissions, and language that is not compliant with regulatory guidance found on so many products and product websites can create confusion and lead any reasonable person to the wrong conclusion about the safety or appropriate use of these devices.

It’s time to clean up claims

While for some making overstatements or omitting critical facts or warnings may sell more products in the short term, it will undermine trust in the long run and, worse, put people at risk. To drive adoption and deployment for healthier environments, disinfection product providers across the supply chain have to find the best way to clearly communicate the benefits and uses of these products.

Know the limits. When the safety of a product depends upon staying under threshold limits — meaning there are slated limits to the amount of radiation to which someone can be exposed per standards set by the International Electrotechnical Commission (IEC) or American Conference of Governmental Industrial Hygienists (ACGIH) — that data should be clearly stated along with the claim of safety. Some products give the impression that they are safe under any circumstances, when in fact there are exposure limits.

For example, for far UV-C to be effective at shorter time intervals, the emission of products using such wavelengths may have to operate near the allowed exposure limits. Many settings where such devices are used clearly have the potential for people to unknowingly exceed those thresholds (think offices, hospital nurse’s stations, public spaces). Another common scenario compounds this risk: If there are multiple devices deployed in a space, it’s even easier to be exposed beyond the stated limits, and several user guide examples don’t mention that. If a product has the potential to no longer be “safe” after a certain period of exposure time, that detail should be presented clearly. In many cases, there are real tradeoffs between speed to inactivate organisms and how close the exposures for people in the space come to the threshold limits. Unfortunately, there are scenarios in which the limits can be exceeded by some products currently on the market for continuous use if they are also killing organisms at the speeds cited.

Buyer (or operator) beware. The safety of UV lights relies on the user’s understanding of the associated caveats and cautions; therefore, all of those cautions must be clearly stated.

In a 2020 position paper about UV-C light, Underwriters Laboratory (UL) along with the National Electronic Manufacturers Association (NEMA) and the American Lighting Association (ALA) stated, “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 if the UVC germicidal device also were to generate ozone5.” (LEDs Magazine has reported on this paper.)

For high-intensity sources, over-exposure can occur in just seconds, but symptoms may not become apparent for a day or two. It’s clear there are risks, but some manufacturer’s statements and claims can be interpreted to suggest the products are safe and free of risks, without condition.

All products are not suitable for all scenarios. Some products should not be marketed for home use at all. Even if there is a warning label or cautions are noted deep in a user guide, that is not enough. The joint paper mentioned goes on to say, “Warning labels are not enough! Children or pets cannot be expected to follow written warnings, and home environments pose innumerable situations that could result in misuse and potential harm when the technical safeguards are inadequate. 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 UVC products. Consequently, we recommend against purchase of products without full safety certification...Even if the device works within safe ranges of operation, and warnings are followed by the person operating the unit, incidents of other members of the household (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.”

The dangers of complex controls in uncontrolled environments

Employing a powerful but potentially dangerous technology in an environment that cannot be controlled will lead to unnecessary risk. As noted earlier, for situations like home use when pets or children may be present, there may be good reason not to use certain technologies at all.

UV light is a very fast and effective killer of germs and is highly efficient in many settings. But since UV light is harmful to humans, it’s important to use it in the right applications where controls can be ensured. Far UV-C may have more flexibility but cautions and limits still apply, and long-term safety has not yet been determined, as previously noted.

Confusion about disinfection light can be dangerous for people and detrimental to the SSL industry (MAGAZINE)

UV or UV-C disinfection, more specifically, may not be the answer in every commercial setting either, as noted in an article published by Hospitality Tech. “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,” wrote contributing organization UL. “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 light6.”

UV technology requires appropriate controls to ensure there is no human exposure, or in the case of far UV-C light, to ensure there is no overexposure. Appropriate UV light solutions implement complex controls, multiple layers of fail-safes, and redundancies to ensure safety and avoid accidental exposure. These complex controls put a lot of responsibility on either those installing the lights, or those ensuring their safe use — a responsibility they may neither be prepared for nor want.

Although rare, the fail-safes can realistically fail. In some environments, there should be zero tolerance for such risk. A major case is the UV light malfunction in Georgia’s Cobb County schools that resulted in UV lights turning on when children were in the building7. The lights were subsequently taken out.

A layered approach with LEDs

Powerful UV light is used in environments such as hospitals or manufacturing facilities only when people are not present. UV can play a powerful role in reducing bioburden in those environments with its ability to quickly kill germs. However, because UV is used intermittently, the results diminish when people reenter the space and microbes are reintroduced to begin their spread and replication once again.

Cleaning with UV light machines or with chemicals is periodic, sometimes taking place once a day or less frequently. This rollercoaster cycle of microbes being tamped down, then increasing again, over and over, is the nature of an environment that receives only intermittent cleaning.

To help close the gaps left in between intermittent cleanings, best practices should include multiple layers of protection. An approach that employs a continuous option such as continuous-use, antimicrobial light at 405 nm reduces surface contamination over time while creating an environment that is both inhospitable to microbes and hospitable for people.

In Fig. 2, the two charts show the difference in bacterial surface contamination levels when solely using periodic cleaning (left) in contrast to applying multi-layered cleaning (right) that adds a continuous cleaning layer using visible antimicrobial light.

Since the 405-nm lights referenced in the figure meet international standard IEC 62471 for continuous and unrestricted use, they are meant to be used where people are working, living, playing, and gathering — all the while inhibiting surface contaminants continuously — with no need for safety controls.

UV light can be advantageous in environments that demand the quickest and most powerful technology and can be controlled to avoid risk. But in many settings where there is high traffic and less downtime for cleaning, an optimal scenario could be to use UV and antimicrobial LED technologies together (Fig. 3). In active settings like schools or hospitals, combining the use of UV-emitting machines operated under the supervision of an expert (when humans are not present) with the continuous action of antimicrobial LEDs can offer a powerful preventive approach to protecting these spaces.


It's incumbent upon everyone involved in the UV and antimicrobial lighting design and distribution chain to employ best practices when it comes to safety and efficacy, and to institute transparency when communicating to customers and end users. Trust and transparency should be our north star as we work to develop products and technologies that continue to light the world and make it a healthier, safer, and cleaner place.


1. T. Hall, “NBC15 Investigates UV Lights; Are they safe and effective?” (Nov. 16, 2020).

2. R.M. Simons, E.R. Blatchley III, and K.G. Linden, “Far UV-C in the 200 – 225 nm range, and its potential for disinfection applications,” IUVA resources (July 2020).

3. Code of Federal Regulations, Title 40, Ch. 1, Subch. E, Part 156, “Labeling Requirements for Pesticides and Devices” (updated Dec. 10, 2021).

4. K.G. Linden, “Ultraviolet light can make indoor spaces safer during the pandemic – if it’s used the right way,” The Conversation (Sept. 9, 2020).

5. UL, NEMA, and ALA position paper, “Ultraviolet-C (UVC) germicidal devices: what consumers need to know” (July 2020).

6. UL, “Why hotels & restaurants should be cautious with using UVC sanitizing tech,” Hospitality Tech (Aug. 21, 2020).

7. WSBTV.com news staff, “Cobb schools already gave UV light company $750K+ before cutting ties, investigation finds” (Mar. 4, 2021).

Legal implications of antimicrobial light claims and compliance

Antimicrobial light devices must meet accepted standards of photobiological safety and efficacy. In the US, antimicrobial lights are categorized as pesticide devices and regulated by the EPA. Because the broader antimicrobial category was originally intended to primarily regulate chemicals, the standards and protocols were based on this. These protocols have been evolving to reflect the addition of newer technologies like light. While there is no standardized protocol yet to quantitatively test light devices, manufacturers and labs follow the existing protocols and modify them to enable testing of wavelengths of light. No doubt, standardized protocols for light products will not be far away.

The EPA does not require review of the testing of pesticide devices by its organization when it comes to safety or efficacy in order for a product to be on the market. Officials rely on manufacturers to test their products according to protocols and standards developed by AOAC International or ASTM International. In Canada and the European Union, products may test to standards set by IEC. Independent, certified testing labs such as UL, Intertek, TÜV SÜD, and others offer services to test products against these standards to verify compliance.

While the EPA does not verify safety and efficacy testing for pesticide devices, it does provide guidance and enforcement on efficacy data and claims to ensure that manufacturers do not use false or misleading claims about safety or efficacy.

First, it’s the responsibility of the manufacturers to have credible scientific data to support the claims they make, to only make claims they can support, and to properly qualify all claims. In the EPA’s Compliance Advisory, the agency states that all claims in connection with the sale or distribution of devices must be true and not misleading — this includes claims made in marketing materials and on websites. It’s clear that there is work to do here. Many manufacturers do not have even basic EPA registrations in place, which is a violation. Both current compliance and enforcement leave a lot to be desired.

Beyond the human and reputational risks the lighting industry might face, there is a growing legal liability risk. After the flood of questionable COVID-triggered products hit the market, a slew of COVID-era lawsuits was not far behind. These lawsuits have been filed against a variety of companies that distribute products such as masks, hand sanitizers, cleaning solutions, UV products, and more, and have focused largely on unsubstantiated or misleading marketing claims.

These lawsuits demonstrate not just the very real human risk but also the risk of liability that can bring financial penalty and business disruption. Additionally, they raise the potentially longer-reaching issue of threats to manufacturers’ reputations. ♦

Get to know our expert

COLLEEN COSTELLO is a biomedical engineer and former researcher at Covidien Surgical, Mount Sinai School of Medicine and Weill Cornell Medical College. She is CEO and co-founder of Vyv, a creator of proprietary antimicrobial light technology used in aviation, transit, maritime, commercial food services and processing, healthcare, commercial spaces and integrated into consumer products from exhaust fans to humidifiers. Costello has been a speaker at various industry events. She has a bachelor’s of science in biomedical engineering from Rensselaer Polytechnic Institute.

*Vyv offers antimicrobial lighting products that utilize 405-nm technology.