Myriad germicidal UV developments change the SSL name game (MAGAZINE)

Oct. 8, 2020
MAURY WRIGHT examines common terminology used when discussing germicidal ultraviolet technology, and notes that a change in descriptors may be required for clarity.

What’s in a name or a label, anyway? Well, in a technology magazine, consistent usage of labels, brands, descriptors, metrics style, if you will contribute positively to readers correctly digesting content. Mostly we get our style usage right, and we occasionally have been wrong. And sometimes the phraseology we have adopted just gets run over by new technology developments such as in germicidal ultraviolet (UV) applications. I’ll explain the changing disinfection landscape relative to SARS-CoV-2 and the impact on our descriptions of it.

While the SARS-CoV-2 coronavirus that causes COVID-19 is fairly new, disinfection using electromagnetic energy is not. We’ve covered deactivation of pathogens going back probably a decade. But COVID-19 has fundamentally changed thought processes, usage models, and yes, phraseology.

We first wrote about using UV-C-band (100–280-nm) LEDs to kill pathogens. We’ve since learned that “kill” isn’t what happens but rather deactivation is the desired outcome (see our Last Word from this issue for more details). The early coverage was more wishful thinking than practical due to the cost and relatively low power output of UV-C LEDs. But there was obvious great market potential, for instance, in instantaneous water disinfection.

Then we learned about the use of violet and later UV-A-band (315–400-nm) energy to deactivate pathogens. The longer-wavelength energy uses a different mechanism to deactivate a pathogen relative to the shorter-wavelength UV-C, and the longer-wavelength energy requires a much longer duration of exposure to work its magic.

I have no way to exactly trace the chronology, but I think it was Kenall that I first experienced using the phrase “continuous disinfection” to describe the operation of its violet technology. The violet energy could be used safely while people were in a space, and the usage model was 24/7 operation to constantly fight pathogens in places like locker rooms or hospital rooms. The word “continuous” was adopted as a differentiator to UV-C offering instantaneous disinfection. And so we at the magazine began to use those phrases to describe the related but different technologies and applications.

Recently, however, GE Current announced a UV-C-based, round puck-like, ceiling-mounted product specifically targeted at SARS-CoV-2. But Current also suggests that its product be used continuously, and even has a new brand 365DisInFx that implies 365-days-per-year usage.

The new Current product is designed to emit low levels of UV-C irradiance so that it can be safely used while people occupy a space. The low dosage means that deactivation doesn’t happen instantaneously, although it may not take as long as the UV-A or violet technology. Current’s initial product will target deactivation of SARS-CoV-2 in three hours. The longer disinfection time isn’t perfect, yet it still makes a space safer by some measure. So we have another class of system — low-dosage UV-C. And by the way, that type of system would only be enabled by LEDs as opposed to legacy lamps.

So we need new descriptors. “Instantaneous” and “continuous” just are not going to work. There is also the concern that the violet and UV-A systems work on bacteria and not on viruses. In reality, they probably work on viruses, but the time it takes for deactivation may limit the practical use. We need to describe the systems with no ambiguity based on technology used or application scenario. Any ideas?

Maury Wright


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