The advantage of far UVC over other UV air cleaning solutions is that it doesn't need to be ducted. This means that you can kill microbes right when they leave someone's mouth - you don't need to wait for them to be sucked through an air handler.
I'm curious if plastics embrittlement is a problem with Far-UVC. I recently was putting a large evaporative humidifier [1] through its paces for someone to get my opinion, and a challenge was that you had to clean the water tank that was the foundation of the unit fairly frequently (every few days). I provided feedback to the manufacturer that a far UVC bulb in the tank might be useful for reducing cleaning intervals.
For use cases where the emissions are contained (HVAC, water tanks, etc), I think it's a slam dunk from an electronic antiseptic perspective. UV is somewhat common in water filtration today, but perhaps an improvement is possible if these bulbs last longer than existing UV solutions.
(I do not recommend the humidifier by the way, simply too much work to keep the water tank and the evaporation panels clean, I recommend an ultrasonic version instead)
This is a study of the Ushio Care222 unit, but its underlying physics is the same as any other KrCl excimer lamp, so its pretty implausible for other KrCl lamps to exhibit spectral drift when this one doesn't.
The spectrum does change a bit over time--it actually gets less dangerous. But it's a very slight difference.
So different hardware, a clinical unit designed for thousands of hours.
Vs a very likely Shenzen unit that a teeny tiny group is selling on a basic website. And, you can make zero claims on whether a light spectrum of a led will go up or down over time despite one example. Amplifiers/voltages, coatings wearing down, oxide layers in diodes breaking down, etc.
I'm not sure what you mean by clinical unit--the ushio care222 is the longest lasting KrCl emitter I'm aware of, but as all bulbs age, they tend to degrade just by losing output, not by spectral shifting.
Basically everyone in far-UVC is a teeny tiny group selling lamps on basic websites, even those who source care222 emitters from USHIO. It's not a big industry!
We don't source our KrCl bulbs from Shenzen, but not for this reason. Yes, that's true about LEDs, but the physics of LEDs and excimer bulbs are different. Excimer spectra don't smoothly shift the way LED spectra do. Excimer spectra have characteristic peaks based on the energy levels of the possible gas molecule species present in the filler gas. The main change over time is the gradual reduction of the 259nm Cl2* peak, which is the main peak of concern--so it fails gracefully.
Another possibility is the degradation of the dichroic filter coating under thermal stress--but I've only ever observed this in diffused units, none where the filtered glass is open to the air, and that will happen even on an Ushio bulb.
Nukit is our competitor but I doubt very much that any concerning spectral shift will take place over the course of the lifetime of their lamp.
A ducted system seems like it kills a lot of the pros of this system compared to just putting an (effective, i.e. merv-13+) air filter in the ducted system to catch the viruses. And also other things that are bad for you like particles small enough to get where they shouldn't in your lungs.
Nah--use 254nm for that. It's a standard thing, if it's contained in a duct it doesn't need to be fancypants human-safe 222nm.
Ducting it kills most of the effectiveness though--now you have to move air through your ducts in order to treat it, so you only get as much treatment as you move air--usually not very fast or else it would be loud and annoying. You can move it faster, but then you need more UV since the faster-moving air won't be exposed for as long. Honestly, upgrade to a MERV-13 filter before thinking about residential in-duct UV
In-room UV is a different story--since it exposes all room air, pathogens start getting inactivated as soon as they're exhaled. The whole room becomes a disinfection reactor.