Germicidal Uv Could Make Airborne Diseases as Rare as Those Carried by Water

If it's re-circulating, it could reduce the spread of germs room to room as has been shown during the pandemic in elderly care facilities. That would be the only use-case I see.

If they put the light in the wrong place it can mess your equipment up.

Can't comment on the price.

There are only a few companies that sell those things at that price point (installed, $600-$800 for the unit), and they’re all so egregiously fraudulent that I strongly considered doing the leg work for a class action lawsuit.

I got the same pitch a few years ago, but as their bad luck would have it I actually worked on a UV-C LED based germicidal system for years with the same goal in mind, albeit as a hobbyist. My focus was on the LED based variants, which dominates new residential products, so I can’t speak to other systems. That said, regardless of the technology a $1,500 UV-C germicidal HVAC system is a $1,500 MRI machine - no it isn’t.

I was extremely interested in how they managed to accomplish what I had deemed unreasonable with current technology, while also being about 1/4 the cost and 1/15th the power requirements. The latter magic claim is their biggest tell, since the power requirements are slapped on the box and the power supply itself. In this case it was ~17 watts. I’d estimated ~300w for a barely reasonable reduction of common pathogens, and that was based on trying to out-clever systems that used 700w+.

Long story short, I disassembled one of them and they’re regular blue-violet LEDs @ ~405nm, a ceramic fragrance diffuser (popular’ish air freshener in the 90’s) that they marketed as some kind of alien tech UV enhancer, and a high voltage ionizer buried deep in the housing. The last item was going to be my cause for action since they proudly claim zero ozone generation while including a device that is solely intended to produce it. Hilariously I actually had a box of the same ionizers and I think I paid $20 for two scoops of them. I believe they include it so they can technically say the device does indeed have some level of potentially measurable germicidal properties, whereas their purple LEDs would have zero. They never claimed the lights were what did it!

They try bank on a technicality and consumer confusion regarding the LEDs by being very careful to say “UV” on the box, not “UV-C”, and due to inefficiencies of not being a laser the spectral wings of ~405nm purple lights would accidentally qualify as emitting UV. I also think there’s probably a legal loophole that allows the minuscule amount of ozone being generated by the literal ozone generator to qualify as “zero” due to dilution, while still being “germicidal” (if they brush up against the electrodes), so they may be skirting the law there as well. I don’t think the totality of their attempt at legal shenanigans would hold up, but I can’t find any other rational explanation for their very specific design and marketing decisions.

That’s as far as I got with it, since I only had a couple hours to inspect the device, but that was more than enough to make up my mind. Final thought: even if they used enchanted technology that fell from space you may only need to consider the 6-8” wide device being installed directly in the ~18” airflow, and restricting it accordingly, to decide if you’d be happier with an external HEPA filter in a couple rooms instead.

I would rather use it in an enclosed apparatus that has a fan to change its air, but only while measuring the ozone level sensitively.

Apologies for my weak google-fu

HEPA is a mature technology with no big improvement curve, but UV treatment is seeing progress.

Ionizing air purifiers make ozone and the makers claim either that it's a good thing or that it's too little to worry about. The first is wrong, the second is a bad sell because the thing it's supposed to be removing is also (by itself) not a big health risk on any single day; the health benefit from removing particles is likely eaten up by the negative health effects of the ozone. You can clean air without ionization, so why? As far as I can tell, it's a pure marketing gimmick, the need to seem high-tech outweighs the actual utility of the thing. (That's also probably why ultrasonic humidifiers are popular, you can see the fog)

They mostly figured it out a couple billion years ago. Cyanobacteria oxidized Earth's surface until the atmosphere was flooded with molecular oxigen, that gets turned to ozone in the stratosphere, filtering most UV. Pretty large engineering feat for a bunch of microbes.

Unlikely for most organism, true

almost every mucosal surface has commensal bacteria which can provide colonization resistance by other bacteria. lungs, skin, vagina, etc..