Besides this, excimer lamps have a low expected lifetime, of both the light source as well as the filter due to the high energy in the UV photons. This makes replacement (and maintenance cost) a real risk. This could be remedied by similar wavelength LEDs from companies like CrystalIS but these are expensive and very low power (only work germicidal on a short distance).
Prof. Brenner at Columbia University has first foreseen applications of 222nm in operating rooms, to prevent infection during surgery.
On the whole, it would need significant investment in both research, certification and risk analysis for this to become commercially viable, so while some of the technology is there, the market demand so far just is not -- post-pandemic.
Especially since you could probably get more mileage out of the same amount of light energy by forcing the air through a narrower passage, since only airborne particles are actually going to absorb any energy anyway, and air is mostly just empty air.
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.
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.
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.
Can't comment on the price.
And then the simple expedient of useing radiant heat sources, that while not as lethal as UV, are in fact quite deadly to bacteria and anything tiny with a high water content, but completly harmless to humans and ,animals,plants. Couple this with hard, smooth ,surfaces that are designed so that there no crevices or areas filth can acumulate, useing hard woods,glass,tile,metal,leather/vinyl l,high gloss paint,for surfaces. No cloth, no carpet.While not exactly cosy or friendly, it makes getting home that much nicer. Cheap, reliable, low maintenence, implimentable at scale, now.
Apologies for my weak google-fu
Viruses and bacteria aren't the only bad things you don't want in your air. Ozone is thought to be a carcinogen in its own right and aggravate the health effects of particulate pollution. We want filtering and air circulation anyway, we don't want anything that makes it worse. The consumer electronics industry is all too willing to try to sell us things that make our problems worse, such as ultrasonic humidifiers, or ionizing air purifiers with special chambers for your aromatherapy oils, so it's best to be careful.
What is bad about these?
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)
Limiting the wavelength helps with humans, but adds a lot of cost.
It might be effective to have a box that draws in air (with a fan, most likely) and the UV source shines within. The inputs and outputs would need to have a few turns and have surface treatments to reduce the amount of uv ligh that can escape. You would have some fan noise though.
HEPA is a mature technology with no big improvement curve, but UV treatment is seeing progress.
I had to do a bunch of safety research and testing. We had some grower partners experimenting with it too and they had their workers operate the system without any coverings and everyone got sunburn. Unbelievable.
Another startup working on this right now is TRIC robotics.
[1] https://cybernightmarket.com/products/mini-far-uvc-lights-se...
Unlikely for most organism, true
I think the microbes are still trying to figure this one out.
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.
What about beneficial and neutral but important bacteria and viruses? "Air" is actually a complex soup of all types of things. This like applying HCl to a skin infection.
For example, the gut microbiome is in flux for about the first 3 years of life, and thereafter it's mostly only the relative abundances of different microbes that shift in response to diet, you need something like antibiotics or severe diarrhea to actually induce permanent changes (usually for the worse).
Compared to that, there really aren't many microbes in the air. For children, it could very possibly be bad, but even then I'd expect most of their microbial input to come from their parents, food, and surfaces. Which are already grossly deficient compared to old-school rural settings, but I'm not sure if germicidal UV would make it worse.
[1] but who am I, it would still be worthwhile to check obviously
Such as what? There are some located in the gut, but pretty much everything else out there is in conflict with our immune system.
almost every mucosal surface has commensal bacteria which can provide colonization resistance by other bacteria. lungs, skin, vagina, etc..
So yeah, I don't know. I think you have a point here.
a moderate amount of UV stimulates vitamin D production, suppresses inflammation, and turns on DNA repair pathways
In fairness to the article, ventilation was mentioned, but also quickly dismissed. The 60% efficiency figure quoted for ERV is also a bit on the low side for many contexts. And sure, ERV fans themselves use some power (say 50W) but that's about what you'd use in a decent size room with some UV lamps and a fan.
