Of all the lessons society failed to learn from 2020, the importance of clean air is perhaps the most disappointing.
I wear N95 masks on local trains, long distance trains, planes, buses (most of the time), and movie theaters when busy. The few times I haven’t, in particular local train (unfortunately, lots of unhealthy people) and Amtrak, I have gotten sick - strep and covid. Being sick is in some ways not a big deal, but is serious enough I will keep wearing the masks forever. I get sick far less often than my non mask wearing peers.
The tragedy is that the people operating these services - and schools and hospitals - should have installed filters and UV lamps to make this less unnecessary. At least planes have air circulation, the Amtrak trains are an absolute disaster.
Flu is spreading like wildfire right now. With the advent of these and other technologies, that is essentially an opt-in choice society is making. Totally unnecessary. You don’t have to stop many flu cases before a lamp pays for itself.
I'm confused by the handwaving away of the ozone production. It's well established that ozone is toxic. If these are producing it - and it seems to be agreed upon that they are - that's an obvious issue. The suggestion that "you can just filter it with mechanical air filters (activated carbon)" seems strange because you can just filter viruses with mechanical air filters in that case...
I'm a big fan on the idea of improving air quality/reducing viral load in air to improve health. But I'd really prefer to see more of a push towards the "effective quiet (currently DIY) mechanical air filtration systems" the article links to then a technology with obvious and poorly quantified health risks.
From Aerolamps website:
>Does Aerolamp produce ozone? >Yes - but only a very small amount
>Typical indoor ozone levels are 4-6 parts per billions (ppb), while average levels of outdoor ozone are 20-30 ppb - almost all indoor ozone comes from outdoors. Most likely, you will raise your indoor ozone levels much more by opening a window than by operating a far-UVC lamp.
>It's true that in a sealed chamber in a lab, typical far-UVC installations might produce significant (10s of ppb) ozone. However, our indoor spaces aren't sealed chambers. Both theoretical predictions and experimental evidence suggest that Aerolamp will raise indoor ozone levels by no more than 1-2 ppb. Expected ozone increase can also be simulated with Illuminate.
>However, we recognize that ozone is a pollutant, and recommend that Aerolamp should be used with portable air cleaners which include an activated carbon filter. Studies suggest that a single activated carbon filter is more than sufficient to mitigate any far-UVC derived ozone.
I agree that the filter thing doesn't make sense, but it does not seem like this product would meaningfully increase your ozone exposure.
You can filter viruses with mechanical air filters, but based on the available data, far-UVC can do this much faster than even a high-CADR air filter. The best filter I'm aware of can deliver 200 CFM of clean air quietly or 400 CFM loudly, one high-quality far-UV lamp can deliver the equivalent of ~1000 CFM--silently. That seems like the main advantage to me--plus not taking up the floor space that a large, quiet air filter would require. Basically it's the more dakka solution. But it's recommended to use far-UV with at least one source of mechanical air mixing like an air filter anyway just to make sure its maximally effective
It's worth noting that the premise of the article- that low cost Far-UVC could not easily be purchased before the Aerolamp, is false.
While AeroLamp has put a proprietary Ushio emitter in a 3D printed enclosure as a sort of reference model to encourage the use of Ushio components, third party tested Far-UVC has been sold for several years now by Nukit222.com at a fraction of the price of any competitor.
Our approach is somewhat different. We use no IP-encumbered components, all parts that can be purchased from any of a dozen Shenzhen factories, we put the product firmly into the Gongkai ecosystem (https://www.bunniestudios.com/blog/2014/from-gongkai-to-open...) without being at the whim of a single high-cost proprietary central component the manufacturer can reprice at anytime.
By focusing on non-IP-encumbered designs that are basically shanzhai-able-"Temu friendly", and then validating the market for those products, you virtually guarantee it will be picked up, copied and improved upon- meaning lower costs and wider distribution.
If you want to make a fit-for-purpose product, faster, cheaper and at larger scale than the Shenzhen Hardware ecosystem iterating at Shenzhen speed with shanzhai- best of luck to you.
The central remaining issue is safety and efficacy, which is why we post all our third party lab tests, for all our products, for download on the sales page. Ozone output, pathogen chamber tests, full spectral assay for safety and power output, UL CE etc. We were the first company to do this, and push for all companies to do the same.
(author)
I'm really glad that you're making and selling far-UVC products. Nukit is the other manufacturer (aside from Aerolamp) that I feature on https://www.faruvc.org
I really hope that your thesis is correct, and we end up with widespread low cost high quality unencumbered far-UVC. In my looking, though, it seems like bulb life is an issue? Is that right, or have I been snookered by Ushio's marketing?
Well, one reason KrCl lamp life became an issue is that they are not replaceable in any commercially available filtered Far-UVC fixture. Currently, at the end of the KrCl excimer lamp life- typically 3000-5000 hours, you throw the entire Far-UVC device away- filters, ballast, control electronics- the whole thing in the trash. There is some talk of possible refurbishment, but at high cost with no companies really in place offering it.
There's really no excuse for this but planned obsolescence. Replaceable light bulbs are 140-year-old legacy tech and trivial to engineer.
Needless to say, this was a major stumbling block for institutional buyers- having to buy and reinstall ~$5000 worth of Far-UVC for a small room every year or two. At which point virtually every Far-UVC company started claiming everything from 5,000 hours to 20,000 hours operating life- with absolutely no data to support this. Some cite in-house testing, but no real evidence is offered.
Given that fraudulent claims in the Far-UVC industry are common, there's every reason not to trust marketing claims that aren't backed by third-party tests. If you don't have a test that proves it, don't say it. (We urge our customers to trust no one, not even us. "Trust" has no place with potentially dangerous UV devices- everything must be third-party lab tested).
A KrCl excimer lamp that could exceed the current, widely documented 3,000-5,000hr (30% degradation or L70) operating life would be huge news and we'd love to see it. But there would be patents, papers, independent lab tests, some paper trail other than manufacturer claims to support this.
Right now, it's all "trust me bro" marketing with perhaps bit of hedging about possibly using reduced power or limited operating time to increase lamp life. By the time buyers have reached 5,000 hours, the products are well out of warranty, and they are left without recourse. If someone says anything about their Far-UVC lasting more than 5,000 hours, the correct response is "Citation?".
In the absence of any credible data showing that anyone is getting an L70 over 5,000 hours of use in the real world at 100% power and uptime, we've chosen to focus on low-cost, non-IP-encumbered, replaceable bulbs, and all of our future products will use them. Any other manufacturer is welcome to use them as well, with the hope that this will get Far-UVC ownership down to the "rice cooker or oscillating fan" price range needed for those in the most desperate need. Because until everyone is protected, no one is. We're all just a cough and a plane ride from each other.
Yes, you can point this specific UV wavelength at your skin and be fine. People have done extensive animal trials and it is not carcinogenic. Many people have been exposed to a lot of far UVC and nothing bad has happened to them.
Looking right at it might not be good for your eyes.
I feel confident for myself that far UVC is safe.
However, the environments I'd want to use this in are those where many people are gathered. I am not sure whether it is respectful/socially good to use this in those situations (given that far UVC products are not subject to any special regulatory review).
Edit for some additional thoughts:
How does this compare to a air filter?
Pros of UV:
- You are helping support R&D for this very important technology
- Even this Aerolamp DevKit is going to be more cost effective at addressing certain pathogens which are highly susceptible to UV, such as COVID. My guesstimate is that the highest capacity/$ off the shelf air purifier you can buy (https://www.cleanairkits.com/products/brisk-box-ultra-black) has about a third to half of the COVID-removing capacity/$ vs. the Aerolamp DevKit. Ditto for energy efficiency.
- Less maintenance vs. an air filter
- Quietest option
Cons of UV:
- Less energy and cost effective at addressing other microbes, particularly mold
- No ability to address dust, another very important air quality issue
- May make others feel uncomfortable
> Yes, you can point this specific UV wavelength at your skin and be fine.
Not so sure about that: there are microbes on our skin, protecting us from harmful bacteria, funghi and viruses. This lamp would kill those friendly microbes.
It seems a better idea is to put this UV lamp in a duct, and treat only the air that passes through.
>This lamp would kill those friendly microbes.
Not really. Those microbes live deep in your pores where the UV wouldn't reach. Even if the UV totally scoured the surface of your skin, it would only be a temporary disruption, which we're generally ok with. After all lots of things disrupt the skin microbiome--showering, hand sanitizer (which DOES penetrate into the pores).
But I think UV skin microbiome disruption is likely to be pretty mild compared to things like eg hand sanitizer. Generally anything that lives on a surface (compared to liquid, and especially air) requires a much higher UV dose to inactivate, because even seemingly-smooth surfaces actually have lots of microscopic nooks and crannies for pathogens to hide in. And skin isn't smooth at all--it's got tons of visible wrinkles and surface complications and complicated geometry. Bacteria are also less sensitive to far-UV than viruses. So lamps that are dose calibrated to kill airborne viruses aren't going to have much of an effect on bacteria that live on a complex surface.
There's actually some data on this although sadly it never ended up published--my lab collected microbiome data for this 66 week hairless mouse skin exposure study https://pmc.ncbi.nlm.nih.gov/articles/PMC9691791/ and found basically no difference in microbiome between the exposed and unexposed mice. It didn't end up in the paper because nobody in the lab had enough bioinformatics expertise to do a nice publishable analysis and just had to take the bioinformatics centers' word on it that there weren't significant differences. Weak/hearsay-ish evidence but not nothing!
In-duct UV is a thing but it's really not ideal for preventing person-to-person disease transmission, for a number of reasons.
> Many people have been exposed to a lot of far UVC and nothing bad has happened to them. > > Looking right at it might not be good for your eyes. > > I feel confident for myself that far UVC is safe.
This is dangerous misinformation. Like any toxic, it's the Dosis that kills
There are very powerful far UVC products available which will give you sunburn on your skin in a couple of seconds
Somebody blasting UVC in a room of people is crypto monkey level of stupid
This isn't (entirely) new. I did the electronics design for this lamp: https://www.fridotechnologies.com (nb: not affiliated any more, no stake in the business, just a freelancer).
The modules and emitters themselves are still relatively expensive - $200+ - but can be bought from China if you want to DIY a solution.
I am not convinced a single lamp placed over the dining table would provide sufficient irradiance to inactivate viruses and other pathogens in the large room. Consider having an infected individual sneeze or cough at the table. The expiration jet would spread so rapidly. This lamp is like a tiny flashlight placed above the dining table. Furthermore, far UV gets absorbed by oxygen in the air. The net irradiance of far uv is worse than 254 nm at a fixed distance from two equivalent (in power and form) sources.
The lamp would be effective if you were able to quickly circulate the air in the room past the lamp.
I looked it up and Far-UVC (typically 222 nm) seems safe-ish. But how do you confirm it's not outputting 254 nm or other wavelengths in the UVA/B range? Seems likely to happen with sloppy production of sources. You really have to trust the filter on the light or verify the frequency somehow.
(author)
The non-profit OSLUV evaluates lamps and measures their emissions. Here's their evaluation for the Aerolamp, which is the one I've purchased: https://reports.osluv.org/static/assay/aerolamp%20devkit--27...
OSLUV is fantastic; doing great work.
Well, just use your USB spectrometer, of course.
...you do have a USB spectrometer, don't you?
I have mine in my bedside drawer. I use it almost as often as my multimeter.
Does yours measure wavelengths that short? A lot of low cost spectrometers don't, because inexpensive glass and plastic optics transmit visible and near-IR radiation but significantly impair shorter UV wavelengths.
I need to get one :)
I've built 12V mercury vapor UV-C (254nm) lights for fluorescent mineral hunting, and that wavelength is quite harmful, requiring skin and eye protection. Mercury vapor lamps produce a spectrum of wavelengths, also in the visible spectrum, which gets filtered out since it distracts.
According to this [1] article, the 222nm range is safe for exposure, but the Krypton-Chloride bulb in the far-UVC lamp does also produce harmful wavelengths (256nm), therefore a filter is absolutely necessary. Thankfully simple plastics should work fine for that.
I would still be extremely careful deploying these lights in occupied spaces.
Edit: Come to think of it, filtering the harmful UVC (256nm) from KrCl excimer lamps with acrylic would probably also block the far-UVC. Which makes me wonder what material the filter is. Regular glass stops UVC, which is why UVC lamps are usually quartz or special glass formulations.
"What really needs to be understood is that an unfiltered 222nm Far-UV peak from any KrCl excimer lamp emits a wide band of wavelengths starting at 200nm, past the human safe zone of less than 230nm, all the way to the end of the UVC spectrum at 280nm -- with a very worrisome second harmonic peak at 256nm."
"the 222nm excimer lamp's second harmonic peak at 256nm exclusive to KrCl Far-UVC lights should be treated no different than the well-established carcinogenic hazards involved when using 254nm mercury-line UVC germicidal bulbs."
[1] https://www.prweb.com/releases/222-nm-far-uvc-cancer-risk-wi...
What took me by surprise (but really shouldn’t have) with my set of UV A, B, and C flashlights, is how much of the light can get reflected. Pointing at a rock and seeing a spot on my shirt light up was educational.
The filter is a hafnium oxide interference filter! There are some absorption-based filters being studied in academic settings (as they'd be potentially cheaper to manufacture) but none are used commercially as far as I know
Honestly there aren't that many commercially available unfiltered KrCl lamps out there. I'm only aware of one and it's stupid expensive. Every other lamp you can actually buy is filtered, although some filters are a bit worse than others (though still pretty safe). Any lamp module that uses the Ushio Care222 emitter is certainly very well filtered because Ushio integrates the filter into the module.
There are lots of far-UV germicidal lamps. Here's one, from Shenzhen.[1] (This is Naomi Wu's business.)
There are lot of fake ones out there. Especially ones with LEDs. Nobody has a 222nm LED with enough power for this yet.
Someone should make a simple tester. Something that's on the end of a stick, you hold it up near the ceiling, and it lights up:
- Green - enough 222nm light to be effective, not too much other UV.
- Red - too much other UV, light is dangerous.
- Yellow - only "homeopathic" levels of 222nm, ineffective.
You can buy NBS-traceable UV meters, and even a spectrometer, but they're expensive.
[1] https://cybernightmarket.com/products/nukit-lantern-far-uvc-...
Not the same (less safe)
This is incorrent, we've been selling low-cost Far-UVC for quite a bit longer than Aerolamp (they use some of our technology), and it is is proven to be as safe by third-party testing.
Sorry I will correct my post. I agree with you. Far UVC super safe
The spectra are slightly different, but Nukit is also filtered, I would expect it to be just as safe--just lower output
To correct. Far UVC is super safe ;)
Feels like v2 of this will be “ducted” in that it lives next to your air handler and comes on when you are circulating air.
(Like a reef tank sterilizer)
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.
[1] https://levoit.com/collections/humidifiers-diffusers/product...
(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)
I do not believe that there is a good understanding of the impact of far-uvc on plastic embrittlement.
There's research to be done
On the people who are
Still alive.
♫♪
Two studies that I'm aware of, but yeah, data is thin on the ground:
https://www.mdpi.com/2076-3417/13/7/4141 https://www.boeing.cn/cti/downloads/Boeing-Compatibility-of-...
Summarized here, along with other materials considerations: https://blueprintbiosecurity.org/u/2025/06/Blueprint-for-Far...
Along the same lines… where is the proof that as the unit ages it doesn’t leave the magic 220nm range?
It is complete nonsense to point this at people.
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.
It doesn't have to be, but you can avoid any concerns about looking into it or affecting the light quality in the room by doing so.
If you were going to duct it then why wouldn't you just use regular UVC? Much cheaper.
Fair point.
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.
Ducted UV systems for your HVAC exist now, and don't need to bother with the being UVC since the UV doesn't leave the system.
If I recall correctly my furnace guy quoted me less than $2k for a whole house system that attaches to the air intake on my furnace.
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.
> At $500 this is out of (my) Christmas gift range, but I think we're now at the point where dances, churches, offices, rationalist group houses, schools, etc. should consider them.
One of the things in that list gives this away as something you'd see on HN.
no way you're supposed to point it down, right?
Aerolamp insists that it's supposed to be pointed directly at "where people will spend time in the room", including tilting it down.
If it's mounted at the recommended 8.5 feet, it's ~impossible/extremely unlikely for the people in the room to get a dose that exceeds the 222nm threshold limit values set by ACGIH (see here https://uvmedico.com/research-and-publications/acgih-2021-th...). You can be standing around in the lamp's hotspot literally all day and still be fine. Check out this sim tool: https://illuminate.osluv.org/?preview_lamp=Aerolamp%20DevKit
But if you're itchy about direct exposure you can also just leave it horizontally on a high shelf or something and it'll still work pretty well. I see lots of people doing that just because they don't feel like buying mounting equipment. It'll just be more dependent on vertical air currents circulating in the room to work well so be super sure that you have a ceiling fan/HVAC/air filter running while using it. Doesn't need much air movement, just a bit, as long as the room air isn't totally still/stuffy.
Yes you are - at the air that may be contaminated.
Kr-Cl excimer lamps (the only cost effective UVC options currently available, and only manufactured via Ushio) have 2 big drawbacks:
1. Very low efficiency ($/watt and lux/watt) compared to UVA/UVB, such that cleaning a conference room between meetings, for example, results in unacceptable dead time compared to normal UV cleaning.
2. 222nm excimer lamps are a known cancer risk (official as of 2022, if I recall correctly), where the issue is that safety limits (in mW/cm^2 per 8 hour day) are based on theoretical skin absorption over a standard workday given a constant dose. Kr-Cl excimers do not produce a continuous illumination, and this intrinsic characteristic worsens with heat load. Transdermal effects are mediated via hair follicles, and shaved skin permits the greatest dose.
Even if you ignore practical safety concerns and take 1950's guidance as gospel, the time to neutralize covid via 222nm will exceed 60 seconds if the target is at the same distance a person would need to be for allowable safety.
tl;dr just put traditional UV in your hvac ductwork and skip on 222nm.
>Kr-Cl excimer lamps (the only cost effective UVC options currently available, and only manufactured via Ushio)
This is incorrect. Ushio has a patented emitter, but non-IP encumbered Kr-Cl excimer lamps are made and sold in appropriate fixtures at substantially lower cost.
1. UVA/UVB is more efficient in terms of $/watt than 222nm KrCl*, but they're FAR less efficient in terms of germicidal dose than UVC (both 254nm and 222nm). You have to output a LOT of UVA/UVB to kill pathogens at anywhere near the same rate as UVC. I would consider UVA to basically be only "technically" germicidal--it's just not in the same league at all.
2. They're technically considered a cancer risk because UVC is considered "actinic" and so has been grandfathered into that definition, but it actually seems like commonly used UVC wavelengths generally don't penetrate deeply enough into skin to plausibly cause cancer--and you have to keep in mind the difference between 222nm and 254nm. There's definitely no evidence that 222nm is a cancer risk,** but I'm even suspicious of some of the older 254nm studies that report tumors in hairless mice exposed to 254nm. 254nm UVC is produced by low-pressure mercury lamps, and they're *almost* monochromatic, but not quite--they also produce low levels of UVB, which is a serious skin cancer risk even at very low levels (see figure 6 in https://www.tandfonline.com/doi/full/10.1080/10643389.2022.2...). My lab is currently trying to reproduce that result with a filtered/true-monochromatic 254nm lamp and we are just not seeing any tumors in those mice. Those poor bastards are being exposed to such high doses of 254nm that their skin looks super gross, cracked and bleeding, WAY higher doses than anything you'd encounter in a real-world installation--and they're still just not developing tumors. It looks like 254nm is "actinic" in that it's quite unpleasant to experience an overexposure, but it probably doesn't cause cancer, and 222nm seems to not be particularly actinic at all. I get overexposures all the time and basically never notice.
It's also definitely not true that KrCl lamps don't produce continuous illumination. That's exactly what they do!
However, it is true that a typical 222nm installation won't kill covid in 60 seconds. It only reduces it by about 40% in that time period--it'll take about 5 minutes to get to 90% reduction, and 10 minutes to get to 99% reduction. But that is WAY faster than basically any other tech that won't be blowing your hair back, including in-duct UV.
In-duct UV works well for some stuff but not really for person-to-person airborne disease transmission. If it's in the ducts, it's hard to maintain and verify, if the lamps get dusty they stop working (and ducts are super dusty), and anything that goes in the duct only works while your HVAC system is running--and your HVAC system just doesn't run very fast, or else it would be loud as hell. If you're going to put something in your ducts, it should be a MERV-13 filter. Way cheaper, way more maintainable. Then if you want extra air cleaning but don't want to use UV, get portable air filters. I vouch for the reviews at https://housefresh.com/
*although 254nm low pressure mercury lamps are also quite power efficient--about 40% WPE **to be fair, it hasn't been around long enough for long term studies to be done, so if that's your bar for evidence, you'll have to wait--but I think there's other forms of reasonable evidence that can give us information about what's likely a cancer risk and what isn't. The fact that 222nm seems to be >99% absorbed in dead skin cells, and the remaining <1% in non-dividing cells, is pretty strong evidence to me that it's unlikely to cause cancer. Certainly compared to UVB-containing sunlight!*
You can buy UVC LEDs (255nm) for fairly cheap now. $20 or less
that wavelength penetrates the skin. you need to be around 222nm for human safety
uviquity has prototypes of a 220nm solid state chip they’ll commercialize next year (we’re an investor). a single far-uvc photon will destroy the covid virus.
Cool technology, thanks for posting.
The current state of the art UVC (short wave, e.g. 255nm) LEDs have very low efficiency, compared to UVA (long wave, e.g. 365nm). How efficient are these 220nm solid state chips?
Do they emit other frequencies, or are they monochromatic?
The uviquity 220 nm SHG chips are super cool--they're perfectly monochromatic (though maybe with some blue light leakage) and I hear from their tech lead that they expect to get up to 10% WPE. I think that approach is definitely going to be relevant much sooner than far-UVC LEDs, but they're still early days, it's going to be a long road. Krypton-chloride excimer lamps are more or less the only game in town for commercial far-UV, at least for now.
Full report here if you want more solid state far UV info: https://www.convergentresearch.org/resources/convergent/soli...
Yes, however the safety-profile is quite the opposite to 222nm.
This is Far-UVC (typically 222 nm). Regular UVC can cause eye damage.
And skin damage
Evolution has us covered.
Do you know a good source for finding the latest, most efficient LEDs for DIY projects?
Nichia is pretty top of mind for me as a solid supplier of 265-280 nm LEDs https://led-ld.nichia.co.jp/en/product/uv_top.html. Decently high output, decent lifetime (especially the longer wavelengths). There's also CrystalIS https://www.cisuvc.com/klaran-for-disinfection/ But there's tons
This review paper is from 2019, but it includes a good summary of basically everyone who's relevant to the field https://www.nature.com/articles/s41566-019-0359-9 The author used to keep an updated figure on his website but sadly it seems to be down, or have moved
SilannaUV has 230nm, 235nm and 250nm wavelengths, as far as I know the only supplier that does so https://silannauv.com/
I would be pretty careful with all of these wavelengths though. None of them are truly monochromatic far-UV. Use eye/skin protection when messing with them.
This is an affordable 255nm UVC flashlight (buy filter separately due to US patent bs):
https://convoylight.com/products/gray-c8-uvc-255nm-uvb-310nm
Pretty sure that's a UVB flashlight. There's absolutely no way that anyone is selling 255nm UVC that outputs much of anything for more than a few hours for $45.
A good 280nm chip is ~$100 (https://www.ledsupply.com/leds/uv-c-280nm-nichia-ncsu334a-le...), and it gets exponentially harder to produce shorter wavelengths the further down the spectrum you go. 270nm and 265nm chips are getting there, but 255nm is mostly a research area right now.
My guess is if we don't get a better vaccine, the COVID issue will probably be mostly or partially solved when 222nm UV-C LEDs become relatively efficient and low cost. At that point they will be mandated in public places.
I don't really think 222nm UVC LEDs are going to be super relevant anytime soon https://www.convergentresearch.org/resources/convergent/soli...
SHG chips might get there but they're very early days right now. And solid state capital economics are pretty unforgiving--I think we'd have to be seeing millions of lamp sales annually for SHG to really compete with KrCl lamps
Honestly, the KrCl lamps currently available are already pretty cheap even at the very small scale they're being sold. If demand picked up I think they could easily fall from $500/lamp to $100/lamp without any serious innovation.
It would be awesome if SHG could beat that and I think it has tons of advantages, but white LEDs got as cheap and efficient as fast as they did because literally everybody needs lightbulbs and they used to consume a lot of energy--general lighting is a huge industry with tons of demand. UVC simply is not.
I hadn't heard about the SHG platform. Thanks for the link!
It feels like this would backfire.
I mean, UV light is carcinogenic, and environments that are way too clean, are fine for surgery or manufacturing semiconductors, but for most humans (specially children) they can be counter-productive.
The immune system needs something to train on and fight, otherwise you end up with autoimmune diseases and all sorts of crap.
We're essentially walking ecosystems that can easily be imbalanced.
>> The immune system needs something to train on and fight, otherwise you end up with autoimmune diseases and all sorts of crap.
If you want to train your childrens' immune system, get a dog. Don't intentionally expose them to pathenogenic viruses like COVID or the flu. https://www.science.org/content/article/want-fight-allergies...
Far UVC is not carcinogenic (most UV is, this is just a specific wavelength that isn't).
Ideally you'd want to use these lamps in environments that our immune systems didn't evolve for, like crowded conference rooms and school classrooms.
Far UVC is carcinogenic when it reaches living tissue. However, it has a very short mean free path so it doesn't, generally, reach the growing layer of skin. It's less obvious whether exposed mucus membranes (lips, nose, tongue) or the eyes are affected. It probably doesn't reach the lens of the eye, which is good.
I think that is the same thing as saying that Far UVC is non-carcinogenic.
Ok… but hear me out…
Hey guys, look you can treat everyone at Thanksgiving with one for $500, and bonus might not be carcinogenic if it is made correctly!
There is a small watery layer covering your cornea, this is enough to impede far UV-C (~222nm is safe, 254nm regular UV-C is dangerous to your eye!)
The best training for immune robustness is going outside and get exposure to a wide range of stuff. But for indoor spaces, air quality is going to be dominated by the microbes and viruses of the people in the space itself. For public spaces and shared residential spaces with poor airflow this would be great - grocery stores, nursing homes, etc. For condos, apartments, SFH, etc. it's probably less necessary, but probably wouldn't hurt. Or nice to have when company comes over, or someone in the house is sick and "polluting" the air.
Not the same wavelength as UV. This wavelength is blocked by your skin - and outer layer of your eyeballs!
Leaving UVC sources exposed to eyesight is completely irresponsible. Please don't do this.
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This absolutely depends on the frequency of UVC and the intensity of the lamp. The lamps this post links such as https://aerolamp.net are putting out 222-nm, which is much safer than longer UVC wavelengths and the intensity is well under TLV when placed 8.5ft up (or higher).
See https://www.faruvc.org for more on eye safety.
They can leak into higher wavelengths. You are really putting a whole lot of trust in manufacturers if you are sitting underneath one of these for decades with unprotected eyes. Not a risk I would take personally (I have glaucoma already, so I'm a bit more sensitive than the average person about eye health)
Ah nice, their data sheet has a spectrum. Kind of odd that they don't market the "we filter out the harmful parts" feature more prominently.
Many manufacturers refuse to post third party spectral assays detailing safety and power output, it's a big problem.
Kinda like advertising "Asbestos-Free Cereal" isn't it? If someone was marketing a product to me and they were super insistent about how super duper safe it was I would probably start getting suspicious
This is not UVC - this is Far UVC and is blocked by the outer layer of your eyeball, so it is safe. https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/
Far-UVC and Eye Safety: Findings from a 36-Month Study - https://uvmedico.com/news/far-uvc-and-eye-safety - January 16th, 2025
> Far-UVC is a type of ultraviolet light emitted at a 222 nm wavelength that effectively deactivates microorganisms. Unlike traditional UVC light at 254 nm, Far-UVC doesn’t penetrate the outer dead layer of skin or the outer layer of the cornea, making it safe for use around people while maintaining powerful germicidal properties.
> The 222 nm wavelength is unique in its ability to decontaminate without causing harm when used within regulatory limits. Unlike longer UV wavelengths, it interacts only with the outermost layers of the skin and eyes, which naturally renew themselves. This makes it ideal for continuous decontamination in occupied spaces, as confirmed by the 36-month clinical study showing no adverse effects even after daily exposure.
References:
https://www.faruvc.org/ (disclosure: this is published by the same author as this post)
Sugihara K, Kaidzu S, Sasaki M, Ichioka S, Sano I, Hara K, Tanito M. Ocular safety of 222-nm far-ultraviolet-c full-room germicidal irradiation: A 36-month clinical observation. Photochem Photobiol. 2024 Dec 10. https://doi.org/10.1111/php.14052 Epub ahead of print. PMID: 39659140. https://onlinelibrary.wiley.com/doi/10.1111/php.14052
Sugihara K, Kaidzu S, Sasaki M, Tanito M. Interventional human ocular safety experiments for 222-nm far-ultraviolet-C lamp irradiation. Photochem Photobiol. 2024 Aug 19. https://doi.org/10.1111/php.14016 Epub ahead of print. PMID: 39161063. https://onlinelibrary.wiley.com/doi/10.1111/php.14016
Buonanno M, Hashmi R, Petersen CE, Tang Z, Welch D, Shuryak I, Brenner DJ. Wavelength-dependent DNA damage induced by single wavelengths of UV-C radiation (215 to 255 nm) in a human cornea model. Sci Rep. 2025 Jan 2;15(1):252. https://doi.org/10.1038/s41598-024-84196-4 PMID: 39747969; PMCID: PMC11696903. https://www.nature.com/articles/s41598-024-84196-4
Interesting study. Only four people though, and the lamps were "carefully calibrated" so exposure was within a safety threshold. I've seen some lamps have safety interlocks that attempt to turn off the light if people get too close. I don't think UVC will be practical for most settings as long as it needs this kind of caution.
If we could establish a higher safety threshold so that we could be sure it wouldn't harm humans even if they were very close to the lamp, that would be great. Then we could deploy it in almost any public or private space.
I think that blog post is mostly just an AI summary of one or more of those studies.
Noted, it was included for completeness after I had independently found the resources I enumerate.
FYI, all three of the studies are funded by UV light manufacturers: Ushio Inc (first two, 100%), and LumenLabs (last one, partially).
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You are not an expert on optical safety and should not make sweeping, generalized statements as though you were.
I am an optical engineer, but don't specialize in eye-safe studies, and I wouldn't dare make a statement without consulting safety guidelines. The eye's sensitivity to wavelengths is exponentially variable, and very specific about some cutoffs - moreso than most biological phenomena, because the limiting factors are bandgaps of molecules, not cell structures.
> I wear N95 masks on local trains, long distance trains, planes, buses (most of the time), and movie theaters when busy. The few times I haven’t, in particular local train (unfortunately, lots of unhealthy people) and Amtrak, I have gotten sick - strep and covid. Being sick is in some ways not a big deal, but is serious enough I will keep wearing the masks forever. I get sick far less often than my non mask wearing peers.
I used to get sick when I went into the city. Once I started commuting, it happened a lot less as I built up immunity. I'm not saying everyone should lick doorknobs for maximum health.
Anyways, I got to a lot of shows as well, and wearing masks is joyless. I wear them when I'm feeling sick, to reduce the range of transmission (although I just try and stay home)
That said, for institutions where there are sick and weak people, it's almost criminal that they aren't investing even more heavily in testing these sort of technologies.
> Once I started commuting, it happened a lot less as I built up immunity.
To give another anecdotal evidence: before COVID I used to catch 3 to 4 colds per year. Winter was basically a nightmare season where I was always living in fear of when I would get sick next. After COVID I started wearing an N95 in populated places. As a result, I went to 0 cold per years instead of getting sick even more often because of the additional virus in town. Now I feel I can live normally in winter without always worrying of getting sick and I always feel healthy.
I tried switching to a regular surgical mask (and in general being less careful) to try to find a good middle ground between cost, appearance and protection; while I did not catch colds I did get COVID at the same time as unmasked people around me, so I'm back to N95s (this was likely following something like hours and hours of continuous exposure so makes sense a leaky surgical mask did not prevent it). (my bout of covid was quite mild fortunately; but first time being mild does not mean future ones will be or won't lead to long-term symptoms).
Some people told me that wearing masks will "weaken" my immune system, I still need to see that; after two/three years I just feel healthy and this is refreshing after decades of getting sick all the time.
Plus, instead of the advice of "cook your own food to eat well, sleep well, do sports" that probably requires something like 28 hours per day with a standard-issue job while likely not being as effective as respiratory protection, putting a mask on takes only 30 seconds per day. That's probably good general advice anyway, but not the shortest path to solving the "getting sick often" problem.
> I wear them when I'm feeling sick, to reduce the range of transmission (although I just try and stay home)
I really, really wish more people would do this. If you are feeling sick and need to go out into public, put on a mask. This is doubly true especially if you need to take a plane flight. I understand that you probably can't reschedule your plane flight for a lot of reasons, but, for the love of God, if you're hacking up a lung on an airplane put on a damn mask.
Have some common courtesy.
masks suck. life is risky. but they're a tool and an important one.
We also have found out that Covid decays less quickly in air with high CO2. So highly polluted areas and poorly ventilated ones compound the problem by trapping CO2 in and allowing the virus to survive longer in the air. That is very likely the case for other viruses as well as it impacts the aerosols.
That's really interesting; I had thought it was just the high CO2 was a proxy for greater occupancy, but it does look like there is a physical effect.
https://www.nature.com/articles/s41467-024-47777-5
Yes, it's due to changing the pH of water in the air.
ChangeTheAirFoundation.org
Does everyone know how often their peers fall sick? I’ve had maybe two illnesses in the last five years and I don’t do all this. In fact, I was masks off as soon as we were allowed to, traveled often via plane and train. I also was at many EDM shows as soon as they opened up.
I used to wear masks whenever I fell sick but it’s been a while. After the pandemic, though, everyone started using these as political symbols and I want to opt out of that personally. A thing I’d been doing for decades is suddenly some kind of statement. I’ve no problem looking out for others but if there’s enough schoolmarming over this, I might just not.
I think people are neurotic about this stuff but probably the reality is that others fall sick often and need to take these precautions and I don’t and therefore see no need to.
At the population level, if it’s worth it, then that’s fine but I think it’s not a given that these things are worth it.
I used to get sick a lot more often, pretty consistently 3-4 times per year. Since I’ve started masking on trains (specifically because others who are sick and coughing aren’t wearing a mask) and other things (elderberry, zinc, NAC at signs of cold) I’ve gone down to 1-2 times per year. And that is mostly from hooking up with people who had COVID and didn’t realize it.
It’s hard to say exactly what led to the reduction in illnesses, but the N95 masks have the strongest evidence base of the interventions I’ve tried.
It is a given these things are worth it, as long as they're done properly.
https://www.researchgate.net/figure/Reduction-in-infection-r...
That paper is about mandatory masking and social distancing at the population level. It does not speak to the question of whether it's "worth it" to wear a mask on the train if you're the only one who is doing it.
I incidentally reviewed my medical journal today and had ONE infection since 2018 (which in all likelihood was an enterovirus). ONE. What a bit of awareness will do for you and your immune system! Not just no sars2 but nothing else either.
TWO YEARS (not to mention a trillion and a half usd and eur) wasted on "handwashing" against an airborne virus plus all the other crap that came along with this betrayal or was it utter stupidity I still cant tell which.
When Elon the Shithead announced the Tesla Biohazard filter for China, I was annoyed.
Our Public Transports AC is so shit, that in a hot summer, the outside is cooler than the full SBahn.
And a single Car! Had such a good air filter in comparision.
I primarily communte by car now after the office moved and i'm def less often sick.