6 ms·

You Can Just Buy Far-UVC

80 points by surprisetalk 10mo ago

joezydeco 10mo ago
Leaving UVC sources exposed to eyesight is completely irresponsible. Please don't do this.
- toomuchtodo 10mo ago
  Far-UVC and Eye Safety: Findings from a 36-Month Study - https://uvmedico.com/news/far-uvc-and-eye-safety 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/ 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 https://doi.org/10.1111/php.14052 Epub ahead of print. PMID: 39659140. https://onlinelibrary.wiley.com/doi/10.1111/php.14052 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 https://doi.org/10.1111/php.14016 Epub ahead of print. PMID: 39161063. https://onlinelibrary.wiley.com/doi/10.1111/php.14016 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 https://doi.org/10.1038/s41598-024-84196-4 PMID: 39747969; PMCID: PMC11696903. https://www.nature.com/articles/s41598-024-84196-4 https://www.nature.com/articles/s41598-024-84196-4
  - roywiggins 10mo ago
    I think that blog post is mostly just an AI summary of one or more of those studies.
    - toomuchtodo 10mo ago
      Noted, it was included for completeness after I had independently found the resources I enumerate.
  - modeless 10mo ago
    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.
  - daveguy 10mo ago
    FYI, all three of the studies are funded by UV light manufacturers: Ushio Inc (first two, 100%), and LumenLabs (last one, partially).
    - Nukit 10mo ago
      [dead]
- jefftk 10mo ago
  (author) This absolutely depends on the frequency of UVC and the intensity of the lamp. The lamps this post links such as https://aerolamp.net 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 https://www.faruvc.org for more on eye safety.
  - the8472 10mo ago
    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.
    - Nukit 10mo ago
      Many manufacturers refuse to post third party spectral assays detailing safety and power output, it's a big problem.
    - vbelenky 10mo ago
      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
      - the8472 10mo ago
        UV rightfully raises concerns about skin damage, highlighting that they're careful about excluding the harmful parts would be helpful for customers who either know just enough to think "UV bad" or to those who wonder how narrow their filters are. Imo a better analogy would be selling a circular saw with a safety mechanism and hiding the latter in the specsheet.
      - gs17 10mo ago
        No, it's more like advertising asbestos-free talc.
  - trashface 10mo ago
- IAmBroom 10mo ago
  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.
  - Retz4o4 10mo ago
    https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/
    - IAmBroom 10mo ago
      Retz, I was replying to the same post you were. You were not the problem.
- Retz4o4 10mo ago
  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/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/
throawayonthe 10mo ago
no way you're supposed to point it down, right?
- gs17 10mo ago
  Aerolamp insists that it's supposed to be pointed directly at "where people will spend time in the room", including tilting it down.
  - vbelenky 10mo ago
    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-threshold-limit-values-tlvs-and-biological-exposure-indices-beis 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 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.
- Retz4o4 10mo ago
  Yes you are - at the air that may be contaminated.
lbotos 10mo ago
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)
- elil17 10mo ago
  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.
  - toomuchtodo 10mo ago
    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/products/superior-6000s-smart-evaporative-humidifier-2026 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)
    - elil17 10mo ago
      I do not believe that there is a good understanding of the impact of far-uvc on plastic embrittlement.
      - toomuchtodo 10mo ago
        Delightful, an experiment to be run!
juancn 10mo ago
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.
- elil17 10mo ago
  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.
  - scythe 10mo ago
    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.
    - elil17 10mo ago
      I think that is the same thing as saying that Far UVC is non-carcinogenic.
      - gpm 10mo ago
        I actually read it as saying far UVC is probably carcinogenic for specific areas of your body (lips, maybe eyes). I don't know if that's true, but it's what GP suggests to me.
        SV_BubbleTime 10mo ago
        Ok… but hear me out… Hey guys, look you can treat everyone at Thanksgiving with one for $500, and bonus might not be carcinogenic if it is made correctly!
elil17 10mo ago
Yes, you can point this specific UV wavelength at your skin and be fine. People have done extensive animal trials and it is not carcinogenic. Many people have been exposed to a lot of far UVC and nothing bad has happened to them. Looking right at it might not be good for your eyes. I feel confident for myself that far UVC is safe. However, the environments I'd want to use this in are those where many people are gathered. I am not sure whether it is respectful/socially good to use this in those situations (given that far UVC products are not subject to any special regulatory review). Edit for some additional thoughts: How does this compare to a air filter? Pros of UV: - You are helping support R&D for this very important technology - Even this Aerolamp DevKit is going to be more cost effective at addressing certain pathogens which are highly susceptible to UV, such as COVID. My guesstimate is that the highest capacity/$ off the shelf air purifier you can buy (https://www.cleanairkits.com/products/brisk-box-ultra-black 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
- amelius 10mo ago
  > 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.
  - vbelenky 10mo ago
    >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/ 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.
gpm 10mo ago
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.
- elil17 10mo ago
  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.
- vbelenky 10mo ago
  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
car 10mo ago
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-with-unfiltered-far-uv-c-222-excimer-krcl-krypton-chloride-excilamps-claims-far-uvc-test-card-manufacture-quantadose-846680638.html https://www.prweb.com/releases/222-nm-far-uvc-cancer-risk-wi...
- Modified3019 10mo ago
  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.
- vbelenky 10mo ago
  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.
n8cpdx 10mo ago
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.
- Fazebooking 10mo ago
  [flagged]
- HSO 10mo ago
  [flagged]
  - akarlsten 10mo ago
    Do you go to the doctor if you get a cold? Why would these things show up in your medical journal?
    - HSO 10mo ago
      Why would I need a medical doctor to write things down in a journal?
- PaulKeeble 10mo ago
  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.
nmaleki 10mo ago
You can buy UVC LEDs (255nm) for fairly cheap now. $20 or less
- briandw 10mo ago
  This is Far-UVC (typically 222 nm). Regular UVC can cause eye damage.
  - jefftk 10mo ago
    And skin damage
    - car 10mo ago
      Evolution has us covered. https://pmc.ncbi.nlm.nih.gov/articles/PMC3010660/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3010660/
- deleted 10mo ago
  [deleted]
- miduil 10mo ago
  Yes, however the safety-profile is quite the opposite to 222nm. https://www.larsonelectronics.com/news/1763 https://www.larsonelectronics.com/news/1763 https://uvmedico.com/far-uvc-light https://uvmedico.com/far-uvc-light
- car 10mo ago
  Do you know a good source for finding the latest, most efficient LEDs for DIY projects?
  - vbelenky 10mo ago
    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 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/ 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 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/ 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.
api 10mo ago
> 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.
briandw 10mo ago
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.
- jefftk 10mo ago
  (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--27c4ca60-0da7-4669-8cc7-36746a06fb62--R00.html https://reports.osluv.org/static/assay/aerolamp%20devkit--27...
  - Retz4o4 10mo ago
    OSLUV is fantastic; doing great work.
- Bad_Initialism 10mo ago
  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.
  - briandw 10mo ago
    I need to get one :)
  - philipkglass 10mo ago
    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.
  - ansgri 10mo ago
    Do you have a recommendation for an inexpensive one? I’ve worked with OceanOptics Flame series, but they’re not exactly cheap, and their software was crap.
Animats 10mo ago
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-light https://cybernightmarket.com/products/nukit-lantern-far-uvc-...
- Retz4o4 10mo ago
  Not the same (less safe)
  - Nukit 10mo ago
    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.
    - Retz4o4 10mo ago
      Sorry I will correct my post. I agree with you. Far UVC super safe
  - vbelenky 10mo ago
    The spectra are slightly different, but Nukit is also filtered, I would expect it to be just as safe--just lower output
  - Retz4o4 10mo ago
    To correct. Far UVC is super safe ;)
ralphonzathew 10mo ago
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.
- vbelenky 10mo ago
  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/10.1080/10643389.2022.2084315#d1e987 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/ 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!*
deleted 10mo ago
[deleted]
tehjoker 10mo ago
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.
- vbelenky 10mo ago
  I don't really think 222nm UVC LEDs are going to be super relevant anytime soon https://www.convergentresearch.org/resources/convergent/solid-state-far-uvc-roadmapping-workshop-report 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.
  - tehjoker 10mo ago
    I hadn't heard about the SHG platform. Thanks for the link!
nippoo 10mo ago
This isn't (entirely) new. I did the electronics design for this lamp: https://www.fridotechnologies.com 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.
Nukit 10mo ago
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-source/ 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.
- jefftk 10mo ago
  (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 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?
  - Nukit 10mo ago
    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.
dskhatri 10mo ago
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.
- vbelenky 10mo ago
  Yeah, what responsibly deployed far-UV is definitely not is an instant kill beam that immediately inactivates exhaled pathogens. I estimate it takes 100 mW of far-UV about 5 minutes to inactivate 90% of the flu/covid in a 250 sqft room (10 minutes to get to 99%), assuming the air is well-mixed. Far-UV should be thought of as a super-powerful quiet air filter more than anything else--it prevents infectious aerosols from building up in a space, which can matter a lot. You don't necessarily immediately get infected just because someone infected coughed near you--you might only get infected if you spend a long time near them, sharing their air. Continuously cleaning the air prevents these kinds of infections, and can make the infections that do still happen less severe. You're totally right that circulating the air is important though! Definitely don't use far-UV in totally still air. But you don't necessarily need a LOT of air movement to achieve "good" mixing. Often just an air-change or so of ventilation is enough--just think about what would happen if you started smoking indoors. The smoke would be ~everywhere pretty fast. The oxygen absorption at 222nm is not significant however--it's enough to produce a bit of ozone (less than you'd get from just opening a window), but not enough to actually absorb a significant amount of radiation. 222nm lamps are generally less powerful than 254nm lamps anyway, but because 254nm is much less safe, those systems have to be deployed in ways that often reduce their efficacy--in special louvred fixtures that kill most of their output or in portable units/ducts that constrain their effectiveness. 222nm seems to be more effective per-photon at inactivating viruses than 254nm too: https://pubs.acs.org/doi/10.1021/acs.est.3c08675 https://pubs.acs.org/doi/10.1021/acs.est.3c08675
tetromino_ 10mo ago
Before buying something like this for my home, I'd need to know: * Is it safe for babies and small children (whose thin skin and developing eyes might well be much more vulnerable to UVC) * Is it actually safe for all adults regardless of skin type, colors, dermatologic conditions, or was it only tested on a few healthy college students of one particular ethnicity; * Does it accelerate degradation of household items, plastics, fabrics, books, and paint; and if so, by how much

80 points by surprisetalk 10mo ago

joezydeco 10mo ago

Leaving UVC sources exposed to eyesight is completely irresponsible. Please don't do this.

toomuchtodo 10mo ago
Far-UVC and Eye Safety: Findings from a 36-Month Study - https://uvmedico.com/news/far-uvc-and-eye-safety 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/ 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 https://doi.org/10.1111/php.14052 Epub ahead of print. PMID: 39659140. https://onlinelibrary.wiley.com/doi/10.1111/php.14052 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 https://doi.org/10.1111/php.14016 Epub ahead of print. PMID: 39161063. https://onlinelibrary.wiley.com/doi/10.1111/php.14016 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 https://doi.org/10.1038/s41598-024-84196-4 PMID: 39747969; PMCID: PMC11696903. https://www.nature.com/articles/s41598-024-84196-4 https://www.nature.com/articles/s41598-024-84196-4
- roywiggins 10mo ago
  I think that blog post is mostly just an AI summary of one or more of those studies.
  - toomuchtodo 10mo ago
    Noted, it was included for completeness after I had independently found the resources I enumerate.
- modeless 10mo ago
  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.
- daveguy 10mo ago
  FYI, all three of the studies are funded by UV light manufacturers: Ushio Inc (first two, 100%), and LumenLabs (last one, partially).
  - Nukit 10mo ago
    [dead]
jefftk 10mo ago
(author) This absolutely depends on the frequency of UVC and the intensity of the lamp. The lamps this post links such as https://aerolamp.net 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 https://www.faruvc.org for more on eye safety.
- the8472 10mo ago
  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.
  - Nukit 10mo ago
    Many manufacturers refuse to post third party spectral assays detailing safety and power output, it's a big problem.
  - vbelenky 10mo ago
    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
    - the8472 10mo ago
      UV rightfully raises concerns about skin damage, highlighting that they're careful about excluding the harmful parts would be helpful for customers who either know just enough to think "UV bad" or to those who wonder how narrow their filters are. Imo a better analogy would be selling a circular saw with a safety mechanism and hiding the latter in the specsheet.
    - gs17 10mo ago
      No, it's more like advertising asbestos-free talc.
- trashface 10mo ago
IAmBroom 10mo ago
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.
- Retz4o4 10mo ago
  https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/
  - IAmBroom 10mo ago
    Retz, I was replying to the same post you were. You were not the problem.
Retz4o4 10mo ago
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/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/

throawayonthe 10mo ago

no way you're supposed to point it down, right?

gs17 10mo ago
Aerolamp insists that it's supposed to be pointed directly at "where people will spend time in the room", including tilting it down.
- vbelenky 10mo ago
  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-threshold-limit-values-tlvs-and-biological-exposure-indices-beis 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 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.
Retz4o4 10mo ago
Yes you are - at the air that may be contaminated.

lbotos 10mo ago

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)

elil17 10mo ago
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.
- toomuchtodo 10mo ago
  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/products/superior-6000s-smart-evaporative-humidifier-2026 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)
  - elil17 10mo ago
    I do not believe that there is a good understanding of the impact of far-uvc on plastic embrittlement.
    - toomuchtodo 10mo ago
      Delightful, an experiment to be run!

juancn 10mo ago

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.

elil17 10mo ago
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.
- scythe 10mo ago
  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.
  - elil17 10mo ago
    I think that is the same thing as saying that Far UVC is non-carcinogenic.
    - gpm 10mo ago
      I actually read it as saying far UVC is probably carcinogenic for specific areas of your body (lips, maybe eyes). I don't know if that's true, but it's what GP suggests to me.
      - SV_BubbleTime 10mo ago
        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!

elil17 10mo ago

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 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

amelius 10mo ago
> 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.
- vbelenky 10mo ago
  >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/ 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.

gpm 10mo ago

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.

elil17 10mo ago
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.
vbelenky 10mo ago
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

car 10mo ago

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-with-unfiltered-far-uv-c-222-excimer-krcl-krypton-chloride-excilamps-claims-far-uvc-test-card-manufacture-quantadose-846680638.html https://www.prweb.com/releases/222-nm-far-uvc-cancer-risk-wi...

Modified3019 10mo ago
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.
vbelenky 10mo ago
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.

n8cpdx 10mo ago

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.

Fazebooking 10mo ago
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HSO 10mo ago
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- akarlsten 10mo ago
  Do you go to the doctor if you get a cold? Why would these things show up in your medical journal?
  - HSO 10mo ago
    Why would I need a medical doctor to write things down in a journal?
PaulKeeble 10mo ago
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.

nmaleki 10mo ago

You can buy UVC LEDs (255nm) for fairly cheap now. $20 or less

briandw 10mo ago
This is Far-UVC (typically 222 nm). Regular UVC can cause eye damage.
- jefftk 10mo ago
  And skin damage
  - car 10mo ago
    Evolution has us covered. https://pmc.ncbi.nlm.nih.gov/articles/PMC3010660/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3010660/
deleted 10mo ago
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miduil 10mo ago
Yes, however the safety-profile is quite the opposite to 222nm. https://www.larsonelectronics.com/news/1763 https://www.larsonelectronics.com/news/1763 https://uvmedico.com/far-uvc-light https://uvmedico.com/far-uvc-light
car 10mo ago
Do you know a good source for finding the latest, most efficient LEDs for DIY projects?
- vbelenky 10mo ago
  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 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/ 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 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/ 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.

api 10mo ago

> 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.

briandw 10mo ago

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.

jefftk 10mo ago
(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--27c4ca60-0da7-4669-8cc7-36746a06fb62--R00.html https://reports.osluv.org/static/assay/aerolamp%20devkit--27...
- Retz4o4 10mo ago
  OSLUV is fantastic; doing great work.
Bad_Initialism 10mo ago
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.
- briandw 10mo ago
  I need to get one :)
- philipkglass 10mo ago
  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.
- ansgri 10mo ago
  Do you have a recommendation for an inexpensive one? I’ve worked with OceanOptics Flame series, but they’re not exactly cheap, and their software was crap.

Animats 10mo ago

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-light https://cybernightmarket.com/products/nukit-lantern-far-uvc-...

Retz4o4 10mo ago
Not the same (less safe)
- Nukit 10mo ago
  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.
  - Retz4o4 10mo ago
    Sorry I will correct my post. I agree with you. Far UVC super safe
- vbelenky 10mo ago
  The spectra are slightly different, but Nukit is also filtered, I would expect it to be just as safe--just lower output
- Retz4o4 10mo ago
  To correct. Far UVC is super safe ;)

ralphonzathew 10mo ago

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.

vbelenky 10mo ago
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/10.1080/10643389.2022.2084315#d1e987 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/ 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!*

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tehjoker 10mo ago

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.

vbelenky 10mo ago
I don't really think 222nm UVC LEDs are going to be super relevant anytime soon https://www.convergentresearch.org/resources/convergent/solid-state-far-uvc-roadmapping-workshop-report 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.
- tehjoker 10mo ago
  I hadn't heard about the SHG platform. Thanks for the link!

nippoo 10mo ago

This isn't (entirely) new. I did the electronics design for this lamp: https://www.fridotechnologies.com 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.

Nukit 10mo ago

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-source/ 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.

jefftk 10mo ago
(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 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?
- Nukit 10mo ago
  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.

dskhatri 10mo ago

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.

vbelenky 10mo ago
Yeah, what responsibly deployed far-UV is definitely not is an instant kill beam that immediately inactivates exhaled pathogens. I estimate it takes 100 mW of far-UV about 5 minutes to inactivate 90% of the flu/covid in a 250 sqft room (10 minutes to get to 99%), assuming the air is well-mixed. Far-UV should be thought of as a super-powerful quiet air filter more than anything else--it prevents infectious aerosols from building up in a space, which can matter a lot. You don't necessarily immediately get infected just because someone infected coughed near you--you might only get infected if you spend a long time near them, sharing their air. Continuously cleaning the air prevents these kinds of infections, and can make the infections that do still happen less severe. You're totally right that circulating the air is important though! Definitely don't use far-UV in totally still air. But you don't necessarily need a LOT of air movement to achieve "good" mixing. Often just an air-change or so of ventilation is enough--just think about what would happen if you started smoking indoors. The smoke would be ~everywhere pretty fast. The oxygen absorption at 222nm is not significant however--it's enough to produce a bit of ozone (less than you'd get from just opening a window), but not enough to actually absorb a significant amount of radiation. 222nm lamps are generally less powerful than 254nm lamps anyway, but because 254nm is much less safe, those systems have to be deployed in ways that often reduce their efficacy--in special louvred fixtures that kill most of their output or in portable units/ducts that constrain their effectiveness. 222nm seems to be more effective per-photon at inactivating viruses than 254nm too: https://pubs.acs.org/doi/10.1021/acs.est.3c08675 https://pubs.acs.org/doi/10.1021/acs.est.3c08675

tetromino_ 10mo ago

Before buying something like this for my home, I'd need to know: * Is it safe for babies and small children (whose thin skin and developing eyes might well be much more vulnerable to UVC) * Is it actually safe for all adults regardless of skin type, colors, dermatologic conditions, or was it only tested on a few healthy college students of one particular ethnicity; * Does it accelerate degradation of household items, plastics, fabrics, books, and paint; and if so, by how much