[HN Gopher] You Can Just Buy Far-UVC
___________________________________________________________________
You Can Just Buy Far-UVC
Author : surprisetalk
Score : 50 points
Date : 2026-01-10 18:26 UTC (4 days ago)
(HTM) web link (www.jefftk.com)
(TXT) w3m dump (www.jefftk.com)
| joezydeco wrote:
| Leaving UVC sources exposed to eyesight is completely
| irresponsible. Please don't do this.
| toomuchtodo wrote:
| _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
| roywiggins wrote:
| I think that blog post is mostly just an AI summary of one or
| more of those studies.
| toomuchtodo wrote:
| Noted, it was included for completeness after I had
| independently found the resources I enumerate.
| modeless wrote:
| 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 wrote:
| FYI, all three of the studies are funded by UV light
| manufacturers: Ushio Inc (first two, 100%), and LumenLabs
| (last one, partially).
| jefftk wrote:
| (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 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.
| the8472 wrote:
| 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.
| trashface wrote:
| 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)
| IAmBroom wrote:
| 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 wrote:
| https://pmc.ncbi.nlm.nih.gov/articles/PMC10087841/
| Retz4o4 wrote:
| 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/
| throawayonthe wrote:
| no way you're supposed to point it down, right?
| gs17 wrote:
| Aerolamp insists that it's supposed to be pointed directly at
| "where people will spend time in the room", including tilting
| it down.
| Retz4o4 wrote:
| Yes you are - at the air that may be contaminated.
| lbotos wrote:
| 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 wrote:
| 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 wrote:
| 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)
| elil17 wrote:
| I do not believe that there is a good understanding of the
| impact of far-uvc on plastic embrittlement.
| toomuchtodo wrote:
| Delightful, an experiment to be run!
| TeMPOraL wrote:
| There's research to be done
|
| On the people who are
|
| Still alive.
| JoshTriplett wrote:
| 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.
| elil17 wrote:
| If you were going to duct it then why wouldn't you just use
| regular UVC? Much cheaper.
| JoshTriplett wrote:
| Fair point.
| gpm wrote:
| 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.
| mapontosevenths wrote:
| 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.
| juancn wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| I think that is the same thing as saying that Far UVC is
| non-carcinogenic.
| gpm wrote:
| 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.
| selfsimilar wrote:
| 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.
| wffurr wrote:
| >> 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...
| Retz4o4 wrote:
| Not the same wavelength as UV. This wavelength is blocked by
| your skin - and outer layer of your eyeballs!
| elil17 wrote:
| 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
| amelius wrote:
| > 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.
| gpm wrote:
| 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 wrote:
| 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.
| car wrote:
| 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...
| Modified3019 wrote:
| 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.
| n8cpdx wrote:
| 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 wrote:
| 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.
| HSO wrote:
| 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.
| PaulKeeble wrote:
| 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.
| jefftk wrote:
| 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
| tehjoker wrote:
| Yes, it's due to changing the pH of water in the air.
| parl_match wrote:
| > 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.
| bsder wrote:
| > 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.
| nmaleki wrote:
| You can buy UVC LEDs (255nm) for fairly cheap now. $20 or less
| briandw wrote:
| This is Far-UVC (typically 222 nm). Regular UVC can cause eye
| damage.
| jefftk wrote:
| And skin damage
| car wrote:
| Evolution has us covered.
|
| https://pmc.ncbi.nlm.nih.gov/articles/PMC3010660/
| miduil wrote:
| Yes, however the safety-profile is quite the opposite to 222nm.
|
| https://www.larsonelectronics.com/news/1763
|
| https://uvmedico.com/far-uvc-light
| car wrote:
| Do you know a good source for finding the latest, most
| efficient LEDs for DIY projects?
| car wrote:
| 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
| rdlecler1 wrote:
| 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.
|
| https://uviquity.com/
| car wrote:
| 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?
| api wrote:
| > 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 wrote:
| 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 wrote:
| (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...
| Retz4o4 wrote:
| OSLUV is fantastic; doing great work.
| Bad_Initialism wrote:
| 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 wrote:
| I need to get one :)
| philipkglass wrote:
| Does yours measure wavelengths that short? A lot of low cost
| spectrometers don't, because inexpensive glass and plastics
| optics transmit visible and near-IR radiation but
| significantly impair shorter UV wavelengths.
| Animats wrote:
| 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-...
| ralphonzathew wrote:
| 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.
| tehjoker wrote:
| 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.
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(page generated 2026-01-14 23:00 UTC)