13 ms·

Disinfection with Far-UV (222 nm Ultraviolet light) (2020) [pdf]

133 points by deegles 4y ago

jbm 4y ago
The Canadian government has a page that includes some information about the effects of Far-UV light against Covid-19. https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection/canadas-reponse/summaries-recent-evidence/ultraviolet-germicidal-irradiation-technologies-use-against-sars-cov-2.html#t1 https://www.canada.ca/en/public-health/services/diseases/201... > A whole room UV simulation demonstrated a far UV-C lamp (207-222 nm) could further reduce SARS-CoV-2 by 50-85% compared to ventilation alone and with both far UV-C and high ventilation the SARS-CoV-2 viral count was reduced by 90% in 6 minutes and 99% in 11.5 minutes Footnote 5. I wonder if this is something that I could add to my pre-existing home ventilation system; no concerns at all about skin exposure (which doesn't seem to be an actual issue based on this Boeing paper), and it shouldn't be so hard. * I found this (https://faruv.com/ https://faruv.com/) but I don't know how reliable they are. That said, if this really was that effective, I don't understand how viruses and bacteria are able to survive outside with our fusion-powered UV ray generator in the sky. -edit- * I feel dumb, here it is at the end of the summary. Looks like Boeing is working w/ faruv. > Boeing recently entered into patent and technology licenses with Healthe® Inc. and FarUV Technologies. Under these licenses, both companies will produce and distribute a commercial Far-UV 222 nm mobile wand, helping airlines and potentially others reduce the impact of the coronavirus pandemic.
- ericbarrett 4y ago
  UV-C is absorbed by the ozone layer.
- hedgehog 4y ago
  There are a few different ways I've read about far UV being deployed, one of the interesting ones is illuminating the upper few feet of a room. Exhaled breath tends to rise so apparently doing just the top of the room is more effective than you might expect. I hope this pans out to be effective, it would be a way to improve air quality without adding more noise to the space. Edit: The article's claim is that because far UV is absorbed in the upper atmosphere there's not really any evolutionary pressure for organisms to develop protection. Larger organisms just happen to be protected by virtue of our size.
- purpleblue 4y ago
  The wand will be useless unless they hold it above the area for 30+ seconds, which probably won't happen. Or unless the light is extremely intense which sounds dangerous.
  - lightedman 4y ago
    I tested this at work. 222nm, 265nm, 275nm, 290nm. Petri dishes colonized with human underarm flora were prepared, closed, then incubated for an hour at 80F. tested times were 30 seconds, 60 seconds, 2 minutes, 3 minutes, 5 minutes. 222nm doesn't take even 30 seconds to wipe things out. Every dish was totally clean. 265nm needed about 2 minutes to sterilize. 275nm almost got the job done at 3 minutes and had the 5 minute dish totally clean. 290nm was frankly pathetic. All of the dishes survived with barely-decreasing colony count across increasing times. I estimate it'd take an hour of exposure to clean the dish.
- com2kid 4y ago
  > That said, if this really was that effective, I don't understand how viruses and bacteria are able to survive outside with our fusion-powered UV ray generator in the sky. There is a reason that even during the height of the pandemic, that outdoor events were not a large source of transmission. People going into bars or houses after marching/protesting/partying were a problem, but standing around in the sunshine, even in a reasonably dense crowd, wasn't ever really a problem. (AFAIK, I remember news articles going "well that didn't turn out as bad as we all thought it would")
  - Krssst 4y ago
    If this was the reason, wouldn't it mean that we should be careful outside during the night?
- samstave 4y ago
  Wouldnt it be best to create a modular off-the-shelf instalable, positive pressure man-trap (extendable to walkable tunnel length, in the entrances to large public areas (stadiums, airports, trains, malls, etc) turn that wand into wall panels and let people walk through it - just like any other clean-room-style man-trap? https://i.imgur.com/8dMGNjN.gif https://i.imgur.com/8dMGNjN.gif
Maursault 4y ago
> recently published studies have demonstrated that UV light at 222nm has the same germicidal capabilities of 254nm light without damaging skin or eyes. 222nm may have the same capabilities, but not the same efficacy and efficiency as 254nm (or 185nm, the germicidal action if which is it creates ozone, which does the disinefecting). Still, if it works but just takes longer without the sunburn and blindness, whether by proximity to 254nm such that some 254nm is still present, and/or by proximity to 185nm such that ozone is still created, well, ok.
- hedgehog 4y ago
  According to the linked article: "While the effects on live tissue are diminished, Far-UV (222 nm light being the most prevalent) has increased efficacy for killing bacteria and viruses."
  - Maursault 4y ago
    That's misleading, increased efficacy as opposed to what? A control? It's not more than 254nm, which has been long proven, in repeated studies, to be the most efficient germicidal wavelength, decreasing in near wavelengths depending on how close they are to 254nm. 222nm is only 32nm of wavelength difference to 254nm, and I'll wager that even 238nm is more efficient than 222nm, but maybe 238nm burns skin. 222nm is nearly half way between 185nm and 254nm, so it will have some of the germicidal effects of both wavelengths, but it won't be more than either 185nm or 254nm. But it may be enough, and if it doesn't hurt people, then kudoes.
    - scythe 4y ago
      >254 nm ... which just happens to be exactly the second spectral line of a low-pressure mercury-vapor lamp. Actually 253.7. The other line is 184.5. Are you sure that the study you read isn't just reporting this wavelength as ideal because we have a convenient source of it? Efficient far-UV sources tend to be few and far between. It would be an awfully big coincidence if the two major spectral lines of an Hg plasma just happen to be the two ideal wavelengths for disinfection. FWIW, zinc vapor has a persistent line at 214 nm, but I've never heard of this being applied in a commercial bulb. Other relevant possibilities are all toxic.
blairanderson 4y ago
I recently visited a national trade show for HVACR folks and found this company: https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ Thought it might be applicable to computers, but realized that UV breaks-down PLASTICS as well, which is why you mostly find in ducting. Very cool stuff if you're into clean/sterile living. Note: Most of the dust in your home is comprised of human skin. Unless you've had an industrial vacuuming, other people's skin is moving around your house or gumming up the walls of your ducts. UV lights (and chemicals) are the only way to break that shit down.
- wnevets 4y ago
  Wouldn't UV-light in ducting generate ozone? Even relatively small amounts of ozone can be harmful. > When inhaled, ozone can damage the lungs. Relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation. [0] [0] https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners#harmful-ozone https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-...
  - RetpolineDrama 4y ago
    Carrier at least claims their UV upgrade does not produce ozone. Not sure how accurate that is though.
  - Eisenstein 4y ago
    Ozone is produced at 185nm. Standard germicidal UV-C lights are ~250nm. The issue is that some germicidal bulbs do not filter out the lower wavelengths and thus produce ozone (sometimes on purpose since ozone is also germicidal). See [0]. [0] https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation#Lamps https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradia...
    - wnevets 4y ago
      >Ozone is produced at 185nm Where did you find that 185nm number? Everything I see on google says ~250nm, not to mention the original post is about 222nm UV.
EGreg 4y ago
Hi everyone. I had this idea two years ago, and made an entire website and video about it: https://uvspinner.com/ https://uvspinner.com/ Tried to get the NYC mayor's office interested, but they just pawned me off to a black hole of submitting forms that no one reads. If anyone still wants to do it, shoot me an email, username is greg with the domain "qbix.com" or add me on Facebook
purpleblue 4y ago
At the beginning of the pandemic, I read about UVC light and purchased a UVC light bulb before they ran out online. I used it to sterilize my N95 masks which were impossible to find, and all the research I did showed that you could do this 20+ times without affecting air flow or filtration of the mask. I even found studies that talked about how to use it to disinfect flu virus so I used those as a guideline as to how long I should expose the masks. I even went so far as to buy ajar and tested that the UVC light at least killed bacteria as advertised. I know viruses are much tinier and there's no way to test for the virus but at least I knew it was working as advertised for bacteria. Of course all this ended up being useless, but it was a fun project during the pandemic.
- smileysteve 4y ago
  similar, i read something about uv-c in 2019; and also how washing machines most active cleaning is from water (they don't kill things well), so had added a uv-c light to "treat" my laundry.
  - mr_toad 4y ago
    The water and soap remove dirt and grease that bacteria feeds on and lives in. You don’t need to sterilise your clothes, you just need to stop them being a breeding ground.
maximilianburke 4y ago
One of the most driven* and intelligent people I have ever had the opportunity to work with (Saimir Sulaj) left my company to found a startup that's building far UV disinfection devices: https://www.uvxinc.com/ https://www.uvxinc.com/ *I mean, it requires a certain kind of stubborn determination to do a hardware startup, and I hope he's crushing it.
- com2kid 4y ago
  Unfortunate it is one of those "inquire now" things, if there was a "buy now" link I'd pick a few up right away.
  - sethikunal 4y ago
    [dead]
joezydeco 4y ago
UV will break down a lot of plastics, especially if stabilizers are not added. I'm curious why the study didn't mention this at all. How long can that bathroom hold out?
- jefftk 4y ago
  If you're Boeing considering building it into planes it seems like you're in a great position for choosing UV-compatible materials. (Compared to the more normal situation of someone retrofitting an office, bar, or other normal space with 222-nm lighting.)
RenThraysk 4y ago
It's a shame we haven't figured out to make efficient Far-UV leds. The performance drops off a cliff once start to get below 265nm (IIRC)
- lightedman 4y ago
  The performance drops off a cliff to tungsten-lamp levels starting in the UVB (290-310nm) range. We're still looking at state of the art at barely 3% efficiency for that and UVC.
apienx 4y ago
This group's notorious for shining UV at fashionable pathogens. https://www.nature.com/articles/s41598-020-67211-2 https://www.nature.com/articles/s41598-020-67211-2
donsupreme 4y ago
I am curious if the ambience air can be too "sterile", that we will come to find out there are some good microbes in the air that is beneficial to our health.
- qbasic_forever 4y ago
  Our body would have evolved to keep whatever these 'good' microbes are in and near our lungs, much like it does for our intestines and digestive system. The lack of this system, and the evolution of things like hair and mucous in our nose to filter and trap foreign objects is a pretty good hint that our body doesn't want anything except our clean atmosphere in our lungs.
  - malfist 4y ago
    Fair, but your body also does away with things it's not using. An inactive immune system for too sterile environments may result in not being able to protect yourself in less sterile environments, or the immune system finding uses for itself, i.e. an autoimmune disease like allergies.
    - qbasic_forever 4y ago
      The immune system is not a muscle--you don't need to keep exposing yourself to pathogens. Think how ridiculous that sounds--are you going to go get rabies, ebola, HIV, brain eating bacteria, etc. to be 'healthy'?
      - mr_toad 4y ago
        The whole point of a vaccine is to expose the immune system to an antigen.
        qbasic_forever 4y ago
        No, you're exposing a harmless or safe part of an antigen to stimulate memory B and T cell immune response in the future. Rawdogging unfiltered air with true COVID or other bad virons will expose you to a potentially harmful virus--millions of people have been killed and many more disabled from it so far. You have no way of knowing if you will join their fate and are just rolling the dice.
jefftk 4y ago
Dereck Lowe ("In the Pipeline") has a good article on germicidal 222-nm: https://www.science.org/content/blog-post/two-twenty-two https://www.science.org/content/blog-post/two-twenty-two
londons_explore 4y ago
We need more studies, or maybe metastudies, that compare the germicidal benefits of UV lamps with the health disadvantages (skin cancer, ozone). It seems that there is consensus on both effects, but I can't find anything conclusive that allows the scale of the effects to be measured sufficiently to do a benefit/cost analysis for each type of light spectrum and usecase.
- lazide 4y ago
  Skin cancer is easy to prevent by not allowing the light to shine directly on anyones skin, and using non-UV reflective enclosures. Ozone is already a known and easily tested quantity, and generally only happens at 240nm and lower wavelengths. So 222 as listed might produce some, but doesn't seem optimal (180nm seems better). Found a paper - seems likely that is the case [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391] Note scale on the first graph. edit: ah hah, but many of these lamps have defects that can result in higher freq. light emission and high ozone production! See later parts of the paper.
- deleted 4y ago
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- modestmc 4y ago
  Far-UVC (~205-222 nm) light can’t penetrate cell walls and thus does not risk DNA damage. However, our skin heavily depends on friendly bacteria to do useful things. One concern that I have yet to see research testing is the impact of extended Far-UVC exposure on these microbial populations.
  - thfuran 4y ago
    Human cells don't have cell walls.
    - modestmc 4y ago
      My apologies, the membrane. I went and dug more into this to brush up on the exact specifics and the exact conclusion of the research was that less than 5% of the intensity of the light reached the nuclear envelope, thus avoiding DNA damage. This is the original study: https://ieeexplore.ieee.org/abstract/document/1341520/ https://ieeexplore.ieee.org/abstract/document/1341520/ However, while I was trying to find the specifics on the DNA damage, I found this: https://mdpi-res.com/d_attachment/ijms/ijms-23-09112/article_deploy/ijms-23-09112.pdf https://mdpi-res.com/d_attachment/ijms/ijms-23-09112/article... My only grief with this article is the conclusion they draw from the yH2AX staining. I can see several possible reasons for observing the higher proportion of cells with it. Other than that, the paper raises a boatload of serious points and definitely observes negatively impacted cellular function. I still think FarUVC has incredible potential but just like cellphone towers the exact specifics to interact with it safely need serious further study.
bilsbie 4y ago
Remember when we needed germs to exercise our immune systems? Remember immune systems?
- deegles 4y ago
  let me know how your exercise with avian flu, yellow fever, HIV, ebola, hepatitis, etc etc etc goes.
  - guntherhermann 4y ago
    1) Cool it with the snark 2) Ebola, Yellow Fever, HIV & Hepatitis aren't airborne, so probably wouldn't be the kind of viruses that the parent is talking about
    - deegles 4y ago
      They'll just have to chime in and clarify which pathogens they meant. I was snarky because the idea of "exercising the immune system" is misinformation and used by "immunity debt" proponents.
- 2muchcoffeeman 4y ago
  I think there is a big difference between exercising your immune system and creating a Petri dish for air borne diseases. If COVID has taught us anything, it’s that ventilation in many buildings sucks big time. We need to either improve ventilation, or start killing viruses. I mean, if you’re going to go the naturalistic angle, then what’s natural about squashing people into buildings with poor air flow?
  - ChrisMarshallNY 4y ago
    > ventilation in many buildings sucks We've known that for a long time[0]. I have friends that are plumbers and HVAC people, that have to do strange stuff, by law. [0] https://www.cdc.gov/legionella/index.html https://www.cdc.gov/legionella/index.html
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modestmc 4y ago
Nice to see this on HN, this is a big deal. I did research in 2021 to generate Far-UVC using nonlinear plasmonics. The holy grail for this technology is a Far-UVC Diode. The guy who won the Nobel Prize for the blue LED (IIRC) is working with other physicists at UCSB to try and create said diode: https://www.news.ucsb.edu/2020/019949/uv-lights-way https://www.news.ucsb.edu/2020/019949/uv-lights-way If you want to learn more about Far-UVC itself (safety, etc), David Brenner is the real MVP: http://www.columbia.edu/~djb3/ http://www.columbia.edu/~djb3/
- Animats 4y ago
  > The holy grail for this technology is a Far-UVC Diode. Right. Currently, 222nm lamps are gas-discharge tubes, and they cost far too much. There are fake 222nm LED lamps available online. There are also units that produce what Naomi Wu calls "homeopathic levels" of UV. Beware of scams. If this is to go anywhere, a low-cost tester is needed. You can get a hand held UV spectrograph for about $3000, but that's more of a lab instrument. Something like a detector on a stick that lights up green for enough 222nm UV to be useful, and red for too much UV in dangerous parts of the spectrum. One idea is to have a unit up near the ceiling that emits UV in a horizontal plane, so that air that makes it up to the ceiling gets sterilized. Convection, maybe with ceiling fan help, can move air through that region. But humans aren't up near the ceiling much, so they don't look into a UV source.
  - galangalalgol 4y ago
    This still seems kinda scary. The scatter off the walls seems like it would be a problem for eyes or even skin over time. Would it generate ozone? What are the by-products of ionizing dust and what happens when you breath them?
    - MengerSponge 4y ago
      The good thing about far uvc is it isn't penetrating. It doesn't it make it through your your outermost cornea or epidermis layers. Scatter is also negligible as long as its set up competently: reflectivity is very different for UV and visible light. Ozone production certainly limits the maximum power that can be used, but as I understand it you don't need to crank anything close to max power to attenuate the airborne viral load.
lstodd 4y ago
Disinfection is harmful unless absolutely needed. Same as overuse of antibiotics - it only breeds more resistant strains and harms the immune systems because of lack of less resistant strains.
- blacksmith_tb 4y ago
  Potentially - though it's a lot harder to evolve resistance to physical destruction than it is to a given antibiotic. The other aspect, aka 'the hygiene hypothesis' still holds, killing more pathogens may well lead to weakened immune response from lack of exposure.
  - deegles 4y ago
    The immune system is not a muscle that needs to be "exercised."
    - lstodd 4y ago
      By that logic vaccines can't work
      - deegles 4y ago
        Read this: https://www.mcgill.ca/oss/article/critical-thinking-health-general-science/boost-your-knowledge-about-boosting-your-immune-system https://www.mcgill.ca/oss/article/critical-thinking-health-g...
    - wkat4242 4y ago
      But it can be trained to recognize diseases at low dosages so it becomes more responsive when you have direct contact with a carrier
- msandford 4y ago
  Germs don't get a chance to evolve resistance to this, at least as far as I can tell. At least not any more than humans have the opportunity to evolve a bullet defense. The UVC doesn't disrupt their metabolism or mutate their genetics subtly, it shreds their chemical bonds. It's much more like worrying that germs will evolve resistance to hydrogen peroxide or ethanol or iodine disinfectants. It's not impossible of course, but it'll require the kinds of mutations that make them entirely other organisms.
beambot 4y ago
As a safety & security robotics company, we looked at UVC applications early during the pandemic. We came to the same conclusions as Avidbots, which they published online: https://avidbots.com/resources/what-you-need-to-know-about-uvc-lights-and-autonomous-floor-scrubbing-robots/ https://avidbots.com/resources/what-you-need-to-know-about-u... TLDR: The level of light insolation you need for disinfection makes them less useful for large area coverage and/or areas exposed to the public due to eye safety concerns.
- ajmurmann 4y ago
  Note that this is about far UVC light. There were recent studies that showed that it's safe for humans and multi-celled organisms. The absorption by cells is so effective that the radiation is entirely absorpted by the top cell layer.
aaron695 4y ago
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Plough_Jogger 4y ago
The team at R-Zero Systems has a Far-UV product on the market: https://rzero.com/vive/ https://rzero.com/vive/
refurb 4y ago
https://www.biorxiv.org/content/10.1101/2022.02.22.481471v1.full https://www.biorxiv.org/content/10.1101/2022.02.22.481471v1.... However, cells exposed to 222-nm far UVC presented the highest degree of DNA damage as evidenced by yH2AX staining. Globally, these cells presented transcriptional changes in cell cycle and senescence pathways. Thus, the introduction of 222-nm far UVC lamps for disinfection purposes should be carefully considered and designed with the inherent dangers involved.
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ajmurmann 4y ago
I learned about this not long after it came out. That this didn't see a big push my the government during the pandemic and that practically nothing has been spent on ventilation to me are some of the most confidence shaking aspects of how the pandemic was handled
scotty79 4y ago
I think it's already used in some places: https://www.reddit.com/r/ZeroCovidCommunity/comments/10kbkhz/are_the_far_uvc_units_at_davos_commercially/ https://www.reddit.com/r/ZeroCovidCommunity/comments/10kbkhz...
nikolay 4y ago
I've been researching this and it's too bad that only a few companies produce these, and the pricing is outrageous! I understand they want to make sure only 222nm UVC is produced, but still, come on!

133 points by deegles 4y ago

jbm 4y ago

The Canadian government has a page that includes some information about the effects of Far-UV light against Covid-19. https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection/canadas-reponse/summaries-recent-evidence/ultraviolet-germicidal-irradiation-technologies-use-against-sars-cov-2.html#t1 https://www.canada.ca/en/public-health/services/diseases/201... > A whole room UV simulation demonstrated a far UV-C lamp (207-222 nm) could further reduce SARS-CoV-2 by 50-85% compared to ventilation alone and with both far UV-C and high ventilation the SARS-CoV-2 viral count was reduced by 90% in 6 minutes and 99% in 11.5 minutes Footnote 5. I wonder if this is something that I could add to my pre-existing home ventilation system; no concerns at all about skin exposure (which doesn't seem to be an actual issue based on this Boeing paper), and it shouldn't be so hard. * I found this (https://faruv.com/ https://faruv.com/) but I don't know how reliable they are. That said, if this really was that effective, I don't understand how viruses and bacteria are able to survive outside with our fusion-powered UV ray generator in the sky. -edit- * I feel dumb, here it is at the end of the summary. Looks like Boeing is working w/ faruv. > Boeing recently entered into patent and technology licenses with Healthe® Inc. and FarUV Technologies. Under these licenses, both companies will produce and distribute a commercial Far-UV 222 nm mobile wand, helping airlines and potentially others reduce the impact of the coronavirus pandemic.

ericbarrett 4y ago
UV-C is absorbed by the ozone layer.
hedgehog 4y ago
There are a few different ways I've read about far UV being deployed, one of the interesting ones is illuminating the upper few feet of a room. Exhaled breath tends to rise so apparently doing just the top of the room is more effective than you might expect. I hope this pans out to be effective, it would be a way to improve air quality without adding more noise to the space. Edit: The article's claim is that because far UV is absorbed in the upper atmosphere there's not really any evolutionary pressure for organisms to develop protection. Larger organisms just happen to be protected by virtue of our size.
purpleblue 4y ago
The wand will be useless unless they hold it above the area for 30+ seconds, which probably won't happen. Or unless the light is extremely intense which sounds dangerous.
- lightedman 4y ago
  I tested this at work. 222nm, 265nm, 275nm, 290nm. Petri dishes colonized with human underarm flora were prepared, closed, then incubated for an hour at 80F. tested times were 30 seconds, 60 seconds, 2 minutes, 3 minutes, 5 minutes. 222nm doesn't take even 30 seconds to wipe things out. Every dish was totally clean. 265nm needed about 2 minutes to sterilize. 275nm almost got the job done at 3 minutes and had the 5 minute dish totally clean. 290nm was frankly pathetic. All of the dishes survived with barely-decreasing colony count across increasing times. I estimate it'd take an hour of exposure to clean the dish.
com2kid 4y ago
> That said, if this really was that effective, I don't understand how viruses and bacteria are able to survive outside with our fusion-powered UV ray generator in the sky. There is a reason that even during the height of the pandemic, that outdoor events were not a large source of transmission. People going into bars or houses after marching/protesting/partying were a problem, but standing around in the sunshine, even in a reasonably dense crowd, wasn't ever really a problem. (AFAIK, I remember news articles going "well that didn't turn out as bad as we all thought it would")
- Krssst 4y ago
  If this was the reason, wouldn't it mean that we should be careful outside during the night?
samstave 4y ago
Wouldnt it be best to create a modular off-the-shelf instalable, positive pressure man-trap (extendable to walkable tunnel length, in the entrances to large public areas (stadiums, airports, trains, malls, etc) turn that wand into wall panels and let people walk through it - just like any other clean-room-style man-trap? https://i.imgur.com/8dMGNjN.gif https://i.imgur.com/8dMGNjN.gif

Maursault 4y ago

> recently published studies have demonstrated that UV light at 222nm has the same germicidal capabilities of 254nm light without damaging skin or eyes. 222nm may have the same capabilities, but not the same efficacy and efficiency as 254nm (or 185nm, the germicidal action if which is it creates ozone, which does the disinefecting). Still, if it works but just takes longer without the sunburn and blindness, whether by proximity to 254nm such that some 254nm is still present, and/or by proximity to 185nm such that ozone is still created, well, ok.

hedgehog 4y ago
According to the linked article: "While the effects on live tissue are diminished, Far-UV (222 nm light being the most prevalent) has increased efficacy for killing bacteria and viruses."
- Maursault 4y ago
  That's misleading, increased efficacy as opposed to what? A control? It's not more than 254nm, which has been long proven, in repeated studies, to be the most efficient germicidal wavelength, decreasing in near wavelengths depending on how close they are to 254nm. 222nm is only 32nm of wavelength difference to 254nm, and I'll wager that even 238nm is more efficient than 222nm, but maybe 238nm burns skin. 222nm is nearly half way between 185nm and 254nm, so it will have some of the germicidal effects of both wavelengths, but it won't be more than either 185nm or 254nm. But it may be enough, and if it doesn't hurt people, then kudoes.
  - scythe 4y ago
    >254 nm ... which just happens to be exactly the second spectral line of a low-pressure mercury-vapor lamp. Actually 253.7. The other line is 184.5. Are you sure that the study you read isn't just reporting this wavelength as ideal because we have a convenient source of it? Efficient far-UV sources tend to be few and far between. It would be an awfully big coincidence if the two major spectral lines of an Hg plasma just happen to be the two ideal wavelengths for disinfection. FWIW, zinc vapor has a persistent line at 214 nm, but I've never heard of this being applied in a commercial bulb. Other relevant possibilities are all toxic.

blairanderson 4y ago

I recently visited a national trade show for HVACR folks and found this company: https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ Thought it might be applicable to computers, but realized that UV breaks-down PLASTICS as well, which is why you mostly find in ducting. Very cool stuff if you're into clean/sterile living. Note: Most of the dust in your home is comprised of human skin. Unless you've had an industrial vacuuming, other people's skin is moving around your house or gumming up the walls of your ducts. UV lights (and chemicals) are the only way to break that shit down.

wnevets 4y ago
Wouldn't UV-light in ducting generate ozone? Even relatively small amounts of ozone can be harmful. > When inhaled, ozone can damage the lungs. Relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation. [0] [0] https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners#harmful-ozone https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-...
- RetpolineDrama 4y ago
  Carrier at least claims their UV upgrade does not produce ozone. Not sure how accurate that is though.
- Eisenstein 4y ago
  Ozone is produced at 185nm. Standard germicidal UV-C lights are ~250nm. The issue is that some germicidal bulbs do not filter out the lower wavelengths and thus produce ozone (sometimes on purpose since ozone is also germicidal). See [0]. [0] https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation#Lamps https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradia...
  - wnevets 4y ago
    >Ozone is produced at 185nm Where did you find that 185nm number? Everything I see on google says ~250nm, not to mention the original post is about 222nm UV.

EGreg 4y ago

Hi everyone. I had this idea two years ago, and made an entire website and video about it: https://uvspinner.com/ https://uvspinner.com/ Tried to get the NYC mayor's office interested, but they just pawned me off to a black hole of submitting forms that no one reads. If anyone still wants to do it, shoot me an email, username is greg with the domain "qbix.com" or add me on Facebook

purpleblue 4y ago

At the beginning of the pandemic, I read about UVC light and purchased a UVC light bulb before they ran out online. I used it to sterilize my N95 masks which were impossible to find, and all the research I did showed that you could do this 20+ times without affecting air flow or filtration of the mask. I even found studies that talked about how to use it to disinfect flu virus so I used those as a guideline as to how long I should expose the masks. I even went so far as to buy ajar and tested that the UVC light at least killed bacteria as advertised. I know viruses are much tinier and there's no way to test for the virus but at least I knew it was working as advertised for bacteria. Of course all this ended up being useless, but it was a fun project during the pandemic.

smileysteve 4y ago
similar, i read something about uv-c in 2019; and also how washing machines most active cleaning is from water (they don't kill things well), so had added a uv-c light to "treat" my laundry.
- mr_toad 4y ago
  The water and soap remove dirt and grease that bacteria feeds on and lives in. You don’t need to sterilise your clothes, you just need to stop them being a breeding ground.

maximilianburke 4y ago

One of the most driven* and intelligent people I have ever had the opportunity to work with (Saimir Sulaj) left my company to found a startup that's building far UV disinfection devices: https://www.uvxinc.com/ https://www.uvxinc.com/ *I mean, it requires a certain kind of stubborn determination to do a hardware startup, and I hope he's crushing it.

com2kid 4y ago
Unfortunate it is one of those "inquire now" things, if there was a "buy now" link I'd pick a few up right away.
- sethikunal 4y ago
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joezydeco 4y ago

UV will break down a lot of plastics, especially if stabilizers are not added. I'm curious why the study didn't mention this at all. How long can that bathroom hold out?

jefftk 4y ago
If you're Boeing considering building it into planes it seems like you're in a great position for choosing UV-compatible materials. (Compared to the more normal situation of someone retrofitting an office, bar, or other normal space with 222-nm lighting.)

RenThraysk 4y ago

It's a shame we haven't figured out to make efficient Far-UV leds. The performance drops off a cliff once start to get below 265nm (IIRC)

lightedman 4y ago
The performance drops off a cliff to tungsten-lamp levels starting in the UVB (290-310nm) range. We're still looking at state of the art at barely 3% efficiency for that and UVC.

apienx 4y ago

This group's notorious for shining UV at fashionable pathogens. https://www.nature.com/articles/s41598-020-67211-2 https://www.nature.com/articles/s41598-020-67211-2

donsupreme 4y ago

I am curious if the ambience air can be too "sterile", that we will come to find out there are some good microbes in the air that is beneficial to our health.

qbasic_forever 4y ago
Our body would have evolved to keep whatever these 'good' microbes are in and near our lungs, much like it does for our intestines and digestive system. The lack of this system, and the evolution of things like hair and mucous in our nose to filter and trap foreign objects is a pretty good hint that our body doesn't want anything except our clean atmosphere in our lungs.
- malfist 4y ago
  Fair, but your body also does away with things it's not using. An inactive immune system for too sterile environments may result in not being able to protect yourself in less sterile environments, or the immune system finding uses for itself, i.e. an autoimmune disease like allergies.
  - qbasic_forever 4y ago
    The immune system is not a muscle--you don't need to keep exposing yourself to pathogens. Think how ridiculous that sounds--are you going to go get rabies, ebola, HIV, brain eating bacteria, etc. to be 'healthy'?
    - mr_toad 4y ago
      The whole point of a vaccine is to expose the immune system to an antigen.
      - qbasic_forever 4y ago
        No, you're exposing a harmless or safe part of an antigen to stimulate memory B and T cell immune response in the future. Rawdogging unfiltered air with true COVID or other bad virons will expose you to a potentially harmful virus--millions of people have been killed and many more disabled from it so far. You have no way of knowing if you will join their fate and are just rolling the dice.

jefftk 4y ago

Dereck Lowe ("In the Pipeline") has a good article on germicidal 222-nm: https://www.science.org/content/blog-post/two-twenty-two https://www.science.org/content/blog-post/two-twenty-two

londons_explore 4y ago

We need more studies, or maybe metastudies, that compare the germicidal benefits of UV lamps with the health disadvantages (skin cancer, ozone). It seems that there is consensus on both effects, but I can't find anything conclusive that allows the scale of the effects to be measured sufficiently to do a benefit/cost analysis for each type of light spectrum and usecase.

lazide 4y ago
Skin cancer is easy to prevent by not allowing the light to shine directly on anyones skin, and using non-UV reflective enclosures. Ozone is already a known and easily tested quantity, and generally only happens at 240nm and lower wavelengths. So 222 as listed might produce some, but doesn't seem optimal (180nm seems better). Found a paper - seems likely that is the case [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391] Note scale on the first graph. edit: ah hah, but many of these lamps have defects that can result in higher freq. light emission and high ozone production! See later parts of the paper.
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modestmc 4y ago
Far-UVC (~205-222 nm) light can’t penetrate cell walls and thus does not risk DNA damage. However, our skin heavily depends on friendly bacteria to do useful things. One concern that I have yet to see research testing is the impact of extended Far-UVC exposure on these microbial populations.
- thfuran 4y ago
  Human cells don't have cell walls.
  - modestmc 4y ago
    My apologies, the membrane. I went and dug more into this to brush up on the exact specifics and the exact conclusion of the research was that less than 5% of the intensity of the light reached the nuclear envelope, thus avoiding DNA damage. This is the original study: https://ieeexplore.ieee.org/abstract/document/1341520/ https://ieeexplore.ieee.org/abstract/document/1341520/ However, while I was trying to find the specifics on the DNA damage, I found this: https://mdpi-res.com/d_attachment/ijms/ijms-23-09112/article_deploy/ijms-23-09112.pdf https://mdpi-res.com/d_attachment/ijms/ijms-23-09112/article... My only grief with this article is the conclusion they draw from the yH2AX staining. I can see several possible reasons for observing the higher proportion of cells with it. Other than that, the paper raises a boatload of serious points and definitely observes negatively impacted cellular function. I still think FarUVC has incredible potential but just like cellphone towers the exact specifics to interact with it safely need serious further study.

bilsbie 4y ago

Remember when we needed germs to exercise our immune systems? Remember immune systems?

deegles 4y ago
let me know how your exercise with avian flu, yellow fever, HIV, ebola, hepatitis, etc etc etc goes.
- guntherhermann 4y ago
  1) Cool it with the snark 2) Ebola, Yellow Fever, HIV & Hepatitis aren't airborne, so probably wouldn't be the kind of viruses that the parent is talking about
  - deegles 4y ago
    They'll just have to chime in and clarify which pathogens they meant. I was snarky because the idea of "exercising the immune system" is misinformation and used by "immunity debt" proponents.
2muchcoffeeman 4y ago
I think there is a big difference between exercising your immune system and creating a Petri dish for air borne diseases. If COVID has taught us anything, it’s that ventilation in many buildings sucks big time. We need to either improve ventilation, or start killing viruses. I mean, if you’re going to go the naturalistic angle, then what’s natural about squashing people into buildings with poor air flow?
- ChrisMarshallNY 4y ago
  > ventilation in many buildings sucks We've known that for a long time[0]. I have friends that are plumbers and HVAC people, that have to do strange stuff, by law. [0] https://www.cdc.gov/legionella/index.html https://www.cdc.gov/legionella/index.html

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modestmc 4y ago

Nice to see this on HN, this is a big deal. I did research in 2021 to generate Far-UVC using nonlinear plasmonics. The holy grail for this technology is a Far-UVC Diode. The guy who won the Nobel Prize for the blue LED (IIRC) is working with other physicists at UCSB to try and create said diode: https://www.news.ucsb.edu/2020/019949/uv-lights-way https://www.news.ucsb.edu/2020/019949/uv-lights-way If you want to learn more about Far-UVC itself (safety, etc), David Brenner is the real MVP: http://www.columbia.edu/~djb3/ http://www.columbia.edu/~djb3/

Animats 4y ago
> The holy grail for this technology is a Far-UVC Diode. Right. Currently, 222nm lamps are gas-discharge tubes, and they cost far too much. There are fake 222nm LED lamps available online. There are also units that produce what Naomi Wu calls "homeopathic levels" of UV. Beware of scams. If this is to go anywhere, a low-cost tester is needed. You can get a hand held UV spectrograph for about $3000, but that's more of a lab instrument. Something like a detector on a stick that lights up green for enough 222nm UV to be useful, and red for too much UV in dangerous parts of the spectrum. One idea is to have a unit up near the ceiling that emits UV in a horizontal plane, so that air that makes it up to the ceiling gets sterilized. Convection, maybe with ceiling fan help, can move air through that region. But humans aren't up near the ceiling much, so they don't look into a UV source.
- galangalalgol 4y ago
  This still seems kinda scary. The scatter off the walls seems like it would be a problem for eyes or even skin over time. Would it generate ozone? What are the by-products of ionizing dust and what happens when you breath them?
  - MengerSponge 4y ago
    The good thing about far uvc is it isn't penetrating. It doesn't it make it through your your outermost cornea or epidermis layers. Scatter is also negligible as long as its set up competently: reflectivity is very different for UV and visible light. Ozone production certainly limits the maximum power that can be used, but as I understand it you don't need to crank anything close to max power to attenuate the airborne viral load.

lstodd 4y ago

Disinfection is harmful unless absolutely needed. Same as overuse of antibiotics - it only breeds more resistant strains and harms the immune systems because of lack of less resistant strains.

blacksmith_tb 4y ago
Potentially - though it's a lot harder to evolve resistance to physical destruction than it is to a given antibiotic. The other aspect, aka 'the hygiene hypothesis' still holds, killing more pathogens may well lead to weakened immune response from lack of exposure.
- deegles 4y ago
  The immune system is not a muscle that needs to be "exercised."
  - lstodd 4y ago
    By that logic vaccines can't work
    - deegles 4y ago
      Read this: https://www.mcgill.ca/oss/article/critical-thinking-health-general-science/boost-your-knowledge-about-boosting-your-immune-system https://www.mcgill.ca/oss/article/critical-thinking-health-g...
  - wkat4242 4y ago
    But it can be trained to recognize diseases at low dosages so it becomes more responsive when you have direct contact with a carrier
msandford 4y ago
Germs don't get a chance to evolve resistance to this, at least as far as I can tell. At least not any more than humans have the opportunity to evolve a bullet defense. The UVC doesn't disrupt their metabolism or mutate their genetics subtly, it shreds their chemical bonds. It's much more like worrying that germs will evolve resistance to hydrogen peroxide or ethanol or iodine disinfectants. It's not impossible of course, but it'll require the kinds of mutations that make them entirely other organisms.

beambot 4y ago

As a safety & security robotics company, we looked at UVC applications early during the pandemic. We came to the same conclusions as Avidbots, which they published online: https://avidbots.com/resources/what-you-need-to-know-about-uvc-lights-and-autonomous-floor-scrubbing-robots/ https://avidbots.com/resources/what-you-need-to-know-about-u... TLDR: The level of light insolation you need for disinfection makes them less useful for large area coverage and/or areas exposed to the public due to eye safety concerns.

ajmurmann 4y ago
Note that this is about far UVC light. There were recent studies that showed that it's safe for humans and multi-celled organisms. The absorption by cells is so effective that the radiation is entirely absorpted by the top cell layer.

aaron695 4y ago

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Plough_Jogger 4y ago

The team at R-Zero Systems has a Far-UV product on the market: https://rzero.com/vive/ https://rzero.com/vive/

refurb 4y ago

https://www.biorxiv.org/content/10.1101/2022.02.22.481471v1.full https://www.biorxiv.org/content/10.1101/2022.02.22.481471v1.... However, cells exposed to 222-nm far UVC presented the highest degree of DNA damage as evidenced by yH2AX staining. Globally, these cells presented transcriptional changes in cell cycle and senescence pathways. Thus, the introduction of 222-nm far UVC lamps for disinfection purposes should be carefully considered and designed with the inherent dangers involved.

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ajmurmann 4y ago

I learned about this not long after it came out. That this didn't see a big push my the government during the pandemic and that practically nothing has been spent on ventilation to me are some of the most confidence shaking aspects of how the pandemic was handled

scotty79 4y ago

I think it's already used in some places: https://www.reddit.com/r/ZeroCovidCommunity/comments/10kbkhz/are_the_far_uvc_units_at_davos_commercially/ https://www.reddit.com/r/ZeroCovidCommunity/comments/10kbkhz...

nikolay 4y ago

I've been researching this and it's too bad that only a few companies produce these, and the pricing is outrageous! I understand they want to make sure only 222nm UVC is produced, but still, come on!