If you search my username in this thread, you'll see another comment by myself. I can't remember the product name, but there exists a company that makes a UV light system that swaps out for the usual fluorescent light you see in most commercial buildings. I'm not affiliated with the company at all.
This is really cool! At the start of the pandemic, I researched UVC light as a mechanism to kill the virus. I do want to point out a minor point:
>However, the widespread use of germicidal ultraviolet light in public settings has been very limited because conventional UVC light sources are a human health hazard, being both carcinogenic and cataractogenic
conventional UVC is generated by mercury light bulbs and are carcinogenic and cataractogenic
BUT about 10 years ago, it became practical to use frequency doubling in LEDs to generate light really close to the mercury light - the LEDs are not carcinogenic and cataractogenic. When you read about UVC effects, you should check what type of light source they are using (mercury vs LED)
Also, it is the advancements in silicon manufacturing that has made it cheaper to make new and different LEDs - such as these "far-UVCs". It is pretty legit!
There is "a lot" of research demonstrating effectiveness of "conventional UVC", but not a lot on "far-UVC". One of the limitations on both is the shadow effect... got to go. I'll elaborate if there is interest
Not the OP but the shadow effect is that the light can only kill viruses if it reaches them directly. So if the virus is on your skin under your clothes or in your nose or behind a sofa, the light can't reach it. If the virus is embedded in dirt or opaque oils the light can't reach it. If you're in a crowded room and there is a temporary display that was put up everyone in the shadow of it is not protected as much. Every shadow is a place the virus can lurk, on a surface or in the air. Putting far UVC LED's in places like air conditioners and HVAC systems may make some sense. Putting them in rooms may not, although they would reduce risk to some extent, even though they won't have full coverage. The safety of far-UVC has not been extensively tested, yet it is already being deployed:
An amount of light will be reflected by the walls. So it will get to most shadowed places too. Of course, a much larger exposure time will be needed to be effective there.
You can easily check that there is no true pitch black shadow open place in a room, this is the whole idea behind "global illumination rendering".
If it reflects at the walls it looses energy and isnt UVC anymore …maybe uvb …. Thats the reason we can see uv floruelenc … 300nm( UVA) radiation that gets reduced to something like 350nm(blue light)
If true that would be terrible. Because higher wavelength UV is very dangerous.
And are you sure about this? When visible light gets reflected by a wall it doesn't seem to change wavelength significantly (color basically remains the same).
That’s not at all how reflection or fluorescence work. Reflection does not change the wavelength. Fluorescence is a three-step-process of absorption, internal conversion (energy-loss) and re-emittance of light with a higher wavelength. Fluorescence-efficiency is usually very low, and highly specific to the absorbance of a certain wavelength, so unless you have bad luck with the color of your wall, fluorescence should not be of high concern.
I would say that the re-emitted light has a “longer” wavelength. Fluorescence always produces a longer wavelength. UVC becomes UVB, UVB becomes UVA, UVA becomes blue, etc. Though different materials increase the wavelengths to different degrees. That is why “black lights” can produce different fluorescent colors.
Hmmm light is a package of photons and when it reflects and the object is blue it looses the blue spectrum(photons) in the package. This package can be disected with furier and should have a different wavelength then befor……. Are you sure thats not how it works?? I would love to be proven wrong. Had not enough physics to fully grasp that concept :)
And did you ever use a blacklight in a dark room? Many things are shining. For example teeth. So smilling could get 220nm to a dangerous zone and kill the one that is smiled at? … hehe little joke.
If the light emitted by the LEDs is "really close" to the mercury light, it should be just as carcinogenic.
I also seriously doubt that the LEDs are based on silicon since indirect bandgap semiconductors make horribly inefficient light sources. Also the bandgap of silicon is somewhere in the near infrared.
Frequency doubling requires exteremely high intensites that are usually only reached by focussed laser beams. I don't see how one could use it in a LED.
> BUT about 10 years ago, it became practical to use frequency doubling in LEDs to generate light really close to the mercury light - the LEDs are not carcinogenic and cataractogenic.
What makes the LED light not dangerous that way? As far as I understand, what makes UVC effective is also what makes it dangerous.
I did the same as the parent. The answer is that mercury based UV lamps produce a spiky broad spectrum including emission lines really where you don't want them. And not very much at the frequency that is most effective at destroying RNA/DNA. 220nm is important because it's very effective at cross linking thymine.
UV LEDs can be manufactured to produce a very narrow spectrum centered on 220nm. So with an LED the total amount of UV produced is much less and doesn't include problematic frequencies that cause eye and tissue damage. Supposedly, I don't work in this space.
Note most UV LED's aren't suitable for sterilization. If it comes in a plastic case and costs 30 cents, it's certainly not.
Full disclosure: I'm the founder of UVX Inc., a University of British Columbia company integrating Far-UVC technology into smart devices.
Unfortunately, current state-of-the-art UV LEDs do not produce enough power at the 220nm wavelength to be commercially viable.
The current state-of-the-art uses KrCl excimer lamps to generate this light, with optical filters to eliminate spillage in the undesired frequencies (> 230nm).
Hmmm sorry that doesnt seem right. If it is the same wavelength it should have the same properties. You can add waves so that they add up to a new wave. But it is still a uv wave.
Maybe the intensity is less…. :). Or the range of uv is more specific.
Lol! Yeah, UV light from mercury gives you cancer, but the same electromagnetic radiation from LEDs is totally harmless! LEDs are green, haven’t you heard?
The very careful wording makes me somewhat suspicious. For example, they focus on the skin safety of far-UVC, but what about long term effects on the cornea?
Skin safety was a common concern for conventional UVC, and far-UVC has been anticipated to solve this problem so it is focused here.
They are saying the light waves can't penetrate the fist layer of skin... which presumably includes the first layer of eye-ball skin. If true, there shouldn't be any impact to the cornea over time
I think this is an oversimplification. The cornea differs quite a bit from skin histologically. Even if light does stop at the first layer of the cornea - the question is how? The problem typically found with UV wavelengths is opacification of the cornea/lens (cataracts). I have no idea if this is the case for the specific wavelength in the paper - but it’s definitely worth more discussion
All their citations have to do with skin penetration. The one that even mentioned the cornea only did so in reference the amount of UVC reaching the lens. These authors make claims which, while possibly true, are not found in their cited literature. For example, they say far UVC cannot penetrate the tear layer. Their citation doesn't say that. The citation says it's unlikely to damage human cells between 10 and 25 micrometers in diameter. The tear layer averages three micrometers in thickness, and it does not contain the absorptive proteins responsible for the shallow flesh penetration depth. This is shoddy science.
Chronic exposure to 240nm light causes keratopathies. 222nm is not 240nm of course but I would demand a better study before I agreed to 40+ hours a week of exposure to far-UVC.
The article links to https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC5552051/ that states "Therefore, penetration of far-UVC ~200-nm light through the cornea to the lens is Predicted to be essentially zero (15)." 15 is titled: "UV absorbance of the human cornea in the 240- to 400-nm range." Further, the main claim is "in microbes that are much smaller in size than human cells [less than 1 μm in diameter, compared to the diameter of typical human cells ranging from about 10–25 μm], [far UVC] is strongly absorbed by the proteins in the cytoplasm of human cells and is drastically attenuated before reaching the human cell nucleus" DNA and other proteins are known to be more affected by 220 nm due to absorption peaks than 254 nm. From https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradia... : 'Another potential danger is the UV production of ozone, which can be harmful when inhaled. Lamps designed to release UV and higher frequencies are doped so that any UV light below 254 nm wavelengths will not be released, to minimize ozone production.' The lights are most applicable placed at the at the coils and drain pans of cooling systems as 'forced air systems by design impede line-of-sight, thus creating areas of the environment that will be shaded from the UV light.' https://pubmed.ncbi.nlm.nih.gov/28941399/ concluded 280 nm worked better than 265 nm for water disinfection.
All deep UV wavelengths are energetic enough to break chemical bonds and the cross sections have quite non-trivial wavelength dependences. The authors of the article claim that 222 nm has a much shorter absorption length in tissue than 254 nm. This would drastically reduce the intensity that can reach the living cells under the outer layers of the skin.
Is it standard practice for commercial HVAC to have some kind of UV light/ozone/X pathogen killing mechanism somewhere in the ducts? Or would that only be installed on a HEPA style system going for a certified clean environment?
I would naively think that exposing the forced airflow to the treatment would be both simpler and safer than installing a system into every room with people.
It's not standard because you can just use filters.
Keep in mind the filters have to be able to filter the dead pathogens anyway (usually same size) or else you are breathing them, which isn't great either. Better than live ones for sure, but not great.
As for UV, you can add it to either residential or commercial easily (some preschools and schools I've visited added them in the past year). It doesn't make sense to install in every room, as you say.
What's the risk from dead pathogens - immune overreaction?
It's a screwball idea, but I wonder if there might actually be health benefits to reliably killing pathogens without filtering them out of the air - sort of like low-dose inactivated-agent vaccines for everything you would have actually been exposed to otherwise.
UV can kill stuff that gets through the filters. Even HEPA filters go down to objects of a certain size, and some viruses are smaller than that. But UV can kill even those smaller viruses.
HEPA filters block particles smaller than it's rated size, and they block those particles more easily than larger particles because of Brownian motion and the physics of electrostatically capturing particles.
They can block smaller particles, yes. But it’s non-deterministic. More importantly, they don’t block all or even most of the smaller particles. If they did, then they would be rated for the smaller particles that they are blocking.
N95 filters are rated based on how many 0.3-micron particles they can block. They are rated for that particle size because that particle size is the hardest particle size to block and therefore serves as a proper test of the filter's efficiency.
If you look at a graph of the blocking efficiency of an N95 filter vs particle size, that graph is a curvy "V" shape, with the bottom of that "V" being at 0.3 microns.
This is like theoretically true but mostly useless.
There is filtration beyond even HEPA.
For example, MERV-20 is 99.9999% efficient at 0.1->0.2um particle sizes.
It is 99.99% efficient at particle sizes like 0.01um.
The bigger issue is not whether you can get filters to do it, it's whether your system was built for the pressure drop you'd need to do it.
IE UV's advantage is that it doesn't really drop pressure (but does require some dwell time), not that you can't filter air well enough.
I was referring to standalone systems that are designed to filter all the air in a room, and use so-called “HyperHEPA” filters to get particles way below the size that HEPA is designed for. Of course you can also get higher filtration rating filters to attach to your whole-house air handling units, and — as you point out — those would have to be sized and designed for that. But the whole house units weren’t what I was talking about.
That would treat the ducted air but it wouldn't treat the air already in the room. And if the air is being recycled, it would still linger for some bounded time before being pumped back through treatment.
Having the UV in the room with the people means it treats every breath immediately.
I work in this field (infection control) and see a lot of products being pushed, especially lately.
One we actually installed in our hospital is a replacement for the regular fluorescent lights you see in every building. It's a direct swap out so pretty easy for any maintenance crew to complete. Instead of directing the UV light into the room, it simply has a duct inside with a fan that directs air to pass by powerful UV lights. The UV light is contained to a small box within the unit and the people around never are exposed. The only drawback is the fan noise, but in hospitals, the background sound is already pretty high. I believe you can schedule the fan to stop overnight. Otherwise it basically continuously circulates the air in the room, always passing over a UV source to kill pathogens that might be in the air.
This is a different purpose. These units aren't connected to the facility HVAC system at all. If I could remember the name I would link the companies website.
We have UV filters on our HVAC units here at our house, in addition to the whole-house HEPA filters. They’re expensive, but if you have a lot of allergies, IMO they are well worth the extra cost.
Bacteria is a lot more difficult to kill because of the size. This is great for viruses though. I've always wondered about the effectiveness of UVC, humidity, and ozone for the control of COVID.
It does sound as they say "promising" but when do they do the big, decades long double blind, randomized, controlled study of long term effects? What if you have a wound in your skin, does it become cancerous because the live cells are exposed to far UVC light? What does it do to plastics? Do humans get sick easier if they are living in a sterile environment? Does it kill plants? Far UVC is not a natural phenomena on Earth.
As I understand it, the usual design of systems that use UV light to kill viruses do not simply shine it into the room like a ceiling light; rather there's a box with a UV light in it, and a fan to draw air through that box.
Seems like a way to risky idea… gut feeling. And there are problems. First the uv has to reach the virus. If there are shadows its over. Its super hard to ilumate a room perfektly…. And may i propose an alternative. Use a hepa filter that changes the air in the room at a rate that would make in impossible to have much virus in the air… also not that easy but imho way safer than UVC
Eh, not techy and sparkly enough. It won't convince the laypeople that they're safe enough if the only palpable aspect of the system is a slight breeze.
As kind of an echo of radu_floricica's comment upthread: dismissing some X because some other people allegedly will have unreasonable concerns, that's another disease of discourse we get too much of. I wish people would restrain themselves from bringing up that kind of alleged obstacle until after getting to some kind of rough consensus at the object level.
It's like a recipe for "We can't ever improve anything unless, somehow, magically, there's already common knowledge of the fix." The object-level talk is necessary to getting to common knowledge!
How many ways I hate your comment? let me count the ways.
1. Somebody comes with a potentially awesome idea, you have a gut feeling it's risky, and start looking for confirmations of your gut feeling. Way to #hit on somebody else's initiative.
2. "The virus" (we all know we aren't talking about tuberculosis here) is airborne, which means it'll float around. If there are shadows it's not "over", it what scenario it would even mean anything for shadows to be game over? An instantaneous flash once?
3. An alternative is not an argument. Hepa filters work, and I completely agree that we should be using them a lot more but:
3.1 We aren't using them a lot more, so for some reason they don't fix the problem, so alternate solutions are very welcome
3.2 There's room for more than one took in a toolkit, for reasons too obvious to get into.
----------------
Now why am I taking the time to write a comment 5x the length of yours? Because you're merely doing in a somewhat more obvious and inexperienced way what society has been doing for... at least a couple dozen years. Anything new is risky, we should carefully study side effects and only when it's clear there aren't any we're allowed to move forward. This is especially true for medical tech, but it's part of a larger disease that's in the same constellation with NIMBY, regulatory capture and taxi medallions being worth a million.
Covid made it obvious that a lot of emperors didn't wear clothes. We could have had mRNA vaccines quite a bit earlier - and I'm sure the companies involved would have been perfectly happy to make money from them. But no, there had to be a pandemic for regulatory agencies to even consider approving such new tech.
We could have had WFH ten years ago, the tech was here. It took barely weeks for IT departments and worflows to adapt. But no, managers had to negotiate in the strictest terms for even one day a week of WFH, because it's Something That Is Not Done.
And you have a gut feeling that it's risky tech, and I get triggered.
> there had to be a pandemic for regulatory agencies to even consider approving such new tech.
That’s nonsense. There were no regulatory agencies blocking mRNA vaccines. There has been a path towards their approval for a long time. And products such as EndeavorRx, a therapy delivered as a video game, show that FDA is willing to create paths for novel types of therapies in recent years.
Between the forever chemicals, microplastics and air pollution we already have quite enough "good ideas" trying to kill us. The burden of proof for any potentially hazardous new invention is on the inventor to prove that it is safe.
People who are dismissive of new ideas based on safety grounds don't need to provide reasoning or evidence or even a coherent argument, they provide a useful function nonetheless by adding friction, forcing inventors to prove that their invention is safe beyond doubt. Since this idea proposes using ionizing radiation around people, a strong dose of scepticism is warranted.
Dude first I didnt want to trigger you and I apreciate your comment. But isnt saying its a gut feeling somehow communicating it is understood that this isnt the standpoint of a scientist? Thats mostly common sense. So why go into ragemod on sth I did state as something not to take seriously?
But you made a long comment so I will take the time to engage with you.
1. a potential awesome idea it isnt. Uvc is very strong and every layman should now that it can kill bacteria and viruses … it can even split chemical bonds. And a it should be known that it creates ozon and could cause cancer. But this is a question of the intensity. And also as the ozon layer filters uvc we dont have much contact. But it is safe to asume that if UVA and UVB are causing cancer so should UVC … the next lvl of higher energy is X-ray and gamma and beta. Funny stuff
2. a scenario where to people are talking to each other and the uv cant radiate between them.
3 I did propose the hepa filter because the problem is the following. You have a rate of virus getting in the air and a rate it is killed by uv light and a rate of it is absorbed by the hepa filter. So imho a room were air can circulate easily there should be a possibility of getting to the rate that the air in the room is changed sufficent quickly to not get anough virus to make people ill.
UV light is a good choice and allready used in hospitals and cheap. But when nobody is there. But i still dont think its a good idea to throw high energy radiation onto people just to be safe.
3.1 they are expensiv and getting to a solution is not what this society is made for
3.2 i totaly agree with you and every option should be validated.
But do I have the right to an opinion? I dont want to disrupt the discussion about potentialy helping ideas. But when someone stats a doubt it would be nice to answer polite and engaging on the doubt.
And I understand you have a history that made you get triggered but dude … I am not part of that history.
Wish you the best
Edit: ar last i want to state that the succes of a medicine to finish phase three is like 1-5% … so good that we have those mechanics to prevent harm to society… but this is a old discusion
Yeah, should have made it more clear that it's not personal.
But look at the other comments. Look at what zarzavat is saying below. "The burden is on the inventor" - and since he mentions microplastics, I'm allowed to assume he's talking about high levels of certainty and second order effects.
This has never been true in the whole human history. Ever.
This itself, this "being certain every innovation is 100% harmless" is a huge departure from how things have been done, and in itself has a huge risk. I'm not talking about not having shiny new cool stuff, or not having a colony on Mars. I'm talking about apples and apples - about this kind of meta-strategies just plain costing more lives than they save. Google "FDA delenda est", for smarter people than me saying that FDA was way too conservative in the pandemic.
Somebody said below that I'm mistaken about regulatory agencies delaying mRNA before the pandemic. We could of course try and get into the gritty details about what they delayed and why, but just consider one thing: Moderna had their covid vaccine ready in a matter of WEEKS. And it's the same vaccine we're using now. I don't know without googling when Pfizer had their first version, but I imagine it's around the same timeframe. Does this sound like immature technology? When two companies immediately come up with a vaccine when really needed?
What is more likely, that it somehow happened right now for god knows what reason, or that they were both ready to use mRNA but couldn't?
And people keep dying around us. Of Covid, of cancer, of dozen of diseases, not to mention plain old age. This is not about micro-plastics - it's lives vs lives. We have (all around the world) a much more conservative system than we need.
That I can partly sign. The complexity is way out of controll and it is way to hard to get stuff done with all regulation. But somehow we need regulations. So where is the golden way? If we overregulate people will shout that potentialy beneficial things wont happen…. On the other side if we dont regulate people could be killed with harmfull stuff that could be prevented.
Honestly this question is puzzling me since a while and I cant even state a direction I would take because its to complex for me….. but gut feeling says more transparancy and less complexity could work in designated areas… but … gut feeling.
And as said I understand your first rage. With the past years we are all on the edge with strangers, me too. And I did somehow mumble a bit …
Edit: to the vaccine part. It seems easy to develop them. A friend working at a well known biotech lab was even thinking about making one on the fast way for himself. The hard part is to scale the production and have a good one. As far as I remember those two werent the only ones… but those that worked well.
But at first I was rly impressed that they got it that fast and then I was even more impressed about the scalling problem. My friend told me about it and it was fascinating.
Yeah, home-made vaccines are a thing, but they're usually made of inactivated viruses and have some disadvantages if used on a large scale. Still a fair option, and probably one we could have used early on for populations very much at risk, where the cost-benefit is worth it.
Problem is we don't do cost-benefit anymore. With Covid, pretty much any measure they approve becomes very soon mandatory. Vaccines approved for children? Vaccines are now mandatory for children (or strongly encouraged, depending on country).
That's... I don't even know how to call it. Bureaucratic thinking? A properly medical approach would be to have a bunch of tools with various degrees of risk and use them as needed. It's ok if individual doctors have to make more complex decisions. It's ok if guidelines are longer than one page.
Currently they seem to avoid allowing anything more complex than can be explained on TV.
“[…] far-UVC light cannot penetrate even the outer (non living) layers of human skin or eye; ”
Without reading their previous reference, this doesn't make sense. If it doesn't reach the outer layers, what’s blocking the light?
Also, I seriously doubt this wont cause cataracts in the long term.
By Wiki, light < 200 nm is absorbed by O2. The light proposed by the authors is 207< \lambda < 222, so about as energetic as UV can be and not be blocked by the atmosphere. Ill take their word that it cant make it past the layer of dead skin.
But what protects the cornea? Just the very thin layer of tears?
Turn up the HVAC air exchange rate please! There are many other benefits to that.
If this does indeed take off, we may expect the next trend in fashion to be clothing with with stripes and other features that fluoresce under said UVC light.
I have a question. Does anybody know why we keep our indoor light sources uva / uvb free ?
I know that too much UVA/B light seems to be carciogenic, but a small amount of it, especially UVB seems to be beneficial to human and still kills germs, especially covid [1]
The positive effects are
a) vitamin d production
b) germicide
The negative effects are
c) lower energy efficiency in the visible spectrum (watt per visible light produced)
d) negative effect on the eye
e) carciogenic
For indoor keeping of reptiles UVB light seems to be needed [2]
As far as i've read, for indoor planting, UV light seems to beneficial as well, for example it increases the production of THC [3]
Why should we, as humans, be different ?
[1]Ratnesar-shumate, S.; Williams, G.; Green, B.; Krause, M.; Holland, B.; Wood, S.; Bohannon, J.; Boydston, J.; Freeburger, D.; Hooper, I.; Beck, K.; Yeager, J.; Altamura, L. A.; Biryukov, J.; Yolitz, J.; Schuit, M.; Wahl, V.; Hevey, M.; Dabisch, P. Simulated Sunlight Rapidly Inactivates SARS-CoV-2 on Surfaces. J. Infect. Dis. 2020, 222 (2), 214–222.Google Scholar
https://sci-hub.st/https://doi.org/10.1093/infdis/jiaa274
if i had to guess there are a few reasons they don't do this...
the first and most important reason is manufacturers have and will optimize for the main benefit of a product. the main product here is light. heat came as a negative byproduct of traditional incandescent lights and heat is something to minimize to lengthen the life of an led bulb.
another possibility is that if it were widespread it could cause some negative outcomes of people sitting too closely to a source of it and potentially exposing the companies to legal issues. not a lawyer and they might be able to shield themselves from that liability with well written disclaimers though.
Along with inertia from the incandescent bulbs not emitting that wavelength... the most likely reason is that they don't want to spend the money on researching how safe it is and how to cost effectively make them like that though.
UV A/B is oxidizing, which is why plastics left outside degrade rapidly, discoloration occurs, etc. It's bad for your eyes, bad for your skin in excess, and creates ozone in the air which is an environmental pollutant.
Normal indoor plants have no need for UV at all. Nor do most food plants -- greenhouse glass blocks UV, for instance.
I don't think germicide is necessarily good. There are theories that the abundance of allergies and autoimmune diseases is partially caused by excessive cleanliness/lack of exposure to microbes etc.
I think allergies and autoimmune diseases are partially caused by the fact that people are no longer work infested with parasites in yhe way they were all the time since forever. Parasites suppress immune responses.
I think we should figure out how to substitute their influence on humans before we conclude that exposing ourselves to bacteria and viruses a lot is a good thing.
CFL bulbs, especially earlier versions often emitted a surprising amount of UV light. The speculation is that the tight coils of glass would result in breaks in the phosphor coating, letting the UV through.
I know I have fixtures that used to have CFLs in them, and any plastic is yellowed significantly.
UV in fluorescent bulbs escapes directly through the phosphor itself. No phosphor is 100 opaque to UV, nor does any phosphor convert 100% of UV to visible light.
Some phosphor coatings might be better than others, but they will all leak a certain amount of UV.
There's some misinformation that claims to "kill COVID" (which is a symptom not a virus) so therefore the recommendation is to say "deactivates SARS-COV-2".
Personally I've been trying to reach out to people with scanning electron microscopes, because there's a hypothesis that I'd like to test.
VisualCapitalist have an infographic showing the size of particles, including coronaviruses as 0.1-0.5 microns. I'd assumed a Gaussian bell curve centred around 0.3 micron, but was kindly corrected here on HN that SARS-COV-2 is closer to 0.1 micron.
My hypothesis is that UV-C light at 300 nm = 0.3 micron, or 100 nm = 0.1 micron, will cause the particles to resonate.
In a less formal way, play them the right beat and make the virus dance itself to pieces.
To that end, I bought some UV-C lamps (safely inside plastic boxes) from an aquarium shop. Air filters are all sold out in New Zealand, and suppliers are on holiday. The seller understood, but warned that it can cause sunburn within seconds, and eye damage - so don't look into the blue light! This makes sense because of the size of rod cells in the eye.
Then I got a regular PC fan, and ran it overnight, blowing air through the light. It felt like the air became very dry, and increasingly unpleasant.
Although it didn't smell "fresh", and the window was open for some ventilation, I'm a little worried about ozone production. Not sure how to test that though.
Fabric filters in HVAC will work according to their feature size (like an N95 vs surgical mask), but the difficulty is remembering to change them. So personally I still think UV-C is the solution, I just don't know how to use it safely yet. Certainly it makes sense for disinfecting the mask recycling bins (biohazard infectious substances taken out of the environment = litter picked up) but for ambient air, I'm still learning how to do that safely.
Use both UV and good quality HEPA filters, if you can.
Heck, you can even get filters that greatly exceed the filtration capacity of HEPA filters, and get objects down to .01 microns, which is a tenth to a thirtieth of the size you’re projecting for the smaller particles.
But they are expensive. If you’re interested, look at the IQAir brand.
There's some that were being thrown away at work during the office clear-out before the Christmas holiday, so I do have some filters! Today I went back and tidied up the boxes and found them. Need to figure out how to make an air-tight seal in a cardboard box though; I'm no expert at 3D printing real parts (and I'd need to book time on the Ultimaker or laser cutter).
Full disclosure: I'm the founder of UVX Inc., a University of British Columbia company integrating Far-UVC technology into smart devices.
We're looking to ship out units within the next month, here is where you can learn more (https://www.uvxinc.com). I'd love to hear your thoughts/feedback!
It seems as though you are targeting companies with your contact us for further information buttons. I'd like to find out how much this would cost to install in a home? Are you B2B only?
Our existing product is B2B, yes, but we got a lot of interest from consumers too and are considering a consumer product line (for which we're doing customer interviews to get insights/feedback). If you have 20-mins to share your thoughts, we'd love to hear from you :)
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[ 4.0 ms ] story [ 161 ms ] thread>However, the widespread use of germicidal ultraviolet light in public settings has been very limited because conventional UVC light sources are a human health hazard, being both carcinogenic and cataractogenic
conventional UVC is generated by mercury light bulbs and are carcinogenic and cataractogenic
BUT about 10 years ago, it became practical to use frequency doubling in LEDs to generate light really close to the mercury light - the LEDs are not carcinogenic and cataractogenic. When you read about UVC effects, you should check what type of light source they are using (mercury vs LED)
Also, it is the advancements in silicon manufacturing that has made it cheaper to make new and different LEDs - such as these "far-UVCs". It is pretty legit!
There is "a lot" of research demonstrating effectiveness of "conventional UVC", but not a lot on "far-UVC". One of the limitations on both is the shadow effect... got to go. I'll elaborate if there is interest
Yes please
https://theblindhorse.com/the-blind-horse-becomes-first-rest...
You can easily check that there is no true pitch black shadow open place in a room, this is the whole idea behind "global illumination rendering".
And are you sure about this? When visible light gets reflected by a wall it doesn't seem to change wavelength significantly (color basically remains the same).
https://wonderopolis.org/wonder/why-does-a-black-light-make-...
I would say that the re-emitted light has a “longer” wavelength. Fluorescence always produces a longer wavelength. UVC becomes UVB, UVB becomes UVA, UVA becomes blue, etc. Though different materials increase the wavelengths to different degrees. That is why “black lights” can produce different fluorescent colors.
And did you ever use a blacklight in a dark room? Many things are shining. For example teeth. So smilling could get 220nm to a dangerous zone and kill the one that is smiled at? … hehe little joke.
I'm imagining a washing machine full of masks (COVID concentrators), beaming UV-C light at them as they spin around.
Would that mitigate some of the shadow effect, because they're in motion?
I also seriously doubt that the LEDs are based on silicon since indirect bandgap semiconductors make horribly inefficient light sources. Also the bandgap of silicon is somewhere in the near infrared.
Frequency doubling requires exteremely high intensites that are usually only reached by focussed laser beams. I don't see how one could use it in a LED.
What makes the LED light not dangerous that way? As far as I understand, what makes UVC effective is also what makes it dangerous.
UV LEDs can be manufactured to produce a very narrow spectrum centered on 220nm. So with an LED the total amount of UV produced is much less and doesn't include problematic frequencies that cause eye and tissue damage. Supposedly, I don't work in this space.
Note most UV LED's aren't suitable for sterilization. If it comes in a plastic case and costs 30 cents, it's certainly not.
Does anyone know of any manufacturer? I don't think they exist yet?
Unfortunately, current state-of-the-art UV LEDs do not produce enough power at the 220nm wavelength to be commercially viable.
The current state-of-the-art uses KrCl excimer lamps to generate this light, with optical filters to eliminate spillage in the undesired frequencies (> 230nm).
> KrCl excimer lamps
https://en.wikipedia.org/wiki/Excimer_lamp
Maybe the intensity is less…. :). Or the range of uv is more specific.
Lol! Yeah, UV light from mercury gives you cancer, but the same electromagnetic radiation from LEDs is totally harmless! LEDs are green, haven’t you heard?
A single wavelength emission from a far-UVC led source is therefore safer.
I don’t know why it hasn’t been productive since the start of the pandemic.
They are saying the light waves can't penetrate the fist layer of skin... which presumably includes the first layer of eye-ball skin. If true, there shouldn't be any impact to the cornea over time
Chronic exposure to 240nm light causes keratopathies. 222nm is not 240nm of course but I would demand a better study before I agreed to 40+ hours a week of exposure to far-UVC.
https://media.springernature.com/full/springer-static/image/...
I would naively think that exposing the forced airflow to the treatment would be both simpler and safer than installing a system into every room with people.
Keep in mind the filters have to be able to filter the dead pathogens anyway (usually same size) or else you are breathing them, which isn't great either. Better than live ones for sure, but not great.
As for UV, you can add it to either residential or commercial easily (some preschools and schools I've visited added them in the past year). It doesn't make sense to install in every room, as you say.
On ozone, see https://www.epa.gov/coronavirus/air-cleaners-hvac-filters-an... and the section on ozone.
It's a screwball idea, but I wonder if there might actually be health benefits to reliably killing pathogens without filtering them out of the air - sort of like low-dose inactivated-agent vaccines for everything you would have actually been exposed to otherwise.
If you look at a graph of the blocking efficiency of an N95 filter vs particle size, that graph is a curvy "V" shape, with the bottom of that "V" being at 0.3 microns.
The bigger issue is not whether you can get filters to do it, it's whether your system was built for the pressure drop you'd need to do it.
IE UV's advantage is that it doesn't really drop pressure (but does require some dwell time), not that you can't filter air well enough.
Having the UV in the room with the people means it treats every breath immediately.
Most places with lots of people also have very high acph - often 20-30 air changes per hour.
One we actually installed in our hospital is a replacement for the regular fluorescent lights you see in every building. It's a direct swap out so pretty easy for any maintenance crew to complete. Instead of directing the UV light into the room, it simply has a duct inside with a fan that directs air to pass by powerful UV lights. The UV light is contained to a small box within the unit and the people around never are exposed. The only drawback is the fan noise, but in hospitals, the background sound is already pretty high. I believe you can schedule the fan to stop overnight. Otherwise it basically continuously circulates the air in the room, always passing over a UV source to kill pathogens that might be in the air.
EDIT - just to clarify, you swap out the whole box, not just the bulb. Like this (http://2.bp.blogspot.com/-etoHnNVcOnw/Tu0xY9sDwCI/AAAAAAAAA3...) but usually in a drop ceiling.
It's like a recipe for "We can't ever improve anything unless, somehow, magically, there's already common knowledge of the fix." The object-level talk is necessary to getting to common knowledge!
1. Somebody comes with a potentially awesome idea, you have a gut feeling it's risky, and start looking for confirmations of your gut feeling. Way to #hit on somebody else's initiative.
2. "The virus" (we all know we aren't talking about tuberculosis here) is airborne, which means it'll float around. If there are shadows it's not "over", it what scenario it would even mean anything for shadows to be game over? An instantaneous flash once?
3. An alternative is not an argument. Hepa filters work, and I completely agree that we should be using them a lot more but:
3.1 We aren't using them a lot more, so for some reason they don't fix the problem, so alternate solutions are very welcome
3.2 There's room for more than one took in a toolkit, for reasons too obvious to get into.
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Now why am I taking the time to write a comment 5x the length of yours? Because you're merely doing in a somewhat more obvious and inexperienced way what society has been doing for... at least a couple dozen years. Anything new is risky, we should carefully study side effects and only when it's clear there aren't any we're allowed to move forward. This is especially true for medical tech, but it's part of a larger disease that's in the same constellation with NIMBY, regulatory capture and taxi medallions being worth a million.
Covid made it obvious that a lot of emperors didn't wear clothes. We could have had mRNA vaccines quite a bit earlier - and I'm sure the companies involved would have been perfectly happy to make money from them. But no, there had to be a pandemic for regulatory agencies to even consider approving such new tech.
We could have had WFH ten years ago, the tech was here. It took barely weeks for IT departments and worflows to adapt. But no, managers had to negotiate in the strictest terms for even one day a week of WFH, because it's Something That Is Not Done.
And you have a gut feeling that it's risky tech, and I get triggered.
That’s nonsense. There were no regulatory agencies blocking mRNA vaccines. There has been a path towards their approval for a long time. And products such as EndeavorRx, a therapy delivered as a video game, show that FDA is willing to create paths for novel types of therapies in recent years.
QED
People who are dismissive of new ideas based on safety grounds don't need to provide reasoning or evidence or even a coherent argument, they provide a useful function nonetheless by adding friction, forcing inventors to prove that their invention is safe beyond doubt. Since this idea proposes using ionizing radiation around people, a strong dose of scepticism is warranted.
But you made a long comment so I will take the time to engage with you.
1. a potential awesome idea it isnt. Uvc is very strong and every layman should now that it can kill bacteria and viruses … it can even split chemical bonds. And a it should be known that it creates ozon and could cause cancer. But this is a question of the intensity. And also as the ozon layer filters uvc we dont have much contact. But it is safe to asume that if UVA and UVB are causing cancer so should UVC … the next lvl of higher energy is X-ray and gamma and beta. Funny stuff
2. a scenario where to people are talking to each other and the uv cant radiate between them.
3 I did propose the hepa filter because the problem is the following. You have a rate of virus getting in the air and a rate it is killed by uv light and a rate of it is absorbed by the hepa filter. So imho a room were air can circulate easily there should be a possibility of getting to the rate that the air in the room is changed sufficent quickly to not get anough virus to make people ill. UV light is a good choice and allready used in hospitals and cheap. But when nobody is there. But i still dont think its a good idea to throw high energy radiation onto people just to be safe.
3.1 they are expensiv and getting to a solution is not what this society is made for
3.2 i totaly agree with you and every option should be validated.
But do I have the right to an opinion? I dont want to disrupt the discussion about potentialy helping ideas. But when someone stats a doubt it would be nice to answer polite and engaging on the doubt.
And I understand you have a history that made you get triggered but dude … I am not part of that history. Wish you the best
Edit: ar last i want to state that the succes of a medicine to finish phase three is like 1-5% … so good that we have those mechanics to prevent harm to society… but this is a old discusion
But look at the other comments. Look at what zarzavat is saying below. "The burden is on the inventor" - and since he mentions microplastics, I'm allowed to assume he's talking about high levels of certainty and second order effects.
This has never been true in the whole human history. Ever.
This itself, this "being certain every innovation is 100% harmless" is a huge departure from how things have been done, and in itself has a huge risk. I'm not talking about not having shiny new cool stuff, or not having a colony on Mars. I'm talking about apples and apples - about this kind of meta-strategies just plain costing more lives than they save. Google "FDA delenda est", for smarter people than me saying that FDA was way too conservative in the pandemic.
Somebody said below that I'm mistaken about regulatory agencies delaying mRNA before the pandemic. We could of course try and get into the gritty details about what they delayed and why, but just consider one thing: Moderna had their covid vaccine ready in a matter of WEEKS. And it's the same vaccine we're using now. I don't know without googling when Pfizer had their first version, but I imagine it's around the same timeframe. Does this sound like immature technology? When two companies immediately come up with a vaccine when really needed?
What is more likely, that it somehow happened right now for god knows what reason, or that they were both ready to use mRNA but couldn't?
And people keep dying around us. Of Covid, of cancer, of dozen of diseases, not to mention plain old age. This is not about micro-plastics - it's lives vs lives. We have (all around the world) a much more conservative system than we need.
Honestly this question is puzzling me since a while and I cant even state a direction I would take because its to complex for me….. but gut feeling says more transparancy and less complexity could work in designated areas… but … gut feeling.
And as said I understand your first rage. With the past years we are all on the edge with strangers, me too. And I did somehow mumble a bit …
Edit: to the vaccine part. It seems easy to develop them. A friend working at a well known biotech lab was even thinking about making one on the fast way for himself. The hard part is to scale the production and have a good one. As far as I remember those two werent the only ones… but those that worked well. But at first I was rly impressed that they got it that fast and then I was even more impressed about the scalling problem. My friend told me about it and it was fascinating.
Problem is we don't do cost-benefit anymore. With Covid, pretty much any measure they approve becomes very soon mandatory. Vaccines approved for children? Vaccines are now mandatory for children (or strongly encouraged, depending on country).
That's... I don't even know how to call it. Bureaucratic thinking? A properly medical approach would be to have a bunch of tools with various degrees of risk and use them as needed. It's ok if individual doctors have to make more complex decisions. It's ok if guidelines are longer than one page.
Currently they seem to avoid allowing anything more complex than can be explained on TV.
Without reading their previous reference, this doesn't make sense. If it doesn't reach the outer layers, what’s blocking the light?
Also, I seriously doubt this wont cause cataracts in the long term.
By Wiki, light < 200 nm is absorbed by O2. The light proposed by the authors is 207< \lambda < 222, so about as energetic as UV can be and not be blocked by the atmosphere. Ill take their word that it cant make it past the layer of dead skin.
But what protects the cornea? Just the very thin layer of tears?
Turn up the HVAC air exchange rate please! There are many other benefits to that.
https://youtu.be/sJVtNsezGUI
Really a great channel, some of the best microphotography out there.
The positive effects are a) vitamin d production b) germicide
The negative effects are c) lower energy efficiency in the visible spectrum (watt per visible light produced) d) negative effect on the eye e) carciogenic
For indoor keeping of reptiles UVB light seems to be needed [2] As far as i've read, for indoor planting, UV light seems to beneficial as well, for example it increases the production of THC [3]
Why should we, as humans, be different ?
[1]Ratnesar-shumate, S.; Williams, G.; Green, B.; Krause, M.; Holland, B.; Wood, S.; Bohannon, J.; Boydston, J.; Freeburger, D.; Hooper, I.; Beck, K.; Yeager, J.; Altamura, L. A.; Biryukov, J.; Yolitz, J.; Schuit, M.; Wahl, V.; Hevey, M.; Dabisch, P. Simulated Sunlight Rapidly Inactivates SARS-CoV-2 on Surfaces. J. Infect. Dis. 2020, 222 (2), 214–222.Google Scholar https://sci-hub.st/https://doi.org/10.1093/infdis/jiaa274
[2] https://en.wikipedia.org/wiki/Ultraviolet#UVB
[3] https://vanessa-nielsen.com/cannabis-plants-uv-light/
the first and most important reason is manufacturers have and will optimize for the main benefit of a product. the main product here is light. heat came as a negative byproduct of traditional incandescent lights and heat is something to minimize to lengthen the life of an led bulb.
another possibility is that if it were widespread it could cause some negative outcomes of people sitting too closely to a source of it and potentially exposing the companies to legal issues. not a lawyer and they might be able to shield themselves from that liability with well written disclaimers though.
Along with inertia from the incandescent bulbs not emitting that wavelength... the most likely reason is that they don't want to spend the money on researching how safe it is and how to cost effectively make them like that though.
Normal indoor plants have no need for UV at all. Nor do most food plants -- greenhouse glass blocks UV, for instance.
I think we should figure out how to substitute their influence on humans before we conclude that exposing ourselves to bacteria and viruses a lot is a good thing.
I know I have fixtures that used to have CFLs in them, and any plastic is yellowed significantly.
Some phosphor coatings might be better than others, but they will all leak a certain amount of UV.
There's some misinformation that claims to "kill COVID" (which is a symptom not a virus) so therefore the recommendation is to say "deactivates SARS-COV-2".
Personally I've been trying to reach out to people with scanning electron microscopes, because there's a hypothesis that I'd like to test.
VisualCapitalist have an infographic showing the size of particles, including coronaviruses as 0.1-0.5 microns. I'd assumed a Gaussian bell curve centred around 0.3 micron, but was kindly corrected here on HN that SARS-COV-2 is closer to 0.1 micron.
My hypothesis is that UV-C light at 300 nm = 0.3 micron, or 100 nm = 0.1 micron, will cause the particles to resonate.
In a less formal way, play them the right beat and make the virus dance itself to pieces.
To that end, I bought some UV-C lamps (safely inside plastic boxes) from an aquarium shop. Air filters are all sold out in New Zealand, and suppliers are on holiday. The seller understood, but warned that it can cause sunburn within seconds, and eye damage - so don't look into the blue light! This makes sense because of the size of rod cells in the eye.
Then I got a regular PC fan, and ran it overnight, blowing air through the light. It felt like the air became very dry, and increasingly unpleasant.
Although it didn't smell "fresh", and the window was open for some ventilation, I'm a little worried about ozone production. Not sure how to test that though.
Fabric filters in HVAC will work according to their feature size (like an N95 vs surgical mask), but the difficulty is remembering to change them. So personally I still think UV-C is the solution, I just don't know how to use it safely yet. Certainly it makes sense for disinfecting the mask recycling bins (biohazard infectious substances taken out of the environment = litter picked up) but for ambient air, I'm still learning how to do that safely.
Heck, you can even get filters that greatly exceed the filtration capacity of HEPA filters, and get objects down to .01 microns, which is a tenth to a thirtieth of the size you’re projecting for the smaller particles.
But they are expensive. If you’re interested, look at the IQAir brand.
We're looking to ship out units within the next month, here is where you can learn more (https://www.uvxinc.com). I'd love to hear your thoughts/feedback!
1) How do you deal with the toxic ozone gas that's produced, and
2) How do you prevent eye damage from happening when you look at the device?