New type of ultraviolet light makes indoor air as safe as outdoors | Hacker News Reader

New type of ultraviolet light makes indoor air as safe as outdoors

cuimc.columbia.edu

162 pointssolarmist133 comments

> About a decade ago, Columbia University scientists proposed that a different type of UVC light, known as far-UVC light, would be just as efficient at destroying bacteria and viruses but without the safety concerns of conventional germicidal UVC.

Why does everyone keep calling this "new"? I've seen it published in articles seemingly everywhere within the past few days. It's not a new technology; Boeing was prototyping this in their fleet several years ago[1].

[1] https://www.cbsnews.com/news/boeings-self-cleaning-lavatory-...

It is like Hacker News articles. Sometimes an article will have an upvote or two and few comments and sink from news, and then it gets reposted a couple of years later and there's hundreds of votes and tons of discussions.

Why?

Probably this makes advertisement more successful.

I think what's new is that they can add 'kills COVID' and it will be republished on news sites with little thought.

The study looks like it's about the efficacy of putting commercially available lights in real world rooms. Really it's just the headline that says "new type".

I think in a colloquial sense, this is fair I think. They are pretty new. If it's something some people have been trialling within the last few years, that's pretty new to me. Especially in the context of "a light".

Wow, a simple search on Amazon even pulled up far uvc lamps.

Be very careful with those; retinas are particularly susceptible to UVC, as the atmosphere blocks all of it; we've never evolutionarily had to deal with it before. https://www.nbcnews.com/health/health-news/doctors-warn-abou...

So wouldn't that apply to the lights described in the article this thread is about? How can the article say those are safe?

The article describes "far-UVC" light, which they say is new.

> Far-UVC light has a shorter wavelength than conventional germicidal UVC, so it can’t penetrate into living human skin cells or eye cells. But it is equally efficient at killing bacteria and viruses, which are much smaller than human cells.

The UVC lights on Amazon are presumably plain old eye-destroying UVC.

(If you want to use UVC, get it installed in your air ducts, where eyes don't go.)

Except the comment explicitly said that amazon has "far uvc lamps".

It's new compared to the older type and isn't currently widely deployed.

Take out the words 'new type' and you are left with the idea that more conventional UV lamps have these effects.

The US patent office thought it was new:

>David J. Brenner and co-inventors have been granted a U.S. patent titled "Apparatus, method and system for selectively affecting and/or killing a virus" (US1078019B2).

For what that counts...

I don't think that counts for much.

Swinging on a swingset was patented (on a lark: https://www.newscientist.com/article/dn2178-boy-takes-swing-...) in 2000.

https://patents.google.com/patent/US6368227B1/en

"safe" in this context is virus safe. Can have a pretty good application for places where virus transmission is an issue, as long as people like me don't feel an unease about being bombarded with UV 10 hours a day.

When I think of "Safe" for air, I also think of PM2.5 and other airborne compounds. A more permanent fix to make the air fully safe is improving building ventilation.

IMO, as an armchair opinion, the LEED certification craze is much of the issue. * https://en.wikipedia.org/wiki/LEED

There's an almost blind focus on one dimension of a multi-dimensional problem. Yes, buildings should be designed to be more energy and environmentally efficient; where it makes sense. However there are many assumptions in 'building code' that evolved around implicit properties in the materials and methods used in the past.

A more comprehensive evaluation would consider numerous factors and choose trade-offs.

What is the (exterior) difference in impact between using different quantities and combinations of building materials? How do those materials need to be maintained or replaced over the life of the building? Over it's demolition? Can they be recycled or otherwise recovered?

How do the used materials and shapes effect the operational energy for the intended use of the building (over the intended, and likely, lifetimes)?

It looks like a 2014 update to LEED finally 'considers indoor environmental quality'. "... the IEQ category addresses thermal, visual, and acoustic comfort as well as indoor air quality."

However my opinion is that they've put the cart before the horse. Surely you've seen office environments where someone doesn't like 'how cold' the building is; so they use a personal heater to blow directly on themselves. Or utilize an air filtration system for one room because it's impossible to clean the ventilation ducts. It also fails to consider containment of emissions from chemical / cleaning or other smelly areas.

The acoustic angle is also critically important for apartments and condos. One of _the_ major reasons I and many others have grown to hate living in them revolves around __noise__. There are many memes about marching bands and various other sadistic neighbors on any adjacent side, particularly upstairs.

If you want people to _want_ to move to apartments and condos, then they need to be built so they're desirable. That includes 'cave of solitude' level of audio isolation. Fresh air that doesn't have the cooking or laundry smells; or worse the trash chute leaking out because someone didn't setup the pressure system correctly. It also includes no more free-for-all parking and enough spaces for the cars people will bring with them from the suburbs. (Which might be as many as 2 per adult on average!) The car angle might be solved at the same time as municipal parking, if a big enough, and well secured enough, lot exists as an IO/interface with the surrounding areas. That level of thinking combined with people-mover sidewalks along pedestrian arterials will help us move towards 'Cave of Steel' like cities.

I don't think I agree. I think the need to reduce energy use to prevent climate change is so overwhelming, that no trade off is worth it. Yes, people's health are on the line, and it's difficult to argue against that—but unchecked climate change is also going to affect the health of an awful lot of people in the future, in worse ways.

Obviously, if we can greatly improve indoor air quality with only a marginal increase in energy use, that's worth it. But anything else... I don't know! I think it's easy to forget just how big of a deal climate change is!

It's also easy to forget how big of a deal human health is. If you can spend 5% more energy to unlock 5% more enjoyment and productivity, you can use that extra productivity to engineer better, less polluting systems. If every high density apartment building had a much much higher air and sound quality than the average house, it would also entice more people to live in denser areas.

Moreover, well-built, well-conditioned, comfortable buildings are also very efficient, so the only reason not to build for quality is up-front capital cost, a problem that can be solved with a combination of improved technology and tighter building standards for ventilation and noise.

There should be a way to shop for places to live with an easily comparable air, sound, and comfort quality score, so that there is pressure to improve.

Even during the pandemic their were active protests from companies against higher standards of ventilation where I live, even though the ventilation is already inadequate. Good ventilation would prevent lock downs. An article on this in the NYT by an expert rated that most ventilation is only 3-4 on a scale of ten. 7-8 would prevent a lot of transmission.

If you want people to _want_ to move to apartments and condos, then they need to be built so they're desirable.

Yes, absolutely this. Ever since I was a kid playing Sim City and seeing the Arcologies I dreamed of living in a high rise apartment. Eventually in my 30s I was able to do so, and the whole experience was terrible. Sure, the place looked great in photos. But the lint and smells from laundry, cooking, weed, bathrooms, etc. all got funneled into my unit, and the soundproofing was nowhere near adequate.

These buildings, if they have operable windows, really need isolated per-unit ventilation systems (with a hydronic loop for heat/cold) and, as you say, dead silent soundproofing.

So now I'm back into a house with no shared walls. It's also poorly built, but it's way quieter way out here than in a city, and overall much higher quality of life. And I can still drive or take a train downtown to access food/etc.

Does anyone know why North America uses standard drywall for interior walls? It's the same in hotels, and whenever I visit it freaks me out a bit. I don't want to hear what's going on in the room next door. In Europe, interior walls between units are typically made from concrete or masonry which is much better at sound proofing.

I grew up in Taiwan on the pacific rim of fire (think earthquakes) as result buildings are ugly and concrete most of the time. And it is noise. I could hear everything and everyone and you get the strange marble dropping sound to boot too. At the end proper sound proofing worked, used multiple layers of wood and dry wall worked wonders.

Much of North America has strong earthquakes, which limits the kinds of materials you can safely use. Masonry in the US must be engineered and reinforced to survive earthquakes, which adds significant cost. Masonry construction was common in the US centuries ago, but we have a lot of experience with earthquakes doing severe damage to unreinforced masonry, so that kind of construction is prohibited in most places.

You can have very quiet buildings without masonry. I've lived in a few, all steel framing and drywall with proper sound isolation. It is all in the construction technique. Even purpose-built sound isolation rooms are little more than wood and drywall, properly engineered, anywhere on the planet.

> all steel framing and drywall

I have never heard of a steel framed / drywall house before. I looked it up and appear they are offered in my country. How does steel make it quieter? I would think steel would transmit more noise than wood.

Steel vs wood doesn't really matter. The key to soundproofing is having sound absorbing mass in between walls. As long as you fill the gaps between drywall with a decent amount of insulation it should be reasonably sound proof.

In fact many professional "sound absorbing panels" you might see in a recording studio or on the walls of movie theaters are made from insulation.

It’s illegal in many jurisdictions. Wood is fine.

Soundproofing is about insulation materials, quality doors and building above the minimum. A lot of midrise condos are built to a pretty shitty standard to make the numbers work. Sometimes they do stuff like glue wall panels instead of fastening, so you get things starting to loosen quickly as the building shifts.

If you stay in a decent midrange hotel (Hampton Inn, Marriott, etc) the sound is pretty good. They are prefabricated concrete, but look at the details, surfaces are carpeted, textured ceilings, there are rubber gaskets everywhere, etc. You usually don’t hear the nighttime adventures of your neighbors, but you can smell a bag of popcorn from 50 yards away because ventilation sucks.

Steel framing tends to be correlated with higher wall mass, which means better sound isolation.

The original discussion was about noise in multi-family homes e.g. apartment buildings and high-rises, which tend to be steel beyond a certain height. While there are single-family homes built with steel framing in the US, they are less common; they have some advantages but cost more to build and are more difficult to thermally insulate than wood.

Every multi-family high-rise I've lived in used steel construction and drywall and had excellent sound isolation -- I never hear my neighbors and vice versa.

I’ve lived in a high rise in SF with a lot of neighbors and I never heard anyone around me, nor smelled them. It’s possible.

I don't think you're getting UV10 so much, but there is real risk in the production of other chemicals, which this study is really ignoring. Improving exterior airflow and particle filtration is a much safer option.

UV strong enough to kill off pathogens will likely produce some ozone.

I have to wonder how various materials will react. A simple plastic layer on a counter could yellow and degrade very quickly. And im sure that all sorts of drugs will need to be stored in dark boxes else they too degrade into who knows what.

You could add it as another 'filter' for a general HVAC filtration & ventilation system. Nobody would actually need to be exposed to the UVC light, and you could do potentially do other wavelengths that would not be the safest to expose people to but would be more effective. It would also be good for a retrofit filter, because adding a light to an HVAC conduit means you don't need to increase the power of a current HVAC fan to push through filter material, and you'd probably wont need to replace the 'filter' that often either.

Additionally, in room units could activate only when there is nobody in a room... like reverse occupancy lights. Slight movement would switch them off. If it was really harmful, a notification could indicate they are about to come if there is no movement. This would not be appropriate for every type of room of course, but more filtration the better where it is practical.

Aside from humans, would this radiation not also screw with dyes, paints and possibly plastic coherence in a room?

Sure, I assume anything that is not UV safe could be a problem. In institutional environments, this could be planned for. A lot of plastics are coated with UV treatments already.

I believe an upside of the 'in-room' UV approach is that it also cleans exposed surfaces. Putting the UV light only in the air-ducting does little to clean a surface someone coughed on. Whereas the UV approach would help to disinfect those surfaces.

It could be useful in non-office situations too. E.g. on the London underground where you are stuck in a tim-can for 5-20 mins etc without any fresh air circulation

The obvious solution that yields 90% of the benefit at 5% of the cost is to open the window and increase ventilation. (Although admittedly not addressing particulate issues if that’s a problem)

Since most building standards are set by the society of HVAC engineers, there’s a pretty obvious bias, and efficiency people seem to take the bait. We tend to use these systems to make shittier buildings marginally ok for human habitation. Architects care about $/ft for normal buildings and cool looking designs that get them awards for fancy buildings.

> Far-UVC Light May Be Safe for Indoor Use

Emphasis mine. Look, this is promising, but the fact that they can only say it may be safe suggests that maybe we should ease off with the "zomg deploy it everywhere now!" type of rhetoric. I don't think it actually is, but good grief it feels like an astroturfing campaign in here right now.

There are PLENTY of place you could deploy this without shining them directly on people as we continue studying the details, but this isn’t a single new paper.

Also, from the article. “This reduction was achieved using Far-UVC irradiances consistent with current American Conference of Governmental Industrial Hygienists threshold limit values for skin for a continuous 8-h exposure.”

Thus has been under research for a decade now. Plus the effects of UV on humans is pretty damn well studied at this point. This is just finding the right crossover point that’s effective against microbes, but no longer dangerous against more complex organisms.

I also think we should start retrofitting all ventilation systems with UV disinfectants.

My concern is the effect on the microbes on our skin that we rely on.

Yeah, I agree with this. I've been wishing for a way to retrofit our AC with something that uses UV to scrub the air.

That already exists. It’s relatively common. I’d call your servicer and ask about it.

I already have this in my home. It wasn’t terribly expensive.

Just put it inside the HVAC system.

that already exists, but as they explain in the article you can cycle through the whole room’s air much more often if you expose the occupied room.

"May" in that context is just a weasel word that gets inserted to be cautious.

It can mean there is genuine uncertainty, but it can also be equivalent to we can't be absolutely sure the sun rises tomorrow.

> The lamps inactivated more than 98% of the airborne microbes in just five minutes.

If they only need five minutes, I guess that could mean that they don't need to be on all the time, but turned on intermittently based on room occupancy and ventilation levels.

Don’t forget that we actually need exposure to germs to train our immune systems. We don’t want to overdo sanitizing everything.

Look up the hygiene hypothesis.

Right - I also don’t like the idea of something indiscriminately killing bacteria on my skin and food. Microbiomes in and around our body shouldn’t be messed with unnecessarily IMO.

OTOH this is a type of ultraviolet exposure that we would also receive from sunlight. At least as claimed, it's not doing anything different to our microbiomes than just going outside would do.

No, it's not. You might see UV-A or UV-B in normal sunlight, but not UV-C. It is blocked by the atmosphere. That's why it's so dangerous to terrestrial life as diverse as viruses, bacteria, and human beings, as well as others.

UV-C is not something we have had frequent exposure to over the millennia, and so this is something we are not adapted to handle.

Ugh, you're absolutely correct! I retract my prior comment; thanks for the correction. And not to detract from my being flat-out wrong, but it should be noted that it's claimed that the specific 222nm wavelength of far-UVC used by these devices is not energetic enough to penetrate the skin or lens of the eyes [0][1].

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552051/

[1] https://journals.plos.org/plosone/article?id=10.1371/journal...

That's not how it works, unfortunately. Lower wavelength light has more energy and is in general more penetrating and more dangerous. But the particular behavior of any given material (due basically to resonances) can and will dominate the overall response.

Your references are rather disingenuous in that they only look at the skin, not the eyes (at least, I think that's what the abstracts are saying; I've never spoken "pretentious Latinate doctor" very well at all) and look for "typical" UV damage biomarkers... which is pretty stupid when you're not using "typical" UV light.

So, maybe safe, but the analysis so far doesn't really pass the smell test. Establishing safety of something like this, for the intensities needed, isn't an easy task.

I have no involvement in this industry, neither academically or by investment. Just on a learning journey, like many here. Disingenuous? It does me no good to deny that accusation, but I think the discourse level here is higher if we dispute each other's facts over disputing each other's motives. You appear to have a much more deeply rooted interest than I on this subject, and I have no reason to dispute your facts, but as for your opinion that "it doesn't pass the [ocular] smell test," a web search turns up, "the reason is that far-UVC light has a range in biological materials of less than a few micrometers, and thus it cannot reach living human cells in the skin or eyes, being absorbed in the skin stratum corneum or the ocular tear layer."[0]

You're undoubtedly already familiar with that so I'm sure there's some reason you have for finding it less than conclusive. In any event, I totally agree with you that the safety of this needs to be firmly established before releasing 222nm lamps for general home use, although I think a more limited use might be acceptable (for example, placing the bulb in a UV-opaque enclosure and circulating the room air through that unit).

[0] https://www.nature.com/articles/s41598-020-67211-2

To be clear, I was calling the researchers who wrote those papers disingenuous, not you. I've reviewed scientific papers. I have seen some true garbage. This is probably why I have a pretty low tolerance for bad papers or paper puffery. Those papers are skirting around inconvenient facts to make their conclusions appear stronger, which they should not be doing. Nothing is wrong per se, it's just intentionally not clear.

As an example of what I mean, take the Buonanno paper you linked. They say "We measured induction of the two most abundant premutagenic DNA lesions in the epidermis, cyclobutane pyrimidine dimers (CPD) and pyrimidine-pyrimidone 6-4 photoproducts (6-4PP) (4), as a function of UVC fluence in 3D human skin constructs immediately after exposure using the immunohistochemical approach previously described (7)."

It's natural to ask the question, is that the right thing to measure? There is no reason to suspect that 222nm and 254nm light will cleave the same bonds, so you might get a completely different set of dissociation products. Reference [7] has nothing to say on this subject (plus is citation incest) and in fact links back (as Reference [16]) to Reference [4], so that's the one. Except... it doesn't support this claim. At all. In fact it kind of suggests the opposite, that you can get pretty wide variation here depending on the incoming light: "In addition, we showed that the sequence distribution of CPDs induced by natural sunlight is very different from that induced by UVC (254 nm) at sequence positions specifically containing 5-methylcytosine bases."

So when I find crap like that in a paper that has a general air of puffery (as one, regrettably, must often take on these days in order to secure funding), I get really damn suspicious. I am not claiming anything is wrong, or that any claims are false. I am simply saying that the provided evidence is not sufficient to establish at least one of the paper's claims, and the authors are not forthright about it.

You could build a shade for the light or put it in some ventilation system or air purifier so that only airborne particles get killed.

That's a standard thing you can add to air handlers. We have UV-C bulbs in our own air handler units upstairs in the attic. They're expensive, though.

They have a diagram explaining the theory of why this is skin safe (doesn't penetrate the outer skin layer). But I see no reasoning as to why this is eye-safe. I would expect that the cornea is more fragile than the outer layer of dead skin.

One nice upside of using this in-situ is that it cleans surfaces just as much as it cleans the air. So just using this in the ducts / air filters is not as effective.

As per this article: https://www.nature.com/articles/s41598-020-67211-2

> ... far-UVC light has a range in biological materials of less than a few micrometers, and thus it cannot reach living human cells in the skin or eyes, being absorbed in the skin stratum corneum or the ocular tear layer.

The ocular tear layer, according to 30s of googling, is just the wet layer over your eyes (the stuff that turns into tears when you produce to much of it). So the idea is that this is eye-safe because the radiation gets absorbed by the small layer of wetness on your eyes.

> They have a diagram explaining the theory of why this is skin safe (doesn't penetrate the outer skin layer). But I see no reasoning as to why this is eye-safe.

It's described why it is eye-safe in literally the same diagram.

Regarding availability and LEDs:

"All commercially available Far-UV 222nm lamps have excimer lamps at their core. Excimer lamps are a lighting technology that excite a gas using high voltage electric discharges. Different gas mixtures generate different frequencies of light. Far-UV 222nm light is produced by excimer lamps filled with a mixture of krypton (Kr) and chloride (Cl) gas (normally less than 3% chloride)."

From https://www.boeing.com/confident-travel/downloads/CAP-3_Disi... provided in alliao's comment.

I was able to find one 5W lamp priced at around $1000 and a 20W at $1700.

Damn. That’s… a bit spendy. How much light did they output in these experiments?

That's pricey. Are you sure you didn't buy:

https://en.wikipedia.org/wiki/Extreme_ultraviolet

Even if the lights are effective, I am skeptical enough of LED quality control that I don't exactly jump to trust that the ones I get aren't leaking out the side bands (off-color basically) and sending adjacent more harmful wavelengths into my eyes. Especially if those LEDs start to be sold on Ebay and come from who-knows-what factories (which there already are).

1) Doesn't an LED have only a single band gap, determined by its main materials, thus no "side bands"?

2) Even if other wavelengths are produced, they just need to be produced in lesser quantities than in say sunlight.

3) #2 will require regulation and enforcement, but so do numerous other consumer devices - did you worry about your CFL leaking mercury?

1. Not if it relies on phosphors or dopants to achieve the desired emission profile.

2. I don't think that the standard for a safe environment at home or at work is that you are exposed to the wavelengths and intensities equal to direct sunlight?

The lamps aren't LED and you can't get to UV-C wavelengths in LEDs. Also 222nm is deep into the DNA damage spectrum so they aren't safe for living organisms anyway.

222nm is pretty rare, most are 253nm and many are just fake purple LEDs

but this is looking promising, boeing have an interesting article on it too I particularly love the toilet solution

https://www.boeing.com/confident-travel/downloads/CAP-3_Disi...

I’d guess it wouldn’t be too hard to tune manufacturing for lights for that if 253 is already common.

If we're talking about LED lights I don't think it's that simple. Wavelengths produced are related to the emission spectra of the elements which make up the diode junction. If I'm remembering my highschool physics correctly.

LED would be ideal, but right now I don’t care about the specifics and just want them to go into mass production.

Exactly. It's not a matter of 'tuning'. This is why it took so long to get blue LEDs.

Although there are a lot of new options these days, like Quantum Dots. If I'm not mistaken quantum dots can only convert the light to longer wavelengths though (so lower frequencies).

Yeah, tuning was the wrong word. But they already exist commercially. I just want them To be cheaper and more wide spread.

FDA article "UV Lights and Lamps: Ultraviolet-C Radiation, Disinfection, and Coronavirus" [https://www.fda.gov/medical-devices/coronavirus-covid-19-and...]

Nature: "Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses" (2020) PDF [https://www.nature.com/articles/s41598-020-67211-2.pdf]

Before you rush out and install powerful UV everywhere, think about the chemistry, and if you're chemistry topped out at Chem 101, maybe get an actual aerosol chemist.

"Unintended Consequences of Air Cleaning Chemistry" https://pubs.acs.org/doi/10.1021/acs.est.1c02582

I want one in my house.

Link to the actual study. https://www.nature.com/articles/s41598-022-08462-z

Me too - I have an air filter (noise/replacing it) but I rather this. Do you know where I can get one?? Figure it'd be easy to get

Wouldn't an open lamp severely degrade all kinds of paints and materials that aren't meant to be exposed to UV light? Or does the mechanism that supposedly makes the shorter wavelength safe for human skin cells apply to all materials?

Yeah be safer for many kinds of materials, it should, but I’m not sure what the thresholds for those materials are specifically.

I’m not that worried about random bacteria and microbes, people are covered in them. As long as it isn’t too much, we don’t need our buildings to be 100% sterile, except in certain locations like a Hospital. Mould, micro plastics, pm 2.5, microfibres, car pollution seem far more concerning, and we need to do something about those.

Every hospital needs these in every room ASAP.

Wasn’t there another issue with UV light disinfection where it creates ozone or something?

Yup, looks like

“ The Ultraviolet spectrum has four wavelengths, (see illustration below), labeled: UV-A (400 to 315 nm); UV-B (315 to 280 nm); very high energy and destructive UV-C (280 to 200 nm); and Vacuum UV (200 to 100 nm). Only this last wavelength, Vacuum UV, is capable of producing ozone.”

https://uvresources.com/the-ultraviolet-germicidal-irradiati...

Don’t know much about it though.

Not in significant quantities. Another study also using Far-UV excimer lamps [1] measured levels of less than 0.005 ppm, which is far below the 0.05 ppm maximum allowed by the FDA for medical devices [2].

[1] https://www.nature.com/articles/s41598-018-21058-w [2] https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-...

Just being a factor of ten away from being "dangerous", is not exactly what i would call "far"

I guess it’s no surprise that a shorter wavelength kills more stuff.

That said, I’m not super convinced that it’s safe, if it’s not something we normally have in our environment… the stuff being killed might be you.

I wonder if turning it on for five minutes every half hour or so would be a good compromise risk-wise (assuming it's more dangerous than the article wants to believe).

No, I’m pretty sure it’s that shorter wavelengths kill less stuff because it can penetrate less. My understanding is this research is about finding crossover points where it’s still deadly to microorganisms, but safe for more complex organisms.

Put it inside duct work

Yup, you don’t need to worry about tuning the UV. Just stick broad spectrum UV (excluding the 100-200nm only) in the duct work.

Is this uncommon? I had UV disinfectant bulbs installed as part of my HVAC installation in my house, seemed pretty common.

In new installations, but I think it’s only been common for less than a decade. All older systems will not have them unless they were specifically added.

Two challenges with making this work well. 1) Not destroying plastic and rubber components exposed to the light. 2) Ensuring whatever is passing through the light receives enough exposure. Often they're better at keeping evaporator coils clean than cleaning the air.

Oh? It makes sense, but I hadn't heard that. Have your read about that somewhere?

I'd be worried about my eyes even more than my skin tbh..

It may very well be safe but I'll need more convincing than "yeah your dead skin cells will protect you, don't worry about it bro".

The idea is apparently that the wet layer on your eyes is enough to protect your cornea.

See my comment here for sourcing: https://news.ycombinator.com/item?id=30829785

Hmmm so if I don't blink for too long I expose it?

I don't know, I'm not worried about corona anymore but much more about this :)

I have a rather serious photosensitivity disorder, so this sort of thing is vaguely terrifying.

When I see something like this I have to ask "if these people had come up with this a decade ago, why did it take them two years into a global pandemic to actually try it?".

Probably the same discoverability problem music, movies and apps suffer.

Can you elaborate? I mean, this is the people who came up with the idea, not some end user.

I mean an academic is inherently going to be cautious about putting forth something like this until they are throughly convinced from a public health perspective.

But from an outside perspective there are likely plenty of lower stakes ways to take advantage of this.

The example that occurs to me over was seeing UV disinfectants for tableware in restaurants 20 years ago in South Korea.

Just look at how the medical orthodoxy has behaved: first solving the wrong problem by putting emphasis on skin contact and droplet spread. Vague messaging about masking. Little messaging about ventilation. And now denial and downplaying about long COVID.

Scientific answers were there, but our institutions preferred to normalize their beliefs into their preexisting comfort zone and dismiss anything else with a "cool story bro". They only seem to learn after the blood has been spilled.

> Vague messaging about masking.

It wasn't vague. The WHO, CDC and the US Surgeon General were clear, explicit and wrong.

> The surgeon general has a message for people who want to run out and stockpile masks to combat the coronavirus – don't.

> "Seriously people - STOP BUYING MASKS!" Surgeon General Jerome Adams tweeted. "They are NOT effective in preventing general public from catching #Coronavirus, but if healthcare providers can’t get them to care for sick patients, it puts them and our communities at risk!"

https://www.jacksonville.com/story/news/healthcare/2020/03/0...

CDC does not currently recommend the use of facemasks to help prevent novel #coronavirus. Take everyday preventive actions, like staying home when you are sick and washing hands with soap and water, to help slow the spread of respiratory illness. https://twitter.com/cdcgov/status/1233134710638825473

Masks should not be worn by healthy people to prevent respiratory infection; there is no evidence that wearing masks prevents healthy people from getting sick and masks can be in short supply and unavailable for people who need them. https://twitter.com/jama_current/status/1235399635948142593

by admitting it's airborne I suspect it is a major upheaval on scope due to responsibilities of employers providing a safe working space.. hence the reluctance. it's too bad, we have careerest in every discipline, and somehow people in tenured positions didn't have the projection they needed to overcome all the noise.

Reading the article as most university press releases should be, this looks like a grab for some of the government money to 'explain away' the current covid situation and mindset. Just think, if this was cost-effective/safe/efficient/didn't-have-side-effect-X-such-as-breaking-down-plastics we'd likely be using it already...

Edit to preface: Forgive the potentially naive question but -what happens when some form of bacteria (or something) evolves in a way that renders it hardy enough to survive far-uvc? The article mentioned it's ability to destroy superbugs..just wondering if any thought has been given to unintended side effects like this.

I mean that’s like considering the ability for an organism to survive bleach. It’s not impossible, but my understanding is would be as difficult as building trinary /fuzzy logic CPUs. Basically reinventing it from the ground up.

It’s hard to evolve against instant death. When the atomic level chemistry/physics is against you, you’re fighting a losing battle.

If I read correctly, the study confirmed it was effective against airborne Staph. Not covid, although the latter is the one I thought of first. Wonder if it would be hard to get the same research study approved to test covid?

From the article:

> “This microbe was chosen because it is slightly less sensitive to far-UVC light than coronaviruses, providing the researchers with an appropriately conservative model”

This makes me think it would be effective against coronaviruses as well.

Do it once per room, at night with a mobile unit. Does it reduce risk to zero? No, but it resets the risk to a consistent floor, every day.

Others have done the "inside HVAC, its been sold for decades" thing already.

How many kilowatts of light is required to have this effect?

If it's a kilowatt per room, then humans simply don't have enough electricity production to deploy this widely.

Doesn't this end up destroying plastics and producing ozone and various other gasses from broken down molecules from everything in the room?

Sounds like a great thing to add to operating rooms and generally in high risk (with known antibiotic resistant bacteria infestation) hospitals.

If this is safe because of a layer of dead skin, I am not sure its a good idea to put this in operating rooms where they may have exposed inner flesh.

Imagine having a sunburn, but on your intestines.

Having (indirectly) lost a grandfather to complications following an infection during hip surgery, I think it’s at least worth looking into. So many people die because hospitals can’t prevent infections.

Why not radiate the room very strongly for a few minutes before surgery?

If the UV light kills 98% of microbes, what happens with the remaining 2% UV-resistant microbes, are they now the fittest?

Is there some fundamental reason that UV-C lamps have to be so expensive? Or is it a lack of demand problem?

They have a perception as specialist/medical so premium is the order of the day.

The prior lamps were heavy and inefficient. Newer LEDs are preferred but they are not made by that many companies, or until recently anyway. And many of the new entrants have crap longevity. Furthermore, sourcing issues compounded over COVID.

There are also unique design challenges mechanically for UVC. Just some of which are efficacy is inversely proportional to distance and time, and you need 100% line of sight to have any effect at all...

UVC lamps require exotic UV-transparent glasses. Soda-lime glass won't pass UV.

Why not just put the UV lights in the air ducts instead of point them at people?

I want to see refrigerators with this built in as well!

You can buy small ozone generators off aliexpress for your fridge if you're paranoid about germs. Then again you may also be paranoid about ozone since it's fairly nasty stuff.

Yeah, that seems waay worse.

I’m just thinking it would help food keep for longer. I’m not worried about germs in particular.

Ozone destroys rubber. I learned that the hard way trying to rid some soccer equipment of stink.

I kind of wonder if COVID-19 is a blessing in disguise. Something to kick the world in the pants and prepare for much worse diseases, whether man-made or natural. Will technology like better air treatment, MRNA vaccines, and better emergency preparedness save our butts some day?

Probably not, but it is nice to think that there is some silver lining.

222 nm?? No way jose. Free radicals don't just stay where you generate them. Even if the UV dose is minimal below a few layers of cells, it doesn't mean that radical damage does not reach live epidermal layers. Just using ventilation is a lot safer and has no real downsides.

> as safe as outdoors

Ah, forgot about Covid. I'm in Bucharest, and "as safe as outdoors" is pure masochism. Kids, stay away from corruption and incompetence, it gives cancer and lots of other stuff as well.

Isn't an air exchanger better?

According to the article, it is not:

"The efficacy of different approaches to reducing indoor virus levels is usually measured in terms of equivalent air changes per hour. In this study, far-UVC lamps produced the equivalent of 184 equivalent air exchanges per hour. This surpasses any other approach to disinfecting occupied indoor spaces, where five to 20 equivalent air changes per hour is the best that can be achieved practically."

For a better understanding, 184 exchanges per hour would mean one exchange per 19 to 20 seconds on average. For a room 5m wide, that would be a windspeed of 0.25m/s if one actually, physically exchanged the air in the room. That would be almost (or maybe already) perceptible.

Not even close. This would dramatically improve air quality (infection wise) in all situations.

I think that they are ignoring other factors.

It is better, because it doesn't create interesting chemistry. There are all sorts of products produced from normal pollutants and cleaning agents (sodium hypochlorite) with the extra energy from UV.

I couldn't stop thinking of zombies while reading this.

In Dying Light, ultraviolet light wards off the zombies.

If we assume that a) the imminent singularity/zombie apocalypse of modern reality will be preceded by infectious airborne viruses, and b) this new UV light has protective/cleansing effects that "reduce the level of indoor airborne microbes by more than 98%", c) that "that far-UVC light can kill the COVID virus, other human coronaviruses, influenza, and drug-resistant bacteria", then hey presto: we've got a potential counter-weapon that can be modified to work against the zombie apocalypse.

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