You are not an expert on optical safety and should not make sweeping, generalized statements as though you were.
I am an optical engineer, but don't specialize in eye-safe studies, and I wouldn't dare make a statement without consulting safety guidelines. The eye's sensitivity to wavelengths is exponentially variable, and very specific about some cutoffs - moreso than most biological phenomena, because the limiting factors are bandgaps of molecules, not cell structures.
I mean, UV light is carcinogenic, and environments that are way too clean, are fine for surgery or manufacturing semiconductors, but for most humans (specially children) they can be counter-productive.
The immune system needs something to train on and fight, otherwise you end up with autoimmune diseases and all sorts of crap.
We're essentially walking ecosystems that can easily be imbalanced.
Yes, you can point this specific UV wavelength at your skin and be fine. People have done extensive animal trials and it is not carcinogenic. Many people have been exposed to a lot of far UVC and nothing bad has happened to them.
Looking right at it might not be good for your eyes.
I feel confident for myself that far UVC is safe.
However, the environments I'd want to use this in are those where many people are gathered. I am not sure whether it is respectful/socially good to use this in those situations (given that far UVC products are not subject to any special regulatory review).
Edit for some additional thoughts:
How does this compare to a air filter?
Pros of UV:
- You are helping support R&D for this very important technology
- Even this Aerolamp DevKit is going to be more cost effective at addressing certain pathogens which are highly susceptible to UV, such as COVID. My guesstimate is that the highest capacity/$ off the shelf air purifier you can buy (https://www.cleanairkits.com/products/brisk-box-ultra-black) has about a third to half of the COVID-removing capacity/$ vs. the Aerolamp DevKit. Ditto for energy efficiency.
- Less maintenance vs. an air filter
- Quietest option
Cons of UV:
- Less energy and cost effective at addressing other microbes, particularly mold
- No ability to address dust, another very important air quality issue
The results of the study showed that far-UVC irradiation causes significant color degradation (∆E00 >5) in all the polymeric materials tested, after 290 J/cm2 radiant exposure. In addition, significant changes in mechanical properties were observed when evaluating elasticity modulus, elongation at ultimate strength, elongation at break, and tensile strength. A particularly large decrease in elongation at break (up to 26%) was observed in fiber-reinforced composite materials.
Is there anything that suggests this will turn out okay?
I don't think "stop using polymers in any place where far-uvc may exist" would fly. So it's cool that we've made something that isn't going to hurt humans, but if it destroys the stuff humans depend on, not sure that works either?
I also don't think the world is going to move to UV-stable polymers for everything just to make far-UVC work (in some cases this isn't even possible). We almost always just make things more UV-resistant instead of UV-stable.
I'm confused by the handwaving away of the ozone production. It's well established that ozone is toxic. If these are producing it - and it seems to be agreed upon that they are - that's an obvious issue. The suggestion that "you can just filter it with mechanical air filters (activated carbon)" seems strange because you can just filter viruses with mechanical air filters in that case...
I'm a big fan on the idea of improving air quality/reducing viral load in air to improve health. But I'd really prefer to see more of a push towards the "effective quiet (currently DIY) mechanical air filtration systems" the article links to then a technology with obvious and poorly quantified health risks.
Old-school UVC lights do produce ozone, and it needs to be taken care of.
Newer lights (might) use LEDs that do not produce ozone. I only use LED uvc lights. Also, and this is key: DO NOT look at the uvc light. It can damage your eyes. It is safe for your skin, but it is not safe to look at.
I've built 12V mercury vapor UV-C (254nm) lights for fluorescent mineral hunting, and that wavelength is quite harmful, requiring skin and eye protection. Mercury vapor lamps produce a spectrum of wavelengths, also in the visible spectrum, which gets filtered out since it distracts.
According to this [1] article, the 222nm range is safe for exposure, but the Krypton-Chloride bulb in the far-UVC lamp does also produce harmful wavelengths (256nm), therefore a filter is absolutely necessary. Thankfully simple plastics should work fine for that.
I would still be extremely careful deploying these lights in occupied spaces.
Edit: Come to think of it, filtering the harmful UVC (256nm) from KrCl excimer lamps with acrylic would probably also block the far-UVC. Which makes me wonder what material the filter is. Regular glass stops UVC, which is why UVC lamps are usually quartz or special glass formulations.
"What really needs to be understood is that an unfiltered 222nm Far-UV peak from any KrCl excimer lamp emits a wide band of wavelengths starting at 200nm, past the human safe zone of less than 230nm, all the way to the end of the UVC spectrum at 280nm -- with a very worrisome second harmonic peak at 256nm."
"the 222nm excimer lamp's second harmonic peak at 256nm exclusive to KrCl Far-UVC lights should be treated no different than the well-established carcinogenic hazards involved when using 254nm mercury-line UVC germicidal bulbs."
Of all the lessons society failed to learn from 2020, the importance of clean air is perhaps the most disappointing.
I wear N95 masks on local trains, long distance trains, planes, buses (most of the time), and movie theaters when busy. The few times I haven’t, in particular local train (unfortunately, lots of unhealthy people) and Amtrak, I have gotten sick - strep and covid. Being sick is in some ways not a big deal, but is serious enough I will keep wearing the masks forever. I get sick far less often than my non mask wearing peers.
The tragedy is that the people operating these services - and schools and hospitals - should have installed filters and UV lamps to make this less unnecessary. At least planes have air circulation, the Amtrak trains are an absolute disaster.
Flu is spreading like wildfire right now. With the advent of these and other technologies, that is essentially an opt-in choice society is making. Totally unnecessary. You don’t have to stop many flu cases before a lamp pays for itself.
> At $500 this is out of (my) Christmas gift range, but I think we're now at the point where dances, churches, offices, rationalist group houses, schools, etc. should consider them.
One of the things in that list gives this away as something you'd see on HN.
I looked it up and Far-UVC (typically 222 nm) seems safe-ish. But how do you confirm it's not outputting 254 nm or other wavelengths in the UVA/B range? Seems likely to happen with sloppy production of sources. You really have to trust the filter on the light or verify the frequency somehow.
Kr-Cl excimer lamps (the only cost effective UVC options currently available, and only manufactured via Ushio) have 2 big drawbacks:
1. Very low efficiency ($/watt and lux/watt) compared to UVA/UVB, such that cleaning a conference room between meetings, for example, results in unacceptable dead time compared to normal UV cleaning.
2. 222nm excimer lamps are a known cancer risk (official as of 2022, if I recall correctly), where the issue is that safety limits (in mW/cm^2 per 8 hour day) are based on theoretical skin absorption over a standard workday given a constant dose. Kr-Cl excimers do not produce a continuous illumination, and this intrinsic characteristic worsens with heat load. Transdermal effects are mediated via hair follicles, and shaved skin permits the greatest dose.
Even if you ignore practical safety concerns and take 1950's guidance as gospel, the time to neutralize covid via 222nm will exceed 60 seconds if the target is at the same distance a person would need to be for allowable safety.
tl;dr just put traditional UV in your hvac ductwork and skip on 222nm.
My guess is if we don't get a better vaccine, the COVID issue will probably be mostly or partially solved when 222nm UV-C LEDs become relatively efficient and low cost. At that point they will be mandated in public places.
This isn't (entirely) new. I did the electronics design for this lamp: https://www.fridotechnologies.com (nb: not affiliated any more, no stake in the business, just a freelancer).
The modules and emitters themselves are still relatively expensive - $200+ - but can be bought from China if you want to DIY a solution.
It's worth noting that the premise of the article- that low cost Far-UVC could not easily be purchased before the Aerolamp, is false.
While AeroLamp has put a proprietary Ushio emitter in a 3D printed enclosure as a sort of reference model to encourage the use of Ushio components, third party tested Far-UVC has been sold for several years now by Nukit222.com at a fraction of the price of any competitor.
Our approach is somewhat different. We use no IP-encumbered components, all parts that can be purchased from any of a dozen Shenzhen factories, we put the product firmly into the Gongkai ecosystem (https://www.bunniestudios.com/blog/2014/from-gongkai-to-open...) without being at the whim of a single high-cost proprietary central component the manufacturer can reprice at anytime.
By focusing on non-IP-encumbered designs that are basically shanzhai-able-"Temu friendly", and then validating the market for those products, you virtually guarantee it will be picked up, copied and improved upon- meaning lower costs and wider distribution.
If you want to make a fit-for-purpose product, faster, cheaper and at larger scale than the Shenzhen Hardware ecosystem iterating at Shenzhen speed with shanzhai- best of luck to you.
The central remaining issue is safety and efficacy, which is why we post all our third party lab tests, for all our products, for download on the sales page. Ozone output, pathogen chamber tests, full spectral assay for safety and power output, UL CE etc. We were the first company to do this, and push for all companies to do the same.
I am not convinced a single lamp placed over the dining table would provide sufficient irradiance to inactivate viruses and other pathogens in the large room. Consider having an infected individual sneeze or cough at the table. The expiration jet would spread so rapidly. This lamp is like a tiny flashlight placed above the dining table. Furthermore, far UV gets absorbed by oxygen in the air. The net irradiance of far uv is worse than 254 nm at a fixed distance from two equivalent (in power and form) sources.
The lamp would be effective if you were able to quickly circulate the air in the room past the lamp.
Yeah, what responsibly deployed far-UV is definitely not is an instant kill beam that immediately inactivates exhaled pathogens. I estimate it takes 100 mW of far-UV about 5 minutes to inactivate 90% of the flu/covid in a 250 sqft room (10 minutes to get to 99%), assuming the air is well-mixed. Far-UV should be thought of as a super-powerful quiet air filter more than anything else--it prevents infectious aerosols from building up in a space, which can matter a lot. You don't necessarily immediately get infected just because someone infected coughed near you--you might only get infected if you spend a long time near them, sharing their air. Continuously cleaning the air prevents these kinds of infections, and can make the infections that do still happen less severe.
You're totally right that circulating the air is important though! Definitely don't use far-UV in totally still air. But you don't necessarily need a LOT of air movement to achieve "good" mixing. Often just an air-change or so of ventilation is enough--just think about what would happen if you started smoking indoors. The smoke would be ~everywhere pretty fast.
The oxygen absorption at 222nm is not significant however--it's enough to produce a bit of ozone (less than you'd get from just opening a window), but not enough to actually absorb a significant amount of radiation. 222nm lamps are generally less powerful than 254nm lamps anyway, but because 254nm is much less safe, those systems have to be deployed in ways that often reduce their efficacy--in special louvred fixtures that kill most of their output or in portable units/ducts that constrain their effectiveness.
Before buying something like this for my home, I'd need to know:
* Is it safe for babies and small children (whose thin skin and developing eyes might well be much more vulnerable to UVC)
* Is it actually safe for all adults regardless of skin type, colors, dermatologic conditions, or was it only tested on a few healthy college students of one particular ethnicity;
* Does it accelerate degradation of household items, plastics, fabrics, books, and paint; and if so, by how much
24 comments
[ 3.3 ms ] story [ 49.0 ms ] threadI am an optical engineer, but don't specialize in eye-safe studies, and I wouldn't dare make a statement without consulting safety guidelines. The eye's sensitivity to wavelengths is exponentially variable, and very specific about some cutoffs - moreso than most biological phenomena, because the limiting factors are bandgaps of molecules, not cell structures.
(Like a reef tank sterilizer)
I mean, UV light is carcinogenic, and environments that are way too clean, are fine for surgery or manufacturing semiconductors, but for most humans (specially children) they can be counter-productive.
The immune system needs something to train on and fight, otherwise you end up with autoimmune diseases and all sorts of crap.
We're essentially walking ecosystems that can easily be imbalanced.
Looking right at it might not be good for your eyes.
I feel confident for myself that far UVC is safe.
However, the environments I'd want to use this in are those where many people are gathered. I am not sure whether it is respectful/socially good to use this in those situations (given that far UVC products are not subject to any special regulatory review).
Edit for some additional thoughts:
How does this compare to a air filter?
Pros of UV:
- You are helping support R&D for this very important technology
- Even this Aerolamp DevKit is going to be more cost effective at addressing certain pathogens which are highly susceptible to UV, such as COVID. My guesstimate is that the highest capacity/$ off the shelf air purifier you can buy (https://www.cleanairkits.com/products/brisk-box-ultra-black) has about a third to half of the COVID-removing capacity/$ vs. the Aerolamp DevKit. Ditto for energy efficiency.
- Less maintenance vs. an air filter
- Quietest option
Cons of UV:
- Less energy and cost effective at addressing other microbes, particularly mold
- No ability to address dust, another very important air quality issue
- May make others feel uncomfortable
The only studies i can find suggest this is an issue. For example:
https://www.mdpi.com/2076-3417/13/7/4141
Is there anything that suggests this will turn out okay?I don't think "stop using polymers in any place where far-uvc may exist" would fly. So it's cool that we've made something that isn't going to hurt humans, but if it destroys the stuff humans depend on, not sure that works either?
I also don't think the world is going to move to UV-stable polymers for everything just to make far-UVC work (in some cases this isn't even possible). We almost always just make things more UV-resistant instead of UV-stable.
I'm a big fan on the idea of improving air quality/reducing viral load in air to improve health. But I'd really prefer to see more of a push towards the "effective quiet (currently DIY) mechanical air filtration systems" the article links to then a technology with obvious and poorly quantified health risks.
Newer lights (might) use LEDs that do not produce ozone. I only use LED uvc lights. Also, and this is key: DO NOT look at the uvc light. It can damage your eyes. It is safe for your skin, but it is not safe to look at.
According to this [1] article, the 222nm range is safe for exposure, but the Krypton-Chloride bulb in the far-UVC lamp does also produce harmful wavelengths (256nm), therefore a filter is absolutely necessary. Thankfully simple plastics should work fine for that.
I would still be extremely careful deploying these lights in occupied spaces.
Edit: Come to think of it, filtering the harmful UVC (256nm) from KrCl excimer lamps with acrylic would probably also block the far-UVC. Which makes me wonder what material the filter is. Regular glass stops UVC, which is why UVC lamps are usually quartz or special glass formulations.
"What really needs to be understood is that an unfiltered 222nm Far-UV peak from any KrCl excimer lamp emits a wide band of wavelengths starting at 200nm, past the human safe zone of less than 230nm, all the way to the end of the UVC spectrum at 280nm -- with a very worrisome second harmonic peak at 256nm."
"the 222nm excimer lamp's second harmonic peak at 256nm exclusive to KrCl Far-UVC lights should be treated no different than the well-established carcinogenic hazards involved when using 254nm mercury-line UVC germicidal bulbs."
[1] https://www.prweb.com/releases/222-nm-far-uvc-cancer-risk-wi...
I wear N95 masks on local trains, long distance trains, planes, buses (most of the time), and movie theaters when busy. The few times I haven’t, in particular local train (unfortunately, lots of unhealthy people) and Amtrak, I have gotten sick - strep and covid. Being sick is in some ways not a big deal, but is serious enough I will keep wearing the masks forever. I get sick far less often than my non mask wearing peers.
The tragedy is that the people operating these services - and schools and hospitals - should have installed filters and UV lamps to make this less unnecessary. At least planes have air circulation, the Amtrak trains are an absolute disaster.
Flu is spreading like wildfire right now. With the advent of these and other technologies, that is essentially an opt-in choice society is making. Totally unnecessary. You don’t have to stop many flu cases before a lamp pays for itself.
One of the things in that list gives this away as something you'd see on HN.
There are lot of fake ones out there. Especially ones with LEDs. Nobody has a 222nm LED with enough power for this yet.
Someone should make a simple tester. Something that's on the end of a stick, you hold it up near the ceiling, and it lights up:
- Green - enough 222nm light to be effective, not too much other UV.
- Red - too much other UV, light is dangerous.
- Yellow - only "homeopathic" levels of 222nm, ineffective.
You can buy NBS-traceable UV meters, and even a spectrometer, but they're expensive.
[1] https://cybernightmarket.com/products/nukit-lantern-far-uvc-...
1. Very low efficiency ($/watt and lux/watt) compared to UVA/UVB, such that cleaning a conference room between meetings, for example, results in unacceptable dead time compared to normal UV cleaning.
2. 222nm excimer lamps are a known cancer risk (official as of 2022, if I recall correctly), where the issue is that safety limits (in mW/cm^2 per 8 hour day) are based on theoretical skin absorption over a standard workday given a constant dose. Kr-Cl excimers do not produce a continuous illumination, and this intrinsic characteristic worsens with heat load. Transdermal effects are mediated via hair follicles, and shaved skin permits the greatest dose.
Even if you ignore practical safety concerns and take 1950's guidance as gospel, the time to neutralize covid via 222nm will exceed 60 seconds if the target is at the same distance a person would need to be for allowable safety.
tl;dr just put traditional UV in your hvac ductwork and skip on 222nm.
The modules and emitters themselves are still relatively expensive - $200+ - but can be bought from China if you want to DIY a solution.
While AeroLamp has put a proprietary Ushio emitter in a 3D printed enclosure as a sort of reference model to encourage the use of Ushio components, third party tested Far-UVC has been sold for several years now by Nukit222.com at a fraction of the price of any competitor.
Our approach is somewhat different. We use no IP-encumbered components, all parts that can be purchased from any of a dozen Shenzhen factories, we put the product firmly into the Gongkai ecosystem (https://www.bunniestudios.com/blog/2014/from-gongkai-to-open...) without being at the whim of a single high-cost proprietary central component the manufacturer can reprice at anytime.
By focusing on non-IP-encumbered designs that are basically shanzhai-able-"Temu friendly", and then validating the market for those products, you virtually guarantee it will be picked up, copied and improved upon- meaning lower costs and wider distribution.
If you want to make a fit-for-purpose product, faster, cheaper and at larger scale than the Shenzhen Hardware ecosystem iterating at Shenzhen speed with shanzhai- best of luck to you.
The central remaining issue is safety and efficacy, which is why we post all our third party lab tests, for all our products, for download on the sales page. Ozone output, pathogen chamber tests, full spectral assay for safety and power output, UL CE etc. We were the first company to do this, and push for all companies to do the same.
The lamp would be effective if you were able to quickly circulate the air in the room past the lamp.
You're totally right that circulating the air is important though! Definitely don't use far-UV in totally still air. But you don't necessarily need a LOT of air movement to achieve "good" mixing. Often just an air-change or so of ventilation is enough--just think about what would happen if you started smoking indoors. The smoke would be ~everywhere pretty fast.
The oxygen absorption at 222nm is not significant however--it's enough to produce a bit of ozone (less than you'd get from just opening a window), but not enough to actually absorb a significant amount of radiation. 222nm lamps are generally less powerful than 254nm lamps anyway, but because 254nm is much less safe, those systems have to be deployed in ways that often reduce their efficacy--in special louvred fixtures that kill most of their output or in portable units/ducts that constrain their effectiveness.
222nm seems to be more effective per-photon at inactivating viruses than 254nm too: https://pubs.acs.org/doi/10.1021/acs.est.3c08675
* Is it safe for babies and small children (whose thin skin and developing eyes might well be much more vulnerable to UVC)
* Is it actually safe for all adults regardless of skin type, colors, dermatologic conditions, or was it only tested on a few healthy college students of one particular ethnicity;
* Does it accelerate degradation of household items, plastics, fabrics, books, and paint; and if so, by how much