I have worked on such systems at Signify: There are numerous barriers to wider adoption except for very high risk situations. For instance: there have yet to be lawsuits to determine the risk of exposing people to UV. As you see in the comments below, any "UV" is considered dangerous by people not aware of the biological effects of various wavelenghts.
Besides this, excimer lamps have a low expected lifetime, of both the light source as well as the filter due to the high energy in the UV photons. This makes replacement (and maintenance cost) a real risk. This could be remedied by similar wavelength LEDs from companies like CrystalIS but these are expensive and very low power (only work germicidal on a short distance).
Prof. Brenner at Columbia University has first foreseen applications of 222nm in operating rooms, to prevent infection during surgery.
On the whole, it would need significant investment in both research, certification and risk analysis for this to become commercially viable, so while some of the technology is there, the market demand so far just is not -- post-pandemic.
Is there any reason why they can't just be installed inside air purifiers/ventilation?
Especially since you could probably get more mileage out of the same amount of light energy by forcing the air through a narrower passage, since only airborne particles are actually going to absorb any energy anyway, and air is mostly just empty air.
That solution is actually suggested in the article. However, that still leaves the cost issue mentioned by GP, and until that is solved, this will remain something for specialized applications (operating rooms) and maybe hypochondriac millionaires...
Yeah I saw a lamp for this and it had a proximity sensor to prevent overexposure. There's no way I'm buying a lamp that needs that to be safe. Especially if it's expensive and only lasts a year or two.
Depends on your HVAC system and the maintenance cost in your area. For me at 150€ per intervention it wouldn't make any sense, but I have heard some HVAC develop a smell and in that case, UV is likely to prevent it.
Mostly used to eliminate or reduce mould growth on the inverter? If HVAC is taking air in or blowing air out, there really wouldn't be a point disinfecting the air.
If it's re-circulating, it could reduce the spread of germs room to room as has been shown during the pandemic in elderly care facilities. That would be the only use-case I see.
they claim it would reduce growths on the coils but also eliminate mold and bacteria spores. Our system is a re-circulating system. One large intake in the center of the house and out flows in individual rooms.
The mould reduction is real, and could lenghten the maintenance intervals for cleaning. Not fully eliminate it though, it really only eliminates the parts the UV light reaches (so not the back, or any other part not exposed).
there are much simpler and more reliable ways to significantly reduce indoor air contaminents.
one is a building method that produces a "floating" slab floor, that has a small gap around most of the walls, and the underfloor space is vented upwards with a chimney, this creates a small but continious air current that removes most dust and other things in the air.
And then the simple expedient of useing radiant heat sources, that while not as lethal as UV, are
in fact quite deadly to bacteria and anything tiny with a high water content, but completly harmless to humans and ,animals,plants. Couple this with hard, smooth ,surfaces that are designed so that there no crevices or areas filth can acumulate, useing hard woods,glass,tile,metal,leather/vinyl l,high gloss paint,for surfaces. No cloth, no carpet.While not exactly cosy or friendly, it makes getting home that much nicer.
Cheap, reliable, low maintenence, implimentable at scale, now.
Your first paragraph is advocating for ventilation, which is great but there's been so much incentive to reduce building energy consumption (heating/cooling) that recirculating, filtration and other technologies have resulted in offices becoming almost sealed off. We are now moving towards more balanced models as people don't feel comfortable in such offices e.g. sick building syndrome.
No mention of ozone. The more directly dangerous 254nm UV light has the advantage that it doesn't create ozone.
Viruses and bacteria aren't the only bad things you don't want in your air. Ozone is thought to be a carcinogen in its own right and aggravate the health effects of particulate pollution. We want filtering and air circulation anyway, we don't want anything that makes it worse. The consumer electronics industry is all too willing to try to sell us things that make our problems worse, such as ultrasonic humidifiers, or ionizing air purifiers with special chambers for your aromatherapy oils, so it's best to be careful.
Could accumulate in an isolated room, but following normal building ventilation standards, really shouldn't be an issue as shown by Brenner in 2023: https://pubmed.ncbi.nlm.nih.gov/38037431/
article specificaly mentions rooms with poor ventilation. if you have proper ventilation, then you don't need this system in the first place, because you will get ouside air UV sterilised by the sun...
Interesting, but I use a much more powerful germicidal UV source. Because of the power requirements it uses a fusion energy source located ~150M km away. (sunlight in fresh air.)
In fairness to the article, ventilation was mentioned, but also quickly dismissed. The 60% efficiency figure quoted for ERV is also a bit on the low side for many contexts. And sure, ERV fans themselves use some power (say 50W) but that's about what you'd use in a decent size room with some UV lamps and a fan.
Seems like this has potential, but uv exposure is potentially problematic to humans, and definitely problematic to man surfaces and some plants.
Limiting the wavelength helps with humans, but adds a lot of cost.
It might be effective to have a box that draws in air (with a fan, most likely) and the UV source shines within. The inputs and outputs would need to have a few turns and have surface treatments to reduce the amount of uv ligh that can escape. You would have some fan noise though.
This is correct and such systems do exist, sometimes combined with sources of ions and HEPA filters. However if you're already drawing air out of the room, it's easier to just filter it with HEPA than dealing with the additional complexity of UV lights (deterioration, energy consumption, replacement).
It's a minor point, but it's interesting that they used having AC as a proxy for mechanical ventilation and conclude that it's rare in Europe. At least where I live (NL), mechanical ventilation is common - I think required in some situations - even though AC isn't. It's basically a fancy extractor fan that pumps air outside, so bringing fresh air in. That said, you'd need to reverse that flow to add filters.
Yes, few people have AC but almost everyone living in a semi recent place has mechanical ventilation in, at the very least, kitchen and bathroom, which thanks to physics renew the air of the entire falt/house.
Still risky, these typical Chinese devices don't come with a filter, so harmful wavelengths will still be present. The filter is actually the expensive part. Also, such a small component would need sufficient cooling as these operate at 4kV. I don't really see this here, so it makes me doubt these devices.
The germicidal effect is a function of the DNA being directly affected by the UV rays and breaking apart. Very few organisms exist that could adapt, this would require external shells, skin etc, not typically found in microorganisms.
> I think the microbes are still trying to figure this one out.
They mostly figured it out a couple billion years ago. Cyanobacteria oxidized Earth's surface until the atmosphere was flooded with molecular oxigen, that gets turned to ozone in the stratosphere, filtering most UV. Pretty large engineering feat for a bunch of microbes.
You are correct, however most of the harmful rays get filtered out in the upper atmosphere. Far-UV doesn't reach Earth, only UV-A and small amounts of UV-B (if the ozone layer is more or less intact that is!).
I also wonder about stuff like this. I think some things are just a bridge-too-far for organisms to evolve protections against. For instance, are we worried about using too much bleach? Or stepping on cockroaches?
There are radiotrophic fungi that thrive in Chernobyl, so I wouldn't hold too much hope for UV either. It probably won't be able to penetrate a decent biofilm.
Idiotic and massively overlooks/underestimates how complex biology is.
What about beneficial and neutral but important bacteria and viruses? "Air" is actually a complex soup of all types of things. This like applying HCl to a skin infection.
I doubt it would be a problem for the microbiome [1] but I would worry about the immune system. Would being inside in sterilized air all the time mean you can't go outside or into a forest without getting really sick?
[1] but who am I, it would still be worthwhile to check obviously
The underlying thought is that outside air (such as a forest) gets UV sterilized by the sun. So this would bring inside air up to the sterilization level of outside air.
I would consider it unlikely that airborne germs form a significant input to our microbiomes.
For example, the gut microbiome is in flux for about the first 3 years of life, and thereafter it's mostly only the relative abundances of different microbes that shift in response to diet, you need something like antibiotics or severe diarrhea to actually induce permanent changes (usually for the worse).
Compared to that, there really aren't many microbes in the air. For children, it could very possibly be bad, but even then I'd expect most of their microbial input to come from their parents, food, and surfaces. Which are already grossly deficient compared to old-school rural settings, but I'm not sure if germicidal UV would make it worse.
I have worked on such systems at Signify: There are numerous barriers to wider adoption except for very high risk situations. For instance: there have yet to be lawsuits to determine the risk of exposing people to UV. As you see in the comments below, any "UV" is considered dangerous by people not aware of the biological effects of various wavelenghts.
Besides this, excimer lamps have a low expected lifetime, of both the light source as well as the filter due to the high energy in the UV photons. This makes replacement (and maintenance cost) a real risk. This could be remedied by similar wavelength LEDs from companies like CrystalIS but these are expensive and very low power (only work germicidal on a short distance).
Prof. Brenner at Columbia University has first foreseen applications of 222nm in operating rooms, to prevent infection during surgery.
On the whole, it would need significant investment in both research, certification and risk analysis for this to become commercially viable, so while some of the technology is there, the market demand so far just is not -- post-pandemic.
Is there any reason why they can't just be installed inside air purifiers/ventilation?
Especially since you could probably get more mileage out of the same amount of light energy by forcing the air through a narrower passage, since only airborne particles are actually going to absorb any energy anyway, and air is mostly just empty air.
That solution is actually suggested in the article. However, that still leaves the cost issue mentioned by GP, and until that is solved, this will remain something for specialized applications (operating rooms) and maybe hypochondriac millionaires...
Yeah I saw a lamp for this and it had a proximity sensor to prevent overexposure. There's no way I'm buying a lamp that needs that to be safe. Especially if it's expensive and only lasts a year or two.
Every year our HVAC company tries to sell us UV lights for the HVAC system. They claim it's only about $1500 to install. Are these snake oil?
Depends on your HVAC system and the maintenance cost in your area. For me at 150€ per intervention it wouldn't make any sense, but I have heard some HVAC develop a smell and in that case, UV is likely to prevent it.
Mostly used to eliminate or reduce mould growth on the inverter? If HVAC is taking air in or blowing air out, there really wouldn't be a point disinfecting the air.
If it's re-circulating, it could reduce the spread of germs room to room as has been shown during the pandemic in elderly care facilities. That would be the only use-case I see.
they claim it would reduce growths on the coils but also eliminate mold and bacteria spores. Our system is a re-circulating system. One large intake in the center of the house and out flows in individual rooms.
The mould reduction is real, and could lenghten the maintenance intervals for cleaning. Not fully eliminate it though, it really only eliminates the parts the UV light reaches (so not the back, or any other part not exposed).
there are much simpler and more reliable ways to significantly reduce indoor air contaminents. one is a building method that produces a "floating" slab floor, that has a small gap around most of the walls, and the underfloor space is vented upwards with a chimney, this creates a small but continious air current that removes most dust and other things in the air.
And then the simple expedient of useing radiant heat sources, that while not as lethal as UV, are in fact quite deadly to bacteria and anything tiny with a high water content, but completly harmless to humans and ,animals,plants. Couple this with hard, smooth ,surfaces that are designed so that there no crevices or areas filth can acumulate, useing hard woods,glass,tile,metal,leather/vinyl l,high gloss paint,for surfaces. No cloth, no carpet.While not exactly cosy or friendly, it makes getting home that much nicer. Cheap, reliable, low maintenence, implimentable at scale, now.
Your first paragraph is advocating for ventilation, which is great but there's been so much incentive to reduce building energy consumption (heating/cooling) that recirculating, filtration and other technologies have resulted in offices becoming almost sealed off. We are now moving towards more balanced models as people don't feel comfortable in such offices e.g. sick building syndrome.
No mention of ozone. The more directly dangerous 254nm UV light has the advantage that it doesn't create ozone.
Viruses and bacteria aren't the only bad things you don't want in your air. Ozone is thought to be a carcinogen in its own right and aggravate the health effects of particulate pollution. We want filtering and air circulation anyway, we don't want anything that makes it worse. The consumer electronics industry is all too willing to try to sell us things that make our problems worse, such as ultrasonic humidifiers, or ionizing air purifiers with special chambers for your aromatherapy oils, so it's best to be careful.
Could accumulate in an isolated room, but following normal building ventilation standards, really shouldn't be an issue as shown by Brenner in 2023: https://pubmed.ncbi.nlm.nih.gov/38037431/
article specificaly mentions rooms with poor ventilation. if you have proper ventilation, then you don't need this system in the first place, because you will get ouside air UV sterilised by the sun...
Interesting, but I use a much more powerful germicidal UV source. Because of the power requirements it uses a fusion energy source located ~150M km away. (sunlight in fresh air.)
In fairness to the article, ventilation was mentioned, but also quickly dismissed. The 60% efficiency figure quoted for ERV is also a bit on the low side for many contexts. And sure, ERV fans themselves use some power (say 50W) but that's about what you'd use in a decent size room with some UV lamps and a fan.
Seems like this has potential, but uv exposure is potentially problematic to humans, and definitely problematic to man surfaces and some plants.
Limiting the wavelength helps with humans, but adds a lot of cost.
It might be effective to have a box that draws in air (with a fan, most likely) and the UV source shines within. The inputs and outputs would need to have a few turns and have surface treatments to reduce the amount of uv ligh that can escape. You would have some fan noise though.
This is correct and such systems do exist, sometimes combined with sources of ions and HEPA filters. However if you're already drawing air out of the room, it's easier to just filter it with HEPA than dealing with the additional complexity of UV lights (deterioration, energy consumption, replacement).
HEPA filters also have deterioration, energy consumption (pressure drop ain't free), and replacement.
HEPA is a mature technology with no big improvement curve, but UV treatment is seeing progress.
It's a minor point, but it's interesting that they used having AC as a proxy for mechanical ventilation and conclude that it's rare in Europe. At least where I live (NL), mechanical ventilation is common - I think required in some situations - even though AC isn't. It's basically a fancy extractor fan that pumps air outside, so bringing fresh air in. That said, you'd need to reverse that flow to add filters.
Yes, few people have AC but almost everyone living in a semi recent place has mechanical ventilation in, at the very least, kitchen and bathroom, which thanks to physics renew the air of the entire falt/house.
If only 222nm UV lamps didn't cost so much.[1]
[1] https://cybernightmarket.com/products/mini-far-uvc-lights-se...
Still risky, these typical Chinese devices don't come with a filter, so harmful wavelengths will still be present. The filter is actually the expensive part. Also, such a small component would need sufficient cooling as these operate at 4kV. I don't really see this here, so it makes me doubt these devices.
Wont micro-organisms quickly adapt and start producing UV resistant strains?
The germicidal effect is a function of the DNA being directly affected by the UV rays and breaking apart. Very few organisms exist that could adapt, this would require external shells, skin etc, not typically found in microorganisms.
Tardigrades and organisms ables to survive space by having more efficient DNA repair mechanisms.
Unlikely for most organism, true
There is a giant orb in the sky that emits UV and has for billions of years.
I think the microbes are still trying to figure this one out.
> I think the microbes are still trying to figure this one out.
They mostly figured it out a couple billion years ago. Cyanobacteria oxidized Earth's surface until the atmosphere was flooded with molecular oxigen, that gets turned to ozone in the stratosphere, filtering most UV. Pretty large engineering feat for a bunch of microbes.
You are correct, however most of the harmful rays get filtered out in the upper atmosphere. Far-UV doesn't reach Earth, only UV-A and small amounts of UV-B (if the ozone layer is more or less intact that is!).
I also wonder about stuff like this. I think some things are just a bridge-too-far for organisms to evolve protections against. For instance, are we worried about using too much bleach? Or stepping on cockroaches?
There are radiotrophic fungi that thrive in Chernobyl, so I wouldn't hold too much hope for UV either. It probably won't be able to penetrate a decent biofilm.
ASTRAL DID IT AGAIN!!!1
Idiotic and massively overlooks/underestimates how complex biology is.
What about beneficial and neutral but important bacteria and viruses? "Air" is actually a complex soup of all types of things. This like applying HCl to a skin infection.
I doubt it would be a problem for the microbiome [1] but I would worry about the immune system. Would being inside in sterilized air all the time mean you can't go outside or into a forest without getting really sick?
[1] but who am I, it would still be worthwhile to check obviously
The underlying thought is that outside air (such as a forest) gets UV sterilized by the sun. So this would bring inside air up to the sterilization level of outside air.
I would consider it unlikely that airborne germs form a significant input to our microbiomes.
For example, the gut microbiome is in flux for about the first 3 years of life, and thereafter it's mostly only the relative abundances of different microbes that shift in response to diet, you need something like antibiotics or severe diarrhea to actually induce permanent changes (usually for the worse).
Compared to that, there really aren't many microbes in the air. For children, it could very possibly be bad, but even then I'd expect most of their microbial input to come from their parents, food, and surfaces. Which are already grossly deficient compared to old-school rural settings, but I'm not sure if germicidal UV would make it worse.
Studying a building's microbiome is really a new field. What happens to people if offices become boxes of sterile air and -surfaces? We don't know.
> What about beneficial and neutral but important bacteria and viruses?
Such as what? There are some located in the gut, but pretty much everything else out there is in conflict with our immune system.
where are you getting this info?
almost every mucosal surface has commensal bacteria which can provide colonization resistance by other bacteria. lungs, skin, vagina, etc..
UV causes melanoma which is why we wear sunscreen.
too much UV all at once, you mean. melanoma is not common and face and arms - the regions which receive the most sunlight
a moderate amount of UV stimulates vitamin D production, suppresses inflammation, and turns on DNA repair pathways
This moderate amount of UV is enough to accelerate skin aging which is why we wear sunscreen.
The article explains this concern in the 3rd and 4th paragraph.
Wong UV wavelength range! 222nm is safe for humans [0]!
[0]: https://www.nature.com/articles/s41598-020-67211-2
Far UVC?