6 ms·

UV Devices Could Keep Indoor Air Free of Viruses

77 points by sohkamyung 4y ago

blincoln 4y ago
I'm a big fan of using UV for germicidal purposes, but I get extremely concerned when people propose using it in rooms where people are present, like the "just put it high up in a vaulted ceiling" approach discussed in the article. People can get eye damage from halogen lamps with cracked filters in school gymnasiums[1], and those ceilings are generally higher than you'd see in most other types of room. The potential to end up deploying something that ends up being another asbestos-type "oops, we gave an entire generation cataracts and skin cancer" situation really concerns me. I'd want to see either some very long term research indicating that it didn't happen with far-UV light at all, or that the lights were in fixtures that somehow completely prevented the people below from being exposed. [1] https://www.cdc.gov/mmwr/volumes/65/wr/mm6511a4.htm https://www.cdc.gov/mmwr/volumes/65/wr/mm6511a4.htm
Aperocky 4y ago
Bacterial heaven ensues.
joe_the_user 4y ago
I don't understand why there hasn't a lot of resources put into approaches like this.
- themitigating 4y ago
  Looks like researchers are looking into it "The technique works well, says William Bahnfleth, an architectural engineer at Pennsylvania State University in University Park who focuses on indoor air quality." Also the article notes there's a safety aspect
- Animats 4y ago
  It works, but it's hard to do. * The far-UV lamps cost way too much. * There are a sizable number of fake ones out there. * There aren't standards and inspection tools for this. A useful tool would be a UV detector on a stick. You touch it to the ceiling, and it reports on whether there's enough UV in the right wavelengths to kill viruses. The idea is to have emitters which radiate horizontally, with most of the UV up near the ceiling. You also need a handheld device which checks at eye level for excessive near UV. With both of those, you could quickly tell if a room had reliable virus protection.
  - joe_the_user 4y ago
    All that makes sense - for an ordinary product in an ordinary market. But this seems like something that could make a serious dent in the covid situation and so government mandates and money could flow and get these much more widely deployed with strong standards.
    - epicureanideal 4y ago
      Also possibly useful military applications. Heck, have the soldiers wear some goggles that have UV protection and just saturate the room in virus killing UV periodically if there’s a suspected biological attack. Although, why not just put this UV emitter in a big box that has some kind of light filter on it to keep the UV inside rather than worrying about top of the room and so on?
      - Animats 4y ago
        Because you have to push the air through the box with fans. If you can make the ceiling area a kill zone for viruses, ordinary convection effects will push all the air through it regularly.
  - NikkiA 4y ago
    Also, the UV light involved is very damaging to eyes (causing cataracts and macular degeneration), so it has to be kept entirely contained, yet have all/most of your breathable air pass through it somehow.
  - vigeek 4y ago
    They make these for hvac systems, mines installed in the air return, fully enclosed it works well. When the heat or AC isn't in use, I just run the hvac system fan.
- glenngillen 4y ago
  I know of at least one company that is deploying them: https://gangigermicidalsystems.com.au/ https://gangigermicidalsystems.com.au/
a1371 4y ago
When you talk to Indoor Air Quality (IAQ) most are uncomfortable with UV. Reason being that while you can get rid of viruses, you can also create volatile compounds. Our homes' air is like a soup of natural and synthetic chemicals. From your flooring wear to your decor off-gassing to cooking, there are elements in your air that may be safe as they are, but they can completely change when they hit something volatile like ozone (from cars). Subsequently there can be a chain reaction with other compounds, potentially causing particles in your air that are bad for your health. If you could see that with magical glasses it would seem as if there are fireworks happening in your air triggered by those volatile compounds. So while UV has clear benefits, the byproducts that the lab conditions usually don't catch, make the applications limited.
- bradknowles 4y ago
  Most quality whole-home HEPA air filters I know of are available with UV lights that can be added to the mix to further help reduce the viral load in the house. And excessive ozone production is specifically avoided. For those units, I don't think there's anything to be concerned about here, except the added cost of the UV lighting and what might happen if you (or a technician) were accidentally exposed to the UV lighting during maintenance of the equipment. IMO, you're going to have to provide some extraordinary evidence if you want to claim UV health risks beyond these two factors.
- wesapien 4y ago
  My uncle has ozone generators in his home. One of them is industrial strength and he only runs it when he is leaving his house for awhile. Does ozone produce by products? I vaguely recall hospitals used ozone to clean n95 masks.
  - colechristensen 4y ago
    Ozone itself is the main culprit.
  - yummypaint 4y ago
    I think it's pretty well established that ozone can interact unpredictabily, especially with chemically complex modern building materials. Here is one anecdotal example: https://www.reddit.com/r/homeowners/comments/d2rjsb/ozone_generator_left_a_bad_odor/ https://www.reddit.com/r/homeowners/comments/d2rjsb/ozone_ge... N95 masks actually seem like one of the few use cases that make sense, as their composition is well known and they can be easily enclosed. Even when ozone generators work as expected, they can take months to remove odors from spaces.
amluto 4y ago
Obligatory Derek Lowe link: https://www.science.org/content/blog-post/two-twenty-two https://www.science.org/content/blog-post/two-twenty-two
Scoundreller 4y ago
Would like to see what my mini office heater can do. The air it outputs is about 75C and I like to think that would kill any viruses, but I guess it depends on whether the split second at that temperature would kill it or not.
abdullahkhalids 4y ago
If this is used inside homes and offices, how does one train their immune system, which requires constant low level exposure to foreign entities?
- colechristensen 4y ago
  The problem is enclosed spaces build up pretty high levels of exposure you just don’t find in natural environments. There also tend to have much less of the harmless diversity that outside has.
  - beebeepka 4y ago
    Open doors and windows to create a current. Do it on a daily basis
    - Auracle 4y ago
      That’s not an option for most climates.
      - beebeepka 4y ago
        Care to elaborate? I would think it depends more on the type of building than anything else. Having wind helps tremendously, of course
        colechristensen 4y ago
        It’s 25 F outside right now :) not such a fan of ventilating now…
        beebeepka 4y ago
        -4c is nothing. In fact, it'll make the procedure easier. I do at -20c and below
        4y ago
kumarvvr 4y ago
Would they also degrade paintings, papers, photos, display devices etc?
- unglaublich 4y ago
  That's why the UV treatment is done in an enclosure through which air is vented.
nicodds 4y ago
I think mechanical ventilation (MV) is less risky and almost as effective in preventing spread of viruses. Probably, coupling MV with a boxed UV lamp (no UV radiation outside the box) would be more effective.
sberder 4y ago
I haven't seen one of the main arguments against UV efficiency in the context of an HVAC system. Most common UV solutions simply cannot clean at the speed the air goes through the systems in most buildings. When you have to maintain 6 air changes per hour, the UV solutions are simply not manageable. There are other limitations but that's the main issue as far as I can tell talking to facility managers.
- vigeek 4y ago
  This is what I have installed at my house, it works well.
- dtgriscom 4y ago
  A room, its occupants and its HVAC is a steady state system, with people emitting virus particles and the HVAC system removing it. The goal is to have the HVAC system remove virus particles quickly enough so that the average particle density is low. You don't need the air coming out of the vent to be completely aseptic; you just need to remove a significant amount of the virus on each pass.
ciconia 4y ago
I find the obsession with having a sterile environment ridiculous. Our bodies themselves are teeming with microbes and viruses, actually our bodies contain more of them than our own human cells. They play an important role in our digestive system, as well as our metabolism and also keeping our immune system on its guard. What needs to be done is not to eliminate those actors, but rather to make our bodies resilient to potentiel pathogens.
- Gigachad 4y ago
  For viruses sure, but other things like air filters make sense. Nothing good comes from breathing combustion engine exhaust or gas stove combustion byproducts. If you live anywhere near a coal mine or power plant you are also getting a good dose of radioactive dust although I’m not sure a hepa filter is good enough there.
- goodpoint 4y ago
  > make our bodies resilient to potentiel pathogens How? Magic?
  - refurb 4y ago
    Immune system? Some might call it magic.
- notafraudster 4y ago
  From a cost-benefit perspective, it feels like most of the things we did to get sterile environments paid off with massive, dramatic drops in mortality and morbidity at every age group and the costs have been a bit of regulatory burden for business and maybe increases in childhood allergies which are likely to be nonfatal and low morbidity? That's a pretty good tradeoff. Even if you think obesity is a phenomenon entirely caused by gut biome and not food, it's still going to be a huge economic positive.
- parkingrift 4y ago
  > What needs to be done is not to eliminate those actors, but rather to make our bodies resilient to potentiel pathogens. If we expose ourselves to these pathogens and wait a few thousand years we might naturally evolve to be resilient. …otherwise I have no idea what you’re proposing here. You can’t just decide to be resilient. Pathogens kill people. They don’t die because they lacked willpower.
pifm_guy 4y ago
Purifying air seems like a tricky challenge. How much energy would it take to fractionally distill air? Ie. Liquify all the air in your house, boil off just the gasses you want, and pipe that back? Then you could choose for example to have 23% oxygen instead of 20% for a little more alertness, 0 ppm CO2 for a fresh feeling, and get rid of all the trace offgasses, even those that wouldn't be absorbed by activated charcoal.
- knodi123 4y ago
  We did that for my house for a while. It wasn't too expensive, just a couple million a month (after initial one-time costs like buying equipment and building the physical plant on a couple of neighboring acres). But in the end, factoring in plant maintenance and all the employees that it required, my family decided it would be more cost effective to just have weekly shipments of bottled gasses from a scientific supplier.
qubex 4y ago
Since UV can be pretty hazardous I’d like to add this video (courtesy of the inimitable Big Clive) for your consideration: https://youtu.be/2T39BHvrHZ0 https://youtu.be/2T39BHvrHZ0 (“How to use a UVC germicidal lamp safely”)
oifjsidjf 4y ago
> But the reasoning makes sense: down in that range, the penetration of such light is only a few microns, and it doesn't even get past the dead cells on the surface of the skin and the cornea of the eye! Ah yes, scientists saying "trust us, it won't harm the body" for the 1000th time, and then after a decade and two they will be proven wrong again. They never learn...

77 points by sohkamyung 4y ago

I'm a big fan of using UV for germicidal purposes, but I get extremely concerned when people propose using it in rooms where people are present, like the "just put it high up in a vaulted ceiling" approach discussed in the article. People can get eye damage from halogen lamps with cracked filters in school gymnasiums[1], and those ceilings are generally higher than you'd see in most other types of room. The potential to end up deploying something that ends up being another asbestos-type "oops, we gave an entire generation cataracts and skin cancer" situation really concerns me. I'd want to see either some very long term research indicating that it didn't happen with far-UV light at all, or that the lights were in fixtures that somehow completely prevented the people below from being exposed. [1] https://www.cdc.gov/mmwr/volumes/65/wr/mm6511a4.htm https://www.cdc.gov/mmwr/volumes/65/wr/mm6511a4.htm

Aperocky 4y ago

Bacterial heaven ensues.

joe_the_user 4y ago

I don't understand why there hasn't a lot of resources put into approaches like this.

themitigating 4y ago
Looks like researchers are looking into it "The technique works well, says William Bahnfleth, an architectural engineer at Pennsylvania State University in University Park who focuses on indoor air quality." Also the article notes there's a safety aspect
Animats 4y ago
It works, but it's hard to do. * The far-UV lamps cost way too much. * There are a sizable number of fake ones out there. * There aren't standards and inspection tools for this. A useful tool would be a UV detector on a stick. You touch it to the ceiling, and it reports on whether there's enough UV in the right wavelengths to kill viruses. The idea is to have emitters which radiate horizontally, with most of the UV up near the ceiling. You also need a handheld device which checks at eye level for excessive near UV. With both of those, you could quickly tell if a room had reliable virus protection.
- joe_the_user 4y ago
  All that makes sense - for an ordinary product in an ordinary market. But this seems like something that could make a serious dent in the covid situation and so government mandates and money could flow and get these much more widely deployed with strong standards.
  - epicureanideal 4y ago
    Also possibly useful military applications. Heck, have the soldiers wear some goggles that have UV protection and just saturate the room in virus killing UV periodically if there’s a suspected biological attack. Although, why not just put this UV emitter in a big box that has some kind of light filter on it to keep the UV inside rather than worrying about top of the room and so on?
    - Animats 4y ago
      Because you have to push the air through the box with fans. If you can make the ceiling area a kill zone for viruses, ordinary convection effects will push all the air through it regularly.
- NikkiA 4y ago
  Also, the UV light involved is very damaging to eyes (causing cataracts and macular degeneration), so it has to be kept entirely contained, yet have all/most of your breathable air pass through it somehow.
- vigeek 4y ago
  They make these for hvac systems, mines installed in the air return, fully enclosed it works well. When the heat or AC isn't in use, I just run the hvac system fan.
glenngillen 4y ago
I know of at least one company that is deploying them: https://gangigermicidalsystems.com.au/ https://gangigermicidalsystems.com.au/

a1371 4y ago

When you talk to Indoor Air Quality (IAQ) most are uncomfortable with UV. Reason being that while you can get rid of viruses, you can also create volatile compounds. Our homes' air is like a soup of natural and synthetic chemicals. From your flooring wear to your decor off-gassing to cooking, there are elements in your air that may be safe as they are, but they can completely change when they hit something volatile like ozone (from cars). Subsequently there can be a chain reaction with other compounds, potentially causing particles in your air that are bad for your health. If you could see that with magical glasses it would seem as if there are fireworks happening in your air triggered by those volatile compounds. So while UV has clear benefits, the byproducts that the lab conditions usually don't catch, make the applications limited.

bradknowles 4y ago
Most quality whole-home HEPA air filters I know of are available with UV lights that can be added to the mix to further help reduce the viral load in the house. And excessive ozone production is specifically avoided. For those units, I don't think there's anything to be concerned about here, except the added cost of the UV lighting and what might happen if you (or a technician) were accidentally exposed to the UV lighting during maintenance of the equipment. IMO, you're going to have to provide some extraordinary evidence if you want to claim UV health risks beyond these two factors.
wesapien 4y ago
My uncle has ozone generators in his home. One of them is industrial strength and he only runs it when he is leaving his house for awhile. Does ozone produce by products? I vaguely recall hospitals used ozone to clean n95 masks.
- colechristensen 4y ago
  Ozone itself is the main culprit.
- yummypaint 4y ago
  I think it's pretty well established that ozone can interact unpredictabily, especially with chemically complex modern building materials. Here is one anecdotal example: https://www.reddit.com/r/homeowners/comments/d2rjsb/ozone_generator_left_a_bad_odor/ https://www.reddit.com/r/homeowners/comments/d2rjsb/ozone_ge... N95 masks actually seem like one of the few use cases that make sense, as their composition is well known and they can be easily enclosed. Even when ozone generators work as expected, they can take months to remove odors from spaces.

amluto 4y ago

Obligatory Derek Lowe link: https://www.science.org/content/blog-post/two-twenty-two https://www.science.org/content/blog-post/two-twenty-two

Scoundreller 4y ago

Would like to see what my mini office heater can do. The air it outputs is about 75C and I like to think that would kill any viruses, but I guess it depends on whether the split second at that temperature would kill it or not.

abdullahkhalids 4y ago

If this is used inside homes and offices, how does one train their immune system, which requires constant low level exposure to foreign entities?

colechristensen 4y ago
The problem is enclosed spaces build up pretty high levels of exposure you just don’t find in natural environments. There also tend to have much less of the harmless diversity that outside has.
- beebeepka 4y ago
  Open doors and windows to create a current. Do it on a daily basis
  - Auracle 4y ago
    That’s not an option for most climates.
    - beebeepka 4y ago
      Care to elaborate? I would think it depends more on the type of building than anything else. Having wind helps tremendously, of course
      - colechristensen 4y ago
        It’s 25 F outside right now :) not such a fan of ventilating now…
        beebeepka 4y ago
        -4c is nothing. In fact, it'll make the procedure easier. I do at -20c and below
      - 4y ago

kumarvvr 4y ago

Would they also degrade paintings, papers, photos, display devices etc?

unglaublich 4y ago
That's why the UV treatment is done in an enclosure through which air is vented.

nicodds 4y ago

I think mechanical ventilation (MV) is less risky and almost as effective in preventing spread of viruses. Probably, coupling MV with a boxed UV lamp (no UV radiation outside the box) would be more effective.

sberder 4y ago

I haven't seen one of the main arguments against UV efficiency in the context of an HVAC system. Most common UV solutions simply cannot clean at the speed the air goes through the systems in most buildings. When you have to maintain 6 air changes per hour, the UV solutions are simply not manageable. There are other limitations but that's the main issue as far as I can tell talking to facility managers.

vigeek 4y ago
This is what I have installed at my house, it works well.
dtgriscom 4y ago
A room, its occupants and its HVAC is a steady state system, with people emitting virus particles and the HVAC system removing it. The goal is to have the HVAC system remove virus particles quickly enough so that the average particle density is low. You don't need the air coming out of the vent to be completely aseptic; you just need to remove a significant amount of the virus on each pass.

ciconia 4y ago

I find the obsession with having a sterile environment ridiculous. Our bodies themselves are teeming with microbes and viruses, actually our bodies contain more of them than our own human cells. They play an important role in our digestive system, as well as our metabolism and also keeping our immune system on its guard. What needs to be done is not to eliminate those actors, but rather to make our bodies resilient to potentiel pathogens.

Gigachad 4y ago
For viruses sure, but other things like air filters make sense. Nothing good comes from breathing combustion engine exhaust or gas stove combustion byproducts. If you live anywhere near a coal mine or power plant you are also getting a good dose of radioactive dust although I’m not sure a hepa filter is good enough there.
goodpoint 4y ago
> make our bodies resilient to potentiel pathogens How? Magic?
- refurb 4y ago
  Immune system? Some might call it magic.
notafraudster 4y ago
From a cost-benefit perspective, it feels like most of the things we did to get sterile environments paid off with massive, dramatic drops in mortality and morbidity at every age group and the costs have been a bit of regulatory burden for business and maybe increases in childhood allergies which are likely to be nonfatal and low morbidity? That's a pretty good tradeoff. Even if you think obesity is a phenomenon entirely caused by gut biome and not food, it's still going to be a huge economic positive.
parkingrift 4y ago
> What needs to be done is not to eliminate those actors, but rather to make our bodies resilient to potentiel pathogens. If we expose ourselves to these pathogens and wait a few thousand years we might naturally evolve to be resilient. …otherwise I have no idea what you’re proposing here. You can’t just decide to be resilient. Pathogens kill people. They don’t die because they lacked willpower.

pifm_guy 4y ago

Purifying air seems like a tricky challenge. How much energy would it take to fractionally distill air? Ie. Liquify all the air in your house, boil off just the gasses you want, and pipe that back? Then you could choose for example to have 23% oxygen instead of 20% for a little more alertness, 0 ppm CO2 for a fresh feeling, and get rid of all the trace offgasses, even those that wouldn't be absorbed by activated charcoal.

knodi123 4y ago
We did that for my house for a while. It wasn't too expensive, just a couple million a month (after initial one-time costs like buying equipment and building the physical plant on a couple of neighboring acres). But in the end, factoring in plant maintenance and all the employees that it required, my family decided it would be more cost effective to just have weekly shipments of bottled gasses from a scientific supplier.

qubex 4y ago

Since UV can be pretty hazardous I’d like to add this video (courtesy of the inimitable Big Clive) for your consideration: https://youtu.be/2T39BHvrHZ0 https://youtu.be/2T39BHvrHZ0 (“How to use a UVC germicidal lamp safely”)

oifjsidjf 4y ago

> But the reasoning makes sense: down in that range, the penetration of such light is only a few microns, and it doesn't even get past the dead cells on the surface of the skin and the cornea of the eye! Ah yes, scientists saying "trust us, it won't harm the body" for the 1000th time, and then after a decade and two they will be proven wrong again. They never learn...