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You seem to have relatively clean air already. I probably wouldn't even bother with air purifiers in such a situation. Where did you buy air filters? I live in

You seem to have relatively clean air already. I probably wouldn't even bother with air purifiers in such a situation. Where did you buy air filters? I live in a third-world country and couldn't find them anywhere, so I had to buy a factory-built purifier. It really struggles to keep up when it's 1000+ µg/m³ outside. I'd like to add a second one (preferably DIY).

DeRock 5y ago
Sure, air quality is relative, but 100 AQI is the point where I start getting headaches. Obviously it can get much worse. I got the air filters on Amazon, which can be US centric, but usually you would get them at a home/hardware store. They are made for slotting into a furnace/HVAC set up. For places where that is less common, they may be harder to find.
dynm 5y ago
> You seem to have relatively clean air already. I probably wouldn't even bother with air purifiers in such a situation. By my estimates, a lifelong exposure to 33 µg/m³ rather than 0 µg/m³ would on average result in a loss of around 1 disability adjusted life year. https://dynomight.net/air/#a-heuristic-to-quantify-harms https://dynomight.net/air/#a-heuristic-to-quantify-harms Obviously this is very hard to estimate and you shouldn't trust this as anything more than at most a rough order of magnitude estimate. But it does suggest that the ambient levels they are experiencing are worth reducing if you can do it easily.
- fighterpilot 5y ago
  Might those numbers might be exaggerated a bit due to confounders? Specifically, the high density and traffic causing stress.
  - dynm 5y ago
    It's entirely possible! But my perspective is that there's a very one-sided risk. It's extremely unlikely that particles are beneficial. Thus, given the uncertainty I think it's good decision theory to run a purifier, especially given how easy it is relative to other lifestyle changes that could plausibly have a benefit of the same magnitude.
    - emn13 5y ago
      Running a purifier does cause noise however, which isn't healthy; assuming your purifier is close by. (No idea at what point those two effects are of similar impact.)
DeRock 5y ago
> It really struggles to keep up when it's 1000+ µg/m³ outside Also worth noting that 1000ug/m³ is not accurate, maybe you are thinking of some other measurement? In the literal middle of a forest fire, you may see readings of ~300 ug/m³. No where on earth sees readings of 1000+ µg/m³.
- 5e92cb50239222b 5y ago
  It is very much accurate. This is a pretty typical PM2.5 level at winter time where I live. Put a few thousand houses heated with coal close together, add −30-40 °C winters, a particularly bad location where wind almost never blows (maybe ~30 days per year total), and voila.
  - Charybdis 5y ago
    I think you have us all curious now - where do you live? Sounds like Siberia, except I'd expect there to be more wind.
    - 5e92cb50239222b 5y ago
      Relatively close, but no cigar. I'll quickly deanon myself if I describe the exact place, there's not many HNers here.
  - DeRock 5y ago
    In California, there is the Caldor Fire raging right now in South Lake Tahoe. Heres what it looks like on the ground: https://www.reddit.com/r/weather/comments/pfczpl/caldor_fire_creates_its_own_weather_in_lake_tahoe/ https://www.reddit.com/r/weather/comments/pfczpl/caldor_fire... The highest purple air sensor, near/on the fire front, in raw PM2.5 ug/m³ is at 368 when I checked: https://www.purpleair.com/map?opt=1/mPM25/a10/cC0&select=73559#11.5/38.8917/-119.9743 https://www.purpleair.com/map?opt=1/mPM25/a10/cC0&select=735...
    - coryrc 5y ago
      I expect there are a lot of particles bigger than 2.5 um?
amluto 5y ago
Do you live in a place where forced-air heating is common? If so, you should be able to buy filters wherever people go to buy miscellaneous hardware for houses. In the US, they are rated on a scale called MERV. In other countries, other rating systems are used. You want something at or near the high end of the scale — getting near 100% removal with, for example, a real HEPA filter is unnecessary and potentially counterproductive, but getting to at least, say, 30% reduction in fine particles per pass is important. In the US, this is around MERV 13.
bluGill 5y ago
> You seem to have relatively clean air already. I probably wouldn't even bother with air purifiers in such a situation. Everyone should have filters. Filters are for more than dust, they have also been shown to greatly reduce the amount of COVID in the room air. (i would assume flu and other viruses as well). Cheap and easy, with no stupid controversy like masks or a vaccine (even though both are better than an air filter, every little bit helps)
- OJFord 5y ago
  'Masks', as worn by most, are assuredly not. Edit: I'm not anti-mask. I would love it if you explained how ill-fitting cloth in a single pass is better than multi-pass HEPA or equivalent filtration rather than (or even as well as) down-voting, though.
  - deleted 5y ago
    [deleted]
  - JohnBooty 5y ago
    Sure, yeah. A simple cloth mask doesn't really protect the wearer; it protects others from the wearer. It slows droplets down as you exhale them. So they travel X feet, instead of X+Y feet. Depending on air currents and other variables the level of protection this offers others will range from "nothing at all" to "some". Obviously, a HEPA filter is orders of magnitude better. But, is there a HEPA filter directly between you and the person next to you in line at the supermarket?
    - OJFord 5y ago
      > A simple cloth mask doesn't really protect the wearer; it protects others from the wearer. Sure. I'd call that 'different' rather than 'better', but I suppose it's subjective. > Obviously, a HEPA filter is orders of magnitude better. You would think, and yet my comment saying so, objecting to 'masks are better than an air filter' (when qualified to ill-fitting cloth as worn by most) is apparently highly objectionable. > But, is there a HEPA filter directly between you and the person next to you in line at the supermarket? Not a comparison I made, but yeah, if I went to a supermarket (I'm not, because I almost entirely had groceries delivered pre-pandemic, so now easily enough entirely) I would wear an FFP3 dust mask rather than ill-fitting cloth, which is two nines to HEPA's 3.5. (More than that is probably not justified since fit won't be perfect, some leakage. Industrially etc. where there's a need for greater filtration I expect that's when you have to step up to fully enclosed hoods. I digress..)
SilverRed 5y ago
I haven't been able to prove this well yet but I got the dyson air purifier and it seems to have done really well at reducing my hey fever. Even when leaving home it seems to be not much of an issue. Possibly just reducing the allergens in the air for most of the time makes it not an issue when I experience them outside for short periods.
- manmal 5y ago
  Hay fever that’s caused by particulates in your house sounds weird. Maybe get a check for mold?
  - SilverRed 5y ago
    The pollen comes in through the windows and gets me hard. While I'm at home I have no issues, when I go outside I start to get hit with them but by the time it's really kicking in I'm usually on my way home again anyway. It's hard to actually prove the air filter did anything since a lot of factors for me have changed since last season but this year I am affected far less than I was last and not feeling any effects right now while some coworkers are.
Bertio 5y ago
During fire season this year, living in one of the cities with the worst air quality in Canada this year, I had to double up my fans to keep up when it reaches 400+ US pm2.5 aqi in my home office that is about 300 sq ft. I am using filtrete 1900 20x20x1 from amazon (Canada) I also have a Dyson air cleaner and it works for moderate to light smoke but it's just not enough for heavy smoke.

DeRock 5y ago

Sure, air quality is relative, but 100 AQI is the point where I start getting headaches. Obviously it can get much worse. I got the air filters on Amazon, which can be US centric, but usually you would get them at a home/hardware store. They are made for slotting into a furnace/HVAC set up. For places where that is less common, they may be harder to find.

dynm 5y ago

> You seem to have relatively clean air already. I probably wouldn't even bother with air purifiers in such a situation. By my estimates, a lifelong exposure to 33 µg/m³ rather than 0 µg/m³ would on average result in a loss of around 1 disability adjusted life year. https://dynomight.net/air/#a-heuristic-to-quantify-harms https://dynomight.net/air/#a-heuristic-to-quantify-harms Obviously this is very hard to estimate and you shouldn't trust this as anything more than at most a rough order of magnitude estimate. But it does suggest that the ambient levels they are experiencing are worth reducing if you can do it easily.

fighterpilot 5y ago
Might those numbers might be exaggerated a bit due to confounders? Specifically, the high density and traffic causing stress.
- dynm 5y ago
  It's entirely possible! But my perspective is that there's a very one-sided risk. It's extremely unlikely that particles are beneficial. Thus, given the uncertainty I think it's good decision theory to run a purifier, especially given how easy it is relative to other lifestyle changes that could plausibly have a benefit of the same magnitude.
  - emn13 5y ago
    Running a purifier does cause noise however, which isn't healthy; assuming your purifier is close by. (No idea at what point those two effects are of similar impact.)

DeRock 5y ago

> It really struggles to keep up when it's 1000+ µg/m³ outside Also worth noting that 1000ug/m³ is not accurate, maybe you are thinking of some other measurement? In the literal middle of a forest fire, you may see readings of ~300 ug/m³. No where on earth sees readings of 1000+ µg/m³.

5e92cb50239222b 5y ago
It is very much accurate. This is a pretty typical PM2.5 level at winter time where I live. Put a few thousand houses heated with coal close together, add −30-40 °C winters, a particularly bad location where wind almost never blows (maybe ~30 days per year total), and voila.
- Charybdis 5y ago
  I think you have us all curious now - where do you live? Sounds like Siberia, except I'd expect there to be more wind.
  - 5e92cb50239222b 5y ago
    Relatively close, but no cigar. I'll quickly deanon myself if I describe the exact place, there's not many HNers here.
- DeRock 5y ago
  In California, there is the Caldor Fire raging right now in South Lake Tahoe. Heres what it looks like on the ground: https://www.reddit.com/r/weather/comments/pfczpl/caldor_fire_creates_its_own_weather_in_lake_tahoe/ https://www.reddit.com/r/weather/comments/pfczpl/caldor_fire... The highest purple air sensor, near/on the fire front, in raw PM2.5 ug/m³ is at 368 when I checked: https://www.purpleair.com/map?opt=1/mPM25/a10/cC0&select=73559#11.5/38.8917/-119.9743 https://www.purpleair.com/map?opt=1/mPM25/a10/cC0&select=735...
  - coryrc 5y ago
    I expect there are a lot of particles bigger than 2.5 um?

amluto 5y ago

Do you live in a place where forced-air heating is common? If so, you should be able to buy filters wherever people go to buy miscellaneous hardware for houses. In the US, they are rated on a scale called MERV. In other countries, other rating systems are used. You want something at or near the high end of the scale — getting near 100% removal with, for example, a real HEPA filter is unnecessary and potentially counterproductive, but getting to at least, say, 30% reduction in fine particles per pass is important. In the US, this is around MERV 13.

bluGill 5y ago

> You seem to have relatively clean air already. I probably wouldn't even bother with air purifiers in such a situation. Everyone should have filters. Filters are for more than dust, they have also been shown to greatly reduce the amount of COVID in the room air. (i would assume flu and other viruses as well). Cheap and easy, with no stupid controversy like masks or a vaccine (even though both are better than an air filter, every little bit helps)

OJFord 5y ago
'Masks', as worn by most, are assuredly not. Edit: I'm not anti-mask. I would love it if you explained how ill-fitting cloth in a single pass is better than multi-pass HEPA or equivalent filtration rather than (or even as well as) down-voting, though.
- deleted 5y ago
  [deleted]
- JohnBooty 5y ago
  Sure, yeah. A simple cloth mask doesn't really protect the wearer; it protects others from the wearer. It slows droplets down as you exhale them. So they travel X feet, instead of X+Y feet. Depending on air currents and other variables the level of protection this offers others will range from "nothing at all" to "some". Obviously, a HEPA filter is orders of magnitude better. But, is there a HEPA filter directly between you and the person next to you in line at the supermarket?
  - OJFord 5y ago
    > A simple cloth mask doesn't really protect the wearer; it protects others from the wearer. Sure. I'd call that 'different' rather than 'better', but I suppose it's subjective. > Obviously, a HEPA filter is orders of magnitude better. You would think, and yet my comment saying so, objecting to 'masks are better than an air filter' (when qualified to ill-fitting cloth as worn by most) is apparently highly objectionable. > But, is there a HEPA filter directly between you and the person next to you in line at the supermarket? Not a comparison I made, but yeah, if I went to a supermarket (I'm not, because I almost entirely had groceries delivered pre-pandemic, so now easily enough entirely) I would wear an FFP3 dust mask rather than ill-fitting cloth, which is two nines to HEPA's 3.5. (More than that is probably not justified since fit won't be perfect, some leakage. Industrially etc. where there's a need for greater filtration I expect that's when you have to step up to fully enclosed hoods. I digress..)

SilverRed 5y ago

I haven't been able to prove this well yet but I got the dyson air purifier and it seems to have done really well at reducing my hey fever. Even when leaving home it seems to be not much of an issue. Possibly just reducing the allergens in the air for most of the time makes it not an issue when I experience them outside for short periods.

manmal 5y ago
Hay fever that’s caused by particulates in your house sounds weird. Maybe get a check for mold?
- SilverRed 5y ago
  The pollen comes in through the windows and gets me hard. While I'm at home I have no issues, when I go outside I start to get hit with them but by the time it's really kicking in I'm usually on my way home again anyway. It's hard to actually prove the air filter did anything since a lot of factors for me have changed since last season but this year I am affected far less than I was last and not feeling any effects right now while some coworkers are.

Bertio 5y ago

During fire season this year, living in one of the cities with the worst air quality in Canada this year, I had to double up my fans to keep up when it reaches 400+ US pm2.5 aqi in my home office that is about 300 sq ft. I am using filtrete 1900 20x20x1 from amazon (Canada) I also have a Dyson air cleaner and it works for moderate to light smoke but it's just not enough for heavy smoke.