Is there any known mechanism through which air quality affects cognitive performance? The article does not suggest or refer to any research on the subject.
The referenced article there explicitly does not give a mechanism:
Changes in the brain chemistry or composition are likely more plausible channels between air pollution and cognition. It is beyond the scope of this paper to test the exact mechanism, so we leave it as agenda for future research.
> It's not clear precisely how pollution impacts cognitive decline, though Chen suggests that pollution may have a negative effect on the brain's white matter, which could vary between men and women. As NPR has reported, "the brain's white matter coordinates communication among brain regions."
> James Hendrix, the director of Global Science Initiatives at the Alzheimer's Association, was skeptical of the claim that pollution impacts white matter. "I think that's speculation. I think we don't have a direct cause and effect that can be proven," he said.
Your first link says the mechanism is unknown right in the beginning. Third link doesn't mention mechanisms at all. Only the second link attempts some guesses. But it still concludes that "It is beyond the scope of this paper to test the exact mechanism, so we leave it as agenda for future research."
Typically, knowing the mechanism comes long after solid evidence of the effect.
The mechanisms by which cigarettes cause lung cancer are surprisingly complex and weren't fully understood for a long time, but it's obvious that some kind of mechanism is plausible.
So usually the bar for taking something seriously is: statistical evidence of a significant harmful effect, and at least one plausible hypothesis for a mechanism. But you don't have to be sure of the mechanism.
The apa article seems to have the best info. This is from a study of genetically identical mice:
To find out more about the underlying cause of those behavioral changes, Nelson compared the brains of mice that had been exposed to dirty air with brains of mice that hadn't. He found a number of striking differences. For starters, mice exposed to particulate matter had increased levels of cytokines in the brain. (Cytokines are cell-signaling molecules that regulate the body's inflammatory response.) That wasn't entirely surprising, since previous studies investigating the cardiovascular effects of air pollution on mice had found widespread bodily inflammation in mice exposed to the pollution.
More surprisingly, Nelson also discovered physical changes to the nerve cells in the mouse hippocampus, a region known to play a role in spatial memory. Exposed mice had fewer spines on the tips of the neurons in this brain region. "Those [spines] form the connections to other cells," Nelson says. "So you have less dendritic complexity, and that's usually correlated with a poorer memory."
The changes are alarming and surprising, he says. "I never thought we'd actually see changes in brain structure."
Increased CO2 levels in the air will reduce mental performance. I mean it isn't a ton unless you are seriously sealed up, and I don't know about particulates and other pollution. But a poorly ventilated room can have CO2 level rise double that of a well ventilated room and has been measured both in actual rooms and building CO2 levels and with subjects being tested for mental performance under experimental conditions with controlled CO2 levels.
This book has some good info:
Norwegian Secrets for Bringing Natural Air and Light into Your Home and Office to Dramatically Improve Health and Happiness
Andrew Gelman: "No, I don’t think that this study offers good evidence that installing air filters in classrooms has surprisingly large educational benefits."
This is so good! Gelman's comments on the study are a better HN post than this article.
This is important stuff - you can already see people researching air filters in other comments, taking the supposed results of this study as settled truth.
I'd just like to say, before the mods change the thread link, that the original article is important to understand the context of why air filters were installed.
Even if the Vox article is potentially flawed you need to read both to grasp the full picture.
Normally we'd merge these submissions but the topics are sufficiently different that I think that might add confusion. I've moved most of the comments from this subthread to that one, though.
All: if you want to comment on the Gelman article, please do so in the other thread, where your comment will feel more at home and get more attention.
Half of the reason I enjoy working from home, is that my office has horrible stagnant air. I think far better anywhere (home, coffee shops, the park) that isn't my office.
I've actually purchased a couple of indoor plants, a snake plant and a peace lily, to help generate oxygen indoors. I noticed the air "tasted" better about a week after I put them in the room. And I also noticed the air in my office feels better than the air in my apartment which has no plants. Whether that's something measurable I don't know, but while having these plants here I feel like I perform better.
> Photosynthesis converts CO2 to O2, but plants also respire. During respiration they convert sugar and oxygen into CO2 and water. This is the reverse of photosynthesis, and it happens in all cells, all of the time, day and night.
Interesting, I wonder how that'll contribute to the snowball effect of global warming since as it gets hotter I'm sure they'll perspire more.
Plants solve prespiration by bringing water from their roots, up to their leaves. They burn sugars for energy they need to live, not for water they need to stay cool. Sugars are difficult to make, water can just be pulled directly from their environment.
Plants work on a similar principle as human nutrition. CO2 in - CO2 out = weight gain. A growing plant is on average* a net absorber of carbon dioxide.
* On average, not constantly. Since they can't do photosynthesis in the dark, they release CO2 at night.
The sources in that link seem to suggest that the benefits come from removal of CO2 and volatile organic compounds from the environment, versus attributing the benefits to oxygen generation.
As an advocate for more indoor plants, I’m glad they’re making your environments feel better! The “taste” you’re describing is probably just the normal byproducts of the bacteria in the plant soil. Most folks plants collections don’t actually produce the amount of oxygen and filtration that the Internet would have you believe. Unless you’ve created a near greenhouse. Which I’d be a fan of. But I feel that they do make out living spaces feel cozier and smell better :)
If you want your plants to provide even 10% of that number - 40L, your houseplants will need to take CO2 out of the air, store the carbon, and release the oxygen.
This means that they will need to grow by ~300g - nearly a pound, a day, in order to produce 40L of oxygen.
Unless your home is a wild, gymnasium-sized jungle, your houseplants aren't producing any measurable amounts of oxygen. And, as a bonus point, they aren't even cleaning your air. (Although they do provide a lot of new surfaces for dust to settle, that you have to clean.)
If you want to breathe better, open your windows. If your outside air has too much crap in it, buy a HEPA filter. If you breathe fine, and there's too much crap in the air, buy a fan with a HEPA filter attached to it (Also known as an air purifier.)
And what should you do if your outside air has in it too much CO/methane/other small-molecule gas particles that HEPA filters have no hope of trapping?
Ignoring plants, there's gotta be some solution to this. What do they do to recycle the air up at the International Space Station?
> And what should you do if your outside air has in it too much CO/methane/other small-molecule gas particles that HEPA filters have no hope of trapping?
You pack up, and move somewhere that's not the equivalent of sitting in the middle of a crude oil refinery.
Plants won't deal with these problems, either.
> What do they do to recycle the air up at the International Space Station?
For the most part, they chemically scrub the CO2 out[1], use the equivalents of catalytic converters to pull things like trace ammonia out of the air, and move on with life. There isn't a lot of heavy industry that happens inside the ISS.
If the air outside your window is literal poison, your house isn't sufficiently hermetically sealed for this to work.
[1] The actual process they use is the Sabatier process:
2H20 + E => 2H2 + O2
CO2 + 2H2 => CH4 + O2.
The water is brought up in resupply missions, the methane is vented into space. It's not a closed cycle (Which would require an enormous amount of plants), and its never going to have one, because it's going to be decommissioned in the next ~15 years.
> You pack up, and move somewhere that's not the equivalent of sitting in the middle of a crude oil refinery.
I would posit that for many people (e.g. citizens of China or India), "moving somewhere" where you're not constantly exposed to small-molecule pollutants would require more effort (e.g. acquiring a different citizenship) than would be required to atmospherically decouple your house.
There's not much of a middle ground between 'perfectly affordable consumer grade air filters that get most of the crap out of the air', and 'hermetically isolated, self-sustaining atmosphere'. HEPA filters work quite well at what they are designed to do, and it is generally cheaper to move someplace else, then to go over-board with improving your filtration.
The next step past HEPA (for consumers) is activated carbon/charcoal [0]. Most higher-end air purifiers have this included, which helps with filtering gases. I personally have an Airmega [1] and have been very happy with it. It was particularly helpful when there was smoke from fires in NorCal -- I had far better air quality at home than at the office.
Assuming the filters do what the article supposes they do, what would be the cheapest and easiest way to test the air quality in my home and workplace?
It would be interesting if we could monitor productivity in the major Australian CBDs these days. A lot of the big office buildings don't have the capability to filter the unhealthy / toxic bushfire smoke, and the workers get to suffer.
And on that, good luck trying to find any purifiers, anywhere in Australian stores.
At home it matters too. I recover faster from chest colds when I remember to keep the HEPA filter running. (instead of a simple speed knob, it boots up to a multilingual color display that I can't even dim, and of course the filter defaults to "off")
Here is a common air quality problem. Anybody have ideas?
My house is in a hot and humid area, so I run the air conditioning most of the year. The duct work appears to be made of bare fiberglass pressed into sheets, with foil on the outside. This is cheap, quiet, and thermally insulating. It does however have a soft highly porous surface that collects black mold.
It doesn't appear possible to do anything about the mold. Thanks to the soft porous surface, scrubbing would tear up the ducts and be ineffective.
Ideally the ducts would have a polished bare silver surface, sturdy enough to scrub. Well, nobody has that, it would be expensive, and I'd have to rip out the drywall of nearly every room in order to install something like that.
Remove the material with mold from the space. Duct work is a terrible idea in humid climates. It's better to get those individual wall AC units per room. Mold is nasty stuff that will cause long term health problems.
FWIW, I removed the galvanized steel ducts from my house. The insides were disgusting, despite the professional vacuum service. My allergy symptoms and whatnot improved quite a bit afterwards.
Good luck. Please post whatever experiments you try.
You have duct board. It can’t be cleaned, only replaced. If you want to spend a lot look at double wall sheet metal ducts and never let your house sit without dehumidification.
When we ran a daycare we were specifically told NOT to install air filters because there was research that suggested it would cause the children to develop problems and have a reduced resistance. I would guess for older kids it's fine, but you might want to consider that if you have or will have kids when talking about the home, or come up with some mitigation strategies.
50 comments
[ 2.7 ms ] story [ 103 ms ] threadChanges in the brain chemistry or composition are likely more plausible channels between air pollution and cognition. It is beyond the scope of this paper to test the exact mechanism, so we leave it as agenda for future research.
> It's not clear precisely how pollution impacts cognitive decline, though Chen suggests that pollution may have a negative effect on the brain's white matter, which could vary between men and women. As NPR has reported, "the brain's white matter coordinates communication among brain regions."
> James Hendrix, the director of Global Science Initiatives at the Alzheimer's Association, was skeptical of the claim that pollution impacts white matter. "I think that's speculation. I think we don't have a direct cause and effect that can be proven," he said.
https://www.pnas.org/content/115/37/9193
https://www.apa.org/monitor/2012/07-08/smog
The mechanisms by which cigarettes cause lung cancer are surprisingly complex and weren't fully understood for a long time, but it's obvious that some kind of mechanism is plausible.
So usually the bar for taking something seriously is: statistical evidence of a significant harmful effect, and at least one plausible hypothesis for a mechanism. But you don't have to be sure of the mechanism.
To find out more about the underlying cause of those behavioral changes, Nelson compared the brains of mice that had been exposed to dirty air with brains of mice that hadn't. He found a number of striking differences. For starters, mice exposed to particulate matter had increased levels of cytokines in the brain. (Cytokines are cell-signaling molecules that regulate the body's inflammatory response.) That wasn't entirely surprising, since previous studies investigating the cardiovascular effects of air pollution on mice had found widespread bodily inflammation in mice exposed to the pollution.
More surprisingly, Nelson also discovered physical changes to the nerve cells in the mouse hippocampus, a region known to play a role in spatial memory. Exposed mice had fewer spines on the tips of the neurons in this brain region. "Those [spines] form the connections to other cells," Nelson says. "So you have less dendritic complexity, and that's usually correlated with a poorer memory."
The changes are alarming and surprising, he says. "I never thought we'd actually see changes in brain structure."
https://www.harpercollins.com/9780062896223/skogluft/
https://statmodeling.stat.columbia.edu/2020/01/09/no-i-dont-...
This is important stuff - you can already see people researching air filters in other comments, taking the supposed results of this study as settled truth.
Even if the Vox article is potentially flawed you need to read both to grasp the full picture.
Normally we'd merge these submissions but the topics are sufficiently different that I think that might add confusion. I've moved most of the comments from this subthread to that one, though.
All: if you want to comment on the Gelman article, please do so in the other thread, where your comment will feel more at home and get more attention.
The TL;DR is that you're not likely to have enough plants to make a significant difference in terms of CO2/oxygen.
Doesn't mean there's no positive effect, but it's probably not due to oxygen levels.
Interesting, I wonder how that'll contribute to the snowball effect of global warming since as it gets hotter I'm sure they'll perspire more.
So, it won't be a noticeable effect.
* On average, not constantly. Since they can't do photosynthesis in the dark, they release CO2 at night.
https://www.theatlantic.com/science/archive/2019/03/indoor-p...
If you want your plants to provide even 10% of that number - 40L, your houseplants will need to take CO2 out of the air, store the carbon, and release the oxygen.
This means that they will need to grow by ~300g - nearly a pound, a day, in order to produce 40L of oxygen.
Unless your home is a wild, gymnasium-sized jungle, your houseplants aren't producing any measurable amounts of oxygen. And, as a bonus point, they aren't even cleaning your air. (Although they do provide a lot of new surfaces for dust to settle, that you have to clean.)
If you want to breathe better, open your windows. If your outside air has too much crap in it, buy a HEPA filter. If you breathe fine, and there's too much crap in the air, buy a fan with a HEPA filter attached to it (Also known as an air purifier.)
If you want plants near you, buy plants.
Ignoring plants, there's gotta be some solution to this. What do they do to recycle the air up at the International Space Station?
You pack up, and move somewhere that's not the equivalent of sitting in the middle of a crude oil refinery.
Plants won't deal with these problems, either.
> What do they do to recycle the air up at the International Space Station?
For the most part, they chemically scrub the CO2 out[1], use the equivalents of catalytic converters to pull things like trace ammonia out of the air, and move on with life. There isn't a lot of heavy industry that happens inside the ISS.
If the air outside your window is literal poison, your house isn't sufficiently hermetically sealed for this to work.
[1] The actual process they use is the Sabatier process:
2H20 + E => 2H2 + O2
CO2 + 2H2 => CH4 + O2.
The water is brought up in resupply missions, the methane is vented into space. It's not a closed cycle (Which would require an enormous amount of plants), and its never going to have one, because it's going to be decommissioned in the next ~15 years.
I would posit that for many people (e.g. citizens of China or India), "moving somewhere" where you're not constantly exposed to small-molecule pollutants would require more effort (e.g. acquiring a different citizenship) than would be required to atmospherically decouple your house.
For that kind of money, you may as well just buy an investor visa.
[0] https://en.wikipedia.org/wiki/Carbon_filtering
[1] https://www.cowaymega.com/product/coway-airmega-400s-white/
Edit: Example @ https://aqicn.org/sensor/sds011/
I realised I pasted the wrong link above, although still of interest. Anyway, here's a Pie specific article: https://www.raspberrypi.org/blog/monitor-air-quality-with-a-...
It would be interesting if we could monitor productivity in the major Australian CBDs these days. A lot of the big office buildings don't have the capability to filter the unhealthy / toxic bushfire smoke, and the workers get to suffer.
And on that, good luck trying to find any purifiers, anywhere in Australian stores.
I'm in Canada and have had days of smoke from the Fort Mac fires roll through -- it's rough.
Here is a common air quality problem. Anybody have ideas?
My house is in a hot and humid area, so I run the air conditioning most of the year. The duct work appears to be made of bare fiberglass pressed into sheets, with foil on the outside. This is cheap, quiet, and thermally insulating. It does however have a soft highly porous surface that collects black mold.
It doesn't appear possible to do anything about the mold. Thanks to the soft porous surface, scrubbing would tear up the ducts and be ineffective.
Ideally the ducts would have a polished bare silver surface, sturdy enough to scrub. Well, nobody has that, it would be expensive, and I'd have to rip out the drywall of nearly every room in order to install something like that.
What do I do?
Ductless mini split units.
Regardless of what you have periodic maintenance is what makes a difference.
FWIW, I removed the galvanized steel ducts from my house. The insides were disgusting, despite the professional vacuum service. My allergy symptoms and whatnot improved quite a bit afterwards.
Good luck. Please post whatever experiments you try.