I'm all for installing air filters in classrooms for a number of reasons, but I also think the extreme results from this study aren't going to hold up to further research.
From the paper:
> To do so, I leverage a unique setting arising from the largest gas leak in United States history, whereby the offending gas company installed air filters in every classroom, office and common area for all schools within five miles of the leak (but not beyond). This variation allows me to compare student achievement in schools receiving air filters relative to those that did not using a spatial regression discontinuity design.
In other words, the paper looked at test scores at different schools in different areas on different years and assumed that the only change was the air filters. Anyone who has worked with school kids knows that the variations between classes from year to year can be extreme, as can differences produced by different teachers or even school policies.
Again, I think air filtration is great indoors, but expecting test scores to improve dramatically like this is not realistic. This feels like another extremely exaggerated health claim, like past claims made about fish oil supplements. Fish oil was briefly thought to have extreme positive health benefits from a number of very small studies like this, but as sample sizes became larger and studies became higher quality, most of the beneficial effects disappeared.
I would also think there is a bias of schools spending extra money and effort towards student improvements if they are willing to go so far as allocate funding for air filtration systems. A better method would be to just give some schools air filtration for free and see if things help without any other major changes.
To me its like looking at schools that buy newer buses and trying to show new buses improve test scores. When in practice the only schools that are buying any significant number of new buses have far more money coming in than in the past and have a lot more to spend on students compared to other schools, which is way more relevant than what year a kid's bus is made. Maybe better buses would improve scores too, but there is no way to tell if 95% of an improvement is due to other unrelated factors based on funding.
I would also expect the estimated magnitude of the effect to go down over time, but that's just my general attitude to these kinds of things, the fact is that the discontinuity design that they use already accounts for variations between classes, teachers, schools, years. The way it works is that some unexpected event that applies to some people but not others is taken to represent a natural experiment, and then variation between groups before the event is compared to variation between groups after the event. The comparison is never against no variation.
The smoking gun is really in Table 3 and Table 4, where you can see that the effects that were observed are compatible with a population effect of 0, or alternatively you can look at Figure 2 and note that you could draw a straight line (no effect) within the confidence bands. Doesn't mean the effect is not there, but that there's insufficient evidence that it is, and that we should indeed be very careful about taking the estimates at face value.
Based on your comment, the effect could be larger as well as smaller.
All research is met on HN by people who know better and will tell you why it's flawed. There isn't a greater collection of expertise in the history of the world than on HN.
Edit: I meant to add: What value can we find in this research? It wasn't published as scripture, the perfect answer to all our problems. It's one study of some interesting events and data; what can we get out of it?
I wish we made more efforts to check air quality. I went to a great school, and the water filter hadnt been replaced since 2005 (it was 2012 at the time, and filters were supposed to be replaced every 6 months). My point is people take it for granted that air quality or water quality in the US is great, but if we checked, I bet most of us are exposed to cancerous materials all the time that could be easily prevented (the water stations rn are made of plastic (PVC), which leaches in the water over time and leads to nanoplastics accumulating in all of us. Easily prevented through more expensive steel pipes). Hell, my office had asbestos in the ceiling that was painted over! It sucks we lack regulation, as I do not believe it is my job to check these things and report them, and I got tired of it. Given the EPA is lacking funds, it is imperative all of us do due diligence so our children do not experience the cancer rates that are ravaging us (our cancer rates are 30% higher than Europe once you rule out lung cancer, which is a result of their smoking habits. The europeans love their cigs).
Maybe the tests results are better because the children are more rested on the day of the test. Maybe the hum of the machine creates some kind of meditative noise that helps children concentrate. Or maybe none of that is true..
I'm a big fan of air filters and have many in my own home that have made a big difference in quality of life as I live in a high pollen area. They can help with a lot more irritants as well that some students may be sensitive to (i.e., some students may study better if their immune system isn't in overdrive for half the school year like mine was). I'm not sure how these would help with natural gas though. I can't read the article due to paywall. Some VOCs can be filtered out (at least I think) with a baking soda filter ...those have to be changed more often than the HEPA filters (at least on my model that has one). Again, that should help with some scents (a major issue for me - even the dishwasher running can cause problems for me), but it isn't going to help if there is a gas leak (not sure if that is what the article is suggesting).
> but I also think the extreme results from this study aren't going to hold up to further research.
there already is further research. and the results do seem to be holding up.
the study you're quoting from is the one linked in the 2nd paragraph of the article. this is from the 3rd paragraph:
> But it’s consistent with a growing literature on the cognitive impact of air pollution, which finds that everyone from chess players to baseball umpires to workers in a pear-packing factory suffer deteriorations in performance when the air is more polluted.
that paragraph links to an earlier Vox article [0] which goes into more detail, and well as linking to all of the various studies:
> A wide range of studies about the impact of pollution on cognitive functioning have been published in recent years, showing impacts across a strikingly wide range of endeavors. Stripe CEO Patrick Collison has taken an interest in this subject and compiled much of the key research on his personal blog. Among the findings he’s highlighted include:
> - Exposure to fine particulates over the long term leads to increased incidences of dementia and Alzheimer’s disease in the elderly (a second study confirms this).
> - A study of 20,000 older women found that 10 micrograms of additional long-term particulate exposure is equivalent, across the board, to about two additional years of aging.
> - The impacts are not limited to the elderly, however, nor are they exclusively long-term. A range of specialized professionals also seem to suffer short-term impairment due to air pollution. Skilled chess players, for example, make more mistakes on more polluted days. Baseball umpires are also more likely to make erroneous calls on days with poor air quality. Politicians’ statements become less verbally complex on high-pollution days, too.
> - Ordinary office workers also exhibit these impacts, showing higher scores on cognitive tests when working in low-pollution ( or “green”) office environments. Individual stock traders become less productive on high-pollution days.
> - The same also appears to be true for blue collar work. A study of a pear-packing factory found that higher levels of outdoor particulate pollution “leads to a statistically and economically significant decrease in packing speeds inside the factory, with effects arising at levels well below current air quality standards.”
> - Last but by no means least, the cognitive impacts appear to be present in children, with a Georgia study that looked at retrofits of school buses showing large increases in English test scores and smaller ones in math driven by reduced exposure to diesel emissions.
IQ has about a 0.2 correlation with income. The paradox arises when you zoom out for a more macro view. National IQ has about a 0.6-0.8 correlation with GDP per capita.
Performance in class rooms is definitely an IQ thing and different view points will likely generate different sets of data.
I'm interested in seeing controlled trials on individual performance, not just observing real world scenarios.
One problem with nutrition based science is it suffers from nutrigenomics bias. It’s possible to study small cohorts of similar genetics and come to conclusions which fail to extrapolate to larger populations.
It’s possible that this same problem does not apply to air filtration.
It also seems possible that students do better on tests when the air is cleaner, but that doesn't necessarily mean the students learned more.
Imagine if some schools installed air conditioning in their gym one year. Running times around an indoor track would improve considerably, but mostly because conditions at the point of testing improved. Not necessarily because the air conditioning made the students actually improve their stamina or speed.
> but expecting test scores to improve dramatically like this is not realistic
That seems like a problem for the reader, not a problem with the text. Why would the reader expect this? Is it the use of present tense in the title rather than past tense?
> The whole thing is driven by one data point and a linear trend which makes no theoretical sense in the context of the paper (from the abstract: “Air testing conducted inside schools during the leak (but before air filters were installed) showed no presence of natural gas pollutants, implying that the effectiveness of air filters came from removing common air pollutants”) but does serve to create a background trend to allow a big discontinuity with some statistical significance.
My beef with Matt Y.’s worldview of “scientifically driven public policy” is that the costs and benefits of public policy interventions are so devilishly difficult to study that you can’t meaningfully use them on realistic time scales to drive policy. This is an exceedingly simple hypothesis—filtering air improves test scores—that can easily be tested while controlling for confounding factors. But even then it’s hard!
Andrew Gelman: "No, I don’t think that this study offers good evidence that installing air filters in classrooms has surprisingly large educational benefits."
https://statmodeling.stat.columbia.edu/2020/01/09/no-i-dont-... (Adding this older link here for cross reference)
The study itself is pretty explicit that it is just one encouraging case study which the authors believe merits follow-up research, rather than something conclusive. Matt Y's reporting isn't as forthcoming about this as it probably should've been, but he does also say the same thing at the end. He sort of buried the lede but didn't lie or anything.
I wish there was more data on the effects of gasses in the air on people.
We seem to know:
- Elevated CO2 in rooms impairs cognitive performance.
- Elevated CO2 in submarines, at levels far higher than you would see in a normal room does not appear to impact cognitive performance.
- Installing carbon filters (what this study actually looked at) might improve classroom performance.
- People don’t like stuffy rooms.
All this is consistent with multiple hypotheses. It could be that we just don’t know anything about it. Or maybe there is some gas or gasses emitted by people that isn’t CO2 that makes people mildly uncomfortable and have worse cognitive performance.
CO2 is certainly a good proxy for ventilation quality in a space where air is exchanged with outdoors but where the gasses in the air are not otherwise changed. Carbon-filtered classrooms and submarines are not examples of this.
Elevated CO2 in submarines absolutely impairs performance. One example: there was a guy on my boat who got migraines when CO2 got too high - he was useless. Luckily the fix is simple - just turn on another CO2 scrubber.
There's nothing special about a submarine that makes CO2 somehow different than anywhere else.
CO2 is a proxy for many other gasses. Cheap CO2 sensors sense volatile organic compounds (VOCs), and use those to estimate CO2.
Many of those gasses do impact cognitive performance. It's not obvious to me why CO2 would, but if CO2 is going up, so is everything else we breathe out. CO2 where I am is somewhere in the ≈400ppm-1000ppm range -- 0.04% or 0.1% -- and it's pretty inert. I'm not sure what harm it does.
If it does to harm, rising CO2 levels should be much more concerning than "just" climate change.
I’m so confused why they installed HEPA filters to filter out LNG and methane.
And HEPA filters don’t really scrub CO2 that effectively, even with a carbon membrane, so can we really expect lower CO2 levels?
Considering this, what’s the actual takeaway here? Cleaner air (dust/virus free?) is better for productivity?
I am asking because I want to buy the same filter for work, but I am doubtful that the $700 HEPA filter sounds like the same filter they used, even though the article mentions they used readily accessible 5 stage filters.
Having tried to dig into this a while ago, they installed carbon filters.
Most of the stuff for sale as “carbon” filters has too little carbon to do much. You want quite a lot, and, for some gasses, you can get special impregnated carbon or other media.
I'm guessing someone had a hunch and wanted to buy some HEPA filters. Also, all HEPA filters should filter air similarly, the price should be based on the rate at which air is filtered. I bought a HEPA air filter for $150 for my room.
Personal anecdote getting an airthings that reminds me to open the window (along with a pushover api setup) has probably been the biggest productivity improvement in 10 years.
It's kinda worrying you need an app / appliance to remember to open the window. Rule of thumb is to have the windows open at least 10 minutes a day, every day.
>For a sense of scale, Mathematica Policy Research’s best evidence on the effectiveness of the highly touted KIPP charter school network finds that after three years at KIPP there is significant improvement on three out of four test metrics — up 0.25 standard deviations on one English test, 0.22 standard deviations on another, and 0.28 standard deviations on one of two math tests.
I wasn't sure what .22 std deviations meant, so I looked stuff up a bit. For a normal distribution, going from the average to 1 standard deviation above is going from the 50th percentile to the 84th percentile. Going up .22 standard deviations from the average is going from the 50th percentile to about the 55th percentile.
My dad made a similar observation, assuming the children were young. However, upon reviewing the article, I noticed it doesn’t explicitly mention the grade level. Considering younger children have weaker immune systems, this could potentially lead to fewer missed classes and improved grades. Personally, my first grader misses out on a considerable number of classes.
However, if these results were observed in grades 3 or higher, it could suggest a more substantial phenomenon. I randomly picked the third grade, but perhaps there’s a specific age after which the medical community considers a child’s immunity to be significantly enhanced.
Anecdote: Our daycare was a plague ship right after covid 'ended'. None of the kids had any immunities, and they made up for it in a hurry. Man, what a terrible year.
As a result, the daycare got a grant to get N-95 air filters installed and those UV lights that Chinese restaurants tend to have in the bathrooms. One per room.
What. A. Difference.
The infants and kids coming up are not nearly as sick, and when they do get sick, it's not nearly as terrible. The RSV vaccine has also been a godsend.
I can't really tell/feel what what the silver bullet here, but the combinations have been amazing. So much so that we got them for the house.
I wonder how much of the improvement was due to reversion to the mean. When bringing everyone back, you would expect a sharp peak of infections which would decay to normal levels after a while - filters or not. I'm sure they do still have some positive effect though.
What lights are you talking about? UV capable of disinfecting isn't something you want to be looking at. (Are you perhaps thinking of the bug-zapper lamps that are sometimes described as UV? Way up at the top of the visual spectrum, a lot of bugs go for them. But they're just a lure to get the bug between the high voltage wires that actually kill it.)
The only disinfecting UV lights I've heard of for use in occupied areas are hanging things that only point up where nobody's going to be exposed. I have heard of some research for safe UV lights that are high up in the UV, they actually still burn but without enough penetration to get through the dead skin layer.
Nice story. I can believe it. I was surprised that you mentioned the RSV vaccine. Last I checked, they were still working on it. I was wrong: There are three competitors now: (1) Arexvy (GSK), (2) Abrysvo (Pfizer), and (3) Mresvia (Moderna)
In studies of pollution and impacts on health, the confounding factors often have a larger impact on the health outcome than the pollutant, such as particulate level, and therefore significant control of confounders is required to estimate any impact on the health outcome. The strong effect in this study is highly suggestive of a confounder rather than a real effect from particles or other pollutants and therefore would require a much better study design to support tacking action at a policy level with an expectation of a huge impact.
Fine to put filters into improve overall air quality but just not with the benefit rationale suggested in this study.
Only marginally relevant, this is one reason I use swamp coolers in my home. My windows are open 24/7, 4 months of the year. I hear the birds in the morning and it’s so much more pleasant than shutting in an air conditioned box, in my opinion
Many air filters are generating annoying sounds. You get better air, but the distraction by the constant noise of the filter might be more than counter productive.
My first thought was the exact opposite. Ambient noise in classroom (from other students) can be very distracting, and I wonder if adding white noise helps kids to focus (in the same way that accoustic dampening would)
A study published just yesterday [1] showed that just two airborne diseases [2] were responsible for approximately 85% of all sicks days in Greece during 2023-2024. Disregarding the common-sense argument that reducing collective suffering is a good thing overall - even by the cold hard logic of capital, being able to reduce company sick days by up to 85% is a huge opportunity.
Imo we're way overdue standards and controls for clean indoor air that are on par with standards for drinking water and food. Like this article shows, we have the tech to provide clean air today. All we're missing is policy to uniformly deploy it.
Might this be related to the fact that Greeks tend not to take sick days compared to other European countries[1]? Not coming to work because you have covid is far more culturally accepted (and maybe expected) than a common cold.
Does anyone have any details on what kind of filter this was? I bought a relatively high-MERV filter for my home, but I’m wondering what I should actually be trying to filter out.
MERV 13's are optimal for particle removal because compared to a HEPA some of the removal requires multiple passes but the filters are a lot less restrictive and allow higher airflow. Corsi and Rosenthal looked into this with the CR box and came to the conclusion its technically faster at clearing a room than using HEPA standard filters. For infections and damaging PM2.5 particles mechanical filtration with MERV13 is the best you are going to get.
You could also add potentially get a HEPA with a carbon filter which will get rid of volatile organic compounds which can also be damaging (but also just be the smell of food) but they don't tend to be as effective and depending on the mix of VOCs verses particles one filter may run out before the other and carbon really doesn't capture all that much or well. It is a good way to get rid of smell at least for a while.
There is a whole world of different standards for filtration for industrial and hazard chemicals which the FFP2/3 and N95 standards for Personal Protective Equipment respirators will lead you into if you want to go into that rabbit hole, but for a household typically its mostlt about Particulate matter, Volatile organic compounds and CO2. CO2 is about bringing in fresh air from outside.
Then when outside of the household N95/99 or FFP2/3 respitators do the same job in unclean air environments which is basically everywhere, outside or indoors in public places pretty much never meet the World Health Organisations levels for PM2.5 and often exceed CO2 (a proxy for re-breathing and a high change of viral infection spread) standards too.
I didn't see the model specified. They also said some schools got carbon filters, which is a different type of filter.
There's footnote saying many filters weren't even installed because some teachers thought they made the air "too dry", which is major placebo effect at work (air purifiers don't extract moisture from the air).
The entire paper is really not good quality, to be honest.
You can get a small HEPA purifier for a single room to remove particulates. The size of the filter, noise level, and amount of air moved are things to look for. Stepping up to activated carbon would remove VOCs, but cost significantly more (see IQAir, Austin Air, but ignore the cheap models that don't have 10-20lbs or more of activated carbon).
Higher does not necessarily mean better. Higher grade filters filter more in each pass, but can overall provide worse performance as the air flow rate goes down. The air is being recirculated in a portable unit or in a standard domestic ducted heating/cooling situation.
There have been some classroom studies in the UK showing a reduction in illness as well. They were a bit better run than this because they had some some pupils in filtered air and some not and even with the mixing at break time the reduction of illness met clinical significance. Given Covid is doing its thing all year around its quite an easy thing to do to drastically reduce the time teachers and pupils spend away from school and its a fairly easy measure to adopt. They do need to have the filters running however and that will involve explaining to the teachers how they work and why they are needed because in a lot of studies compliance has been a big issue usually due to misinformation rather than issues with the devices.
I wonder how smart I’d be if I didn’t sit in a classroom full of metal tables that got painted with such a thick layer of oil paint that it stunk of paint thinner until Spring
Yeah, I got driven out of college by one bad building. (This was back before it was understood that a building can be a problem.) I simply couldn't think properly while in it. A problem with classes, a showstopper when the labs were in the building. I'm sure I would have flunked out if I had tried to take those classes. I have no idea what I was reacting to but there sure was something. (It felt a lot like one house where I had the same sense of something bad walking in the door--and long later a wall full of black mold was discovered.)
Given that SARS2 affects cognition negatively, I would expect schools with universal air filtration to have larger improvements than we would have expected prior.
Now let's see if the filters are not changed in a while, and how that effects the studies (not on purpose, I'm guessing that the upkeep is not very good with filters in general)
Aurornis|11 months ago
From the paper:
> To do so, I leverage a unique setting arising from the largest gas leak in United States history, whereby the offending gas company installed air filters in every classroom, office and common area for all schools within five miles of the leak (but not beyond). This variation allows me to compare student achievement in schools receiving air filters relative to those that did not using a spatial regression discontinuity design.
In other words, the paper looked at test scores at different schools in different areas on different years and assumed that the only change was the air filters. Anyone who has worked with school kids knows that the variations between classes from year to year can be extreme, as can differences produced by different teachers or even school policies.
Again, I think air filtration is great indoors, but expecting test scores to improve dramatically like this is not realistic. This feels like another extremely exaggerated health claim, like past claims made about fish oil supplements. Fish oil was briefly thought to have extreme positive health benefits from a number of very small studies like this, but as sample sizes became larger and studies became higher quality, most of the beneficial effects disappeared.
AngryData|11 months ago
To me its like looking at schools that buy newer buses and trying to show new buses improve test scores. When in practice the only schools that are buying any significant number of new buses have far more money coming in than in the past and have a lot more to spend on students compared to other schools, which is way more relevant than what year a kid's bus is made. Maybe better buses would improve scores too, but there is no way to tell if 95% of an improvement is due to other unrelated factors based on funding.
stdbrouw|11 months ago
The smoking gun is really in Table 3 and Table 4, where you can see that the effects that were observed are compatible with a population effect of 0, or alternatively you can look at Figure 2 and note that you could draw a straight line (no effect) within the confidence bands. Doesn't mean the effect is not there, but that there's insufficient evidence that it is, and that we should indeed be very careful about taking the estimates at face value.
mmooss|11 months ago
All research is met on HN by people who know better and will tell you why it's flawed. There isn't a greater collection of expertise in the history of the world than on HN.
Edit: I meant to add: What value can we find in this research? It wasn't published as scripture, the perfect answer to all our problems. It's one study of some interesting events and data; what can we get out of it?
MPSFounder|11 months ago
d--b|11 months ago
Maybe the tests results are better because the children are more rested on the day of the test. Maybe the hum of the machine creates some kind of meditative noise that helps children concentrate. Or maybe none of that is true..
7thaccount|11 months ago
evil-olive|11 months ago
there already is further research. and the results do seem to be holding up.
the study you're quoting from is the one linked in the 2nd paragraph of the article. this is from the 3rd paragraph:
> But it’s consistent with a growing literature on the cognitive impact of air pollution, which finds that everyone from chess players to baseball umpires to workers in a pear-packing factory suffer deteriorations in performance when the air is more polluted.
that paragraph links to an earlier Vox article [0] which goes into more detail, and well as linking to all of the various studies:
> A wide range of studies about the impact of pollution on cognitive functioning have been published in recent years, showing impacts across a strikingly wide range of endeavors. Stripe CEO Patrick Collison has taken an interest in this subject and compiled much of the key research on his personal blog. Among the findings he’s highlighted include:
> - Exposure to fine particulates over the long term leads to increased incidences of dementia and Alzheimer’s disease in the elderly (a second study confirms this).
> - A study of 20,000 older women found that 10 micrograms of additional long-term particulate exposure is equivalent, across the board, to about two additional years of aging.
> - The impacts are not limited to the elderly, however, nor are they exclusively long-term. A range of specialized professionals also seem to suffer short-term impairment due to air pollution. Skilled chess players, for example, make more mistakes on more polluted days. Baseball umpires are also more likely to make erroneous calls on days with poor air quality. Politicians’ statements become less verbally complex on high-pollution days, too.
> - Ordinary office workers also exhibit these impacts, showing higher scores on cognitive tests when working in low-pollution ( or “green”) office environments. Individual stock traders become less productive on high-pollution days.
> - The same also appears to be true for blue collar work. A study of a pear-packing factory found that higher levels of outdoor particulate pollution “leads to a statistically and economically significant decrease in packing speeds inside the factory, with effects arising at levels well below current air quality standards.”
> - Last but by no means least, the cognitive impacts appear to be present in children, with a Georgia study that looked at retrofits of school buses showing large increases in English test scores and smaller ones in math driven by reduced exposure to diesel emissions.
0: https://www.vox.com/future-perfect/2019/12/11/20996968/air-p...
xattt|11 months ago
dzhiurgis|11 months ago
ninetyninenine|11 months ago
IQ has about a 0.2 correlation with income. The paradox arises when you zoom out for a more macro view. National IQ has about a 0.6-0.8 correlation with GDP per capita.
Performance in class rooms is definitely an IQ thing and different view points will likely generate different sets of data.
I'm interested in seeing controlled trials on individual performance, not just observing real world scenarios.
VladVladikoff|11 months ago
fasthands9|11 months ago
Imagine if some schools installed air conditioning in their gym one year. Running times around an indoor track would improve considerably, but mostly because conditions at the point of testing improved. Not necessarily because the air conditioning made the students actually improve their stamina or speed.
facile3232|11 months ago
That seems like a problem for the reader, not a problem with the text. Why would the reader expect this? Is it the use of present tense in the title rather than past tense?
rayiner|11 months ago
> The whole thing is driven by one data point and a linear trend which makes no theoretical sense in the context of the paper (from the abstract: “Air testing conducted inside schools during the leak (but before air filters were installed) showed no presence of natural gas pollutants, implying that the effectiveness of air filters came from removing common air pollutants”) but does serve to create a background trend to allow a big discontinuity with some statistical significance.
I’m reminded of the walkback of scientific studies showing massive benefits from giving kids in third world countries deworming medications: https://www.theguardian.com/society/2015/jul/23/research-glo....
My beef with Matt Y.’s worldview of “scientifically driven public policy” is that the costs and benefits of public policy interventions are so devilishly difficult to study that you can’t meaningfully use them on realistic time scales to drive policy. This is an exceedingly simple hypothesis—filtering air improves test scores—that can easily be tested while controlling for confounding factors. But even then it’s hard!
rnjailamba|11 months ago
A thread on Gelman's article is here: https://news.ycombinator.com/item?id=22006595.
Analemma_|11 months ago
sudoshred|11 months ago
amluto|11 months ago
We seem to know:
- Elevated CO2 in rooms impairs cognitive performance.
- Elevated CO2 in submarines, at levels far higher than you would see in a normal room does not appear to impact cognitive performance.
- Installing carbon filters (what this study actually looked at) might improve classroom performance.
- People don’t like stuffy rooms.
All this is consistent with multiple hypotheses. It could be that we just don’t know anything about it. Or maybe there is some gas or gasses emitted by people that isn’t CO2 that makes people mildly uncomfortable and have worse cognitive performance.
CO2 is certainly a good proxy for ventilation quality in a space where air is exchanged with outdoors but where the gasses in the air are not otherwise changed. Carbon-filtered classrooms and submarines are not examples of this.
jedc|11 months ago
Elevated CO2 in submarines absolutely impairs performance. One example: there was a guy on my boat who got migraines when CO2 got too high - he was useless. Luckily the fix is simple - just turn on another CO2 scrubber.
There's nothing special about a submarine that makes CO2 somehow different than anywhere else.
frognumber|11 months ago
Many of those gasses do impact cognitive performance. It's not obvious to me why CO2 would, but if CO2 is going up, so is everything else we breathe out. CO2 where I am is somewhere in the ≈400ppm-1000ppm range -- 0.04% or 0.1% -- and it's pretty inert. I'm not sure what harm it does.
If it does to harm, rising CO2 levels should be much more concerning than "just" climate change.
But I suspect it's other gasses.
aetherspawn|11 months ago
And HEPA filters don’t really scrub CO2 that effectively, even with a carbon membrane, so can we really expect lower CO2 levels?
Considering this, what’s the actual takeaway here? Cleaner air (dust/virus free?) is better for productivity?
I am asking because I want to buy the same filter for work, but I am doubtful that the $700 HEPA filter sounds like the same filter they used, even though the article mentions they used readily accessible 5 stage filters.
amluto|11 months ago
Most of the stuff for sale as “carbon” filters has too little carbon to do much. You want quite a lot, and, for some gasses, you can get special impregnated carbon or other media.
tangjurine|11 months ago
jwpapi|11 months ago
Cthulhu_|11 months ago
tangjurine|11 months ago
I wasn't sure what .22 std deviations meant, so I looked stuff up a bit. For a normal distribution, going from the average to 1 standard deviation above is going from the 50th percentile to the 84th percentile. Going up .22 standard deviations from the average is going from the 50th percentile to about the 55th percentile.
fifteenforty|11 months ago
sheepscreek|11 months ago
However, if these results were observed in grades 3 or higher, it could suggest a more substantial phenomenon. I randomly picked the third grade, but perhaps there’s a specific age after which the medical community considers a child’s immunity to be significantly enhanced.
Balgair|11 months ago
As a result, the daycare got a grant to get N-95 air filters installed and those UV lights that Chinese restaurants tend to have in the bathrooms. One per room.
What. A. Difference.
The infants and kids coming up are not nearly as sick, and when they do get sick, it's not nearly as terrible. The RSV vaccine has also been a godsend.
I can't really tell/feel what what the silver bullet here, but the combinations have been amazing. So much so that we got them for the house.
HPsquared|11 months ago
LorenPechtel|11 months ago
The only disinfecting UV lights I've heard of for use in occupied areas are hanging things that only point up where nobody's going to be exposed. I have heard of some research for safe UV lights that are high up in the UV, they actually still burn but without enough penetration to get through the dead skin layer.
throwaway2037|11 months ago
Ref: https://en.wikipedia.org/wiki/Respiratory_syncytial_virus_va...
Normally, I use this clinic in Thailand to compare prices for vaccines: https://www.thaitravelclinic.com/cost.html
The RSV vaccine is crazy expensive, even more than the HPV one. Over 200 USD is incredibly expensive in a developing country (like Thailand).
I never heard of this. Does anyone have a link to one of these on Amazon or Alibaba? I am curious to learn more.craigdalton|11 months ago
In studies of pollution and impacts on health, the confounding factors often have a larger impact on the health outcome than the pollutant, such as particulate level, and therefore significant control of confounders is required to estimate any impact on the health outcome. The strong effect in this study is highly suggestive of a confounder rather than a real effect from particles or other pollutants and therefore would require a much better study design to support tacking action at a policy level with an expectation of a huge impact.
Fine to put filters into improve overall air quality but just not with the benefit rationale suggested in this study.
theoreticalmal|11 months ago
Mistletoe|11 months ago
meroes|11 months ago
amai|11 months ago
brody_hamer|11 months ago
yoshuaw|11 months ago
Imo we're way overdue standards and controls for clean indoor air that are on par with standards for drinking water and food. Like this article shows, we have the tech to provide clean air today. All we're missing is policy to uniformly deploy it.
[1]: https://www.sciencedirect.com/science/article/abs/pii/S01966...
[2]: SARS-CoV-19: ~75% of sick days, Influenza: ~10% of sick days
socksy|11 months ago
[1]: https://www.ekathimerini.com/economy/1255154/greek-work-ethi...
knotimpressed|11 months ago
PaulKeeble|11 months ago
You could also add potentially get a HEPA with a carbon filter which will get rid of volatile organic compounds which can also be damaging (but also just be the smell of food) but they don't tend to be as effective and depending on the mix of VOCs verses particles one filter may run out before the other and carbon really doesn't capture all that much or well. It is a good way to get rid of smell at least for a while.
There is a whole world of different standards for filtration for industrial and hazard chemicals which the FFP2/3 and N95 standards for Personal Protective Equipment respirators will lead you into if you want to go into that rabbit hole, but for a household typically its mostlt about Particulate matter, Volatile organic compounds and CO2. CO2 is about bringing in fresh air from outside.
Then when outside of the household N95/99 or FFP2/3 respitators do the same job in unclean air environments which is basically everywhere, outside or indoors in public places pretty much never meet the World Health Organisations levels for PM2.5 and often exceed CO2 (a proxy for re-breathing and a high change of viral infection spread) standards too.
Aurornis|11 months ago
I didn't see the model specified. They also said some schools got carbon filters, which is a different type of filter.
There's footnote saying many filters weren't even installed because some teachers thought they made the air "too dry", which is major placebo effect at work (air purifiers don't extract moisture from the air).
The entire paper is really not good quality, to be honest.
You can get a small HEPA purifier for a single room to remove particulates. The size of the filter, noise level, and amount of air moved are things to look for. Stepping up to activated carbon would remove VOCs, but cost significantly more (see IQAir, Austin Air, but ignore the cheap models that don't have 10-20lbs or more of activated carbon).
fifteenforty|11 months ago
dang|11 months ago
A review of the effects of installing air filters in classrooms - https://news.ycombinator.com/item?id=22006595 - Jan 2020 (26 comments)
Installing air filters in classrooms has large educational benefits? - https://news.ycombinator.com/item?id=22006033 - Jan 2020 (48 comments)
PaulKeeble|11 months ago
joeevans1000|11 months ago
culopatin|11 months ago
LorenPechtel|11 months ago
tehjoker|11 months ago
Animats|11 months ago
MemexXx|11 months ago
acstorage|11 months ago
throwaway81523|11 months ago
yimby2001|11 months ago
[deleted]
ribcage|11 months ago
[deleted]
unknown|11 months ago
[deleted]
aaron695|11 months ago
[deleted]
hollerith|11 months ago
Places with clean outdoor air probably won't see much benefit.
sebastiennight|11 months ago