Tangential, but I've had this monitor[0] at home for about 2 years and I can recommend it.
I live in a place that's generally cold for a large part of the year, so I have all windows shut for most of the time. I've discovered that tracking CO_2 levels is a very good proxy for general air quality, and a good measure of both when to open windows and for how long to keep windows open.
For my apartment, I was surprised that the amount of time I needed to keep the windows open was 5x longer than what I initially assumed (I assumed 5 mins would be enough. Data shows that I need about 25 mins to get CO2 levels down to around 500ppm). I was also surprised to see how much more rapidly CO2 builds up when I have just 2 additional people at home.
I use an Awair, also in a cold climate. Seeing the data for my air quality motivated me to install an air exchanger. Having the monitor allowed me to see how much we needed to exchange in order to keep the CO2 at a decent level.
For anyone with a modern home that is sealed up average or better, an air monitor indoors is almost a must.
On the topic of the number of people and CO2, I'm tempted to have it alert me when I'm out of town and the CO2 rises. I have an alarm, but who would think to defeat the innocent looking air monitor on the shelf?
Awair let's you hit the device on the LAN and get JSON, so the software is all mine. You don't have to let it connect out or report to anyone else. That is one of the reasons I picked it, I like my smart home to stay home.
Ha, if only it were that sensitize. I have an air exchanger, so I don't think the plants will change it enough to matter. I expect that normal air infiltration would cycle more air than plants.
Airthings has some good hardware and I like the e-ink display but it has terrible terms of use that severely restrict your ownership rights.
Here are some excerpts from Airthings T&Cs [1] that I find very problematic:
In 15.4. of Airthings T&C it writes: “We own and shall retain ownership of all rights to all data and information collected via the Services provided to you…”
Furthermore, in 15.2 Airthings claims all rights for modifications that you might carry out on the Airthings monitor: “You hereby assign to Airthings all right, title, and interest (including Intellectual Property Rights) that you may have in any custom developments, modifications, or derivative works of the Services and Products created or developed by or for you, including but not limited to design, artwork, technology, software, data, functionality, and documentation.”
I wrote about it in a review with our monitor [2].
> I assumed 5 mins would be enough. Data shows that I need about 25 mins to get CO2 levels down to around 500ppm
I also noticed that just cracking a window doesn't seem to do much according to the CO2 monitor, except letting the heat escape.
The trick is to open multiple windows/doors wide and get some cross ventilation going. This gets CO2 down in only a few minutes. It's called stoßlüften in German.
Way too expensive for a device like that, at $300. They usually go for $10-20 at Aliexpress.com. But it has rounded corners, so I guess suits the Americans.
In addition to measuring VOCs, specifically alcohols, instead of CO2 using NDIR, the cheap ones can have additional algorithms that skew the readings.
I purchased an INKBIRD Air Pollution Monitor. It has an internal battery, doesn't connect to other devices or networks, is inexpensive, and is irrationally inaccurate sometimes.
A reviewer found the same behaviour and confirmed what I knew through tests with dry ice (solid CO2) and isopropanol alcohol. It measures CO2, not VOCs, but some constantly running calibration or data fitting algorithms lead to wild overshoot and undershooting compared to higher-quality monitors.
Finding an inexpensive and accurate CO2 monitor may be possible, and aliexpress.com is the home of inexpensive. But without testing and possibly a teardown, you will not likely get an accurate and affordable monitor.
Getting sleepy, getting a headache, performing worse physically and mentally. Might be more stuff if you look into it, but to me this is the obvious stuff that matters and already justifies frequently opening windows.
I have several CO2 monitors including some from AirThings, Aranet4, and a industrial sensor in the form of a Vaisala GMP252 CO2 probe. They all track closely enough that I don't worry about it.
The Vaisala is rated to +/- 40PPM which is accurate enough for living space environmentals.
I don't have any equipment to calibrate it or measure it's calibration against. However, when I leave the windows open for extended periods of time, the CO2 levels hit levels that are within 50ppm of [0]. (I live in a different city from this station, with different population density, traffic patterns and all sorts of other micro-climate stuff that can contribute to a baseline difference. Additionally, CO2 levels swing by several hundred ppm when the air quality goes bad, and the ~50ppm range is insignificant in comparison)
It seems good enough for how I use it. I wouldn't conduct chemistry experiments using this as an instrument.
All these devices calibrate by periodically measuring the lowest ppm in a given period, and assigning it a value of 420. That's how they always accurately measure CO2 with the windows open.
Title seems misleading. It seems that they have results that elevated levels of CO2 in the air increase survivability of viral aerosol particles and infectiousness. Since CO2 is so low (400-1000ppm) this is surprising. Haven't had time to look through the paper closely but seems to be pH related which makes sense.
Air isn't a liquid, but the virus is contained within a tiny bubble of water as I understand it.
Atmospheric CO2 change acidifying the oceans is a well known effect [1]. Once it's pointed out it isn't surprising that a tiny bubble of water surrounded by atmosphere would change PH quickly in response to atmospheric CO2 levels (the surface area to volume ratio is huge compared to the ocean after all). Nor that that affects viruses.
> In its call to action, the group proposed CO2 as one of three key metrics, suggesting ventilation rates that would keep CO2 levels at 800 parts per million or below.
Pre-industrial CO2 levels were at 280ppm, currently we have 420ppm, rising & accelerating. Give it three or four decades and ventilation won't help anymore.
> Pre-industrial CO2 levels were at 280ppm, currently we have 480ppm, rising & accelerating. Give it three or four decades and ventilation won't help anymore
400 ppm: average outdoor air level.
400–1,000 ppm: typical level found in occupied spaces with good air exchange.
1,000–2,000 ppm: level associated with complaints of drowsiness and poor air.
2,000–5,000 ppm: level associated with headaches, sleepiness, and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be present.
5,000 ppm: this indicates unusual air conditions where high levels of other gases could also be present. Toxicity or oxygen deprivation could occur. This is the permissible exposure limit for daily workplace exposures.
40,000 ppm: this level is immediately harmful due to oxygen deprivation.
Thanks for linking that! Will be hunting a bit for any recent takes on these studies.
I'm finding I can't really tell any difference in mood/alertness/whatever despite what my sensor thing reports. To the point that I don't know why I bother keeping this thing in the office.
It is only in my office that the values get high. Rest of the house is fine.
My suspicion is these devices just can't really tell you much about how localized the readings are. And comparing a number for a large room to a converted closet is not at all meaningful.
Those levels are absurd. The optimal level is the pre-industrial level of under 300 ppm which is what humans evolved under for millennia. The levels outdoors are closer to 500 now than to 400. Drowsiness starts at levels as low as 600-800.
Plant photosynthesis has its upper limits. So, self modulating to an extent.
I think the article is more insightful around I indoor air quality rather than outdoor. With respect to outdoor, if CO2 were fully self modulating, isn't the fact it has been consistently raising a counter point to that idea? How does self modulation explain the data showing increases?
Do you believe in the flat earth too? CO2 has risen in front of my eyes in my lifetime from 350 to 420. It most certainly is not self-modulating. Oxygen isn't either, as it slowly escapes into space.
Believe it or not the standard is to report the CO2 level measured at the top of an active volcano (Mauna Loa). This is for historical reasons, because it's where the first measurements were taken, but also they claim it's more accurate because the measurement site is surrounded by miles of lava and thus there's no trees or vegetation which could absorb CO2 locally nor any human settlements that could emit CO2.
There is of course the small problem of it being a volcano. Other measurements come from a collection of sensors on TV or telecom towers. Some of them come from planes.
The trend is the same in every site, although absolute readings vary somewhat. There are cleaner sites than Mauna Loa, like in Antarctica, but those show about 10ppm lower. Others give the same reading as at Mauna Loa but with more seasonal variance. It's unclear whether these differences really matter and they tend to be ignored.
How did we measure CO2 accurately pre-industry? Isn't the rise of industry kind of coincident with the ability to measure gases accurately? And if the trend as accuracy increased was up, wouldn't it suggest initial underestimates?
Or is there some reliable way we can measure in retrospect?
Thanks, though that study makes no mention of CO2, and concerns instead oxygen from 500m, to 1b years ago, which seems a little far off to be applicable to the order of the around one hundred and fifty years ago being asked about. Have I missed something?
My comment only explains how it's done. I'm sure you can understand that the article I mentioned was just an example. If you're looking for a specific CO2 measurement from air captured exactly one hundred and fifty years ago, I'll leave you to Google that yourself.
Everything else I found was unfortunately hand-wavy "scientific consensus says" and the ubiquitous "280ppm" coupled with "pre-industrial" repeated again without reference, nor apparent empirical basis.
Not convincing, which for "the science is settled" I'd expect a bit of a higher standard.
CO2 levels are increasing at ~3ppm/year*. In 40 years we're looking at roughly 120ppm. Noticeable but not "we're all going to have headaches and covid" numbers.
I mean we might all have headaches and covid, but not directly because of CO2 at outdoor concentrations.
* 2.8ppm in 2022-2023, the rate at which CO2 is increasing is very slowly increasing but it's close enough to constant for rough calculations, especially after rounding up to 3.
The rate is increasing, it is not constant. It used to be 1ppm per year. So it will be not 120ppm extra, it will be more. It might appear not much but when you consider indoor air then when currently room stayed below the recommended CO2 limit, it maybe now be above of it or you need more air changes that will require more energy (to move air and to condition it). And while 120ppm in 40 years might appear not a lot then you should also consider that 40 years is actually very short time - in 120 years it will be about twice as today - there would be no fresh air anymore.
So it sounds like the climate change problem will be solved before too long, if the rate continues to increase. According to another post above, CO2 levels above 40,000 ppm are "immediately harmful" (I read that as lethal), while levels above 5,000 cause oxygen deprivation. So, when there's too much CO2 in the atmosphere because stupid humans refuse to stop driving giant SUVs, the air itself will prevent humans from even functioning mentally, human society will collapse, and the human population will quickly fall.
Society would be greatly impacted at far lower levels (anywhere from really current levels and up). See my other reply to peer comment.
Though... 40k ppm is talking extinction of all mammals, probably more. The greenhouse effect at that level is probably insane, I wonder if we might lose liquid water well before that point.
Perhaps not that high. Regardless, entering that period was marked by a mass extinction.*
This source [0] states it well:
"The end-Permian mass extinction, the largest biological crisis in Earth history, is currently understood in the context of Siberian Traps volcanism introducing large quantities of greenhouse gases to the atmosphere, culminating in the Early Triassic hothouse. In our study, the late Permian and Early Triassic atmospheric CO2 history was reconstructed by applying the paleosol pCO2 barometer. Atmospheric pCO2 shows an approximate 4× increase from mean concentrations of 412–919 ppmv in the late Permian (Changhsingian) to maximum levels between 2181 and 2610 ppmv in the Early Triassic (late Griesbachian)."
* looks like we can quibble on 2k ppm or 5k ppm, the salient part is the global mass extinction part. Whether that was a correlation or caused by CO2 is not defined, at any rate it is not really speaking to a very habitable earth for humans.
At 1300 ppm strato-cumulus clouds can no longer form. [0] Losing those is a +8C temperature increase alone. [0]
At that approx +3ppm/yr, it would be about 300 years before we are there. Which is about 10 human generations, which is roughly the grandchildren of your grandchildren's grandchildren.
At +8 on top of wherever the temp is then, my understanding is that is effectively talking runaway greenhouse effect and a hothouse earth.
To make it more grim, the ocean has been acting as a carbon dioxide and heat sponge, and is possibly getting saturated. The rate of human emission increases is only starting to level (still increasing though [going from recollection, please correct me if wrong]). And to make things even more grim, that is still not counting other feedback loops like permafrost melting and boreal forests burning.
Yes, it's impractically high: we exhale about 1kg of carbon daily, so your plants collectively need to be getting about 1kg heavier daily to absorb that.
It's an order of magnitude worse than that, plants are mostly water, not carbon. They'll gain tens of kilos per day.
If you can feed off your house plants alone, then you have a chance of closing the carbon loop. This was tried (e.g. biosphere2) and it's extremely hard even at the industrial scale.
People don’t need to eat 10’s of kilos of plants per day which should suggest your off by an order of magnitude.
Chemistry means converting 1kg of CO2 > O2 would mean removing ~273 grams of carbon. Hydrogen and Wet vs dry weight more than offsets this, but you’re at closer to 2kg than tens of kilos.
This still assumes an air tight system where people never leave home, so plants can make a difference long before they are a 1:1 replacement.
I don't know what portion of a typical plants mass is carbon, and your 273 grams of carbon number is right (the 1kg number is CO2), but I don't think "people don't need to eat 10's of kilos of plants per day" actually justifies your claim about their density or invalidates GPs claim as to how much plant-mass you need to offset what you eat.
We don't just eat random (average) parts of plants, we eat selected ones, primarily things like fruits and bulbs that plants store energy in. If you just tried to eat, say, lettuce... at 2000 calories per day you would need roughly 14kgs [1, 2]. Which is surprisingly close to GPs 10s of kg number all things considered.
Either way, growing 2kg of plant/day or 20kg of plant/day... seems impractical to me. There's also the issue that if you equalize CO2 levels with the outdoors during the day as you open doors and windows, you're going to make night worse as both you and the plants output CO2 during the night.
> We don’t just eat random (average) parts of plants, we eat selected ones
We can’t digest cellulose which throws off the calculations based on what calories are available to us. The question was the minimums not the worst case. Obviously most carbon sequestered by trees isn’t available to us a calories.
In a closed environment simply eating plants wouldn’t result in the correct carbon balance long term. We would need to breakdown our waste via microbes, fungi, or burning.
Yeah it was sort of a joke, but having houseplants will make some difference. Not that they would be practical to absorb all the CO2 in the air. On the downside, keeping indoor plants healthy does take some ongoing time and effort and isn't everyone's cup of tea.
this ignores "system balance" and assumes "closed system" no? In other words, no one says that plants alone will compensate.. but instead they tip a system in a more favorable direction.. Plus some people really respond to house plants in lots of complimentary positive ways.
When plants remove CO2 and release O2, they have to do something with that carbon atom. They can use it to make sap or fruit, but mostly they use it to build more plant.
A plant that isn't growing, like, a LOT, can't possibly be removing much CO2.
The soil itself is also storing CO2, in a variety of different less than intuitive processes. The most obvious is when parts of the plant die and breakdown into the soil itself.
This is true, but mostly because the cost of bring in external air is near $0 in most cases - just open a few windows! But there's a lot of absurdly cool ways to scrub CO2 that are not especially expensive, like the video-game level of serendipity+convenience that's the Sabatier Reaction [1]. Combine hydrogen + CO2 at 300C => methane + water.
It's already being used on the ISS to keep the air fresh. It'll also be a key component on Mars. There you have basically unlimited CO2 and unlimited hydrogen which yields unlimited methane and unlimited water. Carry out electrolysis on some of the water and you get hydrogen + oxygen. The hydrogen can be fed back into the original cycle, and so you end up left with methane + oxygen which is also known as rocket fuel, uncoincidentally the exact sort SpaceX's Starship is using.
Back on Earth you could use this reaction to create practically endless carbon neutral fuel so long as the CO2 was sourced from either the air or a regrown natural capture source like trees or what not. Rockets using this fuel would even have a negative carbon footprint since some of that fuel will get burnt outside the atmosphere. It all seriously feels like a video game where there's just this perfect, but just utterly contrived, rule allowing you to thrive on the next level of difficulty.
The Sabatier reaction is completely safe. Here [1] is a video of a few kids doing it completely manually with a couple of syringes, a pipe, and a torch. Producing methane is one of the huge benefits. Methane is just a normal fuel - use it to generate electricity, for your oven/stove, heating, whatever. But at home if all you want is CO2 removal then just use some lye, soda lime, or a million other simple capture technologies. Not quite as sexy, but it'll get the job done.
<rant> There's no grand technologies required for any of these things. The only reason it's not done at scale is the same reason we can't have nice things in general. Governments are far more interested in war and cock measuring contests than actually solving problems. We spent literally trillions of dollars on Iraq and Afghanistan, and the latest wars will probably dwarf that. Just imagine all the crazy sci-fi scale of things we could have done with all that money. Alas, humanity seems to be running on loop, except now we have nukes, paired alongside what are likely some of the most idiotic 'leaders' in centuries. Want to know the answer to the Fermi Paradox? </rant>
Well said. The root cause as I see it is the nature of money used by the people. If money were gold or bitcoin or a similar limited commodity, with a sufficient layer of anonymization, also with global validity and use, then many of these problems would not happen because the governments just would not have so much money to waste. The governments use their guns to enforce that we use their money instead which is prone to heavy inflation and excessive taxation. Reasonable taxation can still exist even with gold/bitcoin via property taxes. We do not have financial freedom.
Definitely. Filtering particulates and tempering the outside air is the way to go in anything but most extreme situations. I suspect even designing a fallout shelter you would want to go that route.
Navies have been removing CO2 from submarines for decades. I think they use sodium hydroxide.
Manned space programs must remove CO2 air breathed by astronauts. They used lithium hydroxide for decades (including famously in Apollo 13) but ISTR the international space station has a more sophisticated process.
The ISS has a clever trick of using zeolite beds to absorb CO2 (a rock with pores that selectively hold onto CO2, and H2O but they dry the air first), and then venting it to space to get rid of the CO2 and recharge them.
How is that new information "challenging old ventilation doctrine"? It confirms old ventilation doctrine: monitoring CO2 remains a good proxy for general air quality, including viral and bacterial threats, and reducing CO2 via ventilation reduces other threats. That's doctrine, and now it has stronger evidence to support it, and another possible explanation for why and how well CO2 is correlated with other air quality issues.
Ventilation good. CO2 bad. No challenge to old ventilation doctrine detected. (The article and the research seems much more nuanced than the silly title.)
The old doctrine was that CO2 was a proxy for air quality, and the (somewhat overblown title) is about seeing CO2 additionally as having a causal effect.
For example, under the "proxy" model, if you're worried about infection risk it's sufficient to filter the air, but under the new model filtering will work less well than you'd expect because the viruses you miss will stay active longer.
"The old doctrine was that CO2 was a proxy for air quality"
That's not accurate, though. CO2 is, on its own, an air quality concern.
It has also been known, or at least part of the conversation, since Florence Nightingale's time, that fresh air reduces infections (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9300299/). This research makes a small tweak to our understanding, but it's also something that's been suspected/suggested by others for decades.
This research isn't "challenging" anything, it's merely expanding our understanding of causation about previously observed correlations. It's good to know what's happening. It's silly to make it out to be something it's not.
Listen. You don't get tenure confirming centuries-known ideas. You get it upending known doctrines. So if your research doesn't upend the doctrine, find a way to make your title say it does
One way it challenges old doctrine is that 1000ppm CO2 was considered good air quality in the past. Now it seems 800ppm or perhaps lower should be considered good air quality. They haven't tested other viruses yet (both colds and flu viruses are now considered airborne I understand, and other respiratory viruses probably are also), and each virus may react differently, so nobody actually knows yet what an optimal value is. It is even possible that the optimal CO2 value is somewhere below the current average concentration of CO2 in the air around the world when taking all airborne viruses into consideration, but nobody knows. More research is needed. But at least for covid, 1000ppm CO2 should probably no longer be considered good air quality (though replication of the study would be good.)
If supermarkets and other public spaces had installed CO2 scrubbers on their ventilation output/exhaust, could we have expected to lower COVID's r-naught?
In what we did over the pandemic with masking, we drove some flu variants extinct. Is this an alternative to accomplish the same effect?
Are hospitals already doing this with existing ventilation?
CO2 scrubbers don't exist in an economically feasible form. Rather the trick is just ventilation, replace indoor air with ourdoor air. If supermarkets and other public spaces just installed ventilation systems that exchanged their indoor air with outdoors air (preferably with heat exchanges so as to avoid air-conditioning or heating the outdoors), it would absolutely have helped. Ignoring this very interesting study, ventilation still just flat out works to reduce the amount of covid in the air.
Increasing ventilation is unsurprisingly recommended by the CDC, the EPA, and basically every other relevant group. The EPA has a list of papers here if you're interested in scientific measurements backing this (but can I also say it's just common sense?): https://www.epa.gov/indoor-air-quality-iaq/indoor-air-and-co...
Every organism is alive only in a certain medium. Viruses "come alive" in a host, e.g. a human body, or in solution. Humans are live only in Earth's environment. There is no life without the context of the broader environment that it can live in.
It's pertinent to indoor air quality and interpreting an indoor C02 reading, specifically per its implications of indoor air quality and the ability of virus to survive at that lowered quality.
I live in a place that's generally cold for a large part of the year, so I have all windows shut for most of the time. I've discovered that tracking CO_2 levels is a very good proxy for general air quality, and a good measure of both when to open windows and for how long to keep windows open.
For my apartment, I was surprised that the amount of time I needed to keep the windows open was 5x longer than what I initially assumed (I assumed 5 mins would be enough. Data shows that I need about 25 mins to get CO2 levels down to around 500ppm). I was also surprised to see how much more rapidly CO2 builds up when I have just 2 additional people at home.
[0] https://www.airthings.com/view-plus