Make them mostly async, bringly only the very pointy details that need nutting down sync. If knowledge transfer is needed in a meeting that could be done seperately.
Put it this way do you need to book a 3h meeting with your spouse to decide if to buy a house? Nope all the research and decision criteria were in advance. That final minute of making the decision is a cross check over that work.
I really wish a Apple or another major OEM would integrate CO2 monitor into watches or smartphones. Suddenly, everybody would be aware of the CO2 level in the room, get alerts, etc. and the problem will just solve itself.
There are so many rooms, classrooms, movie theaters and other places with poor ventilation where you just feel dizzy, or fall asleep, not knowing it was just due to lower oxygen levels in your blood. Raising awareness is the only real solution.
I don't think that's true at all. Capnography, the measure of carbon dioxide partial pressure is wholly separate from pulseox:
> Pulse oximeters have some limitations. They can only employ light at two wavelengths. Thus the devices can only distinguish between hemoglobin and oxygenated hemoglobin. When carboxyhemoglobin and methemoglobin are also present, there are two additional wavelengths required for differentiation. In the presence of elevated carboxyhemoglobin levels, pulse oximetry overestimates the true saturation of oxygen as carboxyhemoglobin binds with a higher affinity than oxygen. In the case of carbon monoxide poisoning, the absorbance spectrum of carbon monoxide is very similar to hemoglobin, which results in a falsely high level of oxygen (overestimation of oxygen saturation) ...
> The article references a study where the CO2 proportion going from 0.04% -to 0.25% causes mental problems. In other words, a difference in 0.21% of the air.
I'm finding that pretty difficult to believe, to be quite honest with you.
And before you say "aha, carbon dioxide brain fog!" consider that I'm about a mile from the sea with a 40mph onshore breeze. This air is about as oxygenated as it gets.
The air in your lungs sits around 40,000ppm or 4% carbon dioxide.
In every breath you remove about 25% of the oxygen from the air in your lungs, which is why mouth-to-mouth resuscitation works, at all. Most of the oxygen is still in there.
To be clear, that 25% represents a change in oxygen level from around 21% to around 16%, so the few tenths of a percent change in carbon dioxide just isn't a huge amount.
It makes a lot of sense actually. You get severe symptoms when CO2 makes up only a couple % of the air. And can become fatal at like 5%. There’s not like a hard line where you suddenly die, it’s a gradual thing. It very much makes sense that we’d notice minor symptoms at a few thousand PPM when it only takes like ten thousand to feel it severely.
I got a monitor as we had an old apartment with bad ventilation. When I started feeling it I would check and it was always around 1200ppm and would open a window for a bit. Outside air is around 420ppm, but that's not the problem, enclosed and badly ventilated rooms are if you spend a few hours in there.
I really must learn to quote the full context of a reply. OP said:
> just due to lower oxygen levels in your blood
So my comment is in response to that.
PS. The downvote button isn't a disagree button. (Although how you can disagree with the fact that Apple watches have a blood oxygen sensor I don't know).
I guess the problem is with the price of the sensors. Just look how expensive the Aranet 4 home shown in article is. There are worse devices for less like the IKEA alpstuga. I also don’t know how much electricity they pull.
I got the ikea sensor, I’d say it’s way more accurate than you need for personal use. I wouldn’t use it as a scientific instrument but it’s well good enough to see if the room is ventilated enough.
I was shocked to see just how fast CO2 climbs while in a room, and how just opening the window just a crack was enough to restore the room to baseline co2.
The thing runs on usb 5v so the power consumption is negligible. It also plugs in to home assistant great.
I don't think power use is the issue. I have this cheap CO2 sensor: https://www.domadoo.fr/en/devices/5882-heiman-zigbee-air-qua...
It draws a constant 0.5W. That includes thermometer and humidity sensor, Zigbee transmission, and acting as a Zigbee router, but it gives us an upper bound.
It also measures continuously (picks up someone breathing on it within 10s), which is overkill. A phone could measure CO2 levels once every 10 minutes which would average under 0.01W, so that would work.
However, this assumes the sensor would fit in a smartphone, which is not a given. And these things need air flow. And they also wouldn't work while the phone is in a bag or a pocket.
>A phone could measure CO2 levels once every 10 minutes which would average under 0.01W, so that would work.
Not sure about that, at least NDIR sensors have to be at certain elevated temperature to work and they do some preheating when you turn them on from standby.
So it's not possible to just measure less often as then energy would have to be spent on heating the sensor.
I've got a NDIR CO2 sensor about 6 weeks into a supposed 1 year battery life, still reporting 100% battery. Power use is very low since it only fires up the CO2 sensor every 30 mins.
I'm using a bunch of IKEA's "smart home" stuff, all via Zigbee+HA, works great. Look for the Zigbee icon on the package, and the pairing for Zigbee vs their own home controller might have slightly different pairing sequence on the device, otherwise it just seems to work.
They recently overhauled their lineup and replaced all Zigbee devices by Thread + Matter. Some of the new devices (mostly those who support TouchLink) have a secret pairing mode with which you can use them with Zigbee, but it's only a subset of the new products.
> They recently overhauled their lineup and replaced all Zigbee devices by Thread + Matter.
Uuh, seems not keeping up with social media finally backfired. That sounds horrible! So far IKEA been a great experience when it comes to HA+Zigbee stuff, and I started buying stuff relying on they'd keep just keeping up with that, really sad to hear they've changed course.
The "secret pairing mode" stuff sounds the same as currently/before though, but they only do so for a subset is new and hope they again change their mind.
Yeah, I bought a bunch of INSPELNING smart plugs when they were clearing out the inventory. The new GRILLPLATS switches are more compact though, which is nice.
Thread is significantly better. Zigbee relied on proprietary hubs and apps or hacky work arounds. Matter over thread devices don't need a brand specific hub or app. You can literally control the new ikea products direct from a modern iphone which includes a thread radio, no hub, server or app required.
If you already own the ikea hub, they secretly put thread radio in it which was just sitting unused in preparation for this range.
It's complicated. Matter over Thread is indeed nice in that it you only need generic Thread and Matter servers. It also makes it easier to share credentials between ecosystems. Thread itself is also a pretty nice standard technically.
There are also strong downsides though, one is privacy and future cloud lock-in. Zigbee is fully local. Previous Thread standards added the option for NAT64 so that Thread devices can access the internet and there were some Thread + Matter devices that already require internet access for full functionality (IIRC some Nuki smart locks, but I might misremember). However, Thread 1.4 also adds support for Thread devices to get a globally routable IPv6 address. The Thread 1.4 whitepaper is pretty blunt about what this enables:
Simplified Cloud Integration: Thread devices can now seamlessly connect directly to cloud services, enabling remote control, monitoring, and over-the-air firmware updates.
The fact that Thread and Matter are strongly pushed by Google, Apple, etc. should tell you enough.
Now, a TBR may simply allow you to disable NAT64 or globally routable IPv6 addresses (e.g. Home Assistant's addons), but many consumer implementations don't. E.g. the Apple TV is a Thread Border Router and does not allow disabling NAT64, so Thread devices can access the internet, send analytics, and can be cloud-controlled.
Also, the ecosystem is still pretty immature, as a result of which you can encounter issues, typically resulting in unstable device connectivity. E.g. TREL does often does not work well. Apple has some hacks to fix most of the issues, but it only works well between Apple devices. So it's generally the best to avoid combining multiple TBRs into the same network.
Thanks for this info. I've been patiently waiting for Thread/Matter devices so that I could just use my AppleTV as the TBR and not need any Zigbee gateway. And not need HomeKit-specific devices; just use generic ones.
But I'm certainly not about to let simple IoT devices have any internet access at all. Being unable to block this on the TBR as you suggested would be mandatory for me, and not possible on AppleTV.
Better than what already exists and is deployed? I dunnno, hardware already in use always beat "hardware conceptually better but I don't have it", that's why Zigbee is better, for me. Protocols much like everything in the world, isn't correct/incorrect or universally "better", it's all down to use cases.
Personally, as someone who started to rely on IKEA providing Zigbee devices, Thread is obviously worse, because 100% of the devices I have are already Zigbee and not Thread.
I have HA send me a notification to ventilate my office when the air reaches 1000ppm CO2. The IKEA ALPSTUGA is often off by 300ppm even under 1000ppm. If I'd use it, I'd be getting notifications at 700ppm.
It is a thermal conductivity sensor, which is a very indirect way of measuring CO2 and is very sensitive to environment factors. You only get somewhat good readings in lab conditions.
I would hesitate to say the IKEA is worse. Inside the IKEA is a reputable Sensirion all in one sensor module. It's much cheaper and smaller because the CO2 sensor in it is using different (newer) technology that only released a few years ago from Sensirion.
No, it is crap. Yes, it is Sensirion, but it uses a thermal conductivity sensor, which is a very indirect method of measuring CO2. One part of the sensor emits heat and the other senses it and the idea is that heat transfer changes with different CO2 concentrations. However, a lot of other factors influence this as well, such as ambient temperature/humidity (which is why the sensor incorporates measurements from an SHT sensor), but also gas mixture, etc. You only get good readings at lab conditions. Even below 1000 ppm, I would often see readings that are 300 ppm from more expensive, known-good CO2 meters.
If you want a CO2 meter on the cheap, either wire up an optical NDIR sensor like the SenseAir S88 (22 Euro) up to an esp32, which is possibly the best sensor you can get for the money (slightly cheaper version of the sensor that the AraNet4 uses). Or if you want something standalone with a display, get the SwitchBot Meter Pro CO2 for ~50 Euro, which uses a photoacoustic NDIR, but is still miles better than the sensor in the ALPSTUGA. Can also be hooked up with HA through an ESPHome BLE proxy or with the SwitchBot Hub.
(Upd: the IKEA does have lower accuracy, with ±100 ppm instead of ±30 ppm. From the SEN63C datasheet)
You forget to mention that it is ±100ppm plus ±10% of the ambient ppm, which makes a big difference. At 1000ppm it's ±(100ppm + 0.10*1000) = 200ppm and that's only in an environment with 25C, 50% RH, and 1013 mbar. So, that does not tell you much, given that thermal conductivity is very sensitive to environmental factors.
Worse specs? Sure. Worse value? I don't think so. Worse accuracy? Wellll, maybe also not.
A price of 30 EUR makes this sensor really easy to pick up. For the same price as one Aranet (~180 EUR) the typical household can place a sensor in every room of the house. Which provides far more accurate readings for the whole house than just one high-end sensor in one room.
I have one IKEA Apstuga on my desk, sitting right next to a good CO2 monitor.
Since Apstuga uses worse approach (heat) rather than light as the good sensors, it diviates around +/- 100 ppm. For example the correct CO2 is 610 ppm and IKEA's sensor shows 552 ppm with is reasonably close. So the trend will be correct and the values will not be.
But when it goes over the safe limit it should be enough to decide to ventilate.
Ruuvi Air[1] seems to be close to the middle in both price and CO2 measurement accuracy between aranet4 and the IKEA device. I don't have personal experience with Ruuvi Air specifically, but have been using their cheaper Ruuvi Tags (that don't measure CO2) for temperature, humidity and air pressure measurement at home and office.
You'd have to raise awareness on every single person in the room and them sustain pressure to the organization in order to have proper CO2 levels in the room/organization.
And then you have to align every other person on every other organization to do this as well and hope for the best.
Or, you can do the right thing and have the state introduce regulations
I can just imagine the horrors and skin crawls that your last sentence has evoked in some people's minds. Not the state!!
But seriously, so much care needs to be taken here. OK, well "care" at least. Employers certainly would benefit from scrubbing CO2 from the air, in terms of productivity. I'm willing to bet that with central air it would be quite easy, and even with heat and AC off, lots of places still circulate the air regardless.
So the central place to scrub is already there.
But then you have other issues. Such as, will your body adapt to 8 hrs of reduced CO2, and then you become torpid and barely awake when not at work. Such a horrid thought, that is to me. And what if employers learn that the tiniest boost of O2 helps too! Now your body becomes accustomed to that, and what are the long term effects there?
I can personally envision myself being concerned. I guess the legislation could be crafted to "the same CO2 levels found just outside of downtown city core" or some such blather. Maybe even same for O2. So that you're at least pegged to something normal for the area.
Maybe that's where the state could come into play. A simple, highly accurate monitoring station which has an API to be polled.
Come to think of it, CO2 and O2 rates fluctuate during the 24 hour cycle. Trees need O2 to live, but only produce O2 during the day. And so differing amounts of light might mean up and downs in these numbers. It may be another circadian rhythm. Getting it the same as in a nearby forest, might be the healthiest thing of all.
In practice, one would use energy recovery ventilation to exchange air with outside rather than a CO2 scrubber (not clear if you actually meant a scrubber).
I have been in some office buildings in United States which had CO2 monitors in each meeting room, and the ventilation would engage to control CO2 below a set level. We would entertain ourselves by exhausting our lungs onto the sensors to trigger the ventilation system.
I should have said it more clearly, I just thought HN would take this stance regardless. If you tell an employer to ensure CO2 levels, and it shows an improvement in productivity, employers may think "Hmm. Let's improve this further!" and add O2 as well.
In terms of outside air, a lot of US cities I think would not benefit from that, all that much. Especially during certain parts of the day, with a lot of smog.
But regardless, all that entered my mind was "Once employers are required to add any form of scrubbing, and perhaps O2 injection, they'll over do it for optimal employee output." Regardless of whether it's helpful once the employee leaves the workplace.
I'm not against this, I'm just actually saying the regulation should be locally defined.
Controlling indoor CO2 is important, but it's a proxy metric for the escalation in indoor bioeffluent VOCs which are a tiring subset of total VOCs. This is why scrubbing indoor CO2 will by itself never produce the pro-cognitive result you want. See https://www.aivc.org/resource/effects-carbon-dioxide-and-wit...
Scrubbing indoor CO2 is sensible only when you want to go below the outdoor CO2 level, not at levels above it.
I don’t think that’s right. If people have an easy way to measure the levels, and they can see something on their phone like ‘you spent 8 hours today above 2000ppm CO2’ then the room will care a lot more than it did before, and people will be able to quickly see whether they have improved things. At my employer, I think it took us around 1000 employees until we randomly hired someone who happened to care a lot about CO2 levels and I think they managed to cause a decent increase in the amount that the company cared / thought about levels (this was around the end of Covid though so part of this may have been due to using CO2 levels as an indication of insufficient ventilation/air filtration).
Depending on the state, newer buildings do have regulations on air ventilation and quality.
The rooms being discussed here are mostly ones which would have been built before this was taken more seriously. Classrooms, older office buildings, etc.
NYC is full of buildings which would never pass any code today but are still happily occupied. It’s a trade off, I think.
It doesn't work like that. I've been made aware thanks to this post, and tomorrow I'll be placing CO2 sensors in every meeting room in the company I work at, and mandating an open-windows or air-circulating policy above 800ppm.
You don't need to make everybody aware, you just need to make the right people aware.
As for the State... Mine mandates that nobody can use the laptop's keyboard, they must use an external keyboard so the laptops' screens can be risen to eye level.
We have the external keyboards and the risers, and nobody uses them.
The State usually finds the worst and most wasteful solution available. Only fools trust the State to solve their problems.
And I believe the accuracy is also not great on these cheap ones. The product in the OP's photo costs $200 where I live! And ISTR finding the sensor itself contributes a lot to this cost.
IIUC they also need fans. The one I have in my home has one that's actually integrated into the sensor unit.
I think the issue is that the common tech requires sensors in an air-chamber. E.g. NDIR works by firing IR at a frequency that is absorbed by CO2. A sensor on the other side either measures the amount of IR light that got through (optical NDIR) or pressure/sound waves (photoacoustic NDIR). I guess that it's hard to use any existing sensors, because they are relatively large and probably water could easily get into the chamber.
Would be extremely cool if Apple, Samsung, and others can crack this, though I think they'd have done it already if it was easy.
Oxygen sensors used in car catalyst systems use a different effect based on electrochemistry. I see no reason that couldn't be minuaritized to grain-of-sand size.
The question is if oxygen levels are as good an indicator as CO2 levels... I suspect not.
there is some ambiguity here. submariners are exposed to really high co2 levels and are doing fine. it's possible that co2 is just a proxy for bad air, and that you can acclimate to purely high co2 pretty well.
i have felt bad in high co2 environments before but i have never been in a controlled high co2 environment.
I'm not implying permanent effects. The studies involved show a marginal reduction in cognitive reasoning on standardized tests.
Which is the point: if you're in a room trying to do deep work, that's likely a problem. I suspect submarines are all over the place here: you might be exposed to higher levels routinely but you also have regular access to chemical scrubbers and decent ventilation. I'd be fascinated to know what levels are tracked as normal.
apparently those scrubbers are less efficient the lower the co2 is (also need to move much more air which ruins stealth). iirc submarines are routinely exposed to multiple thousands.
> I think we use them as a proxy for o2 levels (same as our bodies do).
Probably. ISTR that depriving a body of oxygen results in a different response than overloading the body on CO2. It's why if you completely displace all air in the room with CO2, people choke, panic, etc, but if you use Nitrogen, people just keel over dead without realising it.
The evolved response to CO2 is part of the human body’s ability to filter and remove CO2 via the respiratory system. AFAIK we don’t have similar capacity for Nitrogen because it’s not a primary waste product of that system.
Dissolving CO2 in water creates some carbonic acid (H2CO3) that will decompose back to water and CO2 when the CO2 concentration drops. Blood has a fair bit of water, and carbonic acid is much easier to detect than oxygen or nitrogen gas
We evolved to detect CO2 because that's by far the easiest thing to detect that's still a reasonable proxy for the performance of our respiratory system
I'm pretty sure that in a room where we replaced nitrogen with co2, we would be dead even if O2 concentrations were the same. Something about partial pressure. I notice AI explanations agree with me (not going to copy and paste them).
You are right about the pH implications, but respiratory acidosis leads to hyperventilation, not hypoventilation. CO2 will kill you regardless of oxygen supply.
My medical student flatmates were talking a lot about acidosis and alcalosis :)
It was the first time that I heard about them. These basically never happen if your body and environment are halfway decent, but they are important in exceptional situations.
Electrochemical pile style oxygen sensors continuously deplete themselves whether actively measured or not. Common smart home oxygen piles have a fixed lifetime of a few years, and they're quite sizable (probably about as much volume as a whole smartwatch). Putting the same chemistry in an even smaller package would likely result in lifetime measured in hours
I assume this is because of diffusion of materials at elevated temperature. The sensor would, I think, require a lower temperature than an electrolyzer, since the current would be much lower. But it would be best if lower temperature solid oxide electrolytes could be discovered.
The ones in cars need to be heated up quite a bit in order to work, and you still need reference air. Otherwise, I'm pretty sure that CO2 isn't a problem but rather an indication of a lack of oxygen in the first place, so it technically could work... just not if you're measuring the environment itself.
This is in theory not a problem: getting an oxygen sensor to 700 degrees if it's a tiny spec on a chip is not necessarily hard or would even require a lot of power.
But...oxygen concentration is essentially indepedent of CO2. We measure CO2 at part per million levels, whereas O2 is 20% of the air.
(In that context CO2 is surprisingly toxic given that 1000 ppm can impair mental acuity).
The goal of a gasoline engine's sensor is to accurately and precisely measure the point where O2 concentration reaches zero, so ambient air levels are not quite as relevant.
Based on numbers, O2 concentration is probably not a good indicator.
Clean air contains about 20.9% O2 and 0.04% CO2. At 2000 ppm CO2, which according to the author is bad enough to impair judgement, that's 0.2% CO2, it that CO2 is the result of respiration, it means that about 0.2% O2 was consumed, so that's a drop from 20.9% to 20.7%, a very small difference. 20.7% is not low enough to have a significant effect, the CO2 itself is the problem, not the drop in O2. And using O2 concentration as a proxy for CO2 doesn't look reliable to me: the difference is small and other things, like humidity can affect O2 concentration.
As for the sensor, O2 sensor in cars compare the O2 concentration between the outside air and exhaust gases, it needs outside air as a reference, but what you are measuring is the outside air itself, you don't have that reference.
CO2 concentration doesn't start at zero, and by coincidence, if CO2 production is 80% of oxygen consumption, consuming 0.2% oxygen results in 0.16% CO2, add it to the base 0.04% and you get 0.2%.
It looks that some O2 sensors that don't require a reference have been used (titania sensors) but even though they have some advantages, they are less precise and mostly obsolete.
I had a project miniaturizing nasa tech for detecting hypoxia with o2 and CO2 sensors. It used a phosphorescent dye that changed a delay flash (ie you blinked a light, the dye would absorbed and blink back after a delay) based on temp and o2.
CO2 was measured with infrared but water also absorbed it, so you need to heat things up enough to not have water. It can be small, but not watch small.
> CO2 was measured with infrared but water also absorbed it, so you need to heat things up enough to not have water. It can be small, but not watch small.
Can't you just measure CO2 "naively", then also measure rH, and use the value to grab a research-calibrated LUT to pass the CO2 value through?
CO2 and all other air quality indexers have to be very carefully calibrated regularly. It's not some slop you can just throw into a consoomer cheap iot device.
Article author completely ignores this for the obvious reasons.
For the purposes of indoor ventilation monitoring you can calibrate by occasionally exposing the sensor to fresh air. Either taking it outside or just the room not having people in it. The sensor will treat the lowest reading it gets as 400ppm since this is what outdoor air is.
A sensor mounted in the office will get calibrated every night when the office is empty.
You don't need to calibrate a good device at all for that purpose. It already will maintain a reading within 10% of the real value. If it's not doing that, it's a bad device. It's very possible your calibration process will actually miscalibrate it and increase the error.
Also, already the outdoor CO2 level is 430, not 400.
If you want to make measuring CO2 your obsessive compulsion then sure, buy a lab grade instrument. If you want to get a practical reading of the air quality that is more than good enough, affordable, and looks nice on your bedside, the ikea one is a great option.
Not really. For ventilation purposes, a good sensor remain within 10% variation for nearly ten years. We are not running a controlled science experiment here.
> There are so many rooms, classrooms, movie theaters and other places with poor ventilation where you just feel dizzy, or fall asleep, not knowing it was just due to lower oxygen levels in your blood. Raising awareness is the only real solution.
Not wrong, but it is perhaps worth noting that there are already standards for proper ventilation. Generally you're looking at 5–10 cfm/person (2.5-5 L/s), depending on the facility and purpose of the room; see Table 6.2.2.1 in ASHRAE Standard 62.1 for the US:
Maybe set up a monitor, but if the room/facility has recently been renovated and meets modern (>2013) building codes, this 'should' have already been taken into account.
I think modern domestic houses its the opposite. At least in Netherlands isolation is such a strong focus, due to climate change I think, that modern appartments have terrible ventilation
A friend of mine recently moved to a modern apartment, built only a few years ago to a very high isolation standard (Germany). I stayed over night and slept on his couch, the air got really really dry and stuffy. It was really uncomfortable.
Stayed at a beautiful new house in Finland, with five people instead of the usual two, the CO2 detector intermittently went off while we were sleeping. Which the hosts assured us was a faulty detector. They also spoke to how extremely energy efficient the house was, to us it seemed like there wasn't enough ventilation, to improve the insulation. Against their wishes, I slept with all windows fully cracked, which was only ~2 inches due to the "efficient" design.
Poor ventilation is mostly an issue in homes built or renovated in the 1970s, when the oil crisis led to ill-considered efforts to save energy. New homes typically achieve energy efficiency by using heat pumps in the ventilation system.
How modern? We built or house in Belgium in 2016, and it was completely sealed, very well insulated, but the air quality was good because we had mechanical ventilation. Clean air blown in, stale air extracted which then went through a heat exchanger.
The only issue this house had was it overheated. We had glass facing south. Even in winter it instantly became too hot.
Energy recovery ventilation is the answer to this.
HRVs only deal with temperature, but then you have humidity that is non-controlled: moisture coming in during the summer, and getting vented out in the winter (too-dry air coming in).
> I think modern domestic houses its the opposite. At least in Netherlands insulation is such a strong focus, due to climate change I think, that modern appartments have terrible ventilation
The link I pointed to is all about ventilation, so just because people ignored important component of building science, and focused on one aspect, does not invalidate it.
And while climate change is important and using efficiency to deal with it is useful, the thermal control layer is actually the least important of the four:
Building codes that address this are wonderful, however:
- Plenty of people live or work in older buildings, where are not up to standard. For example: my office probably violates the air quality sensibilities of the Victorian era, which is when it was originally built.
- Equipment breaks down, isn't operated properly, or wasn't installed correctly. Having monitors that measure air quality is an extra check. While you may not be able to get direct action upon a consumer sensor, it can help you push for action.
I've been in buildings of varying quality over the years. I've seen how it takes time to get people in to do air quality testing. Heck, I saw the government claim that the air quality was acceptable in schools during the pandemic because the schools had passive ventilation systems. That meant they could open windows. (To be fair, the air quality in most of those buildings was probably fine since that was how the buildings were designed. That said, such standards make it easy for some buildings to slip through the cracks.)
And let's not forget unscrupulous building owners/renters who will not employ the at least 10% fresh air intake rule on their HVAC system. This fresh air is outside air temperature, so their system has to change it's temp according to the thermostat setting, which costs money.
Fresh air doesn't have to be outside temperatures as you can heat exchange most of the energy from exhaust to intake without putting in additional power.
This is correct, but there's still a lot of opportunity to do better.
I've been involved with the build out of several office spaces in new and old buildings. We always took this sort of thing seriously and measured each room independently for a week (many at a time) ensuring we accounted for periods of high occupancy.
This let us tune the HVAC systems to operate more efficiently, ensuring comfortable temperatures and air circulation. Every time I've seen this done there were structural deficiencies that required remediation, some times it meant adjusting duct work.
Most modern office buildings are designed to be a platform for constructing spaces, as spaces usually evolve and change between leases and tenants. They're designed to accommodate this sort of thing.
However I've found that no build out nails this the first time. It's very hard! Often times things look fine but once you get people in the space things change drastically. It requires time and effort to address.
Several of my offices had such good air that I'd prefer being there over pretty much anywhere else -- even outside on poor AQI days.
I've also found that a lot of offices don't do any of this and their air quality is noticeably poor. And lastly I've found that the oldest buildings, including schools -- and I'm talking really old -- have very good air because they are so incredibly leaky. They're usually harder to cool and heat, though.
Whenever I travel, I bring a CO2 meter with me. It’s amazing how often the air is bad. Often in unexpected places. My meter hit 3100 in an uber once. I didn’t even notice until I got to my hotel room and looked at the data log. It was a fresh, hot day outside. The uber had windows closed and AC on. I bet he had no idea - but he was driving with significant cognitive impairment. Takeoff and landing in planes are always the worst. If you get sleepy as the plane is taking off, it’s not you. The plane’s ventilation doesn’t work properly when the plane is stationary. So before a plane is in the air, they often hit 2500.
He’s not driving with significant cognitive impairment. Submarines and the ISS routinely operate at 5000 PPM. 60 years of studies and almost a century of operating submarines has shown no impairment at 5000 PPM.
Then all of the sudden Satish 2012 comes along and shows serious cognitive impairment at 1000 PPM. The only studies that have replicated this involved Satish. Studies without Satish as a coauthor fail to replicate their findings.
If you think about it for a second, the levels of impairment Satish shows don’t make sense at all. You’d expect to see differences on SAT scores of hundreds of points between test centers with good ventilation and bad. You’d expect to see massive differences between regions where AC is more or less common. Or even between seasons.
Is it a tually lower oxygen in the blood that's the problem, or higher co2? I'm not sure if having high co2 automatically implies lower oxygen, I have no idea at all but feels like it may not necessarily be strictly. Linked. Also, are the cognitive issues of low oxygen the same as high co2 or do they produce different effects?
> I really wish a Apple or another major OEM would integrate CO2 monitor into watches or smartphones
CO2 levels are locally elevated in the area where you exhale. Someone sitting at a desk with their hands on a keyboard exhaling through their nose would be producing a directed stream of elevated CO2 straight at the sensor on their wrist. Same thing if someone puts their phone on their desk.
Even with the IKEA and other cheap sensors that are becoming popular, there is a learning curve where users discover that putting it on their desk right in front of where they’re breathing produces higher numbers than having it even 5 feet away.
The false positives from having a CO2 sensor that close to everyone’s face would be causing unnecessary alarm all over.
> There are so many rooms, classrooms, movie theaters and other places with poor ventilation where you just feel dizzy, or fall asleep, not knowing it was just due to lower oxygen levels in your blood. Raising awareness is the only real solution.
If someone is falling asleep in this many different places I would suspect undiagnosed sleep apnea or another condition first and foremost. Spaces like movie theaters have very high volumes of air due to their size and commercial building HVAC has much higher standards for air circulation than even your home. If someone was falling asleep in so many different places then the most likely common theme is that person and it should be checked out!
This is another reason why putting CO2 sensors on everyone’s wrists would be a mistake: It would start getting blamed for every vague condition people experience. This has already happened with wrist-worn heart rate monitors. My friends in the medical field see people all the time who come in with vague complaints and they’ve self diagnosed as being related to their heart because they can see their heart rate now.
You also have the wrong idea about what elevated CO2 does. It doesn’t reduce the oxygen levels in your blood. It makes it more difficult for your body to expel CO2, which can produce subtle changes in many processes.
CO2 does not stream out when you exhale like a fluid. It’s a gas. It dissipates quite immediately and behaves as all gases do - it expands to fill its container via something like Brownian Motion.
The CO2 content is a single chemical species within a mixed gas. Any air currents will cause mixing. Otherwise it undergoes diffusion which is actually a fairly slow process, although much faster in gases than in liquids.
Wouldn’t it still be useful because you could look at changes in the measurement? E.g. if I can’t draw any conclusions when my phone says 800 at the start of a meeting because it might be where I’m breathing, but an hour later in the same place it says 2500 couldn’t I conclude we need to take a break and let the room air out?
If you had the data, what would you do to change it? Would you recommend everyone go outside? You can do that without the data.
Would you wear your own oxygenated supply of air? You can do that without the data.
Would you make recommendations that the office should improve air quality? You can do that without personalized real-time data.
I'm not against data in general, but the idea that if only we had data we would make changes in our lifestyle is not valid. We see it all around us.
We had bathroom scales for over a century, but the data or insights didn't put a dent in the obesity epidemic.
You're right about "the problem will solve itself", but it isn't the data that will help to solve the problem, it's creating a simple and obvious solution.
A friend has a start-up in the commercial air quality space which solves for this problem (in some ways). But the benefit isn't the air quality, it's the cost of maintaining the healthy levels required in commercial buildings. Air quality is the secondary benefit of reduced electricity demand in air circulation.
Don't forget too, if the CO2 is 1000 ppm, then half of the air in each breath you inhale was recently exhaled by someone else. Yes, airborne viruses are still spreading. I still wear an N95 mask whenever I'm in an indoor space with other people outside of home.
IKEA now has a remarkably cheap ($35) air quality monitor that measures CO2 as well as PM:
I don't have one yet but plan to pick one up soon. A CO2 sensor alone from Adafruit is $50+, though that one is more precise. I bought it a while ago and it's still sitting in my todo bin.
The building science community has not buy and large came to the agreement that the CO2 itself is the cause of the cognitive decline. It could be the Canary in the coal mine telling us there is an accumulation of compounds causing the decline.
Why that matters? You need good ventilation regardless, but instead of just thinking of CO2, try to minimize compounds in your air by selecting things for the room that smell less and off-gas less.
Though that study included a 45 minute acclimation period. Appropriate for submarines, but I wonder what the results would be in the first 1 / 5 / 10 minutes.
I mean that can't be right, as the body's breathing response is triggered by that amount of CO2 buildup. It's not about what's in the air. It's about what the body can take up. Maybe submariners are self-selected to be more physically fit, e.g. larger heart, lung capacity etc. to compensate.
One key difference is that submariners are rigorously trained to operate effectively in less-than-optimal environmental conditions, whereas Bob from accounting probably is not.
I don't think you can cleanly compare this: In the study, they added CO2 to the room, while keeping O2 at normoxic levels throughout the experiment. In your meeting room, O2 levels will be dropping in lock-step with the CO2-levels rising. It may be the lack of oxygen that leads to drowsiness, not the additional CO2. But it's the CO2 levels that you can measure as a good proxy of overall air quality.
I don't think this is correct. The concentration of CO2 in air is about 0.04%, whereas the concentration of oxygen is 20%, so the partial pressure of oxygen is about 500x higher. This means that if, for example, 10% of the oxygen in a room spontaneously disappeared, it would be replaced about sqrt(500) = 22x faster through leaks in the room than a 10% spontaneous CO2 increase would dissipate. (This ignores a small effect due to the different density of the two gases).
So in practice the oxygen level can never drift meaningfully far from the atmospheric pressure, whereas carbon dioxide easily can because the pressures involved are so low.
The Satish 2012 study that seems to have started this trend was a small cohort of 22 people split in 6 smaller groups where they also just injected pure CO2 in a small room. There have been several attempts to reproduce, which sometimes found no clear effect, or a significantly smaller effect.
This original study has been used to market these CO2 monitors for years, but the evidence is quite thin and doesn't support a strong effect. It seems likely that there is a small effect, and it has been wildly exaggerated thanks to a small study with N=22.
Can it not just be that what happens in stuffy meeting rooms is boring? Opening the windows changes the temperature, the noise levels, perhaps the light levels ≈ adds some novelty, which makes you feel a bit more awake.
I think this is (in turn) wrong. Yes: having 500x the amount of O2 as CO2 means that a 10% drop in O2 will trigger 500x as many molecules diffusing in per second as the same drop in CO2. But, each molecule of CO2 will change the relative percentage 500x as much as a molecule of O2, so isn't it a wash?
... which is entirely unsurprising given that exhaled air is about 50.000 ppm CO2 and can vary by several 10.000s depending on depth and rate of breathing. I actually consider the recent wave of findings that CO2 levels as low as 500-1000 ppm measurably affect cognitive performance and well-being to be a great example of how you can prove literally anything with statistics and a sufficiently small sample size.
A major confounding factor is everything else in the air. Humans produce lots of different gases, and CO2 is usually a proxy for the overall concentration of our effluent gases. But in a submarine, or in some buildings, there are gas filters (usually carbon, possibly with various modifications) that can remove or destroy some of these gases but have no effect on CO2. So the air in a submarine at 15000ppm CO2 could be very different from the air in a an unventilated room that reaches 15000ppm CO2.
The first person to deal with this may have been Cornelis Drebbel in 1610 when he deployed the first submarine. With 4 oarsmen submerged in a leaky wooden sub, they’d have too much co2 and too little oxygen. Somehow they were able to stay for hours at a time.
Robert Boyle describes Drebbel’s use of a “chymical liquor” to refresh the air.
“Paracelſus, indeed, tells us, that "as the ſtomach concocts the aliment, "and makes part of it uſeful to the body, rejecting the other; ſo the "lungs conſume part of the air, and reject the reſt." Whence, according to him, we may ſuppoſe a little vital quinteſſence in the air, which ſerves to refresh and reſtore our vital ſpirits; for which purpoſe, the groſſer, and far greater part of the air, being unſerviceable, it is not ſtrange that an animal ſhould inceſſantly require fresh air. This opinion, indeed, is not abſurd; but it requires to be explain'd and prov'd: beſides, ſome objections may be made to it, from what has been already argued againſt the transmutation of air, into vital ſpirits. Nor is it probable, that the bare want of the generation of the uſual quantity of vital ſpirits, for leſs than one minute, ſhould be able to kill a lively animal, without the help of any external violence. And, upon this ſuppoſition, Cornelius Drebell, is affirm'd, by many credible perſons, to have contrived a veſſel to be row'd under water: for Drebell conceiv'd, that it is not the whole body of the air, but a certain ſpirituous part of it, that fits it for reſpiration; which being ſpent, the remaining groſſer body of the air, is unable to cheriſh the vital flame reſiding in the heart. So that, beſides the mechanical contrivance of his boat, he had a chymical liquor, which, by unſtopping the veſſel wherein it was contain'd, the fumes of it would ſpeedily reſtore to the air, foul'd by reſpiration, ſuch a proportion of vital parts, as would make it again fit for that office; and having made it my buſineſs to learn this ſtrange liquor, his relations conſtantly affirm'd, that Drebell would never diſcloſe it, but to one perſon, who himſelf told me what it was.“
I’m not saying this isn’t a legitimate concern but this really seems to have exploded amongst the tech community as the next obsession.
I see this pop up on X every few weeks. Is the concern about this really based on actual science? Is there empirical data proving people are less productive or are damaging themselves as a result of heightened CO2 levels? And I don’t mean observational epidemiology studies.
It's peak HN meme material because 1) it affects your intelligence which everyone here values highly 2) you can measure it, it's a number 3) requires tech to measure it
So perfect for HN, you can obsess over tech and how to measure it endlessly and overhype the significance to trick yourself into thinking you're doing something useful.
You get to have your cake and eat it, no wonder everyone loves this topic.
(Also if you're a doomer type you can link this in with rising atmospheric co2 levels for extra points)
I’ve lived in Australia and France and I’ve always attributed the taller size of Australian was due to the excellent state of their ventilation in buildings. Vents (and rooms themselves) are systematically bigger than in France, and if you live in a healthy environment, with meat, lots out outdoors during teen age, and correctly ventilated classrooms during their 20 best years, it makes no secret to be that they grew bigger.
Meanwhile in France we heat classrooms by stacking 35 kids in a confined space. It saves on heating, plus condensation that makes windows opaque helps pupils concentrate on the blackboard, as teachers said during my childhood.
France is indeed ridiculously bad at ventilation (not to mention air conditioning). Restaurants, offices, even gyms - most have bad to non-existing ventilation. Coming from the States this is just insanity.
> I’ve lived in Australia and France and I’ve always attributed the taller size of Australians to the excellent state of their ventilation in buildings. Vents (and rooms themselves) are systematically bigger than in France
The average male height in France is 178.60 cm, while in Australia it is 178.77 cm:
IMO it's something where an intervention is often cheap enough that it's worth it even without great evidence.
But also bear in mind that regardless of "are we operating at max effectiveness", OSHA sets a legal limit of 5000ppm in a workplace, and that's about _safety_.
This article is talking about keeping levels below 1000 which is a very high standard IMO. But if you are in a poorly ventilated home office you could easily hit 3000. At that point you are closer to "illegal in the US" than "earth's atmosphere".
So yeah even if you are unconvinced about micro-optimising your CO2 levels there's a very long established argument in favour of at least paying _some_ attention to it.
It's not even that hard to optimise at home. I've found simply leaving the door open to the rest of the house causes the room CO2 to not elevate much over baseline outdoor readings. Or just opening a window just a crack will rapidly remove all excess co2.
The real problem is offices and meeting rooms where you have 10 people in a small box for hours and windows that don't open.
That's interesting coz I found the opposite, at my place to keep the level below 1k I usually have to open a window in the room I'm in, or use a fan.
I live on a noisy street so I don't usually want to do that, if I open a window at the back and keep internal doors open it will stay reasonable but significantly elevated.
So yeah I think the lesson here is you probably need to buy a sensor, different homes are gonna differ.
My home is quite small (probably 80m²) and has literally zero ventilation built in (even in the bathroom!). I live in Switzerland where it's traditional to actively ventilate your home twice a day. But that doesn't do anything for CO2. Also it's such a fucking waste of time lol. Looking forward to moving into a modern building.
I think it’s just quite windy where I am combined with a not particularly airtight building so opening the window just a crack results in a lot of air blowing in
Yeah I was thinking airtightness might be the difference. My flat seems to be bizarrely hermetic (when you turn on the kitchen extractor fan, it struggles if you don't have a window open somewhere).
So maybe a few leaky cracks are enough that when you open a window you get a bit of a through-draft.
That is also my impression. CO2 build up provides a neat opportunity to carry around sensors, track something, display graphs and formulate quantifiable sets of rules. And also is a (more or less) interesting topic to discuss with others. Seems highly appealing to a large part of the crowd here. Personally, I only observed that some people are obsessed about having always one or more windows open but I never personally experienced any non-obvious problems with CO2 buildup. At some point the air is just smellably getting thick and then you just air out. Wouldn't need sensors for that.
Nope. Opening windows is very often disallowed - whether socially, or you'd need a hammer, or the space doesn't have windows. Or opening windows would have other downsides - letting in rain, or too-hot/too-cold air, or pollution, or ...
Can't let those stupid workers open a window and ruin the efficacy of the precisely engineered hvac system that lets the building hit LEED Platinum or whatever
Yeah. But even when you can, how many bosses might forbid it - because there's already too many arguments over the thermostats, or it's kinda noisy outside, or HR warned 'em of lawsuits for doing that when the air pollution numbers are elevated, or whatever?
I've been designing my own ERV system for the house and have been weighing all the options, so I had this list in my head. Nothing dramatic, just the reality. We have allergies and like sleeping in a cooler bedroom.
Anecdotal, but I'm convinced it screws up sleep quality. I'd just accepted for the longest time that waking up groggy with a slight headache and tired was the norm until I put a CO2 monitor in my room. With the door closed, it climbed up to 1500ppm in under an hour.
I'm certain many people are sleeping in similar conditions without realising and ventilating their rooms properly or leaving the door open.
> Anecdotal, but I'm convinced it screws up sleep quality.
It absolutely does.
>I'd just accepted for the longest time that waking up groggy with a slight headache and tired was the norm until I put a CO2 monitor in my room. With the door closed, it climbed up to 1500ppm in under an hour.
Same experience here. Opening windows just a bit totally changed my sleep quality.
We assume sometimes that everybody experiences this in the same way, but a lot of people might be super-sensitive to it, and others completely immune. It is quite possible that the ones obsessing about it are the sensitive ones, because they feel it much more.
I agree it seems like a concern fad. I talked about it once with my brilliant MIT-educated 20 year Navy submariner brother-in-law and he didn't commit one way or the other but did say submarines have CO2 in the low thousands.
You'd think (hope) if there was a big effect here on performance, the relatively cheap/easy solution of maintaining lower CO2 would be standard. I know people think of the military as dumb grunts who you don't want to think, but he was one of the four department chiefs onboard (Weapons, Nav, I forget the others) and they have pretty substantial responsibility to make decisions on their own.
Any affect from CO2 specifically seems weak. Clean air in broadly good though, and high CO2 is a good proxy for stale air. So I’m always supportive of people caring and paying attention to their air.
Along the way they’ll either learn about or accidentally mitigate other ills like radon, nitrous oxide from stoves, diesel particulate’s impact on test scores, etc.
I feel like it exploded after the cheap integrated sensors came on market that were easy to DIY with. It's nerd catnip, it makes you feel like you're discovering some hidden truth and makes it very tempting to blame the readings for all sorts of things. I don't even know how to trust the calibration on these things.
It kind of reminds me of the old joke where a drunk is looking for his keys under a street lamp even though he dropped them in a dark corner of the parking lot.
The level at which it is a concern might be skewed, but if you’ve ever sat in a room with “thick” air, trying to concentrate you know it is a real thing and just opening a window and a door for a few minutes to create a draft helps tremendously.
CO2 is just a tip as office or home is toxic environment anyway. Plastic (e.g. carpets), formaldehyde in furniture, air fresheners… add home office and cooking at home (-> small carcinogenic particles)…
If you start reading How not to die by Michael Greger, you find out that dust, soda and sitting - not CO2 - are real killers…
It's similar to how people think sharks and airplanes are the biggest killers - when in reality it is coconuts, mosquitoes, and motorcycles.
Air purifier is good for PM2.5 and other microscopic pollutants but it doesn’t do that much for dust unless it’s particularly light dust and very close to the purifier.
Dust is much more likely to just settle on the ground and be kicked back up than it is to move all the way to the purifier to get stuck in the filter.
I have an air purifier with built in particulate sensor. It doesn't provide numbers, but has a multi-color LED indicator to report PM2.5 level as good/mediocre/bad/terrible. Running a vacuum cleaner that supposedly has a good filter consistently increases the reported PM2.5 level from the first band to the second. The air purifier (or faster/cheaper depending on the weather, just open some windows) can bring it back down again.
Air filters, decluttering, regular deep cleaning, replacing dust-friendly surfaces and furniture (such as carpet, drapes, and upholstered sofas) with things like wood, vinyl, or leather.
HEPA-filter air purifier and a robot vacuum that is scheduled to run while your are not in the apartment (to reduce baseline dust) are probably the most simple/cost-effective measures.
My previous employer had dogs shit on carpets, without proper desinfection! Just smearing it into carpet, waiting for it to dry out, so it can go airborne!
> Then, somewhere in the second hour, the room quietly gets worse at making them.
Maybe it's not just the air but also the multi-hour meetings that drive people to a sense of "oh god let this finally end now", which leads do decisions that fall short.
This reads to me as AI generated. Apparently it's still good enough to the general audience to be the #1 post on HN right now though. Which is honestly a troubling signal for the state of the world...
Nice! Have you considered doing a Show HN or Tell HN for that?
That's valuable in at least three different ways: public education, showing that most of the articles are still human-written which can be easy to forget about sometimes, and as an easy way to cross-validate my intuition when flagging something as AI-generated without having to manually run Pangram.
I despair a little bit about how many HN voters either seem to want to read slop or don't understand when they're reading it. This post is obviously AI generated from the first paragraph on, and still has 480 votes.
Oh this is absolutely so relevant and I wonder if there are any high quality studies that have analyzed driving performance against CO2 buildup in cars. Cars often ship with circulate air feature in the aircon, and people use it aggressively, nonchalantly at least where I live, having no idea about the dangers of possible hypoxia and sleepiness that might be inducing in them while driving. It is absolutely critical in my opinion for cars to have CO2 monitors. We put so many sensors in cars these days that this seems to be a really cheap and fairly high value of life addition that could possibly prevent accidents on roads. I keep a portable CO2 sensor in my car at all times, because sometimes circulation is not something I can avoid when stuck in traffic or when passing by a drain.
Got a firsthand experience with this. I was dropping off my girlfriend and we stopped to talk in the car, with all the windows up. Over the course of the conversation we got more and more agitated at each other until I had a thought and pulled my Aranet out from my backpack. It was >3000ppm CO2. We opened windows and within 2 minutes all the agitation went away.
To be fair, that might not just have been the CO2 dropping, but also the pattern interrupt + giving you both an easy and face-saving way out of that situation.
I'm not sure this is a helpful comment. This is a common story with many medications, where someone notices their feelings are off and suddenly remembers that there is a probable root cause. It's why medications list side effects.
Yeah, I measured over 5000ppm in a taxi with two passengers. Showed the driver how to enable air intake (he didn’t know about the feature) and tried to explain this is deadly. Pretty sure this is commonplace globally.
Generally it’s a miracle to me so many people survive traffic on public roads, statistically.
Naturally I often wonder if many people know what Hermetically sealed is all about to begin with.
I do a bit of that in the lab when I seal flammable reference materials inside glass ampules using a torch. But it's not the sealing that counts, it's the technique ;)
If you check Wikipedia, you may notice that the terminology is older than the internet in every way.
Specifically they do not show awareness that it really means "sealed in such a way that it can't be figured out. As if by God. Not just any God but the ancient Roman God Mercury, otherwise known as Hermes when worshipped by the ancient Greeks."
Now I can only assume you have never been in a new 1960's WV beetle when all windows and the manual vents were shut (they didn't have A/C) when somebody slammed the door. You eardrums would remember it if so.
Your comment actually has me convinced that this isn't an issue. I've been a recirculation dude for my entire life, I literally don't drive any other way.
In the 1970's when factory A/C started to get widespread adoption in other than very expensive cars, it was common for more than one US automaker to almost standardize on a dashboard system of levers or knobs.
At the extreme was "MAX" which most people didn't realize was "recirculate" unless they read the owner's manual in those cases where it was well documented. The next notch over was "NORM" which as the name implied was intended to be the "normal" setting except under more challenging conditions. But with fresh air coming in constantly it only was passing through the refrigerant coils one time, plus sometimes the outdoor air is a lot hotter than others, so recirc is when you want the same interior air to pass through the coils more than once.
All this may go "out the window" when the exhaust fumes or worse in the outdoor air need to be excluded as much as possible.
I kind of miss the old '70's cars even though loads of them kept running long after the A/C had failed.
Regardless, I never felt alone even without a passenger, with my good buddies Max & Norm with me everywhere I went ;)
Similar to this a closed motorcycle helmet without air circulation increases CO2 extremely rapidly, within 60s it's already at really high levels. Open your visor when you stop!
Can someone provide an explanation why CO2 concentrations above 1000 ppm have such a negative influence given the fact that CO2 concentration in lungs (at rest) never falls below 10000 ppm?
Per Wikipedia, at rest 500 ml of inhaled air is diluted with ≥2500 ml [1] of residual air in lungs containing ≥40000 ppm (4%) of CO2 [2]. Other things being equal, increasing concentration of CO2 in ambient air 10x (500ppm -> 5000 ppm) would increase concentration of CO2 in the lungs after taking the breath by less than 2.5% [3].
I imagine it could easily be compensated by an equivalently minor increase of breathing rate or breathing depth.
A reasonably popular brand's product that uses an NDIR sensor revealed to me just how much the CO2 level increases each night in my two bedrooms.
One of them seems to have much worse ventilation to the extent that it reaches double the level. Opening the window slightly 24/7 keeps it low.
My fiance's chronic headaches/migraines/idk became noticeably less frequent after this change and when they do occur it's usually because the window was accidentally left closed.
Anybody who struggles with this kind of thing might want to try checking their levels. Or just open a window I guess?
One easy way to fix this for many people's bedrooms or home offices: look at your HVAC system, and there's probably an option to have the fan run all the time, even if the heat or air isn't running. Turn that on, and your home's CO2 levels will drop substantially.
Does it work the other way around? Does breathing air with 0% CO2 improve human cognitive performance? I haven't been able to find any research on the effects of lower CO2 concentrations.
For the DIYers, it's simple to get an SCD4x sensor and hook it to a pi, arduino, ESP32 etc (then use CC to create a live web interface). I did this after trying an Inkbird CO2 monitor, which gets reasonable scores in reviews and wanting a live web report in the office.
Interestingly the Inkbird and the SCD4X quite often diverge by anything up to hundreds of PPMs; I kind of back the SCD4x (on a Pi in my case) for accuracy after lots of experimentation, reading the datasheet and ensuring the correct calibration procedurs are followed (basically expose the sensors to outside air once a week).
It's also interesting how much it varies day to day in my one-person office - possibly down to how windy it is outside, even with windows closed one day it never goes about 800ppm, other days it'll hit 1500ppm by lunchtime if I don't open a window.
N.B. Quite possible the Inkbird uses an SCD4x internally, seems reasonable kit so I have no explanation for the differences in readings.
I noticed this effect really strongly at university. There was one particular lecture hall that was effectively buried in the side of a hill; I can't count how many times I had an early afternoon lecture in there (so it had been in use since 8am), where I just could not focus or stay awake. Assuming sleep deprivation was the problem, afterwards I'd head out and lie down on a bench to take a nap, only to find myself wide awake. I have no trouble taking cat-naps when I'm actually tired, leading me to eventually conclude it was CO2 / O2 in the room that was the culprit.
Not gonna happen in Germany. I don’t think I‘ve ever seen a windowless room here and it’s common to open all windows at once for a few minutes, just to replace as much air as possible:
Take a look at indoorco2map.com and you will find plenty of places in Germany with bad air measured in a crowd data collection effort. Most notably doctor‘s offices are often very bad. Many supermarkets too. Schools are not well measurable this way but academic research shows they often are at 2000-3000 ppm or even higher. (Disclaimer: I built the website/App)
I wonder if the corona times trend to WFH and jump to Teams/Zoom/etc meetings instead of physical meetings had/has a positive effect in regards to this.
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[ 4.2 ms ] story [ 98.7 ms ] threadA terrible way to make decisions.
Put it this way do you need to book a 3h meeting with your spouse to decide if to buy a house? Nope all the research and decision criteria were in advance. That final minute of making the decision is a cross check over that work.
Not to talk about the weather either.
There are so many rooms, classrooms, movie theaters and other places with poor ventilation where you just feel dizzy, or fall asleep, not knowing it was just due to lower oxygen levels in your blood. Raising awareness is the only real solution.
> Pulse oximeters have some limitations. They can only employ light at two wavelengths. Thus the devices can only distinguish between hemoglobin and oxygenated hemoglobin. When carboxyhemoglobin and methemoglobin are also present, there are two additional wavelengths required for differentiation. In the presence of elevated carboxyhemoglobin levels, pulse oximetry overestimates the true saturation of oxygen as carboxyhemoglobin binds with a higher affinity than oxygen. In the case of carbon monoxide poisoning, the absorbance spectrum of carbon monoxide is very similar to hemoglobin, which results in a falsely high level of oxygen (overestimation of oxygen saturation) ...
https://www.ncbi.nlm.nih.gov/books/NBK539754/
Why only 2?
I'm finding that pretty difficult to believe, to be quite honest with you.
And before you say "aha, carbon dioxide brain fog!" consider that I'm about a mile from the sea with a 40mph onshore breeze. This air is about as oxygenated as it gets.
In every breath you remove about 25% of the oxygen from the air in your lungs, which is why mouth-to-mouth resuscitation works, at all. Most of the oxygen is still in there.
To be clear, that 25% represents a change in oxygen level from around 21% to around 16%, so the few tenths of a percent change in carbon dioxide just isn't a huge amount.
> just due to lower oxygen levels in your blood
So my comment is in response to that.
PS. The downvote button isn't a disagree button. (Although how you can disagree with the fact that Apple watches have a blood oxygen sensor I don't know).
I was shocked to see just how fast CO2 climbs while in a room, and how just opening the window just a crack was enough to restore the room to baseline co2.
The thing runs on usb 5v so the power consumption is negligible. It also plugs in to home assistant great.
There’s a huge leap from that to the power consumption being low enough to be integrated into a smartphone, as demanded by OP.
However, this assumes the sensor would fit in a smartphone, which is not a given. And these things need air flow. And they also wouldn't work while the phone is in a bag or a pocket.
Not sure about that, at least NDIR sensors have to be at certain elevated temperature to work and they do some preheating when you turn them on from standby.
So it's not possible to just measure less often as then energy would have to be spent on heating the sensor.
They recently overhauled their lineup and replaced all Zigbee devices by Thread + Matter. Some of the new devices (mostly those who support TouchLink) have a secret pairing mode with which you can use them with Zigbee, but it's only a subset of the new products.
Uuh, seems not keeping up with social media finally backfired. That sounds horrible! So far IKEA been a great experience when it comes to HA+Zigbee stuff, and I started buying stuff relying on they'd keep just keeping up with that, really sad to hear they've changed course.
The "secret pairing mode" stuff sounds the same as currently/before though, but they only do so for a subset is new and hope they again change their mind.
If you already own the ikea hub, they secretly put thread radio in it which was just sitting unused in preparation for this range.
There are also strong downsides though, one is privacy and future cloud lock-in. Zigbee is fully local. Previous Thread standards added the option for NAT64 so that Thread devices can access the internet and there were some Thread + Matter devices that already require internet access for full functionality (IIRC some Nuki smart locks, but I might misremember). However, Thread 1.4 also adds support for Thread devices to get a globally routable IPv6 address. The Thread 1.4 whitepaper is pretty blunt about what this enables:
Simplified Cloud Integration: Thread devices can now seamlessly connect directly to cloud services, enabling remote control, monitoring, and over-the-air firmware updates.
https://www.threadgroup.org/Portals/0/Documents/Thread_1.4_F...
The fact that Thread and Matter are strongly pushed by Google, Apple, etc. should tell you enough.
Now, a TBR may simply allow you to disable NAT64 or globally routable IPv6 addresses (e.g. Home Assistant's addons), but many consumer implementations don't. E.g. the Apple TV is a Thread Border Router and does not allow disabling NAT64, so Thread devices can access the internet, send analytics, and can be cloud-controlled.
Also, the ecosystem is still pretty immature, as a result of which you can encounter issues, typically resulting in unstable device connectivity. E.g. TREL does often does not work well. Apple has some hacks to fix most of the issues, but it only works well between Apple devices. So it's generally the best to avoid combining multiple TBRs into the same network.
But I'm certainly not about to let simple IoT devices have any internet access at all. Being unable to block this on the TBR as you suggested would be mandatory for me, and not possible on AppleTV.
Better than what already exists and is deployed? I dunnno, hardware already in use always beat "hardware conceptually better but I don't have it", that's why Zigbee is better, for me. Protocols much like everything in the world, isn't correct/incorrect or universally "better", it's all down to use cases.
Personally, as someone who started to rely on IKEA providing Zigbee devices, Thread is obviously worse, because 100% of the devices I have are already Zigbee and not Thread.
It is a thermal conductivity sensor, which is a very indirect way of measuring CO2 and is very sensitive to environment factors. You only get somewhat good readings in lab conditions.
Also in my experience it’s much more accurate than that.
If you want a CO2 meter on the cheap, either wire up an optical NDIR sensor like the SenseAir S88 (22 Euro) up to an esp32, which is possibly the best sensor you can get for the money (slightly cheaper version of the sensor that the AraNet4 uses). Or if you want something standalone with a display, get the SwitchBot Meter Pro CO2 for ~50 Euro, which uses a photoacoustic NDIR, but is still miles better than the sensor in the ALPSTUGA. Can also be hooked up with HA through an ESPHome BLE proxy or with the SwitchBot Hub.
(Upd: the IKEA does have lower accuracy, with ±100 ppm instead of ±30 ppm. From the SEN63C datasheet)
You forget to mention that it is ±100ppm plus ±10% of the ambient ppm, which makes a big difference. At 1000ppm it's ±(100ppm + 0.10*1000) = 200ppm and that's only in an environment with 25C, 50% RH, and 1013 mbar. So, that does not tell you much, given that thermal conductivity is very sensitive to environmental factors.
I dont need to know the exact level, just give me green/yellow/red and make it cheap so I can have a sensor in every room
A price of 30 EUR makes this sensor really easy to pick up. For the same price as one Aranet (~180 EUR) the typical household can place a sensor in every room of the house. Which provides far more accurate readings for the whole house than just one high-end sensor in one room.
But when it goes over the safe limit it should be enough to decide to ventilate.
[1] https://ruuvi.com/air/
You'd have to raise awareness on every single person in the room and them sustain pressure to the organization in order to have proper CO2 levels in the room/organization.
And then you have to align every other person on every other organization to do this as well and hope for the best.
Or, you can do the right thing and have the state introduce regulations
But seriously, so much care needs to be taken here. OK, well "care" at least. Employers certainly would benefit from scrubbing CO2 from the air, in terms of productivity. I'm willing to bet that with central air it would be quite easy, and even with heat and AC off, lots of places still circulate the air regardless.
So the central place to scrub is already there.
But then you have other issues. Such as, will your body adapt to 8 hrs of reduced CO2, and then you become torpid and barely awake when not at work. Such a horrid thought, that is to me. And what if employers learn that the tiniest boost of O2 helps too! Now your body becomes accustomed to that, and what are the long term effects there?
I can personally envision myself being concerned. I guess the legislation could be crafted to "the same CO2 levels found just outside of downtown city core" or some such blather. Maybe even same for O2. So that you're at least pegged to something normal for the area.
Maybe that's where the state could come into play. A simple, highly accurate monitoring station which has an API to be polled.
Come to think of it, CO2 and O2 rates fluctuate during the 24 hour cycle. Trees need O2 to live, but only produce O2 during the day. And so differing amounts of light might mean up and downs in these numbers. It may be another circadian rhythm. Getting it the same as in a nearby forest, might be the healthiest thing of all.
The place to look is existing codes for ventilation. Exempli gratia: https://dos.ny.gov/system/files/documents/2020/09/2020-mcnys... (see PDF page 46). Regulations to enforce outside air being brought into human spaces already exist.
I have been in some office buildings in United States which had CO2 monitors in each meeting room, and the ventilation would engage to control CO2 below a set level. We would entertain ourselves by exhausting our lungs onto the sensors to trigger the ventilation system.
In terms of outside air, a lot of US cities I think would not benefit from that, all that much. Especially during certain parts of the day, with a lot of smog.
But regardless, all that entered my mind was "Once employers are required to add any form of scrubbing, and perhaps O2 injection, they'll over do it for optimal employee output." Regardless of whether it's helpful once the employee leaves the workplace.
I'm not against this, I'm just actually saying the regulation should be locally defined.
Scrubbing indoor CO2 is sensible only when you want to go below the outdoor CO2 level, not at levels above it.
Best solution.
The rooms being discussed here are mostly ones which would have been built before this was taken more seriously. Classrooms, older office buildings, etc.
NYC is full of buildings which would never pass any code today but are still happily occupied. It’s a trade off, I think.
You don't need to make everybody aware, you just need to make the right people aware.
As for the State... Mine mandates that nobody can use the laptop's keyboard, they must use an external keyboard so the laptops' screens can be risen to eye level.
We have the external keyboards and the risers, and nobody uses them.
The State usually finds the worst and most wasteful solution available. Only fools trust the State to solve their problems.
IIUC they also need fans. The one I have in my home has one that's actually integrated into the sensor unit.
Would be extremely cool if Apple, Samsung, and others can crack this, though I think they'd have done it already if it was easy.
The question is if oxygen levels are as good an indicator as CO2 levels... I suspect not.
You can hit this breathing by yourself in an unventilated 3x3m room (literally measured in my house).
1 https://pmc.ncbi.nlm.nih.gov/articles/PMC4892924/
i have felt bad in high co2 environments before but i have never been in a controlled high co2 environment.
Which is the point: if you're in a room trying to do deep work, that's likely a problem. I suspect submarines are all over the place here: you might be exposed to higher levels routinely but you also have regular access to chemical scrubbers and decent ventilation. I'd be fascinated to know what levels are tracked as normal.
So quite possibly an adaptive response?
Probably. ISTR that depriving a body of oxygen results in a different response than overloading the body on CO2. It's why if you completely displace all air in the room with CO2, people choke, panic, etc, but if you use Nitrogen, people just keel over dead without realising it.
We evolved to detect CO2 because that's by far the easiest thing to detect that's still a reasonable proxy for the performance of our respiratory system
https://en.wikipedia.org/wiki/Hypercapnia
It was the first time that I heard about them. These basically never happen if your body and environment are halfway decent, but they are important in exceptional situations.
But...oxygen concentration is essentially indepedent of CO2. We measure CO2 at part per million levels, whereas O2 is 20% of the air.
(In that context CO2 is surprisingly toxic given that 1000 ppm can impair mental acuity).
The goal of a gasoline engine's sensor is to accurately and precisely measure the point where O2 concentration reaches zero, so ambient air levels are not quite as relevant.
Clean air contains about 20.9% O2 and 0.04% CO2. At 2000 ppm CO2, which according to the author is bad enough to impair judgement, that's 0.2% CO2, it that CO2 is the result of respiration, it means that about 0.2% O2 was consumed, so that's a drop from 20.9% to 20.7%, a very small difference. 20.7% is not low enough to have a significant effect, the CO2 itself is the problem, not the drop in O2. And using O2 concentration as a proxy for CO2 doesn't look reliable to me: the difference is small and other things, like humidity can affect O2 concentration.
As for the sensor, O2 sensor in cars compare the O2 concentration between the outside air and exhaust gases, it needs outside air as a reference, but what you are measuring is the outside air itself, you don't have that reference.
I dont know anything about human respiration, but I know a little about chemistry and theres no reason to assume this is true. Basic stoichiometry.
According to a random article on the internet[1], nominal co2 production is 80% of oxygen consumption.
Your point appears broadly correct, just wanted to point out some faulty reasoning that could lead to incorrect results in the future.
[1] https://societymechanicalventilation.org/wp-content/uploads/...
Source?
It looks that some O2 sensors that don't require a reference have been used (titania sensors) but even though they have some advantages, they are less precise and mostly obsolete.
CO2 was measured with infrared but water also absorbed it, so you need to heat things up enough to not have water. It can be small, but not watch small.
All and all interesting stuff!
Can't you just measure CO2 "naively", then also measure rH, and use the value to grab a research-calibrated LUT to pass the CO2 value through?
Maybe if it was ambient air and not breath the humidity might not be as bad?
Article author completely ignores this for the obvious reasons.
A sensor mounted in the office will get calibrated every night when the office is empty.
But close enough for most purposes. We aren’t doing laboratory measurements here, I just want to know whether or not to open a window.
Also, already the outdoor CO2 level is 430, not 400.
Not wrong, but it is perhaps worth noting that there are already standards for proper ventilation. Generally you're looking at 5–10 cfm/person (2.5-5 L/s), depending on the facility and purpose of the room; see Table 6.2.2.1 in ASHRAE Standard 62.1 for the US:
* https://www.ashrae.org/file%20library/technical%20resources/...
Maybe set up a monitor, but if the room/facility has recently been renovated and meets modern (>2013) building codes, this 'should' have already been taken into account.
The only issue this house had was it overheated. We had glass facing south. Even in winter it instantly became too hot.
HRVs only deal with temperature, but then you have humidity that is non-controlled: moisture coming in during the summer, and getting vented out in the winter (too-dry air coming in).
ERVs handle both.
The link I pointed to is all about ventilation, so just because people ignored important component of building science, and focused on one aspect, does not invalidate it.
And while climate change is important and using efficiency to deal with it is useful, the thermal control layer is actually the least important of the four:
* https://buildingscience.com/documents/insights/bsi-001-the-p...
- Plenty of people live or work in older buildings, where are not up to standard. For example: my office probably violates the air quality sensibilities of the Victorian era, which is when it was originally built.
- Equipment breaks down, isn't operated properly, or wasn't installed correctly. Having monitors that measure air quality is an extra check. While you may not be able to get direct action upon a consumer sensor, it can help you push for action.
I've been in buildings of varying quality over the years. I've seen how it takes time to get people in to do air quality testing. Heck, I saw the government claim that the air quality was acceptable in schools during the pandemic because the schools had passive ventilation systems. That meant they could open windows. (To be fair, the air quality in most of those buildings was probably fine since that was how the buildings were designed. That said, such standards make it easy for some buildings to slip through the cracks.)
So yeah, sensors to the people!
I've been involved with the build out of several office spaces in new and old buildings. We always took this sort of thing seriously and measured each room independently for a week (many at a time) ensuring we accounted for periods of high occupancy.
This let us tune the HVAC systems to operate more efficiently, ensuring comfortable temperatures and air circulation. Every time I've seen this done there were structural deficiencies that required remediation, some times it meant adjusting duct work.
Most modern office buildings are designed to be a platform for constructing spaces, as spaces usually evolve and change between leases and tenants. They're designed to accommodate this sort of thing.
However I've found that no build out nails this the first time. It's very hard! Often times things look fine but once you get people in the space things change drastically. It requires time and effort to address.
Several of my offices had such good air that I'd prefer being there over pretty much anywhere else -- even outside on poor AQI days.
I've also found that a lot of offices don't do any of this and their air quality is noticeably poor. And lastly I've found that the oldest buildings, including schools -- and I'm talking really old -- have very good air because they are so incredibly leaky. They're usually harder to cool and heat, though.
Whenever I travel, I bring a CO2 meter with me. It’s amazing how often the air is bad. Often in unexpected places. My meter hit 3100 in an uber once. I didn’t even notice until I got to my hotel room and looked at the data log. It was a fresh, hot day outside. The uber had windows closed and AC on. I bet he had no idea - but he was driving with significant cognitive impairment. Takeoff and landing in planes are always the worst. If you get sleepy as the plane is taking off, it’s not you. The plane’s ventilation doesn’t work properly when the plane is stationary. So before a plane is in the air, they often hit 2500.
Air quality should be good everywhere. But its not. You can't tell if you don't measure it.
Then all of the sudden Satish 2012 comes along and shows serious cognitive impairment at 1000 PPM. The only studies that have replicated this involved Satish. Studies without Satish as a coauthor fail to replicate their findings.
If you think about it for a second, the levels of impairment Satish shows don’t make sense at all. You’d expect to see differences on SAT scores of hundreds of points between test centers with good ventilation and bad. You’d expect to see massive differences between regions where AC is more or less common. Or even between seasons.
It is better to have it in the HVAC system than in your phone anyhow:
https://ben3d.ca/blog/upgrading-hvac-control
ASHRAE publishes ventilation guidelines about air exchanges per hour that should keep the CO2 in a space reasonable.
I’m skeptical about CO2 actually impacting cognition to a degree where it’s noticeable.
It didn't work very well because just by virtue of being near me all the time, it didn't get a very good measure of the average room contents.
CO2 levels are locally elevated in the area where you exhale. Someone sitting at a desk with their hands on a keyboard exhaling through their nose would be producing a directed stream of elevated CO2 straight at the sensor on their wrist. Same thing if someone puts their phone on their desk.
Even with the IKEA and other cheap sensors that are becoming popular, there is a learning curve where users discover that putting it on their desk right in front of where they’re breathing produces higher numbers than having it even 5 feet away.
The false positives from having a CO2 sensor that close to everyone’s face would be causing unnecessary alarm all over.
> There are so many rooms, classrooms, movie theaters and other places with poor ventilation where you just feel dizzy, or fall asleep, not knowing it was just due to lower oxygen levels in your blood. Raising awareness is the only real solution.
If someone is falling asleep in this many different places I would suspect undiagnosed sleep apnea or another condition first and foremost. Spaces like movie theaters have very high volumes of air due to their size and commercial building HVAC has much higher standards for air circulation than even your home. If someone was falling asleep in so many different places then the most likely common theme is that person and it should be checked out!
This is another reason why putting CO2 sensors on everyone’s wrists would be a mistake: It would start getting blamed for every vague condition people experience. This has already happened with wrist-worn heart rate monitors. My friends in the medical field see people all the time who come in with vague complaints and they’ve self diagnosed as being related to their heart because they can see their heart rate now.
You also have the wrong idea about what elevated CO2 does. It doesn’t reduce the oxygen levels in your blood. It makes it more difficult for your body to expel CO2, which can produce subtle changes in many processes.
The CO2 content is a single chemical species within a mixed gas. Any air currents will cause mixing. Otherwise it undergoes diffusion which is actually a fairly slow process, although much faster in gases than in liquids.
I would imagine it's still relative unlike temperature on the wrist (which is too affected by body temp)
If you had the data, what would you do to change it? Would you recommend everyone go outside? You can do that without the data.
Would you wear your own oxygenated supply of air? You can do that without the data.
Would you make recommendations that the office should improve air quality? You can do that without personalized real-time data.
I'm not against data in general, but the idea that if only we had data we would make changes in our lifestyle is not valid. We see it all around us.
We had bathroom scales for over a century, but the data or insights didn't put a dent in the obesity epidemic.
You're right about "the problem will solve itself", but it isn't the data that will help to solve the problem, it's creating a simple and obvious solution.
A friend has a start-up in the commercial air quality space which solves for this problem (in some ways). But the benefit isn't the air quality, it's the cost of maintaining the healthy levels required in commercial buildings. Air quality is the secondary benefit of reduced electricity demand in air circulation.
IKEA now has a remarkably cheap ($35) air quality monitor that measures CO2 as well as PM:
https://www.ikea.com/us/en/p/alpstuga-air-quality-sensor-sma...
I don't have one yet but plan to pick one up soon. A CO2 sensor alone from Adafruit is $50+, though that one is more precise. I bought it a while ago and it's still sitting in my todo bin.
Flu and other air transmited diseases should be treated as a workplace injury, with proper compensation!
I want this implemented to fullest, preferably with full hazmat suit. Yet more reasons to support work from home.
While true, your comment implies that infections through air are not important/critical. This includes COVID-19?
The first needs to occasionally see new threats to stay up to date and healthy. The second will not like the constantly restricted airflow.
Why that matters? You need good ventilation regardless, but instead of just thinking of CO2, try to minimize compounds in your air by selecting things for the room that smell less and off-gas less.
I am suspicious of 0.1% having a significant effect though, given oxygen is around 20% and we naturally exhale a couple of percent CO2.
So in practice the oxygen level can never drift meaningfully far from the atmospheric pressure, whereas carbon dioxide easily can because the pressures involved are so low.
This original study has been used to market these CO2 monitors for years, but the evidence is quite thin and doesn't support a strong effect. It seems likely that there is a small effect, and it has been wildly exaggerated thanks to a small study with N=22.
Robert Boyle describes Drebbel’s use of a “chymical liquor” to refresh the air.
“Paracelſus, indeed, tells us, that "as the ſtomach concocts the aliment, "and makes part of it uſeful to the body, rejecting the other; ſo the "lungs conſume part of the air, and reject the reſt." Whence, according to him, we may ſuppoſe a little vital quinteſſence in the air, which ſerves to refresh and reſtore our vital ſpirits; for which purpoſe, the groſſer, and far greater part of the air, being unſerviceable, it is not ſtrange that an animal ſhould inceſſantly require fresh air. This opinion, indeed, is not abſurd; but it requires to be explain'd and prov'd: beſides, ſome objections may be made to it, from what has been already argued againſt the transmutation of air, into vital ſpirits. Nor is it probable, that the bare want of the generation of the uſual quantity of vital ſpirits, for leſs than one minute, ſhould be able to kill a lively animal, without the help of any external violence. And, upon this ſuppoſition, Cornelius Drebell, is affirm'd, by many credible perſons, to have contrived a veſſel to be row'd under water: for Drebell conceiv'd, that it is not the whole body of the air, but a certain ſpirituous part of it, that fits it for reſpiration; which being ſpent, the remaining groſſer body of the air, is unable to cheriſh the vital flame reſiding in the heart. So that, beſides the mechanical contrivance of his boat, he had a chymical liquor, which, by unſtopping the veſſel wherein it was contain'd, the fumes of it would ſpeedily reſtore to the air, foul'd by reſpiration, ſuch a proportion of vital parts, as would make it again fit for that office; and having made it my buſineſs to learn this ſtrange liquor, his relations conſtantly affirm'd, that Drebell would never diſcloſe it, but to one perſon, who himſelf told me what it was.“
https://sourcelibrary.org/book/philosophical-works-vol-2-boy...
I see this pop up on X every few weeks. Is the concern about this really based on actual science? Is there empirical data proving people are less productive or are damaging themselves as a result of heightened CO2 levels? And I don’t mean observational epidemiology studies.
So perfect for HN, you can obsess over tech and how to measure it endlessly and overhype the significance to trick yourself into thinking you're doing something useful.
You get to have your cake and eat it, no wonder everyone loves this topic.
(Also if you're a doomer type you can link this in with rising atmospheric co2 levels for extra points)
Meanwhile in France we heat classrooms by stacking 35 kids in a confined space. It saves on heating, plus condensation that makes windows opaque helps pupils concentrate on the blackboard, as teachers said during my childhood.
That sounds like something you made up to justify your beliefs…
The average male height in France is 178.60 cm, while in Australia it is 178.77 cm:
* https://worldpopulationreview.com/country-rankings/average-h...
Some sources even have France being higher than Australia:
* https://ourworldindata.org/human-height
But also bear in mind that regardless of "are we operating at max effectiveness", OSHA sets a legal limit of 5000ppm in a workplace, and that's about _safety_.
This article is talking about keeping levels below 1000 which is a very high standard IMO. But if you are in a poorly ventilated home office you could easily hit 3000. At that point you are closer to "illegal in the US" than "earth's atmosphere".
So yeah even if you are unconvinced about micro-optimising your CO2 levels there's a very long established argument in favour of at least paying _some_ attention to it.
The real problem is offices and meeting rooms where you have 10 people in a small box for hours and windows that don't open.
I live on a noisy street so I don't usually want to do that, if I open a window at the back and keep internal doors open it will stay reasonable but significantly elevated.
So yeah I think the lesson here is you probably need to buy a sensor, different homes are gonna differ.
My home is quite small (probably 80m²) and has literally zero ventilation built in (even in the bathroom!). I live in Switzerland where it's traditional to actively ventilate your home twice a day. But that doesn't do anything for CO2. Also it's such a fucking waste of time lol. Looking forward to moving into a modern building.
So maybe a few leaky cracks are enough that when you open a window you get a bit of a through-draft.
Also go for a walk, unless you live in a hellhole.
In a bedroom it might be worse than the elevated CO2 problem.
Is that really dramatic, or just the reality that needs to be considered in a cost-benefit analysis? Are you a hay fever truther?
I'm certain many people are sleeping in similar conditions without realising and ventilating their rooms properly or leaving the door open.
Also, moved all of my lovely oxygenating plants like lillies out of the room because they are toxic to kitty.
It absolutely does.
>I'd just accepted for the longest time that waking up groggy with a slight headache and tired was the norm until I put a CO2 monitor in my room. With the door closed, it climbed up to 1500ppm in under an hour.
Same experience here. Opening windows just a bit totally changed my sleep quality.
You'd think (hope) if there was a big effect here on performance, the relatively cheap/easy solution of maintaining lower CO2 would be standard. I know people think of the military as dumb grunts who you don't want to think, but he was one of the four department chiefs onboard (Weapons, Nav, I forget the others) and they have pretty substantial responsibility to make decisions on their own.
Along the way they’ll either learn about or accidentally mitigate other ills like radon, nitrous oxide from stoves, diesel particulate’s impact on test scores, etc.
It kind of reminds me of the old joke where a drunk is looking for his keys under a street lamp even though he dropped them in a dark corner of the parking lot.
CO2 is just a tip as office or home is toxic environment anyway. Plastic (e.g. carpets), formaldehyde in furniture, air fresheners… add home office and cooking at home (-> small carcinogenic particles)…
If you start reading How not to die by Michael Greger, you find out that dust, soda and sitting - not CO2 - are real killers…
It's similar to how people think sharks and airplanes are the biggest killers - when in reality it is coconuts, mosquitoes, and motorcycles.
Dust is much more likely to just settle on the ground and be kicked back up than it is to move all the way to the purifier to get stuck in the filter.
Maybe it's not just the air but also the multi-hour meetings that drive people to a sense of "oh god let this finally end now", which leads do decisions that fall short.
Also, take walks. I am lucky to be able to walk to and from work and it helps immensely.
This post evaluates to 99% AI generated.
That's valuable in at least three different ways: public education, showing that most of the articles are still human-written which can be easy to forget about sometimes, and as an easy way to cross-validate my intuition when flagging something as AI-generated without having to manually run Pangram.
I despair a little bit about how many HN voters either seem to want to read slop or don't understand when they're reading it. This post is obviously AI generated from the first paragraph on, and still has 480 votes.
They train a classifier on human text paired with AI-generated versions of the same documents. Dataset scale is comparable to LLM pretraining sets.
Generally it’s a miracle to me so many people survive traffic on public roads, statistically.
>Cars aren't hermetically sealed
I can agree with that completely.
Not my downvote btw, corrective upvote instead :)
Naturally I often wonder if many people know what Hermetically sealed is all about to begin with.
I do a bit of that in the lab when I seal flammable reference materials inside glass ampules using a torch. But it's not the sealing that counts, it's the technique ;)
If you check Wikipedia, you may notice that the terminology is older than the internet in every way.
Specifically they do not show awareness that it really means "sealed in such a way that it can't be figured out. As if by God. Not just any God but the ancient Roman God Mercury, otherwise known as Hermes when worshipped by the ancient Greeks."
Now I can only assume you have never been in a new 1960's WV beetle when all windows and the manual vents were shut (they didn't have A/C) when somebody slammed the door. You eardrums would remember it if so.
They're just not that sealed up.
At the extreme was "MAX" which most people didn't realize was "recirculate" unless they read the owner's manual in those cases where it was well documented. The next notch over was "NORM" which as the name implied was intended to be the "normal" setting except under more challenging conditions. But with fresh air coming in constantly it only was passing through the refrigerant coils one time, plus sometimes the outdoor air is a lot hotter than others, so recirc is when you want the same interior air to pass through the coils more than once.
All this may go "out the window" when the exhaust fumes or worse in the outdoor air need to be excluded as much as possible.
I kind of miss the old '70's cars even though loads of them kept running long after the A/C had failed.
Regardless, I never felt alone even without a passenger, with my good buddies Max & Norm with me everywhere I went ;)
https://en.wikipedia.org/wiki/Carbogen
I imagine it could easily be compensated by an equivalently minor increase of breathing rate or breathing depth.
[1] https://en.wikipedia.org/wiki/Gas_exchange#Alveolar_air
[2] https://en.wikipedia.org/wiki/Breathing#Composition
[3] 5/6 × 40000 ppm + 1/6 × 500 ppm = 33417 ppm; 5/6 × 40000 ppm + 1/6 × 5000 ppm = 34167 ppm; 34167 / 33417 = 1.0225
One of them seems to have much worse ventilation to the extent that it reaches double the level. Opening the window slightly 24/7 keeps it low.
My fiance's chronic headaches/migraines/idk became noticeably less frequent after this change and when they do occur it's usually because the window was accidentally left closed.
Anybody who struggles with this kind of thing might want to try checking their levels. Or just open a window I guess?
Interestingly the Inkbird and the SCD4X quite often diverge by anything up to hundreds of PPMs; I kind of back the SCD4x (on a Pi in my case) for accuracy after lots of experimentation, reading the datasheet and ensuring the correct calibration procedurs are followed (basically expose the sensors to outside air once a week).
It's also interesting how much it varies day to day in my one-person office - possibly down to how windy it is outside, even with windows closed one day it never goes about 800ppm, other days it'll hit 1500ppm by lunchtime if I don't open a window.
N.B. Quite possible the Inkbird uses an SCD4x internally, seems reasonable kit so I have no explanation for the differences in readings.
https://www.ikea.com/au/en/p/alpstuga-air-quality-sensor-sma...
Stoßlüften.
but then germany hasn't been doing so well lately, and people who do most of their work outside should also be doing better...
The worst thing is, I'm pretty sure humans are starting to mimic that cadence too...
https://www.pangram.com/history/c410d4b4-abfd-4ca0-b52d-db0d...
Feels like I wasted time reading bullshit.