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 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.
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.
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 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.
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.
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.
(Upd: the IKEA does have lower accuracy, with ±100 ppm instead of ±30 ppm. From the SEN63C datasheet)
Worse specs? Sure. Worse value? I don't think so. Worse accuracy? Perhaps not either.
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.
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.
You can find a comparison of the IKEA sensor with other affordable sensors here:
(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.
No, it's not. You generally want to ventilate an office when you reach 1000ppm, but then the IKEA will often warn you already at 700ppm. 700ppm is fine.
"Generally" is a vibe measurement to begin with. You won't notice any difference at all between 700ppm and 1000ppm. It's once you start hitting 2000ppm you are getting noticeable brain fog.
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 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.
Don't by the ALPSTUGA for anything but very rough trends, there are much better affordable options.
I notice that thinking becomes less clear when going above 1000ppm, so I let HA send a notification at 1000ppm. With ALPSTUGA it would send already at 700ppm. By the way, above 1000 the divergences become even larger due to the inaccuracy also being 10% of the ambient CO2 concentration (in optimal circumstances, probably larger IRL). So, suppose you want to be notified at 2000 ppm, the IKEA sensor might already do so at 1500 or 1600 ppm and it continuously drifts, so it's not like you can use a particular offset.
Besides that, what's the point? There are much better meters in a similar price class. As an additional benefit, they can last months or up to a year on two AA batteries.
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, e.g. some of the lights) 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.
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.
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.
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...
which draws 0.5W. This 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.
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 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).
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.
It is not that complicated. You need to introduce CO₂ threshold levels that make sense from a medical standpoint. Then you need to enforce them in the same way other basic environmental regulations or worker rights are enforced in regions of the world where these work.
The main question is: If your workplace, city, whatever forces you to work or live in an harmful/unhealthy environment, do you have any realistic course of action to improve the situation? In the US you would call this (gasp) regulation, I would call it a basic human right.
If we talk about stairways, nobody complains about building regulations that mandate handrails. CO₂ levels are not totally different.
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.
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.
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) ...
I don't think that's safe to assume at all, for two reasons:
1. CO2 has effects on the human body of its own that aren't simply a lack of oxygen, and vice-versa. [0]
2. The baseline proportions involved aren't close, so even doubling CO2 isn't going to show up easily as a large swing in in oxygen%.
For example, the article references a study where the CO2 proportion going from 0.04% -to 0.25% correlates to mental problems.
Even if the watch could sample atmosphere directly, is it sensitive enough to detect a shift from 21.00% -> 20.79% oxygen?
As it's estimating oxygen in the owner's blood, it might not detect anything different at all... not if the owner's body has already compensated by breathing harder or by "underclocking" their brain to make dumber decisions.
> 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.
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 do feel impaired around 1000ppm. I get headaches. At home I got a few Air Gradient Ones (no affiliation, but they are great) and connected those to my Home Assistant to turn up the ventilation in stages (above 650ppm go up, above 800ppm again, at 1000ppm max). I also do this for the bedrooms, cause in the night it goes up too.
The article talks about "within the hour". With four people in my living room doing normal things it jumps within 20min to around 1000ppm. If I am wrestling with my kids much sooner.
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.
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 (still arguably justified given the studies mentioned). 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 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.
It's peak HN meme material because 1) it (allegedly) 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 numbers and 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 Australians 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 me 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 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.
Ok, fair points, including the sister comment, it's likely not a drop in O2 levels.
But then why can we see problems with concentration in studies of people in poorly ventilated rooms, but not replicate that when just adding CO2 to normal air? What is the CO2 that we can measure in meeting rooms actually a proxy for?
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 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.
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.
One key difference is that submariners are rigorously trained to operate effectively in less-than-ideal environmental conditions, whereas Bob from accounting probably is not.
Two tips: if you want a stationary CO2 meter in a room, you can make one very cheap with a SenseAir S88 sensor (22 Euro) and hooking it up to an ESP board. Flash ESPHome and you can get live statistics in your Home Assistant dashboard. The S88 is a pretty good optical NDIR Sensor that auto-calibrates by putting it in the outside air or in a well-ventilated room every N-days (N is in the data sheet). A bit more info about hooking up the S88:
If you want something with a display that works on batteries without spending over 200 Euro for an AraNet, the SwitchBot Meter Pro CO2 is pretty good option. It is regularly on offer below 50 Euro. It uses photoacoustic NDIR, but does not deviate a lot from the S88. You can use it without a SwitchBot by configuring it with a phone on Bluetooth. The meter works on external power and battery, but even when on battery, you can set the reporting interval to 5 minutes, which is good enough in practice. The meter broadcasts the measurements with Bluetooth LE, so if you want to get the data in Home Assistant, you can place a ESPHome Bluetooth LE Proxy in the vicinity [1]. This is an ESP32 flashed with ESPHome that listens on Bluetooth LE advertisement and forwards them to your HA instance over WiFi. Of course, you could also get the SwitchBot Hub, but what is the fun in doing that? :)
I would avoid the Ikea ALPSTUGA, it uses a thermal conductivity sensor, which is a very indirect method for measurements and it's often several hundred ppm off.
Looks like it's increased in price unfortunately but I like the idea, it's basically just what you would do as a DIY project but ready built. So you can either use it like a normal commercial product, or you can just fork the ESPHome config that's on GitHub and flash it exactly like any normal ESPHome project.
Thanks for mentioning that, last week I got 2 SwitchBot hub mini, 3 temperature sensors each, for 70€ total, they are really neat. Even put one in our fridge, I didn’t expect the signal to pass but it’s working :)
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.
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.
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...
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.
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:
i literally had a co2 sensor for my engineering team last fall cause the space was so poorly ventilated. just measuring it continuously radically changed how everyone approached using the space packing wise and ventilation. smelled better too :p
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.
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.
My previous employer had dogs shit on carpets, without proper desinfection! Just smearing excrements into carpet, waiting for it to dry out, so it can go airborne!
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. HVAC maintenance, cleaning, and filters. Washable allergen covers for things like pillows and mattresses.
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.
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 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.
I also use my Aranet everywhere. The nice thing is you quickly develop a feel for when you need to ventilate spaces you know so you don’t need it there anymore. I also developed a feeling for new (to me) rooms a bit.
I once woke up with the fam in a hotel with airco at 5500 ppm. It is then that I learned the airco does not blow fresh air (logical after thinking about it).
> 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.
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.
Goes a long way to prove that industrial air conditioning is absolutely abysmal. If air conditioning actually worked satisfactorily, opening a window should never be necessary unless you want the cold waft of air, while the air conditioning actually delivered high-quality, low-CO2 air without smell.
Instead any room at > 20% capacity is quickly filled with CO2 and the putrid smell of bad mouth and body odour.
I get it that perfect ventilation would be way more expensive, but at the current level it is just bad, and the windows are sealed shut. It does not make sense from a human perspective.
This article is rated 100% on my AI smell meter, making it less trustworthy despite convincing arguments.
For instance, I'm now really only sure that author measured a 2000 ppm CO2 in a meeting room once. Everything else could just be LLM trying to invent convincing argument.
I tend to agree with this observation. I started taking my evening calls (6:30 to 10:30 PM everyday) from my terrace in open air and my overall fatigue became quite less and I feel quite less tired compared to earlier time when I used to take these calls from my room.
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.
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.
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?
I remember some years ago after coming from work at 6 pm I was dead tired at home thinking it was due to hard work during the day. Then one summer day decided to code side projects on my balcony and I was building until midnight full of energy.
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.
The really uncomfortable part is that 1000 ppm isn’t that far off from how EARTH will be. A terrifying scenario that will be like Total Recall with people clamoring for and paying for fresh air. Those that can’t will be permanently in a stupor.
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.
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!
open a window, wait, ok, ok, turn up the , wait, no, ummm, hmmmmm
re, re, no forget that, hmmm
anyway, as a person with a strong interest in civil engineering, systems, and the subset of air handling, I can say that there has long been disenting arguments about how things are built,that have been ignored due to cost, which are large in terms of internal volumes required, and the intractable issues around, noise, filtration, heating/cooling and maintenance.
And as the climate warms, and in many areas pollution increases , the inadequate methods used to "calculate" requirements, get further from real world needs.
You could try throwing a desk through a window, but as that is one of the things the planners and engineers have antisipated, it will prove to be surprisingly difficult.
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.
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.
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.
[1] https://ruuvi.com/air/
(Upd: the IKEA does have lower accuracy, with ±100 ppm instead of ±30 ppm. From the SEN63C datasheet)
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.
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.
You can find a comparison of the IKEA sensor with other affordable sensors here:
https://danieldk.eu/hardware/smart-home/ikea-alpstuga
(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 a green/yellow/red LED and make it cheap so I can have a sensor in every room
and if sometimes you ventilate a bit sooner than required, at 700, what?
businesses will not put $200 meters in every room
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.
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.
Don't by the ALPSTUGA for anything but very rough trends, there are much better affordable options.
Also in my experience it’s much more accurate than that.
Besides that, what's the point? There are much better meters in a similar price class. As an additional benefit, they can last months or up to a year on two AA batteries.
ALPSTUGA is an inferior product.
"oh no I am getting too much fresh air"
I get your point but come on.
They recently overhauled their lineup and replaced all Zigbee devices by Thread + Matter. Some of the new devices (mostly those who support TouchLink, e.g. some of the lights) 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.
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.
It can't be much, since the Aranet 4 can run for years on 2 AA batteries.
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.
The main question is: If your workplace, city, whatever forces you to work or live in an harmful/unhealthy environment, do you have any realistic course of action to improve the situation? In the US you would call this (gasp) regulation, I would call it a basic human right.
If we talk about stairways, nobody complains about building regulations that mandate handrails. CO₂ levels are not totally different.
IIUC they also need fans. The one I have in my home has one that's actually integrated into the sensor unit.
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.
> 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?
1. CO2 has effects on the human body of its own that aren't simply a lack of oxygen, and vice-versa. [0]
2. The baseline proportions involved aren't close, so even doubling CO2 isn't going to show up easily as a large swing in in oxygen%.
For example, the article references a study where the CO2 proportion going from 0.04% -to 0.25% correlates to mental problems.
Even if the watch could sample atmosphere directly, is it sensitive enough to detect a shift from 21.00% -> 20.79% oxygen?
As it's estimating oxygen in the owner's blood, it might not detect anything different at all... not if the owner's body has already compensated by breathing harder or by "underclocking" their brain to make dumber decisions.
[0] https://en.wikipedia.org/wiki/Asphyxiant_gas
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.
I don't think it's too far-fetched for a quarter of that to cause subconscious cognitive effects, that could be measured in tests.
The article talks about "within the hour". With four people in my living room doing normal things it jumps within 20min to around 1000ppm. If I am wrestling with my kids much sooner.
In offices companies often neglect it.
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.
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 (still arguably justified given the studies mentioned). 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.
https://pmc.ncbi.nlm.nih.gov/articles/PMC4892924/
So perfect for HN, you can obsess over numbers and 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.
Also go for a walk, unless you live in a hellhole.
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.
But then why can we see problems with concentration in studies of people in poorly ventilated rooms, but not replicate that when just adding CO2 to normal air? What is the CO2 that we can measure in meeting rooms actually a proxy for?
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.
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.
https://danieldk.eu/hardware/smart-home/esphome-senseair-s88
If you want something with a display that works on batteries without spending over 200 Euro for an AraNet, the SwitchBot Meter Pro CO2 is pretty good option. It is regularly on offer below 50 Euro. It uses photoacoustic NDIR, but does not deviate a lot from the S88. You can use it without a SwitchBot by configuring it with a phone on Bluetooth. The meter works on external power and battery, but even when on battery, you can set the reporting interval to 5 minutes, which is good enough in practice. The meter broadcasts the measurements with Bluetooth LE, so if you want to get the data in Home Assistant, you can place a ESPHome Bluetooth LE Proxy in the vicinity [1]. This is an ESP32 flashed with ESPHome that listens on Bluetooth LE advertisement and forwards them to your HA instance over WiFi. Of course, you could also get the SwitchBot Hub, but what is the fun in doing that? :)
I would avoid the Ikea ALPSTUGA, it uses a thermal conductivity sensor, which is a very indirect method for measurements and it's often several hundred ppm off.
https://esphome.io/components/bluetooth_proxy/
Looks like it's increased in price unfortunately but I like the idea, it's basically just what you would do as a DIY project but ready built. So you can either use it like a normal commercial product, or you can just fork the ESPHome config that's on GitHub and flash it exactly like any normal ESPHome project.
https://screek.io/ https://shop.screek.io/products/sco-b
No recommendation though, I haven't tried them.
Will look at adding the CO2 monitoring
Generally it’s a miracle to me so many people survive traffic on public roads, statistically.
This post evaluates to 99% AI generated.
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!
The first needs to occasionally see new threats to stay up to date and healthy. The second will not like the constantly restricted airflow.
It's on my desk and I can confirm, opening the window if it gets orange helps a lot with thinking.
Some days in the morning it shows red and I barely can't think or get awake. Opening the window and it changes instantly.
Stoßlüften.
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
After testing a variety of AQI sensors, I ended up acquiring multiple Airthings-branded devices.
They provided the best mix of CO2/VOCs/PM sensors in a single device with a decent enough app.
There may be better options now, but I have these at both home and office.
Highly recommend doing the research and learning about the environments you’re in, especially if you have little ones at home.
Edit to add: opening windows is usually the easiest/best solution!
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.
Natural CO2 in a room probably correlates strongly with other things given off by humans... Farts, water vapour, viruses, etc.
The effect needs to be properly understood before totally redesigning the nations ventilation systems on a possibly wrong premise.
I once woke up with the fam in a hotel with airco at 5500 ppm. It is then that I learned the airco does not blow fresh air (logical after thinking about it).
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.
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...
For instance, I'm now really only sure that author measured a 2000 ppm CO2 in a meeting room once. Everything else could just be LLM trying to invent convincing argument.
The worst thing is, I'm pretty sure humans are starting to mimic that cadence too...
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?
In most office buildings (towers) that's impossible. You have to deal with what the A/C gives you.
https://science.nasa.gov/earth/explore/earth-indicators/carb...
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.
Support European!
https://aranet.com/en/home
Also, take walks. I am lucky to be able to walk to and from work and it helps immensely.
Not to talk about the weather either.
A 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.