[sergioisidoro]

I bought a CO2 monitor, and although the effects of CO2 in cognition and energy levels are debatable[1], it shocked me and raised awareness to how poor my indoor ventilation is.

We live in a small apartment, and just being 30 min with 2 people in the room raises the CO2 ppm from 400 to >1000. Opening a window quickly lowers it. Never-mind doing some light activity like yoga or similar.

So if we want to do something, I think the first step is really to get visibility to the problem, especially to the costs of the problem (productivity, public health, sick leaves, etc).

[1] at the levels found in my apartment

[isp]

> So if we want to do something, I think the first step is really to get visibility to the problem

A sensible first step would be to very visibly display CO₂ monitors in buildings (e.g., throughout office buildings, schools, etc)

Once the CO₂ levels become visible, this in itself creates an incentive to improve.

Related from UK (2021): "All schools to receive carbon dioxide monitors" - https://www.gov.uk/government/news/all-schools-to-receive-ca...

[bsenftner]

In Japan, it is common to see CO₂ monitor displays outside contained meeting spaces, such as theaters.

My wife purchased an Aronet CO₂ monitor, and I took it with me on a business trip last week. The CO₂ while on the flight was in the 3000's range. The CO₂ at my client's office was in the mid 2000's range, as well as the hotel. Opening the hotel window the allowed 2 inches reduces CO₂ to the 600 range in 10 minutes, but the client's office windows do not open, and of course neither do the airplane windows.

I've also noticed when working indoors or when driving, if the CO₂ is above 1500 I get drowsy, so the degree it is no longer responsible driving a car.

Air safety: are we going to fight a moronic battle over this too?

[blkhawk]

I have had a self-build CO2 monitor for several years now and I find the airplane example Surprising.

AFAIK the air in a Plane is cycled out too fast for that amount to develop. Maybe the Lower air pressure was the cause? Since it was portable it was probably the NIR type? If its not measuring all the time it might also be the heater type - I am really not sure how that type would deal with low pressure. Or was is the "eCO2" type - in that case well I doubt you get anything out of that thing in a plane except a high number.

One thing I noticed is that CO2 seems to "flow and pool" in certain places as it seemingly "rains" down and the room is "filled" from the bottom up. A Table for instance might develop a layer that is thick enough for my meter to hoover it up (it has a fan).

[Retric]

Local passenger density is going to play a role here venting air from low density first class areas isn’t going to do much. Similarly as you mention air flow is important as being in the middle of a large row could have vastly worse airflow than other areas.

So, I could easily see the aircraft venting mostly 700ppm air while some areas hit 3000 ppm internally.

[blkhawk]

3000 ppm is directly breathing at the meter - at least with mine it is.

[giraffe_lady]

No, there won't be any battle. If there were going to it would have been during covid, with improved indoor ventilation being one of the major components of an in-depth mitigation strategy.

There was no meaningful attempt or debate about changing ventilation standards then when it would have tangibly saved lives, there certainly won't be now.

[marcosdumay]

The covid years were crazy. People kept cleaning everything with all kinds of poison (thank god somebody published early that alcohol at 70% is enough, otherwise I think we would see people dropping dead from too much poison), that was known to be useless by around April 2020, and yet everybody actively refused to talk about indoor ventilation.

And most were the same people repeating the "are you for or against science?" line.

Crazy years, dominated by completely random propaganda. Discussions on calmer times follow different rules, and if nobody decides to spend a lot of money stopping it, it can follow rational, evidence based lines.

[giraffe_lady]

Very cynically I think it was rejected early and high up because it simply would have required a top-down decree that large corporations spend an astounding amount of money for the wellbeing of their workers. As a society we've basically ruled out interventions of that sort by now, and it would establish/reinforce the belief that companies are responsible for the health of their workers.

Whereas personal-domain actions like sanitizing and masking cost companies basically nothing and reinforce the mindset that covid mitigation is an individual responsibility and so the consequences from having it are an individual burden. It doesn't even matter if they work or not, from this perspective, which explains why pointless things like sanitizing and QR menus persisted so long.

[cameldrv]

I think it was a combination of things.

1. Inertia: Sanitizing and disinfection was what was recommended in March 2020. Even masking was actively discouraged until later.

2. "We have to do something." "This is something."

3. Handwashing/hand sanitizing and sanitizing surfaces are visible actions that reassure some people. Ventilation and filtration improvements are generally not visible.

4. Ventilation and filtration improvements are expensive and, for an institution, require certified professionals to design and implement. There aren't enough of these people and not enough equipment to implement this for every building in a timely manner. Handwashing and clorox wipes are cheap and anyone can use them.

Personally I think that COVID is likely going to be with us for some time to come and will cause significant disability as people get infected repeatedly. I think eventually we will see significant uptake of ventilation/filtration improvements.

[robocat]

Less cynically, there were no filtration units or HEPA filters available because demand far outstripped supply. It would be interesting to know how fast production could have been increased (face masks took a while).

[anonymouskimmer]

> otherwise I think we would see people dropping dead from too much poison

At least one person (with multiple chemical sensitivity) committed suicide (medically-assisted) because the sanitation and smoking in her apartment complex during COVID made her life so miserable she didn't want to live anymore. https://www.ctvnews.ca/health/woman-with-chemical-sensitivit...

[highmastdon]

Very cynical take: if there would’ve been a change in laws to increase ventilation, it would drastically reduce any illness, like flu, the common cold and other airborne viruses. This would lead to a decrease of taking vaccines for those, which would upset the big pharma.

Nearly any blanket-like measure was blocked by those. E.g. Vitamin-D supplementation, of which we know almost every indoor worker has a deficit of in western countries. Never ever was this prompted by govs even though there’s a clear correlation between deficit and deaths (not causation) and it has even antiviral properties (I suggest you to look into MedCram YouTube channel on videos around the first year of COVID where they go over many case studies on potential treatments)

[btbuildem]

Seems like yes, we are. A good proportion of people abhor change, even if it would make their lives better.

[dylan604]

>if the CO₂ is above 1500 I get drowsy, so the degree it is no longer responsible driving a car.

so the old adage of rolling down the window when driving might actually have some factual logic to it. of course, people are only considering that when at the extreme end of trying to stay awake from already driving past safe limits, but it could easily make a long haul trip more bearable by remembering to crack the window at intervals. then again, if you're riding with my buddies, you were already having to crack the windows at intervals, but for other reasons.

[Nition]

Also useful is having the fans set to fresh air rather than recirculate.

[radlad]

> The CO₂ while on the flight was in the 3000's range.

I always assumed they intentionally messed with oxygen in the cabin to "relax" travelers.

Anecdotally, I have often experienced a sedative effect on airplanes that I do not ever experience in land vehicles.

[mlsu]

In general, anecdotes about "they raise the oxygen levels in [x] to induce [y]" are completely false. I've heard this about airplanes and casinos.

For one, it's really difficult/energy intensive to increase the level of oxygen in a space. Second, it's very very difficult to purify oxygen -- because oxygen oxidizes stuff. Even if you could do that, raising the level of oxygen is extremely dangerous, because it radically increases flammability of things and makes fire much worse. For an example of this: Apollo 1.

[tesseract]

Well, there's less of it, since typical airliner cabin pressure is equivalent to being at 8000ft altitude or so. Do you typically spend long durations driving in the mountains?

[weaksauce]

the oxygen levels in airplanes are not high because they only pressurize the cabin to be about a 7000' pressurization. that's roughly equivalent to a lot of mountain town altitudes... think flagstaff.

[bolangi]

About air safety: the pilots cabin has much better quality air than the passenger section.

[hammock]

When driving, does running the air (not on recirc) not exchange enough air?

[bsenftner]

Opening a car window or running air not on recirc immediately drops the readings to safe levels. I also noticed when in the Uber returning from the airport, the air was in the high 3000's and I explained to the driver, he opened all the windows and I think I scared him a bit.

[schiffern]

Note that, to minimize pollution from vehicle exhaust, you want to set your air to "recirculate". Unsurprisingly, the roadway is where vehicle pollution is most concentrated!

https://www.latimes.com/science/sciencenow/la-xpm-2013-sep-1...

Usually what I do is set it on recirculate, and then every ~10 minutes I periodically "flush" the CO2-laden interior air for a minute or so. Ideally, I'm able to do this "flush" when I'm away from a major city or high-traffic road (and not when driving behind a soot-spewing diesel bus/semi/garbage/cement truck).

I wish there were some way to automate this logic!

---

(and yes, my dear observant reader, if I could recirculate "only" 90% of the exterior air it would achieve the same steady-state result, but modern cars got rid of the "slider" that lets you select a percentage of recirculate air... ::sigh::)

[Retric]

That works for particulates but not gasses like carbon monoxide. You’re better off having the best filters you can get supplying fresh air constantly rather than constantly recirculating stale air.

[sizzle]

I always crack my sunroof an inch and pull the shade forward go get some fresh air in recirculate mode so I’m not picking up crap from the engine bay.

How does the fresh air mode on the car not pull in CO gases from the engine bay? Surely a pleated cabin filter is not enough to stop it? Or does the air come from the manifold air intake?

[XorNot]

Before I stopped being in offices I was looking for a portable CO2 monitor to take into meetings to see how quickly we ended up at 1000+ppm. The tendency to overcrowd meeting rooms I was convinced was basically a driver in devaluing them - the CO2 is going up and up and up and people's cognition is slowly ebbing alongside regular old fatigue.

[morkalork]

I always blamed it on heat accumulation, after stuffing all those bodies, laptops and even old inefficient lighting/projectors into a confined space it gets way too warm, then the body slows down to compensate.

[sumek83]

Belgium is making it obligatory from later this year, including gyms, restaurants, bars, etc

[LeonM]

I don't understand why you are being downvoted, you raise a good point.

Based on some HN comment from a while ago I invested in a CO2 meter (they are still quite expensive for some reason). And I share the same experience, CO2 levels can raise rapidly indoors, but simply turning on ventilation or opening a window very quickly lowers CO2 contents.

Using the meter I found CO2 levels in my bedroom can become quite high at night. So I improved the ventilation in my bedroom, and in my case it helped me to achieve better sleep.

[anonyfox]

… and people make joke about us Germans need to do „stosslüften“ (opening all windows in parallel to get fresh air in fast).

also, are there really people that can (or even prefer!) to sleep with closed windows?! Only with AC blasting, right?

[balfirevic]

Yes, that's the only way to have nice cozy temperature throughout the year. Heating will be on during large part of the year, but during the summer AC will be on. Just working gently, though, no blasting.

I'd love to have ventilation with heat exchanger, but that's basically unheard of where I live.

[cultureswitch]

I can't sleep with either AC, simple ventilation or windows open. Too much noise. In rural environments too, just a single cricket is capable of keeping me awake.

Sometimes in very hot weather I do leave the windows open at night but it's due to heat, not air quality.

[heipei]

Try sleeping with earplugs. I started doing it out of necessity, and it was awkward at first, but once I got used to it was really life-changing. Sleeping with plugs in feels like being embraced by silence and darkness, so much so that you can sleep the whole night through and feel more refreshed in the morning.

[aidenn0]

Aside from urban noise, I don't sleep well if an open window is too close to my bed because I end up with congested sinuses.

[robocat]

> I end up with congested sinuses

Always? I am fine if the air is fresh (e.g. sea breeze onto shore), but tend to get sniffles in city or countryside environments.

[aidenn0]

When it's humid I don't, but dry air invariably does it to me.

[switchbak]

Some new buildings use an HRV system which circulates fresh air in while recovering some of the heat of the exhaust air.

[GloriousKoji]

It's way too loud if I sleep with the windows open.

[ct0]

I'm starting to think that having a better night's rest while sleeping in a tent is not from the ground you sleep on, but the fresh air you've had all night.

[kccqzy]

My best sleep was on a camping trip when we decided that a tent wasn't necessary and we could just sleep outside watching the night sky.

(This is of course highly location dependent. Now that I think about it, I was probably taking a bit more risk at that time than what I tolerate now.)

[Cthulhu_]

It'll depend on the tent, I don't immediately associate tents with good ventilation.

[gumby]

A tent with poor ventilation rapidly becomes soggy.

[prmoustache]

you want to sleep below a tarp then, not in a tent.

[clairity]

> "although the effects of CO2 in cognition and energy levels are debatable"

it's really not debatable. the feeling of stuffiness is a function of many things, but environmentally, it's mostly temperature and humidity (we humans are hot and breathe out lots of humidity). there are no cognitive/energy effects until you get into the 10's of thousand of ppm, as the mechanism of action is competing out oxygen, not some intrinsic maladaption to CO₂, which is actually vital to life on earth. it's fashionable to hate on carbon right now (it's mediopolitical), and that's really all there is to it.

particulates, VOCs and chemical off-gassing, on the other hand, do have known mechanisms of harm, and that's something you should be more concerned about, but not yet alarmed. most of that pollution comes from cars and coal/gas power generation, so long-term, we should move toward more efficient habitation (e.g., denser cities, public transit) and cleaner power generation (including nuclear) if we really care about our collective health.

practically no one should be worried about CO₂ in their daily lives. it's thoroughly a red herring.

[sergioisidoro]

Yes they are debatable. There are cognitive performance tests that show statistically significant decline in many tasks above 1500ppm, especially on planning tasks. That's independently of the feeling of "stuffiness".

If these measurable declines have a sufficient impact on our lives and productivity is the debatable part.

Edit: here's one reference: "We also found effects of CO2 (a proxy for ventilation) on cognitive function. For every 500ppm increase, we saw response times 1.4-1.8% slower, and 2.1-2.4% lower throughput"

https://www.hsph.harvard.edu/healthybuildings/2021/09/09/imp...

[clairity]

if you look at the paper, you see no such conclusive evidence, but rather weak correlative assertions in noisy and complex environments. also notice the incentives and implicit bias of the involved. unbiased studies from the past several decades have so far shown cognitive effects require 10× that level of CO₂ to show any conclusive effects. even the pm2.5 effects attempt to make a short-term correlation, which is dubious at best. long-term pm2.5 effects are more conclusive, which is why we should be more concerned about them.

CO₂ is a fashionable concern but not scientifically supported. more importantly, it distracts from things we really should be concerned about as states and nations, like actual pollution and the alarming concentration of power and wealth.

[sergioisidoro]

See, they are debatable after all - we are debating them. There is data, there are some correlations that are statistically significant, and some raise even more questions — like why performance lowers at 1200ppm, but goes back up at higher concentrations in this article published on Nature in a very controlled environment - https://www.nature.com/articles/s41526-019-0071-6

I don't think this topic distracts from anything. I live in Finland, where indoor air quality is a big topic (mycotoxins and spores due to mold in old houses, burning wood in residential areas due to particulate emissions on cold days, construction codes, etc), while the country is making strides to become carbon neutral, and has one of the lowest economical inequality in the world.

But anyway, as I mentioned in the initial comment, the high CO2 just raised my attention to the bad ventilation of the house, and that includes ventilation of particulates from activities like cooking.

[clairity]

the CO₂ levels we see day-to-day (as long as you don't work in certain very specific industries) cannot have the effects that are fashionable to discuss. it's bullshit, an intentional disconcern for truth. bullshit by definition is distracting, as it literally takes attention away from truth-seeking and effective policy-making.

[fatuna]

Do you have any sources on this? I'm keen to know more, but googling results in either very dry researchpapers or ads on either co2 meters or air purifiers.

[clairity]

here's a USDA fact sheet summarizing the effects of CO₂ at different concentrations that's more easily digestible than an academic paper: https://www.fsis.usda.gov/sites/default/files/media_file/202...

[Rebelgecko]

There are a number of studies that have found that CO2 levels lower than the OSHA limit of 5,000 ppm can still cause issues like slight cognitive impairment and worse sleep (however there's also a few studies that have found no or minimal impact of levels below 5,000ppm)

[Cthulhu_]

It's a tradeoff, because good ventilation - ideally just open a window - also means heat is leaking out of the house, which costs money (and co2 emissions) to restore.

There's cyclic systems, but I live in a neighbourhood where some houses were equipped with it; on the proper setting, it was too loud so people turned it down, then people got sick from high CO2 levels in their house.

[BizarroLand]

There are ERV and HRV systems that will cycle fresh air in while exchanging the heat and moisture from the outgoing air to the incoming air.

It's a neat technology but the jury is still out on it.

Some people praise them, other people revile them, and they seem to be either too bulky or too cumbersome or too expensive or too inefficient for a DIY retrofit project.

[mypastself]

Not to hijack your thread, but I wonder if anyone here’s built their own Raspberry/Arduino CO2 monitor? Which (reliable) sensors did you use? Did you find it more affordable than purchasing a monitor, especially if you already had unused microcontrollers lying around the house?

[Lukas_Skywalker]

I built one based on the AirGradient DIY sensor [1]. It is open source, and you can order PCBs or build them yourself. It is also compatible with ESPHome.

It uses the "Senseair S8" CO2 sensor, which costs a bit (25-30$), but (according to AirGradient) has a very high quality.

[1]: https://www.airgradient.com/open-airgradient/instructions/di...

[Rebelgecko]

Seconding this recommendation. I was surprised how easy and cheap it was to order my own tweaked PCBs. Airgradient has also done a lot of testing to determine which components work well and what their different failure modes are.

Depending on how many you build at a time, you can source all the parts for maybe $40-$60. Assembly is straightforward as long as you're comfortable with through-hole soldering (and if not, this is a great chance to learn). The design is also modular enough that it's easy to skip on things like the thermometer or particulate matter sensor if you're so inclined.

[ProZsolt]

I'm currently developing my own monitor based on Sensirion SCD40(CO2/temperature/humidity) and Plantower PMS7003(PM2.5). The SCD40 is lot smaller than any NDIR sensor, but with the same accuracy[1].

My goal is to get a cheap (~$50) sensor in a small package that I can put in every room in my house. It will be modular so I skip the display and the PM2.5 sensor and it can be cheap as ~$25

[1]: https://www.airgradient.com/open-airgradient/blog/co2-sensor...

[GloriousKoji]

The microcontroller is the cheapest part! The good sensors that you want to use are in the $45 range. Look for "True" CO2 sensor that use some sort of optical technique to measure CO2. A lot of the really cheap CO2 monitors just measure VOC with some kind of metal element and approximate CO2. I like Sensirion SCD30 or SCD40.

[rcme]

I think the first step would be to buy a second monitor, ideally from a different manufacturer, and verify that your readings are actually correct. My experience is that cheap monitors are basically random.

[nicenewtemp84]

If your reader raises it's reading as you sit in a small room, and lowers when you open a window... It's probably not at risk of being random. Inaccurate maybe, but still sensing in the correct direction.

[lazide]

At least one (Big Clive pulled it apart I think?) had an Ethanol sensor in it.

[bsder]

Precisely this.

I haven't seen anybody take any of the cheap CO2 sensors and demonstrate that they are anywhere in the range of the readings of a lab grade CO2 sensor.

[beebeepka]

If possible, I recommend ventilation by creating a current by opening the front door and cycling every room (windos, balcony doors) of your apartment.

I do this every day regardless of the season. Works best during windy weather

[InCityDreams]

*watch out for slamming doors and windows :-) Took me ages to work out how best to perform such in my place, and yes - daily opening, even for 5 minutes - does seem to help (me). I also do it last thing at night. In the morning - a less stuffy apartment. On work days, I'll probably open for a few minutes before going to work, but definitely after getting home.

[oblak]

I use mostly chairs and pillows to prevent doors from slamming. What challenges did you meet at your place?

[sbaiddn]

That's why I'm not changing my very leaky and drafty windows - I don't want to live in a hermetically sealed Tupperware container.

Once I install an HRV system then I'll do the windows!

[Abekkus]

Or you could save $2k on materials & labor, and put in a filtered vent fan. You only need around 15CFM per resident.

Household HRVs & ERVs have suspiciously low heat efficiencies for their costs.

[BizarroLand]

85-95% isn't suspiciously low.

Where are you getting this information from?

[symlinkk]

Are you talking about a fan that simply blows outside air in? Wouldn’t that basically fight what the HVAC is doing? AFAIK the only real solution is an ERV / HRV, and they are extremely expensive (like $10k in my area)

[balfirevic]

No direct experience, but single-room HRV units look pretty cheap

https://www.amazon.co.uk/single-room-heat-recovery-ventilati...

[sbaiddn]

Does this "filtered vent fan" exchange air with the outside? If not, Im not interested.

[kccqzy]

This is of course also the reason why I don't like most office buildings. They don't have operable windows and rely on centrally managed HVAC. They sometimes have CO2 sensors but the system is too opaque for occupants to figure out at which level the mechanical ventilation starts.

[c3534l]

> , it shocked me and raised awareness to how poor my indoor ventilation is.

Do you want indoor circulation? Wouldn't that just mean your apartment loses heat/AC?

[GuB-42]

Yes, ventilation causes heat losses, but it is necessary.

There are ways around it though. The simplest is to not make sure ventilation goes where it needs to go. Modern buildings use mechanical ventilation to make sure every living space gets properly ventilated so one room doesn't get too much and another too little. Even better, some building use heat exchangers to heat/cool the incoming air with outgoing air, minimizing losses. Other techniques involve passing the fresh air underground, which, in a temperate climate gets you some free heating in the winter and free cooling in the summer.

Obviously, to limit heat losses, you want to reduce conduction and radiation too, which can be done without sacrificing ventilation.

[Cthulhu_]

The issue with heat exchangers and the like is noise on the one hand (can be suppressed of course), having it on the right setting (not too high if there's few people, not too low if there's many), and keeping the conduits clean (dust, moisture and heat is a great combo for some).

[kevincox]

You can use a heat exchanger to get "fresher" air while keeping the heat/cool inside. Although many places don't have this in place. It is probably mostly due to lack of awareness or concern than any technical reason.

[endisneigh]

Cost

[switchbak]

Letting your warm air go directly outside also has a cost.

Getting poor air quality for decades also has a cost.

Typing more than a one word reply is pretty cheap though.

[endisneigh]

you're right. things have tradeoffs. the point is that most barely have central AC with vents, let alone an HRV.

[switchbak]

Most homes don't have HRVs not only due to cost, but because homes didn't used to be tight enough to require them. We also didn't understand how important fresh air is.

Many homes didn't have AC because a) it was expensive, and b) you used to not need it as much.

And plenty of people can afford these things, cost is not the only consideration nor some magic word to dismiss the tech generally.

[swiftcoder]

In a heating/cooling system that has been specifically designed to improve ventilation, one can pull fun tricks like using the outgoing (stale) air to help heat/cool the incoming (fresh) air. Also in some places houses are built with enough thermal mass that the air within the building doesn't contain the majority of the heat therein.

In general there is likely some level of ventillation that will be worth taking on slightly increased heating/cooling costs.

[graeme]

Sure, but it's not nearly as costly as you'd think. We pay for all kinds of things. Including, compared to the past, much warmer air in the winter and much cooler air in the summer.

Growing up we used to put on sweaters, wear shorts, use fans, have the windows open in a car.

Changing our heating/cooling preferences to get rid of all that costs money. People don't mind.

But somehow, spending a small bit to breathe well and avoid indoor pollution/viruses is beyond the pale.

[aidenn0]

I do wonder how much of it is CO2 levels themselves and how much of it is high CO2 being a proxy for poor ventilation.

[za3faran]

Which monitor manufacturer are you using?

[sergioisidoro]

I bought mine from a construction material supply web store, and was looking for one of the cheaper ones. Its a Trotec. I wouldn't trust the absolute values so much, but i believe it's directionally correct.