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).
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?
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).
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.
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.
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.
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.
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.
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).
> 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...
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)
>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.
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.
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?
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.
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.
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!
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!
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(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::)
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.
Carbon monoxide comes from vehicle exhaust, so the levels are still lower outside cities and off high-traffic roads. I'd rather recirculate my "stored up" clean air vs. pull in CO from the line of cars stopped ahead of me. I just involves being aware of the surroundings.
Ideally a controller would monitor the outside CO/PM and inside CO2 to control the recirculate door.
> Location is generally less important than wind direction here
My experience (and my nose) strongly disagrees with this assertion. YMMV.
The urban-vs-rural divide in my area is shockingly detectable just by the smell of combustion byproducts alone.
> you aren’t tracking [wind direction]
Who says I'm not? Tall flagpoles make for nice, ubiquitous windsocks. I wouldn't use it to land a plane, but for this purpose it works just fine.
And yes, it's absolutely a hard problem. Just look at all the ink I've spilled...
The human nose (especially mine) is still a remarkable chemical sensor, with only a few blind spots. In practice the major blind spots, namely CO, correlate well with detectable combustion byproducts. I appreciate your concern, but you worry for no good reason!
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I'll share one final trick, which should be pretty obvious: avoid sucking in the packet of air a bunch of cars (or one diesel truck) just accelerated through. In practice, usually this means turning on recirculate when stopping behind a line of cars, and then waiting to turn off recirculate until a short distance after going through the light.
Just to preempt the seemingly-inevitable negativity reflex: if you don't believe such hyper-local variations in pollution make a big difference, I guess you've never cycled before. ;)
Urban/suburban areas provide a different variety of smells which is easy to confuse with overall toxicity levels. Chemical sensors will sometimes line up with your expectations and other times be very different.
Trust me, I know what vehicle exhaust smells like. ;)
Living outside the city, I'm not constantly fatigued to its odors. So that's not a factor.
But more to my original point, it disproves the "wind > location" idea (in my geography), since odor acts as a tracer for packets of air coming from the city.
I wish I could calm your anxiety, but on the bright side I am truly touched by your outpouring of concern for my respiratory well-being! Thank you, kind stranger.
You seem to misunderstand, Olfactory fatigue is very fast. When people fart for example the perception of smell goes away vastly sooner than the actual smell.
If you’re trying to judge air concentrations based on how intense the smell, it simply doesn’t work.
I'm judging the presence of air pollutants. If I can smell it (ie above the lower detection limit), then I know I'm being exposed.
The converse is not necessarily true of course, but I can do this without hundreds of dollars in sensors. "Do what you can, where you are, with what you've got."
To account for sub-detectable pollution levels, I generally give myself a little extra buffer room. If I observe that detectable pollution odors begin at a certain point, I'll engage recirculate a half-mile before.
Generally nowadays I successfully avoid any detectable pollution/proxy odors, using the sort of preemptive planning I've described. You should try it!
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TL;DR this whole thread: recirculate gives better air quality, just flush CO2 periodically, ideally when in relatively cleaner air
Moving from constant levels of pollution to intermittent levels of population you notice ever stronger smells even as things improve. The reverse is also true, going from intermittent smells to constant toxicity it seems like things are improving.
This is the case because you most easily notice rapid changes not overall levels.
And again, both articles ignore the possibility of having better filters.
Not really. What I currently do prevents any health flare-ups, so it's working for me.
I might be effected by sub-detectable levels of pollution. I definitely would be effected by detectable levels of pollution. So I know I'm better off, which makes me happy.
I do not confuse this with perfection, but this level of cost/benefit tradeoff is "good enough" for me. Some of these tricks might be helpful for other people too!
> Moving from constant levels of pollution to intermittent levels of [pollution]
This is not my situation.
> And again, both articles ignore the possibility of having better filters.
I didn't write the articles, I just cited them to support the fact that recirculate results in lower pollution levels in cars.
I, in my life, very much do not ignore air filters. :)
> recirculating results in lower <particulate> pollution < and higher non particulate pollution>
Again, assuming inadequate filters, better filters invalidate their results.
> sub detectable
This is very much detectable, we just ignore it. Come back from a long trip to a remote enough area and it’s shocking how much everything smells, even small country roads briefly stink of pollution.
But, I think the dead horse has been beaten enough at this point.
> This is very much detectable, we just ignore it.
Nevertheless, sub-detectable levels we can ignore are lower than sub-detectable levels we can't ignore. So I'm still better off than I would be otherwise. How is this so hard to understand?
You're letting perfect be the enemy of good. This is the critical point you've been ignoring this whole time. All the horse beating could have been avoided! ;)
> recirculating results in lower <particulate> pollution < and higher non particulate pollution>
Your "non particulate pollution" is just exhaled CO2. This is covered when I mention periodic flush of air. For obvious reasons, the editor inside me didn't feel the need to mention CO2 twice (especially not via muddy language like "non particulate pollution") in what is supposed to be a TLDR.
You should clarify, not obfuscate. Listening to your advice, it's confusing whether to prefer having recirculate on or off. You failed to clearly convey the most critical piece of information.
> better filters invalidate their results
"Better" is vague, so this advice is un-actionable.
Without citation I can only assume you just mean bioweapon defense mode, correct?
> There isn’t a level of smell you can’t quickly ignore.
Not a fixed level, of course! But at any given instant, the level you can ignore is lower than the one you can't. Hence I'm still better off doing this, a fact which apparently you can't stand for some weird reason...
You're also going to gather data over time, which will tend to smooth out any such day-to-day variations.
This is how you can reduce (not eliminate) pollution exposure without paying for expensive non-nose sensors. This is true whether you Believe It Or Not™.
>No, it’s carbon monoxide, NOx, SOx compounds etc.
Citation desperately needed. I showed you mine, you show me yours!
What conceivable mechanism could concentrate these traffic pollutants higher than the outside concentration? Are you running a pump that's somehow fighting entropy to push these outside traffic pollutants (against the alleged concentration gradient) into your car??
Usually it helps if your claim doesn't violate the laws of thermodynamics. :D
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edit: I'll throw you a bone to save time. Literally the only way to achieve this outcome without violating physics is to intentionally reverse my recommendation: try to suck in only the most polluted urban air (intake the concentrated plume from a line of cars accelerating, behind a garbage truck or schoolbus, etc), and then switch to recirculate to save up that highly polluted air and breathe it for as long as possible.
So...... don't do that! If you're studying IAQ in cars, you need to control for that.
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?
There should be very low levels of CO (at least from your car) in the engine bay, since exhaust is vented out the back of the car, and your engine shouldn't be leaking exhaust gases in other places. You might have some CO there from the cars in front of you, though.
The air intake in the grille is only for the engine’s use. The fresh air intake is not in the engine bay, it’s typically at the base of the windshield.
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.
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.
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.
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.
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.
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.
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.
> "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.
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"
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.
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.
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.
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.
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)
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.
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.
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?
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.
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.
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
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.
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.
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.
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.
*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.
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)
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.
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.
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).
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.
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.
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.
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.
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.
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