
On whether changes in bedroom CO2 levels affect sleep quality - pizza
https://www.gwern.net/zeo/CO2
======
DocG
I was lucky to get my hands on 5 proper co2 sensors from university, while I
was teaching and working. So plenty of test places.

What I found:

-Just a couple of hours in a office, without ventilation spikes the co2 enough to make everyone dizzy and tired by the end of the day. Keeping eye on the meter and ventilating properly, increased everyones productivity and people werent so tired by the end of the day.

\- Classrooms, with 20-30 people are as bad. co2 rises really fast and makes
people dizzy. Most often ventilation is too low, as a cost saving measure.

-Closing bedroom door, sleeping alone made bedroom as bad by the morning than classroom or office.

-Main culprit seems to be our perfection with insulating and making rooms airtight. I do live in a cold climate, so having open vents or windows is not common half the year. It seems it has not been such a big issue before plastic windows or in older houses. I think it is getting worse with every new building.

~~~
AngryData
As someone who has built my fair share of houses and worked on many more over
the last 25 years, I have to agree that our ability to seal air better than
ever is causing problems, especially if you don't have forced air heating and
cooling running all the time. People just completely ignore or haven't ever
thought about room ventilation, positive or negative room pressures, and where
and how to ventilate to the outside. In older houses there was always air
leaks, small, but they let the house breath, especially if you had a central
fireplace and your house was at negative pressure. I have seen many people
purposefully over seal their house in ill conceived ways, to try and improve
insulation, but end up causing ventilation problems with mold being especially
common. Materials and vents that should let air pass through are commonly
replaced with impermeable plastics and sealing tapes, many times in
conjunction with a misunderstanding in expansion and contraction joints that
have small gaps.

~~~
marricks
And I recently remember hearing forced air is bad for air quality inside! Did
I hear wrong or is there something more to the story like “forced air brings
in outside air, so if your outside air is bad you’ll have trouble”?

~~~
Kadin
Most residential forced-air systems don't bring in air from outside
(intentionally at least). They recirculate the air in the building through the
heating/cooling unit (typically a combination updraft furnace with AC
evaporator sitting on top).

Modern systems (since late 80s, maybe?) have return air ducts so that you get
even heating even if interior doors (e.g. bedroom doors) are closed, but older
systems may only have one return vent per floor or even just a single one in
the house, and depend on gaps under doors and such for return air circulation.

Bigger commercial forced-air systems have had exterior air intakes and heat
exchanger systems for a while, but are pretty new for residential (I've never
seen one in the wild myself).

~~~
gregmac
Heat recovery ventilators [1] are reasonably common in Canada. Most (all?)
EnergyStar homes [2] have one, and they includes most if not all the houses
I've looked at (or friends have bought) in the past decade or so.

I lived in a house built around 1985 that had one, which was R-2000 [3], so
they're at least that old.

[1]
[https://en.m.wikipedia.org/wiki/Heat_recovery_ventilation](https://en.m.wikipedia.org/wiki/Heat_recovery_ventilation)

[2] [https://www.nrcan.gc.ca/energy/efficiency/housing/new-
homes/...](https://www.nrcan.gc.ca/energy/efficiency/housing/new-homes/5057)

[3]
[https://www.nrcan.gc.ca/energy/efficiency/homes/20575](https://www.nrcan.gc.ca/energy/efficiency/homes/20575)

~~~
gregmac
Oops, I meant houses that were _built_ in the last ~decade are mostly
EnergyStar.

------
bizzleDawg
I've worked on environmental sensing iot projects and have seen the cost of
co2 sensors. Almost all the cheap ones are VOC sensors which infer a co2 level
by assuming the VOC output is from humans (rather than paint for example).

Given the cost of the device I would be amazed if it wasn't a VOC based
sensor. The cheapest CO2 sensors I've seen are well over $250, even in bulk.
CO2 is quite innert, so it requires very precise and accurate components

~~~
dschuler
I got an NDIR CO2 sensor on AliExpress for $20. Do you think one of those
would just have low accuracy or be uncalibrated?

~~~
bizzleDawg
I suspect both! I should compare a $250 one with the $20 one

~~~
pstuart
That would be a worthy HN post.

~~~
illegalsmile
Is that something HN is interested in? I do work and research with remote
environmental monitoring stations and am always comparing sensors. Currently
doing a precipitation gauge intercomparison study.

~~~
pstuart
I can only speak for myself and what I've seen discussed here over the years
-- yes, it would be interesting. Why is better stuff is more expensive, how to
make the cheap stuff work closer to the better stuff, and interesting findings
from actually using them. Lessons learned are always interesting...

------
nkingsy
This is especially pronounced at high altitude, and when running a furnace in
the winter. I keep large black tents (4x4 ft or 2x4) in every bedroom in the
house, and grow kale, spinach, chard, peas, tomatoes, etc inside (with
handmade COB LED lights).

I don't have any sensors to get a real idea of the difference in CO2 it makes,
but it allows us to run the furnace less at night (heat from the lights), and
makes a noticeable difference in humidity ( very dry air here ).

Also, we get about 1-2 family meals / week of food at full capacity ( total
4x8 grow space and 800 watts of light running only at night ).

Not economical and takes a lot of maintenance, but it's a fun hobby from which
we all feel the benefits.

~~~
SketchySeaBeast
> but it allows us to run the furnace less at night (heat from the lights)

Dear God, what's your power bill? There's no way a LED lights heat is as
efficient as just using the furnace.

edit: I meant cheap, not efficient.

~~~
treis
Theres no difference in heating efficiency for any source. Heat is heat and it
doesn't really matter if it's generated from a heating element in a furnace or
an LED light. And with the light you're at least getting dual use out of it.

If they have a gas furnace it might be different but that would also depend on
how their electricity is generated.

~~~
lomereiter
Your statement is true if the electricity is generated locally, otherwise
there's a difference in energy losses depending on the carrier.

According to
[http://web.archive.org/web/20180822025250/https://portfoliom...](http://web.archive.org/web/20180822025250/https://portfoliomanager.energystar.gov/pdf/reference/Source%20Energy.pdf)
heating with grid electricity would require 2-3 times as much primary energy
as heating with water/oil/gas.

~~~
AstralStorm
Especially if you have central heating.

------
EngineerBetter
I really wish I'd read these comments and realised the experiment isn't
finished before scrolling up and down the article for five minutes trying to
find the conclusion.

~~~
privong
> I really wish I'd read these comments and realised the experiment isn't
> finished before scrolling up and down the article for five minutes trying to
> find the conclusion.

Gwern.net has useful heading information on each page. This particular one
says:

> modified: 13 Dec 2018; status: in progress;

Presumably the status tag will be modified to "draft" or "finished" once
conclusions are available. [https://www.gwern.net/About#confidence-
tags](https://www.gwern.net/About#confidence-tags)

------
buildbuildbuild
Gwern continues to be one of the most authentically curious and transparent
researchers around. I highly recommend perusing his essays. Thank you and keep
up the excellent output.

------
hawski
With every similar news I feel dumb. Because my parents and my grandparents
used to say same things. It was easy to dismiss all the advice as grumbling,
but I really should refresh air before sleeping, humidify air in heating
season, eat more vegetables... etc. etc.

~~~
newsgremlin
The problem is that parental figures previously based such general information
on gut feelings, personal anecdotes and old wives tales. A lot of what parents
say can be correct, but when there is a lack of information to fill the gaps
to a childs understandable inquisitiveness it's filled with ignorance or scorn
by the parents that are going through the motions who have no answer. It's an
interesting dynamic with the resources available for information to the
general public that it will be the children that can quash misconceptions
perpetuated by parents. We all, including future generations, will become
better parents for it.

~~~
hawski
I agree, but at the same time I feel that we are losing some of this common
folk knowledge. It is strange, because we are in this information age, however
it's full of noise. I'm not saying that it's bad to know how things are
extensively with scientific rigor. It's good, but we are sometimes throwing
the baby out with the bathwater.

My parents had limited vocabulary, but in a way they meant the same thing.
Stale air (a hopefully faithful translation from my language) can have many
meanings, but in context it means air with high CO2 concentration. I'm
wondering how much of this is also the disconnect caused by fast technological
progress and evolving language with it.

------
skuhl
Fire safety experts recommend that bedroom doors be closed at night:
[https://closeyourdoor.org/](https://closeyourdoor.org/)

~~~
invalidusernam3
The fire safety song on that site is hilarious:
[https://www.youtube.com/watch?v=Uu9ReCQgvv4](https://www.youtube.com/watch?v=Uu9ReCQgvv4)

~~~
chillwaves
That was way more entertaining than I expected. Shame they don't have many
views.

------
greenleaf2
There's one big problem with this entire idea of co2 levels affecting sleep
quality or humans in general:

Even though there are cognitive effects of CO2, most often the CO2 levels in
indoor rooms are simply a sign of low oxygen levels. In fact, there should be
an inverse relationship between CO2 and oxygen in rooms. So an experiments
would need to take this into account and supply pure oxygen to make up for the
oxygen that has been used up.

~~~
hannasanarion
It should be noted though, that the effects of low oxygen are already very
well known and well understood, thanks to decades of research funded by air
and space agencies.

It should therefore be pretty easy for CO2 researchers to control the outcomes
of their experiments against the known physiological effects of hypoxia, to
determine what effects are actually caused by CO2.

And aside from that, the dosages being discussed here are far, far lower than
would be a noticeable dent in the amount of oxygen in the atmosphere. 1000 ppm
CO2, the lower bound of observed cognitive effects, is 0.1% CO2, way less than
the point where hypoxia is known to cause problems. The atmosphere is 20.9%
oxygen at sea level and while I am not an expert in the math of partial
pressure, a decrease of atmospheric oxygen to 20.8% doesn't strike me as
sufficient to explain the observed effects. That's a 0.4% decrease in the
partial pressure of oxygen, or about the equivalent of a 300 foot increase in
altitude, or taking an elevator to the 20th floor of a building, nowhere near
enough increase in altitude to make you light-headed.

~~~
greenleaf2
The symptoms of slight sub-clinical hypoxia are in line with the observed
effects of people in high CO2 office rooms: headaches, concentration problems,
tiredness, etc.

In a closed small room, the oxygen is mostly used up after a couple of days.

One person in a small tightly closed room will lower the oxygen level
significantly, by 5-10% (consumption is around 20 cubic feet, and a small room
has about 200 cubic feet oxygen in volume in total)

CO2 and oxygen work in tandem in the human body, and studies in the medical
field have shown that an increase in carbon dioxide increases breathing rate,
breathing volume, heart rate and metabolic rate.

The result is an increased need for oxygen, which will not be met in a closed
room.

Thus I speculate that an increase in CO2 with an accompanying increase in
oxygen (or at least a stable flow) will mostly negate the observed symptoms.

My preliminary working theory would be that the previously observed effects
from high CO2 in rooms (office rooms for example) are due to the interaction
of both high CO2 and low O2.

------
marijnz
Previous company I worked for had dashboards and Slack integration for the CO2
levels on all floors. There's a blogpost on how it was done (Raspberry PI's,
CO2 sensors and open-source python script): [https://blog.wooga.com/woogas-
office-weather-wow-67e24a5338](https://blog.wooga.com/woogas-office-weather-
wow-67e24a5338)

------
freetime2
In Japan, the building code requires every room to have an air vent [1].
Initially I was skeptical of them and was looking to close them to save on
heating costs in the winter. But after doing a little research, I decided they
are probably best left open to reduce condensation and mold growth.

Now I'm curious how effective they are at keeping down CO2 levels at night. I
would like to try this experiment in my house.

[1] [https://resources.realestate.co.jp/living/japanese-
apartment...](https://resources.realestate.co.jp/living/japanese-apartment-
air-vents-use/)

~~~
rikkus
There are regulations[1] in the UK too.

We've had new UPVC windows installed over the past few years and they've all
got hidden 'trickle' vents.

[1] [https://www.gov.uk/government/publications/ventilation-
appro...](https://www.gov.uk/government/publications/ventilation-approved-
document-f)

------
manmal
FWIW, I have almost no dream recall, and am not as rested, when the window is
sealed shut. We are four humans and two cats (usually) in a small-ish bedroom,
creating a lot of co2. There is built-in ventilation in each room, but
performance starts declining 2 weeks after every filter change (which cost
€20). So I swap the filter only once every 1-2 months, and instead open the
window ever so slightly (moving the lever just a bit towards open position,
weakening the seal). Voila, perfect dream recall and much better rested the
day after.

~~~
sinuhe69
I live in a tropical country and I always prefer to sleep with open Windows.
The only problem is the noise. I believe noise affects the sleep quality as
much as well. Earplugs might be a solution but I don’t know any good brand
which are comfortable enough for long time carrying.

~~~
manmal
It seems there will soon be a mass market solution:
[https://www.haaretz.com/israel-news/business/sick-of-the-
noi...](https://www.haaretz.com/israel-news/business/sick-of-the-noise-this-
startup-has-developed-a-quiet-bubble-1.6336531)

------
co2_throwaway
This might be completely unrelated, but let's give it a shot:

I've noticed that sometimes after spending extended periods of time (in the
magnitude of hours) in very close proximity with a significant other (e.g.
cuddling, kissing, etc.), I feel groggy, dizzy, and have brain fog/difficulty
focusing.

Could this be related to CO2 levels? I've been feeling it today and was
wondering if it is hormone related, but CO2 could be an interesting
explanation as well - I have noticed my breathing tends to slow down during
these times as well.

I've never heard anyone else describe this so if you have any similar
experiences, please share so I don't feel so alone with this.

~~~
jdpigeon
There's a lot going on physiologically when you're getting intimate (e.g.
oxytocin, testosterone), so it's hard to tell. However, I've noticed the same
thing, and I'll also add a loss of appetite.

~~~
co2_throwaway
Glad someone can relate, but sorry you have to deal with it as well.

What are your thoughts on seeing an endocrinologist about this? In addition to
oxytocin, testosterone, etc., I was also wondering if it might be related to
prolactin levels.

I also just read some people talk about similar symptoms here but no clear
answers: [https://patient.info/forums/discuss/partner-becomes-ill-
afte...](https://patient.info/forums/discuss/partner-becomes-ill-after-
kissing-intimacy-please-help-73181)

------
yoodenvranx
Is it just coincidence that Tom Scott uploaded a video about CO2 and its
influences at almost the exact time the gwerns link was submitted?

[https://youtu.be/1Nh_vxpycEA](https://youtu.be/1Nh_vxpycEA)

~~~
philippnagel
Wasn't there a recent discussion on HN on the Baader-Meinhof Phenomenon?

~~~
tinus_hn
It appears it has become pretty fashionable to mention it, it’s probably the
next ‘skeuomorphic’.

------
jere
I'm eager to hear the results. I recently got an Awair 2.0 after seeing this
talk by DHH:
[https://www.youtube.com/watch?v=MRqh8oLY7Ik](https://www.youtube.com/watch?v=MRqh8oLY7Ik)

It quickly confirmed that, without turning my thermostat fan to "ON", my
bedroom CO2 jumps from about 1000 ppm to 2000 ppm within a couple hours of us
going to sleep.

In the fall, my wife and I started waking up in the middle of the night
feeling like we couldn't breathe. What I figured out is that the neither the
heat nor cooling was running because the weather was pretty much perfect. We
have to keep the door closed because our cat will swat at us in the middle of
the night otherwise. I figured there would naturally be enough of a draft to
not make this a concern and it's a fairly large connected master
bedroom/bathroom with high ceilings to hold a lot of air, but I guess that
isn't enough. So that's when I learned about the "fan" function on my
thermostat.... never had a need for it in my life.

Now I just need to figure out how to get lower than 1000 ppm, which is already
a hit against cognitive function. Our house has no screens currently and even
if we install some, it's not like I want to have windows open in the middle of
winter. I've heard house plants don't have a huge effect, but I'm willing to
try.

~~~
colek42
Install an air exchanger. Panasonic makes some that are reasonably priced.

~~~
halbritt
They're called energy recovery ventilators or ERVs. The Panasonic units are
most well-regarded.

------
simulate
Scott Alexander (slatestarcodex) provided a meta-study and also described how
reducing CO2 in his cottage reduced headaches, fatigue, and poor sleep:
[https://slatestarcodex.com/2018/08/23/carbon-dioxide-an-
open...](https://slatestarcodex.com/2018/08/23/carbon-dioxide-an-open-door-
policy/)

After reading this, I got a Netatmo CO2 monitor like Scott and Gwern. I found
that CO2 peaked in my bedroom at around 1500 PPM at 6 AM with the door closed
and that I could keep it under 500 PPM with the door open or a window open.

Scott Alexander also suggests getting around 10 succulents, if you don't want
to open a door or a window.

Edit: Scott Alexander also published these survey results from other people
who experimented with reducing CO2 in their homes:
[https://slatestarcodex.com/2018/10/04/nighttime-
ventilation-...](https://slatestarcodex.com/2018/10/04/nighttime-ventilation-
survey-results/)

~~~
wishinghand
How big should these 10 succulents be?

------
Someone
_”But if one room can mix with and increase the Netatmo’s room all the way up
to 1934PPM, what must the original concentration have been like?”_

Why not move the weather station to the bedroom for a couple of nights? (And
make sure the sensor is at nose/mouth height, preferably close to it. CO2 is
heavier than air, so concentrations may be higher closer to the floor in a
closed room with little movement)

I would also do a back-of-the-envelope computation along the lines of
[https://www.globe.gov/explore-science/scientists-
blog/archiv...](https://www.globe.gov/explore-science/scientists-
blog/archived-posts/sciblog/2008/08/11/release-of-carbon-dioxide-by-
individual-humans/comment-page-1/index.html) or [https://ac.els-
cdn.com/S1877705813007558/1-s2.0-S18777058130...](https://ac.els-
cdn.com/S1877705813007558/1-s2.0-S1877705813007558-main.pdf?_tid=c67910cb-94a1-4250-a050-984934b01197&acdnat=1548097951_5b5b22f418db1b47241559338fe2bb24),
to verify the numbers the weather station produces.

And the lesson of all this seems to be: get a large bedroom and leave the door
open (both easier for the well-off, so get rich parents!)

~~~
larrik
_" Why not move the weather station to the bedroom for a couple of nights?"_

which he did, not too far further into the article?

~~~
Someone
Oops. I thought I skimmed the text well enough to detect that, but apparently
was looking too much for the graph “CO2 concentration over time during the
night” that to me, seemed obvious as the thing that had to be there.

------
alvern
For the hackers out there, you can record CO2 with a K33 sensor. The [0] Livpi
uses this chip.

EDIT: it appears the Livpi uses a K30 chip. The K33 [1] is the version sold on
industrial sites.

[0] [http://www.livpi.com/](http://www.livpi.com/) [1]
[https://www.co2meter.com/products/k-33-icb-
co2-sensor](https://www.co2meter.com/products/k-33-icb-co2-sensor)

------
tux1968
Went looking for devices for the bedroom, but ran into an article about plants
that might help in that setting:

[https://thewgnews.com/planting-hope-air-cleaning-house-
plant...](https://thewgnews.com/planting-hope-air-cleaning-house-plants/)

~~~
graeme
Those scrub the air of pollutants. No way they lower co2 sufficiently though.
Plants reduce co2 by growing. Which they do....slowly. By contrast a human
will spike the air in a room quickly by breathing.

~~~
tux1968
That's interesting, I was just linking the article because it was talking
specifically about co2 and NASA recommendations. In fairness, it didn't give
any hard numbers on what to expect.

~~~
graeme
I think the author of the piece just made a poor inference. Air cleaning isn't
necessarily the same as lowering co2.

That said, seems there are some succulents that do most of their co2 intake at
night. Those would work best for co2. But you would need....at least 30-40 of
them.

Opening a window, by contrast, works extremely well, and quickly. However,
this requires non-polluted outside air. Else you're exchanging lower co2 for
pollutants.

[https://gerrieswart.com/2018/09/06/using-plants-to-
improve-y...](https://gerrieswart.com/2018/09/06/using-plants-to-improve-your-
sleep/)

~~~
tux1968
Opening a window is just a bit too expensive in the -20 degree weather we're
getting around here right now :-)

~~~
graeme
I don't think a tiny crack makes that much difference. I also live in a -20
area. Also the colder it is, the easier venting happens, so a small crack has
the same effect as having the window open much more in summer.

I can't remember the total, but I recall seeing a calculation about this and
it didn't amount to very much energy, especially if the bedroom heat isn't on
super high.

Anecdotal, but I've heard the Germans often tend to keep a window open a bit
year round, and I know my grandma did even in winter. She was pretty frugal
too.

------
efficax
I read somewhere that in Germany it is (or was) traditional to "luften" the
rooms of a house every day by opening the windows for a while to let fresh air
in (even in the winter). After hearing about this I started doing it myself,
and I feel like it's improved the experience of working from home. Even when
the subzero temps descend on my city in the next few days, I'll open a few
windows for a while just to make sure the air stays fresh.

------
maxk42
Just wanted to write to say after reading this article I went out and bought a
CO2 meter. Levels in my house were high enough to effect drowsiness and
trouble concentrating. (> 1100ppm, even with the window cracked) Subsequently
decided to leave my sliding glass door open all day, allowing levels to drop
to around 550ppm. Haven't felt this alert and active in ages. What the hell
have I been doing to myself?

~~~
elektor
What CO2 meter did you buy?

------
lmilcin
Couple of months ago I changed jobs and have moved to a new city with my
family. Due to unusual working hours I keep separate bed in my tiny office (10
square meters or roughly 100 square feet).

As soon as I have moved I have started having trouble with my work which I
initially assumed was due to me being overworked and tired with the entire
hoopla around the change.

Only after about 3 months I have finally figured out to keep the room door
open at night to allow the air to circulate. It immediately helped. My office
in my previous flat was not tight and the air always flowed even when the
doors were closed. The new one is completely sealed when the doors are closed.

------
tvladeck
i can't wait for the final results of this analysis.

for a long time i've wondered why i was so sleepy. i often work out of my
apartment (a new building), and NYC being NYC, my windows and doors are often
closed to allow for air conditioning.

i bought an awair sensor, and when i plugged it in, i was getting readings of
1000-1500ppm on CO2. immediately started ventilating the apartment, outside
weather be damned. impossible to tell, but i feel more awake and healthier in
general now. i also make it a point to get outside more and work more from my
office (which is very big and airy and lightly attended).

~~~
toufiqbarhamov
I just want to say that while suggestive, correlation and causation yadda
yadda. If you find that you’re tired all of the time, prone to falling asleep
whenever you sit down somewhere, and _especially_ if you snore or often wake
up with a headache...Get A Sleep Study! You may have sleep apnea, which is
quite common and easy to treat. These days you can get a take-home kit under
most insurance, and if you need the full clinical study they’ll go from there.

It’s all totally painless, and the change proper treatment makes if you need
it can’t be overstated. Sleep apnea could also conceivably make you more
sensitive to nocturnal hypercapnia.

------
throwwayy136
I am already baffled that a major Dutch periodical (Elsevier magazine) fails
at typesetting the "2" in "CO2" in subscript, but gwern? (Et tu, gwern?)

------
harshulpandav
I live in a tiny apartment that probably only circulates the air within the
apartment itself. The system sucks air from one spot and throws it out from
the vents at all places.

To force fresh air to come inside I keep the door of my room open and open the
window by 3 inches. Turn on the HVAC. Thus all the air from my room is sucked
and because of the pressure difference fresh air gushes in. This works for me
pretty well.

------
erikb
Have I missed it or are there no results in the article? First he has a long
intro, which is nice. Then he goes way over board explaining his data and
code. Then he talks about his mattress. If you've seen results can you point
them out to me? Thanks.

------
z3t4
I measured CO2 levels in my bedroom and it where highest just before sleep
(around 1000ppm), then wen't down during sleep. The article got some very high
readings. Either they're doing "exercise" or the room has bad ventilation.

------
baxtr
Related side question: does anyone know when and if we would see CO2 levels in
the atmosphere of around 2000-3000 ppm because of all the fossil fuels we burn
(which I understand is a level that is not optimal for us)? I’m asking for a
friend...

~~~
Shank
Not any time soon, as far as I'm aware. According to [0] a fancy article from
Business Insider, the rate of increase is 2ppm/yr, on average.

But many studies suggest cognitive effects of CO2 levels as low as 1,000ppm.
See:
[https://ehp.niehs.nih.gov/doi/10.1289/ehp.1510037](https://ehp.niehs.nih.gov/doi/10.1289/ehp.1510037)

[0]: [https://www.businessinsider.com/carbon-dioxide-record-
human-...](https://www.businessinsider.com/carbon-dioxide-record-human-health-
effects-2018-5)

~~~
baxtr
Thanks! So 2ppm/year gives us another 300 yrs to top 1000 ppm. I guess we’re
safe for now! Rock on

~~~
Retric
Your local air has higher CO2 than the environment even today it can reach
1000 ppm with poor ventilation. So, it's likely to be an increasing issue long
before we hit 1000 ppm outside.

------
aresant
In modern houses the solution to this is a “whole house air exchanger” which
acts to cycle on low power the airflow in/out of house. You can also get these
for single rooms and equipped with a heat recovery component.

~~~
Tharkun
I was under the impression that heat recovery ventilators weren't worth their
cost. They're a lot more expensive to buy, and a hell of a lot more expensive
to install (complicated ducting etc). Has that changed in recent years?

------
dzhiurgis
I really wish smartphones would start monitoring CO2 (together with CO, UVA,
UVB, humidity and probably some other interesting metrics).

Some of these sensors cost nearly nothing at scale, but would save thousands
if not millions of lives.

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nwah1
CO2 negatively affects cognitive performance on tests

[https://ehp.niehs.nih.gov/doi/10.1289/ehp.1510037](https://ehp.niehs.nih.gov/doi/10.1289/ehp.1510037)

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fourier_mode
Slightly related[0]: Explains the effect of CO2 concentration on cognition.

[0]
[https://www.youtube.com/watch?v=1Nh_vxpycEA](https://www.youtube.com/watch?v=1Nh_vxpycEA)

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swixmix
It doesn't appear that CO2 was the only variable in this experiment. Usually
when people cause CO2 level to rise they also cause the O2 level to fall.
Also, increasing oxygen will wake you up.

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gamma-male
In my bedroom I can feel the morning dew in my lungs. I've been wondering if
it is bad. Could be lead as well, it's an old house, but I don't think I would
be able to feel it.

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amelius
Any implications at a bigger scale, i.e. considering rising global CO2 values?

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maxxxxx
No, the concentrations are totally different.

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norswap
It's a cool experiment, but why post this — there aren't any conclusions yet!

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fromthestart
This has all the markings of a pseudoscientific fad.

1\. Abundance of flimsy anecdotal evidence

2\. Mostly subjective measures of outcome (I feel smarter and refreshed!)

3\. Seemingly plausible, but totally unverified scientific reasoning

I'm not holding my breath yet.

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diminoten
Self experiments like these are a great re-enforcement of how insanely hard it
is to do accurate, reproducible science. This submission tells us absolutely
nothing due to the lack of rigor applied.

SO many potential confounding variables, there is zero value in what is being
done here.

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tgb
Here's a Nature opinion piece arguing in favor of N=1 studies:
[https://www.nature.com/news/personalized-medicine-time-
for-o...](https://www.nature.com/news/personalized-medicine-time-for-one-
person-trials-1.17411)

And another more recent one
[https://www.nature.com/articles/d41586-018-07535-2](https://www.nature.com/articles/d41586-018-07535-2)

~~~
diminoten
The n=1 isn't the problem, it's the environment. "Some guy's room" is hardly a
lab, and _then_ , when there is so much that can go wrong, such as in this
study, n=1 is terrible.

This is terrible pseudoscience and not worth anyone's time.

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zmix
So, TRUE or FALSE?

