# There may be low hanging fruit for a weak nootropic

**The problem**
---------------

You are routinely exposed to CO2 concentrations an order of magnitude higher than your ancestors. You are almost constantly exposed to concentrations two times higher. Part of this is due to the baseline increase in atmospheric CO2 from fossil fuel use, but much more of it is due to spending a lot of time in poorly ventilated indoor environments. These elevated levels are associated with a decline in cognitive performance in a variety of studies. I had first heard all of this years ago when I came across [this video](https://youtu.be/1Nh_vxpycEA?si=Yh2HZHGa1utjFMk4) which is fun to watch but, as I’ll argue, presents a one sided view of the issue[^zyntv0omjh].

This level of exposure is probably fine for both short and long term effects but essentially everyone alive today has not experienced pre industrial levels of CO2 which might be making everyone very slightly dumber. I don’t think this is super likely and if it happening it is a small effect. But, it is also the kind of thing I would like to be ambiently aware of and I am kind of disappointed in the lack of clarity in the academic literature. Some studies claim extremely deleterious effects from moderate increases in CO2[^31rwh8bns7a], some claim essentially none even with 4000ppm[^830oci2c9cb], ten times the atmospheric concentration.

![](https://39669.cdn.cke-cs.com/rQvD3VnunXZu34m86e5f/images/d89459880180be4fe3c04a3decf861c2b647d090bfbbb9e5.png)

![](https://39669.cdn.cke-cs.com/rQvD3VnunXZu34m86e5f/images/f252e244ed61f2cdb97472854f42a447650fe05a73cff75b.png)

The main graphs from the above studies show ridiculously different results. These were intentionally chosen to contrast and make the point.

A lot of the standard criticisms of this kind of thing apply, underpowered studies, methodological flaws for measuring cognitive performance or controlling CO2 concentration, unrepresentative populations[^5ckfzhz4fim], and p-hacking via tons of different metrics for cognitive performance. All of this makes even meta analysis a little unclear. This [blog post](https://www.construction-physics.com/p/we-need-more-research-on-how-co2) covers a [meta analysis](https://pubmed.ncbi.nlm.nih.gov/32557862/) pretty well and the conclusion was that there is a statistically significant decreases in performance on a Strategic Management Simulation (SMS) but that was comparing <1500ppm to <3000ppm which is a really wide range and kind of arbitrary. However, nobody has done the experiment I think would be most interesting. That being a trial where subjects are given custom mixes with 0ppm, 400ppm, and 800+ppm. This would answer not only if people are losing ability from poorly ventilated space but also if we are missing out on some brain power if we had no CO2 in the air we breathe in. Again, the effect size is probably pretty small but one of the studies was looking at a drop in productivity of 1.4% and concluding that that level of productivity loss justified better ventilation. Imagine if the whole world is missing out on that from poor ventilation. Imagine if the whole world is missing out on that because we are at 400 instead of 0. Again, not likely but the kind of thing that would have big (cumulative) downsides if true.

I tried looking at the physiological effects of CO2 and did not do as deep a dive as I would have liked but [this paper](https://pmc.ncbi.nlm.nih.gov/articles/PMC3139085/pdf/tjp0589-3039.pdf) claims that there is a dose response relationship between cerebral blood flow and CO2 concentration (in the blood) and that it really levels out beneath ~normal physiological levels. I take this to mean that there would be a small, but measurable, physiological response if I could remove all the CO2 from my blood, which they did by hyperventilating.

Along the way I started looking at physiological effects of O2 availability and, well, I have some words about a [particular article](https://journals.physiology.org/doi/epdf/10.1152/ajpregu.00165.2017) I found. Look at this graph:

![](https://39669.cdn.cke-cs.com/rQvD3VnunXZu34m86e5f/images/e42e6122548f60d7cc7a28c6018d42a05d6c3bfa9a33e4f5.png)

It looks like there is some homeostasis going on where your cerebral blood flow can go down because there is more oxygen in the blood (%CaO2) giving you the same amount delivered (%CDO2). The only issue is that they said “When not reported, DO2 was estimated as the product of blood ﬂow and CaO2.” When I read that I felt like I was losing my mind. Doesn’t that defeat the whole purpose of looking at multiple studies? If you just assume that the effect is given by some relation, fill in data based on that assumption, and average out with real data of course you’re going to get something like the relation you put in. As one of the many not doctors in the world, maybe I should stay in my lane but this does strike me as a bit circular. I am not convinced that an increase in atmospheric O2 does not lead to an increase in the O2 delivered to the brain. Especially because decreases in O2 partial pressure are definitely related to decreases in O2 (and cognition) in the brain and it would be kind of weird if the curve was just totally flat after normal atmospheric levels[^j47s9t828g].

I also found one very optimistic group claiming that breathing 100% O2 could increase cognitive performance in two [main](https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.1175649/full) [papers](https://www.sciencedirect.com/science/article/abs/pii/S0166432823003765?via%3Dihub). They are both recent and from a small university so it makes sense that this didn’t get a ton off attention but that doesn’t really make me less skeptical that it’s just that easy. The first paper claimed 30% increase in motor learning and I would expect that effect size to decrease significantly upon replication.

All this leaves four main possibilities the way I see it:

1.  No effect, everything is business as usual for usual O2/CO2 ranges
2.  CO2 decreases cognitive ability with a dose response relationship even at low doses
3.  O2 enriched air can have significant gains that basically nobody has captured
4.  VOCs[^28uh8my8hrw] have bad effects and ventilation reduces their concentration and that is what confuses the hell out of all these studies

**My solution**
---------------

Well, I don’t have the resources to do a randomized control trial. But, I do have the ability to make a CO2 scrubber and feed the treated air into a facemask so I can breathe it. If I do this, I’m not buying the parts until I confirm nobody leaves a comment just demolishing the central thesis, I would probably wait until spring as opening my windows seems like a big important step to having low ambient CO2[^6w9lkdzuarj] but would be pretty miserable for me while there’s still snow outside.

This is a chance to talk about some cool applications of chemistry. The idea is that CO2 can react with NaOH to form only aqueous products, removing the CO2 from the air. These can then react with Ca(OH)2 to yield a solid precipitate which can be heated to release the CO2 and reform the Ca(OH)2. This is, apparently, all pretty common for controlling the pH of fish tanks so that’s convenient and cheap.

I’ve already been trying to track my productivity along with a few interventions so I plan to just roll this in with that. This won’t be a blinded trial but I am happy to take a placebo win if it increases my productivity and if it doesn’t do anything measurable I’m really not interested in it.

As for oxygen enrichment, you can buy oxygen concentrators, nitrogen filters that people use for making liquid nitrogen instead of liquid air, medical grade oxygen, oxygen for other purposes, or make it with electrolysis. All of these strike me as being somewhat dangerous or quite expensive to do for long periods of time. [Someone else on LessWrong wanted oxygen](https://www.lesswrong.com/posts/3CKvhF8DBnYd7anFx/out-paternalizing-the-government-getting-oxygen-for-my-baby) (for a much better and less selfish reason) and got some for divers/pilots. I would do that, but again, expensive.

With any luck, I will have a case study done on myself at some point and can update everyone with the results.

[^zyntv0omjh]: I don’t want to be harsh, the video is only a few minutes long, is made by a climate activist who already has some strong beliefs on CO2, and he did put his own mind on the line as a test case to make a point which I applaud. Given those reasons and that he seemed to have quite negative effects from the CO2 himself I think it is quite fair that he didn’t have a detailed counterargument presented. 

[^31rwh8bns7a]: https://pmc.ncbi.nlm.nih.gov/articles/PMC4892924/pdf/ehp.1510037.pdf 

[^830oci2c9cb]: https://www.nature.com/articles/s41526-019-0071-6 

[^5ckfzhz4fim]: The group used “astronaut-like subjects” which is fine but I don’t know if that generalizes to most other people. 

[^j47s9t828g]: Not hugely surprising though, we did evolve to use the atmospheric level so I wouldn’t be shocked if it was flat, just that this study didn’t convince me that it was flat. 

[^28uh8my8hrw]: I realized I did not talk about VOCs, volatile organic compounds, at all. They are just a wide variety of chemicals that permeate the modern world and are probably bad in ways we aren’t certain of. 

[^6w9lkdzuarj]: As an aside, I would not be shocked if poor ventilation during the winter was a contributing factor to seasonal affective disorder but I don’t have that and did not look into anyone checking if it is true.