I'd agree being in a room pumped with CO₂ would significantly deteriorate cognitive functions, but I have a feeling the studies are overblown WRT climate change.

Humans have high adaptability to increased CO₂ loads (see e.g. freedivers), but adaptation takes time. The studies usually deal with temporary CO₂ increases / O₂ decreases, often in way higher concentrations like 1-10%, whereas a couple percent atmospheric CO₂ would already burn us to a crisp (figuratively).

The studies are CO2 in the 500/1000/1500 and 600/1500/2500 ppm ranges, or 0.05-0.25 percent:

https://escholarship.org/content/qt6gm6t5zc/qt6gm6t5zc.pdf?t...

https://ehp.niehs.nih.gov/doi/10.1289/ehp.1510037

Thanks, seems I've missed a decimal. My questionable sources[1][2] mention concentrations up to 14000 ppm = 1.4% and seem to disagree whether going higher cognitive decline plateaus or it becomes harmful.

Seems there is merit for concern, though I stand by my claims of cognitive effects probably being more temporary than permanent.

[1] https://www.lesswrong.com/posts/DtQzYXBTwaWXbhCoS/stale-air-...

[2] https://www.advancedsciencenews.com/co2-on-the-brain-and-the...