ISS astronauts are routinely living in a 5000ppm environment. If the size of the effects of these studies were real, they’d be noticeable.

The most commonly cited study shows that 1400ppm cuts basic decision making ability by 25% and complex decision making ability by 50%. The study also shows a dose dependent response.

So how are people routinely operating at nearly 5 times that level for weeks at a time with no noticeable decline?

Results this large should by very easy to detect by simply measuring the CO2 levels at multiple SAT test taking sites and comparing scores.

Even without looking, an effect this large is the kind of thing that would jump out at the College Board or any other standardized test creator anytime they’re looking through their data to normalize scores or detect cheating.

Like I said I’m usually a scientific man but this is such a basic thing that anyone with any daily life experience would immediately recognize this 4000ppm (or whatever) as wrong.

Humans are also quite sensitive to noticing when a room is “stuffy”, so, yeah.

The problem with these casual discussions about CO2 levels is they don’t control for other factors. Opening a window definitely wakes you up, but is it the cold breeze or the CO2?

So yeah, my gut feeling was right. It’s probably good to not consider one negative study disproving a body of positive studies.

Here’s a good walkthrough of a meta study attempting to figure out what’s going on.

https://www.construction-physics.com/p/we-need-more-research...

This is why we do randomized, placebo controlled studies.

Saying “you can feel the mental fog clear” is likely a placebo effect.