[PragmaticPulp]

CO2 concentrations are an ongoing topic of debate. There are studies that show no measurable cognitive changes up to CO2 concentrations in the thousands of PPM, while other studies seem to show cognitive changes at much lower amounts.

I tend to think that people with CO2 sensors tend to over-focus on CO2, when really what they’re feeling is the general stuffiness of a room. CO2 isn’t the only thing that accumulates in the air in an enclosed space, but once you have a CO2 meter in hand you might think it’s the only thing that matters.

That said, CO2 levels can be used to somewhat estimate the amount of rebreathing going on in a space. That is, the amount of air that you breathe in that has been exhaled by someone else. It’s not entirely pleasant, which can explain why people feel like they don’t like high CO2 levels

[paulcole]

I wondered this too. Like yeah you’re going to be cognitively drained after being in a crowded closed meeting room for a long time. Is it because you were talking and working or because of the CO2.

[dredmorbius]

If the sense lifts immediately (within seconds to a minute or so) after opening a door or window, I'd tend to suspect the atmosphere.

[paulcole]

Good old placebo seems just as likely.