I'm in the indoor air quality business. This is real.

A good way to think about CO2 is as a proxy for dirty air. CO2 is easy to measure but what it really means:

The next breath you take has: - already been inhaled and exhaled by others several times. - contains remnants of their farts, burps, off-gasing from everything they are wearing, have, everything in the room, etc. - may have presence of other gases like radon in the winter, mold spores, g-d knows whatever else. - co2 itself has negative effects but mainly it's a signal of what else is probabilistically in your air, poor ventilation.

Florence nightingale the inventor of modern nursing wrote that making indoor air as close as possible to outdoor air (without freezing the patient) is the best and most overlooked input to wellness. I believe this is still true.

Weirdly there are people who for some reason are hell bent on denying the air quality as an input to health and cognition. The simplest way to reason about it is: the argument for organic food is the less toxin-like stuff in it the better. Same for filtered or spring water. We often fail to quantity the impact exactly but we (logically) know that less toxin is better. For some reason we hold a much higher bar for "blaming the air" which doesn't make sense.

By volume we consume exponentially more air than food or water, and it enters the blood stream faster and more directly so obviously it impacts us. The EPA ranks indoor air quality as a top risk.

Ironically we are obsessed with outdoor air quality and if you have allergies to things like pollen that's a real concern but in most cases outdoor air is the baseline for what's indoors + other shit is added.

I find that there are people who say "wow air quality here is bad" and there are people who say "oh man I'm tired lately" without being able to attribute it, but I don't ever see anyone thriving in what is objectively bad air.