Wonder what the physiological effects are? I notice very clearly the change in PPO (Partial Pressure of Oxygen) when running at 3000 M vs sea level

High CO2 levels reduce the nutritional quality of plants. They grow better but are less nutritious.

https://www.npr.org/sections/thesalt/2018/06/19/616098095/as...

Even medium levels of CO2 can influence our cognitive capabilities. And it gets worse the higher it gets.

isn’t the difficulty of doing physical exercice in altitude mostly due to oxygen depletion rather than co2 ?

i know it is recommended not to sleep in a room full of plants ( because they emit co2 during the night), but i must say i have no ideas what the scale is

The CO2 emission of a person/animal is more than the CO2 emission of the same weight of plants. If you are not afraid of sleeping with one [1] person of 150lb, you should not be afraid of sleeping with 150lb of https://en.wikipedia.org/wiki/Epipremnum_aureum or whatever interior plant is usual in your neighborhood.

[1] or more in a shared place like a university/military dormitory.

Indeed, that's why I mentioned the PPO (partial pressure of oxygen, autocorrected into the confusing "PPA" -- just edited my comment) which decreases at altitude. I was wondering if the CO2 level reduced the amount of available O2 to any physiological meaningful degree.