This isn’t worth worrying about. The atmosphere has a CO2 concentration of about 413 ppm. The International Space Station operates at a maximum CO2 concentration of over 5000 ppm. 5000 ppm is also the maximum safe CO2 concentration recommended by OSHA and the approximate average CO2 concentration aboard nuclear submarines. This still might be slightly too high—astronauts and submariners commonly report headaches, for instance—but it’s about ten times the concentration of the outside atmosphere and the health effects are a little hard to measure. Plus, the people in these conditions are still capable of safely operating space stations and nuclear submarines, which is not a cognitively easy feat. If the CO2 concentration of Earth’s atmosphere got that high, we’d have much bigger problems.