CO2 is such a small proportion of the atmosphere that I have a hard time imagining its active mechanism for cognitive impairment is the displacement of oxygen.

CO2 is such a small proportion of the atmosphere that I have a hard time imagining its active mechanism for cognitive impairment is the displacement of oxygen. It seems you would have to scrub the CO2. Luckily, the easiest way to do this even in a big city is just to open a window.