I recently asked a question about whether there were studies on the effects of reduced CO2 level air and got what sounds like a good answer:
The answer posted to the above question states that there is no reason to expect low inhaled CO2 levels to even make a difference in the relative levels of CO2 in the lungs, with are ~100x higher than in the ambiant air. This seems like a rational argument.
But with further thought that argument seems inconsistent. If average CO2 levels in the air are around ~400ppm, just 3x that number, ~1200ppm, is known to be associated with drowsiness and complaints of poor air quality (if my research is correct).
If the argument above holds, that reducing CO2 levels in the air from ~400ppm to ~0ppm, isn't going to significantly affect the ratio of CO2 in the lungs, then why doesn't that argument hold also with a seemingly small increase of 3x CO2 levels in the air (as compared to the 100x levels in the lung already)?