But it's probably better if you invested into a counterflow heat exchanger for ventilating your home. You can recover a large part of the heating/cooling energy.
Also I would prefer levels lower than outside, obviously air exchangers will necessarily be worse than just being outside.
Current levels outside as measured by my device just now are about 450ppm.
Like so many things I think it is a small effect; it's not like I can go anywhere for a week to experience 300ppm air.
I haven't gone to the levels of designing experiments and data tracking on myself. The fact that I've lived with allergies and a broken nose most of my life probably hasn't helped my personal respiration characteristics.
My literature searches haven't had much success thus far, lacking a chemistry degree hasn't helped. I have found some things but not enough to come to any sort of engineering designs. I'm assuming it's one of those things that's almost too simple for anyone to have bothered writing a paper about unless they had the exact sort of ideas I did. (OR they're using terms that I haven't been able to come up with yet)
With small device I could drop CO2 levels to zero in volume of a gargabe bag in few minutes.
But that would give you oxygen rich atmosphere. You'd probably want to add some inert gas to that. Nitrogen preferably. Are there nitrogen concentrators?
Also all of that is probably really dangerous because human body doesn't detect oxygen level, just CO2 level. So you might easily pass out and suffocate without any warning if your oxygen supply unit get damaged but your nitrogen supply unit doesn't.
More heat than is common for home appliances I know! A commonly referenced stat is 825 C. There's really a gradient: https://en.m.wikipedia.org/wiki/Calcium_carbonate#Calcinatio...