Oh I'm not interested in hermetically sealing my apartment, there are no worries of normally constructed buildings being able to withstand a meaningful difference in oxygen pressure between inside and outside. CO2 pressure though can easily be increased by a large factor (5x is easy) and maintained with humans inside and closed doors and windows.

PM2.5 is easy to maintain with HEPA filters.

CO2 is not easy to maintain without forced ventilation, and really I would like to try inside levels lower than outside levels. (say 300 ppm)

I’m intrigued by the idea of chemically scrubbing co2 at home as well. Hepa filters are easier to use than I’d expected. The next big step is co2 reduction.

Maybe get in touch

Don’t those requirements conflict? Maintaining a partial pressure difference between inside and out for CO2 but simultaneously preventing a partial pressure difference in O2? I guess with a large enough scrubber running constantly it might work but it will be highly inefficient - a bit like running AC at full blast with open windows.

They do to a degree but overall composition of the atmosphere has so much oxygen and so little co2 that the dynamics are quite different.

There’s something like 50x as much oxygen in the atmosphere as co2 so a relative change of 1% nominal value will correct itself fifty times faster for oxygen than for co2 between outside and inside (ok a wild simplification, but still)

The result is that without really intense sealing it’s basically impossible to make a difference in indoor oxygen levels whereas with even a cracked window i can maintain co2 levels two to three times outdoor concentrations in my apartment.

Running a co2 fixer with the place shut up would be more like... running the air conditioner full blast with the place shut up. Yes there would be losses but they would be relatively contained.