i would assume most of the c02 your putting in the air is sucked out pretty quickly with a portable a/c.I have a portable that has a exhaust, I got bad odor from there but I've since made a small inline carbon scrubber that I'll put on that ac exhaust IF I'm needing to run it at all next time there may be an odor there. I know the ac exhaust wouldn't handle pushing the air thru an inch of carbon or so I'll boost it with the light fan helping to pull it thru. But still my question would be how much co2 am I losing, if theres an odor obviously theres also gonna be gas exhausted.