User blog comment:Evans0305/Game Theory: BioShock/@comment-3567720-20110820172550/@comment-2250991-20110820190247

True, but I think he might have missed some smaller details about that. Besides the Oxy-Fill Stations, they could still use the electrolysis idea in making more air. If you look closely around the walls and ceilings in Rapture's buildings, there are a lot of vents and maintenance devices that do everything for the citizens living there. These could have a number of uses, from temperature control, to even venting air from electrified water. But I think he might have missed the bellows and other vents, which could be what filters the waste Carbon dioxide, and from what he described, those do look like their function works like that.