Quote Originally Posted by factotum View Post
There's a fairly common trope in SF series where you have a space station of some kind, and the lives of the people on board are maintained by having green vegetation around to exchange carbon dioxide with oxygen. I was just wondering about this, and I ask the Playground if anyone knows: has anyone ever worked out just how large an area of green plants would be needed to maintain the oxygen levels for a single person? Just curiosity, mainly, because I was wondering how much of the interior of a station would have to be given over to vegetation and how much could be used for people.
Too many open variables to provide a simple answer.

Different plants produce oxygen at different rates, and then the same plant's oxygen release can vary depending of the enviroment conditions (in particular sunlight).

Then different people may have different oxygen needs. Like people living in tall mountains can grow used to living with lower oxygen concentrations in the air.

And of course it also depends of whetever you want to keep that person at peak condition or just barely enough oxygen to keep them awake. If the human is expected to do a lot of heavy lifting they'll need more oxygen but if they just need to monitor a bunch of machines they'll need less and so on.