How do we breathe on commercial airplanes? If humans breathe out carbon dioxide then shouldn’t we run out of breathable oxygen at some point?

Question

Might be a silly question, but I’ve always wondered how this works.

In: Other

Answer 1

Others have answers about how they regulate oxygen on an airplane, but I want to point out how long you can actually continue to breathe the same air. If you were locked in an airtight coffin, that minimal amount of air around you is enough to keep you alive for 5 hours.

If an airplane was sealed airtight, it would probably still maintain a full plane of passengers for about 12 hours.