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

It’s a mixture of fresh air from outside, and recirculated air. Here’s an interesting article that explains.

https://www.askthepilot.com/questionanswers/cabin-air-quality/