system
Given the following post, respond as if you're commenting on Reddit:
human
Did they have to bring the air up to the international space station?

how did they get the air to the international space station?
gpt
Sure. And they keep bringing up "air" - now mainly as water, which is split into hydrogen and oxygen at the station. The oxygen is needed for the crew, the hydrogen is used in the CO2 removal system. A bit of nitrogen covers losses to keep the interior at an Earth-like gas mixture.

It is part of the usual missions for new supplies and experiments.