AlvinofDiaspar
Moderator
Oxygen is extracted from the air by cryogenic distillation. You chill air until the 20% that is oxygen condenses to liquid, allowing it to be isolated. This is something that needs to be done on an industrial scale.
Not quite the only way nor only in industrial scale:
Oxygen concentrator - Wikipedia
en.wikipedia.org
India is getting some of these right now.
AoD