Gee you guys have gotta go back to school there. Oxygen is stored in bottles, you know SEP stuff & Air is all around us in the atmosphere
I wonder why the cabin crew would go 'running' down the isle/s if it where just condensation?
Perhaps the skipper was an ex 4 engined 'tank' driver (146)where those engines seemed to produce smoke inside as well as outside of the airframe so he got nervous
Wmk2