I thought this is supposed to show that he is sort of a neurotic person that thinks all the world is bad.
Even outside you cant get fresh air because of the cars etc.
So when he gets home first thing he does is to breathe some pure oxygen.

he uses it as a kind of inhaler. He gets all frustrated and the oxygen helpsps

pure oxygen supposedly helps you to think clearer.

well he continues to smoke puff throughout the film. feeling from his reaction to jules you get the impression that ganja is something that hes trying to give up rather than something he is against morally/socially.

Sorry, how was it clear he was a weed smoker? Because he said "grass is fine" or for other reasons? I didn't really get a clear notion of his attitude towards drugs in the film.

yeah it makes sense that hes using it to get high. however its pretty clear he is a weed smoker as he by 'dope' he means drugs generically and hes kind of taking the piss when he says it. he also says 'grass is fine' or words to that effect so geting high is something that he does in general.

He IS using it to get high. He just said he doesn't smoke dope because it "kills the revolutionary spirit", but I don't think anyone has proven that oxygen is bad for your brain.
He stole the oxygen machine. Not because he has lung problems, but simply to get HIGH.
You said he did it "to get energy", that's a reason people do cocaine. Meaning = drug high.

i don't think it's for getting high because he doesn't like getting high. he barely smokes and i doubt he would huff because drugs "kill the revolutionary spirit." i know it doesn't really make sense if he's not using it to get high, but it doesn't really make sense that he is using it to get high. i don't know maybe i'm thinking about this too much.
i think he might be using it for energy. i don't know if that would give you energy but it makes sense because he's out all night in his van and probably doesn't get a lot of sleep.
"I'm people who know people."

cheers for the post. nah i havent heard of using oxygen to get high. im guessing its a bit like doing a wippet(laughing gas) then?

its basically like a method to get high, i dont know if your from the US or not but we have oxygen bars here.
"i dont patronize bunny rabbits"