Is it legal to own oxygen?

Be careful with pure oxygen. Although oxygen itself is not flamable, in presence of pure oxygen, normally non-flamable items burn, and things that normally do burn, burn with explosive energy.

Try calling medical supply store and find out if you need a prescription for a purchase.

The air we breath is a mix of oxygen and other components to be breathing pure oxygen on a regular basis isn't that good for you so before you purchase a canister I would find out how healthy doing something like that can be.

It is not illegal to own oxygen, but breathing quality oxygen is classified as a drug and in most places you must have a prescription to acquire it. There are oxygen bars and I am not sure how they go about getting it and dispensing it, but you may want to ask someone that runs one, they may be able to point you in the right direction.

Eh, I imagine compressed oxygen is in limbo in legality. "Intended purpose" and all that.

pretty sure you can, you can own a torch which uses non-medical oxygen so...

our bodies deteriorate quicker with just oxygen

that is why there are anti oxidants to help our bodies fight that effect.