Kurt Ullman wrote:

If the question is can someone go to the local Ox-shop, tell the
person they want welding oxygen, take it home and use it for medical,
yeah. Just like you can use medications for off-label uses, but you take
on extra risks by doing that.

The chief extra risk is that someone will claim that the welding O2 will
kill you for some nebulous reason. I guess the medial O2 atoms are
different from the welding O2 atoms.