oxygen

Yesterday I was talking with a friend about people we've known who needed to use an oximeter or liquid oxygen or something like that. Oxygen is a funny thing... something we take for granted, but also something we can't live without. It's kind of a double edged sword too- it's so flammable that in its concentrated form, it can catch fire and kill you. Really perplexes me when I see older people on oxygen puffing away on their cigarettes- do they have a death wish?