Some years ago a friend, a two pack a day smoker had a non-smoking couple as house guests. He awoke in the middle of the night with a very serious headache. He checked on his guests and they were unconscious. Emergency medical transported them to the emergency room. the attending physician noticed my friends cigs in his pocket, established he was a heavy smoker and solved the problem. The pool heater had malfunctioned and was filling the house with carbon monoxide. My friend, the heavy smoker, had a far greater tolerance for carbon mono. Cigarettes saved 3 lives this particular night. I thought of this in regard to another post concerning snuff and pain. Snuff, with no Carbon Monoxide(CO?) should have no ill health affects.