Without meaning to drift the thread, I did differenciate quite clearly between unfit and unhealthy. Stupid to smoke? Obviously... But not too stupid to be well aware of the potential consequences. I'm not remotely defending it.
All I was saying is that some are most certainly more susceptable to lack of o2 than others. Smoking seriously reduces the ability to get o2 into the blood, yet I find I am far from the most susceptable to hypoxic symptoms. Not a boast, just an observation.