Greg, as an asthmatic I miss your point totally. I am never locked in   a garage with four or five or even more cars with their engines switched on in a confined space. I understand your basic point, but you can't seriously apply it to a small room, unless you're an addict looking for any excuse for a habit you know is doing you harm. I've just seen a fine human being die of alcoholism and none of his friends could make him quit. He was hugely intelligent but would do anything and use any arguement to avoid facing the fact that he was addicted to a harmful drug. You can't call asthmatics hypocrites. You could try to understand our point of view, as we understand your addiction if you are a smoker.