Firstly let state that I am not getting at you. I know how easy it is to start and damned hard it is to stop. If you have read my ' I am back' thread, then this will make sense. I have the use of half my left lung and 3/4 of my right. Given the oxygen level of a normal person is 100%, what is my percentage? 50%-60%-70%, surely that is it. No, my percentage is 91%. Bet that made you think! If I walk 100metres it drops to 81% and takes about 5/8 minutes for me to recover. If these percentages were experienced by a normal person then they would be in deep doo doo, but if you suffer from any form of COPD then your body learns to cope with it. 9 percentage points is a very very small amount but at this level you are severely disabled. Best wishes. Bob F.