My FEV lung function is 70%. I am 34 years old and I have smoked for 20 years. If I stop smoking now, can COPD be reversed?
The short answer is no...
I think you are referring to the FEV1/FVC ratio?
With 70%, you are slightly below the borderline I'm afraid...
Unfortunately, damaged lung-tissue will not be replaced.
However, once you stop smoking the remaining tissue will be cleared, and further damage will be more or less avoided.(it takes about a year as far as I can remember, but I might be wrong)
More or less: Because smoking, though by far the most important, is not the only factor:
If you live in, say, a smog-ridden inner city, air pollution is certainly a contributing factor.
Also, genetics enter into the fray: probably not very PC, but some people smoke(d) all their life, and still reach old age without mentionable problems.
There is no cure for COLD (Chronic Obstructive Lung Disease, no pun intended...), but once the "toxic" factors have been removed or greatly diminished, progression usually halts.
There are management programs in place, usually involving excercise and counseling, and medication (e.g. flu-jabs, supplemental oxygen).
But, as I mentioned, the level of 70% is slightly below borderline: 80% is considered normal, though not generally agreed on...
I have to mention this: I am a biochemist, but NOT a doctor so don't take my answer as medical advice in any way or form. Go and see your GP for more advice. He knows you, after all....