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?

I believe you're talking about the ratio of FEV1/FVC.

I'm afraid that at 70%, you are just below the line.

Sadly, damaged lung tissue cannot be repaired; however, once you quit smoking, the remaining tissue will be cleared and additional damage will be largely prevented (I believe it takes about a year to clear up).

Roughly speaking: Since smoking is not the only factor—despite being the most significant—

Air pollution is undoubtedly a factor if you live in, say, a smog-filled inner city.

Genetics also enters the picture. This is probably not very PC, but some people smoke continuously and still live long, healthy lives.

Although there is no known cure for COLD (chronic obstructive lung disease), the disease's progression typically stops once the "toxic" factors are eliminated or significantly reduced.

Programs for management are in place; these typically involve medication (such as flu shots or extra oxygen), exercise, and counseling.

However, as I previously stated, 70% is just below the borderline; 80% is generally accepted as normal, though not quite so.

I should point out that, although I am a biochemist, I am not a doctor, so in no way should you take my response as medical advice. Instead, see your general practitioner (GP) for further guidance, as he is familiar with you.

Quitting smoking can slow the progression of COPD, but it may not fully reverse existing damage. The extent of improvement varies among individuals. Regular monitoring and medical advice are crucial for managing COPD.