Will a smoker’s lungs clean themselves if they quit smoking and how long does it take?

That's what the medical system was telling us in the 1970s. Turned out it wasn’t quite true — for a heavy smoker, the damage may be permanent,

BUT this in no way says you should give up & not quit, because one thing that quitting does is cease the continuing damage being caused every time you suck that smoke into your lungs.