I will update my post with the accurate answer. But from the top of my head, the lungs of a smoker will heal either 2, or 4 years after completely stopping.
Congratulations to you however, smoking is a sad way to kill yourself (no offense intended for you smokers out there, but it is what it is). I've particular began to dislike the idea of smoking after taking my exercise science class and dealing with the almost psychotically dangerous (in the viewpoint of a smoker) but justified respiratory exercise teacher. He was involved in research for a clinic with kids who have Cystic fibrosis, whose lives will never be as long as ours because their lungs will eventually die out. He told us the reason why he was so passionate about smoking was because the thought of seeing one intentionally taking out their own lungs, when he has to deal with these children whose lungs are failing them because they were born with it.
I hope you haven't smoked too much to the point that your reserve lung capacity is damaged, after a certain point, your lungs will never heal. At this point, breathing becomes such a difficulty that your energy expenditure in an attempt to intake oxygen becomes too great for your body to handle, to the extent that even the energy intake from food will not be able to keep up with it. Which then will result in painstakingly slow death with every breath a huge difficulty. Yea, my teacher was quite cynical about that stuff.
And Yes, this is an odd attempt of scaring you from thinking about smoking again. Keep up the good work
