The most popular thing that came up in the search engine after I put in "smoking damage regeneration lung" was and article called "Teenage Smoking Causes Permantnent Lung Damage" that says:
Is damage caused by smoking permanent?
Not if the smoker stops soon enough. In smokers who have stopped before the onset of irreversible heart and circulatory disease, the body begins to repair itself. Normally, after a year of non-smoking, the risk of a heart attack is reduced by half. After 10 to 15 years of non-smoking, it's about the same as that of someone who has never smoked.
A study published in the Journal of the National Cancer Institute has shown that smoking in the teenage years causes dramatic and lifelong DNA damage in the lungs. In fact, the young smokers could be at a permanently higher risk of developing lung cancer, even if they later quit.
This information comes at a time when surveys by the Centers for Disease Control and Prevention (CDC) indicate that the percentage of high school smokers rose from 34.8 percent in 1995 to 36.4 percent in 1997.
In this study, researchers tested for DNA alterations in the non-cancerous lung tissue of patients being treated for lung tumors. The healthy tissue was tested for the number of DNA alterations per 10 billion cells. Researchers found that former smokers who started between age 7 and 15 had an average of 164 genetic alterations. Ex-smokers who started between ages 15 and 17 had on average 115 alterations. And among former smokers who did not start smoking until after age 20, the number of DNA alterations averaged 81.
Experts say that DNA alterations in the lung tissue occur when chemicals in tobacco smoke fuse with genes in the DNA and cause mutations that can significantly increase the likelihood of cancer.
When smokers quit, within twenty minutes of smoking that last cigarette the body begins a series of changes.
At 20 minutes after quitting:
blood pressure decreases
pulse rate drops
body temperature of hands and feet increases
At 8 hours:
carbon monoxide level in blood drops to normal
oxygen level in blood increases to normal
At 24 hours:
chance of a heart attack decreases
At 48 hours:
nerve endings start regrowing
ability to smell and taste is enhanced
The first year after quitting:
At 2 weeks to 3 months:
walking becomes easier
lung function increases
1 to 9 months:
coughing, sinus congestion, fatigue, shortness of breath decreases
excess risk of coronary heart disease is decreased to half that of a smoker
Long-term Benefits of Quitting
At 5 years:
from 5 to 15 years after quitting, stroke risk is reduced to that of people who have never smoked.
At 10 years:
risk of lung cancer drops to as little as one-half that of continuing smokers
risk of cancer of the mouth, throat, esophagus, bladder, kidney, and pancreas decreases
risk of ulcer decreases
At 15 years:
risk of coronary heart disease is now similar to that of people who have never smoked
risk of death returns to nearly the level of people who have never smoked