Stopping smoking is one of the best decisions you can ever make for your health. Your lungs are resilient organs and will begin to heal shortly after they are no longer exposed to toxic cigarette smoke. Within a couple weeks, your lungs will be able to clear sputum better, and your ability to breath will improve soon afterward. Later, your risk of developing lung cancer will start to fall. Although severely damaged lungs may not fully recover, smoking cessation is the best way to limit further deterioration.
Specialized lung cells secrete sputum, the sticky substance coughed up when you have a respiratory infection. Although sputum is often considered with disdain, it plays an important role in maintaining healthy lungs. A thin layer of sputum lines the air passages of the lungs, where it traps many harmful substances and germs. Cells underneath the sputum have small hairlike cilia that sweep sputum out of the lungs and toward the throat -- a process called mucociliary clearance.
Smoking paralyzes and eventually destroys some of the cilia, weakening this natural protective mechanism and increasing the likelihood of a lung infection. In a study published in the July 2011 issue of "Respirology," mucociliary clearance returned to normal by 15 days after stopping smoking, as the cilia regained their normal function. This improvement may explain why some people cough up more sputum than usual in the first few days after they stop smoking.
Smoking irritates the lungs, triggering an increase in mucus-producing cells and increased sputum production. Excessive sputum explains why smokers often have a wet-sounding smoker's cough. The extra sputum may also partially block the air passages, leading to difficulty breathing. Research evaluating the effects of smoking cessation on sputum production is very limited, but an article published in the "European Respiratory Journal" in March 2004 indicated that ex-smokers have fewer mucus-producing cells than current smokers. This suggests that smoking cessation reduces the number of these cells and thus the amount of sputum produced. Furthermore, coughing and excessive sputum typically decrease within 1 to 2 months after stopping smoking, according to the same article.
Reduced airflow in and out of your lungs is another consequence of smoking. This is detected by pulmonary function tests, including FEV1 -- the amount of air exhaled in the first second after taking in a maximally big breath. Smokers typically have an abnormally low FEV1, an indicator of airflow obstruction. This occurs because of airway narrowing secondary to sputum accumulation or swelling caused by inflammation. If emphysema develops, lung tissue destruction causes collapse of the air passages and further decreases airflow. Shortness of breath and wheezing are symptoms of a low FEV1.
Stopping smoking may improve FEV1 in as little as 1 week, according to a study in the October 2006 issue of the "American Journal of Respiratory and Critical Care Medicine." Wheezing and shortness of breath often begin to improve within 1 to 2 months, according to the March 2004 "European Respiratory Journal" article. After a year of not smoking, the FEV1 begins to fall but declines at the same rate as for nonsmokers, as reported in a study published in "American Journal of Respiratory and Critical Care Medicine" in February 2000. This decline reflects the normal, age-related decrease in FEV1, which is much slower than the rate of FEV1 decline in smokers.
Lung Cancer Risk
The National Cancer Institute reports that cigarette smoke contains at least 69 cancer-causing substances. Consequently, smokers have a much higher likelihood of lung cancer than nonsmokers, and the risk increases along with the amount of smoking -- number of smoking years and packs per day. Smoking cessation reduces the risk of lung cancer, but this occurs more slowly than improvements in other smoking-related lung effects.
A study published in the September 2015 issue of the "Journal of Medical Screening" noted that the risk of lung cancer 10 to 15 years after stopping smoking was approximately half the risk found in current smokers, but it was still about 15 times higher than in people who never smoked. Although the risk of lung cancer slowly declines as the number of years since stopping smoking increases, it will never reach that of those who never took up the habit. Nonetheless, the sooner you stop smoking, the lower your lifetime risk for lung cancer will be.
Now that you realize how stopping smoking will improve or even resolve many of the harmful effects on your lungs, you may be more convinced than ever to stop smoking. Talk with your doctor about ways to help you accomplish this. The National Cancer Institute and American Lung Association each have free smoking cessation telephone hotlines. There are several strategies to aid smoking cessation, ranging from nicotine-containing gum, sprays or patches to prescription medications. A March 2016 "Cochrane Database of Systematic Reviews" study that analyzed the pooled results of 53 previous studies concluded that a combination of behavioral therapy and medications was particularly likely to lead to success in stopping smoking.
Never Too Late
If your attempts to stop smoking don't succeed the first time, it is never too late to try again -- even if you have chronic obstructive pulmonary disease (COPD) or emphysema. The destroyed lung issue cannot be replaced, but you can avert further damage by quitting smoking. And even if you have been diagnosed with lung cancer, stopping smoking while it is still in the early stages can reduce the likelihood that the cancer will recur after successful treatment or that a completely new lung tumor will occur in the future, as discussed in an article in the May 2011 issue of the "International Journal of Chronic Obstructive Pulmonary Disease."
Reviewed by: Tina M. St. John, M.D.
- Respirology: Reversibility of Impaired Nasal Mucociliary Clearance in Smokers Following a Smoking Cessation Programme
- European Journal of Respirology: The Impact of Smoking Cessation on Respiratory Symptoms, Lung Function, Airway Hyperresponsiveness and Inflammation
- American Journal of Respiratory and Critical Care Medicine: Small Airway Function Improvement After Smoking Cessation in Smokers Without Airway Obstruction
- American Journal of Respiratory and Critical Care Medicine: Cessation and Lung Function in Mild-to-Moderate Chronic Obstructive Pulmonary Disease
- National Cancer Institute: Harms of Cigarette Smoking and Health Benefits of Quitting
- Journal of Medical Screening: Lung Cancer Risk by Years Since Quitting in 30+ Pack Year Smokers
- The British Medical Journal: Smoking, Smoking Cessation, and Lung Cancer in the UK Since 1950: Combination of National Statistics With Two Case-Control Studies
- Journal of Clinical Oncology: Lung Cancer Risk Reduction After Smoking Cessation: Observations From a Prospective Cohort of Women
- Cochrane Database of Systematic Reviews: Combined Pharmacotherapy and Behavioural Interventions for Smoking Cessation
- International Journal of Chronic Obstructive Pulmonary Disease: Improved Patient Outcome With Smoking Cessation: When Is It Too Late?