Cigarette smoking damages the lungs in a variety of ways. Quitting smoking, on the other hand, results in favorable changes and healing within the lungs that decrease the risk of disease. The lungs contain several cell types that respond to changes in their environment. Modifications to the lungs begin to take place almost immediately when you stop smoking and continue for years -- an example of the human body’s remarkable ability to heal itself. The sooner you quit, the better the chance for reversing the harmful effects of tobacco smoke on the lungs.
Airway Mucus Clearing
Tiny hairlike projections on the surface of the airways -- called cilia -- clear mucus and debris from the lungs. Cilia are damaged by tobacco smoke, rendering them unable to effectively clear particles and move mucus through the airways. Cilia begin to regain function within weeks after quitting smoking, with continued improvement for at least several months. This change typically leads to decreased coughing and fewer respiratory infections due to cleaner airways throughout the lungs.
Reduced Lung Inflammation
Smoking causes inflammation of the airway walls, leading to thickening and increased mucus production. Inflammation is a key component of smoking-related lung diseases, such as chronic obstructive pulmonary disease, or COPD. Airway inflammation diminishes after quitting smoking. With that comes fewer lung infections and improvement in disease symptoms. Additionally, when the airways return to a normal thickness, lung function improves as well. Oxygen taken in from the air can then more easily be moved to other parts of the body.
Improved Lung Function
A key feature of COPD is an inability to efficiently move air in and out of the lungs. Quitting smoking allows small airways within the lungs to become more elastic. Improved elasticity permits the lungs to hold more oxygen-rich air as it is breathed in. Emptying the lungs while exhaling is also more effective, and this allows for more efficient expulsion of carbon dioxide -- a byproduct of normal metabolism -- from the body. Improved lung function can lead to an increased capacity for exercise and physical work .
The heightened risk of lung cancer in people who smoke is due to abnormal changes in the genes of lung cells caused by the chemicals in cigarette smoke. Damage to lung cells builds up over time, and eventually can lead to a cancerous tumor. Stopping smoking gives lung cells a chance to repair already-sustained genetic damage -- and additional damage from ongoing exposure to tobacco smoke is avoided. The risk of lung cancer falls within 5 years of quitting. Ten years after quitting, lung cancer risk decreases by one-third to one-half compared to people who continue to smoke, according to the Centers for Disease Control and Prevention.