What Happens to Your Lungs When We Quit Smoking?

According to the Centers for Disease Control and Prevention (CDC), smoking can cause lung disease by damaging smokers' airways and the small air sacs (alveoli) found in their lungs. Most smokers are paying attention to their lung health now. So what's the difference between smokers' lungs and non-smokers' lungs?

The lungs of non-smokers are light red in color, soft and elastic; there may be some light black spots on it, which are traces left by atmospheric pollutants and fine dust particles.

Source: scientificanimations.com

While the lungs of smokers are full with black spots on the surface, which is caused by substances such as cigarette tar, radioactive particles and dust attached to the lungs.

Source: indianexpress.com

In this article we will address that what will happen to our lungs after quitting smoking.

After Quitting Smoking, the Lung can Recover Part of Its "Self-Cleaning Function"

The air and smoke we breathe in need to go through layers of filtration before reaching the lungs.

First Layer: Nose

Nasal hair can block large particles and impurities, and nasal mucus can stick to smaller particle and prevent them from entering the airway.

Second Layer: Trachea and Bronchus

The inner walls of trachea and bronchus can produce mucus and stick dust particles together; the "cilia" inside the bronchus can swing up rhythmically to expel mucus with dirt by coughing or sneezing.

Last Layer: Lungs

The last line of defense is the immune cells in the alveoli, which can devour particles or kill bacteria.

Although the lung has a relatively perfect defense system, it really has nothing to do with "tobacco smoke".

  • Tobacco smoke is inhaled from the mouth without nasal filtration.
  • Tobacco smoke particles will make trachea and bronchus secrete too much mucus, resulting in airway blockage.
  • Within a few hours after smoking, ciliary movement will slow down, resulting in poor cleaning effect.
  • Tobacco smoke will damage the alveoli and weaken the immune system.

While after quitting smoking, the self-cleaning function of the lung will gradually improve.

  • Without the stimulation of tobacco smoke particles, the secretion of mucus from the trachea will be reduced and the breathing will be more smooth.
  • Cilia will move faster, which can better remove mucus secretion.
  • The immune system in the alveoli will be enhanced, so that it can swallow more particles and kill pathogens harmful to the body.
In general, after quitting smoking, the waste deposited in the lungs tends to be "less and less".

    Additionally, keep fresh and clean air around will benefit for improving lung functions.

    Can the Lung Function Recover as Before Smoking If Quit Smoking for Long Enough?

    It is difficult to recover lung function after smoking cessation as before smoking. Because lung function will naturally decline with age, which has been declining since the age of 20.

    Moreover, smoking can also cause some irreversible effects on lung function.


    Long-term heavy smoking may lead to the destruction of alveolar walls and the permanent expansion of alveoli and alveolar ducts.

    Chronic Bronchitis

    Harmful substances such as tar, nicotine and cadmium contained in cigarette smoke can damage respiratory mucosa, cause bronchial spasm, make bronchial wall fibrous thickening, and the lumen becomes narrow or even closed.

    The Earlier You Quit Smoking, the Greater the Possibility of Lung Function Recovery

    The degree of irreversible damage to lung function is closely related to the "smoking index"; The greater the "smoking index", the higher the degree of irreversible damage to lung function.

    According to a paper named Lung Function Decline in Former Smokers and Low-intensity Current Smokers: A Secondary Data Analysis of the NHLBI Pooled Cohorts Study published on the Lancet Respir Med in 2019, a light smoker (<5 cigarettes a day) may lose as much lung function in 1 year as a heavy smoker (≥30 cigarettes a day) may lose in 9 months.

    According to the data released by the American Cancer Society:

    • The risk of lung cancer 10 years after quitting smoking is about half that of smokers.
    • After 20 years of quitting smoking, the risk of chronic obstructive pulmonary disease (chronic bronchitis, emphysema) will drop to the level of non-smoking.
    • After 30 years of quitting smoking, the risk of lung cancer will drop to the level of non-smoking.

    Therefore, the earlier you quit smoking, the more likely you are to improve your lung function.


    1. U.S. Department of Health and Human Services. How Tobacco Smoke Causes Disease: What It Means to You. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2010 [accessed 2017 Apr 20].

    2. Cari Nierenberg. Do Smokers' Lungs Heal After They Quit. Live Science. 2017.6.30

    3. Elizabeth Oelsner,et al. Lung function decline in former smokers and low-intensity current smokers: a secondary data analysis of the NHLBI Pooled Cohorts Study. Lancet Respir Med, published online Oct. 9. 

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