Smoking permanently damages the airways

Chronic obstructive pulmonary disease (COPD) is a lung disease that occurs following a progressive deterioration of the airways.   This deterioration is usually due to tobacco smoke and, less frequently, to pollutants and dust contained in the air. The illness is characterized by severe shortness of breath (dyspnea) and is incurable, but measures can be taken to slow down its progress. The most important of these measures is smoking cessation.

Test your own breathing on (french)


Who is affected by this illness?

COPD affects a very large number of people and is considered to be the fourth or fifth biggest cause of death in the industrialized world. About 9 to 10% of the population aged 40 or over suffer from this complaint (Halbert et al., 2006). Smokers are the first to succumb. According to the Ligue Pulmonaire (a lung association in Switzerland), “some 90% of patients suffering from BCPO are smokers or ex-smokers. Among the remaining 10%, COPD is either caused by hereditary factors or by other lung irritations such as inhaling large quantities of harmful dust (in farming, mines, etc.) or toxic gases in industry. In some cases, BCPO can also be the late consequence of long-term asthma”.

What’s more, many people suffer from COPD without realizing it. The disease is insidious, evolves gradually, and often goes undiagnosed until the latter stages of its development.

A progressive disease

COPD causes a progressive narrowing of the airways. In the early stages of the illness, although the pulmonary lesions are already present, it is probable that no symptoms will appear and the person will not realize that he or she has already lost some lung capacity. A pulmonary function test using spirometry liens_externe_bleu-sur-blanc  allows us to measure the potential loss of lung function. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) defines four stages of development of the illness, from mild COPD which does not produce symptoms to very severe COPD where the wellbeing of a patient is seriously compromised, to the point where his or her life is in danger. You can find the description of these four stages liens_externe_bleu-sur-blanc(in French) on the website of the Ligue Pulmonaire (lung association).

How does tobacco smoke affect the airways?

COPD is the permanent loss of lung function following prolonged exposure to harmful substances and chronic lung inflammation. Chronic bronchitis and emphysema contribute jointly to the appearance of COPD.

The bronchi are covered by a protective mucous membrane made up of cells: ciliary cells, which repel dusts and microbes by coordinated movement of their cilia, and glandular cells which secrete a substance (mucous) to trap impurities.

Tobacco smoke contains toxic substances and irritants which disrupt and then destroy this protective covering:

  1. In the early stages of smoking, the cilia beat in a less coordinated fashion and later, they become paralyzed. Coughing therefore becomes the only way of expelling the particles.
  2. As the ciliary are destroyed, the irritants contained in cigarette smoke prompt the glandular cells to secrete more mucous.

This double action on the mucous covering causes a build-up of secretions which obstruct the airways and harm respiratory function. This symptom of bronchitis is reversible at first, but over time it becomes irreversible.

In addition to this, tobacco has a harmful effect on the pulmonary alveoli and causes centro-lobular emphysema. The alveoli walls progressively disappear, thus decreasing the quantity of air that can be inhaled and exhaled (ie. a reduction of the surface area).

Chronic bronchitis or pulmonary emphysema can be warning signs of COPD. For this reason, we recommend that you see your doctor if you cough regularly and become very easily out of breath.

According to the Ligue Pulmonaire (lung association), “in COPD cases, the airways and the bronchi shrink irreversibly and this contraction gets worse over time. It causes an increase in air resistance in the airways, lung function is impaired and the patient feels out of breath. In the later stages on the illness, the patient may also suffer from a lack of oxygen”.


The lung, a fabulous natural filter

Our lungs take in on average 6 liters of air every minute! This air obviously contains the oxygen our body needs, but it also contains a large amount of impurities and dust. Luckily, our lungs possess a fabulous protection system which purifies this air and stops the lungs from being damaged prematurely. When tobacco smoke is inhaled, the amount of dust and toxic substances that need to be eliminated dramatically exceeds the tolerable threshold on the one hand and disables a part of the defense system on the other hand (notably by the destruction of ciliary cells), which is why smoking leads to a premature degeneration of the respiratory system.

As a guide, when Carbon Monoxide is measured with a CO-tester which measures in ppm (parts per million), the value recorded ranges between 3 and 8 in cities. Any higher than 8 and the air is considered to be polluted. When a smoker exhales, however, the value recorded can range from 6 to 50 ppm, if not even higher!

What treatments are available?

Smoking cessation is the main way to prevent or slow down the progression of COPD. If the disease is already well developed, various measures taken hand-in-hand with smoking cessation can improve lung function and the wellbeing of the patient: physical exercise and breathing exercises coupled with medication can offer some relief to a person suffering from COPD (Anthonisen et al., 1994). Furthermore, vaccinations help to ward off viral and bacterial infections to which the airways are particularly prone.

In the end, the best way to halt the development of the disease, or even to prevent it from occurring in the first place, is to stop smoking. To achieve this, the same approach is valid for all sufferers – an analysis of 5 studies arrived at the conclusion that combined smoking cessation treatments (nicotine replacement therapy, bupropion, etc.) accompanied by adequate psychological support, increase the chances of quitting smoking and of COPD taking a favorable course of development (Van de Meer et al., 2003). Another review of the literature arrived at the same conclusions while suggesting that the best way to achieve long-term smoking cessation among COPD patients is a combination of nicotine replacement therapy and an intensive relapse prevention program (Wagena et al., 2004).

The long-term benefits of quitting smoking for COPD sufferers are well known. A review of the literature highlighted that smoking cessation significantly slowed down lung function decline and greatly increased quality of life, even for those suffering from very severe end stage COPD (Godtfredsen et al., 2008).

Short-term effects

Smoking cessation improves the long-term prognosis for COPD evolution. But does it also bring immediate benefits? A survey carried out by Jean-François Etter on the website enabled us to conclude that smoking cessation is followed by a rapid improvement in respiratory symptoms (2009). The 252 participants who stopped smoking reported after 30 days of not smoking that they coughed less (51.6% before quitting, 15.5% after 30 days), that they coughed up less phlegm in the morning (from 47.6% to 19.4%), that they felt less out of breath after walking quickly or climbing stairs (from 75% to 48.4%) and that their breathing was less wheezy (from 33.7% to 10.3%).

Do you suffer from breathing problems?

A persistent cough and morning phlegm not accompanied by a cold are the first symptoms of COPD. Often, they are attributed to a simple “smoker’s cough”. Over time, and if the person does not stop smoking, the disease develops. Breathing becomes more and more difficult for them (dyspnea). At first, they only feel out of breath during intense physical activity, and then gradually the slightest exertion or the simple act of walking provokes this dyspnea. The progression of the disease is insidious and its very slow development means that many people do not take it seriously or go to see their doctor about it.

There are some online questionnaires which allow you to assess your breathing and found out if you may already be suffering from a chronic respiratory problem, eg. the Swiss lung association website (Ligue Pulmonaire Suisse)liens_externe_bleu-sur-blanc .

Here at, you can also test your breathing and fill out a questionnaire which will help us to advance our research. This questionnaire forms part of a study on the beneficial impact of smoking cessation on the respiratory tract.

Breathing questionnaire

The results of a similar questionnaire have already been published in a scientific journal (Etter, 2009).


About COPD

  • (in French)


Studies on BPC

Author: Grégoire Monney

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