[The habit of smoking--a sure step towards COPD].

Smoking is a major risk factor for respiratory disorders, especially COPD, often diagnosed in advanced stages, when lung function impairement has already reached less than 50% of its normal value. Presently, all diagnostic and therapeutic guidelines mention relationship between tobacco consumption and COPD and strongly recommend smoking cessation as mandatory and beneficial in COPD. The condition constitutes an important public health topic, among other smoking induced chronic diseases, if we think only to high costs of taking in charge attributed to frequent and/or severe exacerbations. Most of these exacerbations are caused by Pneumococcus, Haemophilus influenzae or Moraxella catharalis and express chronic inflammation. Consequently, muco-ciliary clearance is unbalanced as oxidative stress due to tobacco smoke exposure and non reversible bronchial structure changes progress. Severity and evolution of COPD in smokers are related to early smoking intake, gender, number of packs-year, type of tobacco product used, precocity of giving up smoking. Even if a late achievement, smoking cessation is beneficial to stop lung function decline and reduced frequency and intensity of exacerbations. As well, efficacy of bronchodilator medication is greater and risk to cardio-vascular diseases is much more diminished, after stopping smoking.