• COPD is the leading cause of disability in the United States, and cigarette smoking is its main cause.
• The risk of COPD is directly proportional to the number of cigarettes smoked, but lung function improves with cessation of smoking, even after age 60.
Cigarette smoking is the main cause of COPD, which includes emphysema and chronic bronchitis. COPD is the fourth leading cause of death and the leading cause of disability in the United States. Women smokers are 13 times more likely to die from COPD, and male smokers have about a 12-fold increased risk (US Surgeon General, 2004). During their lifetime, smokers have about a 40% chance of developing chronic bronchitis. There may also be important racial differences, with African Americans, particularly females, having a higher risk than white smokers (Dransfield et al., 2006; Pelkonen, 2008). COPD among women is rising more quickly than among men, and since 2000, more women than men have died each year from COPD (CDC, 2008).
Changes in bronchi and the lung parenchyma are proportional to duration and intensity of smoking. Cigarette smoke inhibits ciliary activity of the bronchial epithelium and phagocytic activity of macrophages in the alveoli, resulting in decreased clearance of foreign material and bacteria from the lung, which leads to increased infection and tissue destruction. Smoking also releases inflammatory mediators, including oxidases and proteases, and inhibits pulmonary repair mechanisms. Even after age 60, smokers who quit have better pulmonary function than those who continue smoking. Lung function is inversely related to the number of cigarettes smoked over a lifetime. The rate of decline in pulmonary function is arrested by smoking cessation, the earlier the better.
• The risk of myocardial infarction is proportional to the number of cigarettes smoked.
• More than half of deaths from coronary artery disease are sudden, but the risk of sudden death is reduced immediately on cessation of smoking.
• Filter cigarettes and those with "low tar" or "low nicotine" do not reduce the risk of myocardial infarction.
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