Cigarette smoking is by far the most
commonly encountered risk factor for COPD. Cigarette
smokers have a higher prevalence of respiratory symptoms
and lung function abnormalities, a greater annual rate of
decline in FEV1, and a greater COPD mortality rate than
nonsmokers. Pipe and cigar smokers have greater COPD
morbidity and mortality rates than nonsmokers, although
their rates are lower than those for cigarette smokers11.
Other types of tobacco smoking popular in various countries
are also risk factors for COPD17,18, although their risk
relative to cigarette smoking has not been reported. The
risk for COPD in smokers is dose-related12. Age at starting
to smoke, total pack-years smoked, and current smoking