Int. J. Environ. Res. Public Health 2009, 6 212 Despite the ongoing inflammatory process, there is increasing evidence that the rate of development of COPD can be reduced when patients at risk of developing the disease stop smoking [25]. The first indications came from longitudinal cohort studies which showed that subjects who continued to smoke had a much steeper decline in lung function than those who had stopped smoking [26, 27]. The Lung Health Study confirmed that smoking cessation could reduce this smoking-related precipitous decline in lung function [28]. It was a randomized clinical trial designed to determine the potential benefits of smoking cessation. All participants had, as an inclusion criterion, asymptomatic airway obstruction. The special intervention participants received a smoking cessation program and were compared with usual care participants. Vital status was followed up to 14.5 years. The smoking intervention program consisted of a 10-week smoking cessation program that included a strong physician message and 12 group sessions using behavior modification and nicotine gum, plus either ipratropium or a placebo inhaler. At 5 years, 21.7% of special intervention participants had stopped smoking since study entry, compared with 5.4% of usual care participants. Smoking intervention participants had smaller declines in FEV-1 than usual care participants. Men who quit at the beginning of the study had an FEV-1 rate of decline of 30.2 mL/year, whereas women who quit declined at 21.5 mL/year. Men continuing to smoke throughout declined by 66.1 mL/year, and women continuing to smoke declined by 54.2 mL/year. More importantly, all-cause mortality was significantly lower in the special intervention group than in the usual care group (8.83 per 1000 person-years vs. 10.38 per 1000 person-years; p=0.03) [29]. It has been shown that repeated attempts to quit smoking, even with subsequent relapses, can prevent loss of lung function, especially in patients with mild COPD [30], and prolonged abstinence is also associated to a reduction in pulmonary symptoms [31]. If a smoker with advanced COPD smoking, he/she will not recover lost lung function, but the subsequent rate of decline is likely to revert towards normal [32]. Smoking cessation at an early stage of the disease has shown to improve prognosis [28, 32-33], and there is evidence that smoking cessation at an early stage of COPD is more effective than in the later stages [34]. Smokers seem to be intrinsically more motivated to stop smoking if they realize that their respiratory complaints are caused by smoking and that they are at risk of developing COPD [35]. In a recent study, smoking cessation rates were compared between smokers with COPD and smokers with normal lung function. During follow-up, the abstinence rates were significantly higher in smokers with COPD than in smokers with normal lung function [36]. 4. Smoking Cessation Intervention Process. Tobacco dependence is a chronic condition that often requires repeated intervention to succeed [37]. Once users are dependent on tobacco, quitting is extremely difficult. Nicotine dependence resulting from tobacco use hinders efforts to sustain abstinence from tobacco for a prolonged period. Many users make multiple attempts to quit, often without the assistance that could significantly increase their chances of success. Studies have shown that a considerable number of smokers want to stop smoking, but a significant proportion of them have never tried [38]. A large proportion of all smokers are in the stage of contemplation or the stage of preparation. Most smokers go through several