"Cigarette smoking is the primary cause of , and smoking cessation is the most effective means of stopping the progression of chronic obstructive pulmonary disease. Worldwide, approximately a billion people smoke cigarettes and 80% reside in low-income and middle-income countries. Though in the United States there has been a substantial decline in cigarette smoking since 1964, when the Surgeon General's report first reviewed smoking, smoking remains widespread in the United States today (about 23% of the population in 2001). Nicotine is addictive, but there are now effective drugs and behavioral interventions to assist people to overcome the addiction. Available evidence shows that smoking cessation can be helped with counseling, nicotine replacement, and bupropion. Less-studied interventions, including hypnosis, acupuncture, aversive therapy, exercise, , s, , s, and , have assisted some people in smoking cessation, but none of those interventions has strong research evidence of efficacy. To promote smoking cessation, physicians should discuss with their smoking patients “relevance, risk, rewards, roadblocks, and repetition,” and with patients who are willing to attempt to quit, physicians should use the 5-step system of “ask, advise, assess, assist, and arrange.”"