EVERYDAY HEALTH - The Link Between Smoking and COPD - COPD Center, Nov 07, 2011

"Chronic obstructive pulmonary disease (COPD) is the fourth-leading cause of death in the United States, and the number of people with COPD is increasing. More than 12 million people are diagnosed with COPD; an additional 12 million may have the condition and not know it, according to the National Institutes of Health. And as many as 9 out of 10 cases of COPD can be traced directly back to one culprit: smoking."