Chronic obstructive pulmonary disease (COPD) is actually a group of diseases that includes chronic bronchitis and emphysema. The common characteristic is obstruction to airflow out of the lungs. Other symptoms include shortness of breath, chronic cough, and mucus production with cough and wheezing.
In the U.S., more than 85% of COPD is due to smoking tobacco. The remaining 15% is due to such factors as previous serious lung infections, inhalation of fume-laden air that damages the lungs or genetic abnormalities. It is estimated that more than 24 million people in the U.S. have COPD.
— Source: National Lung Health Education Program