Chronic obstructive pulmonary disease (COPD), is a progressive disease that makes it difficult to breathe.  COPD tends to gets worse over time.

COPD is the 4th leading cause of death in the U.S., and the economic burden of COPD in the U.S. in 2007 was $42.6 billion in health care costs and lost productivity.

COPD is caused by noxious particles or gas, most commonly from tobacco smoking, which triggers an abnormal inflammatory response in the lung. The inflammatory response in the larger airways is known as chronic bronchitis, which can be diagnosed clinically, usually accompanied by regularly coughing up sputum.

In the alveoli, the inflammatory response causes destruction of the tissues of the lung, a process known as emphysema.

In COPD air is restricted from flowing in and out of the airways because of one or more of the following:

• The airways and air sacs lose their elastic quality.

• The walls between many of the air sacs are destroyed.

• The walls of the airways become thick and inflamed.

• The airways make more mucus than usual and they become clogged.

The primary risk factor for COPD is chronic tobacco smoking. In the United States, 80 to 90% of cases of COPD are due to smoking. Exposure to cigarette smoke is measured in pack-years, the average number of packages of cigarettes smoked daily multiplied by the number of years of smoking.

The likelihood of developing COPD increases with age and cumulative smoke exposure, and almost all life-long smokers will develop COPD, provided that smoking-related, extra pulmonary diseases (cardiovascular, diabetes, cancer) do not claim their lives beforehand.