Chronic obstructive pulmonary disease is also known as COPD. COPD is actually two related diseases: chronic bronchitis and emphysema. In both diseases, there is chronic obstruction of the flow of air through the airways and out of the lungs. The obstruction is permanent and gets progressively worse over time. While COPD is actually two diseases, patients will have characteristics of both; this is why a single term is used to describe both conditions.

A study, published in the online journal, Thorax (October, 2006), states that one in four smokers will develop COPD. This is a higher figure than originally thought. In Denmark, 8,000 patients between the ages of 30 and 60 were monitored for 25 years. This was part of the Copenhagen City Heart Study.

Over the 25 year course of the study, 100% of the male and 90% of the female non-smokers had normal lung function. Of the smokers, only 70% of the women and 60% of the men had healthy lungs at the end of the 25 years. About 25% of the subjects developed moderate or severe COPD over the 25 years. Regular smokers were six times more likely to develop COPD than non-smokers.

During the 25 years of the study, 2900 of the subjects died, 109 of those deaths attributable to COPD. All but two of the COPD deaths were smokers. The good news is that the risk for COPD dropped drastically for those who quit smoking at the beginning of the study.