Emphysema and chronic bronchitis, generally occur together. As a result the surface area necessary to exchange oxygen and carbon dioxide becomes inadaequate, and patients become more and more short of breath. As the inflammation progresses, the bronchi, fill with mucus and grow norrower, hindering the flow of air. This results in a chronic cough, as the body attempts to rid itself of the excess mucus that is irritating the lungs. This mucus is also know as phlegm or sputom.
Cigarette smoking is by far the most common cause of both emphysema and chronic bronchitis.
A smoker is 10 times more likely to die of emphysema than a non-smoker. Other causes like environmental pollution and occupational exposures have also been implicated in the development of emphysema. Don't wait until its obvious. An introduction to the mechanisms of disease. Referenced FDA Consumer Magazine March-April 1999.