Cigarette smoking is the most common cause of emphysema. Tobacco smoke and other pollutants are thought to cause the release of chemicals from within the lungs that damage the walls of the air sacs. This damage becomes worse over time, affecting the exchange of oxygen and carbon dioxide in the lungs. A naturally occurring substance in the lungs called alpha-1 antitrypsin may protect against this damage. People with alpha-1 antitrypsin deficiency are at an increased risk for this disease.
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