as emphysema and chronic bronchitis, is a condition that makes it difficult to breathe and gets worse and worse over time. In addition to shortness of breath, COPD can cause severe coughing, excess mucus production, wheezing, and chest tightness. The disease affects more than twenty-four million Americans.35 Smoking is far and away the leading cause of COPD, but other factors can contribute, such as prolonged exposure to air pollution.
