The diaphragm is a sheet of muscle that separates the chest from the abdomen. These changes also limit lung expansion. This makes the lungs less able to take in oxygen and exhale carbon dioxide. All of these changes combine to decrease lung function. The lungs also become slightly more vulnerable to infections, such as pneumonia and bronchitis.
Smoking damages the lungs and speeds age-related lung changes.
Smoking also increases the risk for chronic bronchitis , emphysema , and lung cancer .