Chronic obstructive pulmonary disease (COPD) is characterized both by lung disease, in small- airway inflammation, and peribronchiolar fibrosis. Lung disease results in the airway obstruction that is caused by chronic bronchitis, emphysema, or both. COPD sufferers may have difficulty breathing in addition to coughing and wheezing. The primary cause of COPD is irreversible airway obstruction brought on by smoking. Some other risk factors that can contribute to or exacerbate COPD are environmental pollutants, alpha-1 antitrypsin, asthma, and periodontal disease.