Chronic Obstructive Pulmonary Disease (COPD) is a group of lung diseases (including emphysema and chronic bronchitis) that block airflow in the lungs. This makes it increasingly difficult to breathe. Many of the symptoms of COPD are similar to asthma symptoms. Although COPD is the leading cause of death and illness worldwide, it is often preventable. That is because long-term cigarette smoking is the primary cause of this life-threatening disease. Additionally, smokers are particularly likely to suffer from a combination of both asthma and COPD.It is important to distinguish between asthma, COPD or a combination of the two, as the treatment approach will differ. An allergist / immunologist has specialized training and experience to accurately diagnose these conditions.