Asthma is a chronic disease that affects how air is carried in and out of the lungs. People with asthma may react strongly to things they are allergic to, causing less air to travel to the lungs. COPD (chronic obstructive pulmonary disease) is a chronic inflammatory lung disease that causes obstructed airflow from the lungs, making it hard for a person to breathe. The two main types of COPD are chronic bronchitis and emphysema.