MODEL RELEASED. Asthmatic boy using his inhaler. Asthma is a condition in which the small airways (bronchioles) in the lungs constrict, making it difficult to breathe. This causes wheezing, coughing and breathlessness. The inhaler is an aerosol pump that releases bronchodilator drugs, which widen the airways. Asthma attacks can be brought on by exercise, allergic reactions and cold weather. Asthma usually develops during childhood and improves as the patient matures.