Asthma is a chronic respiratory condition characterized by attacks of wheezing and difficulty in breathing. The cause of asthma attacks is partial obstruction of bronchi and bronchioles resulting from the contraction or spasm of the muscles in the bronchial walls. Attacks may be mild or severe and may last anywhere from a few minutes to a few days. Asthma may develop at any age, although many children with asthma outgrow the condition as they get older and the bronchial passages widen. Asthma may be hereditary.The two major types of asthma are extrinsic and intrinsic. Extrinsic asthma is the most common type and is typically triggered by a hypersensitivity to irritants or allergens, such as dust, pollen, feathers, animal dander, molds, smoke, extremely cold or dry air, and air pollutants. (Allergens are substances that cause allergic reactions, such as asthma, in some people.) For some asthmatics, drugs, food allergies, and exercise may induce an attack.

Intrinsic asthma is caused by factors such as stress or as a result of frequent respiratory tract infections. This form of asthma is less common than extrinsic asthma, but its symptoms are similar.

There is no cure for asthma, but there are preventive measures and treatments that help reduce the severity and length of an attack. One form of prevention is immunotherapy in which the asthmatic is desensitized through injections of weakened allergens .Medications, such as corticosteroid drugs, reduce inflammation and serve as a primary intervention for many asthmatics.

Bronchodilator drugs (medicines that open the bronchioles) are used routinely by asthmatics when an asthma attack occurs. These drugs are breathed in through an inhaler and usually restore normal breathing in several minutes.

One way to anticipate an impending attack or to determine the severity of an actual attack is by means of a peak-flow meter, a small hand-held de­vice available at drug stores that measures airflow. Peak airflow will go down hours, and sometimes even a day or two, before an attack, so the meter can serve as an early warning system. During an attack, it provides an objective way to determine how much the air passages in the lungs narrow.

Exercise-induced asthma is common among asthmatics. Symptoms include a coughing attack and tightness in the chest during or shortly after exercise. It appears to be most common when the asthmatic exercises in cold, dry air. Still, physical activity remains an integral part of wellness for individuals with exercise-induced asthma. Improvements in fitness and health status occur in asthmatics who exercise. An added benefit is that for many asthmatics exercise is accompanied by a decrease in the frequency and severity of exercise-induced attacks.