Asthma, AZ muh, is a chronic lung disease characterized by periods of breathlessness, wheezing, and coughing. People with asthma suffer from chronic inflammation of the bronchi (airways to the lungs). The inflamed airways react to irritation by swelling, constricting, and filling with mucus. These changes obstruct airflow (the ability to force air in and out of the lungs). An asthmatic person may feel short of breath or experience difficulty in breathing. Severe attacks may involve spasms (sudden constriction) of the airways, causing sufferers to gasp for air and feel that they are suffocating. These attacks require immediate medical attention and can cause death.