This document provides information about asthma, including its definition, causes, diagnosis, and treatment. It defines asthma as a chronic lung disease that causes narrowing of the airways. Environmental factors that can trigger asthma are discussed such as pollution, tobacco smoke, allergens, and certain lifestyle factors. Diagnosis involves a medical history, physical exam, and lung function tests. Treatment varies depending on asthma severity and can include medications, immunotherapy, and following an asthma action plan.