Debris from cockroaches and dust mites, fungus spores, pet dander, noxious chemicals. . . . These are a few of the things that can make the typical home a dangerous place for people with asthma. Molecules from these agents can trigger unnecessary immune responses in a susceptible person, producing breathlessness, wheezing, and coughing. Some people outgrow asthma after childhood, some first develop it in adulthood, and others must cope with it all their lives. Over time, inflammation can reshape a person's airways and leave the lungs permanently impaired.