In the lungs, oxygen enters the blood in exchange for its waste product, carbon dioxide, which is exhaled. As air flows to the lungs, tiny bands of muscle encircle the airways, and their job is to tighten up to keep out irritants - say, smoke from a burning house, dust or pollen. The inner lining of the airways is coated with a thin layer of mucus that traps any irritants. And tiny whiplike structures called cilia move any trapped irritants, along with some mucus, up toward the mouth and nose where they are coughed and sneezed out or swallowed. No one knows why for sure.
Asthmatics are particularly sensitive to infection, weather, exercise, irritants and allergens.
For Jordan, cigarette smoke is a surefire trigger. At the same time, the airway lining begins to swell, shrinking the passageway even more. The wheezing sound is air rattling through narrow pipes. Then, the already narrow airways fill with mucus, leaving asthmatics battling for every breath. She has asthma, too.