PREVIEWAsthma is an inflammatory disease of the airways to the lungs. It makes breathing difficult and can make some physical activities challenging or even impossible.According to the Centers for Disease Control and Prevention (CDC), about 25 million AmericansTrusted Source have asthma. It's the most common chronic condition among American children: 1 child out of every 12Trusted Source has asthma.To understand asthma, it's necessary to understand a little about what happens when you breathe. Normally, with every breath you take, air goes through your nose or mouth, down into your throat, and into your airways, eventually making it to your lungs.There are lots of small air passages in your lungs that help deliver oxygen from the air into your bloodstream.Asthma symptoms occur when the lining of your airways swells and the muscles around them tighten. Mucus then fills the airways, further reducing the amount of air that can pass through.These conditions can then bring on an asthma "attack," which is the coughing and tightness in the chest that's typical of asthma. Oder a copy now!