Normally, with every breath you take, air goes through your nose and down into your throat, 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 these air passages swell and the muscles around them tighten. Mucus then fills the airways, further reducing the amount of air that can pass through. This can bring on an asthma attack.
