Tiny, hair-like projections called cilia line the throat and nose. Cilia capture dirt and filter chemicals before they get to the lungs, transporting them back to the mouth, nose or through the digestive tract to be expelled from the body.
If cilia fail to function properly, mucus builds up in the throat and nasal passages and harmful chemicals can make their way to the lungs. Smoking damages cilia and prevents them from performing the actions necessary to filter air entering the lungs. The hacking cough experienced by smokers is due to the body trying to expel residue that cilia can no longer sweep away. Continued smoking can kill cilia and deprive the lungs of an essential filter that keeps them operating at their best.