Ever wondered why you cough more when you quit smoking?

 
Smoking deadens the cilia in the lungs.
 These are little hairlike cells that help brush out dust
 and other residues in normal, healthy lungs. One of the
 reasons smokers have more infections is that their cilia
 are not working, so foreign matter accumulates in their
 lungs. When you quit, the cilia get back to work within
 a couple of days. The result: you start coughing up more
 phlegm and sputum. Sometimes, ex-smokers get scared by
 this and think they have a new problem. But it's not that
 at all, just another example of your body getting back to
 normal.