system
Given the following post, respond as if you're commenting on Reddit:
human
How does tar from smoking get out of your lungs?

I’ve quit smoking.  For the first while, my nose was runny for like a month.  I think that was because my cilia came back to life.  However, now…usually once a day…usually in the morning, I seem to be blowing my nose and black/brownish phlegm comes out.  Is that tar?  I thought it would come up from coughing.
gpt
The cilia in your lungs slowly sweep up gunk and tar (we actually call clearing out the lungs via various techniques the “pulmonary toilet”). When they sweep things up it usually goes up and then swallowed into the esophagus. 

Now, if you were sleeping on your back all night that gunk could make its way up into the nasal cavity where it would then be blown out. 

Congratulations on quitting smoking. Keep it up! This will be one of the best decisions you will ever make in your life to improve your health. Not only does it help the lungs, it also helps just about every other part of the body too.