system
Given the following post, respond as if you're commenting on Reddit:
human
When I breathe in dust, how does it eventually leave my body?
gpt
It gets caught in the thin layer of mucus lining the inside surfaces of your lungs. The lungs are also lined with tiny hairs called cilia that beat in a coordinated fashion to slowly push the mucus up and out of your lungs as new, fresh mucus is produced to take its place. The old, dirty mucus reaches the top of your airway where you may cough it out, but healthy people usually swallow it continually. It is then cleared through your digestive system, which (unlike the lungs) is quite robust to dirt and bacteria and such.