Why does the nose produce boogers?

Your nose is the ultimate lean, green, booger producing machine. Your nose makes mucus to prevent dust and pollen from traveling to your lungs. Some mucus is swallowed (about a quart a day) and some stays nestled in your nose. When you breathe dry air into your nose, that mucus is dried and becomes a booger. read more

The tissue of the mucus membranes starts leaking fluid, and your nose begins to run. Drinking milk may also make some people produce more mucus. Kao says that's due to gustatory rhinitis, a reflex reaction that's triggered by eating. Gustatory rhinitis is also why your nose runs when you eat hot peppers. read more

Sometimes the mucus has trouble fully exiting the nostrils. It begins to dry out, and may become clumped together. Additional dust and other debris join forces with the drying mucus and — voila — a booger is formed [source: Kids Health]. Boogers form more frequently when you have the common cold or a bout with allergies. read more