system
Given the following post, respond as if you're commenting on Reddit:
human
How do lungs clean themselves?

I'm mostly interested in understanding the mechanism for this because it's one of the only organs which is directly exposed to the environment. Thank you, in advance.
gpt
Most of the larger particles are caught by nasal hairs, then the smaller particles that evade the hair are caught in the mucus produced in the respiratory passages (up till bronchi). Further ahead in the respiratory bronchioles and alveoli (the part where actual gaseous exchange takes place) there are no mucus producing cells, and the even more smaller particles such as bacteria that do manage to reach there are eaten up by alveolar macrophages, which are basically your germ eating cells.