system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What keeps water from getting in, or collecting in, our lungs during heavy fog or mist?
gpt
>What keeps water from getting in, or collecting in, our lungs during heavy fog or mist?

Nothing.  Water does get in.  It coats the entire surface of the lungs.  However, lungs are always coated with moisture, so it's no big deal.  The moisture traps dirt and dust.  The surface of the lungs is covered with tiny hair-like structures called cilia.  The cilia move in waves and sweep excess moisture, dust, dirt, and foreign contaminants out of the lungs.  It all gets swept up into the throat to be swallowed and digested.