system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why can lungs not heal themselves from silicosis?

Why are we told that after we quit smoking our lungs are "self-cleaning" and will heal after the pollutant is gone, but told that for silicosis the damage cannot be reversed?
gpt
Silicosis damage is caused by breathing in dusted crystalline silica. Basically, tiny shards of glass. This stuff shreds your lung tissue and your lungs heal by scarring.

Most contaminants we get exposed to like this don’t actually cause that kind of physical damage. They just stick to the interior of the lung, blocking oxygen from being absorbed and introducing chemically dangerous things to your body. But once exposure has stopped, filaments in the lung called cilia push the contaminants out.

Silica shreds the tissue and leaves scarring that prevents lung function. That scarring doesn’t go away, even when the silica is long gone.