system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What happens to all the particles we inhale day after day?

I mean the physical dust, pet hair, spider and so on. Do they ever get out or they accumulate in our lungs?
gpt
Your body has layers of protection. If you breathe through your nose there are nose hairs. There are sinuses where the air is mixed and humidified. It enters your trachea and then splits into bronchi, into passages smaller and smaller. In the bronchioles the passages are lined with little hairs which sweep dust out of the air. This works unless you smoke. The tobacco smoke paralyzes this. In the morning smokers awake with smokers cough which is the little sweeping cell trying to catch up, until that first cigarette.

Your body tries to catch the junk and keep it out. There are special cells for this. They can become overwhelmed. Coal miners get silicosis and black lung. Certain forms of asbestos fibers break into short lengths which can get all the way into the alveoli raising your chance of getting mesothelioma dramatically.

It is best to not challenge the system. Breathe clean air. Use masks in dusty conditions. But our bodies try to protect us.