How do our lungs not fill up with dust?
In: Biology
Hair in your nose filters a lot of them out, mucus secreted from the surface of your respiratory tract produces a constant flow that slowly washes out dust fell on them.
Silicosis and mesothelioma come to mind. From inhaling silica dust and asbestos fibers, respectively. Both can be deadly.
The body has several layers of defense for preventing that. Firstly, you have nasal hair that works to trap dust in the nose, and a sneezing reflex to clear it. You also have mucous membranes in the nasal passages and the throat to trap dust there, and a cough reflex to clear that part. Finally, the sides of the lower airways are covered in microscopic cilia – basically little wiggly tentacles – that pulsate upwards constantly. Together with the mucus layer that covers them this, they form a kind of sticky conveyor belt that is constantly acting to move dust out of the lungs and upwards. When it makes it to the throat, your cough reflex takes over and moves it out. This is one of the reasons that smoker’s cough is typically worse upon waking – cigarette smoke throughout the day interferes with the cilia and slows down the conveyor belt, until you go to sleep and stop smoking. So when you wake up all the nasty stuff is waiting to be coughed out.
They do. This tends to cause problems.
We have many layers of defense set up to prevent dust from getting into our lungs, but as these are evolved defenses, they aren’t perfect, nor are they effective at preventing dusts that didn’t exist in our evolutionary history.
So for typical dusts that we’re likely to experience in everyday life, our dust filters are pretty good at keeping them out of our lungs. That’s part of the point of our nasal system – hairs and mucus trap dust particles, coughs and sneezes and manual removal get rid of trapped particles.
But where this breaks down is in fine, sharp particles like volcanic ash or asbestos. These particles are small enough to bypass our natural filters, and once they get into the lungs they’re difficult to get out. Inside the lungs, they tend to damage our sensitive tissues, which causes a whole host of problems. Biggest among them is that they can cut up our lung tissue, which both reduces our lung capacity and forces our lung tissues to reproduce more often to repair the damage. This is a problem, because every cell division is an opportunity for a cellular mutation that can lead to decreased functionality or cancerous growth.
So if you work with fine dust, don’t just assume that you can tough it out. Wear an appropriate mask to protect yourself.
Nose hairs and saliva catch almost all of it. We get rid of the dust by sneezing, blowing our nose, or swallowing it.
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