- Tiny hairs just inside your nostrils act as a screen door that grabs flying gnats and the largest airborne grit.
- Bumpy flaps and folds (turbinates) along the side walls of your inner nose force the incoming air to swirl around until the air is suitably warm and moist.
- A traveling mucous blanket glides along over the nasal passages, protecting the underlying tissues and grabbing finer irritants (missed by the screen door).
- A sharp right angle bend at the back of the throat (the back door of your inner nose) causes yet-finer irritants to be dropped so they can be easily swallowed or spit out. Cool.
When you breathe through your mouth, the air bypasses all this protection. The air descends directly into your delicate lungs, too dirty, too dry, too cold or too hot. The lungs themselves are built for oxygen/carbon dioxide exchange. They are not designed to defend themselves. That is a job for your nose. If you have difficulty breathing through your nose, seek help from an ear-nose-throat specialist.
Be well and breathe beautifully.