The nasal cavity has two functions. one is to

The mucosa secretes mucus. Found in the naval cavity, it contains bipolar neurons, also known as olfactory cells, which are very important for being able to have a sense of smell. The dendrites of these olfactory cells reach out of the surface of the mucosa. The axons of these cells are actually bundled together. There are about 20 of these bundled axons, and collectively they are known as the olfactory nerve or the first cranial nerve.

Anatomically, it passes through the cribriform plate found in the ethmoid bone, having synapse with the olfactory bulb, an essential neurological connection that allows the sensation of smell to work. The first cranial nerve can actually be tested by closing one nostril and holding up a smelly object to the other opened nostril to see if the sense of smell is still working. The nasal mucosa is also continuous the sinuses, which not only help warm and moisten the inhaled air, but also provide resonance to the voice and give the face more shape.

d they all are treatable but they never completely go away