How does a breeze cause irritated nose and throat?

Question

The question popped in my head as to how a breeze (let's say one from a ventilator or ACU) can cause irritation in certain respiratory systems (e.g. nose/throat).

I haven't really found a suitable explanation by Google-ing?, so I came here to ask you.

I'm not here for an explanation that I won't understand, I'm no medical/biological expert at all, I'm just an overly curious person.

A simple, to the point explanation would do the trick for me.

PS: Just in case you're wondering how/why this question popped into my head, it's because I forgot to turn the fan off in my room before going to sleep & now I've come down with an irritated nose & sore throat.

PPS: I would've added more tags but not enough rep yet and for some reason throat and respiratory-system aren't known tags yet.

Answer 1

It does so by drying out your mucous membranes. Air moving over your face as you sleep is going to have more of a drying effect on your nose, sinuses, and throat than still air. This is especially true when the air is dry, such as in winter or when the air is from an air conditioning unit.

The reason the membranes inside your upper respiratory tract are called mucous membranes is because they secrete mucous, which serves a protective role against pathogens and airborne particles. In your mouth and throat you also have saliva, which serves a similar role. Inhaled bacteria, viruses, fungi and dust are trapped by the mucous and saliva, which is then either expelled or swallowed and digested. This is a very important part of your immune system, so if excessive drying leads to those membranes being directly exposed to air, pathogens will have an easier time invading and you will be more likely to become ill.