Here’s a little snippet of information that I’ve imparted to many a person on the hill, who have all said “Oh – I’ve always wondered about that…” – which made me decide to share it with the Internet at large.
I wondered for years why going out in the cold gives people the sniffles and then one day I met an Ear, Nose and Throat surgeon and somehow remembered to ask him. This is what I understood of what he told me:
Taking freezing cold air into the delicate tissues of the lungs isn’t a great idea so there are structures in your sinuses which swell with nice warm blood to pre-warm it. They swell to create more surface area to get as much contact with the air as possible.
Which is great for the lungs but not so much fun for the swollen tissues doing the warming. So to protect themselves they exude more mucus. That extra mucus is what gives you the sniffles.
When you finally go in to a warm room and your nose starts to run like mad, that is because those tissues are sensing that their duty is done and they contract, suddenly leaving far less surface area for all the mucus. Imagine blowing up a balloon and painting a thin layer of honey onto it. Then let the balloon deflate; most of the honey would run off as the balloon contracted.
So, more than you ever wanted to know about sniffly noses!