Why does breathing through the mouth dry the windpipe and cause sore throat, but not through the nose?
It isn’t the mucus in your nose that warms and humidifies the air you breath, it is the blood capillaries that are present in your nose. There are a ton of capillaries in your nose, and they all have blood running through them. Blood is warm, and so the air that passes through your nasal passages get warmed and humidified by the capillaries. The mucus is there to protect your airways from inhaling bacteria and other foreign particles. If you breath through your mouth, your airways (windpipe) will dry out because your mouth does not actively warm and humidify the air.
