The nasal cavities earn an “A+” for their efforts to filter, moisten, warm and otherwise prep the incoming air as it travels toward your lungs. All this processing occurs in a split-second (hour after hour, day after day, year after year). Your nose is an extraordinary design with at least half a dozen clever built-in systems to protect you from illness and even death.
Your mouth, on the other hand, provides pretty much an unprotected straight shot in and down. The mouth is built for eating and kissing, NOT BREATHING. When you inhale through your mouth, the air is not slowed down for processing the way it is in your nose. Your mouth warms and moistens the air a bit but gets an “F” for filtering out airborne garbage.
There is also a tendency to breathe high in the chest when you mouth-breathe because the air rushes in and isn’t slowed by passing through the wonderful furry, sticky, bumpy, twisted maze of your nasal cavities.
If you have a deviated septum, if your allergies obstruct your nasal passages, if you have a chronic sinus irritation, then it is time to see a specialist to diagnose, correct or at least improve the situation. Every breath you take through your mouth contributes to polluted lungs and a dried out respiratory system.
Be well. Breathe beautifully.