Air comes through your mouth, air also comes through your nose! Is there really a difference?
The volume of your nose and all the sinus cavities, stretches up above your eyes inside your head, are almost as big as your fist!! This unique structure, slows down the air, filters it, humidifies and conditions it so by the time it gets into your lungs, your lungs can absorb all that oxygen so much better and easier (20% more oxygen as opposed to breathing through the mouth). When you breathe through your mouth, you’re giving out way too much co2 which might cause restrictions in circulation.
The nose also produces nitric oxide, which is a vasodilator (yes, same stuff meatheads take pre-workout to get a better “pump”) that plays a main role in oxygen delivery and also helps fight off viruses, bacteria and other pathogens!
So, your nose is really the 1st line of defense!