[titzer]

Something that I noticed recently is that if speed isn't a major goal, breathing through the nose is a lot more healthy. In through the nose, out through the nose.

First, it filters incoming air of particulates like dust and pollen--gross stuff you don't want in your lungs. Over an hour of running, you can easily breathe 600L of air, in a city, that's a lot of pollution.

Second, it calms you. Breathing through the nose is a meditation exercise that automatically calms your mind.

Third, it reduces dehydration. Most of the water not lost through sweat and through the skin is lost through evaporation from the mouth. Through the nose instead, the same filtration system that keeps dust particles out serves as a condensation site for some of the moisture that would otherwise exit from your lungs.

Problem is, you can't run super fast breathing through your nose because of the limitation in breath volume from the restricted pathway. The article is right; IMO you should not run faster than what you can manage through nose breathing alone.