BREATHE THROUGH YOUR NOSE - PART ONE.
Do it for the filter.
Hairs line the entire nasal cavity. The hairs help push the foreign matter from the air back where it came from. The cilia, tiny hair-like projections, help do this further down the respiratory tract.
Mucus traps anything that may have slipped by. This gives the hair and cilia time to shuttle out the rest of the crap. Any germs and pathogens that may have come along for the ride get dealt with.
Clean air means increased fuel efficiency. Nasal breathing improves the quality of air to your engine. Your body doesn't have to work as hard, so it burns less energy.