Nose filters, and adjusts air temperature and humidity - it's not just a passive in/out hole. Evaporation is a big factor in both controlling temperature and w

Nose filters, and adjusts air temperature and humidity - it's not just a passive in/out hole. Evaporation is a big factor in both controlling temperature and water retention/loss ( that's why dogs pant in hot weather ). Remember the surface of your lungs are topologically on the outside - they are large and wet and are sensitive to both physical dust etc as well as potential infection. The nose design has to find the best balance across all these factors ( as well as being important in the sense of smell ).