I rode to work today, 5 miles at -15F. I wear a neoprene face mask but cut out the mouth hole or I get way to much moisture build up. I have been riding this way for the last three years and I have had discomfort but not lasting bad effects from the the cold air. As many have said, life goes on year round in the north and we survive. I have never heard of any one dying from breathing the cold air. It is exposure that is the danger.