What is the lowest permissible temperature for winter running?
How to breathe properly when running in the severe winter frost?
Master of Sports of International class in track and field athletics, winner of the Zurich marathon, participant of the Beijing 2008 Summer Olympics, multiple European Cup and Russian championships medalist, coach of the school “I Love Running”
I'm of the opinion that extreme running and comfortable run are two different types of motor activity. If you don't like extreme sports and don't want to risk your health anyway, I would recommend you to train outside when the temperature is not lower than 20 degrees C.
It's convenient to use a so called "baff" covering your chin, neck and some areas of face during running in the frost. The air going through the fabric gets warmer and becomes less dangerous for mucous membrane of the upper respiratory airways. At the very beginning of training you can inhale through the nose and exhale through the mouth. When you warm up your body a little you can continue to breathe through the mouth.