Those who have asthma know the struggle all too well — and sometimes, it prevents them from running outdoors in winter. But even those of us who don’t suffer from the breathing condition find that it hurts to breathe when the air turns cold. Why is that the case? And should we push through the pain until we cross the finish line? That’s a long way to run when it hurts. But here are the answers, according to science!
First and foremost, it helps to understand what the lungs are designed to do. In a relatively short amount of time, they heat up the inhaled oxygen to 98.6 degrees Fahrenheit by increasing humidity. The process needs to be done without damaging the lung’s cells and tissues. When the heated oxygen reaches the end of its journey inside the lung’s alveoli — which connect with your blood vessels — it is then exchanged and exhaled as carbon dioxide.
Not so much for most of us, but the important part is this: the oxygen needs to be humidified. That’s why it’s so much easier to breathe in summer than it is in winter. The air is much more saturated with moisture in summer, whereas in winter it is devoid of that same moisture.
William O. Roberts, MD, writes: “The burning sensation you feel when breathing in cold air is probably due to the combination of heat and water exchange that is occurring early in the inspiration of cold, dry air. For most people, this sensation goes away after a few breaths. It is not known to cause harm in a healthy lung, but can trigger an attack of bronchospasm in someone with asthma.”
Roberts says no one should worry about frozen lungs, even in very cold weather. “Many people worry that the lung tissue will freeze in cold air, but the extensive network of blood flow through the lung tissue seems to prevent that from happening.”
Over time, he says, the human body has evolved and adapted to the harshest winter temperatures imaginable.
And there are easy ways to soothe your lungs before heading outdoors for that strenuous run. You’ll want to keep your skin covered during particularly low temps, but even when the danger of frostbite is not present, it might make sense to wrap your neck and mouth with a balaclava. While this won’t add any moisture to the air before you inhale, it will contribute to warming before the oxygen enters your lungs.