The Fieldston Science Bulletin

By: Cristina Ellis

Once again, winter is upon us. As temperatures plummet, plants and animals across the world are reacting in their own ways, and humans are no exception. Our body reacts to the cold in a myriad of ways, including shivering, goosebumps, and even a runny nose. Yes, you read that right, runny noses.

The runny nose you get because of cold air is a bodily defense mechanism. The nose protects the respiratory system in two ways: it warms air before it reaches the lungs, and it filters out harmful particles and bacteria to prevent them from penetrating deeper into the respiratory tract. To function optimally, our respiratory system needs warm, moist air.

Cold air, which is drier than warm air, can dry out mucus membranes and irritate or damage lung tissue. As a result, when exposed to cold, dry air, the nervous system responds to protect the respiratory system. It does this by causing glands in the nose to produce secretions and mucus to humidify the air before it enters our lungs. The mucus also traps dust particles, bacteria, viruses, and allergens before they reach sensitive tissue deeper in the respiratory system.

Simultaneously, blood vessels in the nasal lining expand, a process called vasodilation, bringing more blood closer to the surface to warm the inhaled air. Together, the increased mucus and blood flow protect the lungs by creating a filter and humidifier. The reaction is so effective that it can flood the nose with excess fluids, producing a runny nose.

There are several ways we can protect our respiratory system from cold, dry air, including wearing a scarf to reduce exposure and trap warmth around the nostrils, using saline spray to keep the nasal passages moist, and using a humidifier to create humid indoor environments and ease nasal irritation. You can also warm your nose when you come inside from the cold by rubbing your hands together and breathing into cupped hands and/or inhaling some steam from a hot drink.

This winter, when you go for a long walk, you might notice that you develop a runny nose. Have no fear, this is just a normal part of your body’s reactions to the cold.

Sources:

Cover Image: Adobe Stock

Why Does Your Nose Run When It’s Cold?

Quick Dose: Why Does the Cold Weather Make My Nose Run? | Northwestern Medicine

Why Does Your Nose Run When It’s Cold Outside? | Chilly Nose Secrets