Did you know that approximately 50-90 percent of people experience a runny nose when it’s cold outside? There are a few names for this occurrence: “skier nose” and “cold-induced rhinitis.” Those with eczema, asthma and hay fever tend to have it more.
A Key Job of Your Nose
When we think of the function of our nose you naturally will think of smell. The nose has another critical job, however-ensuring that the air you breathe in is warm and moist so that when it reaches your lungs it doesn’t irritate the cells.
When you inhale air through the nose at subfreezing temps, the air in the back of the nose is typically about 26°C but can reach as high as 30°C. The air’s humidity at the back of the nose is typically around 100%, regardless of how cold the air is that you’re breathing in.
This shows the nose is highly effective at making sure the air we breathe turns sufficiently warm and wet prior to reaching the lungs.
How Does It Do It?
Dry, cold air stimulates the nerves inside your nose, which transmit a message through your nerves to your brain. Your brain then reacts to this impulse by expanding the blood flow to the nose. The opened blood vessels warm the air that’s passing over them. Then, the nose is prompted to manufacture additional secretions via the mucous glands to provide the moisture necessary to humidify the air that’s coming through.
The chilly, dry air also triggers immune system cells. These are referred to as “mast cells” inside your nose. These cells stimulate the production of additional liquid in your nose to make the air moister. Did you know that you can lose up to 300-400mL of fluid each day through your nose as it performs this function?
The loss of heat and water are closely related. When the air in the nasal cavities is heated that means the lining of the nasal cavity (mucosa) becomes cooler than the internal body temperature. Simultaneously, water evaporates to moisten the air. Water evaporation, which requires significant amounts of heat, removes heat from the nose, thereby making it cooler.
As a response, the blood flow to the nose further increases as the task of warming the air that’s breathed in takes priority over heat loss from the nose. So it can be a challenging balancing act to attain the proper amount of heat and moisture that the nose loses.
When the compensatory process is slightly overactive, moisture that exceeds what’s required to humidify cold, dry air will drip from the nostrils. Mast cells are typically more sensitive in those with asthma and allergies, and blood vessel changes are more reactive in people who have sensitivity to environmental irritants and changes in temperature. So cold air can trigger nasal congestion and sneezing.
‘Tissue Treatment’
The easiest way to address cold-induced rhinitis is to just carry some tissues with you when you’ll be out in the cold.
Here is some additional information about cold weather increasing respiratory symptoms.