About 50-90% of people in the cold season experience a runny nose. People with asthma, eczema, and hay fever are more likely to experience this condition, according to experts.
The job of the nose is to make the inhaled air warm and moist so that when it enters the lungs it does not irritate them. When air is inhaled through the nose at temperatures below freezing, the air at the back of the nose usually has a temperature of around 26°C, but can reach as high as 30°C. The air humidity in this part is usually around 100%, no matter how cold the air is. we breathe in. How does this happen? Cold, dry air stimulates the nerve endings inside the nose, which send a message to the brain. The brain responds to this impulse by increasing blood flow to the nose, and the dilated blood vessels heat the air passing through them. Then there is an increase in secretions through the mucous glands to provide moisture to the passing air. Cold, dry air also stimulates immune system cells (called “mast cells”) in the nose. These cells cause fluid in the nose to increase to make the air more humid. It is estimated that only for this function a person can lose up to 300-400 ml of fluid daily. Heat and water loss are closely related: heating the air in the nasal cavity means that the mucous membrane becomes colder than body temperature; at the same time, the water evaporates to make the air humid. Evaporation of water, which requires a lot of heat, takes heat away from the nose, making it cooler. In response, blood flow to the nose increases even more, since the task of heating the air that is inhaled takes precedence over heat loss. So it’s a difficult process to achieve the right amount of heat and moisture. When the compensation mechanism is overactive, more moisture than is needed to humidify that cold, dry air will appear as droplets. Mast cells tend to be more sensitive in people with asthma and allergies, and blood vessels change more reactively in those who are sensitive to environmental stimuli and temperature changes. Thus, nasal congestion and even sneezing can be caused by cold air.