As winter arrives, many people get colds, flu, and other respiratory infections. But why do we get sick more often during these colder months? Research helps explain how cold weather can weaken our immune defenses.
Problem #1: Cold Air
Our nose is the primary entry point for respiratory viruses and bacteria. When viruses try to invade our bodies, the cells in our nasal passages are ready to take action. They produce extracellular vesicles (EVs), which are small structures that help defend against viruses.
These EVs act as decoys, attracting viruses and preventing them from attaching to our actual cells. This response helps neutralize threats before they can multiply and make us sick. A study shows that during an attack, the nose can increase EV production by 160%.
However, cold air can compromise this immune response. Research indicates that when participants were exposed to 15 minutes of 40°F (4.4°C), the effectiveness of their nasal defenses dropped significantly. Cold air can reduce the number of EVs involved in immune defense by nearly 42%, meaning fewer viruses are captured.
Problem #2: Dry Air
Dry Air Weakens Our Nasal Defenses
Dry air is another factor that weakens our nasal defenses and activates respiratory viruses, especially in winter. The membranes lining our nasal passages typically trap dust, viruses, and bacteria, preventing them from reaching the lungs. But when we are exposed to dry winter air, these membranes can become dry, impairing their ability to filter out harmful pathogens.
Dry Air Increases Virus Transmission
Additionally, dry air increases the activity of viruses, including coronaviruses. Research shows that low humidity levels allow these viruses to survive in the air for longer periods.
A study found that at 25% relative humidity, coronaviruses remained infectious in the air twice as long as they did at higher humidity levels (40% and 60%). When viruses linger in the air longer, the risk of transmission increases.
What Can We Do to Reduce Sickness in Winter?
Air purifiers equipped with HEPA filters are specifically designed to capture small particles, including respiratory viruses, allergens, and pollutants. By reducing the number of airborne viruses, your nasal defenses can capture fewer pathogens with extracellular vesicles (EVs). When cold and dry air weaken these defenses, an air purifier acts as an external nasal filter, helping to trap harmful pathogens before they can enter your body.
By understanding how cold weather impacts our immune defenses, we can take proactive steps to stay healthy during winter. Maintaining comfortable indoor humidity and temperature levels and using an air purifier are essential for minimizing the spread of airborne viruses and protecting our health.
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