Air humidity and viruses

As the air temperature decreases, the amount of water it contains decreases. Therefore, outdoor air entering a room from outside and heated by radiators has low relative humidity. In winter, this value can drop to 20%. Optimal values are between 40-60%. Humidity directly and indirectly impacts our health; let's explore them.

 

Direct Impact of Humidity: The lower the humidity, the stronger the evaporation from the skin and mucous membranes. This means increased irritation of the eyes, nose, mouth, and respiratory tract and impaired mucociliary transport. When mucus dries out, it can irritate the mucous membranes, leading us to touch our nose, eyes, and mouth involuntarily. 

 

This increases the risk of infection, as the mucous barrier is weakened, making it easier for viruses to enter. 

 

Dryness also increases symptoms related to breathing difficulties, reduces tear production, and increases eye fatigue. If you talk a lot, your voice will tire more quickly and sound worse in dry air. Low or excessively high humidity also affects thermoregulation and sleep quality.

 

Indirect Impact of Humidity: The indirect impact of humidity lies in how it affects the circulation of dust and aerosols in the air. The lower the humidity, the more dust and allergens are present in the air and the longer they linger. Therefore, more humid air tends to be cleaner. 

 

Dry air also accumulates more electrostatic charge. Humidity affects the release of formaldehyde from walls and materials. In dry air, aerosols with viruses and bacteria stay airborne longer. 

 

The stability of viruses is minimal at 50% humidity. At 23% humidity, 70-77% of viral particles from talking or coughing remain in the air, whereas at 43% humidity, only 14% remain. This applies to both the flu and the coronavirus.

 

What to Do? Monitoring (using a hygrometer) and humidifying the air (using an ultrasonic humidifier) alleviate these symptoms. Research shows that increasing humidity to 40% relieves irritation symptoms. The optimum humidity is 40-60%; excessively high humidity is undesirable as it can cause other problems.

 

 

Indoor air humidity, air quality, and health – An overview International Journal of Hygiene and Environmental Health Volume 221, Issue 3, April 2018, Pages 376-390