The immune system is the biological defense system that protects the body against pathogenic microorganisms such as viruses, bacteria and fungi, fine dust and other aggressive substances. Its first line of defense is the mechanical barriers of the skin and the mucus membranes of the airways. The airways with their mucus membranes protect the body by removing pathogens as quickly as possible with the help of the sticky mucus to which they adhere and which conveys them against the larynx like a rolling carpet. Mucus and cilia are part of a sophisticated self-cleaning mechanism. The cilia move back and forth, like grass in the wind. This movement transports the mucous and all unwanted invaders towards the larynx, where they can be coughed out or swallowed after clearing the throat. In the stomach, they are destroyed by gastric acids.

If the air is too dry, the secretion becomes sticky and impedes the movement of the cilia. With a good level of humidity in the air and properly functioning mucous membranes, the pathogens can be eliminated from the respiratory tract via the mucous membranes and rendered harmless within between 5 and 30 minutes. However, the longer they stay in the body, the greater the contagion risk becomes. "At workstations with air humidification, the complaints regarding dry air reduce by one third to 35 percent" a current study at the Fraunhofer Institute for Industrial Engineering has determined (Jurecic, Rief).

Larger airborne particles

The water vapor in the air links all surfaces of the room, including the airborne particles, through condensation. The airborne particles become “sticky” through the adsorption of water. The particles therefore increasingly stick to the surfaces, become heavier, are deposited more quickly and can no longer be breathed in. The air becomes cleaner. Ultimately, larger particles can no longer penetrate so far into the respiratory tract and are transported away more quickly. A video at tinyurl.com/ha82vnq shows this interconnection clearly. In general, a relative air humidity of between 40 and 60% is recommended. A study proves that among asthma sufferers, air humidification contributes to alleviation of the symptoms (Strauss).