Breathing in dry air is basically a high negative stress on the human body. The organ systems such as nose, mouth, throat, mucous membranes and bronchi strive for one hundred percent humidity. During inhalation, the air is heated to body temperature and completely saturated with water vapour. Especially in the transitional and winter seasons, people are stressed by the dryness of the air they breathe. In this case, the human body can quickly reach its limits, as the respiratory tract has to provide every percent of humidity that is not present in the room air itself.
Microbes and viruses
The survival time of microbes and viruses is also strongly dependent on the humidity. Dry air is a perfect carrier. At a humidity of less than 40 %, viruses are in a so-called dormant phase. The droplets release water as the humidity decreases and become smaller. The flu viruses are trapped in the dried droplets without being deactivated - but they retain their ability to infect. When the dry air is inhaled, it is gradually rewetted in the respiratory organs. This allows a large proportion of the viruses to penetrate deep into the human lungs and escape the natural biofilters. The trapped viruses and microbes are reactivated by the increasing humidity and can trigger an infection [see (Dr. Walter Hugentobler, 2017) and (Eriko Kudo et al., 2019)].
