Various studies have shown that the risk of infection is significantly minimised when we humans spend time in areas with a humidity of 40 to 60 % (at a room temperature of +21 °C).
Most viruses and/or microbes are inactive in this range and pose a significantly lower risk of infection.
People who are allergic to dust can benefit from the humidity because the particles that are in the air accumulate with the water particles, which become heavier and fall to the floor as a result. The same is true for viruses. Those that survive are much less likely to stay in the breathing zone, as they also fall to the ground.