You need a good relative humidity
If you want optimal indoor environment quality you need a good relative humidity. This research paper explains what humidity is and what effects it has.
Humidity can have a direct impact on the health, comfort, well-being and performance. The results of various studies can be applied more broadly as infectious organisms are found everywhere. The need of controlling humidity is essential in all buildings such as schools, offices, homes, hospitals, etc. Humidity levels also key for building constructions, materials and equipment in buildings. In the broader picture humidity is very important for the global climate.
Humidity is the amount of water vapour in the air, and it can be measured in absolute or relative terms. The target level of humidity in buildings is between 30-60%. Here you can read and understand why and what variables affect the related humidity level. This is a well written research paper which is easy to understand and written by Swegon.