At the Chair of Building and Indoor Climate Technology, E.ON Energy Research Centre, RWTH Aachen University, a comprehensive study in German was published at the end of February 2021 on the topic of "The influence of air humidity on people and their health": https://publications.rwth-aachen.de/record/811532/files/811532.pdf
In summary, the study is about determining the optimum air humidity for humans in closed rooms.
WE HUMIDIFY THE AIR.
