What exactly is relative humidity?
Relative humidity is the amount of water vapour in the air and is expressed as a percentage of the total amount that can be retained for a specific temperature.
Atmospheric air always contains water vapour, the percentage of which depends on weather conditions. The higher the temperature, the more air maintains water vapour.
Ideal relative humidity levels in different situations and rooms:
The most comfortable humidity for humans: 45-65% RH
Ideal moisture for prophylactic and curative purposes: 40-55% RH
Computer and telecommunications devices: 45-60% RH
Wooden furniture and musical instruments: 40-60% RH
Libraries, art galleries and museums: 40-60% RH
Bedroom, living room: 45-65% RH