Humidity enters an ice rink with incoming ventilation air, the opening of doors, from the use of showers, and through the normal respiration of the people within the building.
If your facility is in a cold environment such as Winnipeg, MB, Canada, the incoming air can easily be 0°F and 50% relative humidity during a typical winter day. If this entering cold air is warmed up to 40°, the humidity will now fall to less than 20% because warm air is able to hold more moisture. This lower humidity level poses little problem to the proper operation of the facility.