According to Owens Comfort Systems, the best setting for a home humidifier is between 30 and 40 percent. This is the ideal setting as the risk of health-endangering conditions, such as bacteria and viruses, is significantly lowered.
Humidity levels below 30 percent are considered dangerous for people and other household contents. Humidity above 75 percent can encourage the growth of mold and bacteria. You should set your humidifier at an ideal range for indoor humidity. This is between 40 to 60 percent.