Mold can growth where high humidty is present. If you’re concerned about mold growth and want to determine moisture levels in your home, use a hygrometer to monitor the relative humidity (RH).
Expect to spend at least $30 to $40 for a quality hygrometer. To use it, measure in the middle of the room as well as at cold, exterior walls. In the winter in cold climates, the RH should be around 35% and not go much over 40%. To combat mold growth in the summer, the RH in the basement should not be higher than 50%. Some molds can grow at 70% to 85% RH.