Mold loves humidity. Did you know humidity levels should be between 30 and 60 percent in order to prevent the spread of mold spores? A good way to make sure humidity stays within those levelsis to use a humidifier that will automaticallyadjust to humidity levels present. Good air conditioning systems can also help by adding extra humidity to the air. If you use an air conditioner you'll still want to use a humidity reader to make sure the levels aren't too high or low.