Clean your house regularly, particularly the kitchen and bathroom, to prevent the growth of mold in moist areas. Fix leaky plumbing. Control temperature and humidity. Central air conditioning is best. Use a dehumidifier to keep the relative humidity at 35-50%. Use a simple humidity gauge to regularly measure the humidity level. Increase ventilation. While showering or using the dishwasher, use an exhaust fan to remove water vapor from the air. Thoroughly clean or remove water-damaged carpet or upholstered furniture. Last update 06-22-2007.