High relative humidity and warm temperatures result in mold and mildew growth on organic surfaces. The wood substructure of the home is a food source for microbial growth. This impacts the indoor air quality of your home, as about 50% of the air in your conditioned space is from the crawl space. Mold and Mildew can be treated with an Antimicrobial, however, it will continue to return unless the relative humidity is controlled. In the home, a homeowner may notice musty odors or high humidity.