Volatile organic gases (VOCs)are generated by the mold as the mold grows. The musty odor is the gase. Some people are allergic to the VOCs. In addition, the spores released by some the molds make people ill. The Vocs and the spores move throughout your home. The 48 hours is time you have to dry the materials in your home before the mold has much growth. The high humidity in the basement moves thourghout your homes and will cause mold growth whereever the relative humidity is +70%.