The fungi that cause shower mold play a helpful role outside, and are commonly found in the air. Given a happy home in the hot, humid locale of your shower or bath and fostered by soap residue, dirt, and oils from your skin, these molds can quickly become quite the unwelcomed houseguest. Molds begin forming colonies as little as 24-48 hours after finding a hospitable damp surface, and once spore-making commences, can spread like wildfire. Fortunately, this common home problem is one of the easiest to prevent and cure — so long as you don’t let it get out of hand.