That musty smell in your house is not from age. Living, breeding microorganisms are the problem. Micro-organisms emit gasses that create that musty smell indoors. They make themselves at home where there is an organic food source, little air movement and light, and wet, humid conditions. To prevent that musty smell, be sure to treat moist, damp areas with an anti-microbial treatment — like a 10 percent bleach solution.