This is a subject that we donít like to talk about, No one does. As a professional working in basements for 25 years I have to bring it up. There is mold in basements, even if you canít see it. Sometimes you can smell it but still canít see it. In this case if your basement is not finished all that is needed is air circulation and a dehumidifier. Always use a dehumidifier in your basement, finished or unfinished. Then a good thing to do is to not close your heat ducts. A lot of people close them off and when the furnace runs the basement doesnít share in the circulation of air. Also make sure there is a return air cutout into the furnace cold air side. This gets the air off the floor and into circulation. Then install a good quality filter system, something rated for mold.