Mold spores continually drift through the air. When excessive moisture or water accumulates indoors, mold growth will often occur, particularly if the moisture problem remains undiscovered or un-addressed. Mold can grow on wet or moist wood, paper, carpet, and food.
There is no practical way to eliminate all molds and mold spores in the indoor environment. The way to control indoor mold growth is to control moisture.
The attached references provide information regarding mold in residential locations. You may contact the health department in your county to obtain further information on mold or obtain information on environmental consultants that can help identify molds and remediate problems.