Both our indoor and outdoor environment have mold spores present. There is no such thing as a mold free environment in the Earth's biosphere.
If there are mold problems in a house only during undoubting times of the year, then it is probably either too air-tight, or too drafty. Mold problems occur in airtight homes enhanced frequently in the warmer months (when humidity reaches giant levels inside the house, and moisture is trapped), and occur in drafty homes more Mold Inspection Miami frequently in the colder months (when warm draft escapes from the living operation into unconditioned space, and condenses).