Mold is nearly everywhere yet is not seen to the naked eye until it gathers in colonies. Its growth rate once provided with with water or even a small amount of moisture is typically exponential. Visible mold represents a lot of mold. 1 million spores per square inch is not an unusual count in a growth colony. Regarding the inside of an enclosed area such as a house or basement disturbing this mold even with the slightest breeze can send tens of thousands of mold spores into the air and unto other non affected areas. That is why mold removal and remediation is done under such strict measures of containment.