You may take air samples when trying to identify a hidden mold problem. The total number of spores in the complaint area should be compared to indoor and outdoor controls, or more accurately, “references”. For example, if you find 10,000 spores per cubic meter in the complaint area, and only 1,000 in the reference samples, there is a high likelihood of indoor amplification.
Although it’s important to look at the total numbers, it’s critical to also make comparisons of the types of mold. Each type of mold is unique. There are some types that will predominantly grow on leaves outdoors. These don’t have an apetite for building materials and will rarely be found growing indoors. Other types, however, do have the enzymes needed to digest common building materials in its quest for more food.
A few references can help you make a distinction between types of mold typically found outdoors and those that can grow on building materials. I’ll summarize a few of these references below: