Introduction to mold testing and sampling An IAQ or “mold investigator” cannot reliably identify a mold genera or species growing on a Building surface by the naked eye. Despite the recent public fear created by media attention, including a now-refuted “Toxic black mold” Stachybotrys chartarum study involving infant illness and death, it is simply not the case that “black mold” in Buildings is necessarily a danger to occupants. In fact, having investigated many Buildings quite carefully, I assert that in most cases the “black mold” that you see in Buildings is most often an “indicator organism” telling you that conditions are right for mold formation. we have often found more problematic molds in such properties, such as species of Aspergillus sp. or Penicillium sp. which are airborne, travel in the Building, and are more likely to be bothering the occupants than a large, sticky, non-easily-airborne spore like S. chartarum. These harder to see, often light-colored molds, are quite often missed entirely by inexpert owners and amateur “mold inspectors” who go on to collect, over-report the occurrence of, and react to the “black stuff.” One result has been unnecessary expense for “mold testing” and in some cases unnecessary mold remediation. Some of our articles, as well as writing by others who study this field, address these problems and offer help in deciding what level of trouble and expense are appropriate.