Air testing can be useful, but it doesn’t always tell the full story. If mold is hidden behind walls, under floors, behind cabinets, or inside HVAC components, spores may not pass through the air sample during the short testing window. That means a home can still have hidden mold even when an air test comes back normal. In this article, we’ll explain what air testing actually measures, why hidden mold can be missed, and when a mold dog inspection may be a better next step for locating the source.