There are websites with labs which do this, but they do break the bank. They send a cloth for you to rub different places in the house, and they then test the dust on the cloth. But learn from me...I rubbed the cloth on tops of old paintings in one room and the results showed miserably high mold in that room. No, it was because I rubbed the tops of old paintings that had previously been in moldy houses before this one. When I did a mold air test of the same room, it was great. So perhaps a mold air test??? It was $75 for the inside, then they did it outside to compare--another $75.