The three most common methods of testing for mold are air testing, surface testing and bulk testing. Each test measures something different, so it’s best to do all three tests. And do them in different areas of your home at different times of the day.
Air Testing: Tests the concentration of spores in the air in your home. Lets you know if you have mold even if you haven’t seen or smelled it. The drawback with air testing is that the spore count can change dramatically in a short time, and results will vary throughout the day.
Surface Testing: Samples are taken from household surfaces by swabbing or tape-lifting them. In a laboratory, the samples are analyzed to determine how much mold is deposited throughout the house. The drawback is that mold and its spores are not spread evenly on the surfaces around your home, and results vary according to time and place. Also, surface testing cannot determine the exact concentration of spores in the air.
Bulk Testing: Pieces of material (e.g., carpet, wallpaper, wood) are collected from various areas of the home and taken to a laboratory. The material is examined under a microscope to determine (1) if you have a mold problem; (2) if mold is present, what species it is; and (3) what the concentration of mold particles is. The drawbacks are that the test cannot determine if spores are being released into the air and the possibility of spreading the mold while collecting the samples.