Air sampling using spore trap cassettes is one of the most widely recognized methods for testing airborne mold. This method captures mold spores that are suspended in the air by pulling a measured volume of air through a specialized cassette using a vacuum pump. Inside the cassette, spores and other particles are trapped on a sticky slide, which is then analyzed under a microscope at a lab.

The results of spore trap testing are typically reported as the number of spores per cubic meter of air, along with the genera of mold that were found. The test gives a snapshot of the air at a specific moment in time and is often used to evaluate indoor air quality before and after remediation, compare indoor and outdoor mold levels, or support a more comprehensive investigation.

While this method requires special equipment and is usually done by professionals, some homeowners or renters may be able to perform it themselves if they can rent or borrow the necessary tools.