We place a calibrated air pump in the room or rooms you're concerned about and pull a set volume of air through a sampling device that captures spores as they pass. The same process happens outside for the baseline. Both samples go to the lab together.
The lab reports spore counts per cubic meter for each sample, along with the mold genus present in each. We compare indoor to outdoor and explain what the difference means in plain language: whether it points to an active problem, and roughly where in the home it's likely coming from.
Most homes need one or two indoor samples plus the outdoor baseline. Larger homes or homes with separate HVAC zones sometimes call for more, which we'll discuss with you before scheduling.
Weather plays a role too. We try to avoid sampling right after a heavy storm rolls through, since outdoor spore counts can spike temporarily and skew the baseline comparison. If timing doesn't allow for that, we'll factor it into how we read the results.