Why is Outdoor Air Quality Sampling Necessary?
What many people may not be aware of is that just like germs or viruses, mold spores are everywhere. Mold testing is not just looking for the presence of mold, it is meant to determine the concentration of mold. In some cases, the concentration of mold spores outside of your home might be very high due to heavy rains or a large body of standing water. In that case, the concentration of mold is likely to be fairly high inside your home as well, but it will not be as high as the concentration of mold outside.
This is why it is important to take both indoor and outdoor air quality samples. If the air quality sample taken indoors reveals a lower concentration of mold spores than one taken outdoors, then the source of the mold is most likely outdoors. If the air quality sample taken indoors reveals a higher concentration of mold spores, then the source of the spores is most likely in the house. It is important to take both indoor and outdoor samples to determine the source of the spores, however.
It is also important for mold inspectors to take outdoor and indoor samples at the same time. Weather and other factors can have a significant impact on the concentration of mold in the air. After heavy rain, there will naturally be a much higher concentration of mold spores than during a dry spell. Wind, however, can also come in and pick up spores that were lying dormant, which can also lead to a higher-than-normal concentration of spores. If an inspector takes an indoor sample on a day when there is little wind and an outdoor sample when there is a strong breeze, the outdoor air quality sample will show a much higher than an average number of spores, which might lead the inspector to erroneously believe the mold is coming from outside the home when it is actually inside.
Mold specialists will also take a number of different samples from various areas inside and outside of your home. This can help them determine the most likely location of the mold, even if it is hidden behind walls or under carpeting. The closer the sample taken is to the source of the mold, the more heavily concentrated the spores will be in the sample. When they find the highest concentration of mold spores, that tells them where to start looking for the actual mold.