It’s important to understand the different types of mold spores. One type is called Basidiospores. It’s often present in high concentrations in outdoor air. In fact, the 80th percentile for December in Washington is 5,000. So, if you have a mold problem, your indoor spore count will likely be in the range of the outside average. That’s why you should always compare indoor results to the outside air sample.
Raleigh Mold Testing 