Mold is a fungus. This fungus produces spores which are like seeds. When the seeds (spores) have moisture (humidity over 60%) they germinate to active mold. If they have a food source (organic material like wood) they reproduce into colonies producing more spores. Think of Mold as a Plant with a seed. Just like a live plant. The mold spore and plant needs food and water to flourish and when they do it reproduces at an rapid rate. There are 4 stages of Mold starting with stage 1 (Surface Contact Mold). If Stage 1 mold has sufficient food and water it will colonize into Stage 2 (Small Organized Circles) which consist of more spores. As it advances to Stage 3 the Spores in the air will cause a toxic environment. We can test the Air to get a Spore content but even low amounts of air ingested spores can cause health issues.