Mold is difficult to deal with. Mold spores are microscopic and therefore cannot be seen. What you do see is the black growth that is a result of the presence of mold spores.
The mold spores will travel on the air, so when we arrive at your home, one of the first things we will do is set up containment to make sure that the mold spores do not travel into uncontaminated areas of your home. Often, we will also add a HEPA air filtration system to the containment in order to create a negative pressure that helps contain the mold spores to the work area.