Mold can grow anywhere!
Every building where the health of the occupants is a concern should be tested for mold. Even some of the cleanest environments can grow mold. All it takes is a little damp air. Mold doesn't have to be outwardly apparent, and can show up even after taking every precaution you can.
Some examples of how damp environments can form include a new leak in a roof, a pipe with a small leak, or condensation around a cold surface. The water from these sources will evaporate into air inside the walls, floors, or ceilings, and after enough time a few spores might find their way in through cracks or on clothing and when they find that damp air they begin growing and multiplying!
It is always recommended to have a certified inspector check for mold in the air if you suspect mold in your home or if you have found water where it does not belong. This is especially true for sensitive areas such as healthcare facilities.
The testing process collects any particles floating in the air over a long period of time, and proves to be the most effective method for detecting mold. This is because mold spreads by releasing spores into the air which disperse through spaces that otherwise could not be visually inspected. The samples are sent off to a certified independent laboratory to be inspected, and the results are returned to the inspector indicating if any mold is present and if so what types.