You shoud learn about what mold is and where it thrives. All molds are fungi, just like mushrooms and lichens, for example. The mold that is toxic to people is relatively rare in the fungus kingdom, meaning most kinds aren't dangerous. However, some are dangerous, so any mold in your home or business must be mitigated and completely removed.
The rule of thumb is to contact a home mold removal Brea CA company to get rid of the mold if it is more than 9 square feet.. If you see mold growth, there is probably more behind walls, in attics and elsewhere.
Before you hire any expert, check that they are certified properly and that they are approved by groups such as the Restoration Industry Association, the Institute of Inspection, Cleaning and Restoration and Contractor Connection.
You need to mitigate any mold growth you find to stop further harm, and do it now. If you don't, parasitic fungi will continue to feast on your home or business and will ruin your things.