Mold needs to be removed from a homestead if the occupants are to be kept safe, healthy, and comfortable. Mold, mildew, rot, and dust mites are great threats to their health and can induce asthma, allergies, eye and respiratory issues, among others things. They also negatively affect the value of the house, when they damage its structure.
Mold affects the quality of air circulating in a house. It manages to grow fast. It only needs some humidity to start growing immediately. It will also thrive in the cold, as is in a refrigerator, provided it is not too cold. Rotting can also occur in sealed areas and behind drywall. You not seeing it does not prevent it from continuing to spread. It shall keep destroying your house with time. More about molds here.
Mold brings with it significant damage to a house. The rot can get to people, when they touch it, breathe, or eat it unknowingly. When they are exposed to it this way, certain things shall happen to them. They might have difficulty breathing, asthma, and topical skin rashes. Black mold, for instance, is nor common but highly toxic and has carcinogenic mycotoxins which are linked to some kinds of cancer, liver and nervous system damage, and other conditions. They also make it difficult to try and sell a house once infestation creeps in.
Mold removal exercises shall also be expensive, depending on the extent of the damage. There is also the case of many insurance companies excluding the presence of mold in their covers, due to the number of lawsuits they seem to keep on attracting. Click this link for more about this topic.
When you need to prevent their growth in your home, you start by having an operational and energy efficient dehumidifier. Mold does well in dark, damp, humid spaces, and shall, therefore, grow fast in basements and crawl spaces. When you have a dehumidifier active in the house, the house's humidity levels not be conducive for them to grow.
You can also hire experts to remove the mold. They shall rely on the control of moisture and humidity to ensure the mold growth is arrested. They shall first inspect where the mold either grew or is about to. They shall then permanently seal the house, to make it waterproof and prevent mold from finding space to grow. They can also install a crawl space vapor barrier system, for the sake of the house and its occupants.
Anytime you think there is mold growth in your house, do not hesitate to call them in. Any musty smells are an indication of something like this growing. You are better off preventing further growth, than stopping established growths.
Also read https://www.youtube.com/watch?v=GF_nKMD7-dQ.