Black mold, also known as toxic mold, is the common name for the fungus Stachybotrys charatarum. Most people know of black mold because it often grows in homes or commercial buildings and can be extremely hazardous to human health. It’s often called toxic mold because it produces mycotoxins – the spores in the air that cause severe respiratory ailments.

Black mold got its nickname due to its greenish-black appearance. Because it tends to grow in moist conditions, it can also be identified by its slimy top layer. If its water source dries up, though, black mold can look powdery and dry.

Growth often occurs in the midst of constant moisture – anywhere with excessive humidity, plumbing or other water leaks, condensation, or flooding is a ripe area for black mold growth. These damp conditions, in combination with materials that have high cellulose and low nitrogen content (including fiberboard, gypsum board, paper, dust, and lint) promote black mold growth at alarming rates.

Black mold grows most quickly in warm conditions. Humid climates therefore experience more black mold growth than do others. It grows outdoors as well as indoors, especially in soil and on plants because, again, they consist of a lot of cellulose and not much nitrogen.

When black mold does develop inside the home, it typically grows somewhere not easily visible. Moisture survives best in nooks and crannies, and therefore so does black mold because it requires a continual water supply. Water leaks within walls, above ceilings, under floors, and inside cabinets often harbor significant mold growth for weeks, months, even years before a resident notices the problem.

Fortunately, black mold requires more time to grow than do other types of mold. Whereas other molds can develop within 48 hours after water damage, black mold needs a week or more of sustained moist conditions in order to grow and spread. This requirement is why black mold often grows and incubates in a hidden corner of a residence. Furthermore, once it begins growing, it takes over other molds and claims their environment as its own.

Several harmless molds look similar to toxic black mold. Because black mold is so severely dangerous, all molds should be treated with the same seriousness until a trained technician determines whether it is hazardous black mold or a less harmful fungal strain. The only way to evaluate which kind of mold is present in your home or office is to have a specialized mold expert examine a sample under a microscope.