Mold is everywhere. Walk through any room of your house and you’re likely to encounter myriads of mold spores, whether or not you know it. Most of these spores aren’t dangerous. In fact, the majority of these mold spores will be dormant, floating through the air and waiting to find the perfect combination of moisture, warmth and nutrients to thrive.

What Is Black Mold?

Mold is a term for any fungus that grows as multicellular filaments (called hyphae). A number of these species can appear black, but not all black molds are dangerous. In fact, the species of mold that researchers have linked to severe health risks isn’t always black itself.

Homeowners Insurance Mold Infographic

The world of mold is staggeringly vast. No one knows how many distinct species of mold exist, according to the US Centers for Disease Control & Prevention, but estimates range from the tens of thousands to over three hundred thousand. Most of these fungi are not dangerous. Stachybotrys chartarum, on the other hand, can cause serious medical conditions.

How Toxic Is It?

In scientific terms, the species commonly referred to as “black mold” or “toxic black mold” is known as Stachybotrys chartarum (sometimes Stachybotrys atra or Stachybotrys alternans).

Black Mold

Toxic black mold is a misleading name for Stachybotrys chartarum, since the fungi isn’t always black or toxic. Stachybotrys chartarum is actually greenish-black in appearance, but when we talk about toxic molds, we’re really talking about mycotoxins, poisonous chemicals that can be created by some species of fungi.  Stachybotrus chartarum can produce mycotoxins, but sometimes, it doesn’t. Moreover, other species of mold can produce mycotoxins, which are equally dangerous to humans and pets, but these species need not be black or go by the name Stachybotrus chartarum.

Also keep in mind that some species of black mold are not toxic. In short, noticing a black mold where water damage has occurred won’t tell you whether or not your family is being exposed to potentially-harmful toxins.

With these facts in mind, it should be clear that identifying the specific species of mold in your own home is not particularly important. As the US Centers for Disease Control has said, “all molds should be treated the same with respect to potential health risks and removal.” In other words, every mold is bad news.

Why Is Mold Bad For You?

Although the precise function of mycotoxins is still unknown, researchers are certain of at least one crucial fact: these toxins can be very dangerous.

Remember that Stachybotrus chartarum can, but doesn’t always, produce mycotoxins. To complicate matters, the fungi can actually produce a number of different mycotoxins, all of which can have different health effects on residents. One variety of toxins, trichothecenes, are neurotoxic, which means that they can kill neuron cells in the brain. Trichothecenes can be inhaled as an aerosol dispersed in the environment, but are also dangerous upon skin contact.

Most of the health risks associated with black mold exposure, though, are respiratory in nature. The most common symptoms of mycotoxin poisoning involve

  • Coughing and sneezing, often chronic
  • Difficulty breathing
  • Sore throat
  • Eye, mouth and nose irritation and burning
  • Bleeding in the mouth

Inhaling any sort of mold spore, whether or not the mold is actively producing mycotoxins, can lead to respiratory symptoms. That’s especially true for people who have pre-existing lung conditions, are allergic to molds or have compromised immune systems. Some recent research has even linked mold exposure early in life to an increased risk of asthma in children.

Mold isn’t just bad for your health. Fungi grow by eating away at organic substances, including the building materials that are holding your house together. That means rampant mold growth could threaten the structural integrity of a home, just as it puts residents in harm’s way.

How Does Stachybotrys Chartarum Spread?

As a colony grows, the proportion of mycotoxins concentrated in the area will only increase, but the high moisture requirements of black mold growth are in this instance a blessing in disguise. Since Stachybotrys chartarum needs to be damp to survive, the fungi’s spores will be heavy with moisture, inhibiting their ability to spread through the air.

Dangerous species of black mold are most likely to grow in parts of the home that are exposed to excessive humidity and warmth. Stachybotrus chartarum often blooms into colonies of overlapping circular growths, usually in places that are normally hidden from sight, like basements. In practice, however, a mold can grow anywhere there is moisture and a sufficient energy source.

Molds reproduce asexually, by creating spores that can be dispersed throughout the environment. The spores produced by Stachybotrys chartarum, known as conidia, grow in clusters at the end of long stalks, much like the pollen that coats the anther in a flower.

Fungal Spores & Flower Anther

Fungal spores (l), as compared to the anther of a flower

While the spores produced by Stachybotrus chartarum find it difficult to spread, they can and do make their way into the air after being dislodged.

Once airborne, spores can be inhaled by residents, causing severe respiratory conditions, or drift to another surface. Wherever a spore can find moisture, especially constant moisture, it will grow. But Stachybotrus chartarum is particularly fond of materials that are high in cellulose, a category that includes many common building materials. Fiber board, gypsum, paper, carpet, drywall and some brands of insulation are all cellulose-based materials, and thus provide ideal conditions for mold growth, at least when soaked in moisture.

What To Do If You Find Mold

Mold smells and black mold can have a distinctive odor, somewhere between must and mildew. The smell might even lead you to a specific part of the home, although you might not find any visible growth when you get there. Mold often hides behind walls, but don’t begin ripping wallpaper down yet. Disturbing the mold could release a cloud of spores and, in turn, a cloud of mycotoxins. Don’t go it alone, and try to avoid those do-it-yourself mold tests sold in stores, which are notoriously unreliable. Instead, contact a professional mold inspection company to test your home’s air quality.