Carla Martin couldn’t understand why she and her family kept getting sick all the time. Watery eyes, coughing, skin rashes — the variety of symptoms made it difficult to know whether the illnesses were related. But Carla had a hunch. They had just moved into a new home, and the sudden onset of all these odd sicknesses couldn’t be a coincidence. Could it?

One day as she walked into the upstairs bathroom the musty odor she had almost gotten used to triggered a vision of mold. She had heard about mold problems in houses before. But where was it?

“I called a home inspector who specialized in mold,” said Carla. “Within a few minutes he had opened up the bathroom wall and called me to come look inside.”

What Carla saw inside the damp wall was a large patch of dark green slime with white edges. Later the inspector found a slow leak in the faucet valve that was causing the mold.

Which Molds Are Dangerous?

We all have mold in our home somewhere, and ordinary mold is not usually harmful. But “black mold” refers to certain kinds of mold that are dangerous. The technical name for these dangerous molds is stachybotrys, and it is often called stachybotrys chartarum or stachybotrys atra. It is a very common mold in North America.

Stachybotrys mold is dangerous because its spores — the microscopic seeds it releases into the air to spread itself — contain harmful toxic substances called mycotoxins (actually all mold spores contain mycotoxins but stachybotrys mycotoxins are unusually harmful). People breathe these spores and the toxin gets into their system, causing all kinds of unhealthy symptoms.

There are other molds with dangerous mycotoxins, notably Aspergillus, but Stachybotrys is the one that is most commonly found in homes.