There are many types of mold that are black, and most are not “toxic black mold.”

The “toxic black mold,” Stachybotrys chartarum, is most often found on drywall that has been wet for several days. There are dozens of other kinds of common, black molds, including Cladosporium (found outdoors as well as indoors, on window frames and in attics), and Ulocladium and Chaetomium (found on damp drywall).

Tape and swab samples are the simplest types of black mold testing. Most mold inspectors then send the sample to a testing lab for analysis. You may also want to know if you are breathing in Stachybotrys mold spores, so you may request to have an air sample taken as well. Just remember that if a mold inspector is going to take an air sample, the air sample should be taken before the surface sample, for a realistic measure of your exposure.

If the black mold testing reports the presence of Stachybotrys chartarum spores, there are two comforting thoughts to keep in mind. First, not all Stachybotrys colonies contain toxins. On average, about two-thirds of them do not. And second, Stachybotrys spores are larger than many other mold spores, and thus do not remain airborne for extended periods of time. Unless the mold is disturbed, high concentrations of the spores will not be present in the air you breathe. I’ve done black mold testing in many environments in which many surfaces were covered with Stachybotrys mold, and rarely did I find many spores in my air samples.

People can carelessly disturb Stachybotrys mold, however, particularly when they are removing moldy drywall in renovation or remediation work. If you find what you think may be black mold in your home or office, don’t jump to conclusions that you are looking at “toxic black mold.” But don’t touch it, either. Hire a mold inspector to do black mold testing – preferably one who does not work for a mold remediation company.

If you want to understand why and where mold grows, learn how to get rid of it and prevent it from returning, buy a copy of The Mold Survival Guide: For Your Home and for Your Health, Jeffrey C. May and Connie L. May (2004). Jeff May is also author of My Office is Killing Me! The Sick Building Survival Guide (2006) and co-author of Jeff May’s Healthy Home Tips (2008). All three books are published by The Johns Hopkins University Press and are available on amazon.com.