Question: We’ve been told we have “black mold” in our 2 bathrooms. We’re trying to replace the lino. What is black mold? What do we do or who do we call? We’re in Edmonton.

Answer: The term “black mold” could refer to any mold that appears black. However, one mold that appears greenish-black and that has had a lot of publicity since the 1900s due to it’s toxicity is Stachybotrys. Stachybotrys is therefore erroneously referred to as black mold by the general public. There are several species of Stachybotrys but the one commonly associated with ill health is Stachybotrys chartarum. For the purpose of this discussion, the term “black mold” will be used here to mean Stachybotrys.

Black mold  grows best in highly damp and moist conditions. It is very common on water damaged cellulose containing building material such as fiberboard, gypsum board, paper, dust, and lint. Growth of black mold occurs when there is excessive moisture due to excessive humidity, water leaks, condensation, water infiltration, or flooding. The basement, interior of wet wall cavities, bottom of carpets, and behind wet baseboards provide a perfect breeding environment. Conducting a  house inspection  can help locate and identify moisture problems that result from excess humidity or condensation, even if they occur behind walls.  If you have leaks from pipes or plumbing fixtures, their cause should be identified and fixed before addressing any cleanup of black mold.

Any type of mold is potentially a health hazard. Black mold toxins have been reported to cause lung bleeding which can lead to death among infants. It has also been shown to trigger asthma attacks and other allergies both in children and adults with compromised immune systems.

As for what to do, I would suggest you contact a qualified professional to assess the extent of mold contamination, determine the cause (or source of moisture) and advise on the appropriate way to correct the moisture problem and cleanup the mold.