There are over 5 million species of mold/fungi however, less than two dozen are found inside our homes/offices. To make this distinction even easier, we can further break these down into two categories:
Opportunistic molds : Common molds such as aspergillus/penicillium and cladisporiumare the most common. These molds can colonize on elevated humidity without a moisture source. There is no known health threat from cladisporiumso we mostly deal with elevated aspergillus/penicillium when we find it. Finding amplified aspergillus/penicillium almost always relates to an issue with the HVAC system and requires a thorough cleaning to remove it.
Water indicator molds : These molds require an active moisture source to colonize and produce spores. The most widely documented by sampling are stachybotryschartarum, Chaetomium globosum, curvularia, epicoccum and basidiospores (mushrooms). Chaetomium is not technically a mold (it is an ascomycete) with limited production of mycotoxins. It is commonly found alongside other water indictor molds and generally, it is the first mold we find so it acts as a precursor to the condition which may support other water indicator molds.
These molds are heavy, mostly black/dark brown and they produce heavy spores which quickly settle out of the airstream. For this reason, using air sampling to identify these water indicator molds is not effective as the sample may not pick them up.
Mycotoxins : The most common molds which produce mycotoxins are aspergillus (an opportunistic mold) and stachybotrys, curvularia, and epicoccum (which are all water indicator molds). These are the molds which the media/internet hype as “black mold” or “toxic mold” although the fear has never been proven. The studies you find on the internet promoting links between dampness and death have all been disproven in later studies. No children in Cleveland, Ohio died from exposure to mold or dampness.
Are molds harmful?
Amplified molds may produce mycotoxins which can cause allergic reactions, contribute to asthma attacks and compromise pulmonary functions by contributing to other stressors/triggers. The only proven medical condition related to mold/fungi to date is aspergillosis and you should note aspergillus is an “opportunistic mold” rather than the “toxic mold” hyped on the media. I truly believe amplified mold can and does impact our health if we are exposed to long-term or systemic exposure, but that is just my opinion.