In the past few years, toxic mold has become a major health concern to many homeowners. Most of the molds we encounter daily do not pose a health threat to humans. However, some molds release spores that are toxic and when these spores are confined within a house — which can happen as a result of newer airtight construction — they can reach concentrations that make them a serious health threat. In fact, some people can have such an extreme reaction to certain mold-born spores that it is impossible for them to live in any home in which these spores are present.

Since mold can grow in inaccessible areas of a structure or otherwise be invisible to the naked eye, a person selling his or her home could be unaware of the presence of mold even though it may exist on the property. For this reason, if you are buying a home, you should hire a qualified environmental inspector to determine whether the property contains mold or other health hazards. This is especially important if disclosure documents or inspection reports indicate the presence of moisture, standing water, water intrusion or mold of any kind.

If you are selling your home in San Francisco, you will have to complete a Real Estate Transfer Disclosure Statement, which includes a question asking if you are aware of the presence of mold on the property and which may be an environmental hazard. (Most properties have mold, and mold may be an environmental hazard, so most sellers are likely to answer the question by checking “Yes.”) For the time being, sellers have no further disclosure requirements regarding toxic mold. But if your property has been tested for mold, that fact must be disclosed.