What does Mold smell like?

Some compounds produced by molds have strong smells and are volatile and quickly released into the air.  These compounds are known as microbial volatile organic compounds (mVOCs).  Because mVOCs often have strong or unpleasant odors, they can be the source of the "moldy odor" or musty smell frequently associated with mold growth.  A moldy odor suggests that mold is growing in the building and should be investigated.  The health effects of inhaling mVOCs are largely unknown, although exposure to mVOCs has been linked to symptoms such as headaches, nasal irritation, dizziness, fatigue, and nausea.  More research is needed to determine whether there are any human health effects from non-occupational indoor exposures to mVOCs.