Common Questions
What does mold smell like, and what does a musty smell mean?
Answer
Mold often smells musty or earthy. The odor comes from gases molds give off as they grow, called microbial volatile organic compounds (mVOCs). EPA says a moldy smell with no visible source is one sign of hidden mold, behind drywall or wallpaper, under carpet, inside ductwork or above ceilings.
The smell itself is a clue, not a diagnosis, and covering it up doesn't solve anything: the odor goes away when the mold is removed and the moisture fixed. EPA notes mVOCs have been linked to symptoms such as headaches and nasal irritation, though research is still early.
Our recommendation
If a room smells musty and you can't find the source, have a licensed Mold Assessment Consultant look for hidden mold before opening walls; disturbing hidden growth can release a lot of spores.
What the sources say
“Because these compounds often have strong and/or unpleasant odors, they can be the source of odors associated with molds.”
“Exposure to mVOCs from molds has been linked to symptoms such as headaches, nasal irritation, dizziness, fatigue, and nausea. Research on mVOCs is still in the early phase.”
“You may suspect hidden mold if a building smells moldy, but you cannot see the source”
“For example, removal of wallpaper can lead to a massive release of spores from mold growing on the underside of the paper.”