As we have seen, the most common reason for a musty smell in your home is the presence of mold or mildew. And because the microbial volatile organic compounds (MVOCs) emitted from mold and mildew have a low odor threshold, a musty smell does not necessarily mean that there is a lot of it.
Musty smells in houses may be attributed to several causes, including: Mold and mildew: Leaky pipes, a damaged roof, high humidity, and exposed dirt in the crawlspace may all contribute to moisture buildup. This moisture combined with the stagnant air and dark corners can lead to the growth of mold and mildew.