Active microbial growth (molds, mildew, bacteria) produces volatile organic compounds (VOCs); these microbial VOCs (MVOCs) cause the musty, mildewy, or earthy odors common to water-damaged or moist building materials. Many of these have extremely low odor thresholds, and many can be quite objectionable.

The following review discusses the published literature on MVOCs; it is organized into two general sections. The first covers literature on the biology and production of MVOCs. The second section of the review concerns field studies that have used MVOC sampling in buildings with known or suspected mold problems.

Different species of molds have been shown to produce specific mixtures, or profiles, of MVOCs, which should prove useful to reveal which mold(s) are growing in a building. There are currently very few MVOC profiles available, though, from many of the molds that commonly occur in buildings. There are a number of other molds that are important in buildings that have not been studied as sources of MVOCs.

In occupied buildings with microbial growth, there often are complaints about air quality and frequently about health effects. These complaints often precipitate building investigations. Thus, it is useful to building owners and operators to understand where and how these pollutants (MVOCs) are released, which molds are likely to be sources, and what are the best analytical tools for MVOCs.

Units: SI