The health risk of the increases in microbial and non-microbial indoor gas-phase chemicals in indoor air from building dampness are not well understood. Some of the microbial volatile organic compounds (microbial VOCs or MVOCs) released by molds are sources of odors . Some microbial VOCs are known to be irritating if concentrations are sufficient but it is not known whether microbial contamination in buildings can lead to sufficient indoor air concentrations of these VOCs to cause irritation .
As noted above, high humidity or wetted building materials can lead to increased rates of release of formaldehyde — a volatile organic compound — into indoor air. The significant health risks of formaldehyde are discussed in another section of this web site; however, we identified no direct studies of the increased risks from formaldehyde in damp buildings. Alcohols and degradation products from the softening agents used in many plastics can also be released when floor products containing polyvinyl chloride (PVC) are underlain by damp concrete. In several case studies, these chemicals have been cited as a source of odors and irritation ; however, no extensive or systematic studies of the health effects of these chemicals were identified.