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Summer 2004 Vol. 4 No. 2

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Stachybotrys chartarum, enlarged by scanning electron microscopy, ©SciMAT/Photo Researchers Inc.

It sounds like the plot of a science fiction movie. A dark, slimy mold infests a home and releases toxic substances that infiltrate the tissues and nervous systems of unsuspecting occupants, causing them to develop severe illnesses. Yet this is what some homeowners say actually happened to them when mold flourished in damp spaces in their houses.

Attack of the Indoor Mold

A Scientific Look
at Mold in
Damp Buildings

In an effort to determine the scientific facts about building dampness and mold, a committee of the Institute of Medicine carefully pored over all the studies that have been conducted to date on the health effects of exposure to visible mold in buildings or, more broadly, to the many factors that are associated with building moisture problems. The committee's findings, detailed in a recent report, cast damp, moldy buildings as bad guys, though not necessarily villains of the same ilk as horror-movie monsters.

The committee found enough telling evidence to conclude that the presence of visible mold on damp building materials is associated with the flare up of asthma symptoms in some asthmatics, as well as coughing, wheezing, and upper respiratory tract symptoms in otherwise healthy people. The amalgamation of all the factors related to dampness -- mold, bacteria, dust mites, chemical emissions from wet materials, etc. -- may be associated with the onset of asthma and shortness of breath, but the evidence is less certain in these circumstances. Likewise, the presence of either visible mold or damp conditions in general may be linked to lower respiratory tract illnesses in children, but the evidence is not as strong in this case.

The committee found very few studies that have examined whether mold or other aspects of indoor dampness are linked to fatigue, neuropsychiatric symptoms, or other health problems that some people have attributed to fungal infestations of buildings. The little evidence that is available does not support an association, but because of the dearth of well-conducted studies and reliable data, the committee could not rule out the possibility.

Still, the connections between wet or moldy conditions and respiratory problems, plus the widespread prevalence of moisture problems in buildings, make indoor dampness a public health concern that warrants action. "Indoor dampness is not your friend," said committee chair Noreen Clark, dean, School of Public Health, University of Michigan, Ann Arbor.

The committee urged changes in how buildings are designed, constructed, and maintained. Architects, engineers, building contractors, facility managers, and maintenance staff do not always apply existing technical information on how to control dampness, the report notes. Training curricula and national guidelines on how to prevent moisture problems should be produced and widely disseminated. Guidelines for these professionals should be developed at the national level to ensure consistency.

Mold growing on a piece of ceiling tile, photo courtesy U.S. Environmental Protection Agency

While there is universal agreement that promptly fixing leaks and cleaning up spills or standing water reduces the potential for mold growth, there is little evidence that shows which forms of moisture control or prevention work best at mitigating health problems associated with dampness. The report calls for more research into cleanup methods.

In the meantime, homeowners should quickly fix the source of any dampness problems that they discover and clean up the wetness as thoroughly as they can. If mold is discovered, it should be removed using equipment and methods that limit building occupants' and the remediation crew's exposure to the mold as well as other chemical or biological agents that may be present. Even though it remains to be seen whether moldy, damp environments are associated with stomach problems, memory lapses, arthritis, or other disorders, the links to respiratory problems clearly show a need for appropriate caution.
  -- Christine Stencel

Damp Indoor Spaces and Health. Committee on Damp Indoor Spaces and Health, Board on Health Promotion and Disease Prevention, Institute of Medicine (2004, approx. 380 pp.; ISBN 0-309-09193-4; available from the National Academies Press, tel. 1-800-624-6242; $42.95 plus $4.50 shipping for single copies).

The committee was chaired by Noreen Clark, dean and Marshall H. Becker Professor of Public Health, School of Public Health; and professor of pediatrics, University of Michigan, Ann Arbor. The study was funded by Centers for Disease Control and Prevention.

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Copyright 2005 by the National Academy of Sciences