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Institute of Medicine (US) Committee on Damp Indoor Spaces and Health. Damp Indoor Spaces and Health. Washington (DC): National Academies Press (US); 2004.

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Damp Indoor Spaces and Health.

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7The Public Health Response

Studies reviewed in this report indicate that:

  • Dampness is prevalent in residential housing in a wide array of climates (Chapter 2);
  • Sufficient evidence of an association exists between signs of dampness and upper respiratory tract symptoms, cough, wheeze, and asthma symptoms in sensitized persons (Chapter 5);
  • Sufficient evidence of an association exists between signs of mold and upper respiratory tract symptoms, cough, wheeze, asthma symptoms in sensitized persons and hypersensitivity pneumonitis in susceptible persons (Chapter 5).

The committee concludes, on the basis of this information and other findings presented in Chapters 2 through 6, that excessive indoor dampness is a public health problem.

This chapter draws together findings and recommendations presented in earlier parts of the report and places them in the context of the mission of public health to “[fulfill] society's interest in assuring conditions in which people can be healthy” and its aim “to generate organized community effort to address the public interest in health by applying scientific and technical knowledge to prevent disease and promote health” (IOM, 1988). It addresses the public health interest in housing, barriers to the adoption of dampness prevention and reduction measures, and public health approaches to addressing the problems created by damp indoor environments. The chapter also operationalizes some of the findings, recommendations and research needs presented in earlier chapters by suggesting specific actions and actors to implement them.


The influence of housing and the workplace on human health has long been an element of public-health action and research (Susser, 1973). With the industrialization of the United States, responsibility for workplace, housing, and public-health improvement efforts was clearly distinguished at the local and national levels (Duffy, 1974; Galishoff, 1988; Melosi, 2000; Rosner, 1995; Veiller, 1921). The sanitary-reform movement during the 1800s sought locally and federally to rectify the hazardous effects of overcrowding, insufficient light and air, impure water, and the like associated with inadequate housing. Similarly, the mechanisms through which housing promotes health or disease became the focus of considerable research related to public health (Dedman et al., 2001; Dunn and Hayes, 2000; Matte and Jacobs, 2000). The societal obligation to ensure safe and healthy housing and workplaces has long been evident in building codes and zoning policies, which, according to Freeman (2002), are

prima facie evidence that America has deemed a certain standard of housing a basic requirement of civilized society. If this were not so, we would allow the poor and homeless to build shantytowns, as is done in many cities of the Third World.

The environments in which we live and work, then, are widely accepted as determinants of our health; and, as this report delineates, damp buildings may pose a health risk.

Research also indicates that damp buildings have economic implications. Nguyen and colleagues (1998) examined direct costs (in inpatient care, drugs, physicians, and nursing and clinic services) and indirect costs (in lost work days and duration of disability) of asthma and other respiratory diseases associated with the presence of moisture and mold in residences in Finland. The authors estimated the cost of asthma associated with moisture in buildings in 1996 at 137.5 million Finnish markkaa, which translates to about U.S.$6.06 per person.1 The corresponding per capita cost associated with mold in buildings was about U.S.$3.20. Such estimates are necessarily based on simplifying assumptions and are subject to substantial uncertainty, but they highlight the fact that the effect of indoor dampness on health has an economic dimension and that cost-effectiveness studies are needed to assess the savings that damp-building prevention or remediation might generate by reducing morbidity.

As noted in Chapter 2, dampness is more likely to be found in buildings that are older, lack central heating, are poorly insulated (and hence subject to cold and damp conditions), and are overcrowded. Buildings with those characteristics are most evident in low-income communities (Krieger and Higgins, 2002).


Chapter 6 identifies many technical measures and practices that could prevent or reduce problematic indoor dampness. However, social and institutional barriers hinder their widespread adoption.

One important barrier is poverty. Historically, the distribution of poor housing stock in the United States—as in many other nations—has been largely associated with socioeconomic status (Evans and Kantrowitz, 2002) and ethnicity (Lawrence and Martin, 2001). Ostensibly, the population at greatest risk of exposure to dampness-related health problems in the United States is the population that is the most poorly housed. Census statistics indicate that the poor are more than three times as likely (22% versus 7%) to have substandard-quality housing (Evans and Kantrowitz, 2002) and that blacks and low-income people are more likely than the general population to be in housing with severe physical problems (Krieger and Higgins, 2002).

Given the costs of maintaining a clean, dry, well-heated, and properly-ventilated home, it should not be surprising that low-income families are more likely to have substandard housing and to live in the kind of damp interiors that may be associated with health problems. Children in such families may bear an additional burden because they are more likely to be in school buildings that have environmental problems: poor plumbing, inadequate heating, and poor indoor air quality (Evans and Kantrowitz, 2002). Reviewing data accumulated in the second National Health and Nutrition Examination Survey (NHANES II) and the Harvard Six Cities Study, Eggleston (2000) concluded that ethnicity, poverty, and residence combined to influence asthma prevalence in inner-city children in ways that could not be easily disentangled.

Economic factors may encourage poor building practices. Combinations of pressure to build quickly and cheaply can result in poorly constructed buildings that are more likely to have water leaks. Under ordinary circumstances, the market works to sift out builders that produce shoddy construction. However, in low-income neighborhoods—where options are limited because there is a shortage of affordable housing—and in other circumstances in which demand outstrips supply, the market may not penalize poor workmanship effectively (Parker, 1994).

Poverty combined with the lack of affordable housing may also create incentives to forgo or limit investment in maintenance that might help to prevent moisture problems. Landlords have little incentive to spend money on repair when there is a surplus of people ready to accept any kind of lowrent shelter (Ehrenreich, 2001). As already noted, those pressures also result in overcrowding, which can lead to excessive indoor moisture and condensation problems (Markus, 1993), which in turn promote mold and bacterial growth.

There are also other barriers to the implementation of dampness prevention or reduction measures. The 2000 Institute of Medicine (IOM) report Clearing the Air: Asthma and Indoor Air Exposures noted that “the relevant features of building design, operation, and maintenance may be determined substantially by speculative builders or other decision-makers who are substantially unaffected by future moisture problems” (IOM, 2000). Such market imperfections isolate decision-makers from the consequences of their choices and may thus lead to socially undesirable outcomes. Insufficient awareness and training about dampness, its prevention, and its consequences and the lack of a clear definition of the environmental conditions and practices that are harmful to health also hinder actions. The following pages discuss those impediments and means of addressing them.


If excessive indoor dampness is a public health problem, then an appropriate public health goal should be to prevent or reduce the incidence of potentially problematic damp indoor environments, that is, environments that may be associated with undesirable health effects, particularly in vulnerable populations. However, there are serious challenges associated with achieving that goal. As the literature reviewed in this report indicates, there is insufficient information on which to base quantitative recommendations for either the appropriate level of dampness reduction or the “safe” level of exposure to dampness-related agents. The relationship between dampness or particular dampness-related agents and health effects is sometimes unclear and in many cases indirect. Questions of exposure and dose have not, by and large, been resolved (see Chapters 3 and 4). An additional challenge is posed by the fact that it is not possible to objectively rank dampness-related health problems within the larger context of threats to the public's health. As the report notes, there is insufficient information available to confidently quantify the overall magnitude of the risk resulting from exposures in damp indoor environments. Even if those data were available, the choice of metric used for ranking—the number of illnesses or the cost of lost work and school days, for example—would greatly influence the result.

What then can be done through public health mechanisms to prevent or reduce the incidence of damp indoor environments? At least seven areas of endeavor deserve discussion with relation to the agents and exposures examined in this report:2

  • Assessment and monitoring of indoor environments at risk for problematic dampness.
  • Modification of regulations, building codes, and building-related contracts to promote healthy indoor environments; and enforcement of existing rules.
  • Creation of incentives to construct and maintain healthy indoor environments.
  • Development, dissemination, and implementation of guidelines for the prevention of dampness-related problems.
  • Public-health-oriented research and demonstration projects to evaluate the short-term and long-term effectiveness of intervention strategies.
  • Education and training of building occupants, health professionals, and people involved in the design, construction, management, and maintenance of buildings to improve efforts to avoid or reduce dampness and dampness-related health risks.
  • Collaborations among stakeholders to achieve healthier indoor environments.

The separate areas are discussed in greater detail below.

Assessment and Monitoring

Although poor housing and health problems are especially evident in low-income populations, the problems created by indoor dampness are by no means limited to the homes of poor people, and they extend beyond homes to workplaces, schools, and other commercial and public buildings. If interventions are to be effective, an accepted first step is to establish mechanisms for identifying existing or potential problems and their determinants. At least one local health jurisdiction in the United States has systematically collected and analyzed data on the adequacy of housing (Marsh, 1982), but there appear to be few, if any, current population-based, systematic efforts to identify and anticipate trouble spots (Krieger and Higgins, 2002). Some general population surveys that include collection of data on dampness and specific dampness-related exposures have been conducted.

Comprehensive data on the prevalence of dampness in residences are collected as part of the biennial American Housing Survey (U.S. Census Bureau, various years), which gathers information on the prevalence of water leaks with outdoor and indoor sources. The number of households surveyed has varied between roughly 88,000 and 106,000 over the years 1985–2001. Data indicate that over that time span there was little difference between the overall incidence of outdoor leaks and the incidence in homes occupied by blacks, the elderly (65 years old or older) or those below the poverty level. Leaks with indoor sources were more likely in homes occupied by blacks and less likely in the homes of the elderly than in the average home. It should be remembered that the data do not record how able the occupants were to respond to instances of leakage—a major factor in whether a particular incident becomes problematic.

As noted in Chapter 2, a primary challenge in formulating a public-health strategy in response to indoor dampness is that there is no generally accepted definition of dampness or what constitutes a “dampness problem” and no generally-accepted metric for characterizing dampness. Studies of specific populations conducted as part of research projects (summarized in Table 2-1) show a wide range of estimates of the number of homes with dampness problems or water damage. In recognition of that diversity, the committee recommends that precise, agreed-on definitions of “dampness” be developed to facilitate greater uniformity (and thus comparability) in the data collected by researchers and the actions taken by those involved in prevention and remediation. That will permit important information to be gathered about mechanisms by which dampness and dampness-related effects and exposures affect occupant health.

Efforts to survey the prevalence of indoor allergens and other environmental health risk factors comprehensively have also been carried out. The National Survey of Lead and Allergens in Housing (NSLAH) was designed to assess the potential exposure of children to a variety of agents, including bacterial endotoxins and allergens of the fungus Alternaria alternata (Vojta et al., 2002). A companion study—the First National Environmental Health Survey of Child Care Centers—used methods similar to those of NSLAH to evaluate exposures in licensed day-care centers (Viet et al., 2003). Both efforts collected qualitative information on the presence of dampness and mold. Publications describing the findings of those studies were in preparation or in press when the present report was completed.

The committee did not identify any current surveillance of mold or other dampness-related exposures in homes.3 A Connecticut law, however, establishes requirements for assessment and monitoring efforts in the state's public schools: Public Act 03-220, “An Act Concerning Indoor Air Quality in Schools,” requires boards of education to provide for a uniform program of inspection and evaluation of indoor air quality in schools, citing the Environmental Protection Agency (EPA) Indoor Air Quality Tools for Schools Program (U.S. EPA, 2000) as an example. The program includes review, inspection, or evaluation of the “potential for exposure to microbiological airborne particles, including, but not limited to, fungi, mold and bacteria”; moisture incursion; and a number of other building and maintenance factors related to indoor air quality. Boards of education are required to perform an evaluation before January 1, 2008, and every 5 years thereafter of every school building that is or has been constructed, extended, renovated, or replaced on or after January 1, 2003. No information on the implementation of the law was available at the time the present report was completed.

Despite its intuitive appeal, there is reason to have modest expectations about the extent to which general surveillance for indoor microbial agents would inform public-health decision-making at this point. As was mentioned in Chapter 3, no exposure standards have been established for molds or other dampness-related agents, although some occupational-exposure limitations were under discussion at the time this report was completed. Among the factors hindering the development of standards are uncertainties over which dampness-related exposures and at what exposure levels may be harmful and limitations associated with all the established means of exposure measurement. Qualitative indicators of the presence of mold also have limitations. The presence of visible mold—even toxigenic genera—is not an absolute indicator that health problems will result. The absence of visible mold also is not an absolute indicator that a building is free of infestation; there may be hidden sources.

The committee recommends (Chapter 2) that the determinants of dampness problems in buildings be studied to ascertain where to focus intervention efforts and health-effects research. The present state of the science, however, is insufficient to support a general assessment and monitoring effort for mold or other dampness-related agents for public-health policy purposes.

Modification of Regulations, Building Codes, and Building-Related Contracts

As detailed in Chapter 6, the use of suitable materials, appropriate design and construction techniques, and common-sense maintenance practices can be expected to prevent or dramatically reduce building dampness and problematic water accumulation. Existing local, state, and national codes and methods of code enforcement may not, however, be sufficient to ensure that good practices are implemented. Indeed, some existing codes may inadvertently promote dampness. Chapter 2 notes, for example, that most codes require passive or active ventilation of crawl spaces; the entry of warm, humid outdoor air into ventilated crawl spaces, which are often cooler than outdoors, is a moisture source for the crawl space.

Some official entities have introduced code provisions that specifically address building dampness. In 2002, the California Occupational Safety and Health Standards Board promulgated the following new section in its “General Industry Safety Orders”:

(g) When exterior water intrusion, leakage from interior water sources, or other uncontrolled accumulation of water occurs, the intrusion, leakage or accumulation shall be corrected because of the potential for these conditions to cause the growth of mold. (Chapter 4, Subchapter 7, Article 9, §3362)

Numerous codes address water and moisture control and ventilation in general (Alliance for Healthy Homes, 2003). However, many of them “are based primarily on practical experience within the building sector or on non-health-related criteria such as perceived acceptability of air (for example, immediate perception of odor or irritation)” (Mendell et al., 2002). The effectiveness and cost effectiveness of codes with regard to health-risk reduction have not been systematically studied. The committee thus recommends, on the basis of its review of the evidence presented in Chapter 2, that current building codes be reviewed and modified as necessary to reduce dampness problems. It cannot draw any informed conclusions about code enforcement, but common sense suggests that more-rigorous enforcement—especially in low-income housing—may yield health benefits for residents.

Another strategy that might be considered is changes in contracts—lease agreements, professional liability-insurance terms, contracts between builders and owners, maintenance contracts, and the like—that would promote building design, construction, operation, and maintenance practices that reduce the potential for dampness problems or that would clarify the responsibilities of parties. Model contract language could be formulated by consensus groups for possible use by individuals or in communities.

Economic and Other Incentives

Action on the part of residents living in damp environments, builders, building owners, and other stakeholders will be required to change the present level of effort applied to preventing or reducing building dampness. Economic incentives are one well-established means of achieving such policy goals. Although specific examples of incentives for policy change related to the prevention of damp environments could not be located, there is precedent for using them in fire prevention and energy efficiency. Mills (2003) cites several examples of premium reductions and other incentives for actions and training that promote fuel conservation and for safety measures that result in cost savings to the insured and insurers. Such strategies depend on actuarially sound methods for quantifying problems and assessing expected benefits—a feature that poses considerable challenges when applied to the assessment of health effects of damp buildings. However, estimates of the health and productivity gains resulting from improvements in indoor environmental characteristics in general have been generated, and these suggest that the benefits may be considerable (Fisk, 2000).

Chapter 2 indicates that research is needed to determine the societal cost of dampness problems and to quantify the economic effects of design, construction, and maintenance practices that prevent or limit dampness problems. Such data would facilitate more informed evaluation of the priority that should be assigned to dampness interventions in the wide spectrum of housing-related issues. Inasmuch as housing stock, climatic conditions, and other factors vary across the country, this research may best be conducted on a state level (via departments of health or departments of social services) or a regional level, perhaps with a common protocol and funding. Climate, geography, and building type all influence indoor moisture levels and shape which problems are most likely to occur and which interventions may be most effective.

Incentives that address dampness might take several forms. The committee did not address the topic in detail, but it offers the following as examples of studies or experiments that might be undertaken to assess their effectiveness in reducing dampness problems:

  • Governments could provide tax incentives, low-interest loans, streamlined application procedures, or other means to facilitate dampness-remediation efforts. For example, a provision of Connecticut Public Act 03-220 allows the state commissioner of education to approve applications for grants in excess of $100,000 for projects to remedy a “certified school indoor air quality emergency” (as determined by the state Department of Public Health) without seeking legislative approval.
  • Health departments could be given permission to levy fines if water-leak problems in rental properties are not corrected after a specified period.
  • Those responsible for the maintenance of public housing, office buildings, or schools could receive bonuses for meeting a defined set of goals for the prevention or reduction of dampness-related conditions (such as leaky roofs) or problems. Such programs could first be pilot-tested in government-owned buildings.

Guidelines for the Prevention of Dampness-Related Problems

Chapter 6 discusses several sets of guidelines for the assessment and management of mold-remediation activities that were developed by various government agencies and professional organizations. However, there is a lack of analogous guidance on preventing—or, more realistically, limiting the opportunity for—the conditions that might precipitate the need for such remediation. Guidelines are typically easier to develop than regulations or other more formal instruments but can still have great effect if they earn status as professional standards of care.

Prevention is a foundation principle in public health, and the committee believes that there is a need to develop and disseminate guidelines on building design, construction, operation, and maintenance for prevention of problematic damp indoor environments. Ideally, development should take place at the national level to promote their widespread adoption and help to avoid the proliferation of multiple and possibly conflicting sets of advice. Stakeholder groups should play an active role in providing input for the guidelines, but they should not be the organizing or sanctioning body for the effort in order to promote its credibility and general acceptance. The committee suggests that any effort to develop guidelines for prevention of problematic damp indoor environments take the following considerations into account:

  • The guidelines should be formulated with multidisciplinary input and with input from a wide array of stakeholders.4
  • The costs of implementing actions should be evaluated and their expected benefits identified.
  • The guidelines should account for how differences in climate, geography, building type, and building age influence vulnerabilities to dampness and the best approaches to prevention.
  • To be effective, the guidelines should go beyond simple prescriptive application of available science and technology; professional judgment should be allowed.
  • Draft guidelines should be subject to external review.

Because the prevention of problematic dampness is just one of a set of interrelated factors that can affect the indoor environment and the health of its occupants, consideration should also be given to developing the guidelines in the context of a wider set of principles that guide the creation and maintenance of healthy buildings.

Public-Health-Oriented Research and Demonstration

Prevention and control of building dampness are hampered by the lack of evidence regarding the effectiveness of various interventions. Clearing the Air (IOM, 2000), for example, acknowledged the logic of reducing dampness as a method for reducing asthma symptoms related to indoor dampness but noted that “no intervention studies clearly document that any form of dampness control works effectively to reduce symptoms or to reduce chances of asthma development.” Additional support for that observation is provided in Chapters 2 and 6 of the present report.

Although there are references in the public-health literature to household-level housing interventions to improve health status, randomized controlled trials are comparatively rare. A review of studies of the relationship between housing interventions and improvements in health identified only 18 (11 prospective and seven retrospective) that evaluated effects on health, illness, and a variety of social measures (Thomson et al., 2001). Only six of the prospective studies and three of the retrospective studies included a control group. The researchers found that many studies showed improvements in self-reported health or reductions in symptoms after the intervention, but “small study populations and the lack of controlling for confounders limit the generalisability of these findings” (Thomson et al., 2001).

A later review by Saegert et al. (2003) examined a wider array of intervention studies but restricted the analysis to investigations conducted in the United States in 1990–2001. They found 72 studies; 21 (29%) addressed asthma triggers or air-quality hazards (including moisture or mold). Among the characteristics noted was that 85% of the interventions were one-time efforts—a single training program, cleaning or remediation. The type of intervention performed was almost evenly split among environmental improvements (31%), participant education (32%), or both (35%). Although 81% of the studies reported the interventions to be successful, only 51% indicated that the measured improvement was sustained. The authors observed that some common factors were associated with success in intervention studies:

  • “Technological interventions appear most successful when the technology is effective, cheap, and durable and requires little effort to maintain or use. Such interventions are especially effective if accompanied by behavioral or knowledge training, and if hazard amelioration can be successfully accomplished through individual-level efforts alone.”
  • “Involving people more deeply in the solution of health problems, especially by home visits, appears to be especially effective and can improve multiple health outcomes.”

The Seattle-King County Healthy Homes Project (Krieger et al., 2000, 2002, 2003) is among recent demonstration and research efforts that included a moisture or mold component. The project targeted 274 low-income households in the Seattle area that included a child with diagnosed asthma. Participants were randomly assigned to a “high-intensity” group (n = 138), which received comprehensive intervention services, or a “low-intensity” group (n = 136), which received a single home visit and limited services. (The low-intensity group received additional services at the completion of the 1-year study period.) For the high-intensity group, community health workers provided home assessments of several potential allergens associated with asthma and other risk factors (including dust, house dust mites, cockroaches, environmental tobacco smoke, rodents, and pesticides), followup education on how to prevent their occurrence or limit their effects, and in some circumstances active interventions to change the indoor environment. The mold and moisture portion of the assessment found that 77% of participant homes had “moisture problems” and over 20% had signs of water intrusion (Krieger et al., 2002). Several possible interventions were identified, including education on moisture sources and barriers, provision of cleaning materials, replacement of moldy shower curtains, installation or inspection and cleaning of ventilation fans, plugging of holes leading to the interior, and installation of vapor barriers. However, the authors noted that implementation of some of the more rigorous building interventions was beyond the resources of the study and that participants did not have the means to perform them independently. At the end of the study period, children in the high-intensity group experienced a greater decrease in asthma-symptom days (4.7; 95% CI, 3.6–5.9; vs 3.9; 2.6–5.2) and a statistically significant decrease in urgent health-services use (15%; 6.3–23.6%; vs –3.8%; –13.1–5.4%) compared with the low-intensity children (Krieger et al., 2003). That translated to an estimated $6,301–8,854 savings in urgent-care costs over a 2-month period relative to the low-intensity group. “Excessive moisture” in the home was reported to have decreased significantly in the high-intensity group,5 whereas no significant changes occurred in the low-intensity group; no changes in the presence of mold were observed in either group. The degree to which the improvements were a consequence of the dampness-related portion of the intervention program is not known.

The Seattle effort and similar ones conducted as part of the National Cooperative Inner-City Asthma Study (Crain et al., 2002; Sullivan et al., 2002) and in Detroit (Parker et al., 2003) show that interventions at both the household and community levels can be mounted and targeted at a specific disease for susceptible people. Local health jurisdictions—such as Boston, Cleveland, and New York City—have developed comparable community wide “Healthy Homes” initiatives related to asthma and chemical hazards (Krieger and Higgins, 2002).

The Department of Housing and Urban Development (HUD) has provided grants to the Cuyahoga County (Ohio) Department of Development and the Illinois Department of Health to fund targeted mold and moisture interventions under its Healthy Homes Initiative (HUD, 2003a). The programs include education; environmental, biologic, and medical monitoring; and in some cases remediation. The projects are going on now, and no results had been published as of late 2003.

Virtually no data are available to compare effects of different interventions and intervention strategies. There is thus insufficient information to draw conclusions on the benefits of specific public-health-oriented housing interventions specifically related to moisture or mold. Existing research on exposure to indoor environmental agents in general suggests that targeted, intensive interventions may yield health benefits. And, as documented in Chapter 6, there is universal agreement that prompt remediation of water intrusion, leaks, spills, and standing water substantially reduces the potential for growth of dampness-related microbial agents and dampness-related degradation of building materials and furnishings.

The committee recommends that carefully designed and controlled longitudinal research be undertaken to assess the effects of population-based housing interventions on dampness and to identify effective and efficient strategies. As part of such studies, attention should be paid to definitions of dampness and to measures of effect; and the extent to which interventions are associated with decreased occurrence of specific negative health conditions should be assessed when possible.

Education and Training

If prevention of potentially problematic damp indoor environments is to be achieved, public education and training of professionals will be integral parts of the solution.

Education and outreach to citizens—especially those in vulnerable communities—could have a large role in preventing or limiting the future effects of damp indoor environments. The research and demonstration projects referred to above that included education and training components are examples of how this might be accomplished in targeted, intensive interventions. Most efforts undertaken to date, however, have been simply the provision of information. Several federal agencies—including EPA (EPA, 2002), the Federal Emergency Management Agency (FEMA, 2003), and HUD and the U.S. Department of Agriculture (Healthy Homes Partnership, 2003)—have, for example, published guidance on identifying and remediating problematic dampness and mold in the home. Some states, including Minnesota (MDH, 2003), and such cities as New York (NYCDOH, 2002) also provide dampness-remediation information on their health-department Web sites. However, the committee did not identify any assessments of public awareness of such information, its distribution outside households with Internet access, or its diffusion to individuals concerned with dampness or mold problems.

Chapter 2 notes that although technical information on controlling moisture in residences and larger buildings has been developed and published (Lstiburek, 2001, 2002; Lstiburek and Carmody, 1996; Rose, 1997), anecdotal experience suggests that architects, engineers, facility managers, and contractors in the building trades often do not apply it when designing, constructing, or maintaining buildings. The chapter recommends that these building professionals receive better training on how and why dampness problems occur and on their prevention. The committee specifically recommends that a curriculum be developed for the training of building inspectors so that they can identify and require correction of common construction errors that lead to dampness problems; the curriculum should be disseminated broadly.

At the time this report was completed (late 2003), the mold assessment and remediation industry in the United States was largely nonregulated; laws regarding specific standards for education and training of practitioners were just coming into effect in Louisiana (Act 880; effective August 15, 2003) and Texas (HB 329; effective September 1, 2003). In the absence of government standards, a number of groups have created “certifications” with widely varied requirements for instruction, testing, and continuing education. The committee did not undertake to evaluate them.

Many allergy and pulmonary-medicine specialists (especially those practicing in areas with large agricultural populations) have experience in deal-ing with patients who have experienced adverse health effects due to exposure to mold, endotoxin, or organic dust. In general, however, physicians and other health-care providers are not well educated in the diagnosis and treatment of environmental health-related problems (IOM, 1995). Recognizing that, the IOM Committee on Curriculum Development in Environmental Medicine (IOM, 1995) identified five competence objectives related to the clinical management of patients, stating that graduating medical students should

  • Understand the influence of the environment and environmental agents on human health based on knowledge of relevant epidemiologic, toxicologic, and exposure factors.
  • Be able to recognize the signs, symptoms, diseases, and sources of exposure relating to common environmental agents and conditions.
  • Be able to elicit an appropriately detailed environmental exposure history, including a work history, from all patients.
  • Be able to identify and access the informational, clinical, and other resources available to help address patient and community environmental health problems and concerns.
  • Be able to discuss environmental risks with their patients and provide understandable information about risk-reduction strategies in ways that exhibit sensitivity to patients' health beliefs and concerns.

Such proficiency clearly would be of benefit in addressing health issues that might be related to indoor dampness. The committee is aware that guidance to physicians on the recognition and management of health effects related to indoor mold exposure was being developed when this report was completed, but there were no publicly available documents for its review.

Public health professionals, particularly those who work in environmental health, will increasingly be required to assist in drafting recommendations for the prevention of excessive building dampness and the implementation of interventions to eliminate microbial contamination in affected buildings. It follows that their training should develop competence in the recognition of and appropriate response to problematic indoor dampness in workplace settings and in housing. Public health departments should assist in the development of educational campaigns to alert members of the general public to the risks associated with indoor dampness.

Environmental health is identified as a core component of public health education (IOM, 2003), and some courses related to indoor dampness and mold have been accredited for continuing education for public-health and industrial-hygiene professionals. Awareness of the possible health implications of damp indoor spaces in the public-health community has not, however, been examined.

Education is a common component of public-health interventions because it is relatively inexpensive and, at least in some circumstances, has been shown to be effective. A great deal of information is at least potentially available to citizens and to the various health and building professionals whose work is related to indoor environments, but little research has been conducted to evaluate whether it is reaching the right people or affecting their responses to possibly problematic dampness in buildings. The committee recommends that such research be conducted. Those formulating public-health interventions should examine asthma-education efforts, which may yield clues to effective strategies for communicating information on environmental health risks and effecting favorable changes in subjects' behavior. Any efforts undertaken need to include rigorous assessments of their short-term and long-term impacts. Six aspects of such education efforts merit attention:

  • Do they raise awareness of potentially problematic conditions and exposures?
  • Are they culturally and linguistically appropriate?
  • Are they reaching vulnerable populations—those that are at high risk for dampness problems or adverse health outcomes?
  • Do they effect changes in behavior that result in decreases in exposure or risk?
  • Are changes sustained?
  • Do the efforts address the possible role of the media and local and community-based organizations or institutions (such as schools and churches) in raising public awareness?


Implementation of the recommendations in this report will require collaboration with and among stakeholders in public health. Health departments, housing authorities, policy-makers, insurers, community-based organizations, and voluntary agencies will need to coordinate efforts to advocate for and effect the research efforts and changes in policy proposed here.

At least two collaborative approaches seem reasonable for introducing or furthering the prevention and control of damp indoor environments. The first is to integrate, or better integrate, dampness considerations into current efforts. HUD's Healthy Homes Initiative—which focuses on “researching and demonstrating low-cost, effective home hazard assessment and intervention methods, as well as on public education that stresses ways in which communities can mitigate housing-related hazards” (HUD, 2003b)—is one vehicle for promoting strategies that emphasize prevention of dampness. Another is the many respiratory-health-related, communitywide coalitions in the United States. A 2000 survey identified 63 asthma coalitions of varied size and resources (ACCP, 2000), and there were about 150 such organizations across the United States at the end of 2003 (Allies Against Asthma, 2003). Chapter 5 notes that the scientific literature supports an association between dampness and asthma exacerbation; it is appropriate to integrate dampness initiatives into coalition-led programs that do not have them.

A second approach is to develop new communitywide partnerships to address the specific prevention of potentially problematic damp indoor environments. Some aspects of dampness and the exposures that it promotes are unrelated to asthma or respiratory disease. It is possible and perhaps desirable to form collaborations that bring the stakeholders (including occupants and tenant organizations) together and focus them on effective actions in their mutual interest. Mobilization of stakeholders and communitywide approaches may be particularly important in low-income areas, where resources are scarce. The new partnerships may attract stakeholders not usually evident in community health-related endeavors—for example, building professionals—who can lend new perspectives to efforts to affect change.


On the basis of the review of the papers, reports, and other information presented in this chapter, the committee has reached the following findings and recommendations and has identified the following research needs regarding the public-health dimension of damp indoor environments. Preceding chapters of this report provide the foundation for some the recommendations and offer additional observations on health, building, and prevention and remediation issues.


  • Excessive indoor dampness is a public-health problem: dampness is prevalent in residential housing in a wide array of climates; sufficient evidence of an association exists between signs of dampness and upper respiratory tract symptoms, cough, wheeze, and asthma symptoms in sensitized persons; and sufficient evidence of an association exists between signs of mold and upper respiratory tract symptoms, cough, wheeze, asthma symptoms in sensitized persons and hypersensitivity pneumonitis in susceptible persons.
  • In the absence of a generally accepted definition of dampness or what constitutes a “dampness problem,” the advice offered in remediation guidelines developed by government and well-established professional associations can serve as references for when and what level of response is appropriate.
  • Indoor dampness has an economic dimension. Economic factors may encourage poor building design and construction practices; they may also create incentives to forgo or limit investment in maintenance and other measures that might help to prevent or reduce moisture problems. Cost-effectiveness studies are needed to assess the savings that damp-building prevention or remediation might generate.
  • An appropriate public health goal should be to prevent or reduce the incidence of potentially problematic damp indoor environments, that is, environments that may be associated with undesirable health effects, particularly in vulnerable populations. However, there are serious challenges associated with achieving that goal, given the lack of information on key scientific questions regarding the health effects of dampness-related agents, and questions of exposure and dose.

Recommendations and Research Needs

  • CDC, other public-health-related, and building-management-related funders should provide new or continuing support for research and demonstration projects that address the potential and relative benefit of various strategies for the prevention or reduction of damp indoor environments, including data acquisition through assessment and monitoring, building code modification or enhanced enforcement, contract language changes, economic and other incentives, and education and training. These projects should include assessments of the economic effects of preventing building dampness and repairing damp buildings and should evaluate the savings generated from reductions in morbidity and gains in the useful life of structures and their components associated with such interventions.
  • Carefully designed and controlled longitudinal research should be undertaken to assess the effects of population-based housing interventions on dampness and to identify effective and efficient strategies. As part of such studies, attention should be paid to definitions of dampness and to measures of effect; and the extent to which interventions are associated with decreased occurrence of specific negative health conditions should be assessed when possible.
  • Government agencies with housing-management responsibility should evaluate the benefit of adopting economic-incentive programs designed to reward actions that prevent or reduce building dampness. Ideally, these should be coupled with independent assessments of effectiveness.
  • HUD or another appropriate government agency with responsibility for building issues should provide support for the development and dissemination of consensus guidelines on building design, construction, operation, and maintenance for prevention of dampness problems. Development of the guidelines should take place at the national level and should be under the aegis of either a government body or an independent nongovernment organization that is not affiliated with the stakeholders on the issue.
  • CDC and other public-health-related funders should provide new or continuing support for research and demonstration projects that:
    • —Develop communication instruments to disseminate information derived from the scientific evidence base regarding indoor dampness, mold and other dampness-related exposures, and health outcomes to address public concerns about the risk from dampness-related exposures, indoor conditions, and causes of ill health.
    • —Foster education and training for clinicians and public-health professionals on the potential health implications of damp indoor environments.
  • Government and private entities with building design, construction, and management interests should provide new or continuing support for research and demonstration projects that develop education and training for building professionals (architects, home builders, facility managers and maintenance staff, code officials, and insurers) on how and why dampness problems occur and how to prevent them.
  • Those formulating the education and training programs discussed above should include means of evaluating whether their programs are reaching relevant persons and, ideally, whether they materially affect the occurrence of moisture or microbial contamination in buildings or occupant health.


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The calculation is based on a July 1996 population estimate of 5,105,230 and a January 1996 exchange rate of 4.4425 markkaa per U.S. dollar (CIA, 1997).


A more general examination of housing and health is outside the scope of this report. However, house dust mites, respiratory viruses, and cockroaches—all of which are associated with damp conditions—may have an important effect on occupant health (IOM, 1993, 2000). The literature also addresses how temperature acts as a contributory and independent risk factor for increased morbidity and mortality in damp indoor environments, especially among the elderly and poor (Evans et al., 2000; Healy, 2003; Mercer, 2003).


Periodic inspections of rental properties and public housing for mold were proposed as part of the U.S. Toxic Mold Safety and Protection Act of 2003 (the Melina Bill); HR 1268, 108th Congress, 1st session. However, the version of this legislation introduced on March 13, 2003, did not include provisions for compiling the information gathered in these inspections.


In 1995, participants in a workshop on indoor air convened by the American Thoracic Society decried the lack of venues where professionals working in the field could interact. They recommended that the Society and the American Lung Association “take the lead in conducting regular interdisciplinary workshops that promote in-depth discussion of key and timely issues” (ATS, 1997).


Floor dust loading, roach activity, and a composite measure of exposure to asthma triggers also decreased significantly in the high intensity group. It must be remembered that all of these environmental factors are thought to affect asthma outcomes and that the high intervention group also changed several behaviors thought to influence asthma exacerbation. The authors did not attribute the improvement in health outcomes to any one factor.

Copyright 2004 by the National Academy of Sciences. All rights reserved.
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