mopdf.com

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.Health Committee and Standing Standard Project Committee (SSPC) 62.1, Ventilation.Finally, the publications referenced above and this report were written withcommercial buildings, schools, and multifamily high-rise residential buildings astheir primary focus. However, as readers can appreciate by reading the epidemiological studies of building occupants referenced in this report, the warning signsof health-relevant indoor dampness and the principles of avoiding those conditions also apply to low-rise residential housing.Damp Buildings, Human Health, and HVAC Designv

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.Summary and RecommendationsEpidemiological researchers have shown clear and consistent associationsbetween occupancy of damp indoor spaces and increased probability of importantadverse health effects such as development of new asthma, exacerbation of existing asthma, allergic rhinitis, and respiratory infections1 (IOM 2004; WHO 2009;Mendell et al. 2011; Miller 2011; Kennedy and Grimes 2013; Miller and McMullin 2014; Kanchongkittiphon et al. 2015; Mendel and Kumagai 2017). Unlikesome other health risks, illnesses triggered by damp indoor spaces are preventable.In response to ASHRAE Position Document on Limiting Indoor Mold andDampness in Buildings (ASHRAE 2018), ASHRAE’s Technical Activities Committee (TAC) authorized the creation of this multidisciplinary task group todevelop a simple and easily recognizable description of dampness that is sufficientto increase the probability of negative health effects and to suggest practical, quantitative tools and techniques that can alert managers to the risk of a building or anindoor space becoming “damp” to an extent that it will affect health in the future.Toward these ends, this task group has reached consensus recommendationsfor a description of health-relevant indoor dampness and for quantitative tests andthresholds that can serve as early warning signs of possible health-relevant dampness in the future. These include health-relevant indoor dampness, quantitativemetrics, and dampness leading to structural risk.Health-Relevant Indoor DampnessIndicators of health-relevant indoor dampness in a building or space includevisible mold growth, moisture, damage from water or moisture, or musty/moldy/earthy odors. These indicators have each been clearly and strongly associated withincreased probability of negative health effects for occupants, although no specificdampness thresholds have been established and not all individuals are equallyaffected.Quantitative MetricsQuantitative metrics, with thresholds that separately provide early warning ofpossible future health-relevant dampness, are as follows:1. Evidence from epidemiological studies showed indoor dampness or mold were consistently associated with increases in multiple diseases (asthma development, asthma exacerbation, current asthma,never-diagnosed asthma, respiratory infections, allergic rhinitis, eczema, and bronchitis) and symptoms (lower respiratory symptoms such as difficulty breathing and wheezing as well as upper respiratory tract symptoms such as nasal, sinus, and throat symptoms and cough) (Mendell et al. 2011).Damp Buildings, Human Health, and HVAC Design1

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.1. Persistent water activity levels above 0.75 at the surfaces of organicmaterials or coatings.2. Persistent moisture content above 15% wood moisture equivalent(WME) in organic materials, coatings, and untreated paper-faced gypsum board.3. Persistent moisture content above 90% equilibrium relative humidity(ERH) in concrete or masonry that is either coated with—or is in contactwith—organic materials or coatings.4. Persistent indoor humidity above a dew-point temperature (DPT) of60 F (15 C) for buildings that are being mechanically cooled or above aDPT of 45 F (7 C) for heated buildings in moderately cold and mixedclimates (in international climate zones 4 and 5, as referenced in TableB1-4 of ANSI/ASHRAE/IES Standard 90.1 [ASHRAE 2019b]).In this context, the word persistent means that the condition has become typical because it extends for days or weeks at a time rather than being infrequentexcursions of a few hours per week above these suggested thresholds followed bya return to normal levels of dryness.Note that any of these quantitative metrics are indicators of abnormal conditions that can ultimately lead to moisture accumulation and health-relevant indoordampness. The word abnormal is used here to describe conditions that, while theymay occur with some regularity in many buildings, are seldom if ever the basis ofdesign for durable buildings and energy-efficient climate-control systems.Finally, note also that these quantitative metrics and thresholds are notintended to be, nor have they been documented to be, indicators of current healthrelevant indoor dampness. Unless or until such associations are established anddocumented, these quantitative metrics should be considered early warnings ofpossible health-relevant dampness at some future date. They do not provide quantitative validation of current health-relevant dampness.Dampness Leading to Structural RiskThis report deals with the issue of dampness as it relates to human health. Butthe committee notes that excessive indoor dampness has also been documented toreduce the load-bearing capacity of wood framing. Further, extended dampness orperiodic condensation can corrode critical structural fasteners inside the walls,foundation, and roof of a building.Under those circumstances, problems associated with excessive indoor dampness go far beyond long-term health effects, extending all the way to the risk ofshort-term structural failure. A thorough discussion of structural risks is beyondthe scope of this committee’s assignment, but we note the importance of limitingmoisture accumulation and avoiding condensation not only inside the building butalso inside the assemblies of its exterior walls, foundation, and roof. Prudentbuilding design, construction, and management must avoid interstitial condensation and moisture accumulation.2Damp Buildings, Human Health, and HVAC Design

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.Periodic moisture content measurements and/or continuous monitoring ofmoisture content and condensation inside building assemblies can help alert thebuilding owner, allowing action to avoid problems that could proceed to the levelof structural failure, with its obvious and significant risks to public health andsafety.Damp Buildings, Human Health, and HVAC Design3

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.Epidemiological Studies of Damp BuildingsOur task group notes that persistent dampness is not a normal indoor condition. Indoor spaces and furnishings are designed, constructed, and operated to bedry and to stay dry. If an indoor space has become damp enough to grow visibleamounts of mold, or to create musty/earthy odors, or to have visible water damageor moisture, something about the way the building is designed, constructed, operated, or maintained is simply wrong. The sources and mechanisms that led to persistent dampness must be discovered and eliminated promptly to avoid increasedprobability of health risks to occupants.Foundation of the DescriptionThe description of the characteristics of health-relevant dampness is based onfield research by epidemiological investigators that shows clear relationshipsbetween these dampness/mold (D/M) indicators and negative health effects. Inaddition, investigations show a dose-response relationship between the amount ofthe D/M indicator and the probability of adverse health effects. As examples ofthis research, consider the evidence summarized in Figures 1 and 2. (Mendell andKumagai 2017; Kanchongkittiphon et al. 2015).Figure 1 summarizes findings from two quantitative summaries (Quansah etal. 2012; Jaakkola et al. 2013) of many studies. The first group of four columnsshows that, with any indicator of mold or dampness, the asthma odds ratioincreases to 1.3. In other words, the results show that the probability of developingasthma in previously unaffected occupants was about 30% higher in the presenceof any indicator of dampness or mold. Further, the probability of developing anyform of rhinitis increased by 110%, and the probability of rhinoconjunctivitis was70% higher.The fourth column grouping shows the association established by this researchbetween perceived dampness and negative health effects. We note, however, thatthe studies do not provide any means of quantifying the amount of perceiveddampness that was associated with those health effects.Figure 1 also shows that increases in probability indicated by the presence ofmold odor (column grouping 2) is greater than the risks associated with the otherindicators: visible mold growth, dampness, and water damage (column groupings3, 4, and 5). From evidence such as this, we conclude that professionals shouldnot dismiss moldy/musty odors as merely indicators of a potential future problem.Instead, those in a position to take action should recognize that odors are an indicator that the probability of negative health effects is already elevated.4Damp Buildings, Human Health, and HVAC Design

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.Figure 1Summarized findings from data described in two meta-analyses ofassociations between health effects and dichotomous scores fordampness/mold (D/M) indicators (results reported by Quansah et al. 2012and Jaakkola et al. 2013). Vertical bars show 95% confidence limits. Anodds ratio of 1.0 indicates no increased risk with the presence of the D/Mindicator; an odds ratios above 1.0 indicates increased probability of theheath effect. (Courtesy M.J. Mendell)Next, consider the elevated probability of health effects shown by the threefield studies summarized in Figure 2. In these studies, four easily perceptible indicators of dampness or mold were used to establish a dampness/mold (D/M) index:1. Visible mold2. Mold odor3. Current water damage4. History of visible mold or water damageThe researchers established three levels for their D/M index: none, low, andhigh. The criterion for an index score of none was that none of the four indicatorsof dampness or mold were present in the buildings examined. The general level ofnegative health effects for this group, without the presence of D/M indicators, wasconsidered the reference level, with an odds ratio of 1.0.The criterion for an index score of low was the presence of at least one of thefour indicators, but not as much as the surface area amount specified for an indexscore of high. The criterion for an index score of high was a total of either visiblemold greater than or equal to 0.2 m2 in one room or visible mold growth pluswater damage greater than or equal to 0.2 m2 on one surface (0.2 m2 2.15 ft2).To understand the implications of these results, consider the increase in oddsratio for upper respiratory infections (URIs) shown in Figure 2a (Biagini et al.Damp Buildings, Human Health, and HVAC Design5

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.Figure 2Summarized associations between health effects and three-level scores formold and dampness. Results from the Cincinnati Childhood Allergy and AirPollution Study (CCAAPS), as reported by Biagini et al. (2006) andIossifova et al. (2007, 2009). (Courtesy M.J. Mendell)2006). Researchers found approximately five times the odds of having a URI(400% increase in probability) in the presence of either visible mold greater thanor equal to 0.2 m2 in one room or visible mold growth plus water damage greaterthan or equal to 0.2 m2 on one surface (0.2 m2 2.15 ft2).Also note another important point about the findings shown in the three-column grouping for wheeze in Figure 2b (Iossifova 2007). The second and third columns in that set of three show that the odds ratios for developing wheezing amongall the children in the study at the low and high levels of dampness were 1.2 and4.4 (20% to 410% increase), compared to the first column (no dampness).But even far greater effects from dampness were seen among the children whowere atopic (allergic). These observations are shown in the third set of columnswithin Figure 2b. Note that the third set of columns, labeled “wheeze among atopics,” shows that odds ratios for wheezing increased between 2.6 and 42.5 times.Thus, in this sensitive population, even the low dampness level was associatedwith a 160% increase, and at the high dampness level the resulting probability ofwheezing was almost 10 times the probability of that negative effect (i.e., 42.5 vs4.5) compared to dampness effects on children who were not reported as beingallergic at the time of the investigations.From evidence such as this, we conclude that professionals should not dismissrelatively small amounts of mold growth in one or two parts of a building asmerely indicators of a potential future problem. Instead, those in a position to takeaction should recognize that even relatively small areas of visible mold or waterdamage (no threshold yet determined) and/or perceptible moldy odors are associated with large increases in probability of negative health effects, for at least somepercentage of the public.6Damp Buildings, Human Health, and HVAC Design

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.Factors that May Increase orReduce Dampness Health RisksWhile these epidemiological investigations clearly show elevated probabilitiesof negative health effects in spaces that have visible mold, water damage, or moisture or that smell moldy, we note that the research does not confirm equal probability for all people and all types of occupancies. Factors outside of ourrecommended description may also increase or reduce risks for specific buildingsand specific individuals, such as the factors discussed in the following subsections.ExposureThe peer-reviewed research that establishes a dose-response relationshipbetween the amount of moldy or water-damaged surface and the probability ofhealth risk was conducted mostly in residences rather than in commercial buildings. The number of hours, days, weeks, and years that an occupant is exposed todampness in a home, apartment, or bedroom is far higher than the amount of timeoccupants spend in hotels or airports, unless they are employees. When other factors are equal, dampness increases the probability of occurrence of respiratoryhealth problems from spaces where people spend more time, as shown by researchin both homes and offices (Park et al. 2004; Mendell and Kumagai 2017).Individual Occupant SensitivityClearly, hospital patients taking drugs that suppress their immune systems aremore sensitive to any health risk, including effects of building dampness. Similarly, infants, children, and the elderly have fewer defenses against environmentalinsults that most healthy adults may endure without obvious harm. Also, individuals who have allergic sensitivities are less able to endure an environment that others of similar age and health status might find less risky, as shown in Figure 2. So,all other factors being equal, it is reasonable to assume that individual sensitivityis an important factor in determining health risk, and to date, this sensitivity hasbeen difficult to quantify for specific individuals.Dampness Description is Based on the Precautionary PrincipleBased on the history of indoor air and mold investigations in North Americaand Northern Europe over the last 25 years, it is clear that not all occupants sharethe same probability for health risk in damp spaces. Further, some may elect toDamp Buildings, Human Health, and HVAC Design7

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.occupy spaces that elevate the probability for negative health effects. Adults areentitled to accept risk, absent any coercion of organizational or economic necessity, and assuming the individual is capable of informed consent, has beeninformed, and has in fact consented to the risk.But given ASHRAE’s stated mission, “to advance the arts and sciences ofheating, ventilation, air conditioning and refrigeration to serve humanity and promote a sustainable world,” we believe that the Society should inform the public offactors that we know increase the probability of negative health effects rather thanwaiting until we know the exact percentage of occupants that face that risk at eachlevel of personal sensitivity or waiting until we know the exact number of hours ofexposure that represent an increase in risks in each type of building.We recommend the description of health-relevant indoor dampness stated previously, based on the precautionary principle that obvious risk factors should beeliminated when they are known, even if all the mechanisms that lead to risk arenot fully understood.8Damp Buildings, Human Health, and HVAC Design

2020 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution,or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.Quantitative Tests with Early-Warning ThresholdsDelaying action until indoor spaces become damp is not in the public interest.Accordingly, building owners and operators need quantitative tools and tests thathelp them recognize the approach of future problems so they can prevent healthrelevant dampness before it occurs.But before considering the use of any quantitative tests and thresholds, readersshould keep in mind some important cautions about building dampness, beginningwith its dynamic bio-hygro-thermal variation over time, and the critical importance of the exact locations of measurements.The Importance of Measurements Over TimeThe real-world constraint

As a Society of volunteers, ASHRAE’s mission statement is broad and com-pelling: “To serve humanity by advancing the arts an d sciences of heating, ventila - tion, air conditioning, refrigerat ion and their allied fields .” Consequently, from the beginning of mold