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2 Background This chapter provides background information on several topics rel- evant to the consideration of the intersections of climate change, the indoor environment, and public health. They include the elements of climate- change research most relevant to the indoor environment, how the outdoor environment affects conditions indoors and how the indoor environment affects health, and the amount of time that people spend indoors. The chapter identifies the five major issues related to potential alterations in indoor environmental quality induced by climate change: air quality, damp- ness, moisture and flooding, infectious agents and pests, thermal stress, and building ventilation, weatherization, and energy use. It also addresses populations that are particularly vulnerable to health problems associated with indoor environmental quality. ELEMENTS OF CLIMATE-CHANGE RESEARCH RELEVANT TO BUILDINGS AND PUBLIC HEALTH The science of climate change is large and complex, and many details are outside the scope of the committee’s task. It therefore did not conduct an independent review of the voluminous literature regarding such subjects as the nature of changes in the earth’s climate in the short and long term and the potential magnitude of the changes. Instead, the committee drew on the research and conclusions contained in other National Academies reports—in particular, four in the America’s Climate Choices series (NRC, 2010a,b,c,d)—and peer-reviewed literature and assessments found to be authoritative by the committees responsible for those reports, such as the 33

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34 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC, 2007) and Global Climate Change Impacts in the United States (USGCRP, 2009). The overall conclusion of the National Academies report Advancing the Science of Climate Change was that climate change “poses significant risks for—and in many cases is already affecting—a broad range of human and natural systems” (NRC, 2010b, p. 1). The US Global Change Research Program, which coordinates and integrates federal climate change research, found (USGCRP, 2009, p. 9) that Climate-related changes have already been observed globally and in the United States. These include increases in air and water temperatures, re- duced frost days, increased frequency and intensity of heavy downpours, a rise in sea level, and reduced snow cover, glaciers, permafrost, and sea ice. A longer ice-free period on lakes and rivers, lengthening of the grow- ing season, and increased water vapor in the atmosphere have also been observed. Over the past 30 years, temperatures have risen faster in winter than in any other season, with average winter temperatures in the Midwest and northern Great Plains increasing more than 7ºF. Some of the changes have been faster than previous assessments had suggested. These climate-related changes are expected to continue while new ones develop. Likely future changes for the United States and surrounding coastal waters include more intense hurricanes with related increases in wind, rain, and storm surges (but not necessarily an increase in the num- ber of these storms that make landfall), as well as drier conditions in the Southwest and Caribbean. These changes will affect human health, water supply, agriculture, coastal areas, and many other aspects of society and the natural environment. Such findings are relevant to the committee’s work because conditions in the outdoor environment greatly influence conditions in the indoor environment. Literature Regarding Observations of Climate Change This report uses the term climate to refer to prevailing outdoor environ- mental conditions—including temperature, humidity, wind, precipitation, sea level, and other phenomena—and climate change to refer to modifica- tions in those outdoor conditions that occur over an extended period of time. Observations of key climatic variables provide a rich historical record of how the climate has changed in the past and serve as a basis for assessing potential future change (IPCC, 2007; NRC, 2010b; USCCSP, 2008). Measurements of global mean temperature indicate that the first decade of the 21st century was 0.8°C (1.4°F) warmer than the first decade of the

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35 BACKGROUND 20th century. Associated with that temperature rise have been observa- tions that heat waves have become longer and more extreme and that cold spells have become shorter and milder. For example, the western Europe heat wave of 2003 was responsible for upwards of 70,000 deaths and was the warmest summer there in more than 600 years (Robine et al., 2008). No single event like that can be reliably attributed to climate change, but it is consistent with expectations for the future. Within the United States, hot days, hot nights, and heat waves have become more frequent in recent decades and were the leading cause of weather-related morbidity and mor- tality during 1970–2004 (USGCRP, 2009). On an urban scale, the heat-island effect contributes to local tempera- ture increase. For example, the urban heat island around Phoenix, Arizona, raises minimum nighttime temperatures by as much as 12.6°F (7°C) (Brazel et al., 2000). When increased ozone events occur simultaneously with heat waves, mortality can rise by 175% (Filleul, 2006). As extremely hot days tend to be associated with high pressure and stagnant air-circulation pat- terns, ground-level ozone, PM2.5, particulate sulfate, and organic carbon have been found to correlate strongly in summer months (NRC, 2008). Measurements of rainfall indicate that moist regions of the globe are getting wetter and semiarid regions are becoming drier; this is consistent with an intensification of the hydrologic cycle. In situ and space-based pre- cipitation observations indicate that both global precipitation and extreme rainfall events are increasing. Total runoff is increasing but shows sub- stantial regional variability (cf. USGCRP, 2009). In the United States, the amount of precipitation falling in the heaviest 1% of rain events increased by 20% in the past century, and total precipitation by 7%. Over the past century, there was a 50% increase in the frequency of days with precipita- tion of more than 10 cm in the upper Midwest. Heavy rains can lead not only to flooding but to a greater incidence of sewage overflows, contami- nated drinking water, and waterborne diseases, such as cryptosporidiosis and giardiasis. Rivers and lakes are freezing later and thawing earlier with serious implications for flooding. The manner in which increased tempera- ture and decreased rainfall covary in the western United States has led to a 400% increase in western wildfires in recent decades (Westerling et al., 2006). Drought and possible changes in irrigation practices could induce more frequent windblown-dust storms, which constitutes an air-quality ef- fect with potential public-health consequences. Literature Regarding Projected Climate Change Observations like those summarized above needed to be supplemented with models that project potential conditions. Such predictions are essential

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36 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH for guiding policy because of the long lag times associated with changes in our built environments. Policy-makers need to be able to anticipate future change before it occurs to be able to plan appropriately. Projections of climate change are derived from the output of numerical models similar to the models used for numerical weather prediction albeit at coarser resolution. For day-to-day weather prediction, with a spatial resolution of tens of kilometers, the prediction is influenced by the initial conditions and the observed state of the atmosphere. In contrast, a climate projection of the general state of the atmosphere—global mean temperature over the next 100 years—is influenced by changes in the concentration of heat-trapping greenhouse gases and coupling of the atmosphere to the ocean, land surface, and cryosphere. At the time of the first Intergovernmental Panel on Climate Change (IPCC) assessment report in 1990, the best resolution of climate models was around 500 km; for the fourth IPCC assessment report (AR4) in 2007, the best resolution was around 100 km; and to support the fifth IPCC assess- ment, due in 2013, some climate-change models are being run at resolutions of tens of kilometers. The importance of greater and greater resolution means that future IPCC assessments will move away from global mean met- rics of climate change (such as temperature and sea-level rises) and toward a much greater emphasis on the anticipated changes at regional levels. As with spatial resolution, the climate projections run since 1990 have focused on the mean states of future climate for, say, a decade in the future, that is, 2089–2099. Because extreme climatic events often take place at the re- gional level on relatively short time scales, time and space become coupled. Hence, to simulate the change in extreme or high-intensity climate events, such as storms or floods, high resolution in climate models is a necessity, but it has been limited in the past by the capability of high-performance computing platforms. It must be remembered, though, that the usefulness of high-resolution models is limited by uncertainties in information supplied by the larger-scale models they depend on and the natural variability in the climate (USCCSP, 2008). The findings of the fourth IPCC assessment (2007) indicate that global average surface temperatures are projected to rise from the 1980–1999 av- erage by 1.1–6.4°C by the end of the 21st century. Global sea level will rise by 0.8–2 m by 2100. The effects of global sea-level rise will be exacerbated at the regional level along the eastern seaboard of the United States by a likely increase in the intensity of Atlantic hurricanes and resulting storm surge. Heat waves will become more intense, more frequent, and longer- lasting, and the frequency of cold extremes will continue to decrease. By 2100, the number of heat-wave days is expected to double in Los Angeles and quadruple in Chicago (USGCRP, 2009). The intensity of precipita- tion events is also expected to continue to increase and to result in more

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37 BACKGROUND frequent heavy downpours and floods, most notably in wetter regions, and droughts are expected to become more common in semiarid regions. That projected acceleration of the hydrological cycle suggests that rainfall will become more concentrated into intense events with longer, hotter dry periods between them. Implications for the continental United States are that the northern tier of states will become wetter with attendant increased runoff and that the southern states will become drier, especially in the West. In the face of those changing patterns of temperature, precipitation, and extreme events, the range and effects of pathogens and pests are also expected to change.1 Beyond anecdotal evidence and extrapolation, there has been little study of how climate change will influence the indoor environment from the perspective of adverse effects on human health. Given that climate-change projections with regional specificity are only now becoming available, that may not be surprising. However, the advent of climate-change projections on regional scales makes a number of types of research possible. In the future, the climate-modeling community will strive for higher and higher resolution of climate models by increasing the resolution of global models everywhere and by using the output of current global models as in- put into regional and urban models with downscaling techniques. The move from climate models to so-called Earth System Models—in which aspects of chemistry, biology, and ecosystem functioning are incorporated at the junc- tion of the physical climate system and biogeochemical cycling—represents the next grand challenge to the climate-science community (NRC, 2010b). ADVERSE EXPOSURES ASSOCIATED WITH CLIMATE-CHANGE– INDUCED ALTERATIONS IN THE INDOOR ENVIRONMENT Indoor environmental conditions exert considerable influence on health (ASHRAE, 2010; HHS, 2005, 2010), learning (NRC, 2006), and produc- tivity (Fisk and Rosenfeld, 1997; Mendell and Heath, 2005; NRC, 2006; Seppänen and Fisk, 2004). Fisk and Rosenfeld (1997) estimated that poor environmental conditions and indoor contaminants cost the US economy tens of billions of dollars a year in exacerbation of illnesses, allergenic symptoms that include asthma, and lost productivity. Research conducted by the US Environmental Protection Agency suggests that such indoor con- taminants as radon, secondhand smoke, and volatile organic compounds contribute to tens of thousands of excess deaths a year, with premature deaths from pollutants emitted indoors equivalent to the impact of outdoor particulate pollution (Mudarri, 2010). Reviews of the scientific literature by Institute of Medicine committees (2000, 2004) concluded that there 1 This topic is addressed in Chapter 6.

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38 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH was evidence of an association between new-onset asthma and indoor dampness, molds, and dust mites. The 2006 National Research Council report Green Schools: Attributes for Health and Learning concluded that moisture problems, inadequate ventilation, and airborne contaminants in public schools contribute to suboptimal learning and absenteeism among teachers, administrators, and students. Indoor environmental quality is a function of four general factors: mac- roenvironment, building infrastructure, occupant furnishings and activities, and occupant health and perceptions. These factors are detailed below. Macroenvironment factors include such items as outdoor pollution, climate and weather conditions, and soil conditions, including geologic features that affect the risk of radon emission. With reference to climate change, the confluence of extreme precipitation events, impermeable sur- faces, and soil conditions influences the effect of water on structures. How water is managed around buildings and the integrity of a structure will help to determine moisture transport and its effects on indoor environments. Building infrastructure and building component systems have both di- rect and indirect influences on indoor contaminants. Indoor environmental quality is a function of the interrelationships of a building’s foundations; floors, walls, and roofs; heating, ventilation, and air-conditioning (HVAC) systems; electric and plumbing systems; materials; and furnishings. The building envelope’s tightness or porosity; the integrity of foundations, roofs, and windows; and other planned and unplanned openings all influence the infiltration of outdoor moisture and air pollutants. Studies estimate that about half the outside air that enters even a mechanically ventilated build- ing finds its way in through unducted pathways (Persily, 1997). Building ventilation systems provide conditioned air and dilute inter- nally generated contaminants. HVAC systems, for example, affect a variety of indoor environmental factors, including pollutant levels, temperature, humidity, noise, air quality, moisture control, and odors. The location of air intakes, the efficiency of ventilation filters, and operating practices all affect the amount and quality of outdoor air used to ventilate indoor spaces. The optimum size and capacity of an HVAC system depend on the orientation of the building, the total floor area, the quality of insulation, the number of windows, and other factors. Other components, such as plumbing and electric systems, often create penetrations between floors that contribute to unplanned pathways for contaminant movement. There are numerous other examples of interrelationships between the design and operation of a building system and its indoor environmental quality. Generally speaking, indoor environmental quality deteriorates if buildings are not properly designed, systems are not operated appropri- ately, or needed maintenance and repairs are not performed or are deferred (NRC, 2006).

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39 BACKGROUND Structural features (foundations, façade, thermal bridges, roof design, and the like), details of construction specifications, and integrity of con- struction can also influence indoor conditions. Those elements affect the bulk, capillary and vapor transport of water, and passive or active move- ment of air through the structure. Occupant furnishings and activities play a central role in influencing indoor conditions, initially through design and specifications of building systems and materials. Occupants, owners, facility managers, purchasing agents, interior designers, and others make many decisions about furnish- ings, decorative materials, cleaning products, appliances, and equipment that can emit particles and gases into the interior of buildings. Occupants make myriad choices related to product use, maintenance of products, equipment, and appliances and undertake actions that influence ventilation and hence contaminant concentrations and moisture. “Sick-building” inves- tigations have shown indoor problems related to materials’ off-gassing (of formaldehyde, for example) that, in some cases, was precipitated or aggra- vated by other factors related to design, operation and use, or maintenance (Oliver and Shackleton, 1998; Šeduikytė and Bliūdžius, 2003; Seppänen and Fisk, 2004). Occupant health and perceptions, which influence susceptibility and response to contaminant exposures and indoor conditions, are perhaps the most complicated component of indoor environmental quality because of the inherent variability in human expectations and vulnerabilities. The variability makes it difficult to draw inferences from scientific research for codification in ventilation, comfort, material performance, and health stan- dards in the many different types of indoor environments. Climate Change Concerns for Indoor Environments and Possible Health Risk This report examines the influences that changing weather patterns and shifting climate regimes may have on factors that affect indoor envi- ronments and the health of occupants. Figure 2-1 illustrates how climate- change–induced scenarios could affect building operations and indoor environments and possibly lead to human health effects through exposures to physical, chemical, and biologic stresses. Several of the scenarios involve moisture intrusion into buildings directly or as a result of condensation. Prolonged heat waves will heat the thermal mass of structures to the extent that the radiant-heating component will become more important indoors. Warmer ambient environments will mean more air-conditioning use in buildings, which in turn alters ventilation and dew points within structures. Climate change models project increases in hydrocarbon emissions and

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40 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH Potential direct and Potential impacts on the Potential impacts on health indirect consequences indoor environment of climate change Increased mortality and Change in loads on HVAC decreased productivity Increased incidence of systems from temperature extremes extreme temperature Increased energy Altered infectious events consumption respiratory disease transmission Exposure to chemical Damage to and degradation emissions from damaged of building materials Increased incidence of materials hurricanes and other extreme precipitation Water and vectorborne events in some locations diseases Flooding and water damage Higher sea levels Dampness/mold associated Displaced persons during symptoms or illness evacuations Physical and psychologic Increased incidence of stress from displacement drought in some locations Increased airborne Respiratory distress and particulates from crustal Increased incidence of illness dust and combustion wildfires Possible changes in irrigation practices Increased indoor Respiratory distress and ozone levels illness Increased outdoor Increased release of other ozone levels Other distress and illnesses pollutants from ozone- from chemical exposures initiated chemistry Increased outdoor Allergen-mediated distress Alterations in indoor pollen levels and illness allergen levels Changes in geographic Distress and illnesses from Greater use of pesticides ranges of pests pesticide exposures More frequent Loss of mechanical Exposure to excessive interruptions in electrical ventilation heat or cold power from extreme weather events or Loss of mechanical cooling Exposure to CO from overstressing of the or heating back-up electrical generators electrical grid FIGURE 2-1 Possible pathways by which climate change could affect the indoor environment and health (adapted from Su, undated). Figure 2-1 NEWER.eps

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41 BACKGROUND concomitant increases in outdoor ozone concentrations. They, in turn, have implications for ozone penetration indoors and later chemical reactions. The committee organized its examination of the literature regarding potential alterations in indoor environmental quality induced by climate change into five primary categories: air quality; dampness, moisture and flooding; infectious agents and pests; thermal stress; and building design, construction, operation, maintenance, and retrofitting. The divisions are in some respects arbitrary—for example, damp spaces provide a hospitable environment for some pests and infectious agents and thus affect air qual- ity—but they are a means of rationalizing a complex set of circumstances that influence the health of building occupants. Chapters 4–8 address the science regarding them. TIME SPENT IN THE INDOOR ENVIRONMENT Exposure is a function of pollutant levels and the time spent in contact with the pollutants. Several studies have examined where people spend their time, how long they are in those environments, and, in some cases, the ex- tent of their physical activity in the environments. An understanding of the amount of time that people spend indoors and the variations in different segments of the population is central to the evaluation of the risks associ- ated with potential alterations in indoor environmental quality induced by climate change. Information on time spent in particular environments is also relevant to developing strategies to reduce problematic exposures and in turn to improve health. The majority of people’s time in the United States is spent indoors, whether in residences, in schools, or in workplaces. According to the 1994 National Human Activity Pattern Survey, the average person spends just over 92% of his or her time indoors; of that time indoors, almost 70% is spent in one’s residence (Klepeis et al., 2001). Care must be exercised in generalizing from that, inasmuch as some studies include time spent in ve- hicles—typically 4–6% of the day—in accounting for indoor time (Dales et al., 2008; Klepeis et al., 2001; Leech, 2002; Zhang and Batterman, 2009). Researchers have also examined the time spent indoors in other coun- tries. In a 1998 study in Italy, it was found that people spent 84% of their time indoors, with 64% of that time at home and 3.4% in vehicles (Simoni et al., 1998). Another study in different cities representing the seven re- gions of Europe found that people spent 90% indoors—58% at home, 25% at work, and 7% in vehicles and other indoor public environments (Schweizer, 2007). Studies in Canada found that about 89–90% of time is spent indoors (Kim et al., 2005; Wu et al., 2007). Even more striking, those in New Zealand tend to spend ~94% indoors, 5% of it in transit (Baker et al., 2007).

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42 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH When different regions and times of the year were looked at, few dif- ferences were noted in how the average adult spent his or her time. For time spent indoors in residential environments, no significant difference was found between the northeastern, midwestern, southern, and western regions of the United States (EPA, 1996; Klepeis et al., 2001). On the average, people were in their homes 69.4–70.7% of the time (EPA, 1996; Klepeis et al., 2001). Similarly, the time of the year only showed a small difference: 67.9% of the time was spent indoors during spring and 71.9% in winter (EPA, 1996). The one variation was between weekdays and weekends: the mean time spent in residences during weekdays and weekends was 67.1% and 74.6%, respectively (EPA, 1996). It appears that adults living across all US Census regions tend to spend about 6% of their day in vehicles, with little contrast between the seasons (EPA, 1996). In contrast with time spent in residences during the weekdays and weekends, there was no difference in time spent in vehicles (EPA, 1996). Children, particularly young children, spend a large fraction of their time indoors. Children under 2 years old tend to spend the most time in- side, just under 94% (Cohen-Hubal et al., 2000; EPA, 2009). Time spent indoors continued to be 83–94% throughout childhood, including 19% in school (EPA, 1996, 2009). Younger children tended to spend more of their time at home than older children but only during the traditional school year (Silvers, 1994). It is necessary to note that older children are not necessarily spending more time outdoors when they are not at home; in fact, they often are spending more time in the school environment (Silvers, 1994). During summer, younger children were more apt not to spend time at home and older children more apt to spend time at home (Silvers, 1994). There has been a trend toward students’ spending less time in school and participating less in sports and other outdoor activities than 30 years ago (Juster et al., 2004). In 1981, children spent about 75 min/day outdoors (Juster et al., 2004) while in 2003, they spent only 50 min (Juster et al., 2004). That shift is peculiar to children: time spent indoors not only has increased slightly but has shifted between time spent in the residence and time spent in other indoor facilities. In adults, however, time spent indoors has remained constant over the past several decades (Klepeis, 2001). A cohort study performed in New York, New Jersey, Pennsylvania, Washington, Oregon, and California looked at seasonal differences. It found that children 5–12 years old increased their time spent indoors only in summer (Silvers et al., 1994). One interesting point is that that did not vary from one region to another (Klepeis et al., 2001; Silvers et al., 1994). The elderly tend to spend more time indoors, particularly in their resi- dences, than do their younger counterparts (Berry, 1991; Franklin, 2004; Geller and Zenick, 2005; Kenney and Munce, 2003; Klinenberg, 2002).

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43 BACKGROUND TABLE 2-1 Percentage of Time Spent Indoors as a Function of Age Fraction of Time Spent Fraction of Total Time Spent Population, age in years in Residence, % Indoors General populationa 69 86.5–91.6 Children and youthb Birth to <1 75.7 94 1 – <2 72.7 94 2 – <3 67.3 91.4 3 – <6 66.0 88.8 6 – <11 60.6 83.4 11 – <16 60.8 87.5 16 – <21 56.9 86.6 Elderly (>64)c 81.6–95 a Bernstein (2008), Dales (2008), Klepeis (2001). b EPA (2009). c Berry (1991), EPA (1996). Table 2-1 summarizes information on time spent indoors in the United States as a function of age. Some researchers have suggested that shifts in ambient conditions due to climate change will lead to people spending more time indoors (Bluyssen, 2009; Samet, 2009). This is plausible, given that sheltering indoors is a common response to extreme weather conditions such as high heat. How- ever, the lack of regional differences in time spent indoors in the United States suggests that adaptation also plays a role in this decision and insuf- ficient information exists to draw confident conclusions about whether and how such factors will influence future behavior. CLIMATE CHANGE AND VULNERABLE POPULATIONS Segments of the population will vary in their ability to adapt to climate change–induced alterations in the indoor environment, depending on their circumstances. This section addresses a number of factors that might influ- ence whether particular populations are more vulnerable to adverse effects. Vulnerability relates to the balance between susceptibility factors and factors that increase the resilience of populations to environmental stressors (Balbus and Malina, 2009). It is a dynamic characteristic and can include the geographic region in which one resides and the adaptive capacity of an individual, including the presence of chronic medical conditions, low socioeconomic conditions, infancy or old age, and living in an isolated or segregated area (Shonkoff et al., 2009). Racial and ethnic minorities may be at great risk for health conditions related to climate change.

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44 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH Kelly and Adger (2000) write that a person’s vulnerability is determined by access to resources and the diversity of income sources and by social status of the person or the person’s household in the community. The abil- ity of a person to adapt is influenced by intrinsic factors (such as age and health) and extrinsic factors (such as housing and the availability of and ability to go to shelters during extreme weather events). Poverty is therefore an important indicator of individual vulnerability to climate change and is related to marginalization and lack of resources. Poverty affects vulnerabil- ity through people’s expectations of the effects of hazards and their ability to marshal resources to alleviate risks. Chapter 7 addresses the literature on the role that biologic vulnerabil- ity and economic and social circumstances play in determining the risk of health effects of exposure to heat. Several other aspects of climate change’s effects on the indoor environment might also affect various segments of the population disproportionately. Susceptibility to such changes as increased incidence of extreme weather events, high humidity, and expanded ranges of some pests can be expected to be influenced by physiologic factors. Biologic sensitivity may be related to a person’s developmental stage, pre-existing chronic medical conditions, acquired factors (such as immunity), and genetic factors (such as metabolic enzyme subtypes that play a role in sensitivity to toxic sub- stances) (Balbus and Malina, 2009). Children have been shown to be more vulnerable to the effects of exposure to a number of indoor chemicals as a result of their metabolic rates, body size, behaviors, immature immune responses, and still-developing ability to detoxify substances (Faustman et al., 2000). Human and experimental studies show that the fetus and infant are more sensitive than adults to many environmental toxicants, includ- ing residential pesticides (Perera et al., 2005; WHO, 1986; Whyatt et al., 2004). In addition, some types of medications—including antipsychotic, antiparkinsonian, and anticholinergic drugs—may increase vulnerability to environmental insults (Brown and Walker, 2008; Kenny et al., 2010; Luber and McGeehin, 2008; WHO, 2004). Increasing temperatures and increasing humidity associated with cli- mate change are expected to result in changing patterns of insects and rodents. People in multifamily urban dwellings where pesticides are com- monly used may be at increased risk for exposure and have little control over the pesticides that might be used in their buildings. Children and pregnant women will be most vulnerable to the health consequences of pesticide exposure. Pesticides sprayed outdoors can also find their way indoors through air exchange or be brought in on clothing, on skin, and especially on shoes. People living close to agricultural operations may also be at particularly high risk. Homes in low-income areas tend to have greater occupant density,

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45 BACKGROUND which exposes more people to pollutants in the indoor environment. Al- though one study found that type of building material did not increase vulnerability to climate change (Kovats and Hajat, 2008), other research indicates that brick homes that have high thermal mass and top-floor apartments that have poor ventilation and closed windows are associated with increased mortality during heat waves relative to other buildings (Mirchandani, 1996; Vandentorren et al.; 2006). Older homes that have poor insulation and poor ventilation may expose families to increased risk from water events, rising humidity, and pest infestation. Low-income homes tend to be older, and this could be associated with “leakier” home environments and more contamination with outside pollutants (Chan et al., 2005). Leakier homes could also be at greater risk for water damage and infestation with rodents or insects. Some studies have found that multi- family units are not necessarily “leakier” but instead have lower rates of ventilation, which could increase the risk of health effects of exposure to indoor sources of pollutants (Zota et al., 2005). Home ownership also has an influence on occupant health, with home owners reporting better health status and better health outcomes than renters (Kuh et al., 2002; Pollack et al., 2010; Robert and House, 1996; Wadsworth et al., 1999). There are several potential reasons for this; most centered on differences in wealth and socioeconomic status. Renting may leave less disposable income for health care. Renters tend to have lower incomes than homeowners, and a larger percentage of renters’ incomes tend to be allocated to rent than homeowners’ incomes are allocated to mortgages. Minorities and those with lower incomes are more likely to rent than own, and those who had difficulty paying rent and utility bills were less likely to seek out medical care when needed (Kushel et al., 2006). Neighborhoods with high levels of homeownership tend to be neigh- borhoods with higher wealth and socioeconomic status, thus also influ- encing the physical condition of the housing unit based on neighborhood conditions (Kearns et al., 2000; RWJ, 2008). The American Housing Survey found that older tenants tend to live in more expensive, yet lower quality housing than their home-owning counterparts (Muller et al., 2001). Additionally, renters are at a disadvantage in that they have less control over modifications made in their residences. If the owners delay or ignore requests for improvements to the housing unit, the tenants are left with little recourse (Pynoos and Nishita, 2003). Homeowners are also more likely to take precautionary measures against possible health hazards, which may be in part due to longer length of time spent residing in the same housing unit and the larger financial investment placed in the home. This is seen most prominently in the case of radon. The National Health Interview Surveys in 1994 and 1998 found

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46 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH that radon awareness and testing differed between homeowners and renters (Larsson et al., 2009). Those who owned a single family home or town- home were more likely to have heard of radon and to get their homes tested than those who rented apartments or condos (Larsson et al., 2009). And, a survey of New York residents found that homeowners were more likely to perform radon mitigation actions than renters (Wang et al., 1999). Having homeowner’s or renter’s insurance allows families to adapt to events associated with climate change. Insured families whose homes expe- rience water damage can obtain repairs quickly whereas uninsured families are forced to vacate their homes or live in substandard, damp environments for long periods. In general, the poorest households are most likely to have the poorest air quality, whether because of a lack of air conditioning or be- cause they are underinsured with respect to repairing damage from climate- change–related moisture (Fothergill and Peek, 2004; Thomalla et al., 2006). Studies indicate that there are regional differences in health outcomes (Fisher et al., 2009; Halverson et al., 2004). Balbus and Malina (2009), who focused their analysis on potentially vulnerable populations for climate change health effects, assert that populations in certain parts of the United States may experience “increased risks for specific climate-sensitive health outcomes” and that “[s]ome regions’ populations may in fact experience multiple climate-sensitive health problems simultaneously.” The researchers offered four examples—locations of past hurricane landfalls, past extreme heat events, high concentrations of population 65 years of age or older, and cases of West Nile virus—to illustrate how geographic, demographic, and climatic factors might influence regional vulnerabilities. The 2010 Na- tional Academies report Adapting to the Impacts of Climate Change (NRC, 2010a) summarized potential regional climate-change impacts in a table that is excerpted below (Table 2-2). Such projections must be viewed with great caution, though. Among the uncertainties listed by the NRC report is “an inability to attribute explicitly many observed changes at local and regional scales to climate change.” In summary, vulnerability to health effects associated with climate change and indoor environmental quality will depend on the process under scrutiny and will be the result of an interaction of extrinsic and intrinsic factors. Most of the adaptation to climate change and resulting indoor en- vironmental quality will depend on changes implemented by the residents of homes. Some populations that lack the resources to change their homes’ ventilation systems or to repair water damage will suffer from increasing in- door temperatures and increasing humidity. Poorer communities, including people who live in developing countries, will be very susceptible to health effects of climate change and the indoor environment. Children, the elderly, and people who have chronic health conditions will be most susceptible to the effects of poor indoor environmental quality, and people who have

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TABLE 2-2 Summary of Selected Potential Regional Climate-Change–Related Impacts Climate Related Impacts Extreme Degraded Urban Rainfall Sea United States Air Heat Tropical with Level Census Region Quality Islands Wildfires Heat Waves Storms Flooding Rise ● ● ● ● ● New England ME VT NH MA RI CT ● ● ● ● ● ● Middle Atlantic NY PA NJ DE MD ● ● ● ● East North Central WI MI IL IN OH ● ● ● West North Central ND MN SD IA NE KS MO ● ● ● ● ● ● ● South Atlantic WV VA NC SC GA FL DC ● ● ● ● ● East South Central KY TN MS AL ● ● ● ● ● ● ● West South Central TX OK AR LA ● ● ● ● ● Mountain MT ID WY NV UT CO AZ NM ● ● ● ● ● ● ● Pacific AK CA WA OR HI (excerpted from NRC, 2010a; adapted from CCSP, 2008) 47

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48 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH pre-existing allergic conditions or respiratory diseases may find that their conditions are worsened. CONCLUSIONS On the basis of its review of the papers, reports, and other informa- tion presented in this chapter, the committee has reached the following conclusions related to the potential effects of climate change on the indoor environment and health, to time spent in indoor environments, and to vul- nerability. Later chapters revisit some of these issues in greater detail and offer additional observations. • T he frequency and intensity of some extreme weather events, such as heavy precipitation and heat waves, are increasing. Models suggest that there will be important regional differences in these events: some areas of the country will become drier and others and wetter. • T here is a lack of understanding of the linkages between climate change, indoor environmental quality, and health. • B ecause people spend the vast majority of their time in indoor environments, they will encounter many of the effects of climate change indoors. • V ulnerable populations will be disproportionately affected by cli- mate change and its adverse effects on indoor environmental qual- ity. Vulnerable populations include those who have less economic ability to adapt to or mitigate the effects of changes in their indoor environment and those whose age or health status renders them more susceptible to environmental stresses or insults. REFERENCES ASHRAE (American Society of Heating, Refrigeration, and Air-Conditioning Engineers). 2010. Ventilation for acceptable indoor air quality (Standard 62.1). Atlanta, GA: ASHRAE. Baker M, Keall M, Au E, Howden-Chapman P. 2007. Home is where the heart is—most of the time. Journal of the New Zealand Medical Association 120(1264):U2769. Balbus JM, Malina C. 2009. Identifying vulnerable subpopulations for climate change health effects in the United States. Journal of Occupational and Environmental Medicine 51(1): 33-37. Bernstein J, Alexis N, Bacchus H, Bernstein I, Fritz P, Horner E, Li N, Mason S, Nel A, Oullette J, Reijula K, Reponen T, Seltzer J, Smith A, Tarlo SM. 2008. The health effects of non-industrial indoor air pollution. Journal of Allergy and Clinical Immunology 121(3):585-591. Berry M. 1991. Indoor air quality: Assessing health impacts and risks. Toxicology and Indus- trial Health 7(5-6):179-186.

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