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1 Introduction This chapter provides basic information about the report’s motivation and the conduct of the study, beginning with an overview of why the ef- fects of climate change on the indoor environment and health constitute an important issue. It then presents the statement of task for the Institute of Medicine (IOM) committee responsible for this report, which is followed by the committee’s approach to its task. The text then addresses some of the methodologic considerations that informed the committee’s evaluation of the literature and concludes with a description of the report’s organization. WHY THE EFFECT OF CLIMATE CHANGE ON THE INDOOR ENVIRONMENT AND HEALTH CONSTITUTES AN IMPORTANT ISSUE The indoor environment affects comfort, health, and productivity. People in developed countries spend most of their time indoors, so most of the adverse exposures that they encounter regularly take place indoors. Many exposures that are potentially hazardous to health are exposures to substances emitted indoors from indoor sources. Such emissions can oc- cur from building materials; from products used or stored indoors; from processes that occur in indoor environments; from the microorganisms, insects, other animals, and plants that live indoors; and from the behavior of building occupants. Because of the contributions from indoor sources, indoor levels of many pollutants are higher than those found outdoors. In addition to pollutants attributable to indoor sources, ventilation may draw pollutants into buildings from outdoor air. Buildings offer protection 17

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18 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH against some pollutants that are of predominantly outdoor origin; but that protection is generally incomplete. And some outdoor pollutants that enter a building interact with its components or contents and thereby alter the composition of indoor air in ways that can affect the health and welfare of occupants. Climate change has the potential to affect the indoor environment. Ambient conditions in the outdoor environment serve as boundary condi- tions to the ambient conditions of the indoor environment. Outdoor air temperature, humidity, air quality, precipitation, and land surface wetness can all influence the indoor environment, depending on such factors as the integrity of a building’s envelope; the state of its heating, ventilation, and air-conditioning systems; the inhabitants of the outdoor ecosystem; and the characteristics of the buildings around it. If climatic conditions in a particular area change—for example, if the climate becomes warmer or if there are more severe or more frequent episodes of high heat or intense precipitation—buildings (and other infrastructure) that were designed to operate under the “old” conditions may not function well under the “new.” Furthermore, in responding to climate changes, people and societies will seek to mitigate undesirable changes and adapt to changes that cannot be mitigated. Some of their responses will play out in how built spaces are designed, constructed, used, maintained, and in some cases retrofitted, and the actions taken may well have consequences for indoor environmental quality and public health. There is a body of literature on how the indoor environment influences occupant health and how the external environment influences the internal built environment under past and present climate conditions. And research is emerging on the possible effects of climate change—such as extreme tem- peratures and thermal stress, vectorborne infectious diseases, and outdoor air quality—on human health. However, the body of research specific to the effects of climate change on human health in the indoor environment is very small. Such studies are complicated by the fact that the effects of climate change on, say, indoor air quality depend on the geographic region and are a function of the age and condition of the regionally dependent built environment. Against that backdrop, the US Environmental Protection Agency (EPA) approached IOM with a request to summarize and benchmark the state of the science concerning the health effects of climate change–induced al- terations in the indoor environment, raise awareness of crucial issues, and suggest a way forward. The Committee on the Effect of Climate Change on Indoor Air Quality and Public Health was formed to respond to that request.

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19 INTRODUCTION STATEMENT OF TASK EPA charged the committee to develop a report summarizing the cur- rent state of scientific understanding of the effects of climate change on indoor air and public health. It provided three examples of key questions to address: • W hat are the likely impacts of climate change in the United States on human exposure to chemical and biological contaminants inside buildings, and what are the likely public health consequences? • W hat are the likely impacts of climate change on moisture and dampness conditions in buildings, and what are the likely public health consequences? • W hat are priority issues for action? EPA indicated that it intended the report to serve as the foundation for the development of US government funding priorities and for use in communi- cations to and guidance for the public. THE COMMITTEE’S APPROACH TO ITS TASK To answer the questions posed by EPA, the committee undertook a wide-ranging evaluation of relevant research on climate change, buildings, indoor environmental quality, and occupant health. Although the commit- tee did not review all such literature—an undertaking beyond the scope of this report—it did attempt to cover the work that it believed to have been influential in shaping scientific understanding by at the time it completed its task in early 2011. The committee consulted several sources of information. On health outcomes, the primary source was epidemiologic studies. Most of those studies examined general population exposures to problematic agents in homes, reflecting the focus of researchers working in the field. The commit- tee also examined the smaller literature addressing commercial buildings, apartments, schools, and other buildings. Clinical and toxicologic research were considered as appropriate. The literature of engineering, architecture, and the physical sciences informed the committee’s discussions of building characteristics, exposure assessment and characterization, pollutant transport, and related topics; and public-health and behavioral-sciences research was consulted for the discussion of public-health implications. Those disciplines have different practices regarding the publication of research results. For example, rela- tively few papers in the peer-reviewed literature address building construc- tion or maintenance issues. The committee endeavored in all cases to

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20 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH identify, review, and consider fairly the literature most relevant to the topics that it was charged to address. Papers and reports reviewed in this volume were identified through extensive searches of relevant databases. Most were bibliographic and provided citations of peer-reviewed scientific literature. Committee staff ex- amined the reference lists of major papers, books, and reports for relevant citations, and committee members independently compiled lists of potential citations on the basis of their expertise. The input received in both written and oral form from participants at three public meetings held in February– July 2010 served as a valuable source of additional information. Appendix A lists the participating researchers and their topics. The committee also relied on the research and conclusions of prior National Academies committees that addressed indoor environment and health issues. The 2004 IOM report Damp Indoor Spaces and Health and the 2006 National Research Council report Green Schools: Attributes for Health and Learning (NRC, 2006) were particularly influential. Research published after their completion dates is used to supplement this material. The committee did not attempt to review and evaluate the literature regarding potential effects of climate change on the outdoor environ- ment or health independently. Several National Academies reports have addressed those topics in detail, including Global Climate Change and Extreme Weather Events: Understanding the Contributions to Infectious Disease Emergence (NRC, 2008) and four published in 2010: Advanc- ing the Science of Climate Change (NRC, 2010b), Limiting the Mag- nitude of Climate Change (NRC, 2010d), Adapting to the Impacts of Climate Change (NRC, 2010a), and Informing an Effective Response to Climate Change (NRC, 2010c). Salient findings, conclusions, and recommendations from those and other National Academies reports are referenced throughout the present report. EPA also commissioned several white papers addressing various issues related to climate change, the indoor environment, and health to serve as information resources for the committee. The papers, which are listed in Appendix C, were helpful sources of references and perspectives for the committee to consider. In some cases, they delve into topics at a greater level of detail than is present in this report. The papers are the work product of their authors and do not necessarily represent the committee’s point of view. METHODOLOGIC APPROACH This section presents the general considerations regarding climate change, the indoor environment, and public health that informed the com- mittee’s approach to evaluating the scientific literature. It discusses, in general terms, the major issues involved in determining environmental con-

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21 INTRODUCTION ditions in buildings and how building characteristics, occupant behavior, and the outdoor environment may affect them. The committee’s statement of task directed it to focus on indoor air quality (IAQ), a major component of indoor environmental quality (IEQ),1 and the text reflects that guidance. General Considerations As detailed later in this report, little in the literature considers together the key elements in the committee’s charge: the effects of climate change on IEQ that would influence public health. However, substantial research has been published on many key questions. For example, there is a strong emerging literature on the effects of climate change on outdoor air pol- lution. A voluminous literature characterizes health risks associated with pollutants2 in outdoor air. Considerable published research documents our understanding of indoor–outdoor relationships with respect to important air pollutants. Research has explored the extent to which health risks as- sociated with outdoor pollution are a consequence of indoor exposures. There is a large body of work reporting on how indoor pollution sources influence IAQ and human health, including several National Academies reports (IOM, 1993, 2000, 2004; NRC, 1981). A number of papers are available on the determinants of exposure to indoor dampness and on the association of dampness or dampness-related agents with health outcomes. And the health effects associated with prolonged exposure to temperature extremes is relatively well studied. However, little published research links climate change to changes in levels of indoor air pollutants or to other changes in indoor environmental conditions that might influence public health. Among the available studies, Ayres et al. (2009)—summarizing how climate change is expected to affect respiratory health—called for more research on “the role of housing and indoor climate control systems in respiratory diseases.” Bell et al. (2009) used an epidemiologic approach to discern that communities with higher air-conditioner prevalence exhibited “lower health effects estimates” associ- ated with outdoor particulate-matter levels. The use of air conditioning for residential climate control would be expected to provide better protection against outdoor particles than would opening windows. Peden and Reed (2010) review the many ways in which indoor pollution and outdoor pollu- tion influence the prevalence and severity of allergic diseases. They discuss 1 Indoor environmental quality is defined by a building’s indoor air quality and the comfort of its occupants, which is influenced by factors such as the building’s ventilation, temperature, humidity, sound, and light levels. 2 A pollutant is anything that, at some concentration or level, is harmful to humans or the environment. It includes biologic, chemical, and particulate agents.

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22 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH the role that climate change will have in altering the spatial and temporal patterns of outdoor aeroallergens. In perhaps the most directly relevant study, Wilkinson et al. (2009) evaluated cobenefits of mitigating climate change and improving public health that would result from improving the residential building stock in the United Kingdom and from an improved stoves program in India. Even though the climate-change–IEQ–public-health nexus has not yet been well studied, the elements are sufficiently well understood to permit the committee to conduct a scientific examination of issues, come to find- ings, draw conclusions, and offer recommendations. The approach taken is to identify exposures and exposure circumstances believed to affect the health, safety, or productivity of building occupants; to describe the fac- tors that influence exposure or source strength; and to explore how climate change might influence these factors. Because the analysis relies on infer- ence, the committee was constrained to focus on portions of the system that are well understood mechanistically. In extrapolating from available evidence to explore an unknown future, the committee is on more solid ground when inferences are based on a cause–effect understanding of the system rather than when it has to rely on studies that base associations on statistical methods without providing clear evidence on processes. Because of those limitations, the report stresses how climate-change phenomena might induce changes in adverse exposures. In a few cases, the mechanistic level of understanding is sufficient to relate potential changes in future ex- posures to health consequences. Framing the Issues Fundamentally, exposures occur when people and pollutants intersect in space and time. The magnitude of an exposure depends on its level while a subject is present. Three classes of factors govern conditions in occupied indoor environments. The first pertains to the adverse exposures themselves and includes such factors as the outdoor level and, in some cases, the physical properties of the agent. The second category pertains to buildings and includes the air-exchange rate, the characteristics of temperature and humidity controls, the presence and effectiveness of deliberate air-cleaning processes, and the types and conditions of materials that make up the build- ing surfaces and furnishings; this category also includes factors that affect emissions from materials associated with the building and its (nonhuman) contents. The third category of factors pertains to occupants and includes the timing of their presence indoors, occupant density, and activities that may influence both sources and exposure. Each category is complex: ad- verse exposures, buildings, and people are both numerous and diverse with

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23 INTRODUCTION regard to many attributes. The factors in each category can influence IEQ and its public-health consequences. It is convenient to decompose the analysis of indoor exposures into two components: outdoor and indoor sources. For many pollutants, these two components do not interact directly, and the total indoor burden can be represented as their arithmetic sum.3 The ventilation or air-exchange rate of a building or of a room in a building can substantially influence indoor air-pollutant concentrations and other environmental conditions. Ventilation is the means by which pollutants of outdoor origin are introduced into an indoor environment. Whether a pollutant is of outdoor or indoor origin, ventilation is commonly an important removal mechanism that limits its accumulation indoors. In fact, a main purpose for ventilating buildings is to remove indoor-generated pollutants, including those emitted by human occupants. In general, higher ventilation rates cause indoor environmental quality to become more like local outdoor environmental quality. Conversely, as ventilation rates are reduced, the indoor environment is progressively less influenced by pollut- ants of outdoor origin and outdoor environmental conditions and more strongly influenced by indoor sources and conditions. Climate change could influence IEQ in many ways. First, considering the existing building stock, a substantial influence can be expected from • C hanges in the levels of outdoor air pollutants or other outdoor conditions, which affect indoor human exposure from outdoor sources. • C hanges in how buildings are operated, for example, with respect to ventilation rate or air-conditioner use, which in turn alters in- door conditions. • A djustments in how occupants behave—for example, changing where they spend time or what they do indoors—in response to outdoor conditions and the resulting changes in the indoor envi- ronment or in exposure opportunities. Climate-change effects may occur over decades and one should expect concomitant changes in the building stock. These building-stock changes might substantially influence the nature of climate change and its effects on IEQ and health. There might also be changes in how occupants behave in buildings that evolve on decadal time scales and materially alter the level and nature of indoor exposures. 3 An example of this approach in the case of particulate matter—specifically, the mass concentration of particles finer than 10 µm in diameter, that is, PM10—is given by Ott et al. (2000).

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24 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH A change in building design, building operation, or habitual indoor human behavior that is influenced by climate change might be categorized as either an adaptation or a mitigation. An adaptation is a change made in response to climate change to provide protection against its effects. Increased use of air conditioning would be an adaptation in response to higher average ambient temperatures. Mitigation is a change made to re- duce or offset an effect. Because a large proportion of society’s use of fossil fuels is associated with buildings, buildings are and will probably continue to be settings where improved energy performance is sought. Some changes motivated by the goal of saving energy can have consequences for IEQ and public health. In addition to adaptation and mitigation that can be expected, one should be mindful of behavioral responses to climate catastrophes that may themselves have serious consequences for IEQ and public health. Ex- amples would be actions taken to protect people and property in response to floods, extreme heat events, or power outages. A specific concern that is discussed in more detail later in this report is the indoor use of back-up electricity generators after extreme weather events, which has been associ- ated with carbon monoxide (CO) poisonings (Hampson and Stock, 2006). The effects of climate change on IEQ will probably depend on build- ing type. The consequences of the effects will depend on how long people spend in different types of indoor environments and on differences in the populations that occupy various building types. As detailed in Chapter 2, people spend most of their time in their own residences. Children spend a high proportion of their time in school, and they are considered more vul- nerable than adults to adverse health effects of air pollution. Analogously, indoor environments occupied by the elderly or where health care is pro- vided would be of special concern because those who are in fragile health are more vulnerable to further stresses than those who are healthy. Differentiating among building types is important for reasons that extend beyond the populations that inhabit them. Different classes of build- ings may be designed, operated, and maintained differently in ways that affect their responsiveness to climate change. For example, office buildings in the United States are commonly ventilated mechanically whereas the existing stock of residential buildings is ventilated mainly by a combination of air leakage (infiltration) and natural ventilation through open windows or doors. Buildings also differ in types of pollutant-emitting sources of con- cern. For example, cooking is a dominant activity in restaurants, common in residences, and rare in offices. Candle use is largely confined to restau- rants and in residences. The intensity of use of cleaning products may be higher in health-care facilities than in other types of buildings. Finally, it is important to recognize that the responsibility for environmental conditions in buildings varies markedly among building classes and that this variability

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25 INTRODUCTION influences the appropriateness of policy options to address the public-health concerns discussed here. Another important characteristic of indoor environments is their broadly distributed nature. That results in far greater diversity in indoor environmental conditions than tends to occur outdoors. Consider, for ex- ample, that in the United States, more than half the population lives in the 52 most populous metropolitan statistical areas (MSAs), as defined by the Office of Management and Budget. Although there is some local and neigh- borhood variability in air-pollutant concentrations in those areas, there are also some common characteristics, and the air quality of each MSA can be reasonably characterized by using a relatively small number of monitoring stations. Furthermore, the actions of small numbers of individuals in an MSA have little influence on urban air quality. In contrast, the population of the United States resides in about 100 million residential units, and there are tens of millions of other occupied buildings in the US stock. What hap- pens in individual buildings strongly influences the quality of the indoor environment in those buildings but generally does not substantially affect IEQ in other buildings. In turn, the IEQ in a given building can affect the health of people oc- cupying that building but generally would not affect others. Diversity in building stock is especially important for understanding the public-health significance of how climate change might affect IEQ. Subpopulations that are potentially vulnerable to the adverse consequences of climate-change– induced effects on IEQ include not only those who are more susceptible to air-pollutant health effects or to temperature extremes because they are young, old, or infirm but those who lack the financial resources or the ap- propriate knowledge to act wisely in response to an emergency induced by a climate-change event. In light of that broad diversity, what factors affect indoor pollutant levels? According to the principle of material balance (that is, that mass is conserved), the level of a given pollutant in a particular building can be determined by accounting for the net effect of the source terms and the removal processes. Sources include outdoor air and direct indoor emis- sions. Similarly, indoor dampness and temperature levels are a function of indoor and outdoor levels. Ventilation is a removal process that must always be considered. For some pollutants and for some buildings, other removal processes can be important, such as deposition of particles onto indoor surfaces, irreversible reaction of a pollutant with an indoor surface, or active filtration. Buildings are ventilated so that the replacement time of indoor air with outdoor air occurs on a time scale that is typically a few hours but may range from about 5 min, in the case of a mechanically ventilated building using an economizer or a building with open doors and windows, to about

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26 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH 10 h, in the case of a closed building that is on the tight end of the normal range. Dynamic, time-dependent relationships governing the relationship between indoor and outdoor levels are important for time scales similar to or shorter than the ventilation time scale, but the time-dependent processes are not as important for evaluating longer-term average conditions. In many epidemiologic studies, consideration of the effects of outdoor on indoor conditions is based on one-time measurements or time-averaged condi- tions rather than short-term dynamics. However, short-term dynamics are important in the event of high exposure concentrations that lead to acute and severe health effects. Changes in IEQ can be expected if homes become more tightly sealed as a response to increasing temperatures and humidity outdoors or because of efforts to reduce building energy use. Tightly sealed buildings tend to have decreased ventilation rates and higher levels of indoor-emitted pollutants. In general, the key elements that help to ensure good IEQ are indoor source control; adequate ventilation; and proper management of indoor environmental conditions through temperature and humidity control and, where appropriate, the use of air filtration, air cleaning, or other mecha- nisms to achieve further improvements. The central principle is to remove pollutants where they are more highly concentrated, to supply clean air where people need it, and to maintain comfortable environmental condi- tions for building occupants. The use of exhaust fans in bathrooms and the use of range hoods above cooking appliances, for example, are practi- cal illustrations of efficient ventilation. Deliberate air cleaning for indoor environments is widely practiced only in the case of particle filtration in mechanically ventilated buildings, and there are opportunities to do more. Chapters 4–8 discuss how indoor environmental conditions might be influenced by climate change. They are not intended to constitute a com- prehensive review of the literature but rather to be broadly illustrative of important IEQ concerns that might be influenced by climate change. Most of what follows is concerned with conditions in buildings of the types commonly found in the United States, but the report also addresses an im- portant international public-health problem: exposure to smoke from the indoor combustion of solid biomass and coal, which occurs predominantly in developing countries. RECENT NATIONAL ACADEMY OF SCIENCES REPORTS ADDRESSING CLIMATE CHANGE In 2007, the Congress tasked the National Oceanic and Atmospheric Administration to contract with the National Academy of Sciences to

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27 INTRODUCTION investigate and study the serious and sweeping issues relating to global climate change and make recommendations regarding what steps must be taken and what strategies must be adopted in response to global climate change, including the science and technology challenges thereof. (Public Law 110-161, §114) The National Research Council initiated the America’s Climate Choices research effort in response. This program has produced several publications that offer a broader perspective on climate change issues than is provided in this report. Primary publications are summarized below.4 Limiting the Magnitude of Climate Change (NRC, 2010f) describes, analyzes, and assesses strategies for reducing the net future human influ- ence on climate, including both technology and policy options. The report focuses on actions to reduce domestic greenhouse gas emissions and other human drivers of climate change, such as changes in land use, but also considers the international dimensions of limiting climate change. Adapting to the Impacts of Climate Change (NRC, 2010a) evaluates strategies to adapt to climate change in different regions, sectors, systems, and populations. The report reviews options and barriers to reduce vulner- ability; increase adaptive capacity; improve resiliency; and promote success- ful adaptation. This report identifies lessons learned from past experiences, promising current approaches, and a framework for a national adaptation strategy. Advancing the Science of Climate Change (NRC, 2010b) provides an overview of past, present, and future climate change, including its causes and its impacts; and recommends steps to advance our current under- standing, including new observations, research programs, next-generation models, and the physical and human assets needed to support these and other activities. The report focuses on the scientific advances needed both to improve the understanding of the integrated human-climate system and to devise more effective responses to climate change. Informing an Effective Response to Climate Change (NRC, 2010e) describes and assesses different activities, products, strategies, and tools for informing decision-makers about climate change and helping them plan and execute effective, integrated responses. The report describes the different types of climate change-related decisions and actions being taken at various levels and in different sectors and regions; and develops a framework, tools, and practical advice for ensuring that the best available technical knowl- edge about climate change is used to inform these decisions and actions. America’s Climate Choices (NRC, 2011), the final report in the series, 4 The summaries below are adapted from descriptions contained in NRC, 2010a.

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28 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH recommends actions that should be taken at the national level to minimize the risks associated with climate change. It proposes an iterative risk man- agement approach that comprises “identifying risks and response options, advancing a portfolio of actions that emphasize risk reduction and are robust across a range of possible futures, and revising responses over time to take advantage of new knowledge.” The report also recommends a co- ordinated effort across the government to conduct research on adaptation and other climate change issues. Among these, Advancing the Science of Climate Change addresses the issues most closely related to this report. Although it does not men- tion the indoors specifically, it does devote chapters to both public health and cities and built environment, and briefly touches on energy efficiency improvements. The key research needs identified by the study include the following: • C haracterize the differential vulnerabilities of particular popula- tions to climate-related impacts, and the multiple stressors they already face or may encounter in the future. • I dentify effective, efficient, and fair adaptation measures to deal with health impacts of climate change. • D evelop integrated approaches to evaluate ancillary health benefits (and unintended consequences) of actions to limit or adapt to cli- mate change. • D evelop and test approaches for limiting and adapting to climate change in the urban context, including, for example, the efficacy of and social considerations involved in adoption and implementation of white and green roofs, landscape architecture, smart growth, and changing rural-urban socioeconomic and political linkages. • I mprove understanding of urban governance capacity, and develop effective decision support tools and approaches for decision mak- ing under uncertainty, especially when multiple governance units may be involved. • D evelop better understanding of informing, communicating with, and educating the public and health professionals as an adaptation strategy. In addition, two 2010 workshop reports from the National Research Council contain relevant information. Facilitating Climate Change Re- sponses (NRC, 2010d) illustrates some of the ways the behavioral and social sciences can contribute to climate research. It addresses both mitigation— which it defines as “behavioral elements of a strategy to reduce the net future human influence on climate”—and adaptation—“behavioral and

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29 INTRODUCTION social determinants of societal capacity to minimize the damage from climate changes that are not avoided”—strategies, and includes discussions of the ways to stimulate behavioral changes that achieve emissions reductions from household actions and induce household investments in energy efficiency. Describing Socioeconomic Futures for Climate Change Research and Assessment (NRC, 2010c) notes that the implications of climate change for the environment and society depend not only on the rate and magnitude of climate change, but also on changes in technology, economics, lifestyles, and policy that affect the capacity both for limiting and adapting to climate change. The report explores driving forces and key uncertainties that affect impacts, adaptation, vulnerability, and mitigation and considers research needs and the elements of a strategy for describing socioeconomic and en- vironmental futures for climate change research and assessment. ORGANIZATION OF THE REPORT The remainder of this report is divided into eight chapters and support- ing appendixes. Chapter 2 sets the scene for the later sections by providing background information on a set of topics relevant 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 condi- tions indoors, how the indoor environment affects health, and the amount of time that people spend indoors. The chapter also addresses populations that are particularly vulnerable to health problems associated with the indoor environment. It identifies the five major issues related to potential alterations in IEQ induced by climate change: air quality; dampness, mois- ture, and flooding; infectious agents and pests; thermal stress; and building ventilation, weatherization, and energy use. Several government and private-sector bodies are involved in various aspects of issues of climate change, the indoor environment, and health issues. Chapter 3 identifies them and summarizes their work. It also lists some major sources of data on the characteristics of buildings, the indoor environment, and health, and discusses how they might inform questions about the intersection between these three topics. Chapter 4 examines the first of the report’s major issues: indoor air quality. It focuses on the sources and health effects of chemical and par- ticulate pollutants that can be found suspended in air and in some cases deposited on or sorbed to indoor surfaces. The text addresses volatile and semivolatile molecular pollutants, both organic and inorganic, and abiotic particulate matter. There are also brief discussions of allergens associated with pollen, of respiratory health risks associated with algal blooms after floods, and of CO exposure associated with the use of home electricity

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30 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH generators typically used during power outages. The chapter concludes with a discussion of an important international public-health problem: exposure in developing countries to smoke from the indoor combustion of solid biomass and coal. IEQ problems associated with dampness, moisture, and flooding are addressed in Chapter 5. The problems include the effects of exposure to mold and hydrophilic bacteria and their components and exposure to deg- radation products of wet materials. The discussion in this chapter builds on a set of major literature reviews, including the IOM report Damp Indoor Spaces and Health (IOM, 2004), highlighting their findings and other re- search relevant to the consideration of the health effects of alterations in IEQ induced by climate change. Chapter 6 addresses IEQ concerns associated with infectious agents, insects and arthropods, and mammals that research suggests may be influ- enced by climate-change–induced alterations in the indoor environment. The chapter also touches on exposures to chemicals used to control pest infestations in buildings. “Thermal Stress,” Chapter 7, considers IEQ problems associated with the thermal environment of buildings, how climate change could induce alterations in the frequency or severity of problems, and some of the means available to mitigate adverse conditions. Thermal stress is a particular threat to certain populations whose health, economic situation, or social circumstances make them vulnerable to exposure to temperature extremes or the consequences of such exposure, and the text thus focuses on these groups. Because climate models suggest that trends toward longer and more extreme heat waves and shorter and milder cold spells will continue and intensify, much of the information presented in the chapter relates to issues involving prolonged exposure to high temperature. Chapter 8 concludes the discussion of major issues related to potential alterations in IEQ induced by climate change. It focuses on building energy use, emissions from building materials, weatherization and ventilation, and how these affect occupants. The chapter includes the topics of energy consumption in buildings, the means used to tighten buildings, programs to enhance the energy efficiency of buildings and reduce harmful emissions from building components, the training of personnel who implement weath- erization programs, and the effects of tightening on ventilation, IEQ, and occupant health and productivity. The final chapter of the report—Chapter 9—builds on the foundation of the foregoing to draw out the overarching themes of the report and present the committee’s key findings, guiding principles, and high-priority issues for action. Agendas of the public meetings held by the committee are provided in Appendix A. Appendix B contains summaries of the contents of a set of

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31 INTRODUCTION white papers on topics related to climate change, the indoor environment, and health that were commissioned by EPA to provide information for the committee’s consideration. Biographic information on the committee members and staff responsible for this study are provided in Appendix C. REFERENCES Ayres JG, Forsberg B, Annesi-Maesano I, Dey R, Ebi KL, Helms PJ, Medina-Ramón M, Windt M, Forastiere F. 2009. Climate change and respiratory disease: European Respiratory Society position statement. European Respiratory Journal 34:295-302. Bell ML, Ebisu K, Peng RD, Dominici F. 2009. Adverse health effects of particulate air pollu- tion: Modification by air conditioning. Epidemiology 20:682-686. Hampson NB, Stock AL. 2006. Storm-related carbon monoxide poisoning: Lessons learned from recent epidemics. Undersea & Hyperbaric Medicine 33(4):257-263. IOM (Institute of Medicine). 1993. Indoor allergens. Assessing and controlling adverse health effects. Washington, DC: National Academy Press. IOM. 2000. Clearing the air. Asthma and indoor air exposures. Washington, DC: National Academy Press. IOM. 2004. Damp indoor spaces and health. Washington, DC: The National Academies Press. NRC (National Research Council). 1981. Indoor pollutants. Washington, DC: National Academy Press. NRC. 2006. Green schools: Attributes for health and learning. Washington, DC: The National Academies Press. NRC. 2008. Global climate change and extreme weather events: Understanding the contri- butions to infectious disease emergence: Workshop summary. Washington, DC: The National Academies Press. NRC. 2010a. Adapting to the impacts of climate change. Washington, DC: The National Academies Press. NRC. 2010b. Advancing the science of climate change. Washington, DC: The National Academies Press. NRC. 2010c. Describing socioeconomic futures for climate change research and assessment: Report of a workshop. Washington, DC: The National Academies Press. NRC. 2010d. Facilitating climate change responses: A report of two workshops on insights from the social and behavioral sciences. Washington, DC: The National Academies Press. NRC. 2010e. Informing an effective response to climate change. Washington, DC: The Na- tional Academies Press. NRC. 2010f. Limiting the magnitude of climate change. Washington, DC: The National Academies Press. NRC. 2011. America’s climate choices. Washington, DC: The National Academies Press. Ott W, Wallace L, Mage D. 2000. Predicting particulate (PM10) personal exposure distribu- tions using a random component superposition statistical model. Journal of the Air & Waste Management Association 50(8):1390-1406. Peden D, Reed CE. 2010. Environmental and occupational allergies. Journal of Allergy and Clinical Immunology 125:S150-S160. Wilkinson P, Smith KR, Davies M, Adair H, Armstrong BG, Barrett M, Bruce N, Haines A, Hamilton I, Oreszczyn T, Ridley I, Tonne C, Chalabi Z. 2009. Public health benefits of strategies to reduce greenhouse-gas emissions: Household energy. Lancet 374:1917-1929.

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