Climate Change, the Indoor Environment, and Health (2011) / Chapter Skim
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4 Air Quality
4 Air Quality
Pages 79-132
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From page 79... ...
However, substantial research has been published on many important components. For example, there is a strong emerging literature on the effects of climate change on outdoor air pollutants (Jacob and Winner, 2009)
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From page 80... ...
Although most of what follows is related to conditions in buildings of the types commonly found in the United States, the chapter concludes with a discussion of an important international public-health problem: exposure to smoke from the indoor combustion of solid biomass and coal in developing countries. INDOOR SOURCES OF POLLUTANTS Indoor environments detain pollutants that are emitted indoors.
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From page 81... ...
Mott et al. analyzed CO-associated mortality statistics and concluded that, "if rates of unintentional COrelated deaths had remained at pre-1975 levels, an estimated additional 11,700 motor-vehicle-related CO poisoning deaths might have occurred by 1 Building tightening and reduced ventilation rates are further discussed in Chapter 8.
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From page 82... ...
If the generators are used indoors, or even outdoors but too close to an indoor environment, unhealthful CO exposures can result. Increases in emergency-room and other hospital visits caused by CO poisoning have been reported in association with power outages (Muscatiello et al., 2010)
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From page 83... ...
For example, the use of natural gas as a cooking fuel is associated with increased indoor exposures to nitrogen dioxide (NO2) , a byproduct of the combustion process (Marbury et al., 1988; Spengler et al., 1994)
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From page 84... ...
(2009) investigated the determinants of exposure for a cohort of Spanish women and found that personal NO2 levels were "strongly influenced by indoor NO2 concentrations." They also found that outdoor NO2 levels and the use of gas appliances were important determinants of indoor NO2 levels, whereas no significant association "was found between personal or indoor NO2 levels and exposure to environmental tobacco smoke (ETS)
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From page 85... ...
However, as practiced today, residential wood combustion is associated with degraded neighborhood air quality owing to emissions exhausted from chimneys and is associated with degraded IAQ in the households that burn the wood owing to leakage of combustion byproducts into the indoor environment (Gustafson et al., 2008; Traynor et al., 1987)
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From page 86... ...
. ETS is also an important cause of environmental exposure to some hazardous air pollutants, including acrylonitrile, 1,3-butadiene, acetaldehyde, acrolein, and formaldehyde (Nazaroff and Singer, 2004)
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From page 87... ...
. Mitigation measures to reduce energy use in buildings could lead to systematically lower ventilation rates and alteration of internal airflows that could cause higher concentrations and exposures to secondhand smoke.
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They concluded that "exposure to the smoke of mosquito coils similar to the tested ones can pose significant acute and chronic health risks." As in the case of other indoor combustion activities, climate change would affect IAQ and potentially public health if it were accompanied by a change in the source emission rate (for example, owing to a change in use) or were accompanied by a change in the other factors that influence exposures associated with a given magnitude of emissions.
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From page 89... ...
However, the effective radiation dose to lung tissue associated with a given level of indoor radon depends on the dynamic behavior of the short-lived decay products (Porstendörfer, 1994) , which can be influenced not only by the ventilation rate but by such factors as indoor particle levels, active air filtration, and the intensity of indoor air movement.
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From page 90... ...
Organic compounds that have extremely low volatility can also be present purely in the condensed phase and could still contribute to IAQ concerns as constituents of particulate matter. An important example of this category would be polycyclic aromatic hydrocarbons (PAHs)
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From page 91... ...
reviewed 21 studies from the "epidemiologic literature on associations between indoor residential chemical emissions, or emission-related materials or activities, and respiratory health or allergy in infants or children." He found that the most frequently identified risk factors included "formaldehyde or particleboard, phthalates or plastic materials, and recent painting." Emissions of VOCs indoors tend to be higher after new construction and renovation activities because of releases from finite-capacity reservoirs in wood-based products, paints, floor finishes, glues, and other construction and finishing materials (Dales et al., 2008; Herbarth and Matysik, 2010)
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From page 92... ...
In subsections that follow, indoor exposure conditions and associated health concerns are summarized for two important examples in the broader category of VOCs and SVOCs: formaldehyde and endocrine-disrupting chemicals. Overall, however, the state of knowledge about VOCs and SVOCs in indoor environments and their consequences for public health is far from complete.
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From page 93... ...
. Residential formaldehyde levels are influenced by ventilation rates.
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From page 94... ...
Higher indoor temperatures and relative humidities might be expected in some indoor environments as a consequence of climate change. In response to the first modern energy crisis in the 1970s, ureaformaldehyde foam insulation (UFFI)
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From page 95... ...
. Human exposure to indoor air and to dust enriched with endocrine-disrupting chemicals released from indoor sources has become an issue of increasing concern (Hwang et al., 2008; Rudel et al., 2003, 2010)
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Potential health risks posed by PCBs remain high in some indoor environments because of weak removal processes and long-term release from sources (Herrick et al., 2004; Rudel et al., 2008)
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From page 97... ...
In the United States, there are no health-based guidelines or standards for CO2 itself that would apply for the general public in all indoor environments. In Germany, a governmental work group recommended that "based on health and hygiene considerations: concentrations of indoor air carbon dioxide levels below 1000 ppm are regarded as harmless, those between 1000 and 2000 ppm as elevated and those above 2000 ppm as unacceptable" (Ad-hoc Work Group, 2008; translated in Heinzow and Sagunski, 2009)
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From page 98... ...
(1999) reviewed the literature on ventilation rates, CO2 concentrations, and sick-building syndrome symptoms.
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From page 99... ...
. Those two air pollutants, PM and O3, currently receive the most attention in outdoor air-pollution control policy, and urban environments are furthest from compliance with air-quality standards for them.
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Important secondary contributions to fine particles are associated with emissions of gaseous ammonia (NH3) , nitrogen oxides (mainly NO)
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From page 101... ...
Absent active filtration, higher ventilation rates tend to produce higher indoor concentrations of outdoor particles. The reason is that ventilation serves as the sole source introducing outdoor particles into indoor air but as only one of several removal mechanisms.
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Regulated Particulate Matter With respect to the first question, it is useful to consider the possibilities sorted into several categories of outdoor particles. Particles in outdoor air are subject to air-pollution control regulations.
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From page 103... ...
Because of the proximity of urban roadways to buildings, tailpipe emissions from vehicles have a higher effectiveness in causing indoor-air pollutant exposure per unit mass emitted than do central-station power plants, which emit their pollutants from tall stacks, often on the edge of or remote from populous regions. As with coal-fired electricity, an effective response to climate change in the transpor tation sector might yield cobenefits in reducing indoor exposure to PM.
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From page 104... ...
Because wood-smoke particles are primarily in the fine mode, ordinary indoor environments, especially residences, do not provide much protection from them. However, Barn et al.
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From page 105... ...
assessed mortal ity statistics in 15 California counties for 1999–2005 in relation to coarse-particle monitoring data and found "evidence of an associa tion between acute exposure to coarse particles and mortality" and that "lower socioeconomic status groups may be more susceptible to its effects." Indoor Proportion of Outdoor Particles The building stock in the future may substantially differ from current conditions. The body of evidence is weak for predicting how such changes may affect the infiltration and persistence of particulate matter from outdoor air.
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From page 106... ...
Ozone and Its Byproducts Ozone is a secondary pollutant that is formed in the atmosphere by photochemical reactions involving NOx and VOCs. Ozone concentrations in outdoor air have declined slowly in the United States, resisting relatively vigorous efforts to control precursor emissions.
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From page 107... ...
These considerations overlap but are not coincident. Overall, if ambient O3 concentrations increase while ventilation rates decrease, the net effect on indoor O3 concentrations is uncertain, because changes in these two factors have opposing influence on indoor ozone levels.
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The committee did not identify any literature specifically regarding climate change and indoor exposure to pollen. Algal Blooms After Floods Harmful algal blooms (HABs)
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The committee could not, however, identify any literature specifically addressing changes in risk associated with exposure to these agents in indoor environments.
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From page 110... ...
Future ambient SO2 levels might rise or fall depending on changes in the use of coal as an energy source and on emission controls. The indoor environment provides some protection against SO2 because, as an acid gas, it reacts on indoor surface materials (Biersteker et al., 1965; Grøntoft and Raychaudhuri, 2004; Walsh et al., 1977)
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From page 111... ...
On the other hand, levels of indoor HAPs that are attributable to their presence in outdoor air have not been well studied. For some important species, such as benzene and the chlorinated organics, it is reasonable to expect that indoor environments provide little or no protection from outdoor concentrations.
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From page 112... ...
Research also has demonstrated that indoor air pollution from solid biomass fuels may contribute to climate change as a result of emissions of black carbon, methane, CO, and nonmethane VOCs (which are O3 precursors)
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From page 113... ...
There has been experience with large national stove programs, such as the provision of 180 million improved stoves in China over 12 years starting in 1983. A modeling exercise indicated that a 150 million–stove program in India, to be implemented over 10 years, that would provide improved-efficiency cookstoves through various delivery mechanisms, including to poor women receiving antenatal care, could result in the prevention of around 2.2 million premature deaths from acute respiratory infections in children and from COPD and ischemic heart disease in adults (Wilkinson et al., 2009)
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From page 114... ...
More work is also needed on how changes in forest management, such as the trend toward greater use of forest plantations to supply roundwood, and the commercial exploitation of crops for biofuel, may affect the availability of biomass for use by poor households and thus indirectly affect the indoor environment. CONCLUSIONS On the basis of its review of papers, reports, and other information presented in this chapter, the committee has reached the following conclusions regarding the effects of climate change on IAQ and its consequent influence on public health.
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From page 115... ...
• I ndoor pollutant concentrations can be separated into contribu tions from indoor sources and from outdoor air. Combustion is a major source of both outdoor and indoor air pollution and is arguably the most important source of indoor air pollutants with respect to health risks.
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A lower building ventilation rate will tend to provide enhanced protection against some pollutants from outdoors, such as PM. But reduced ventilation rates tend to cause concentrations of pollutants that originate primarily from indoor sources to increase.
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Pollutant emissions from sources like these might be substantially worsened by climate change. If so, indoor environments will be used as imperfect shelters that could be improved with proper attention and a commitment of appropri ate resources.
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2006. Determining the infiltration of outdoor particles in the indoor environment using a dynamic model.
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2004. Sources and impacts of pesticides in indoor environment.
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From page 120... ...
Atmospheric Environment 42:642-654. Colt JS, Davis S, Severson RK, Lynch CF, Cozen W, Camann D, Engels EA, Blair A, Hartge P
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2010c. The Clean Air Act Amendments of 1990 list of hazardous air pollutants.
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1994. Environmental tobacco smoke and lung cancer in nonsmoking women -- A multicenter study.
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2011. Association between sub-standard classroom ventilation rates and students' academic achievement.
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From page 124... ...
Atmospheric Environment 33:4535-4564. Kattan M, Gergen PJ, Eggleston P, Visness CM, Mitchell HE.
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Atmospheric Environment 37:5633-5644.
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2001. Exposure assessment of air pollutants: A review on spatial heterogeneity and indoor/outdoor/personal exposure to suspended particulate matter, nitrogen dioxide and ozone.
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2004. Inhalation of hazardous air pollutants from environmental tobacco smoke in US residences.
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1986. Personal exposure to nitrogen dioxide: Relationship to indoor/outdoor air quality and activity patterns.
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2010. Formaldehyde in the indoor environment.
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From page 130... ...
Atmospheric Environment 37:5597-5609. Slama K, Chiang C-Y, Hinderaker SG, Bruce N, Vedal S, Enarson DA.
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2008. Semivolatile organic compounds in indoor environments.
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Atmospheric Environment 44:3609-3620. WHO (World Health Organization)
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