Elliott T. Gall

Measuring the Penetration of Ambient Ozone into Residential Buildings

Much of human exposure to ambient ozone and ozone reaction byproducts occurs inside buildings. However, there are currently no experimental data on the ability of ozone to penetrate through building envelopes and into residences. This paper presents a method to determine the penetration factor for ozone in buildings, and applies it in an unoccupied test house and seven single-family residences. The mean (±SD) ozone penetration factor was measured as 0.79 ± 0.13 in the eight homes using this method, ranging from 0.62 ± 0.09 to 1.02 ± 0.15. An analysis of tests across the homes revealed that ozone penetration was significantly higher in homes with more painted wood envelope materials, homes with larger air leakage exponents from fan pressurization tests, and older homes. The test method utilizes a large calibrated fan to elevate air exchange rates and steady-state indoor ozone concentrations to levels that can be accurately measured, so there is a potential for overpredicting ozone penetration factors. However, evidence suggests that this bias is likely small in most of the homes, and, even if a bias exists, the measured ozone penetration factors were lower than the usual assumption of unity in seven of the eight tested homes.

Indoor Air Pollution in Developing Countries: Research and Implementation Needs for Improvements in Global Public Health

Exposure to indoor air pollution (IAP) from the burning of solid fuels for cooking, heating, and lighting accounts for a significant portion of the global burden of death and disease, and disproportionately affects women and children in developing regions. Clean cookstove campaigns recently received more attention and investment, but their successes might hinge on greater integration of the public health community with a variety of other disciplines. To help guide public health research in alleviating this important global environmental health burden, we synthesized previous research on IAP in developing countries, summarized successes and challenges of previous cookstove implementation programs, and provided key research and implementation needs from structured discussions at a recent symposium.

Impact of physical properties on ozone removal by several porous materials.

Models of reactive uptake of ozone in indoor environments generally describe materials through aerial (horizontal) projections of surface area, a potentially limiting assumption for porous materials. We investigated the effect of changing porosity/pore size, material thickness, and chamber fluid mechanic conditions on the reactive uptake of ozone to five materials: two cellulose filter papers, two cementitious materials, and an activated carbon cloth. Results include (1) material porosity and pore size distributions, (2) effective diffusion coefficients for ozone in materials, and (3) material-ozone deposition velocities and reaction probabilities. At small length scales (0.02-0.16 cm) increasing thickness caused increases in estimated reaction probabilities from 1 × 10(-6) to 5 × 10(-6) for one type of filter paper and from 1 × 10(-6) to 1 × 10(-5) for a second type of filter paper, an effect not observed for materials tested at larger thicknesses. For high porosity materials, increasing chamber transport-limited deposition velocities resulted in increases in reaction probabilities by factors of 1.4-2.0. The impact of physical properties and transport effects on values of the Thiele modulus, ranging across all materials from 0.03 to 13, is discussed in terms of the challenges in estimating reaction probabilities to porous materials in scenarios relevant to indoor environments.

Modeling Ozone Removal to Indoor Materials, Including the Effects of Porosity, Pore Diameter, and Thickness

We develop an ozone transport and reaction model to determine reaction probabilities and assess the importance of physical properties such as porosity, pore diameter, and material thickness on reactive uptake of ozone to five materials. The one-dimensional model accounts for molecular diffusion from bulk air to the air-material interface, reaction at the interface, and diffusive transport and reaction through material pore volumes. Material-ozone reaction probabilities that account for internal transport and internal pore area, γ(ipa), are determined by a minimization of residuals between predicted and experimentally derived ozone concentrations. Values of γ(ipa) are generally less than effective reaction probabilities (γ(eff)) determined previously, likely because of the inclusion of diffusion into substrates and reaction with internal surface area (rather than the use of the horizontally projected external material areas). Estimates of γ(ipa) average 1 × 10(-7), 2 × 10(-7), 4 × 10(-5), 2 × 10(-5), and 4 × 10(-7) for two types of cellulose paper, pervious pavement, Portland cement concrete, and an activated carbon cloth, respectively. The transport and reaction model developed here accounts for observed differences in ozone removal to varying thicknesses of the cellulose paper, and estimates a near constant γ(ipa) as material thickness increases from 0.02 to 0.16 cm.

Progress and priorities in reducing indoor air pollution in developing countries.

A call to action for governments, institutions, corporations, and individuals worldwide to reduce the deadly effects of indoor air pollution (IAP) in developing countries was published in this journal 6 years ago (Indoor Air 16, 2–3, 2006), and the issue is no less urgent today. Nearly half the world s population still depends on solid fuels to meet their basic household energy needs. Exposure to pollutants from inefficient burning of solid fuel indoors for cooking, heating, and lighting accounts for a significant proportion of the global burden of disease. The World Health Organization estimates that nearly 2 million people die prematurely each year from exposure to IAP. Women and young children disproportionately shoulder the burden of adverse health effects. Unless swift and effective action is taken, the health risks associated with IAP are projected to rise as the number of people using these fuels increases. Has progress been made in the 6 years since the call to action was published in this journal? Promisingly, the answer is yes! Many regional, national, and international organizations and governments have initiated intervention efforts focused on improving cookstove design and performance. For example, in 2010 the United Nations Foundation launched the Global Alliance for Clean Cookstoves, a public– private initiative with the goal of getting 100 million homes to adopt clean cookstoves and fuels by 2020. However, it is important to acknowledge that improved cookstove dissemination programs have historically achieved mixed results, in part because there are both technical and social complexities associated with efforts aimed at successful adoption of clean cookstoves in developing countries. There remains a significant need for interdisciplinary research on intervention studies to address cookstoves as agents of public health risk and global climate change. To bring greater attention to this topic in the indoor air research community and to encourage a new generation of young researchers to enter this field, we, students at the University of Texas at Austin, initiated, managed, and ran a symposium on IAP in developing countries at the Indoor Air 2011 conference in Austin, TX, USA, on June 6–7, 2011. The symposium was supported by the US National Science Foundation s IGERT program, which allowed us to fund the attendance of nearly 30 students from a variety of disciplines. We sought to organize the symposium so that it would break new ground with several specific goals: (i) to forge connections between new and established researchers to accelerate new researchers entry into the field; (ii) to clarify the role of researchers within new cookstove dissemination programs and frameworks; and (iii) to redefine opportunities for future interdisciplinary research to help academic, nonprofit, and governmental agencies work together. Ultimately, the symposium provided substantial opportunities for exchange between new and established researchers, which is important for growth in any field. A student discussion panel focused on the experiences of working on IAP research in developing countries and highlighted the diversity of students engaged on this topic. It also revealed insights regarding best practices for introducing young researchers to the field and provided opportunities for engaging and assembling future research teams. A series of group and panel discussions provided an opportunity for networking with established professionals, who could provide young researchers with guidance and mentorship and also critically discuss the role of researchers in this field. Presentations from representatives from the Global Alliance for Clean Cookstoves and the US Environmental Protection Agency identified key issues for successful cookstove dissemination programs and enumerated roles for future researchers from the perspective of public agencies. Technical presentations (many of which were given by graduate and undergraduate students) provided a promising view of some exciting current developments in cookstove and IAP research in developing countries. Invited presentations provided a forum to discuss future directions for research and implementation. Discussions at the symposium identified many unique challenges that this field faces. For example, balancing the goal of obtaining new research data regarding specific stoves and interventions against the demonstrated need for early intervention must be considered and constantly reevaluated. The absence of field-ready, standardized stove test methods to complement wide-scale dissemination of cookstove infrastructure makes evaluation and comparison of Indoor Air 2012; 22: 1–2 wileyonlinelibrary.com/journal/ina Printed in Singapore. All rights reserved 2012 John Wiley & Sons A/S

Home energy-efficiency retrofits.

In the February 2011 issue of EHP, Manuel (2011) took an important look at some potential adverse health implications of home energy retrofits. Here, we further discuss the complexity of possible indoor environmental concerns and encourage incorporation of comprehensive homeowner education campaigns in weatherization programs. The reduction of air infiltration by air sealing is a common energy retrofit measure (McCold et al. 2008). Several field studies of weatherized homes have reported average reductions in air leakage of 13–40% (Berry and Brown 1994; Judkoff et al. 1988), although the impact of weatherization on actual air exchange rates and indoor pollutant concentrations is poorly understood. Moreover, studies have seldom evaluated the effects of weatherization on low-income groups or vulnerable populations (e.g., asthmatic or elderly), although occupants in low-income residences are at higher risk for many indoor environmental hazards (Evans and Kantrowitz 2002), and some population subgroups may also be disproportionately affected by indoor air pollution (Hun et al. 2009). Although some research exists on the impact of weatherization on indoor concentrations of combustion products, radon, and moisture, other indoor pollutants deserve attention. For example, Logue et al. (2011) identified nine priority indoor air pollutant hazards in U.S. residences, which, among others, have been associated with a wide range of both chronic and acute health effects (e.g., benzene, 1,4-dichlorobenzene, formaldehyde, naphthalene, particulate matter < 2.5 µm in aerodynamic diameter). Moreover, reducing air exchange rates in residences will likely increase indoor concentrations of reactive pollutants and the probability of chemical reactions occurring between them indoors (Weschler and Shields 2000), generating by-products associated with respiratory symptoms and asthma, such as low-molecular-weight aldehydes, dicarbonyls, and secondary organic aerosols (Jarvis et al. 2005). On the other hand, reductions in air infiltration should decrease penetration of outdoor pollutants, which is of particular importance in traditionally leakier low-income households (Chan et al. 2005) in neighborhoods with high outdoor air pollution. Thus, we urge the environmental health community to investigate the net effects of weatherization on a wide variety of indoor and outdoor pollutants and health outcomes. Implementation of home energy retrofits also creates an opportunity to incorporate innovative, engaging homeowner education strategies to reduce both energy consumption and indoor environmental risks. Occupant behavior has a major influence on both energy consumption (Allcott and Mullainathan 2010) and indoor exposures to pollutants (Meng et al. 2005). Furthermore, many indoor air quality risks can be mitigated with relatively simple home behavior practices, such as using exhaust fans, avoiding toxic cleaning chemicals, and using appropriate air cleaners (Brugge et al. 2003). However, we have learned from research on household energy consumption that educational materials alone usually fail to alter behaviors (Charles 2009). Greater energy savings from home retrofits could be achieved by complementing homeowner education campaigns with regular feedback on energy use and economically motivational programs (Peschiera et al. 2010). Additionally, home walkthroughs with trained building specialists can identify energy-inefficient behaviors and appliances in conjunction with potential indoor environmental hazards. These and other behavior-change strategies to promote green and healthy housing should be made available to weatherization programs across the country, and their effectiveness should be assessed. Because home weatherization is currently a priority of the federal government, this is a crucial time to address these fundamental research questions and implement the findings nationwide.

Priorities in indoor environmental science and health, as students see them

In a recent Indoor Air editorial (Volume 19, Issue 4, 2009), editor Jan Sundell wrote Indoor Air as a journal, as well as indoor air as a science, will die unless we start to co-operate, as Indoor Air and the society behind it, ISIAQ, are all aboutmultidisciplinary science! Howdire! Whether we consider deleterious effects in complex modern buildings or in rudimentary indoor systems in the developing world, indoor environments are fraught with human health hazards. Our highest goal, then, should not be to recruit lifelong indoor environmental scientists and engineers, but rather to clearly define human health challenges that take root in indoor environments and engage the expertise of teams and individuals from relevant disciplines to address them. Thus, while agreeing with Sundell s quote, we propose an alternate diction: Indoor environmental science and health research will flourish and progress when members from multiple disciplines collaborate and work toward common goals. Multiple disciplines cannot force common goals, yet solutions to problems in our field naturally encourage collaboration. The research questions in our field benefit from the inclusion of specialists from many disciplines, even if they do not focus entirely on indoor environments. Perhaps our field would further prosper by outcome-driven projects relying on many different outside specialists who would come to know the nature of our work in bits and pieces, rather than by convincing a few small groups of researchers to devote their careers to indoor environmental studies. In July 2009, with these collaborative goals in mind, we, the student members of a National Science Foundation (NSF) Integrative Graduate Education and Research Traineeship (IGERT) program in Indoor Environmental Science and Engineering at the University of Texas at Austin gathered to discuss research priorities in our field and to highlight some impending grand challenges we face as emerging indoor environmental scientists, but also as members of a larger, environmentally concerned scientific community. We produced the following list of priorities fromanovel, and previously unpublished, perspective: that of students.

Editorial: Priorities in indoor environmental science and health, as students see them: Editorial

In a recent Indoor Air editorial (Volume 19, Issue 4, 2009), editor Jan Sundell wrote Indoor Air as a journal, as well as indoor air as a science, will die unless we start to co-operate, as Indoor Air and the society behind it, ISIAQ, are all aboutmultidisciplinary science! Howdire! Whether we consider deleterious effects in complex modern buildings or in rudimentary indoor systems in the developing world, indoor environments are fraught with human health hazards. Our highest goal, then, should not be to recruit lifelong indoor environmental scientists and engineers, but rather to clearly define human health challenges that take root in indoor environments and engage the expertise of teams and individuals from relevant disciplines to address them. Thus, while agreeing with Sundell s quote, we propose an alternate diction: Indoor environmental science and health research will flourish and progress when members from multiple disciplines collaborate and work toward common goals. Multiple disciplines cannot force common goals, yet solutions to problems in our field naturally encourage collaboration. The research questions in our field benefit from the inclusion of specialists from many disciplines, even if they do not focus entirely on indoor environments. Perhaps our field would further prosper by outcome-driven projects relying on many different outside specialists who would come to know the nature of our work in bits and pieces, rather than by convincing a few small groups of researchers to devote their careers to indoor environmental studies. In July 2009, with these collaborative goals in mind, we, the student members of a National Science Foundation (NSF) Integrative Graduate Education and Research Traineeship (IGERT) program in Indoor Environmental Science and Engineering at the University of Texas at Austin gathered to discuss research priorities in our field and to highlight some impending grand challenges we face as emerging indoor environmental scientists, but also as members of a larger, environmentally concerned scientific community. We produced the following list of priorities fromanovel, and previously unpublished, perspective: that of students.

Editorial: Priorities in indoor environmental science and health, as students see them

In a recent Indoor Air editorial (Volume 19, Issue 4, 2009), editor Jan Sundell wrote Indoor Air as a journal, as well as indoor air as a science, will die unless we start to co-operate, as Indoor Air and the society behind it, ISIAQ, are all aboutmultidisciplinary science! Howdire! Whether we consider deleterious effects in complex modern buildings or in rudimentary indoor systems in the developing world, indoor environments are fraught with human health hazards. Our highest goal, then, should not be to recruit lifelong indoor environmental scientists and engineers, but rather to clearly define human health challenges that take root in indoor environments and engage the expertise of teams and individuals from relevant disciplines to address them. Thus, while agreeing with Sundell s quote, we propose an alternate diction: Indoor environmental science and health research will flourish and progress when members from multiple disciplines collaborate and work toward common goals. Multiple disciplines cannot force common goals, yet solutions to problems in our field naturally encourage collaboration. The research questions in our field benefit from the inclusion of specialists from many disciplines, even if they do not focus entirely on indoor environments. Perhaps our field would further prosper by outcome-driven projects relying on many different outside specialists who would come to know the nature of our work in bits and pieces, rather than by convincing a few small groups of researchers to devote their careers to indoor environmental studies. In July 2009, with these collaborative goals in mind, we, the student members of a National Science Foundation (NSF) Integrative Graduate Education and Research Traineeship (IGERT) program in Indoor Environmental Science and Engineering at the University of Texas at Austin gathered to discuss research priorities in our field and to highlight some impending grand challenges we face as emerging indoor environmental scientists, but also as members of a larger, environmentally concerned scientific community. We produced the following list of priorities fromanovel, and previously unpublished, perspective: that of students.