Browsing by Subject "Indoor air quality"
Now showing 1 - 15 of 15
Results Per Page
Sort Options
Item Advancements in concrete material sustainability : supplementary cementitious material development and pollutant interaction(2013-05) Taylor Lange, Sarah Clare; Juenger, Maria C. G.; Siegel, Jeffrey A.Calcined clay and fly ash supplementary cementitious materials (SCMs) used in cement based materials were examined for their chemical and mechanical performance, as well as their pollutant interaction. This dissertation addresses three primary research questions, namely: (i) can zincite additions facilitate the use of calcined clay as SCMs by compensating for reductions in early-age mechanical performance or by compensating for their reduced pozzolanic reactivity, (ii) can cement renders, containing metakaolin calcined clays, be engineered for passive carbon dioxide and ozone removal, and (iii) how do the specific activity and emanation fractions of concrete constituents, including fly ash and metakaolin, as well as assembled concretes impact concrete radon emanation and indoor radon concentrations? The first question relates directly to the development of new, sustainable material options, which can replace a portion of cement in a concrete mixture. Results from the experiments with zincite showed that the treatment method removed the dilution effect that occurs when using less reactive materials to substitute a portion of portland cement, but did not considerably influence mechanical properties. Therefore, zincite additions are not a good means of enhancing the utilization of non-kaolinite clays in concrete. As an integrated system, the latter two questions of this dissertation investigate the interaction between airborne pollutants and the cement based materials containing SCMs. The use of SCMs in render and concrete systems resulted in different pollutant uptake and exhalation behavior, relative to non-SCM control systems. For pollutant uptake, render systems containing metakaolin increased the carbon dioxide ingress while decreasing the ozone uptake. For radon exhalation rates, modeling results demonstrated that concretes without fly ash have a higher probability of containing less total radium and lower radon exhalation rates, when compared to samples with fly ash, assuming an emanation fraction of 5%, as suggested in the literature. Experimental results demonstrated that metakaolin, fly ash and control concretes had emanation fractions of 7%, 9% and 13%, respectively, confirming that (i) an assumed fraction of 5% would underpredict indoor radon concentrations and potential health consequences, and (ii) SCMs can reduce the total concrete emanation fraction. This dissertation demonstrates how the use of sustainable material selections, such as calcined clays and fly ashes, not only influences the microstructure and mechanical performance of the cement based materials, but also alters the interaction of the material with its surrounding environment.Item Assessing and controlling concentrations of volatile organic compounds in the retail environment(2014-05) Nirlo, Éléna Laure; Corsi, Richard L.; Siegel, Jeffrey A.Retail buildings have potential for both short-term (customer) and long-term (occupational) exposure to indoor pollutants. A multitude of sources of volatile organic compounds (VOCs) are common to the retail environment. Volatile organic compounds can be odorous, irritating or carcinogenic. Through a field investigation and modeling study, this dissertation investigates exposure to, and control of, VOCs in retail buildings. Fourteen U.S. retail stores were tested one to four times each over a period of a year, for a total of twenty-four test visits. Over a hundred parameters were investigated to characterize each of the buildings, including ventilation system parameters, and airborne pollutants both indoors and outdoors. Concentrations of VOCs were simultaneously measured using five different methods: Summa canisters, sorbent tubes, 2,4-dinitrophenylhydrazine (DNPH) tubes, a photoionization detector (PID), and a colorimetric real-time formaldehyde monitor (FMM). The resulting dataset was analyzed to evaluate underlying trends in the concentrations and speciation of VOCs, identify influencing factors, and determine contaminants of concern. A parametric framework based on a time-averaged mass balance was then developed to compare strategies to reduce formaldehyde concentrations in retail stores. Mitigation of exposure to formaldehyde through air cleaning (filtration), emission control (humidity control), and targeted dilution (local ventilation) were assessed. Results of the field study suggested that formaldehyde was the most important contaminant of concern in the retail stores investigated, as all 14 stores exceeded the most conservative health guideline for formaldehyde (OEHHA TWA REL = 7.3 ppb) during at least one sampling event. Formaldehyde monitors were strongly correlated with DNPH tube results. The FMM showed promising characteristics, supporting further consideration as real-time indicators to control ventilation and/or environmental parameters. The vast majority of the remaining VOCs were present at low concentrations, but episodic activities such as cooking and cleaning led to relatively high indoor concentrations for ethanol, acetaldehyde, and terpenoids. Results of the modeling effort demonstrated that local ventilation caused the most uniform improvements to indoor formaldehyde concentrations across building characteristics, but humidity control appeared to have a very limited impact. Filtration used under specific conditions could lead to larger decreases in formaldehyde concentrations than all other strategies investigated, and was the least energy-intensive.Item Assessing sheep’s wool as a filtration material for the removal of formaldehyde in the indoor environment(2014-05) Wang, Jennifer, active 21st century; Corsi, Richard L.Formaldehyde is one of the most prevalent and toxic chemicals found indoors, where we spend ~90% of our lives. Chronic exposure to formaldehyde indoors, therefore, is of particular concern, especially for sensitive populations like children and infants. Unfortunately, no effective filtration control strategy exists for its removal. While research has shown that proteins in sheep's wool bind permanently to formaldehyde, the extent of wool's formaldehyde removal efficiency and effective removal capacity when applied in active filtration settings is unknown. In this research, wool capacity experiments were designed using a plug flow reactor and air cleaner unit to explore the capacity of wool to remove formaldehyde given different active filtration designs. Using the measured wool capacity, filter life and annual costs were modeled in a typical 50 m₃ room for a variety of theoretical filter operation lengths, air exchange rates, and source concentrations. For each case, annual filtration costs were compared to the monetary benefits derived from wool resale and from the reduction in cancer rates for different population types using the DALYs human exposure metric. Wool filtration was observed to drop formaldehyde concentrations between 60-80%, although the effective wool removal capacity was highly dependent on the fluid mechanics of the filtration unit. The air cleaner setup yielded approximately six times greater capacity than the small-scale PFR designed to mimic active filtration (670 [mu]g versus 110 [mu]g HCHO removed per g of wool, respectively). The outcomes of these experiments suggest that kinematic variations resulting from different wool packing densities, air flow rates, and degree of mixing in the units influence the filtration efficiency and effective capacity of wool. The results of the cost--benefit analysis show that for the higher wool capacity conditions, cost-effectiveness is achieved by the majority of room cases when sensitive populations like children and infants are present. However, for the average population scenarios, filtration was rarely worthwhile, showing that adults benefit less from reductions in chronic formaldehyde exposure. These results suggest that implementation of active filtration would be the most beneficial and cost-effective in settings like schools, nurseries, and hospitals that have a high percentage of sensitive populations.Item Characterizing the impacts of air-conditioning systems, filters, and building envelopes on exposures to indoor pollutants and energy consumption in residential and light-commercial buildings(2012-05) Stephens, Brent Robert; Siegel, Jeffrey A.Residential and light-commercial buildings comprise a significant portion of buildings in the United States. They account for a large fraction of the total amount of energy used in the U.S., and they also represent environments where people spend the majority of their time. Thus, the design, construction, and operation of these buildings and their systems greatly affect energy consumption and exposures to airborne pollutants of both indoor and outdoor origin. However, there remains a need to improve knowledge of some key source and removal mechanisms of indoor and outdoor pollutants in residential and light-commercial buildings, as well as their connections to energy use and peak electricity demand. Several standardized field test methods exist for characterizing energy use and indoor air quality in actual buildings, although few explicitly address residential and light-commercial buildings and they are generally limited in scope. Therefore, the work in this dissertation focuses on improving methods to characterize three particular building components for their impacts on exposures to indoor pollutants and their implications for energy consumption: (1) central forced-air heating and cooling (HAC) systems, (2) HAC filters, and (3) building envelopes. Specifically, the research in this dissertation is grouped to fulfill two primary objectives of developing and applying novel methods to: (1) characterize and evaluate central air-conditioning systems and their filters as pollutant removal devices in residential and light-commercial buildings, and to explore their implications for energy consumption, and (2) characterize and evaluate the ability of two particular outdoor pollutants of concern (ozone and particulate matter) to infiltrate indoors through leaks in building envelopes. The research in this dissertation is divided into four primary investigations that fulfill these two objectives. The first investigation (Investigation 1a) addresses Objective 1 by first providing a detailed characterization of a variety of operational characteristics measured in a sample of 17 existing central HAC systems in occupied residential and light-commercial buildings in Austin, Texas, and exploring their implications for exposure to indoor pollutants, energy use, and peak electricity demand. Among the findings in this study, central air-conditioning systems in occupied residential and light-commercial buildings did not operate most of the time, even in the hot and humid climate of Austin, Texas (i.e., ~25% of the time on average in the summer). However, average recirculation rates still make central air-conditioning systems competitive as particle removal mechanisms, given sufficient filtration efficiency. Additionally, this investigation used a larger, much broader, dataset of energy audits performed on nearly 5000 single-family homes in Austin to explore common inefficiencies in the building stock. Residential and light-commercial air-conditioning systems are often inefficient; in fact, residential central air-conditioning systems in particular likely account for nearly 20% of peak electric demand in the City of Austin. As much as 8% of peak demand could be saved by upgrading all single-family homes in Austin to higher-efficiency equipment. The second investigation (Investigation 1b) also addresses Objective 1 by developing and applying a novel test method for measuring the in-situ particle removal efficiency of HAC systems and filters in residential and light-commercial buildings. Results from the novel test method as performed with three test filters and 0.3–10 μm particles in an unoccupied test house agreed reasonably well with results from other field and laboratory test methods. Low-efficiency filters did not increase particle removal much more than simply running the HAC system without a filter, and higher-efficiency filters provided greater than ~50% removal efficiency for most particles greater than 1–2 μm in diameter. The benefit of this test method is that it can be used to measure how filters perform in actual environments, how filter removal efficiency changes with actual dust loading, and how much common HAC design and installation issues, such as low airflow rates, duct leakage, fouled coils, and filter bypass airflow, impact particle removal in real environments. The third investigation (Investigation 2a) addresses Objective 2 by developing and applying a novel test methodology for measuring the penetration of outdoor ozone, a reactive gas, through leaks in exterior building envelopes using a sample of 8 single-family residences in Austin, Texas. These measurements represent the first ever measurements of ozone penetration factors through building envelopes of which I am aware, and penetration factors were lower than the usual assumption of unity (i.e., P = 1) in seven of the eight test homes (ranging from 0.62±0.09 to 1.02±0.15), meaning that some building envelopes provide occupants with more protection from indoor exposures to ozone and ozone reaction byproducts than others. Additionally, ozone penetration factors were correlated with some building characteristics, including the amount of painted wood siding on the exterior envelope and the year of construction, suggesting that simple building details may be used to predict ozone infiltration into homes. Finally, the fourth investigation (Investigation 2b) also addresses Objective 2 by refining and applying a test methodology for measuring the penetration of ambient particulate matter through leaks in building envelopes, and using a sample of 19 single-family residences in Austin, Texas to explore correlations between experimentally-determined particle penetration factors and standardized fan pressurization air leakage tests. Penetration factors of particles 20–1000 nm in diameter ranged from 0.17±0.03 to 0.72±0.08 across 19 homes that relied solely on infiltration for ventilation air. Particle penetration factors were also significantly correlated with results from standardized fan pressurization (i.e., blower door) air leakage tests and the year of construction, suggesting that occupants of older and leakier homes are exposed to more particulate matter of outdoor origin than those in newer tighter homes. Additionally, blower door tests may actually offer some predictive ability of particle penetration factors in single-family homes, which could allow for vast improvements in making easier population exposure estimates. Overall, the work in this dissertation provides new methods and data for assessing the impacts of central air-conditioning systems, filters, and building envelopes on human exposure to indoor pollutants and energy use in residential and light-commercial buildings. Results from these four primary investigations will allow building scientists, modelers, system designers, policymakers, and health scientists to make better informed decisions and assumptions about source and removal mechanisms of indoor pollutants and their impacts on building energy consumption and peak electricity demand.Item Clay-based materials for passive control of ozone and reaction byproducts in buildings(2016-05) Darling, Erin Kennedy; Corsi, Richard L.; Brown Wilson, Barbara; Juenger, Maria; Novoselac, Atila; Xu, YingTropospheric ozone that infiltrates buildings reacts readily with many indoor materials and compounds that are commonly detected in indoor air. These reactions lead to lower indoor ozone concentrations. However, the products of ozone reactions may be irritating or harmful to building occupants. While active technologies exist (i.e., activated carbon filtration in HVAC systems) to suppress indoor ozone concentrations, they can be costly and/or infeasible for dwellings that do not have these systems. Passive methods of ozone removal are an interest of building environment researchers. This dissertation involves (1) a review of the state of the knowledge on building materials and coatings that are intended to passively remove indoor ozone, especially clay-based materials; (2) a compilation of current data on ozone removal and reaction byproduct formation for these materials; (3) a model for ozone removal effectiveness for a selected clay-based material that is implemented in a hypothetical home; (4) a survey of the effects of a clay-based coating with and without ozone and a reactant source on human perceptions of air quality; (5) an investigation of the long-term potential for passive control of indoor ozone by two different clay-based surface coatings that were exposed to real indoor environments; and (6) development of a location-specific model to estimate the monetary benefits versus costs of indoor ozone control using passive removal materials. The above tasks were completed through ongoing reviews of the literature, experimental studies conducted in small and large environmental chambers, and in the field. Results of these studies suggest that clay or materials made from clay are a viable material for passive reduction of indoor pollution, due in part to clay’s ability to catalyze ozone. Human sensory perceptions of indoor air quality were shown to significantly improve when a clay-based plaster was present in an ozonated environment. Based on modeling efforts, effective passive removal of indoor ozone is possible for realistic indoor scenarios when clay-based materials are implemented. There is a growing number of papers that are published on the subject of clay materials and indoor environmental quality, but few that investigate the longer term impacts and performance of clay materials, especially ones that have been exposed to real indoor environments.Item Essays on environmental and natural resource economics(2010-08) Stafford, Teresa Michelle; Williams, Roberton C., 1972-; Abrevaya, Jason; Corsi, Richard; Fullerton, Don; Hamermesh, DanielIn the first essay, I assess the effect of indoor air quality (IAQ) in school buildings on student test performance and attendance rates. Results indicate that performance on standardized tests significantly improves while attendance rates are unresponsive to improvements in IAQ. The improvement in math scores ranges from 0.102 - 0.189 standard deviations per $500,000 spent on IAQ-related renovations and is 35% - 50% greater than the improvement in reading scores. For the same budget, results suggest that the improvement in math scores following IAQ-related renovations is several times larger than the improvement associated with class size reductions. In the second essay, I examine the responsiveness of the daily labor supply of fishermen to transitory variations in the daily wage using data from the Florida spiny lobster fishery. The applicability of this research is both narrow and general. Understanding this relationship is key to determining the effectiveness of landing fees as a means to regulate fisheries. Tracing out the labor supply curve is also fundamental to labor economics and policy. I find that the wage elasticity of labor supply (participation) is positive and statistically different from zero, with a point estimate of 0.967. This suggests an upward slopping labor supply curve and refutes the notion of reference dependent preferences. In the third essay, I examine the bias associated with ignoring the multi-species aspect of labor supply decisions in spatially explicit bioeconomic fishery models. Using a complete 15-year panel of all fishing trips made by fishermen possessing a Florida spiny lobster license, including non-lobster trips, I show that the simplifying assumption of a dichotomous choice structure at the first node (i.e. participate in the target fishery or not) is not innocuous and that predicted participation rates can change substantially with the addition of another species as an outside alternative in the first decision node.Item Growth and mycotoxin production by Chaetomium globosum(Texas Tech University, 2007-05) Fogle, Matthew R.; Straus, David C.; Hamood, Abdul N.; Fralick, Joe A.; Dickerson, Richard L.; Bright, RobertSick building syndrome (SBS) is a term commonly used to describe a set of non-specific symptoms resulting from poor indoor air quality (IAQ). These symptoms include: irritation of the eyes, nose and throat, dry skin, fatigue, headache, nausea, dizziness, increased number of respiratory tract infections, hoarseness, and wheezing. Over the last several years, mounting evidence has shown that fungal contamination within buildings is associated with SBS. The focus of this project is on a filamentous fungus called Chaetomium globosum which produces chaetoglobosins A (Ch-A) and C (Ch-C) when cultured on building material. Both metabolites belong to a group of toxins called the cytochalasins which exert their effects on mammalian cells by binding to actin. The production of Ch-A and Ch-C may contribute to the adverse health effects described by building occupants exposed to C. globosum. Therefore, examination of the growth of C. globosum and its mycotoxin production is important with regard to determining if there is a link between adverse health effects and exposure to Ch-A and Ch-C. This study had four major objectives: (1) to determine the frequency at which Chaetomium species are isolated in water-damaged buildings, (2) to examine the production of Ch-A and Ch-C in isolates of C. globosum obtained from different buildings, (3) to examine heat stability and water solubility of Ch-A and Ch-C, and (4) to examine the effects of ambient pH on growth and mycotoxin production by C. globosum. We found that Chaetomium species were commonly isolated from water-damaged buildings. Out of 30 C. globosum isolates, 16 produced detectable amounts of Ch-A and every isolate produced Ch-C. C. globosum grows best and produces the highest amount of Ch-C at a neutral pH. Ch-A and Ch-A were relatively stable when exposed to 50oC up to 3 days; however, decreased amounts were detected at longer exposure times. Exposure to 75oC and higher temperatures resulted in rapid breakdown of Ch-A and Ch-C. Both compounds were poorly soluble in water.Item Indoor air quality in retail stores(2011-05) Rhodes, Joshua Daniel; Siegel, Jeffrey A.; Xu, YingRetail stores are understudied given the energy, occupant health, and potential sales impacts associated with poor indoor air quality (IAQ). There is also evidence of elevated pollutants in retail environments. This thesis is an exploration of the indoor air quality of retail stores. The first section of this thesis is a literature review on field investigations of the indoor air quality in retail buildings. Sixteen investigations report different measurements in 17 specific types of retail environments. Measurements vary depending on the specific investigation, but include VOCs, SVOCs, particles, microbiological species, and radon. When reported, indoor to outdoor ratios of almost all pollutants are greater than unity, suggesting the importance of indoor sources in retail environments. The second section of this thesis is an analysis of the whole store net emission factor for different retail environments. From the types of pollutants found in the retail store investigations, VOCs were the only pollutant group studied frequently enough to merit this analysis. The final section is an analysis of the potential for pollutant remediation strategies. Two methods, increasing air change rate and air cleaning, are considered with an analysis of the energy penalties associated with each.Item Indoor biological exposures : what can HVAC filter dust tell us?(2016-05) Jennings, Wiley Charles; Kinney, Kerry A.; Maestre Wic, Juan PedroBecause people in the US spend an estimated 80-90% of their time indoors, much of it at home, understanding the potential health impacts of biological exposures that occur in the home is crucial. Recently, rapid advances in high-throughput DNA sequencing technology have spurred increased study of the relationships between the human and built environment microbiomes. HVAC filters hold promise as long-term, spatially integrated, high volume samplers to characterize the airborne home microbiome. In order to optimize HVAC sampling protocols and improve comparability between studies employing HVAC filters for bacterial community analysis, three HVAC filter dust sampling methods were compared. These three methods, vacuuming the filter surface, swabbing the filter surface, and eluting filter dust in a buffer, were selected as representative of previously published methods. Our findings suggest that vacuum and swab samples produced more repeatable and representative bacterial communities than did elution. Furthermore, given the reduced labor and cost of vacuum and swab methods, and the additional advantage that these two methods may also be applied to sampling dust from other home surfaces, vacuum and swab sampling of HVAC filter dust are found to be superior to elution.Item Monolayer and multilayer particle resuspension from indoor surfaces : literature review and experimental methodology(2010-12) Boor, Brandon Emil; Novoselac, Atila; Siegel, Jeffrey A.Resuspension is an important source of particles in the indoor environment. A variable that may have a significant impact on the fraction of particles removed from indoor surfaces is the type of particle deposit. Particles may be deposited in either a monolayer, where there is minimal particle-to-particle contact, or a multilayer, where there is substantial particle-to-particle contact and interaction. This paper provides a review of theoretical and experimental studies on particle resuspension from monolayer and multilayer particle deposits. In addition, an experimental methodology was developed to determine resuspension from the two types of deposits on indoor surfaces. Seeded samples were exposed to controlled flow conditions in a micro-scale wind tunnel and were analyzed with fluorescence stereomicroscopy. Resuspension was found to occur at significantly lower velocities for multilayer deposits compared to monolayer deposits.Item The nexus of energy and health : a systems analysis of costs and benefits of ozone control by activated carbon filtration in buildings(2015-08) Aldred, Josh Ryan; Corsi, Richard L.; Novoselac, Atila; Kinney, Kerry; Liljestrand, Howard; Siegel, JeffreyAmericans spend nearly 90% of their lifetimes indoors, where they receive 50-70% of their exposure to ozone. The US EPA has designated ozone as a hazardous air pollutant and ozone exposure has been linked to respiratory mortality, hospital admissions, restricted activity days, and school loss days. In addition, the most susceptible populations to ozone exposure are children and the elderly, especially if they suffer from an existing respiratory health condition. One possible solution to reduce indoor ozone exposure is to use activated carbon filtration in a building's heating, ventilation, and air conditioning (HVAC) system. In many cases, using commercially available activated carbon filters will have minimal additional capital and energy costs in comparison to standard particle filters. A complex systems model for evaluating the potential costs and benefits of ozone control by activated carbon filtration in buildings was developed as part of this dissertation. The modeling effort included the prediction of indoor ozone concentrations and exposure with and without activated carbon filtration. As example applications, the model was used to predict benefit-to-cost ratios for commercial office buildings, long-term healthcare facilities, K-12 schools, and single-family homes in 12 American cities in five different climate zones. Health outcomes due to reduced indoor ozone exposure were determined using the USEPA methodology for outdoor ozone exposure, which includes city-specific age demographics and disease prevalence. Health benefits were evaluated using disability-adjusted life-years, which were then converted to a monetary value to compare with activated carbon filtration costs. Modeling results indicate that activated carbon filtration during the summer ozone season should be beneficial and economically feasible in commercial office buildings, long-term healthcare facilities, and K-12 schools. The benefits of activated carbon filtration in single-family homes are predicted to be marginal, except for sensitive populations or in cities with high seasonal ozone and high air conditioning usage. Field experiments of activated carbon filters in an operational university laboratory resulted in an average ozone single-pass removal efficiency of 70%. An additional benefit-cost analysis of activated carbon filtration in the laboratory showed that ozone-related health costs were reduced by 62% and fan energy costs were reduced by 21% compared to a baseline condition. Finally, the field study demonstrated that activated carbon filtration for ozone removal could be economically beneficial in buildings with very high ventilation due to reductions in health, energy, and filter replacement and installation costs.Item Ozone transport to and removal in porous materials with applications for low-energy indoor air purification(2013-05) Gall, Elliott Tyler; Corsi, Richard L.; Siegel, Jeffrey A.In the U.S. and other developed countries, humans spend the vast majority of their time within the built environment. As a result, a substantial portion of our collective exposure to airborne pollutants, even those of outdoor origin, occurs in indoor environments. In addition, building construction materials and operational practices are changing as we endeavor to reduce the energy burden of the built environment. These changes result in barriers and opportunities in mitigating exposure to indoor pollutants and the accompanying implications for human health. This dissertation advances knowledge regarding low-energy control of indoor ozone. Ozone is often considered a pollutant of outdoor concern. However, ozone in indoor environments presents important challenges regarding exposure, intake, and chemistry in the built environment. The investigations in this dissertation extend the state understanding of indoor transport and transformation of ozone, and the potential for using material-surface interactions in buildings to suppress concentrations of indoor ozone. The first objective relates to the determination of magnitudes of ozone removal and product emissions at room or building scales. This objective provides new data on reactive uptake and product generation in large-scale environments, develops Monte Carlo models describing indoor ozone removal by materials in homes, and compares active and passive methods of indoor ozone removal. The second objective addresses the need to develop improved air cleaning materials through experiments and modeling that address material-ozone reactions in porous materials. This objective advances the state of modeling heterogeneous reactive uptake of ozone by characterizing material physical properties and transport phenomena, determining their impact on ozone removal, and using these data to develop a more mechanistic model of material-ozone reactions. Ultimately, these investigations advance the engineering concepts that support the development of passive indoor pollutant controls, an important tool for reducing concentrations of indoor pollutants while supporting low-energy building initiatives. The combination of experimental characterization of ozone deposition velocities and product emission rates, whole-building Monte Carlo modeling, and mechanistic material/pollutant models provide important new data and approaches that expand the state of knowledge of the fate and transport of reactive pollutants in indoor environments.Item Particulate reactive oxygen species in indoor and outdoor environments : prevalence and health effects(2015-05) Khurshid, Shahana Sarfraz; Kinney, Kerry A.; Siegel, Jeffrey A; Corsi, Richard; Novoselac, Atila; Wells, J. RaymondReactive Oxygen Species (ROS) are an important class of air pollutants generated from photochemical and ozone-initiated reactions in indoor and outdoor environments. Despite the fact that Americans spend nearly 90% of their time inside buildings and extended exposures to ROS can occur in indoor environments, ROS has received very little attention as an indoor pollutant. This is one of the first research studies to measure the concentration of particulate ROS (on PM [subscript 2.5] and TSP) in indoor environments. A significant fraction of indoor particulate ROS was found to exist on PM [subscript 2.5] (58±10%) which is important from a health perspective since PM [subscript 2.5] can carry ROS deep into the lungs. The indoor concentrations of ROS on PM [subscript 2.5] sampled in residential and commercial buildings were not significantly different from the outdoor concentrations. This result is intriguing because it implies that generation of ROS inside buildings and/or transport of outdoor ROS and precursors of ROS into buildings are important processes and can be as significant as ROS generation in outdoor environments. Controlled studies show that when outdoor ozone concentrations are relatively low, indoor concentrations of ROS are dominated by indoor sources of ROS rather than outdoor sources of ROS. However, when outdoor ozone concentrations are relatively high, indoor and outdoor sources of ROS contribute almost equally to the indoor concentration of ROS. This study is also one of the first to assess seasonal variations in outdoor particulate ROS concentrations. Ambient sampling conducted over an 11-month period indicates that outdoor particulate ROS concentrations are influenced by the ozone concentration, solar radiation intensity and temperature. In order to understand the potential health effects of exposure to ROS, an in vitro exposure system of lung epithelial cells and differentiated lung tissue was also utilized. Results from these experiments indicate that exposure to products of limonene ozonolysis (which include ROS) can lead to a greater inflammatory response than exposure to either ozone or limonene. This highlights the need to include biologically relevant pollutants, such as ROS, in indoor air quality studies. Further work is warranted to better understand the parameters that drive indoor particulate ROS concentrations.Item Pollutant control strategies for acceptable indoor air quality and energy efficiency in retail buildings(2013-12) Zaatari, Marwa; Novoselac, Atila; Siegel, Jeffrey A.Indoor air is associated with substantial health risks and is estimated to be responsible for the loss of over 4.7 million healthy life years (years lost due to morbidity and mortality) annually in the U.S. The highest indoor air-related health benefits can be expected from policies and strategies that efficiently target pollutants having the greatest contribution to the burden of disease. This burden is caused by indoor sources as well as by outdoor pollutants transported to the indoors. The diversity of pollutants, pollutant sources, and the resulting health effects challenge the comparison of the impacts of different control strategies on energy consumption and indoor air quality. To address this challenge, this work presents a quantitative framework for reaching the optimal energy cost for the maximum achieved exposure benefits, specifically for retail buildings and their understudied energy, economic, and health risk influence. The main objectives of this dissertation are to 1) determine pollutants of concern in retail buildings that contribute the greatest to the burden of disease, and 2) determine energy-efficient, exposure-based control strategies for different retail types and locations. The research in this dissertation is divided into four specific aims that fulfill these two objectives. The first specific aim (Specific aim 1.a) addresses Objective 1 by applying available disease impact models on pollutant concentrations taken from 15 literature studies (150 stores, a total of 34 pollutants). Of those pollutants, there was little data reported on particulate matter (PM) concentrations and none on emission rates for PM, limiting our understanding of exposure to this pollutant. The second specific aim (Specific aim 1.b) also addresses Objective 1 by characterizing particulate matter (PM) concentrations, emission rates, and fate of ambient and indoor-generated particles in retail buildings. The tasks of this specific aim consisted of particulate matter and ventilation measurements in 14 retail buildings. Among the findings of Objective 1, PM2.5 and acrolein are the main contaminants of concern for which control methods should be prioritized, contributing to 160 disability-adjusted life years (DALYs; years lost due to premature mortality and disability) per 100,000 persons annually. Employees in grocery stores mainly drove this burden. An efficient indoor exposure reduction strategy should take into account all mechanisms that influence pollutant concentrations: indoor and outdoor sources (highlighting the importance of retail type and location), infiltration, ventilation, and filtration. The remaining specific aims address Objective 2 by investigating the energy and air quality impact of two commonly used exposure control scenarios, ventilation (Specific aim 2.a) and filtration (Specific aim 2.b). The tasks of Specific aim 2.a consisted of modeling the impact of multiple ventilation strategies on contaminants of concern for six major U.S. cities and two retail types. The tasks for Specific aim 2.b consisted of conducting field measurements on 15 rooftop units to determine the fan energy impacts of filter pressure drop. These results are used in combination with a large dataset of 75 filters commonly installed in commercial buildings to estimate the energy consequences of filtration. Results for Objective 2 are presented from the quantitative comparison of the impact on energy usage and DALYs lost of three main approaches: (1) adjusting ventilation only; (2) adjusting filtration only; and (3) adjusting ventilation and filtration together. All approaches were able to provide substantial reductions in the health risks (19-26% decrease in DALYs lost); the magnitude of the reductions depended on the ventilation/filtration scenario, the retail type, and the city. The magnitude of energy cost to achieve the maximum health benefits depended on the city and the retail type (for example for a 10,000 m2 grocery store, the energy cost ranged from $1,100 for the annual cost of filtration energy in Los Angeles to $24,000 for the annual cost of ventilation in Austin). The uncertainties of the estimates driving these findings are discussed throughout the results section. The finding that emerges from this analysis is the pollutant exposure control ventilation (PECV) strategy. This strategy is superior to the ventilation rate procedure (VRP; ASHRAE Standard 62.1-2010) and the indoor air quality procedure (IAQP; ASHRAE Standard 62.1-2010) as it decides on a range of ventilation rates by weighing the exposures of contaminants of concern found in retail buildings. Then, among the range of ventilation rates identified, the PECV recommends the optimal ventilation rate that leads to energy usage savings in the climate considered. Overall, the work presented here prioritizes specific contaminants of concern in retail buildings and proposes an exposure-based, energy-efficient control strategy for different retail types and locations. Policy makers, engineers, and building owners can use these results to decide amongst appropriate control strategies that will lead to minimum energy consumption and, at the same time, will not compromise occupant health. This work can be repeated for different types of buildings, notably for residences, schools, and offices where abundant information is available on both pollutant concentrations and ventilation rates, but where information is lacking on how to optimize the control strategies for better indoor air quality.Item Studies on particle resuspension, infant exposure, and the sleep microenvironment(2015-08) Boor, Brandon Emil; Xu, Ying (Assistant professor); Novoselac, Atila; Corsi, Richard L; Hildebrandt Ruiz, Lea; Järnström, Helena; Howard Reed, CynthiaUnderstanding the transport of particulate and gaseous indoor air pollutants from source to exposure is paramount to improve our understanding of the complexities of the built environments in which we spend the majority of our time. This dissertation offers new insights on particle resuspension from indoor surfaces, infant exposure to organic contaminants released from crib mattresses, and the dynamics of pollutant transport and human exposure while sleeping. Particle resuspension is the physical process by which settled particles detach from a surface and become airborne through application of various aerodynamic and mechanical removal forces. Resuspension is an important indoor source of coarse mode particles (> 1 µm in diameter) and can be a source mechanism for biological matter and organic contaminants that accumulate in house dust. Settled dust deposits on indoor surfaces can vary considerably in their structure and mass loading, yet little is known as to how these parameters affect resuspension. Through wind tunnel experiments, this research demonstrates that the deposit structure (monolayer or multilayer) can have a significant impact on the number of particles that aerodynamically resuspend. Furthermore, this dissertation presents the first full-scale experimental chamber study to show that human body movements in bed can resuspend settled mattress dust particles. An indoor aerosol model was utilized to provide a mechanistic understanding of the impact of movement intensity, surface vibrations, bedroom ventilation rate, and dust loading on the resuspension flux and intake fraction of resuspended particles. Infants spend most of their time sleeping and are likely to be exposed to elevated concentrations of chemicals released from their crib mattresses. Through a combination of chamber experiments and solvent extractions, this research shows that infant crib mattresses can emit a variety of volatile organic compounds (VOCs) and contain numerous chemical additives, including phthalate and alternative plasticizers, flame retardants, and unreacted isocyanates. Additionally, this study discovered that infants are exposed to approximately twice the concentrations of VOCs in their breathing zones as compared to the bulk bedroom air, due to their close proximity to the source.