published_or_final_version / abstract / Mechanical Engineering / Master / Master of Philosophy

This dissertation consists of three chapters on questions in Environmental Economics, addressing policy and health issues in indoor and outdoor environments. In the first chapter, I explores price and quantity policy solutions to externalities that arise from private decisions made over time, focusing on resource extraction as a specific example. In the U.S., mining causes more pollution than any other single industry. I show how tax policy can optimally address a flow externality associated with resource extraction when the policymaker faces asymmetric information in the short run. Chapter 2 investigates whether ordinary exposure to a common indoor air pollutant—Nitrogen Dioxide (NO₂)—affects respiratory health. About 40 percent of occupied homes in the U.S. use gas stoves for cooking, which produce NO₂ as a byproduct of combustion (US Census, 2006), and peak concentrations in homes may reach above 900 ppb when a gas stove is used for cooking (Dennekamp et al., 2001). Permanent or fatal lung damage occurs at NO₂ concentrations greater than 1000 ppb (Samet and Utell, 1990). Previous studies find mixed evidence of negative effects from indoor NO₂ (Basu and Samet, 1999), but exposure may be endogenous in these analyses. I address this problem by developing a physical model of indoor NO₂ concentrations that depends on ventilation decisions and housing characteristics and estimate it using data from the third wave of the National Health and Nutrition Examination Survey. In every model I consider, I find no significant effects of gas stoves on respiratory outcomes. In the final chapter, I combine data on state and local tobacco control ordinances from Americans for Non-smokers Rights Tobacco US Tobacco Control Laws Database with a sample of 35 million births in the U.S. to examine the impact of smoking bans on birth weight and related outcomes. Using difference-in-difference techniques, I identify the effects of state bans net of local bans, as well as the effects of local bans net of state bans. The results suggest less restrictive bans do more to improve birth outcomes than “100% smokefree” bans do, particularly in urban settings. / text

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. / text

Formaldehyde is a ubiquitous and hazardous indoor air pollutant and reducing concentrations in indoor environments is a public health priority. The goals of this doctoral work were to advance analytical methods for continuous monitoring of formaldehyde at very low concentrations (sub-20 ppb[subscript v]) and to improve fundamental, mechanistic understanding of how structural and chemical properties of activated carbon influence removal of formaldehyde from indoor environments. To achieve these goals, emerging sensor-based technology was evaluated for its ability to detect and quantify ppb[subscript v]-level formaldehyde concentrations on a continuous basis at relative humidity levels characteristic of residential indoor environments. Also, a combination of spectroscopic and selective titration techniques was employed to characterize molecular-level structural and chemical properties of traditional and chemically treated granular activated carbon (GAC). In addition to selecting two different commercially available GACs for study, design and preparation of a laboratory-prepared, chemically treated GAC was pursued to create nitrogen-doped GAC with desirable surface chemical properties. Performance of all GACs was evaluated with respect to formaldehyde removal through a series of packed bed column studies. With respect to continuous formaldehyde monitoring, a method detection limit for emerging sensor technology was determined to be approximately 2 ppb[subscript v], and for relative humidity levels characteristic of indoor environments (> 40%), quantitative, continuous formaldehyde measurements less than 10 ppb[subscript v] were robust. The two commercially available GACs tested were both capable of removing formaldehyde; however, the GAC with greater density of basic surface functional groups and greater electron-donating potential (Centaur) removed twice as much formaldehyde (on a GAC mass basis) as the less basic GAC (BPL). A laboratory-prepared GAC (BPL-N) was successfully created to contain pyridinic and pyrrolic nitrogen, which was associated with increased surface density of basic functional groups, as well as with increased electron-donating potential. BPL-N exhibited better removal capacity for formaldehyde than BPL and Centaur. Furthermore, packed bed column studies of BPL-N and BPL formaldehyde removal performance yielded evidence to support the hypothesis that electron-donating potential, especially nitrogen functional groups at the BPL-N surface, promote catalytic removal of gas-phase formaldehyde via oxidation. / text

<p>In the work underlying this thesis solid-phase microextraction (SPME) was evaluated as a passive sampling technique for organophosphate triesters in indoor air. These compounds are used on a large scale as flame-retarding and plastizicing additives in a variety of materials and products, and have proven to be common pollutants in indoor air. The main objective of this work was to develop an accurate method for measuring the volatile fraction. Such a method can be used in combination with active sampling to obtain information regarding the vapour/particulate distribution in different indoor environments. SPME was investigated under both equilibrium and non-equilibrium conditions and parameters associated with these different conditions were estimated. </p><p>In <b>Paper I</b>, time-weighted average (TWA) SPME under dynamic conditions was investigated in order to obtain a fast air sampling method for organophosphate triesters. Among the investigated SPME coatings, the absorptive PDMS polymer had the highest affinity for the organophosphate triesters and was consequently used in all further work. Since the sampling rate is dependent on the agitation conditions, the linear airflow rates had to be carefully considered. Sampling periods as short as 1 hour were shown to be sufficient for measurements in the ng-μg m^-3 range when using a PDMS 100-μm fibre and a linear flow rate above 7 cm s^-1 over the fibre. </p><p>SPME under equilibrium conditions is rather time-consuming, even under dynamic conditions, for slowly partitioning compounds such as organophosphate triesters. Nevertheless, this method has some significant advantages. For instance, the limit of detection is much lower compared to 1 h TWA sampling. Furthermore, the sampling time can be ignored as long as equilibrium has been attained. In <b>Paper II</b>, SPME under equilibrium conditions was investigated and evaluated for organophosphate triester vapours. Since temperature and humidity are closely associated with the distribution constant a simple study of the effect of these parameters was performed. The obtained distribution constants were used to determine the air levels in a common indoor environment. SPME and parallel active sampling on filters yielded similar results, indicating that the detected compounds were almost entirely associated with the vapour phase</p><p>To apply dynamic SPME method in the field a sampler device, which enables controlled linear airflow rates to be applied, was constructed and evaluated (<b>Paper III</b>). This device was developed for application of SPME and active sampling in parallel.</p><p>A GC/PICI-MS/MS method was developed and used in combination with active sampling of organophosphate triesters in indoor air (<b>Paper IV</b>). The combination of MS/MS and the soft ionization achieved with methanol as reagent gas yielded high selectivity and detection limits comparable to those provided by GC with nitrogen-phosphorus detection (NPD). The method limit of detection, when sampling 1.5 m³ of air, was in the range 0.1-1.4 ng m^-3. In <b>Paper V</b>, the developed MS method was used in combination with SPME for indoor air measurements.</p><p>The levels detected in the investigated indoor environments range from a few ng to μg m^-3. Tris(2-chloropropyl) phosphate was detected at a concentration as high as 7 μg m^-3 in a newly rebuilt lecture room.</p>

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This study aimed to develop retrofitted natural ventilation options and control strategies for existing office buildings to improve thermal comfort, indoor air quality and energy consumption. For this purpose, a typical office building was selected in order to identify opportunities and constraints when implementing such strategies. Actual performance of the case study building was evaluated by conducting quantitative and qualitative field measurements including physical measurements and questionnaire surveys. Based on the actual building performance, a combination of Dynamic Thermal Simulation (using IES) and Computational Fluid Dynamics (using PHOENICS) models were built to develop appropriate natural ventilation options and control strategies to find a balance between energy consumption, indoor air quality, and thermal comfort. Several retrofitted options and control strategies were proposed and the best retrofitted natural ventilation options and control strategies were installed in the case study building. Post occupancy evaluation of the case study building after the interventions was also carried out by conducting physical measurements and questionnaire surveys. Post refurbishment measurements revealed that energy consumption and risk of overheating in the refurbished building were reduced by 9% and 80% respectively. The risk of unacceptable indoor air quality was also reduced by 60% in densely occupied zones of the building. The results of questionnaire surveys also revealed that the percentage of dissatisfied occupants reduced by 80% after intervention. Two new products including a Motorized ceiling tile and NVlogIQ , a natural ventilation wall controller, were also developed based on the results of this study.

La qualité de l’air dans les habitats est un problème majeur en Europe, où les personnes passent une grande partie de leur temps en milieu intérieur. Selon l’OMS, de nombreux habitats sont touchés par l’humidité entraînant le développement de moisissures qui ont des conséquences sanitaires et économiques.Dans ce travail, une approche globale, associant étude de terrain et expérimentations en laboratoire, a été employée pour décrire l’exposition aux bioaérosols dans des habitations dégradées par les moisissures, étudier leurs effets sur la santé des résidents et proposer une démarche diagnostique applicable aux habitats dégradés. Nous avons ainsi mis en évidence la présence récurrente de certaines espèces fongiques, notamment Aspergillus versicolor, Penicillium chrysogenum et P. crustosum, qui pourraient être utilisées comme indicateurs microbiologiques de contamination fongique de l’air intérieur. Par ailleurs les analyses statistiques ont permis de montrer des liens entre les concentrations de certaines espèces de micromycètes dans l’air et les catégories de surface contaminées proposées par l’ANSES. Des relations ont également pu être établies entre l’exposition à ces moisissures et certaines manifestations respiratoires et cutanées mentionnées chez les résidents. L’évaluation du potentiel cytotoxique des bioaérosols collectés dans les habitats dégradés a, quant à elle, permis de mettre en évidence un lien entre les réponses observées sur deux lignées cellulaires testées (pulmonaire A549 et cutanée HaCaT).D’un point de vue méthodologique, la qPCR couplée à la cytométrie en flux semble être une méthode rapide qui peut être corrélée à l’approche culturale et permet ainsi de suivre l’exposition à Aspergillus versicolor dans les habitats dégradés. Huit espèces fongiques récurrentes dans les bioaérosols ont également été sélectionnées pour une étude en enceinte climatique montrant l’impact de la température et de l’humidité relative sur la croissance et la toxinogenèse fongique. / Air quality in houses is a major concern in Europe, as people spend most of their time indoors. According to the WHO, numerous houses are exposed to dampness that can lead to mold growth, causing health and economic damages.In this work, a global approach including both field study and laboratory experimentations was used to characterize the human exposure to bioaerosols in mold-damaged houses, to study their health effects on inhabitants and to propose a diagnostic process that could be applied to mold-damaged houses. We showed the recurrence of several fungal species, specifically Aspergillus versicolor, Penicillium chrysogenum and P. crustosum, which could be used as microbial indicators of airborne fungal contamination. In addition, our statistical analyses showed relations between the concentrations of recurrent molds in air and the levels of surface contamination by molds proposed by ANSES. Statistical link has also been found between mold exposure and respiratory or cutaneous symptoms described by the inhabitants. A cytotoxic potential evaluation of bioaerosols collected in these mold-damaged houses allowed to highlight a relation between the responses observed for the two cell lines (pulmonary A549 and cutaneous HaCaT).From a methodological point of view, qPCR coupled with flow cytometry appears to be a fast and reliable method that can be correlated to cultural approach, allowing to monitor the human exposure to Aspergillus versicolor in mold-damaged buildings. Eight recurrent fungal species identified in bioaerosols were also selected for a study in a climatic chamber that showed the effects of temperature and relative humidity on fungal growth and toxinogenic potential.

Nos últimos anos tem havido um aumento no estudo da qualidade do ar interno relacionado aos sistemas de ventilação mecânica e condicionamento do ar. Isso é especialmente fundamental em hospitais, onde a transmissão da contaminação pelo ar é considerada uma das principais causas de aquisição de doenças por pacientes, profissionais de saúde e visitantes. Além disso, essas instituições por abrigarem diversos setores, cada um com uma especificidade e função, exigem diferentes condições de conforto ambiental, sob os aspectos higrotérmico e de qualidade do ar, além do acústico e luminoso. Com o objetivo de avaliar a qualidade o ar, sob os parâmetros de conforto térmico e da concentração de dióxido de carbono em ambientes hospitalares climatizados artificialmente, realizou-se uma investigação de campo em salas de espera e salas de cirurgias de uma amostra de seis edifícios hospitalares na cidade de São Paulo e região metropolitana. Para coleta dos dados foram utilizados instrumentos de monitoramento, portáteis e de elevada precisão, adequados para a realização da pesquisa. Os resultados obtidos a partir da análise desses dados apontaram relevantes problemas relacionados ao conforto e a qualidade do ar. Dentre esses problemas, destacam-se a ausência de controle do diferencial de pressão entre as salas de cirurgias e os corredores; a divergência entre as temperaturas operativas ideais para promoção do conforto térmico para grupos de pessoas com diferentes vestimentas e nível de atividade, ocupando um mesmo ambiente, no caso, as salas de cirurgias; a insuficiência de renovação de ar, especialmente nas salas de espera equipadas com o sistema de climatização do tipo split-system; além da ausência de padronização entre os critérios dos referenciais técnicos mais adotados. Sob esses aspectos, percebeu-se a necessidade de melhoria do conhecimento da interação entre os ocupantes e o ambiente, especialmente naqueles onde o controle se faz necessário para a promoção da saúde. / In recent years has been increased interest in thermal comfort and air quality of indoor environments related to mechanical ventilation systems and air conditioning. This is especially crucial in hospitals where contaminated air transmission is considered a major cause of acquiring disease for patients, health care professionals and visitors. Moreover, these institutions having different sectors, each one with a speciality and function, require different conditions of environmental comfort, in terms of hygrothermal, air quality, acoustic and luminous aspects. In order to evaluate the air quality under the parameters of thermal comfort and carbon dioxide concentration in air conditioning hospital environments, it was carried out a field investigation in waiting rooms and operating rooms in six hospitals in São Paulo and metropolitan region. For data collection were used portable monitoring devices, suitable for research. The results from data analysis indicated significant problems related to thermal comfort and indoor air quality. Among these problems, it can be highlighted the lack of the differential pressure control between the operating rooms and corridors; the divergence among the optimal operative temperatures to provide thermal comfort for different groups of people with different clothing and activity level, occupying the same environment, in this case, the operating rooms; the disregard with the air changes required, especially in waiting rooms equipped with the splitsystem; besides the lack of standardization among the technical references criteria often used. Under these aspects, it is necessary to improve the knowledge of the interaction between the occupants and the environment, especially where the environmental control is decisive to promote the health.

Ao longo de quinze meses, foram monitorados na Biblioteca Pública Amadeu Amaral, da cidade de São Carlos, SP, os níveis de temperatura, umidade relativa, ruído, intensidade luminosa, contaminação por dióxido de carbono, material particulado total (MPT) e suas frações respiráveis (MP1, MP2,5, MP7 e MP10), avaliação da taxa de ventilação e ocupação, concentração de bioaerossóis e sua identificação. Além disso, foi aplicado um questionário aos ocupantes do local com o intuito de levantar as principais reclamações e queixas relacionadas à qualidade do ar interior. Os resultados mostraram o desconforto térmico do local em todas as salas monitoradas, altos níveis de ruído proveniente do ambiente externo, inadequações relativas à iluminação do local e necessidade de uma atenção especial à taxa de ocupação do prédio. Durante alguns momentos das medições, os níveis de ruído ultrapassaram a barreira dos 80 dB(A), que é um valor bem acima do recomendado em normas, revelando-se um fator de risco para seus usuários e funcionários. Não foram encontrados problemas relacionados à contaminação biológica do local, analisando a concentração de bactérias e fungos. A taxa de ventilação possui valor adequado para o piso 1 e a concentração de gás carbônico se manteve de acordo com os padrões estabelecidos em normas. As respostas dos questionários confirmam os principais resultados encontrados para a Biblioteca, como os altos níveis de ruído, o desconforto térmico do local e as inadequações da iluminação. As recomendações são pautadas na necessidade de realização de ensaios gravimétricos da concentração de material particulado e o desenvolvimento de estudos específicos para a adoção de medidas mitigadores da poluição sonora e, também, da adequação das salas para o conforto térmico dos ocupantes. / Over fifteen months, levels of temperature, humidity, noise, light intensity, contamination by carbon dioxide, total suspended particles (TSP) and respirable fractions (PM1, PM2.5, PM7 and PM10) were monitored at the Public Library Amadeu Amaral at São Carlos, SP. Investigation of the ventilation rate and occupancy, concentration of bioaerosols and identification were also performed. In addition, a questionnaire was handed over to the occupants of the site in order to raise the main complaints related to indoor air quality. The results showed the discomfort of the place at all rooms monitored, high levels of noise from the outside environment, inadequacies relating to the site illumination and special attention to the building occupancy. During some measurements, the noise levels exceeded the barrier of 80 dB (A), which is above the recommended standards and proved to be a risk factor for its users and employees. No problems were found related to the site biological contamination, analyzing the concentration of bacteria and fungi. The ventilation rate has adequate value to the first floor and carbon dioxide concentration was maintained in accordance with the standards. The questionnaire responses confirm the main findings to the library, such as high noise levels, thermal discomfort and the illumination problem. The main recommendations are based on the need of gravimetric particulate matter investigation and development of specific studies for the adoption of mitigation measures on noise pollution and also the suitability of the rooms to the thermal comfort of occupants.