Ambient exposure to fine particulate matter (PM2.5) and ground-level ozone (O3) is identified as a leading risk factor for global disease burden. A major limitation to advancing our understanding of the cause and impacts of air pollution is the lack of observations with the spatial and temporal resolution needed to observe variability in emission, chemistry and population exposure. Satellite remote sensing, which fills a spatial gap in ground-based networks, is playing an increasingly important role in atmospheric chemistry. This thesis exploits satellite remote sensing observations to: (1) estimate human exposure to PM2.5 from remotely sensed aerosol optical properties; (2) identify the chemical regimes of surface O3 formation using satellite observations of O3 precursors. In the first part, we use a forward geophysical approach to derive PM2.5 distributions from satellite AOD at 1 km2 resolution over the northeastern US by applying relationships between PM2.5 and AOD simulated from a regional air quality model (CMAQ). We use multi-platform ground, airborne and radiosonde measurements to quantify multiple sources of uncertainties in the satellite-derived PM2.5. We find that uncertainties in satellite-derived PM2.5 are largely attributed to the varying relationship between PM2.5 and AOD that depends on the aerosol vertical distribution, speciation, aerosol optical properties and ambient relative humidity. To assess the value of remote sensing to improve PM2.5 exposure estimate, we compile multiple PM2.5 products that include information from remote sensing, ground-based observations and models. Evaluating these products using independent observations, we find the inclusion of satellite remote sensing improves the representativeness of surface PM2.5 mostly in the remote areas with sparse monitors. Due to the success of emission control, PM2.5-related mortality burden over NYS decreased by 67% from 8410 (95% confidence interval (CI): 4, 570 – 12, 400) deaths in 2002 to 2750 (95% CI: 700 – 5790) deaths in 2012. We estimate a 28% uncertainty in the state-level PM2.5 mortality burden due to the choice of PM2.5 products, but such uncertainty is much smaller than the uncertainty (130%) associated with the exposure-response function. The second part of the thesis focuses on ground-level O3. O3 production over urban areas is non-linearly dependent on the availability of its precursors: nitrogen oxides (NOx) and volatile organic compounds (VOCs). A major challenge in lowering ground-level O3 in urban areas is to determine the limiting species for O3 production (NOx-limited or VOC-limited). We use satellite observations of NO2 and HCHO to infer the relative abundance of NOx versus VOCs, thus to identify the O3 chemical regime. We first use a global chemical transport model (GEOS-Chem) to evaluate the uncertainties of using satellite-based HCHO/NO2 to infer O3 sensitivity to precursor emissions. Next, we directly connect this space-based indicator, retrieved consistently from three satellite instruments, to spatiotemporal variations in O3 recorded by on-the-ground monitors from 1996 to 2016. The nationwide emission reduction has led the O3 formation over U.S. urban areas to shift from VOC-limited to NOx-limited regime. Urban O3 monitors reveal trends consistent with this regime transition. Nonetheless, it is a major challenge for these retrievals to accurately depict day-to-day variability within urban cores. TROPOspheric Monitoring Instrument (TROPOMI) which launched in 2017, offers an unprecedented view to infer O3 chemistry at fine spatial and temporal scales. As an example, we use TROPOMI HCHO/NO2 to identify short-term changes in O3 sensitivity during the California Camp Fire. We find that the emissions from wildfires lead to NOx-saturated ozone formation near the fire source but NOx -limited conditions downwind. This thesis bridges basic research in atmospheric chemistry, which advances the state-of-science related to O3 and PM2.5 pollution from urban to global scales, and applied research in air quality management and public health, by quantifying the health benefits of emission control, and informs policymakers on which emission reductions to focus so as to maximize the cost-effectiveness of pollution controls. We show how space-based measurements can complement in situ networks and model simulations by providing information on the spatial heterogeneity and temporal evolution of PM2.5 exposure and O3 chemical regimes, which will lay the scientific foundation for interpreting future products retrieved from upcoming geostationary platforms.

High PM2.5-related mortality and morbidity has become a public health concern in China. To date, there have been few studies investigating individual implementation and use of protective behaviors to counter outdoor PM2.5 air pollution levels in China. This study, therefore, aimed to investigate adults’ attitudes toward evidence-based protective behaviors against outdoor PM2.5 air pollution, the results of which might inform health educators and health promotion specialists about what they should emphasize when educating communities about protective behaviors in the PM2.5 air pollution days. Utilizing the purposing sampling method, a WeChat-based survey was conducted among 300 adult participants living in B residential area in Yuhuatai district of Nanjing, which is a representative city of high urbanization level and PM2.5 air pollution in China. The survey included total 16 items assessing participants’ background information, attitudes toward four evidence-based protective behaviors against PM2.5 air pollution, and knowledge regarding possibly effective protective approaches specifically related to Chinese medicine in the PM2.5 air pollution. The results showed that the importance adults in Nanjing attached to wearing N95 respirator when walking outside, putting air filter (HEPA) at home, and avoiding unprotected outdoor sports activities in the PM2.5 air pollution was greater than closing all the doors, windows, and many openings in the PM2.5 air pollution. Regarding comparison of attitudes between pre- and post-controlled COVID-19 periods, the value adults gave to closing all the doors, windows, and many openings in the PM2.5 air pollution was higher during pre-COVID-19 period, whereas the opposite of circumstance took place when referring to other three protective behaviors. Regarding comparison of attitudes between biographic variables, adults aged 18-50 (including 50) attached greater importance to all the four protective behaviors than those aged 50+. In addition, adults having the habit of checking daily AQI ranked the behaviors of avoiding outdoor sports activities and wearing N95 respirator when walking outside in the PM2.5 air pollution in a higher position than those not. Implications for future research and practice are discussed, based on a critique of the present work.

Air pollution is one of the leading environmental problems of the 21st century, and the rise of global urbanization has increasingly exacerbated air pollution’s public health impact. Existing epidemiologic studies have tackled the relationship between air pollution and health from a variety of perspectives, but many areas of research remain lacking, including studies originating from developing countries, the assessment of exposure windows and sensitivity of modeling choices, and a better understanding of the climate change impacts on air pollution and health. In this dissertation, I address all of the issues mentioned above. Chapter 1 formally introduces the topics of this dissertation and summarizes background information on several major air pollutants. It then provides an overview of existing research on air pollution epidemiology and describes key knowledge gaps. In Chapter 2, we conduct a systematic review of the scientific literature for data on fine particulate matter (PM2.5) in China, where historical PM2.5 data are not widely available prior to 2013. Using the 574 PM2.5 measurements we identified from the literature, we detected differences in PM2.5 levels across both geographic and economic regions of China. In Chapter 3, we investigate the associations between short- and intermediate-term exposure of nitrogen dioxide (NO2) and mortality in 42 counties in China from 2013 to 2015, and find evidence of significant associations up to seven days prior to exposure. In Chapter 4, we investigate the association between PM2.5 and hospitalizations in New York State using five separate exposure datasets from 2002 to 2012. We find that despite some fluctuations in effect estimates, the majority of models yielded consistently significantly harmful associations. In Chapter 5, we utilize a global chemistry-climate model to project ozone levels in 2050 under a variety of emissions scenarios and quantify the mortality impact associated with changes in ozone concentrations between 2015 and 2050 according to each scenario. We find that under climate change alone and adherence to current legislation, ozone-related deaths would increase. However, under a best-case scenario of maximum technologically feasible reductions in emissions, over 300,000 premature deaths related to ozone can be avoided. Finally, Chapter 6 summarizes the findings of this dissertation and discusses potential directions in future research. While much work remains to be done, this dissertation work takes an important step forward in closing existing knowledge gaps in the field of air pollution epidemiology. More importantly, we hope that our work sends a strong public health message on the importance of continuing research on air pollution and health.

Climate change is already harming public health through warmer, more erratic weather and many downstream consequences. Research can support climate change adaptation by characterizing climate-related exposures, identifying vulnerable populations, and identifying effective interventions. Furthermore, the main source of greenhouse gas emissions, fossil fuel combustion, also produces air pollutants such as fine particulate matter (PM2.5) that directly harm human health. In this dissertation my colleagues and I have examined the effects of short-term temperature exposure on myocardial infarction and stroke to inform adaption (Chapters 1 to 3) and leveraged multiple exposure models to estimate annual PM2.5 concentrations and quantify uncertainty (Chapter 4). To examine the effects of short-term temperature exposure, we conducted case-crossover analyses using an administrative dataset of hospitalizations in New York State. For PM2.5 prediction and uncertainty characterization, we applied a flexible ensemble approach to leverage seven already-developed PM2.5 models. Overall, we found that warmer hourly temperatures and greater daily temperature variability increased the risk of ischemic events, and lower hourly temperatures increased the risk of hemorrhagic stroke. The ensemble model showed high predictive accuracy, demonstrating the strength of this approach, and we observed greatest uncertainty in the Pacific Northwest and southeast coast. The methods applied in this dissertation can be applied to other exposures and in different settings to further quantify the risks of climate impacts and improve air pollution assessment. Future research should examine the joint impacts of multiple weather factors, strategies to protect people in group housing from extreme weather, measurements and models to reduce uncertainty of air pollution exposures, and propagate exposure uncertainty into health models. However, the need for further research should not delay climate action today.

Chapter 1. Background: Asthma is the most common chronic childhood disease and is characterized by recurrent airway obstruction, bronchial hyper-responsiveness, and airway inflammation. Asthma is the leading cause of childhood hospitalization and school absenteeism in the United States. The associations between adverse respiratory effects and exposure to indoor nitrogen dioxide (NO2) and other byproducts of combustion such as particulate matter (PM) in particular ultrafine particulates (UFP), Ozone (O3) and Sulfur Dioxide (SO2), have been the focus of many epidemiological studies in recent years. Indoor exposure to NO2 and other pollutants from combustion may increase the risk of acute and chronic respiratory disease, reduce lung function, initiate and exacerbate asthma in children. The levels of exposure to NO2 indoors are of public health concern because children spend nearly 70% of their time indoors at home. According to the 2010 US Census report, approximately 39% of US households use natural gas for cooking, and the primary source of residential NO2 is a gas-fuel cooking appliance. Indoor levels of NO2 where NO2 sources are present can be much higher than outdoors, where the primary source of NO2 is vehicular traffic. Epidemiological studies in developed countries suggest that gas stoves used for cooking and/or heat are associated with an increased risk of asthma and respiratory symptoms in children. While there are numerous, epidemiological studies supporting an association between increased NO2 levels and gas stoves and asthma symptom severity in children, there are other studies that have examined the relationship in homes that did not observe significant associations. A better understanding of how NO2 and other indoor environmental (e.g., environmental tobacco smoke (ETS), allergens) exposures contribute to asthma morbidity in inner city preschool children will allow interventions to more effectively designed and implemented. To date, there are conflicting results on the role of exposure to indoor NO2 and its association with new-onset asthma in young inner-city children. The recent studies assessing the effects of indoor NO2 on asthma morbidity were limited to inner-city children, largely older, who were diagnosed with asthma. A gap in knowledge remains regarding the role indoor NO2 plays on the development of asthma in children not previously diagnosed. The scientific and public health rationale for conducting this dissertation was to describe the association of exposure to indoor NO2 and primary sources with the initiation and exacerbation of asthma symptoms among pre-school children with and without diagnosed asthma. The data analyzed in the current research come from a larger study of Endotoxin, Obesity, and Asthma (EOA) in the New York City Head Start Program, funded in the summer of 2002. The primary research objective of that study was to identify modifiable risk factors associated with asthma and asthma persistence among preschool children from low-income families living in select New York City neighborhoods with high pediatric asthma hospitalization rates. We conducted a cross-sectional analysis of data collected from the study questionnaire and home visit sampling at study enrollment. The analyses were performed in two phases: the first phases used data collected at study enrollment and the second phase used data collected 12-months after study baseline. Henceforth, the dissertation will refer to the first analyses as the baseline study and the second as the follow-up study. The research evaluated the association of NO2 exposure with asthma status among New York City Head Start children with and without asthma at study enrollment and with respiratory symptoms among children with asthma at 12-month follow-up. Chapter 2. Baseline Study: We conducted a cross-sectional analysis of data collected from the study questionnaire and home visit sampling at study enrollment. Specifically, the research sought to evaluate the association of NO2 exposure with asthma status among New York City Head Start children with and without asthma at study enrollment and with respiratory symptoms among children with asthma at enrollment. A total of 503 children were included in the baseline study. A total of 105 children (20.9%) met the criteria for both asthma and allergy, and 67 (13.3%) met the criteria for asthma alone. Girls made up 51.7% and boys, 48.3% of the 503 study participants. Descriptive analyses suggested that asthma/allergy status was associated with: male gender, non-Mexican ethnicity/national origin, presence of a smoker in the child’s home, number of smokers in the child’s home, self-reported parental history of asthma, mother’s education level and sensitization to one or more of the four allergens. Logistic regression models were used to investigate the magnitude and direction (as well as trend) of the association between childhood asthma and indoor NO2 sources in the child’s home. Chapter 3. Follow-up Study: Our follow-up study involved the analysis of the 12-month follow-up data from the study of Endotoxin, Obesity, and Asthma in the New York City Head Start Program funded in the summer of 2002. We focused on assessing the magnitude and direction of the associations of exposure to indoor NO2 levels (based on baseline NO2 measurements) with children’s asthma status and with symptom severity among asthmatics at 1-year follow-up. For the follow-up study, we categorized children by whether their asthma status had changed since baseline. Descriptive analyses were performed looking at key characteristics by “change in asthma status.” Children’s asthma status at baseline and at follow-up, were based on responses to the questionnaire. We analyzed indoor NO2 level measurements at baseline in relation to asthma outcomes on follow-up. We did not have enough data on NO2 levels at follow-up to analyze them in relation to asthma status on follow-up. Unless the family had relocated since baseline and/or reported changes since baseline in the use of gas appliances or the number of smokers in the home, we assumed that baseline NO2 levels in the participating children’s homes were reasonable proxies for current exposures. We looked at the number of children who moved since baseline and whether the move (for example, looking at gas stove status, age of new building) may have impacted indoor NO2 levels. Of the 503 children who were included in the baseline analyses, 47.3% had data on asthma status on follow-up. A total of 238 children (111 male, 127 female) were grouped into the four mutually exclusive outcome categories: 122 (51.3%) did not have asthma at baseline or on follow-up, 34 (14.3%) had asthma on follow-up but not at baseline, 65 (27.3%) had asthma at baseline but not on follow-up, and 17 (7.1%) had asthma at baseline and on follow-up. The mean age at 1-year follow-up was 59.5 months (6.95), and neither age nor gender was associated with asthma. The distribution of ethnicity/national origin among the 238 children remained the same as at baseline; no one ethnicity group experienced disproportionate loss to follow-up, and asthma status remained associated with non-Mexican ethnicity/national origin, although 44.1% with new-onset asthma were of Mexican background. Asthma was also associated with self-reported parental history of asthma and allergy in children, but nearly 80% of children with new-onset asthma had no such parental history of asthma. More parents of children with new-onset (35.3%) or persistent asthma (23.5%) than of other children reported making efforts to reduce risk factors or triggers for asthma exacerbations in the past 12 months. Chapter 4. Dissertation Conclusion : The primary objective of the dissertation research was the examination of the relationship between asthma and asthma severity and exposure to gas cooking and residential NO2. In both our baseline and 12-month follow-up studies, exposure to indoor NO2 was represented by the baseline measurement of NO2 and the NO2 surrogate, gas stove. Asthma status of children was based on parental responses on the questionnaire regarding asthma symptoms and urgent care visits due to respiratory distress over the course of each 12-month period prior to the conducting study questionnaires. For both studies, we did not find an association between exposure to NO2 levels at baseline and asthma status or severity. Our findings contradict the results of most recent studies of both NO2 levels and residential sources of NO2 and their effects on asthma symptoms in very young children. However, it remains difficult to compare our results we those of previous published studies because those studies primarily focused on children who were diagnosed with asthma, whereas our research included preschool aged children with and without asthma. Based on our findings and the fact they conflict with other epidemiological studies, of which there were also conflicting results, we feel that the relationship between asthma symptoms and NO2 exposures remains ambiguous. The lack of consistent results of epidemiological research raises questions that should be the focus of future epidemiological studies. What are the roles of co-pollutants and co-risk factors? Does NO2 work alone or in concert with other indoor pollutants? There exists a real lack of understanding on the possible synergistic effects of exposure to NO2 and other combustion byproducts. Important to furthering our knowledge of the role of exposure to indoor NO2 and asthma is determining whether NO2 acts as a surrogate for co-pollutants that are considered risk factors for asthma and other respiratory conditions. Another focus of future indoor pollution studies should be the development of effective methods and technologies for measuring the constituents of the complex mixture of pollutants in indoor air; these methods and technologies can then be applied in personal monitoring of exposure to indoor pollutants in epidemiological studies that would help to determine with much more accuracy the effects of individual indoor pollutants on asthma and other respiratory symptoms. This knowledge would help in the development of more effective public health and environment policies towards reducing the burden of childhood asthma.

Open burning of biomass and anthropogenic waste is a major source of aerosols at the biosphere-atmosphere interface, yet its impact on Earth’s climate and air quality is not fully understood due to the intricate feedbacks between the natural environment and human activities. Earth system models (ESMs) are a vital tool in the study of these aerosol-biosphere-atmosphere interactions. ESMs allow the estimation of radiative forcing and climate impacts in terms of changes to temperature and precipitation as well as the attribution to natural or anthropogenic drivers. To provide coherent results, however, ESMs require rigorous development and evaluation against observations. In my work I use the NASA-GISS ESM: ModelE. One of its strengths lie in its detailed aerosol schemes that include microphysics and thermodynamic partitioning, both necessary for the simulation of secondary inorganic aerosols. To overcome one of ModelE’s weaknesses, namely its lack of interactive biomass burning (BB) emissions, I developed pyre: ModelE’s interactive fire emissions module. pyrE is driven by flammability and cloud-to-ground lightning, both of which are calculated in ModelE, and anthropogenic ignition and regional suppression parameterizations, based on population density data. Notably, the interactive fire emissions are generated from the flaming phase in pyrE (fire count), rather than the scar left behind (burned area), which is commonly used in other interactive fire modules. The performance of pyrE was evaluated against MODIS satellite retrievals and GFED4s inventory, as well as simulations with prescribed emissions. Although the simulated fire count is bias-high compared to MODIS, simulated fire emissions are bias-low compared to GFED4s. However, the bias in total emissions does not propagate to atmospheric composition, as pyrE simulates aerosol optical depth just as well as a simulation with GFED4s prescribed emissions. Upon the development and evaluation of the fire-aerosol capabilities of ModelE, I have utilized it, with the EVA health model, to study the health impacts of outdoor smoke in 1950, 2015, and 2050. I find that chronic exposure to aerosols (PM2.5) is the main driver of premature deaths from smoke exposure, yet by 2050, acute exposure to ozone, formed downwind of BB smoke plumes, is projected to cause more premature deaths than exposure to PM2.5. I estimate the annual premature deaths from BB and waste burning (WB) smoke in 1950 to be ~41,000 and ~19,000, respectively, and in 2015 to be ~310,000 and ~840,000, respectively. By 2050 I project 390,000 and 1.5 million premature deaths from BB and WB respectively. In light of the growing impact of WB smoke exposure I identify the need to scale up viable waste management practices in regions of rapid population growth.

Indiana University-Purdue University Indianapolis (IUPUI) / Objective: "The purpose of this research is: Study the use of Moderate Resolution Imaging Spectroradiometer (MODIS) data in retrieving the aerosol optical depth (AOD) over Indiana State at high resolution of 500 meters. Examine the potential of using the resulted AOD data as an indicator of particulate air pollution by comparing the satellite derived AOD data with the ground measurements (provided from the continuous air monitors available over the study area). If an association should be found, AOD data would be used to map particulate matter (PM) concentration. Assess current and future ambient concentrations of air pollutants in the State of Indiana using the AOD."

An energy transition can be defined as the adoption of a new primary energy system. As such, it is a structural change that implies a broad shift in technologies and behaviors in order to replace one source of energy with another. Energy transitions motivated by economic, climate, and/or health goals are taking place everywhere in the world. Air pollution, a consequence of fossil fuel-based and solid fuel-based energy use among other sources, is the largest environmental health risk accounting for 6.4 million premature deaths annually. Given the health implications of our energy systems and the social drivers of energy use, access, and burden, energy transitions have the potential to impact health outcomes and associated disparities in a context-dependent manner. The research presented in this dissertation has two objectives: 1) to evaluate the distribution of benefits from energy transitions in the United States (US) and in Ghana; 2) to identify and characterize health outcomes that are relevant to these transitions but are currently understudied. Chapters 2 and 3 are anchored in the US energy policy context. Chapter 2 focuses on the transition away from coal as the primary source of energy in the US and its implications for particulate matter pollution and preterm births. Leveraging a novel dispersion model, I assessed the association between coal PM2.5 and preterm birth rates along with effect modification by race/ethnicity. We observed a positive non-linear relationship between coal PM2.5 and preterm birth rate, which plateaued at higher levels of pollution. The findings of this study suggest that the transition away from coal may have reduced preterm birth rates in the US, but that the association was stronger among non-Hispanic White women compared to non-Hispanic Black women. In Chapter 3, I use a mixed-methods framework to evaluate the first pilot of gas-to-electric stove transition in low-income housing in the US. Through a collaboration with a community-based environmental justice group in New York City, we monitored indoor air quality in participants homes pre- and post-intervention, conducted controlled cooking tests, and carried out focus groups to characterize their experience. Post-intervention, daily NO2 concentrations were 46.3% (95% CI: -67.8%, -10.3%) lower in the intervention arm compared to the control arm. Participants were unanimously pleased with the transition, which had simultaneously improved their cooking experience and partially addressed energy insecurity concerns that plagued their building. Chapters 4 and 5 contribute to the characterization of the health implications associated with Ghana’s commitment to increase access to liquified petroleum gas (LPG) nationally. In Chapter 4, we aimed to describe the country-level incidence of severe cooking-related burns by fuel type in use and to identify effect modifiers. We conducted a nationally representative (n = 7,389) household energy use survey in all 16 regions of Ghana. The incidence rate (95% CI) of cooking-related burns per 1000 person-years among working age females was 8.3 (7.2; 12.0) per 1000 person-years, which was 8 times higher than that of working age males. Among adults, the odds of experiencing a cooking-related burn were doubled among solid fuel users compared to primary LPG users. In Chapter 5, we aimed to understand the effect of an LPG intervention on personal exposure to household air pollution in a peri-urban setting of Ghana and to characterize the distribution of benefits between male and female household members quantitatively and qualitatively. The difference-in-differences results suggested a reduction in exposure to carbon monoxide due to the intervention (-14.2%, 95% CI: -44.1%, 31.6%), which might have benefited male and female participants to the same extent. Importantly, focus group discussions suggested that the ability that LPG affords to cook “on demand” could negatively impact intra-household dynamics and expectations in a way that has not been previously documented. Taken together, our findings from two distinct socioeconomic contexts, highlight the non-uniform distribution of benefits from energy transitions, especially when benefits that are not mediated by air pollution are considered. These results contribute to the understanding that social drivers of inequities should be integrated in the design of energy policies and interventions aimed at generating equitable outcomes. Future directions include a detailed characterization of the context-dependent relative contributions of indoor and outdoor air pollution sources as well as a more systematic integration of quantitative and qualitative methods in policy evaluation.

Recent and past events in the South Durban Basin (SDB) have highlighted the possible connection between perceived air pollution concerns and deteriorating health. The aim of this study is to explore how the SDB community perceives air pollution and if this can be related to some of the health problems that are experienced in these communities. The ultimate aim is to determine whether the respondents connect air pollution to specific illnesses and also how they perceive the actions used to combat air pollution and its negative health impacts. This information is gathered through a questionnaire conducted in various study areas both within and outside the SDB, then compared with demographic variables. This is done to determine if perception is related to direct industrial activity or if there are other factors influencing results. Variables such as race and level of education had little impact on the results. The results showed that areas within the SDB experience a high neighborhood satisfaction despite the current general belief of air pollution being connected to ill health. The control areas outside of the SDB support theories of gender and race and its relationship to air pollution, currently presented by researchers in the perception field. Strong associations’ do exist between general environmental satisfaction and gender. Perception of current legal enforcement is exerting a strong effect on air pollution perception formation. Vitally important is the connection of daily concrete experiences of air pollution with the lack of transparency and communication between industry and communities. It is resulting in the current perception of illness being connected to tangible air pollution. The aim is to further future studies on establishing links between health and air quality. Gaining insight from the study of public risk perceptions based on local knowledge and experience in particular places, will help shape the role of environmental policy and management response systems. / Geography / M.A. (Geography)

published_or_final_version / Community Medicine / Master / Master of Philosophy