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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.

Background: Particulate matter pollution has become a growing health concern over the past few decades globally. The problem is especially evident in China, where particulate matter levels prior to 2013 are publically unavailable. We conducted a systematic review of scientific literature that reported fine particulate matter (PM2.5) concentrations in different regions of China from 2005 to 2016. Methods: We searched for English articles in PubMed and Embase and for Chinese articles in the China National Knowledge Infrastructure (CNKI). We evaluated the studies overall and categorized the collected data into six geographical regions and three economic regions. Results: The mean (SD) PM2.5 concentration, weighted by the number of sampling days, was 60.64 (33.27) µg/m3 for all geographic regions and 71.99 (30.20) µg/m3 for all economic regions. A one-way ANOVA shows statistically significant differences in PM2.5 concentrations between the various geographic regions (F = 14.91, p < 0.0001) and the three economic regions (F = 4.55, p = 0.01). Conclusions: This review identifies quantifiable differences in fine particulate matter concentrations across regions of China. The highest levels of fine particulate matter were found in the northern and northwestern regions and especially Beijing. The high percentage of data points exceeding current federal regulation standards suggests that fine particulate matter pollution remains a huge problem for China. As pre-2013 emissions data remain largely unavailable, we hope that the data aggregated from this systematic review can be incorporated into current and future models for more accurate historical PM2.5 estimates.