Date of Award

Fall 1-1-2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Forestry and Environmental Studies

First Advisor

Bell, Michelle

Abstract

Climate change, the defining environmental crisis of our time, has been shown to impact concentration, distribution, and composition of tropospheric air pollutants, including particulate matter. Economic patterns greatly shape the generation of particulate matter as well as greenhouse gases that enhance climatic changes. Substantial evidence shows that exposure to fine particulates, particulate matter with aerodynamic diameter <2.5 µm (PM2.5), contributes to premature mortality and morbidity. These detrimental health outcomes have been shown to be experienced unequally across population groups, with disparities in the level of exposure and in the magnitude of health response for marginalized populations that have higher vulnerability to air pollution exposure. It is also possible that these health responses are not static, but dynamic over time due to changes in population health and composition of air pollution exposures, warranting deeper investigation into the directionality and shape of these health responses. Modeling potential future energy scenarios by using existing knowledge on health responses to air pollutants allows researchers and policymakers to understand how changes to air pollution can impact population health before policies are implemented. Thus, inclusion of appropriate modelling techniques and analyses of energy policy impacts is essential to understanding health impacts from climate mitigation and adaptation across population groups within the United States. This dissertation contributes to the growing knowledge base on climate mitigation, health co-benefits from air pollution concentration changes and health response changes across time to air pollution exposures. Chapter two presents work investigating whether energy policies that aim to reduce greenhouse gas emissions have a secondary impact of reducing health burden in the United States (U.S.) and if any changes to mortality and hospitalizations differ across subpopulations. I explored four future sector-specific energy policy scenarios (electrification of ports and marine shipping, low long-term natural gas pricing, high electric vehicle uptake, and innovations in building energy efficiency) and a business-as-usual scenario to determine how changes to ambient PM2.5 levels impact health within the continental U.S. by region, race/ethnicity, urbanicity, and income. I also investigated how methodological assumptions impact findings. I found projected avoided premature mortalities from energy transition policies range from 67,011 (95% CI: 45,692, 82,397) to 81,003 (55,286, 99,532) individuals in 2050 and 11,577 (1,332, 19,918) to 13,552 (1,560, 23,303) avoided cardiorespiratory hospitalizations in 2050, showing substantial health co-benefits from greenhouse gas mitigation policy implementation. These benefits vary by region and subpopulation, with Black, suburban, and less wealthy Americans experiencing the highest percent reduction in mortalities across all energy policy scenarios. Analysis into how population assumption specificity (such as using race-specific incidence rates instead of total population rates) influences the results proved that more specific population assumptions can make substantial differences to overall health projections. This research demonstrates the vast health benefits of climate mitigation strategies and how they differ across subpopulations, with some environmental justice populations benefiting more relative to the overall population. In chapter three, I investigated how PM2.5-mortality associations vary over time (2001-2016) in North Carolina and Michigan, while considering how temporality of these associations varies by sociodemographic variables. Results indicate that the direction of PM2.5– mortality health effects varies by location. The odds ratio (OR) for mortality per 10?g/m3 PM2.5 differed across time from 2001-2008 to 2009-2016, increasing by 0.28% in Michigan and decreasing 0.78% in North Carolina. Non-linear models show steadily increasing PM2.5-mortality odds over time for Michigan but an “S” shape for North Carolina. I also found suggestive evidence of widening disparities in PM2.5-mortality odds over time by age, race/ethnicity, urbanicity, sex, and education, although the magnitude of those changes varies across subpopulations and state. This research shows that mortality impacts of PM2.5 are changing over time, with different trends by location and subpopulation, potentially exacerbating environmental justice. This dissertation research underscores the importance of analysis to determine sociodemographic population health disparities when modeling co-benefits of energy and air pollution policies as overall estimates may obscure important differences across subpopulations. Better projections on local health effects on vulnerable communities can enhance equity considerations for climate mitigation actions, as well as provide a more holistic analysis on benefits of cost to implement versus avoided exposure and health costs. Further, this research shows that concentration-response functions may vary temporally and that such trends vary across location. This suggests that applications of historical concentration-response estimates may be obscuring the actual health impact on populations through over- or underestimates of health responses to a certain level of exposure. Improvements in the methodological assumptions of exposure and health response by introducing temporal variation provide researchers with a more accurate representation of the association between air pollution and health, which should be more widely considered in epidemiologic research. These results can inform policymakers and public health professionals in evaluating which communities are at highest risk from particulate exposures in the present day and into the future, especially in relation to temporal trends and projected changes in emissions, particulate composition, and population vulnerability.

Download

Share

COinS