Improved estimation of pollen exposure, mixtures, and risk of respiratory illness Restricted; Files Only

Abstract

Pollen-related illnesses affect 60 million Americans, with annual direct medical costs reaching billions of dollars. The prevalence of pollen-induced asthma and allergic rhinitis is rising, further increasing the already substantial health burden. Despite this, pollen remains an understudied environmental risk factor, with critical gaps in understanding its health effects across different regions and environmental contexts.

One of these gaps is the lack of comprehensive risk estimation across a wide range of pollen taxa and geographic regions. In Chapter 2, we conducted the largest multi-city study to date, examining associations between 21 pollen taxa and nearly 4 million emergency department (ED) visits for asthma and wheeze across 18 U.S. cities (2005–2019). Our findings provide strong evidence of associations between 16 pollen taxa and asthma/wheeze morbidity in national metaanalyses. Regional differences in effect sizes highlight the need for location-specific mitigation strategies to reduce respiratory health impacts.

Emerging research suggests that pollen and air pollution may act synergistically to exacerbate health risks, yet few studies have investigated this interaction. In Chapter 3, we assessed the effects of co-occurring pollen taxa, pollen mixtures, and their joint associations with air pollution on asthma/wheeze ED visits in Atlanta, St. Louis, New York, and San Jose (2005–2019). We found that pollen mixtures significantly contributed to asthma/wheeze morbidity in Atlanta and St. Louis, while traffic-related air pollution did not modify these associations.

Pollen exposure assessments often rely on a single monitoring site, limiting their representativeness. In Chapter 4, we expanded Atlanta’s automated pollen sensor network to exposure differences and the potential for misestimation of health burdens within the city using previously estimated relative risks from Chapter 2. We observed substantial variability in pollen concentrations across monitoring sites, with differences in total pollen counts, taxonomic composition, and estimated health burdens. Using the Marietta monitoring site counts to estimate pollen-attributable ED visits resulted in a 31% underestimation of cases, suggesting that reliance on a single site may misrepresent health impacts, particularly for vulnerable communities. Together, these findings underscore the need for tailored public health interventions to better mitigate the health risks of pollen and spatiotemporally resolved pollen monitoring.

Table of Contents

Contents

1. Introduction ..............................................................................................................................1

2. Impact of pollen on respiratory morbidity in the United States: a multi-city time series study............13

2.1. Abstract............................................................................................................................13

2.2. Introduction ......................................................................................................................15

2.3. Methods ...........................................................................................................................16

2.3.1. Pollen Data .................................................................................................................16

2.3.2. Emergency Department Visit Data .................................................................................17

2.3.4. Site Selection and Analytical Dataset Creation ................................................................17

2.3.5. Data Analysis..............................................................................................................18

2.3.6. Sensitivity Analysis .....................................................................................................20

2.4. Results .............................................................................................................................21

2.4.1. Single Site Associations................................................................................................21

2.4.2. Regional Estimates ......................................................................................................21

2.4.3. National Estimates.......................................................................................................22

2.4.4. Sensitivity Analysis .....................................................................................................22

2.5. Discussion ........................................................................................................................23

2.6. Conclusion........................................................................................................................25

2.7. Tables and Figures.............................................................................................................26

2.8. References........................................................................................................................31

3. The joint effects of pollen and air pollution on asthma morbidity in 4 U.S. locations........................38

3.1. Abstract............................................................................................................................38

3.2. Introduction ......................................................................................................................40

3.3. Methods ...........................................................................................................................42

3.3.1. Study Area..................................................................................................................42

3.3.2. Pollen Data .................................................................................................................42

3.3.3. Air Pollutant Data ........................................................................................................43

3.3.4. Emergency Department Visit Data .................................................................................44

3.4. Results .............................................................................................................................46

3.4.1. Descriptives................................................................................................................46

3.4.2. Pollen-Asthma Associations using a Traditional Approach................................................47

3.4.3. Pollen-Asthma Associations using a Mixtures Approach...................................................48

3.4.4. Modification of Pollen-Asthma Associations by Air Pollution ...........................................49

3.4.5. Sensitivity Analysis .....................................................................................................49

3.5. Discussion ........................................................................................................................50

3.6. Conclusion........................................................................................................................53

3.7. Tables and Figures.............................................................................................................54

3.8. References........................................................................................................................59

4. Assessing the Distribution and Health Burden of Pollen in Atlanta, GA with Automated Pollen Sensors .................................................................................................................................................66

4.1. Abstract............................................................................................................................66

4.2. Introduction ......................................................................................................................68

4.3. Methods ...........................................................................................................................70

4.3.1. Pollen Sense Sampler...................................................................................................70

4.3.2. Study Period and Sites..................................................................................................70

4.3.3. Statistical Analysis.......................................................................................................71

4.3.4. Health Impact Function ................................................................................................72

4.4. Results .............................................................................................................................73

4.6. Discussion ........................................................................................................................77

4.7. Conclusion........................................................................................................................80

4.8. Tables and Figures.............................................................................................................82

4.9. References........................................................................................................................89

5. Conclusion..............................................................................................................................94

6. Appendices .............................................................................................................................98

6.1. Appendix: Chapter 2 ..........................................................................................................98

6.2. Appendix: Chapter 3 ........................................................................................................105

6.3. Appendix: Chapter 4 ........................................................................................................107 

About this Dissertation

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School	Laney Graduate School
Department	Environmental Health
Degree	Ph.D.
Submission	Dissertation
Language	English
Research Field	Health Sciences, Public Health Health Sciences, Epidemiology Environmental Health
Keyword	pollen air pollution public health environmental health asthma epidemiology allergies
Committee Chair / Thesis Advisor	Stefanie Ebelt, Emory University Noah Scovronick, Emory University
Committee Members	Howard Chang, Emory University Yang Liu, Emory University

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