Estimating health effects from modeled air quality time series data Open Access

Abstract

Ambient air pollution is a leading risk factor for global disease burden. Epidemiological studies can contribute to improved efforts for the measurement and mitigation of the harmful health effects of air pollution. This dissertation addressed two primary research questions:

• What are the effects of the oxidative potential of ambient particulate matter on human health?
• What are the health benefits of air pollution control policies?

Oxidative potential (OP) has been proposed as a major mechanism of particulate toxicity. To answer the first research question, we estimated health associations for the OP of water-soluble fine particulate matter (PM2.5) measured using a dithiothreitol assay (OP^DTT). Daily counts of emergency department (ED) visits for several cardiorespiratory outcomes were obtained for 42 hospitals serving patients in the 5-county Atlanta metropolitan area. OP^DTT was measured for 196 days, and measured OP^DTT was positively associated with ED visits for respiratory disease, asthma, and ischemic heart disease. These associations were generally not attenuated in bipollutant models with many commonly measured pollutants.

Extending this analysis, we developed a predictive model for OP^DTT using concurrently measured air quality and meteorology variables. This predictive model was used to backcast daily OP^DTT values for 1999-2013, and we estimated health associations for these modeled OP^DTT values. Modeled OP^DTT was associated with ED visits for respiratory disease and asthma, and these associations were not attenuated in bipollutant models with PM2.5 mass.

To answer the second research question, we used counterfactual estimates for ambient pollutant levels if several policies affecting the Atlanta area were not implemented. After creating a multipollutant health effects model, these counterfactual estimates were contrasted with measured ambient pollutant levels to estimate the health impact of these policies. Greater proportions of visits were prevented in later years as effects of policies became more fully realized. Air pollution control policies were estimated to substantially prevent ED visits for respiratory disease, asthma, cardiovascular disease, and congestive heart failure.

The findings from these studies provide support for a promising measure of particle toxicity and present results which may be useful for informing future air pollution control strategies.

Table of Contents

TABLE OF CONTENTS

CHAPTER 1: INTRODUCTION..........1

CHAPTER 2: BACKGROUND..........4

2.1: General health effects of air pollution..........4

2.2: Types of air pollution epidemiologic studies..........7

2.3: References..........10

CHAPTER 3: RESEARCH QUESTION I..........18

3.1: Oxidative potential..........18

3.2: Knowledge gap addressed by current studies..........21

3.3: References..........24

CHAPTER 4: RESEARCH QUESTION II..........33

4.1: Accountability studies..........33

4.2: Health Effects Institute, Request for Applications 11-1..........39

4.3: Pollution control policies affecting the Atlanta metropolitan area..........40

4.4: Counterfactual ambient pollution level estimation..........44

4.5: Estimating number of ED visits prevented due to air pollution control programs..........47

4.6: References..........49

CHAPTER 5: STUDY DATA AND OVERVIEW..........53

5.1: SCAPE OP^DTT assay..........53

5.2: SEARCH Jefferson Street air quality data..........55

5.3: Atlanta emergency department data set..........72

5.4: Summary of study aims..........78

5.5: References..........80

6: AIM I: ASSOCIATIONS BETWEEN AMBIENT FINE PARTICULATE OXIDATIVE POTENTIAL AND CARDIORESPIRATORY EMERGENCY DEPARTMENT VISITS..........82

6.1: Abstract..........82

6.2: Introduction..........83

6.3: Methods..........86

6.4: Results..........89

6.5: Discussion..........90

6.6: Conclusions..........94

6.7: References..........100

7: AIM II: ASSOCIATIONS BETWEEN MODELED FINE PARTICLE OXIDATIVE POTENTIAL AND CARDIORESPIRATORY EMERGENCY DEPARTMENT VISITS IN A LONG-TERM TIME SERIES STUDY..........108

7.1: Abstract..........108

7.2: Introduction..........110

7.3: Methods..........112

7.4: Results..........119

7.5: Discussion..........122

7.6: Conclusion..........125

7.7: References..........137

8: AIM III: IMPACT OF AIR POLLUTION CONTROL POLICIES ON CARDIORESPIRATORY EMERGENCY DEPARTMENT VISITS, ATLANTA, GA, 1999-2013..........144

8.1: Abstract..........144

8.2: Introduction..........146

8.3: Methods..........148

8.4: Results..........158

8.5: Discussion..........161

8.6: Conclusion..........165

8.7: References..........174

9: OVERALL CONCLUSIONS..........181

About this Dissertation

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School	Laney Graduate School
Department	Epidemiology
Degree	PhD
Submission	Dissertation
Language	English
Research Field	Environmental Health Health Sciences, Epidemiology
Keyword	time series air pollution cardiovascular disease oxidative potential statistical modeling accountability respiratory disease
Committee Chair / Thesis Advisor	Tolbert, Paige, Emory University Klein, Mitchel, Emory University
Committee Members	Strickland, Matthew, University of Nevado, Reno Sarnat, Stefanie Ebelt, Emory University Flanders, W Dana, Emory University

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