nm u Ottawa L'Universite canadienne Canada's university TTTTT FACULTE DES ETUDES SUPERIEURES 1^=1 FACULTY OF GRADUATE AND ET POSTOCTORALES U Ottawa POSDOCTORAL STUDIES L'UniversihS canndienne Canada's university Nawal Farhat AUTEUR DE LA THESE / AUTHOR OF THESIS M.Sc. (Epidemiology) "G"RADE7DEGREE Department of Epidemiology and Community Medicine F7cuItTEC6LE7DEPA^ The Association of Ozone and Fine Particulate Matter with Mortality and Hospital Admissions in 12 Canadian Cities TITRE DE LA THESE / TITLE OF THESIS Daniel Krewski „.„_„„..„.^ Richard Burnett & Tim Ramsay EXAMINATEURS (EXAMINATRICES) DE LA THESE/THESIS EXAMINERS Yue Chen James Gomes Gary W. Slater Le Doyen de la Faculte des etudes superieures et postdoctorales / Dean of the Faculty of Graduate and Postdoctoral Studies The Association of Ozone and Fine Particulate Matter with Mortality and Hospital Admissions in 12 Canadian Cities Nawal Farhat Department of Epidemiology and Community Medicine Faculty of Medicine University of Ottawa Ottawa, Canada February 2009 Thesis submitted to the Faculty of Graduate and Postdoctoral Studies in partial fulfillment of the requirements for the Master of Science degree in Epidemiology © Nawal Farhat, Ottawa, Canada Library and Archives Bibliotheque et 1*1 Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington OttawaONK1A0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-59905-1 Our file Notre reference ISBN: 978-0-494-59905-1 NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library and permettant a la Bibliotheque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par I'lnternet, preter, telecommunication or on the Internet, distribuer et vendre des theses partout dans le loan, distribute and sell theses monde, a des fins commerciales ou autres, sur worldwide, for commercial or non­ support microforme, papier, electronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondares ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. ••I Canada ABSTRACT Many recent epidemiological studies have linked health effects with short-term exposure to air pollution levels commonly found in North America. The association of ozone and fine particulate matter with mortality and hospital admissions in 12 Canadian cities was explored in a time-series study. City- specific estimates were obtained by Poisson regression models adjusting for the confounding effects of seasonality and temperature. Estimates were then pooled across cities using the inverse variance method. Results suggest significant associations across all outcomes except cardiovascular hospital admissions. Generally, stronger associations were found among the elderly. Effect estimates were robust to adjustment for seasonality confounding but were sensitive to lag structures. Considering the large population exposed to air pollution, reductions in ozone and particulate matter would lead to considerable health benefits. To my parents... ACKNOWLEDGEMENTS I would like to thank my supervisor Dr. Daniel Krewski for his guidance and support during the course of my master's project. I would also like to thank my co-supervisors, Dr. Timothy Ramsay and Dr. Richard Burnett, for their valuable contributions and advice. On a personal note, I would like to express my appreciation to my family who has provided assistance in numerous ways. I am grateful to my sister and my brother-in-law for their support, inspiration and encouragement to pursue graduate studies. IV TABLE OF CONTENTS ABSTRACT II ACKNOWLEDGEMENTS IV TABLE OF CONTENTS V LIST OF FIGURES VII LIST OF TABLES X ACRONYMS/ ABBREVIATIONS XII 1 INTRODUCTION 1 1.1 Background 2 1.2 Objectives 4 1.3 Air pollutants 4 1.3.1 Ozone 4 1.3.2 Particulate Matter 5 1.3.3 Regulation In Canada 7 1.3.4 Health Effects Of Ozone And Pm25 9 2 LITERATURE REVIEW 11 2.1 Study designs 11 2.1.1 Cohort studies 11 2.1.2 Time-series studies 12 2.2 Statistical Methods in Times-series 13 2.3 Findings of time-series studies 24 2.3.1 Major Multi-city Studies 24 2.3.2 Other recent studies 26 3 MATERIALS AND METHODS 35 3.1 Study locations 35 3.2 Description of databases 35 3.2.1 Exposure data 35 3.2.2 Mortality and hospitalization data 36 3.2.3 Ecologic covariates 37 3.3 Statistical analyses 37 3.3.1 City-specific estimates 38 3.3.2 Combined estimates 41 3.3.3 Effect modification 42 4 RESULTS 43 4.1 Summary statistics 43 4.1.1 Health outcomes 43 4.1.2 Air pollution and weather 45 4.1.3 Ecologic covariates 48 4.2 Study results 50 4.2.1 Degrees of freedom for seasonality control 50 4.2.2 Lag structures 57 4.2.3 Ozone effect estimates 65 4.2.4 PM2.5 effect estimates 67 4.2.5 Summary of effect estimates 72 4.2.6 Two pollutant models 73 4.2.7 Effect modification 83 5 DISCUSSION 85 5.1 Summary of findings 85 5.1.1 Effect of degrees of freedom for seasonality 85 5.1.2 Effect of lag structure 87 5.1.3 Health effects of ozone 88 5.1.4 Health effects of PM2.5 91 5.1.5 Two pollutant models 93 5.1.6 Effect modification 94 5.1.7 Biological mechanisms 97 5.2 Methodological considerations 98 5.2.1 Strengths 98 5.2.2 Potential Limitations 99 5.3 Public health implications 102 6 CONCLUSION 104 REFERENCES 105 APPENDIX A -ADDITIONAL TABLES AND FIGURES 113 APPENDIX B -PERMISSION TO REPRODUCE COPYRIGHTED MATERIAL 120 APPENDIX C -DETAILED RESULTS 122 VI LIST OF FIGURES Figure 1 Air pollution and mortality during the 1952 London Smog. 3 Figure 2 Pyramid of adverse effects on health attributable to air pollution. 10 Figure 3 Estimated percent change and 95% confidence intervals in total mortality associated with a 10 ppb increase in the 1-hour maximum ozone levels and a 1-day lag with varying degrees of freedom per year for seasonality control. 51 Figure 4 Estimated percent change and 95% confidence intervals in cardiovascular mortality associated with a 10 ppb increase in the 1-hour maximum ozone levels and a 1-day lag with varying degrees of freedom per year for seasonality control. 52 Figure 5 Estimated percent change and 95% confidence intervals in respiratory mortality associated with a 10 ppb increase in the 1-hour maximum ozone levels and a 1-day lag with varying degrees of freedom per year for seasonality control. 53 Figure 6 Estimated percent change and 95% confidence intervals in cardiovascular hospital admissions associated with a 10 ppb increase in the 1-hour maximum ozone levels and a 1-day lag with varying degrees of freedom per year for seasonality control. 54 Figure 7 Estimated percent change and 95% confidence intervals in respiratory hospital admissions (all ages) associated with a 10 ppb increase in the 1- hour maximum ozone levels and a 1-day with varying degrees of freedom per year for seasonality control. 55 Figure 8 Pooled percent increase and the 95% confidence intervals for mortality outcomes for a 10 ppb increase in the 1-hour maximum ozone levels and a -day lag across the 12 Canadian cities with varying degrees of freedom per year for seasonality control. 56 Figure 9 Pooled percent increase and the 95% confidence intervals for hospital admissions for a 10 ppb increase in the 1-hour maximum ozone levels and a 1-day lag across the 12 Canadian cities with varying degrees of freedom per year for seasonality. 57 Figure 10 Estimated percent change and the 95% confidence intervals in total mortality associated with a 10 ppb increase in the 1-hour maximum ozone levels at various lag structures and degrees of freedom per year for seasonality control 59 Figure 11 Estimated percent change and the 95% confidence intervals in cardiovascular mortality associated with a 10 ppb increase in the 1-hour maximum ozone levels at various lag structures and degrees of freedom per year for seasonality control 60 Figure 12 Estimated percent change and the 95% confidence intervals in respiratory mortality associated with a 10 ppb increase in the 1-hour maximum ozone levels at various lag structures and degrees of freedom per year for seasonality control 61 VII Figure 13 Estimated percent change and the 95% confidence intervals in cardiovascular hospital admissions associated with a 10 ppb increase in the 1-hour maximum ozone levels at various lag structures and degrees of freedom per year for seasonality control 62 Figure 14 Estimated percent change and the 95% confidence intervals in respiratory hospital admissions associated with a 10 ppb increase in the 1-hour maximum ozone levels at various lag structures