Heat-Related Mortality in a Warming World: Implications and Ways Forward
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Heat-Related Mortality in a Warming World: Implications and Ways Forward By Caroline Blanck A Senior Honors Thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Science with Honors in Environmental Science at Brown University Thesis Advisor: Gregory Wellenius Collaborator: Kate Weinberger Second Reader: J. Timmons Roberts April 2019 Abstract Background: Heat has been, and will continue to be, a major environmental hazard, public health concern, and local and national economic and security challenge. Extreme high temperatures lasting multiple consecutive days (heat waves) and high ambient temperatures may cause heat-related mortality. However, it is not well known how the risk of heat-related health effects varies by age, gender, or race. Objectives: This thesis examines the influences of age, gender, and race on a person’s risk of heat-related mortality, using data from the Brown University School of Public Health and the National Center for Health Statistics. Methods: The time period for this study is identified as 1987 to 2006. Using data from the National Center for Health Statistics, we acquired individual-level data on all deaths (excluding those from external causes) in counties in the contiguous United States with a population greater than 100,000 residents. We chose to focus on the twenty counties with the greatest number of deaths. This study analyzed deaths due to heat, aggregated by age, gender, and race. Results: The results from this thesis indicate that, although the demographic groups with the highest relative risk for heat-related mortality varied by county, overall the elderly, females, and Black people are at increased risk of heat-related mortality. Furthermore, populations in cooler climates will be more greatly affected by heat-related mortality than those in warmer climates. Conclusions: The effects of heat-related mortality in the United States are localized, and thus highlight the need for local policies and initiatives that aim to diminish heat-related mortality. 1 Acknowledgements To my mother, Wendy, my father, Peter, and my siblings, Jason, Daniel, Albert, Elise and Harry, words cannot begin to express the appreciation and gratitude I feel for your ceaseless love, support, encouragement, and unsolicited advice. Thank you for instilling in me a love of learning and a drive to repair the world. I love you. I would like to express deepest thanks to Gregory Wellenius, my thesis advisor, Kate Weinberger, my collaborator, and Timmons Roberts, my academic advisor, along with the countless other faculty I have encountered at Brown University. It was under your tutelage and guidance which I discovered my passion. Your mentorship and intuition have been invaluable. To the people who have shaped my experience at Brown University, the friends who have become family, I thank you. I have learned from you everyday over the past four years and it is because of each of you that this thesis is complete. Without your inspiration and insight, friendship and fortitude, this thesis would just be a collection of words and this university just a piece of land. 2 Table of Contents Introduction 4 PART ONE: LITERATURE REVIEW 7 Climate change and heat 8 Heat-related morbidity and mortality 8 Heat-related mortality over time 10 Urban Heat Island Effect 11 Determinants of Heat-Related Mortality Vulnerability 13 Heat-related mortality and age 14 Heat-related mortality and gender 17 Heat-related mortality and race 20 Heat-related mortality and access to air-conditioning 22 Economic Costs of Heat-Related Mortality 23 PART TWO: QUANTITATIVE ANALYSIS 26 Introduction 27 Methods 28 Results 31 Heat-related mortality overall 33 Heat-related mortality and age 38 Heat-related mortality and gender 42 Heat-related mortality and race 47 Discussion 52 Heat-related mortality and age 53 Heat-related mortality and gender 54 Heat-related mortality and race 54 Socioeconomic conditions 55 Limitations 56 PART THREE: POLICY IMPLICATIONS 57 United States Climate Projections 58 United States Demographic Projections 59 Heat-related Mortality Projections 60 Mitigation and Adaptation Measures 62 Heat response plans (HRPs) 63 Case Study: Milwaukee, Wisconsin 66 Case Study: Maricopa County, Arizona 67 Vulnerability Mapping 69 Case Study: New York State 71 Case Study: Philadelphia, PA 72 Stakeholder Participation 73 Communication and Social Marketing 74 Case Study: Chicago, IL 75 Reducing the Urban Heat Island Effect 77 Efficient air conditioning 78 Conclusion 80 References 82 Appendix 89 3 Introduction Heat and hot weather is a crucial determinant of human health and mortality. Heat is a grave peril for the human health and society, which can lead to morbidity, mortality and economic damages. Thousands of excess deaths occur annually resulting from heat stroke and the aggravation of chronic respiratory and cardiovascular conditions (Kovats & Hajat, 2008; Basu & Samet, 2002). Estimates suggest that, on average, there were approximately 618 deaths directly attributed to heat each year in the United States between 1999 and 2010 (CDC, 2012), killing more people, on average, than any other extreme weather event (Office of Climate, Water, and Weather Services, 2013; Berko et al., 2014). Not only is heat detrimental to health, but also to the economy. According to the Fourth National Climate Assessment produced by the United States Global Change Research Program (USGCRP), annual damages associated with heat-related deaths may cost the United States economy up to $140 billion in 2090 under current climate projections (Ebi et al., 2018). Thus, due to the health and economic effects of extreme heat, it is crucial that this issue is studied to create efficient and equitable solutions that will save the most lives, and in turn the most money and equity, possible. There is much consensus on the effects of heat on environmental systems, such as flora, fauna, ecological and hydraulic systems, and on the human body (IPCC, 2007), yet there is little consensus on what exactly constitutes heat. Hot is a relative term depending on geographic location and heat waves vary in intensity and duration (Kilbourne, 1997). Consequently, there is difficulty in estimating the actual number of heat-related deaths annually. Currently, there is a 4 lack of a standardized criteria for attributing death due to heat and death from other causes that may have been exacerbated by heat, such as cardiovascular disease or respiratory disease, which often are not included in estimations (Berko et al., 2014). Heat has been, and will continue to be, a major environmental hazard, public health concern, and local and national economic and security challenge. Extreme high temperatures lasting multiple consecutive days (heat waves) and high ambient temperatures may cause heat-related mortality. While human populations may acclimate to their local climate conditions, in physiological, behavioral, and cultural manners, there are still absolute limits of heat exposure that humans may withstand. Humans may adapt to changing climates and environments using air-conditioning. However, the amount of heat an individual may be able to tolerate and withstand may vary with physical and socioeconomic factors (Kovats & Hajat, 2008). While heat waves and high temperatures may not be preventable unless actions to mitigate climate change are taken, heat-related mortality may be preventable depending on public health measures taken (Kilbourne et al., 1982). To best prevent heat-related mortality, the public health and environmentalist communities must understand who is most vulnerable to heat and how compounding factors work to increase or decrease these vulnerabilities (Clarke, 1972; Ellis, 1972; Schuman, 1966; Jones et al., 1982; Martinez et al., 1989; Rogot et al., 1992). Heat has vastly different consequences for different demographics within the United States. Elderly populations, women, and racial/ethnic minorities may have heightened vulnerability not only to the health effects of heat (CDC, 2012), but also to its economic impacts (Schmeltz et al., 2016). To equitably and effectively adapt to the increased frequency and 5 severity of heat due to climate change, it is imperative that different the impacts of heat on different populations are acknowledged, studied, and understood. This thesis examines the influences of age, gender, and race on a person’s risk of heat-related mortality, using data from the Brown University School of Public Health and the National Center for Health Statistics. It focuses on the twenty counties across the United States with the highest absolute number of deaths due to all-cause mortality, which include Los Angeles County, CA, Cook County, IL, Wayne County, MI, Kings County, NY, Maricopa County, AZ, San Diego County, CA, Harris County, TX, Philadelphia County, PA, Queens County, NY, Orange County, CA, Allegheny County, PA, Cuyahoga County, OH, Broward County, FL, New York County, NY, Dallas County, TX, Pinellas County, FL, Palm Beach County, FL, Middlesex County, MA, Nassau County, NY and Bronx County, NY, and investigates the differing levels of heat-related mortality among the aforementioned groups within those sites. This study reviews twenty years of continuous data. It is unique in that it is among the only studies of its size that analyzes heat-related mortality broken down by age, gender, and race over a continuous twenty year period. As global temperatures rise, the impacts of heat-related mortality may become more profound and widespread. This study aims to shed light on factors that increase an individual’s vulnerability for heat related mortality. It then offers policy recommendations to help address these vulnerabilities. It is crucial that the knowledge generated in this thesis is used to further resilience to climate change induced heat. 6 PART ONE: LITERATURE REVIEW 7 Climate change and heat There is unequivocal evidence that the Earth’s global average temperatures are warming. Climate change poses myriad threats to the natural environment and humans. It significantly impacts the environment, which in turn affects human health, human and societal development, and human prosperity.