Tree Canopy and Temperature: Health Outcomes among Dually Enrolled Seniors

• In Event: Climate Inequities: Health, Migration, and Infrastructure in the Face of Disasters

Abstract

Urbanization and climate change have led to rising temperatures in cities, posing significant health risks for overburdened populations, such as seniors. Urban tree canopy coverage serves as a mitigation strategy to reduce the negative health impacts of extreme heat exposure and air pollution, by providing shade and cooling, and absorbing greenhouse gases, such as carbon dioxide. Studies link higher tree canopy coverage to improved physical and mental health outcomes, including lower mortality and fewer emergency department visits. However, it remains unclear whether these benefits extend to dually enrolled Medicare and Medicaid beneficiaries—a population with higher rates of chronic illness and social vulnerability, and thus greater susceptibility to environmental stressors like heat and pollution. Our study aims to make three significant contributions to environmental policy. First, our study will expand the geographical scope of tree canopy research by including a larger number of cities. Most existing studies focus on a limited number of locations, leaving a gap in our understanding of regional differences. Second, our study is the first of its kind to introduce another disparity in the distribution of tree canopy coverage. Lastly, it examines understudied health outcomes in this context, including prescription fills for mental health conditions and ED visits related to behavioral health issues, providing new insights into how environmental factors affect vulnerable populations. We utilize multivariate regression models to quantify the relationships between tree canopy coverage, extreme temperatures, and key health outcomes. Interaction terms are included to examine whether the protective effects of tree canopies against extreme temperatures vary by neighborhood-level rates of dual enrollment. We link tree canopy data from the Annual Land Cover Database (NLCD) Tree Canopy Coverage dataset with Medicare data for 2019-2020, enabling a nationwide analysis of mental health outcomes in relation to environmental exposures. To enhance validity, we incorporate data from NASA’s Global Ecosystem Dynamics Investigation (GEDI), which provides precise measurements of tree canopy height. The NLCD dataset is valuable due to its ability to provide annual tree canopy estimates at a broad geographic scale, making it well-suited for national-level analysis. Our preliminary findings reveal variation in tree canopy coverage across cities. For example, Atlanta has the highest tree canopy coverage at 32.7%, in comparison to Chicago and Indianapolis at 10.7% and 12.7% respectively. Furthermore, we observe an inverse relationship between tree canopy coverage and the proportion of dually enrolled Medicare-Medicaid recipients, suggesting that these low-income, medically vulnerable populations may have less access to green infrastructure — increasing their exposure to the negative health impacts of extreme heat. We conclude with a series of policy recommendations at the local level to address the disproportionate impacts of extreme heat exposure on dual enrolled patients. Our recommendations focus primarily on climate change mitigation and senior’s health and wellbeing.  

Author

• Dennis Vera, Indiana University
  Presenting Author