Modeling the relationships between historical redlining, urban heat, and heat-related emergency department visits: An examination of 11 Texas cities

Abstract

Place-based structural inequalities can have critical implications for the health of vulnerable populations. Historical urban policies, such as redlining, have contributed to current inequalities in exposure to intra-urban heat. However, it is unknown whether these spatial inequalities are associated with disparities in heat-related health outcomes. The aim of this study is to determine the relationships between historical redlining, intra-urban heat conditions, and heat-related emergency department visits using data from 11 Texas cities. At the zip code level, the proportion of historical redlining was determined, and heat exposure was measured using daytime and nighttime land surface temperature (LST). Heat-related inpatient and outpatient rates were calculated based on emergency department visit data that included ten categories of heat-related diseases between 2016 and 2019. Regression or spatial error/lag models revealed significant associations between higher proportions of redlined areas in the neighborhood and higher LST (Coef. = 0.0122, 95% CI = 0.0039–0.0205). After adjusting for indicators of social vulnerability, neighborhoods with higher proportions of redlining showed significantly elevated heat-related outpatient visit rate (Coef. = 0.0036, 95% CI = 0.0007–0.0066) and inpatient admission rate (Coef. = 0.0018, 95% CI = 0.0001–0.0035). These results highlight the role of historical discriminatory policies on the disparities of heat-related illness and suggest a need for equity-based urban heat planning and management strategies.

Residential and Race/Ethnicity Disparities in Heat Vulnerability in the United States

“…The analyses in this study each supported the hypothesis that vulnerability to heat-related adverse health outcomes is greatest in historically defined and contemporaneously defined disadvantaged communities and in communities of color in the United States. Historically "redlined" census tracts were associated with higher heat vulnerability, consistent with similar analyses that found higher LST and lower green space in these segregated areas (Hoffman et al, 2020;Li et al, 2021;Namin et al, 2020;Nardone et al, 2021;Schinasi et al, 2022;Wilson, 2020). This association was evidenced by the correlation and regression analyses between continuous, weighted HOLC score and HVI score, as well as significantly increasing HVI scores between incrementally higher-risk HOLC grades.…”

“…Finally, we observed high mean HVI scores among non‐White race/ethnicity groups, and overrepresentation of people of color in the most vulnerable census tracts. Together, these results demonstrate place‐ and race/ethnicity‐based disparities in heat vulnerability across the United States, and add to the literature on the long‐term adverse environmental and health implications associated with racist housing policies (Hoffman et al., 2020 ; Li et al., 2021 ; Namin et al., 2020 ; Nardone et al., 2021 ; Schinasi et al., 2022 ; Wilson, 2020 ).…”

“…Together, these results demonstrate place-and race/ethnicity-based disparities in heat vulnerability across the United States, and add to the literature on the long-term adverse environmental and health implications associated with racist housing policies (Hoffman et al, 2020;Li et al, 2021;Namin et al, 2020;Nardone et al, 2021;Schinasi et al, 2022;Wilson, 2020).…”

“…Beyond the improvements to the HVI, this study provided a unique analysis of the place‐ and race/ethnicity‐based disparities associated with heat vulnerability. Previous studies have measured higher LST and lower green space in “redlined” areas (Hoffman et al., 2020 ; Li et al., 2021 ; Namin et al., 2020 ; Nardone et al., 2021 ; Schinasi et al., 2022 ; Wilson, 2020 ), but these studies failed to capture the various other socioeconomic, demographic, or biological determinants of vulnerability (World Health Organization, 2021 ). Additionally, this study is the first to quantify heat vulnerability across the various race/ethnicity groups in the United States, further illustrating the vulnerability of communities of color.…”

“…The disproportionate exposure of communities of color in the United States to environmental hazards, often ascribed at least in part to racially driven residential segregation policies, is a fundamental manifestation of environmental racism (Bravo et al., 2016 ; Chavis, 1994 ; Gee & Payne‐Sturges, 2004 ; Lopez, 2002 ; Morello‐Frosch & Jesdale, 2006 ; Perry, 2007 ). Recently, heat‐related outpatient emergency department visits and inpatient admissions from the emergency department were found to be higher in “redlined” neighborhoods, evidence of the potential adverse health consequences at the intersection of racist policies and climate change (Li et al., 2021 ).…”