Introduction
Climate change has increased concern over warm season temperatures due
to the health effects of extreme temperature exposures (1). In the
United States, a small body of literature documents disparities in
summertime temperatures experienced by ethnoracially minoritized
subgroups (2, 3). This is a concern for several reasons. Minoritized
subgroups have increased temperature vulnerability (4, 5), which may be
due to higher levels of comorbidities (6–8). Further, air temperature
estimates may systematically underestimate true exposures for vulnerable
populations (9, 10), so the effects of these exposures also may be
underestimated. In addition, minoritized populations experience higher
energy burden and energy insecurity (11, 12). Given that air
conditioning is the dominant individual-level adaptive strategy to heat
in the U.S., minoritized populations may have reduced adaptive capacity
to climate change (13, 14). Thus extreme temperature exposures represent
a form of underestimated structural racism in climate impacts.
Social disadvantage and temperature exposure are related. Spatial
temperature profiles are correlated with socioeconomic status, and land
use/cover associated with the urban heat island effect is more prevalent
in poor communities and communities of color (3, 15). More recently,
Hoffman et al. identified an association between the Home Owners’ Loan
Corporation historical housing practices, often referred to as
“redlining”, and higher summertime land surface temperatures within
cities (2). This work is bolstered by evidence that places benefiting
from these lending practices now have attributes associated with lower
summertime temperatures, such as increased vegetation and less
impervious surfaces (16, 17). However, populations and developed land
area have grown substantially since the 1940s. Thus while previous
studies are integral to understand the formation of environmental
inequities, present-day interventions would benefit from analyses
associating current measures of segregation with air temperature.
Further, many previous studies have used land surface temperatures, but
near-surface air temperatures measured at ground-based monitors are more
relevant for human thermoregulatory capacity and energy policy.
In the U.S., there is growing recognition of energy burden and energy
insecurity (18, 19), yet few policies that explicitly protect
disadvantaged groups that experience these hardships (20). The
Low-Income Home Energy Assistance Program (LIHEAP) is one such
protection program, but it largely distributes funding based on cold
season energy demand and provides less support for the warm season (21).
Indirect measures of energy demand are used to calculate LIHEAP funding
allocations, specifically heating and cooling degree days. Although
allocations assume that everyone in a state or region is exposed to
roughly equal temperatures, residential segregation and temperature both
vary over fine spatial scales. Thus air temperature disparities may mean
that minoritized groups are exposed to systematically higher summer
temperatures. Here we used a fine spatial resolution air temperature
product to assess the potential relationship between area-level
ethnoracial composition and warm season air temperatures. We asked:Do minoritized groups experience hotter summers than the area
average, and do non-Hispanic white people experience cooler summers? We
then tested whether present-day measures of segregation are associated
with summertime temperatures, exploring a likely pathway between
exposure and temperature vulnerability.