Investigating the Impact of Extreme Heat on Human Health in Two Small Midwestern Communities

Urban residents are increasingly vulnerable to extreme heat, a risk which is
amplified by the urban heat island effect. Extreme heat is the leading cause of
weather-related fatalities in the U.S., with an estimated 1,300 deaths annually
— a number expected to rise due to climate change. While extensive research
has been conducted in large cities and metropolitan regions, smaller cities and
towns often face unique challenges that remain unexplored. This study aims
to address this gap by investigating the relationship between extreme heat and
emergency department (ED) visits in two small Midwest communities over an
eight-year period (2013-2021).

We analyze the impact of heat waves on community health using ED visits,
diagnosis data, and local climate data. We first identify all heat wave days in
each community over an eight-year period, with corresponding control days se-
lected for comparison. We use a generalized linear model (GLM) with negative
binomial distribution to calculate the relative risk ratio of ED visits during heat-
waves. Our analysis shows a statistically significant increase between 5%-10% in
ED visits for the two communities during heatwaves compared to control days,
highlighting the impact of extreme heat on local resources and health infrastruc-
ture. Aggregating the health data at the block group level and incorporating
local heat exposure data and socio-economic variables, we conduct a spatial
analysis to investigate whether high heat vulnerable areas are experiencing an
elevated rate of ED visits during heat waves.

We also investigate individual characteristics of residents needing ED ser-
vices. We observe notable differences in the relative risk (RR) of emergency
department (ED) visits during heatwaves across race, gender, and disease cate-
gories. Females in our study region were marginally more likely to visit the ED
compared to males (RR 1.06 vs RR 1.05) indicating potential gender-specific
vulnerabilities. Race also played a significant role in determining vulnerabil-
ity, as Non-White residents had a 20% higher likelihood of needing ED services
during heatwaves. We also observe statistically significant relationships be-
tween certain diseases and ED visits during heatwaves. Our analysis highlights
that individuals with cardiovascular, respiratory, and renal conditions were par-
ticularly vulnerable during extreme heat events. Specifically individuals with
respiratory illnesses had the highest risk of needing emergency services as their
risk increased by more than 50% during high heat days. These findings un-
derscore that individuals with pre-existing health conditions have an increased
vulnerability to extreme heat.

We conclude with a discussion about data limitations for heat-related health
data and highlight ways that communities can utilize a more robust dataset in
their climate resilience planning. One of the primary challenges encountered
in this study was the limited availability of diagnosis data. These challenges
highlight the need for more robust health data collection in small communities.
Despite these limitations, our research reveals significant patterns of vulnerabil-
ity and health impacts associated with extreme heat, highlighting the need for
tailored interventions and policies to address these issue