This blog is authored by Elizabeth Matsui — director of the Center for Health and Environment: Education and Research at Dell Medical School — and Geeta Persad, an assistant professor in the Jackson School of Geosciences and a member of CHEER’s steering committee.
As part of an ongoing series, CHEER discusses a “hot topic” in environmental health and its impact on health and research.
As we head into fall, a brutally hot summer is thankfully receding. All sorts of heat records were broken here in Central Texas, including a record stretch of 45 days straight with high temperatures over 100F. Austin Public Health documented more than 1100 heat-related illness emergency department visits by the end of August, including some heat-related deaths.
How Heat Impacts Health
These statistics just scratch the surface of the full impact of heat exposure on health. Heat also has indirect health effects, the magnitude of which are poorly understood. Heat can directly harm health by causing dehydration, cramping, heat exhaustion and life-threatening heat stroke. It is also linked to chronic disease, morbidity and mortality, and adverse pregnancy and birth outcomes. Cardiovascular disease, kidney disease and respiratory diseases, including asthma and chronic obstructive pulmonary disease, are exacerbated by extreme heat exposure. There is also emerging data linking extreme heat to adverse mental health outcomes and upticks in violence.
The population health burden of extreme heat is thus difficult to estimate but likely substantial. With climate projections pointing to increasing temperatures and heat waves, the burden is expected to grow. The health burden, however, is not distributed uniformly.
Some groups are more likely to be exposed to extreme heat and have risk factors that increase the likelihood of heat-related adverse health effects. Historically marginalized groups, such as people of color and those living in poverty, are more likely to work in outdoor settings and less likely to be protected from exposure either at work or in their homes. People who are unhoused are also more likely to be exposed and lack access to cool indoor spaces. These same populations are also more likely to have chronic health conditions that make them more susceptible to adverse health effects of heat. Despite this, we have a poor understanding of the contribution of these inequities to health disparities.
Efficacy of Heat Interventions
Cities have been working to adapt to the already increased extreme heat by implementing urban planning interventions with the goal of reducing ambient local temperatures or reducing peoples’ exposure to those temperatures. Examples of such interventions include planting trees to provide shade, applying reflective coatings on streets, sidewalks, and roofs, or opening cooling centers during heat events.
Action is laudable, but many questions remain about such efforts. For example, do interventions actually reduce ambient temperatures? Some data suggests that people may feel hotter walking on sidewalks/near roads with the reflective coating because the heat is reflected away from the ground back into the ambient air. Other interventions, such as tree cover, do lower temperature, but the impact of such interventions on health and health equity is poorly understood.
Interventions targeted at reducing exposure must further grapple with how people will interact with the intervention. For example, many target populations do not use cooling centers even during extreme heat, and the reasons remain largely understudied and unaddressed.
Research on Heat & Health
All of this underscores the urgency for research on heat and health, and the CHEER community is strongly positioned to be at the forefront of this work. Fortunately, there have been funding opportunities to support such work, including from the Burroughs Wellcome Fund and the National Institutes of Health. CHEER members are competing for these funds, and we see a groundswell of climate change and health research at UT on the horizon.