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A Harvard and Boston University study found roughly 1 in 10 emergency department visits across 19 states were heat-driven during two severe heat waves last summer, using near real-time health data to enable faster hospital staffing decisions.

What is a key fact in this story? (1)

**Harvard and Boston University researchers** published a study in Nature Health analyzing more than 8 million emergency department visits over three summers (2023–2025), finding that approximately 1 in 10 ED visits across 19 states were driven by heat during two severe heat waves last summer.

What is a key fact in this story? (2)

**Heat-related visits** were especially pronounced for psychiatric and kidney-related emergencies, and affected all-cause visits more broadly, according to the study, which used Truveta's near real-time de-identified electronic health records just two weeks after the heat waves hit.

Study: 1 in 10 ER Visits Heat-Driven in 2025 Waves — SkimNews

By Inside Climate News · Summarized & edited by Kapil Samant · 2026-09-04

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Harvard and Boston University researchers published a study in Nature Health analyzing more than 8 million emergency department visits over three summers (2023–2025), finding that approximately 1 in 10 ED visits across 19 states were driven by heat during two severe heat waves last summer.
Heat-related visits were especially pronounced for psychiatric and kidney-related emergencies, and affected all-cause visits more broadly, according to the study, which used Truveta's near real-time de-identified electronic health records just two weeks after the heat waves hit.
Dr. Robert Brewer, associate director of emergency medicine at St. Peter's Hospital in Albany, said heat waves bring more dehydration, kidney problems, heart strain from vasodilation, and psychiatric crises, noting that a ~10% volume surge lets him staff appropriately when warned in advance.
Lead author Amruta Nori-Sarma (Harvard) said near real-time data could help hospitals allocate beds more efficiently as climate change brings longer, more intense, and more frequent heat waves to regions like the Northeast unaccustomed to them.
Dr. Abel Kho (Northwestern), whose own Chicago ED heat findings align with the study, called its 19-state geography a major strength but flagged limitations including reduced transparency from using a commercial dataset, state-level rather than urban-granular data, and self-selected health systems that may exclude uninsured and unhoused patients.
Cook County, Illinois recorded 13 heat deaths this summer — more than double the previous decade's high — most concentrated on the historically disenfranchised South and West sides of Chicago, per the Chicago Sun-Times.

Why it matters: For emergency departments and health systems, the study demonstrates that near real-time heat surveillance could shift reactive scrambling into proactive staffing — the lead author says hospitals could prepare for a roughly 10% volume surge during heat waves. The 19-state scale and its alignment with independent Chicago findings give hospital administrators a replicable model as heat seasons grow longer and hotter, while the Truveta dataset's blind spots (uninsured, unhoused, urban granularity) leave the most heat-vulnerable populations undercounted.