How Can We Better Protect Our Patients Against Extreme Heat?

June 23, 2025

Uncategorized 5 min read

By Claire Young

Peer Reviewed

Last summer, New Yorkers experienced a heat wave1—causing infrastructure failures2,3, poor air quality, and even deaths. Summers are only getting hotter4 and this is compounded with the “urban heat island effect”5. An average of 350 New Yorkers die prematurely every summer from heat-related injuries6. Those most at-risk for heat-related injury are adults over the age of 65, people with preexisting chronic disease (most notably cardiac or pulmonary disease) and very young children7. In the past 20 years there has been a 54% increase in heat-related mortality among geriatric patients8. Structural racism also plays a role; Black citizens are twice as likely as white New Yorkers to die from heat stress9. Age-adjusted death rates were highest in Brooklyn, and in neighborhoods with more residents living below federal poverty levels6.

How does heat affect the body? 

Physiologically, the human body has two mechanisms for responding to heat: vasodilation (redistributing blood flow towards the skin to transfer heat towards the external environment) and sweating (evaporative cooling)10. Thermal input from temperature-sensitive neurons in the anterior hypothalamus and non-thermal input such as dehydration trigger these pathways to maintain homeostasis11(p7). Genetic and disease status factors can affect an individual’s ability to limit core temperature elevation.

“Heat stress” injuries are directly due to exposure to heat, whereas “Heat-exacerbated” injuries occur when heat worsens existing chronic conditions. Hot temperatures are also associated with increased risk of infectious disease. Disease vectors such as mosquitos and ticks are migrating northward with rising summer temperatures12. Additionally, a Swiss team found a substantial increase in hospital admissions for infectious gastroenteritis during heatwaves13. A modeling study found that heat waves accelerated the spread of COVID-19 in the summer of 2022, arguing that social distancing efforts fail when people gather in air-conditioned public spaces14. 

Peripheral vasodilation increases cardiac demand while decreasing preload, causing the heart to pump faster and harder and increasing cardiac strain15. Patients with existing heart disease can develop mismatch between cardiac oxygen demand and delivery, leading to ischemia, infarction, and heart failure. A meta-analysis of temperature-related morbidity and mortality outcomes found that cardiovascular disease was the greatest cause of heat-related death among adults over 6516. Sweating is also associated with cardiovascular strain, as dehydration decreases blood volume (and preload) in addition to kidney injury7.

After heart failure, the second greatest cause of extreme heat mortality is lung damage due to hyperventilation17 and elevated air pollution during heat waves18.  Medications such as anticholinergics, antidepressants and opioids can also exacerbate heat sensitivity or reduce thermoregulatory capabilities7.

How can we prevent and address heat-related injuries to our patients?

Most New Yorkers who died of heat stress were exposed to dangerously high temperatures in their homes and did not have air conditioning6. A third of these people had an electric fan, suggesting this is not sufficient protection.

Fortunately, there are NYC-based programs that we can help our patients apply for to mitigate extreme heat:

  • Cooling Centers19

All New York Public Libraries are dedicated cooling centers, but the https://finder.nyc.gov/coolingcenters/ website lists all available centers and allows you to filter by handicap accessibility and pet friendliness.

  • Health Energy Assistance Program Cooling Assistance Benefit

Patients with monthly income below a set level, or who receive SNAP benefits or have a documented medical condition that is exacerbated by extreme heat may apply for a free air conditioner installation. https://otda.ny.gov/programs/heap/#cooling-assistance

  • Be a Buddy (BAB) Program

The BAB program connects patients at increased risk of heat injury with community volunteers in East Harlem, Hunts Point, and Brownsville for wellness checks. You can register patients for a buddy here: https://huntspoint.nyc/?page_id=1009

  • Register as a Life-sustaining equipment (LSE) customer with ConEdison

Patients who have at-home electric medical equipment (ie. Dialysis, respirators) can register as a LSE customer in the event of power outages to be contacted for emergency assistance: https://www.coned.com/-/media/files/coned/documents/accountandbilling/payment-plans-assistance/life-support-equipment-form.pdf.

  • Medication reconciliation and education

Finally, we can provide patients with education if their medications are associated with increased vulnerability to heat20 and consider alternatives if applicable. Common medications that can interact with heat include anticholinergics, antidepressants, antipsychotics, cardiac medications and CNS stimulants.

Claire Young is a Class of 2026 medical student at NYU Grossman School of Medicine

Peer Reviewed  by Michael Tanner, MD, Executive Editor, Clinical Correlations

Image courtesy of Robert Couse-Baker from Sacramento, California, CC BY 2.0 , via Wikimedia Commons

References

  1. Lewis J. New York City’s second heat wave of 2024 continues. Here’s the First Alert Forecast. CBS New York. July 8, 2024. https://www.cbsnews.com/newyork/news/heat-advisory-nyc-second-heat-wave-of-2024-forecast/ Accessed July 14, 2024.
  2. Stone B, Mallen E, Rajput M, et al. Compound Climate and Infrastructure Events: How Electrical Grid Failure Alters Heat Wave Risk. Environ Sci Technol. 2021;55(10):6957-6964. doi:10.1021/acs.est.1c00024
  3. Frost M. NYC’s infrastructure wasn’t built for the heat. Brooklyn Eagle. July 10, 2024. https://brooklyneagle.com/articles/2024/07/10/nycs-infrastructure-wasnt-built-for-the-heat/ Accessed July 14, 2024.
  4. Kasakove S, Rojas R. U.S. Heat Wave: Heat Records Fall Across a Sweltering Nation. The New York Times. https://www.nytimes.com/live/2022/05/21/us/weather-east-coast-heat. May 21, 2022. Accessed July 14, 2024.
  5. NYC Hazard Mitigation Plan. Extreme Heat. https://nychazardmitigation.com/documentation/hazard-profiles/extreme-heat/ Accessed July 14, 2024.
  6. City of New York. 2024 heat mortality annual report in NYC | Environment and Health Data Portal. Environment & Health Data Portal. https://a816-dohbesp.nyc.gov/IndicatorPublic/data-features/heat-report/ Accessed July 13, 2024.
  7. Ebi KL, Capon A, Berry P, et al. Hot weather and heat extremes: health risks. Lancet. 2021;398(10301):698-708. doi:10.1016/S0140-6736(21)01208-3
  8. Sorensen Cecilia, Hess Jeremy. Treatment and Prevention of Heat-Related Illness. N Engl J Med. 2022;387(15):1404-1413. doi:10.1056/NEJMcp2210623
  9. New York City Department of Health and Mental Hygiene. Heat-related Deaths in New York City, 2013. Epi Data Tables. August 2014. https://www.nyc.gov/assets/doh/downloads/pdf/epi/datatable47.pdf Accessed July 13, 2024.
  10. Kenny GP, Jay O. Thermometry, Calorimetry, and Mean Body Temperature during Heat Stress. In: Comprehensive Physiology. John Wiley & Sons, Ltd; 2013:1689-1719. doi:10.1002/cphy.c130011 Accessed July 13, 2024.
  11. Fealey RD. Interoception and autonomic nervous system reflexes thermoregulation. Chapter 7 . In: Buijs RM, Swaab DF, eds. Handbook of Clinical Neurology. Vol 117. Autonomic Nervous System. Elsevier; 2013:79-88. doi:10.1016/B978-0-444-53491-0.00007-9
  12. Rossati A. Global Warming and Its Health Impact. Int J Occup Environ Med. 2017;8(1):7-20. doi:10.15171/ijoem.2017.963
  13. Manser CN, Paul M, Rogler G, Held L, Frei T. Heat waves, incidence of infectious gastroenteritis, and relapse rates of inflammatory bowel disease: a retrospective controlled observational study. Am J Gastroenterol. 2013;108(9):1480-1485. doi:10.1038/ajg.2013.186
  14. Lian X, Huang J, Li H, et al. Heat waves accelerate the spread of infectious diseases. Environ Res. 2023;231(Pt 2):116090. doi:10.1016/j.envres.2023.116090
  15. Crandall CG, González-Alonso J. Cardiovascular function in the heat-stressed human. Acta Physiol. 2010;199(4):407-423. doi:10.1111/j.1748-1716.2010.02119.x
  16. Bunker A, Wildenhain J, Vandenbergh A, et al. Effects of Air Temperature on Climate-Sensitive Mortality and Morbidity Outcomes in the Elderly; a Systematic Review and Meta-analysis of Epidemiological Evidence. EBioMedicine. 2016;6:258-268. doi:10.1016/j.ebiom.2016.02.034
  17. White M. Components and mechanisms of thermal hyperpnea | Journal of Applied Physiology. A Physiological Systems Approach to Human and Mammalian Thermoregulation. August 1, 2006. Accessed July 14, 2024. https://journals.physiology.org/doi/full/10.1152/japplphysiol.00210.2006
  18. Hansel NN, McCormack MC, Kim V. The Effects of Air Pollution and Temperature on COPD. COPD J Chronic Obstr Pulm Dis. 2016;13(3):372-379. doi:10.3109/15412555.2015.1089846
  19. Widerynski S. Use of cooling centers to prevent heat-related illness : summary of evidence and strategies for implementation. 2017. https://stacks.cdc.gov/view/cdc/47657 Accessed July 13, 2024.
  20. Pathak N. Common medications may increase the dangers of heat waves » Yale Climate Connections. Yale Climate Connections. July 26, 2022. http://yaleclimateconnections.org/2022/07/common-medications-may-increase-the-dangers-of-heat-waves/ Accessed July 14, 2024.

 

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