How extreme heat affects America's most vulnerable

Last August, residents of New Orleans endured a spate of extreme heat alerts, warning of successive days with temperatures in the triple digits and little relief after sundown.

The city's heat problem is both chronic and multifaceted, says Julia Kumari Drapkin, founder and CEO of ISeeChange, an online platform for climate data and weather tracking.

"Many [homes] have been storm-battered, and our low- to moderate-income homeowners are really having a hard time maintaining their homes with such extreme costs and stresses," she says. "One out of every three people in the South cannot afford their utility bills."

Many of the New Orleanians who logged their experiences on ISeeChange last summer wrote of high energy bills and inside temperatures as high as 89 degrees Fahrenheit, even with the air conditioner running nonstop. Some residents report seeing their energy bills double or even triple during the summer months.

In the summer of 2023, Jaime Madrigano, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, partnered with ISeeChange on a five-year project funded by the National Institutes of Health designed to estimate the health burden of heat in New Orleans. It aims to identify individual and neighborhood characteristics, as well as behavior patterns, that increase vulnerability to heat, particularly for people who can't afford to adequately cool their homes.

"The home environment can actually be a substantial risk in and of itself," says Madrigano, an associate professor in Environmental Health and Engineering, who researches environmental and climate-related stressors with the goal of informing equitable health policies. "We know that people are often dying right in their homes. If you're financially constrained or on a fixed income, you're that much more subject to these kinds of weather and climate stressors."

Madrigano and her research team combined information gathered over two weeks from temperature and humidity sensors in the bedrooms of 70 mostly Black residents of the city's Upper Ninth Ward. In summer 2024, they collected data from residents of the Hollygrove and Hollygrove-Dixon neighborhoods. Additional data from the Louisiana Department of Health will help to provide a picture of the most affected communities, based on heat-related hospitalizations, and the greatest contributing factors to those hospitalizations.

A preliminary analysis of the Upper Ninth Ward data showed that indoor temperatures averaged 80 degrees Fahrenheit but approached 90 degrees at certain times in a quarter of the homes sampled, because either air conditioning units couldn't keep up or residents, worried about electric bills, didn't run the units enough to keep their homes at safe temperatures. The granular data gathered over a two-week period will supplement climate and satellite data.

The consequences of extreme heat go well beyond financial stress and physical discomfort. Extreme heat is the deadliest of all weather-related events and is associated with mental health issues, heat strokes, dehydration, and myriad cardiovascular, kidney, and respiratory disorders. Societal impacts include increased violence, declines in worker productivity, and poor school performance.

Extreme heat poses an unequal burden for certain racial and income groups, according to a 2021 study published in Nature. People of color and those living below the poverty line are more likely to live in urban heat islands, like much of New Orleans' Upper Ninth Ward. There, impervious surfaces, pollution, traffic, and sparse greenery can increase temperatures by at least 8 degrees Fahrenheit compared to greener, less developed areas.

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In January 2024, the work of ISeeChange and other advocates contributed to the city's introduction of the Healthy Homes ordinance, which requires rental property owners to provide cooling systems capable of maintaining a maximum bedroom temperature of 80 degrees Fahrenheit to three feet above the floor. Madrigano hopes that the results of her study will prove useful to policymakers looking to update this ordinance or consider other adaptive measures to protect the public's health during extreme heat events.

"Residents who can't afford to stay cool at home are left with few options to protect themselves from dangerous temperatures," Madrigano says. "That's why it's so important to ensure people can stay safe at home. During an extreme heat event, it can be a matter of life and death."

A version of this article originally appeared in Hopkins Bloomberg Public Health magazine.