Calculating the damage from a hurricane or wildfire is straightforward: simply add up the cost of destroyed buildings, disrupted business and livelihoods lost.
For extreme heat — the kind that has gripped Florida and much of the nation for months now — the toll is harder to tally, because the real danger of heat isn’t to homes and power lines, it’s to human health. And, experts say, the official numbers likely don’t capture the whole picture.
RELATED: Mishmash of how heat deaths are counted complicates efforts to keep people safe
This summer’s record-breaking, unrelenting heat has already claimed at least one life, according to friends and advocates of a 29-year-old farm worker who collapsed on a Homestead fruit farm in July. Fire rescue in Miami-Dade also has noticed an uptick in 911 calls for heat exhaustion and heat stroke compared to last summer, which was less hot. June through mid-July of last year, the department received 86 calls. This year, they got 99.
But more complete official records, including a daily count of heat hospitalizations and deaths in South Florida, are harder to come by. Local hospitals declined to provide to the Miami Herald their own count of heat hospitalizations and deaths. The state does track it for some counties, including Miami-Dade, but the Department of Health did not immediately respond to a request for data.
However, several doctors at hospitals around the county say they haven’t seen more patients struggling with the heat, despite a near-daily drumbeat of high-temperature records being shattered.
“I haven’t heard about a whole lot more deaths,” said Dr. Cheryl Holder, interim executive director of Florida Clinicians for Climate Action. “This is a good thing.”
Heat is hard to measure
But many experts, including Holder, believe heat-related illnesses and deaths are almost certainly undercounted in Florida and nationwide. One major reason is the way the medical industry keeps records.
Heat affects the body in a number of ways, including some that scientists are still discovering. Besides the obvious direct links, like heat stress and heat stroke, high temperatures can worsen heart and lung conditions, chronic illnesses like Lupus, diabetes and asthma.
But when someone is hospitalized for one of the conditions that are worsened by heat, their provider typically records only the chronic illness, not heat.
“What you end up with is a correlation that never proves causality, or you end up with not the strongest numbers,” said Holder. “And it seems like it is not an important number because it’s low.”
Perhaps the best example of how yawning the gap is between the official number of illnesses and deaths reported and what researchers project as a more likely impact can be found in a health report Miami-Dade commissioned last year. Miami-Dade’s medical examiner’s office has officially recorded only two deaths directly linked to heat in the last five years. But researchers reviewed all excess deaths in the county during that time and concluded the real annual average could be much higher: 34 deaths — every year.
Long-term trends of hospitalizations, emergency room visits and even deaths due to heat have varied wildly in Florida in recent years, with no clear trend upward or down through at least 2021, the most recent year data is publicly available. They’re also heavily affected by storms. After hurricanes, when power is out and people are stuck in the heat, hospitalizations and deaths tend to rise.
Miami-Dade’s heat vulnerability study found an average of 58 hospitalizations and 301 emergency department visits a year for heat-related illnesses specifically. But that kind of information is not reported by every county, making it even harder to calculate the impact heat has on Floridians’ health.
But even by the state’s measure, there’s a connection between high temps and more sick residents.
A 2015 report from Florida’s Department of Health found that as the temperature and heat index rose, more people visited the emergency room for heat-related illnesses like heat stress and heat stroke.
“As both measures of exposure increased, rates of heat-related illness increased significantly,” the state report said.
And nationally, heat-related deaths have been increasing since 1990, according to Centers for Disease Control data reported by the Guardian. Average annual heat-related deaths rose 95% from 2010 to 2022, the newspaper reported.
Another complicating factor for Florida: Unlike other places, which usually experience extreme heat in the form of a clearly defined heat wave, the Sunshine State is hot year-round.
“We are always hot, to a certain degree. So how much is acclimatization going to confound the data?” asked Holder. “No one has ever really studied chronic heat exposure. When it comes to heat like that, you don’t have a sizable data set in the past.”
And unlike other places, Florida has been hot for a while. So most people have homes, cars and even workplaces with air conditioning and have easy ways to stay safe when it gets unbearable outside.
These preexisting protections, and the fact that human bodies can — and do — acclimate to the heat, is why some doctors think hospitalization and deaths are relatively low, despite record heat.
“We don’t tend to see as much as one might think,” said Dr. Hany Atallah, chief medical officer at Jackson Memorial Hospital. “Our population here, they know fairly well what to do.”
Counting Deaths
Tallying the worst case of extreme heat — death — is just as difficult, if not more so, experts say.
Chris Uejio, an associate professor at Florida State University and lead author of Miami-Dade’s heat vulnerability study, said a coroner can only classify a death as heat-related if the core body temperature of the deceased person is elevated. That rules out bodies discovered a while after death.
Classifying heat deaths also runs into the same problem as classifying heat-related illnesses: if someone dies of a disease or condition exacerbated by heat, the disease is what’s listed on the death certificate.
That’s why Uejio and other heat action advocates in Miami-Dade partnered with Baptist Hospital to hold training sessions for local clinicians to explain the connections between heat and health issues, as well as train them to better record heat-related illnesses and deaths.
“I think it’s underappreciated to some extent how widespread and common heat is as a public health problem,” Uejio said. “We know this is going to be a continual threat and a bigger one going forward.”
Uejio was the researcher behind Miami-Dade’s new annual average heat deaths estimate — 34. He used a statistical analysis that took into account all deaths in the last five years and came up with a much higher number that he said better reflects the real toll of extreme heat in Miami-Dade.
To illustrate how heat deaths get undercounted, consider the case of Efraín López García, a 29-year-old farmworker who collapsed and died while working on a farm in Homestead on July 6, when the heat index hit 106 degrees.
López García’s death was quickly and widely reported — but only because of the efforts of the Florida Farmworker Association. A day after López García’s death, an association staffer saw a post about it on Facebook. Another staff member, Claudia Gonzalez, searched through the association’s member rolls to find people with matching last names and cold-called them until she found López García’s cousin, who told her his brother had been with López García when he died.
“The same day that we found out about [López García’s] death, we found his family and we made a report to OSHA,” Gonzalez said. “It’s about knowing the community. All of that would have been impossible if the community didn’t come to us.”
Had the association not investigated, the story may not have been widely known. “These are deaths that we don’t hear about,” said Yvette Cruz, a spokesperson for the Florida Farmworker Association.
“I think it’s grossly underreported,” said Doug Casa, who heads research on heat illness at the University of Connecticut’s Korey Stringer Institute. “Laboring in the heat is one of the main reasons to have cardiac events…When a worker dies in the heat of a cardiac event, it’s getting recorded as a cardiac event, it’s not going down as the heat that caused it.”
“If a person’s not a U.S. citizen or they’re working here illegally, we’ll basically never hear about those cases,” Casa added.
This climate report is funded by Florida International University and the David and Christina Martin Family Foundation in partnership with Journalism Funding Partners. The Miami Herald retains editorial control of all content.
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