On a scorching May 2020 day that topped out at 95 degrees, Austin resident Jos茅 Mario Calles reported to his landscaping job.
A lawsuit later filed by Calles鈥� family recounted what happened next: The 51-year-old, who financially supported his wife and kids in El Salvador, fainted. He was rushed to the hospital and spent two nights being treated for a heart condition and diabetes, both known to make people more vulnerable to heat.
The lawsuit claims that his employer did not report the incident to the Occupational Health and Safety Administration or to its worker鈥檚 compensation insurance carrier as required by law. The father of six returned to work without the necessary medical clearance, according to the lawsuit, hefting 40-pound bags of mulch. Twelve days after his initial collapse, he suffered a heart attack at a job site and didn鈥檛 wake up.
The Travis County Medical Examiner found the cause of death was myocarditis, an inflammation of the heart muscle. The autopsy did not mention heat.
Last year was the And the heat was particularly deadly: State records report that , the most heat-caused deaths on record. The count rises to 562 when including deaths where heat was a contributing cause.
Climate change is causing hotter days and nights, which put extra stress on the human body. The problem is likely to only get worse.
Yet deaths related to heat are almost certainly undercounted in Texas and nationwide, according to experts. Accounting for heat鈥檚 role in a death is notoriously difficult because of the subjectivity and complexity of the process. For example, doctors or local officials who fill out records listing the cause of death might not consider the weather on the day a person died or if a person routinely worked in the heat.
鈥淭he health impacts (of heat) are a little bit more subtle,鈥� said Sameed Khatana, assistant professor of medicine at the University of Pennsylvania and a cardiologist. 鈥淭hey can be delayed. And trying to tease apart whether a death or an adverse health effect occurred due to the temperature is quite challenging.鈥�
During a recent visit to Austin, Douglas Parker, assistant secretary of labor for occupational safety and health, called heat 鈥渢he most dangerous weather phenomenon that workers face.鈥�
Failing to accurately count how many people are dying from heat-related causes leaves officials unable to grasp the scope of the problem and work more directly to fix it, said Andrew Dessler, professor of atmospheric sciences at Texas A&M University.
鈥淎 lot of the argument over climate change is: Why should we care if temperature goes up a degree?鈥� Dessler said. 鈥淎nd this is one of the reasons why we should care.鈥�
Community organizers, scientists and academics say the lack of public information and understanding about heat deaths makes it hard to mount an effective local response to what they consider a public health crisis.
鈥淗ow do you tackle a problem if you don't know the size of the problem, if you don't understand the breadth and the depth of the problem?鈥� said Gregory Wellenius, an environmental epidemiologist and professor on environmental health at Boston University.
A data analysis by The Texas Tribune found that Texas likely failed to account for many heat-related deaths between 2013 and 2019. During those years, the state recorded 777 heat-related deaths. The Tribune鈥檚 estimate 鈥� calculated by comparing how many people died on abnormally hot days with how many people would have been expected to die during more average weather 鈥� found that 998 deaths were associated with heat during that period in the 41 most populous of Texas鈥� 254 counties.
Texas counties with medical examiners take varying approaches for how they document heat-related deaths. For example, Dallas County reports all deaths in which heat was suspected to be the cause of death or a contributing factor. In Nueces County, which includes Corpus Christi, an official said they don鈥檛 track heat-related deaths at all.
鈥淒eaths are investigated differently depending on where people die. We don't really have a federal death investigation system, every state runs a different death investigation system. And so the whole thing is pretty fragmented," said Gregory L. Hess, a chief medical examiner at Pima County in Arizona, which includes Tucson.
That means cases like Calles鈥� can fall through the cracks because heat wasn鈥檛 cited by the medical examiner as a possible contributor to his death. It鈥檚 not clear whether the medical examiner considered heat as a factor. In Travis County, only deaths that are directly caused by heat are recorded as heat-related.
John Escamilla, a McAllen attorney who sued Calles鈥� employer on behalf of the family and specializes in workplace accidents and injuries, said more people are coming to him seeking legal help for cases involving workers who have suffered heat-related injuries. The landscaping company BrightView, which purchased the company where Calles worked, declined to comment.
鈥淚 don't think employers consciously put their workers at risk. I think they're ignorant or they don't really care,鈥� Escamilla said. 鈥淏ut these summers are getting more and more intense for longer periods of time.鈥�
A silent killer that鈥檚 difficult to diagnose
For some deaths, the role heat played is clear: In June 2023, a 68-year-old man was found dead on the couch in his Fort Worth home. A death investigator found that the air conditioning was broken and the temperature inside the house was 91 degrees.
The same month, a 28-year-old man was found having "seizure-like activity" in a Fort Worth strip mall parking lot. His core body temperature was measured at 108 degrees at the hospital. His muscles broke down, his brain swelled and there was evidence of liver failure, according to an autopsy.
On Aug. 25, 2023, a 48-year-old woman was admitted to a suburban Houston hospital with a body temperature of 108.1 degrees. She鈥檇 sat outside for an hour, according to an autopsy.
Heat kills people when the body cannot cool itself and a person doesn鈥檛 take action soon enough to cool their body. In hot weather, the body redistributes warm blood to the skin to protect internal organs. Sweat evaporates, cooling the skin and lowering the temperature of the blood beneath.
But if it鈥檚 too hot, a person is exerting themselves physically or remains in the heat too long, the body can heat up faster than it鈥檚 able to handle. The heart races as it goes on overdrive to circulate blood throughout the body. Blood pressure drops.
If the person doesn鈥檛 drink water and escape from the heat, the next phase is heat exhaustion, marked by weakness, profuse sweating, headaches or dizziness. Without adequate treatment, the situation can progress to heat stroke, when body temperature can spike to 103 degrees or more and vital organs like kidneys, heart and brain become starved for oxygen 鈥� a potentially deadly situation.
鈥淧eople often are unaware that heat is starting to cause [health] problems, and, by the time they're aware of it, it can be too late,鈥� said Kristie Ebi, a professor and expert on heat鈥檚 health risks at the University of Washington Center for Health and the Global Environment.
But often, figuring out the role heat played is more difficult. Experts refer to heat as a silent killer because the harm it causes isn鈥檛 necessarily clear or sudden.
Teasing out whether heat contributed to a death becomes subjective. Experts who fill out death forms 鈥� including physicians, medical examiners and local justices of the peace, who all have varying levels of training 鈥� have different thresholds for when they feel they have enough information to list heat as a direct or contributing factor to a death.
It also takes time and effort to track down information about the circumstances that preceded someone鈥檚 death to look for clues that may point to heat as a contributor. Was the person suffering in a hot home? Living under an overpass? Playing tennis in the heat?
鈥淚t also depends on peoples鈥� need for a level of precision,鈥� said Scott Sheridan, a geography professor at Kent State University in Ohio who obtained a Ph.D. in climatology. 鈥淎nd that's where I think heat tends to be one of the most difficult to convey. 鈥� We all think about the runner that collapses in the heat, or some very obvious case, but the vast majority of cases just aren't that obvious.鈥�
And even with an autopsy, the picture might still be murky, said Bob Anderson, a branch chief in the division of vital statistics at the U.S. Centers for Disease Control and Prevention, which assigns codes to the state鈥檚 death data so it can be analyzed.
Say an elderly person with heart disease who gardens frequently is found dead outside 鈥� did heat play a role?
鈥淪o it can vary according to the quality of the death investigation that's done, and how much information is gleaned,鈥� Anderson said. 鈥淏ut even the best death investigation won't always tell you whether heat played a role or not.鈥�
In Arizona, medical examiners hunt for heat deaths
Experts say the model for how to more thoroughly investigate and count heat deaths is Maricopa County, Arizona, in the Sonoran Desert, which is home to around 4.6 million people, including in Phoenix, and regularly reaches temperatures of 110 in the summer. The county medical examiner鈥檚 office has been working since 2006 to catch every death that could have been related to heat, Chief Medical Examiner Jeff Johnston said.
Their reviews are thorough: When pathologists receive a case, they do an autopsy and they consider medical history, information from the place the person died and recent events to determine if heat contributed to the death, JoJohnston knows his office isn鈥檛 catching every case 鈥� that would require investigating every single death, even when heat isn鈥檛 suspected, which is cost-prohibitive. But he argues they have one of the most robust systems in the country for detecting heat-related deaths. In 2018, they even coined a category for them: environmental heat exposures.
Assistant Medical Director for the Maricopa County Department of Public Health Nick Staab said local officials use this data to inform their strategies for how to help Maricopa County residents stay cool.
Maricopa County used the data to support doubling the county鈥檚 network of cooling centers operated by local groups and cities to more than 100 and Arizona 2-1-1 coordinates free transportation to the centers.
They鈥檝e also partnered with community health workers, or promotoras, to supply information on how to beat the heat and find cooling centers in English and Spanish.
hnston said.
鈥淭he devil鈥檚 in the details really with these,鈥� Johnston said.
and gather demographic and behavioral data to understand who is dying and why they were at risk.
鈥淲e strongly believe in public health that all of these deaths are preventable,鈥� Staab said, adding, 鈥淲e鈥檙e trying to tell this story. We鈥檙e trying to define extreme heat as a public health emergency so that we can get additional funding, additional resources to bring to our high risk population.鈥�
In Texas, most of the biggest urban areas have medical examiners to investigate deaths. But those offices don鈥檛 investigate every death: Texas law requires an investigation in circumstances such as a suspected suicide or homicide, or when a person dies within 24 hours of being admitted to a hospital.
Dr. Jessica Dwyer, a medical examiner for Dallas County, said tracking heat-related deaths is inherently complex because no single method fits all cases. A death involving drug ingestion on a hot day might be classified differently depending on the medical examiner鈥檚 judgment. Dwyer said this variability stems from differences in training, office protocols, and personal experience.
鈥淪tandardizing it becomes a little difficult because not every case is the same," Dwyer said.
Some than others. This includes older residents, children, and people with chronic diseases. People experiencing homelessness and migrants trying to cross vast stretches of brushland on foot also contend with the dangers of heat more than people who spend much of their time indoors.
On the outskirts of El Paso, 12 people died from heat during the summer of 2023 while trying to immigrate through the blazing Chihuahuan Desert. Many more died in neighboring Sunland Park, New Mexico.
鈥淓very summer, we've really tried to shoot for zero deaths,鈥� said Graciela Ortiz, who coordinates the Extreme Weather Task Force in El Paso. 鈥淚 am going to tell you, though, we blew the record out of the water last year. I was shocked.鈥�
In Dallas last year, Rose Jones, a public health professional, said she was shocked to hear stories from friends who worked in an emergency room about homeless patients arriving with third-degree burns from falling asleep on the pavement. It unsettled her so much that she decided to quit her job with an urban forestry group to start a consulting practice focused on protecting people from extreme heat. She knew people such as undocumented workers and prisoners would suffer first.
鈥淭hese are all marginalized groups so in general it鈥檚 not going to get a lot of attention. People will just go into their air conditioned homes,鈥� Jones said.
In San Antonio, Lotus Rios saw the heat鈥檚 danger grow. The 45-year-old community leader, indigenous activist and mother of two runs a small food pantry where needy neighbors can eat for free. Over the years, life has become more difficult as the city鈥檚 tree cover gave way to more concrete, and summer temperatures grew warmer.
鈥淧eople used to be able to survive with a box fan in the window, that鈥檚 not the case anymore,鈥� Rios said. 鈥淔ans are not helpful when it鈥檚 104.鈥�
She sees a lot of suffering in her line of work. But nothing was as hard to bear as the story of Albert Garcia.
Garcia lost both legs to frostbite while living outside when Winter Storm Uri plunged Texas into subfreezing weather for a week in February 2021. Later, Rios and others helped secure shelter for Garcia. But he suffered incontinence and felt abused by shelter workers. A year later, he was back under an Interstate 35 overpass.
Garcia used drugs. He liked to preach from the Bible and make jokes. He often made Rios laugh.
In August 2023, after more than 50 consecutive days of triple-digit weather, Garcia died beneath the overpass where he slept. The local news website Deceleration told his story in a .
When journalist Greg Harman, founder of Deceleration, went to the site of 骋补谤肠颈补鈥檚 death, several days later, he measured the temperature at 114 degrees.
骋补谤肠颈补鈥檚 , obtained by Deceleration, said he died of a drug overdose. He had heroin in his system. But it also noted his last known use was on the morning of Aug. 11, nearly a day before his death 鈥� and overdose deaths typically happen soon after someone uses drugs.
鈥淗e was somebody,鈥� Rios said. 鈥淗e didn鈥檛 have to die the way he did.鈥�
Last week, Harman and 500 other signatories to the San Antonio City Council, asking it to produce a count of heat fatalities in the area.
On Monday, after repeated correspondence with the Tribune, the public information officer for Bexar County provided a count of hyperthermia fatalities. It showed 12 deaths in 2023, five times the annual average for the 10 prior years (not counting heat-related mass casualty events in 2017 and 2022 when dozens of migrants died locked in hot tractor-trailers).
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