This article was produced as a project for USC Annenberg’s Center for Climate Journalism and Communication and Center for Health Journalism 2025 Health and Climate Change Reporting Fellowship.
Workers die from heat exposure on the job every year in Arizona, but the exact number of annual workplace heat fatalities in the state is unclear.
The Occupational Safety and Health Administration says heat-related deaths, illnesses and injuries are vastly underreported in U.S. workplaces. But OSHA estimates about 559 workers nationwide die from workplace heat exposure, and more than 24,000 workers experience heat-related illnesses or injuries annually.
Arizona has never had state regulations specifically to protect workers from heat. And as climate change drives more intense heat waves, heat-related worker deaths in Arizona appear to be increasing at a faster rate than in neighboring California, where state regulations for workplace heat safety have been in place since 2005, according to a recent study in the journal Health Affairs.
By examining records from OSHA, the Arizona Division of Occupational Safety and Health, and county medical examiners, KJZZ found dozens of examples of heat-related worker deaths in Arizona dating as far back as the 1980s. Victims ranged in age from 23 to 66 and worked in industries including agriculture, construction, landscaping and postal work. Here are ten of their stories:
Leonard Perez, 56, USPS postal worker
Phoenix, Sept. 3, 2025
Leonard Perez was only in his third week delivering mail for USPS when he collapsed on a sidewalk along his route on Sept. 3, 2025. The high temperature in the Phoenix area reached 106 that afternoon. The delivery truck Perez had been driving did not have air conditioning. A coworker found Perez after his GPS tracking system showed a period of inactivity. Emergency workers took Perez to a hospital where he was pronounced dead. The Maricopa County Medical Examiner listed hypertension and cardiovascular disease as Perez’s primary causes of death, but noted heat exposure was a contributing factor.
Matt Nelson, 58, HVAC technician
Dewey, July 1, 2025
Matt Nelson, 58, was a longtime HVAC technician working in an attic in Yavapai County on July 1, 2025. The high temperature in the Prescott area that day reached 96 degrees, but attic temperatures can be much hotter than outdoor temperatures. Nelson became unresponsive and died from heat-related causes.
Colin Boni, 23, construction worker
Glendale, June 4, 2025
On June 4, 2025, 23-year-old Colin Boni was working on a construction site in Glendale. The high temperature that day reached 95 degrees. Boni complained about the heat and told coworkers he was not feeling well. He was placed in a truck with air conditioning, but became unresponsive. He was transported to a hospital where he was pronounced dead. The Maricopa County Medical Examiner's report listed environmental heat exposure as Boni's primary cause of death and noted obesity was a contributing factor.
Cody Treatch, 26, firefighter in training
Tucson, Aug. 13, 2024
Cody Treatch was a 26-year-old firefighter cadet on his second day of training in Tucson on Aug.13, 2024. Treatch was participating in a training exercise — walking 1.5 miles while wearing full firefighting gear, except for a mask. The high temperature reached 99 degrees that day. Treatch began to show signs of heat illness and asked to sit down. He sat against a wall and was given water but continued breathing heavily and sweating excessively. He became unresponsive and was transported to a hospital. His body temperature was recorded at 107 degrees. He was placed on life support and died 10 days later. Documents from the Arizona Division of Occupational Safety and Health investigation noted the employer had a written safety and health program, but it did not address heat-related hazards or how to identify symptoms of heat-related illnesses.
Dario Mendoza, 25, farmworker
Yuma, July 20, 2023
25-year-old Dario Mendoza was harvesting fruit on a farm in Yuma on the morning of July 20, 2023 when coworkers saw him walk away from his worksite and stumble to the ground. He was taken to a hospital, where he died from heat-related causes. Mendoza’s death occurred during an especially intense heat wave, even for July. Temperatures had climbed above 105 degrees every day for three weeks leading up to the day Mendoza died, and the high temperature that day reached 116 degrees.
Nicholas Holt, 48, landscaper
Mesa, August 15, 2015
Nicholas Holt, 48, was a landscaper working on a job in Mesa. He had been picking up tree trimmings for about an hour on the afternoon of Aug. 15, 2015. The high temperature that day was 115 degrees and the National Weather Service had issued an Extreme Heat Warning. According to an OSHA fatality report, Holt told his boss that he was not feeling well. The boss told Holt to sit in the shade and drink some water. A neighbor later found Holt slouched against a cinder block wall. The neighbor said Holt’s face was dry and pale and his eyes were constricted and fixed. A coworker performed chest compressions until help arrived, but Holt died from heat exhaustion.
Unidentified farmworker harvesting melons
Yuma, May 22, 2012
Yuma is one of the major producers of melons in the U.S. and melons typically must be picked in the hot spring and summer months. KJZZ identified multiple heat-related fatalities involving Yuma melon harvests. According to one OSHA fatality report, a farmworker harvesting cantaloupes died on May 22, 2012. The high temperature that day reached 108 degrees and the National Weather Service had issued an Extreme Heat Warning. The worker had told the foreman that he was feeling ill and went to sit down in the shade. When the site foreman returned a few minutes later, the worker was unconscious and not breathing. The worker was transported to a hospital, where he was pronounced dead.
Unidentified welder
Scottsdale, Sept. 1, 2011
According to an OSHA accident report, an unidentified worker with a Scottsdale welding company was installing handrails outside of a school building on Sept. 1, 2011, when he collapsed from heat-related causes and died. It was an exceptionally hot day for early September — the high reached 112 degrees and the low temperature that morning was 90. The National Weather Service had issued an Extreme Heat Warning for that date.
Unidentified farmworker
Tonopah, July 14, 1998
Heat stroke deaths in workplaces increase when temperatures rise, but multiple studies show vehicle accidents on job sites increase in hot weather too, as a result of exhaustion or impaired judgment. One OSHA fatality report details an incident in which a worker died on a farm in Tonopah on the afternoon of July 14, 1998. The report says the worker died because he was run over by a tractor. But it also notes that before he was run over, he had fallen off the tractor, likely due to heat exhaustion. The high temperature that day was 112 degrees.
Unidentified dairy worker
Tolleson, July 22, 1988
According to an OSHA fatality report, an employee on a Tolleson-area dairy farm was loading hay onto a tractor on the afternoon of July 22, 1988 when he began to complain of intense thirst and began drinking large amounts of water. He began walking erratically and having trouble speaking. He was transported to a hospital where he died of heat stroke. The high temperature in the area that day was 110 degrees.
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Arizona labor groups are calling for state regulations to require specific protections from heat in workplaces. But actions from the state have so far fallen short of what workers have called for. -
As the Industrial Commission of Arizona considers workplace heat safety recommendations, some employers say they would welcome new heat rules, but others worry about overregulation. -
Arizona's outdoor workers endure extreme temperatures. But Arizona does not have any specific state regulations requiring their employers to provide them with water, shade or breaks from the heat. -
Heat kills more people annually than any other type of weather-related event and outdoor workers face higher risks for heat illness. What makes working in the heat so dangerous?
