In crop fields, on construction scaffolding, beside drive-through lanes, working conditions are getting hotter, igniting a small but fast-growing industry to cool workers down.
There are vests packed with ice and pressed against the skin, and others soaked in water to evaporate on the body. There are high-tech stickers that measure sweat content and core temperature. One commercial lab is attempting to make fabric that reflects sunlight, mimicking the skin of a desert ant.
Gus Lackerdas, a national sales manager at cooling-gear firm Techniche and parent company OccuNomix, has a quick and easy pitch for prospective buyers, who include developers, contractors and road pavers: “Not only can your people be more productive, which I know you want, but they’ll be safer, which I know your HR department wants.”
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It has been a successful pitch so far. By the company’s estimates, the cooling-gear sector has grown from $30 million to $100 million in sales over the past three years. Cooling products for Techniche and OccuNomix have brought in at least $3 million to $5 million in annual revenue over that span, Lackerdas said.
The new interventions offer alternatives to the well-established fundamentals of heat safety: water, rest and shade. In a warming world — 2023 is on track to be the hottest year in Earth’s recorded history, according to multiple recent climatological studies — those simple yet effective strategies may not be enough to keep workers safe, some experts say.
“We need a more robust kind of system in place for workers to be able to protect themselves,” said Roxana Chicas, a nurse and scientist at Emory University. “I think that includes cooling devices, personal protective equipment.”
Heat killed 121 workers between 2017 and 2022, according to federal data, but some research suggests the real number is much higher because heat-related deaths and injuries are often blamed on accidents or underlying health conditions. A 2021 study published by the IZA Institute of Labor Economics concluded that occupational injury data from California — a state used as a stand-in for federal measurements — may undercount heat-induced injuries by a fivefold margin.
Occupational cooling technology remains a largely unproven field, with a small body of academic research on certain devices in workplace settings. Much of the research has been conducted using athletes or military members, who are not reliable stand-ins for a civilian workforce, experts say.
But the U.S. economy cannot stop when it gets hot, said Justin Li, co-founder and CEO of Qore Performance, which makes ice vests. To a large extent, his business model relies on the idea that some employers will seek ways to keep work viable at any temperature.
“In a free market, it creates open space for your competition to beat you, because maybe you choose not to try to manipulate the environment,” Li said. “But what if your competitor does figure out how to manipulate that environment?”
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What are the options?
For Chick-fil-A franchisee Troy Seavers, the complaints hit a crescendo in 2020. Why, customers asked, were drive-through employees at his restaurant near Phoenix outside in the hottest part of the day?
So Seavers tallied the investments he made to keep workers safe in the desert heat and distributed the list to the customers who raised concerns.
He built a shade canopy over part of the drive-through and bought a misting station and a swamp cooler. At 100 degrees or more, drive-through workers must wear Qore ice vests. No one is allowed to work outside for more than an hour at a time, and all workers receive paid cooling breaks. Those working outdoors wear two-way radios in case they need to call for help.
“The guests need to see that I proactively am protecting my team from the sun,” he said. “I haven’t had a guest call me in three years.”
At Dutch Bros. Coffee, a popular West Coast chain with locations 10 minutes away, franchisee Josh Hayes purchased more than 200 ice vests for employees across multiple stores, he said. He bought extra freezers for each location, so there’s always another frozen vest available.
DPR Construction, a general contractor with worksites across the Sun Belt, distributes cooling caps and neck towels that can be dunked in water for evaporative cooling. During breaks, supervisors hand out electrolyte ice pops. But in the Southeastern United States, DPR worksites have started moving away from those items in favor of longer, better rest periods, said Lance Wafler, who leads the company’s field operations in the region.
Wafler’s break areas have complete shade and running water. At particularly hot sites, DPR will rent an air-conditioned storage container, he said, and put picnic benches inside. The company has cut down on overtime, especially during heat waves.
“We are very cautious of trying to push our craft of trying to work longer, harder because of several safety concerns,” Wafler said. “Heat illness is one of them. But construction is inherently hazardous.”
Still, on a construction site, no one asks whether it’s “too hot to work,” he said.
Qore’s ice vest, which presses cold surfaces against the back, sides and abdomen, has been used by fast-food chains such as Chick-fil-A, Raising Cane’s and Dutch Bros. Coffee.
Meanwhile, Techniche’s evaporative vest, common among industrial workers, can decrease skin temperature by 10 to 15 degrees Fahrenheit, the company says, depending on ambient humidity.
These interventions are supposed to interrupt the effects of heat, said Margaret Morrissey-Basler, an assistant professor of health sciences at Providence College. They’re designed to work by keeping the body cool enough that natural heat reactions don’t kick in, or start at a higher temperature.
That’s noteworthy, she said, because water, rest and shade are normally sufficient on their own. “If you don’t have those in your work environment, you’re already off to a bad start,” said Morrissey-Basler, who also works with the University of Connecticut’s Korey Stringer Institute to help employers put together heat safety protocols.
Water replenishes fluid, which ensures there’s enough blood in the body and allows you to keep sweating. Rest slows or stops aerobic activity, so your muscles don’t produce as much heat. Shade gets you out of direct sunlight, giving your body the ability to radiate heat to your surroundings.
Don Chernoff, founder of the commercial research firm Small World Sciences, is working with North Carolina State University and University of Chicago researchers to produce textiles for “clothing that essentially lets you wear the shade on your body.” Tiny pyramids built into the fabric are designed to deflect sunlight, much like the leaves of a tree overhead — or similar tiny pyramids on the skin of the Saharan silver ant.
The bugs are so well adapted to searing conditions, they venture out during the hottest periods of the day, feasting on the decaying carcasses of animals that died in the heat.
Chernoff’s firm and research partners have not yet been able to make an economically feasible textile that could be woven into garments. “It theoretically should work,” he said.
A few inventors have touted other new ideas.
For workers in construction and agriculture, CalidGear is a garment that can be worn underneath work attire, as opposed to cooling vests or towels normally worn on top of other clothes. Tayyaba Ali, a 24-year-old entrepreneur, is hoping to roll the product into another start-up that makes water filtration monitoring software.
Young Ko, a mechanical engineering PhD student at MIT, developed a cooling wrap that in tests reduced skin temperature by 50 degrees Fahrenheit in dry conditions.
Sheng Xu, a wearable-tech researcher and nanoengineering professor at the University of California at San Diego, and a team of graduate students created a battery-powered fabric patch designed to conduct heat away from the wearer.
Do any of these things work? The ideas are promising, Chicas of Emory University said, but many emerging heat devices haven’t yet faced sufficient scientific or job site scrutiny.
For example, Chicas and co-authors from Tulane University and Boston University studied the effects of cooling bandannas and ice vests on farm and landscaping workers in Florida in 2020. The bandanna did prove effective, reducing the odds that a worker’s core temperature exceeded the dangerous threshold of 100.4 degrees. But the vest did not: 40 percent of workers wearing it reported symptoms of heat-related illness, and 60 percent had core temperatures greater than 100.4 degrees.
Chicas noted that her sample of 84 workers was too small to draw definitive conclusions. But it was an encouraging start to more research, she said.
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What happens when you overheat?
When your body gets hot, hundreds of thousands of years of physiology kick in to cool you down.
Your heart pumps blood to the surface of your skin, where it’s not as warm. You sweat, causing water to evaporate off your body and provide relief, but it makes you lose fluid, decreasing blood supply.
When your internal temperature reaches around 100.4 degrees Fahrenheit, your body has to make difficult choices. Which organs are going to get that limited amount of blood?
Eventually, your body reacts like it’s fighting an infection, pitching your temperature even higher and shunting blood away from your skin to protect vital organs, said Pope Moseley, a research professor at Arizona State University’s College of Health Solutions.
“Then you’re really screwed because now you’re not cooling,” said Moseley, who is also an intensive-care physician.
Our bodies also adjust to regular high heat exposure in a process called acclimatization, which experts say can take about a week. Effective acclimatization yields cell-level changes that help us retain fluids and keep core temperature low. For example, Moseley said, a heat-acclimated body sweats at a cooler temperature — essentially leaving your internal air conditioner on. Your blood volume increases so your body doesn’t have to make as many tough choices.
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Tracking workers’ health signs
Because heat affects individuals differently, Moseley said, it’s hard to give workers solid health advice. One farmworker may be fine in conditions that are debilitating to a colleague an arm’s length away.
“We are not seeing the totality of the impact of heat,” Moseley said. “We are missing this massive number of people, both in the workplace and not, who are highly vulnerable, and we’re going to be seeing more of this.”
Some emerging technologies in the heat-safety industry are designed not to keep workers cool but to provide precise measurements of when they are in danger.
A skin patch developed by Epicore Biosystems measures sweat content and skin temperature and contains an accelerometer to measure work rate. The company markets the patches to industrial employers, CEO Roozbeh Ghaffari said. Bluetooth transmitters in each patch communicate to management when workers need more hydration, electrolytes or just a break. If a wearer sweats out 2 percent of their body weight, the patch vibrates.
“You can begin to predict based on the skin temperature and accelerometer data what risk profiles start to look like,” Ghaffari said.
Meanwhile, Chicas is researching a patch that’s worn on the chest and measures core temperature, respiratory function and other biomarkers to predict when heat strain, a precursor to the more dangerous heat stress and heat stroke, sets in. But she wonders whether employers will draw the right conclusions from the data.
Sensors can have their own drawbacks, said Andrea Matwyshyn, a professor in the law and engineering schools at Pennsylvania State University. In certain cases, she said, their accuracy can be affected by darker skin complexions, certain medications or even hair spray.
And sensor data by itself isn’t always a reliable predictor of health. A worker can feel ill without showing symptoms of heat stress. Data should always be combined with human feedback, she said.
There are also privacy concerns. A supervisor could use health sensor data to claim an employee isn’t working hard enough, Chicas noted. Matwyshyn has a similar worry and wonders whether a manager could use that data to weed out workers seen as too unhealthy.
“There’s always a trade-off,” Chicas said. “But doing nothing I don’t think is an option.”
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