It’s not the disease-carrying mosquitoes, the scorpions, or the 22-kilogram tanks full of pesticide strapped to his back that Wendell Van Pelt fears. It’s the heat. This summer, while spraying insect-killing chemicals in the gardens of the rich in Greater Scottsdale, Arizona, Van Pelt has endured temperatures well in excess of 110 degrees Fahrenheit. Stepping past velvety green lawns and lagoon-like pools on his rounds, the field training manager at Mosquito Squad, a pest control service, has at times felt like he's “living in an oven.”
But Van Pelt has had respite from the scorching conditions: a cloak of cooling power wrapped around his torso—a vest filled with ice. “I love it,” he says, describing how his backpack filled with pesticide or natural repellent seems to amplify the effect: “That backpack is almost pressing the cold into your back. It just feels fantastic.”
Van Pelt knows that heat stress can be very dangerous. Everyone should be mindful of the risks, he emphasizes. And due to climate change and multiple recent heat waves, awareness of those risks is growing around the world. Millions of workers who toil outside, or in indoor spaces where temperatures can climb to unbearable levels, are increasingly adopting special strategies to cope. Cooling garments—vests, hats, and scarves—are among them.
It was only last year that Mosquito Squad rolled out cooling vests to employees in Greater Scottsdale. Many other firms are taking the same step, from power companies to real estate management businesses. Cooling vests have actually been around for decades, but in recent years their popularity, and variety, has exploded. Choosing the right one could potentially make the difference between going home after a good day’s work or heading to the ER. Over the past decade, hundreds of workers have died from environmental heat exposure in the US, according to the Bureau of Labor Statistics.
For Van Pelt, activating the cooling properties of his vest means stuffing it with flat, flexible packs of water ice straight from the freezer. These gradually melt as he works, but they can keep him cool for hours, he explains. There are many other technologies available.
Some use packs that contain fluids other than water—known as “phase change materials,” or PCMs. As these materials transition from solid or semisolid to liquid, they soak up heat, because this phase change requires energy. Non-water PCMs can be concocted in such a way as to remain flexible when cold or have higher melting points, which helps them last longer while maintaining a constant comfortable temperature. Other vests have tubes through which water is pumped around the wearer’s torso, or you might choose one with built-in fans that blow air directly onto your body. Finally, some vests are simply made with highly breathable fabric. Depending on the design and accessories, a top-of-the-range cooling vest could set you back close to $400.
“Demand this year has been so strong that just a few customers consumed 100 percent of our manufacturing capacity for months,” says Justin Li, cofounder and CEO of Qore Performance, a Tennessee-based firm that makes panel-like containers that you fill with 1.5 liters of water, freeze, and then sling against your chest, back, or both. A pair costs $148, and you can drink the water in them, via a tube, as it melts. Li got the idea, he explains, after talking to a soldier serving in Afghanistan, who told him how he and his comrades would put a frozen water bottle inside their body armour to try and stay cool while out on patrol. “We just reshaped it,” says Li.
Qore Performance has sold tens of thousands of the special water bottles, called IcePlates, to military personnel, Li estimates, but he has lots of commercial customers too. The surge in orders this year was largely driven by companies buying the devices for employees as heat waves erupted in the US and Europe. Known users of the IcePlate include factory staff, schoolyard supervisors, and fast-food workers, he says.
Meanwhile, in the Netherlands, EZ Cooldown has found clients for its cooling vests among roofers, cargo loaders, and TV production staff. But that’s not how things started. “The cosplay community and the fur-suit community was the group that I targeted first,” says Pepeyn Langedijk, founder and co-owner, who is himself a furry—someone who enjoys socializing while dressed in an animal-like furry suit.
Such suits are very hot, but they’re designed to look sleek—no one wants to wear a bulky cooling vest underneath them, even if the effect feels pleasant. Langedijk has a solution: a highly contoured, slimline vest, into the lining of which you can slip packs filled with a frozen, vegetable-oil-based fluid. “We have packs made to our specifications,” he says. “That product is something I created myself.”
Depending on how hot the user is at the time, EZ Cooldown’s packs might provide cooling for up to several hours. Once melted and no longer cool, they can be swapped out for a fresh set of packs straight from the fridge or freezer. Like Li, Langedijk says demand is booming—sales are up 35 percent this year, and he’s noticed rising interest from places like Scandinavia, where, he suggests, people are less adapted to the heat waves that are becoming more common there.
A lot of the vests require the user to swap out expired cooling components for fresh ones. Once the cooling substance has done what it can and has warmed up, the vest might in theory make things worse, since the wearer is then left with an unnecessary additional layer of clothing, notes Sarah Davey, an assistant professor at Coventry University in the UK who researches work and exercise in extreme environmental conditions, and who has studied cooling vests.
“They can help. However, we’ve seen that the effectiveness varies,” adds Andreas Flouris, an associate professor in the Department of Exercise Science at the University of Thessaly in Greece. “It varies based on the system that you use, and it also depends on the environmental conditions.”
Flouris has studied the use of cooling vests by a variety of workers—including those who helped to build stadiums for last year’s FIFA World Cup in Qatar. He has also observed trials involving grape pickers in a Cypriot vineyard. In that scenario, vests with built-in fans proved problematic. They kept sucking vegetation against the workers’ clothing, and the vests were very cumbersome to wear. Garments containing phase-change materials are almost always the best option, he says.
A particularly effective technique isn’t to wear a body vest at all, but to instead cool down a person’s head and neck before physical exertion, Flouris says. In one study, adolescent tennis players wore a cooling cap for 45 minutes until their core temperature dropped by half a degree Celsius. Flouris and colleagues measured this by asking the players to swallow a capsule that could record their core body temperature and broadcast it to a nearby receiving device. “The cooling effect is tremendous,” says Flouris. He explains that cooling the blood vessels in your head helps chill the rest of your body relatively quickly. In the study, when players used the cooling cap pregame, they had lower skin temperature throughout and felt, on average, 14 percent more comfortable than when they didn’t use it. There were also some small improvements in player performance too.
There may be resistance in some quarters from those unwilling to admit that they need help to survive blistering heat. Workers who spoke to WIRED confirmed that such attitudes are common. But the threat is real, stresses Tom Votel, president and CEO of Ergodyne, which makes a range of cooling garments. Workers who embrace such tools are no less tough than their colleagues—they’re just savvier, he argues. Research in the US suggests that heat stress results in thousands of workplace injuries annually.
By and large, employers aren’t yet protecting workers enough from excessive heat, says Juley Fulcher, worker health and safety advocate at Public Citizen, a nonprofit consumer advocacy organization. There are many cheaper alternatives to cooling gadgets too. It’s important to provide employees with water, fans, breaks in cool locations, or the option to adjust their schedules when temperatures rise, she suggests. “If you can keep them from experiencing heat stress, you’re going to get a lot more productivity out of them,” says Fulcher, noting the benefit to businesses.
Rutger Standaart, an account manager at Bertschat in the Netherlands, which sells cooling and heating garments, recently visited a company that uses welding machines. In the summer, temperatures by the machines can rise above 50 degrees Celsius, meaning that working for longer than 20 minutes at a time is unbearable. “With our cooling vests, they can work for an hour,” he says.
Fulcher says that cooling garments work best if they can be made lightweight and ergonomic. As the technology improves, she says, such devices could provide an alternative to energy-hungry air-conditioning in some situations—since AC is accelerating the climate crisis: “You’re going to see a lot more of these cooling vests used as an option around the world,” she says.
