Temperatures this summer have been hotter than usual, a trend we have come to expect with climate change as records are continually surpassed. 

While many of us can ride out extreme heat in the comfort of air conditioned interior spaces, outdoor workers don’t have that option and must contend with the risks of serious injury which can be acute and long lasting. 

A fast growing market for wearable cooling products, both in high tech and low tech varieties, is attempting to meet the challenge. Among those products is the CülCan, made by the Tennessee based small business Black Ice.  

“If you can pull heat away from your hand, it'll cool your whole body down. And so that's what we've done with the CülCan. It's basically a five inch cylinder that contains our special coolant,” said Mike Beavers, co-founder of Black Ice. 

A key selling point of the product, according to Beavers, is that the coolant inside, which is a chemical composition Beavers designed, doesn’t get as cold as ice, so it is easier to use on a person’s skin. 

“You put it in ice water or a freezer… and then you just hold it in the palm of your hand,” he said. “That is now our most popular product. We sell tons of those things.”

Beavers said his business has been growing by about 30 percent a year over the last three years, an acceleration from its previous pace. The company has been around for about 20 years. 

Across the Atlantic, the Swiss company GreenTeg is also reporting growing demand for its continuous body temperature monitors, which are worn with a patch or a strap. The monitors are often employed by athletes who have to perform outdoors, said CEO and founder Wulf Glatz. 

“So this device can communicate then with your smartphone,” he said, “and it will estimate your core temperature and broadcast that value to that device.”

Being able to monitor core temperature can help with prevention. Unlike a simple thermometer which, if put against the skin, would only tell you the temperature on your skin, GreenTeg claims its monitors can measure the temperature inside the body. It is that core temperature that is key to whether someone is developing heat-related illness. 

Glatz says there’s growing interest in his company’s technology. They’ve been approached by organizations representing firefighters, the military, miners and airfield workers. 

“If there's an airplane landing, you need to unload the baggage. You can't wait for three hours for it to get cooler, but what you can do is to measure the individuals and really have them safe,” he said, “maybe you need to exchange teams in higher frequency, maybe you need to equip them with cooling gear.”

Brett Perkison, an environmental and occupational medicine specialist at UTHealth Houston, tested one of GreenTeg’s monitors in combination with cooling vests. In a small study, he found the combination approach helpful in limiting heat related illnesses among outdoor laborers. 

The problem with the personal cooling industry is that not all of the gadgets being sold to the public are proven to work. 

For example, ones that use fans to cool the body, such as ventilated helmets, are unlikely to do much in humid environments, said Fabiano Amorim of the University of New Mexico, who has studied heat stress on outdoor workers in Brazil and the U.S. 

“[Helmets with fans] can increase the comfort or let's say your perception to heat, but it's not reducing your temperature,” he said. 

Not reducing core body temperature on hot days can have serious consequences. The number of heat-related emergency room visits in the summer of 2023 totaled 120,000, according to the CDC. 

Heat stress can cause someone to get lightheaded and fatigued. More serious symptoms include seizures. Repeat exposure to heat stress  can permanently damage people’s kidneys, Amorim said. The condition can be fatal. 

“We have seen people 40, 50 years old, [who are] dying from chronic kidney disease. And, they don't have any factor that's related to the traditional chronic kidney disease. That's hypertension, obesity and diabetes. And, the only history these people have is working under hot environments,” Amorim said. 

Many people do not develop serious symptoms until it’s too late. That means employers must be proactive in employing cooling gadgets and strategies such as rest breaks in shaded areas, access to cool water, and access to bathrooms so workers feel confident in drinking plenty of liquids. 

But while more tools to avoid heat illness are coming to market, companies are not racing to adopt them. Many do not have adequate heat stress prevention programs at all. 

“There needs to be an acceptance by the business community, the public community, about the ramifications of heat stress. So I would hope that if we continue, instead of having 20% of businesses having an adequate heat stress prevention program, in 10 years, we'll have 80%,” Perkison said. 

Adopting cooling gadgets as part of prevention programs faces hurdles. Aside from concerns over efficacy, there is also the problem of measurement. Perkison said it is hard to tell when someone is struggling with heat before symptoms start. 

“There's not a lab value that we can get to identify when somebody has heat stress,” he said, which means that it is hard for companies to keep track of workers’ health and know when to take action, unless they use a digital monitor like the one provided by GreenTeg. 

Mike Beavers, the Tennessee-based inventor of the CülCan, said he has been surprised by the diversity of his client base, including the many people with multiple sclerosis who are using it. 

The disease of the central nervous system causes symptoms such as numbness and trouble walking which, for some, can worsen in heat. 

“We had one guy write us a full one page letter handwritten that basically he was bragging about the fact that he could actually go out and cut his yard now,” Beavers said.