On a hot summer day in Oak Ridge, Tennessee, dozens of men removed pipes, asbestos and hazardous waste as they worked to decontaminate a nuclear facility and prepare it for demolition.
Dressed head-to-toe in coveralls and equipped with respirators, crew members had no significant relief from the heat in a building without electricity. Instead, they wore wristbands that tracked their heart rate, movements and exertion levels to detect signs of heat stress.
Stephanie Miller, a safety and health manager for a U.S. contractor doing cleanup work at Oak Ridge National Laboratory, watched a nearby computer screen. A color-coding system with small bubbles showing each worker’s physiological data alerted her when any of them were in danger of overheating.
“Heat is one of the biggest risks we face in this work, even though we work with high levels of radiation, dangerous chemicals and heavy metals,” Miller said.
As the world experiences more record-breaking temperatures, employers are exploring wearable technology to keep their workers safe. New devices capture biometric data to determine core body temperature—an elevated temperature is a symptom of heat exhaustion—and prompt workers to take cool-down breaks.
The devices, originally designed for athletes, firefighters and military personnel, come at a time when the Atlantic Council estimates that heat-related labor productivity losses could cost the United States about $100 billion annually.
However, there are concerns about the security of medical data collected on employees, with some workers’ associations fearing that managers could use this data to penalize employees for taking necessary breaks.
“Any time you put a device on a worker, they’re very concerned about tracking, privacy and how can you use this against me,” said Travis Parsons, director of occupational health and safety at the Laborers’ Health and Safety Fund of North America. “There are a lot of exciting things out there, but there are no guardrails for it.”
The workers at the Tennessee cleanup site wearing heat stress monitors made by Atlanta-based SlateSafety are employed by United Cleanup Oak Ridge, a contractor with the U.S. Department of Energy, which has regulations to prevent overheating in the workplace.
But most U.S. workers lack protection from extreme heat because there are no federal regulations and many at-risk workers don’t report or seek medical attention. In July, the Biden administration proposed a rule that would protect 36 million workers from heat-related illnesses.
According to the U.S. Environmental Protection Agency, 986 workers died from heat exposure in the United States between 1992 and 2022. Experts suspect the number is even higher because a coroner may not list heat as the cause of death if a roofer suffers a fatal fall in sweltering heat.
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Setting occupational safety standards can be difficult because everyone reacts to heat differently. This is where wearable device manufacturers want to help.
HOW PORTABLE HEATING TECHNOLOGY WORKS
Employers have identified heat-related symptoms in workers by taking their temperatures with thermometers, sometimes rectally. More recently, firefighters and military personnel have swallowed thermometer capsules.
“That simply wouldn’t have worked in our work environment,” said Rob Somers, global director of environment, health and safety at consumer goods maker Perrigo.
Instead, over 100 employees in the company’s infant formula factories were equipped with SlateSafety wristbands. The devices measure the wearer’s core body temperature and trigger an alarm when the reading reaches 38.5 degrees.
Another SlateSafety customer is a Cardinal Glass factory in Wisconsin, where four masons maintain a furnace that reaches 3,000 degrees Fahrenheit.
“They’re right up against the wall. So it’s them and the fire,” said Jeff Bechel, the company’s safety manager.
Cardinal Glass paid $5,000 for five wristbands, software and air monitoring devices. Bechel believes the investment will pay off; one employee’s two heat-related emergency room visits cost the company $15,000.
Another portable device, made by Massachusetts-based Epicore Biosystems, analyzes sweat to determine when workers are at risk of dehydration or overheating.
“Until a few years ago, you would just wipe off the sweat with a towel,” said CEO Rooz Ghaffari. “It turns out that all this information that we were missing is hidden there.”
Research has shown that some devices can successfully predict core body temperature in controlled environments, but their accuracy in dynamic workplaces is not yet proven, experts say. A 2022 research review found that factors such as age, gender and ambient humidity make it difficult to reliably measure body temperature with the technology.
Clad in protective gear, United Cleanup Oak Ridge workers can start to sweat even before demolition begins. Managers see dozens of sensor alerts every day.
Worker Xavier Allison, 33, was removing heavy pieces of pipe during a heatwave when his equipment vibrated. Since he was working with radioactive material and asbestos, he couldn’t go outside to rest without going through a decontamination process, so he spent about 15 minutes in a nearby room that was just as hot.
“Just sit by yourself and try to cool down,” Allison said.
The bracelet notifies the worker when he or she has cooled down sufficiently and can resume work.
“Since we introduced the system, the number of people needing medical attention has dropped significantly,” Miller said.
United Cleanup Oak Ridge uses the sensor data and an annual medical exam to determine work assignments, Miller said. When the company noticed patterns, it sent some employees to their primary care doctors, who discovered heart problems the employees hadn’t known about, she said.
At Perrigo, managers analyze the data to find people with multiple alerts and talk to them to find out if there is “a reason why they can’t work in that environment,” Somers said. The information is sorted by identification numbers, not names, when entered into the company’s software system, he said.
The fact that companies retain medical data for years raises concerns about privacy and whether bosses could use the information to kick an employee off health insurance or fire them, says Adam Schwartz, privacy litigation director at the Electronic Frontier Foundation.
“Honestly, the device might hurt because you could raise your hand and say, ‘I need a break,’ and the boss might say, ‘No, your heart rate is not elevated, go back to work,'” Schwartz said.
To minimize such risks, employers should give their employees the choice of whether or not to wear monitoring devices, process only absolutely necessary data and delete the information within 24 hours, he said.
Wearing such devices can also expose workers to unwanted advertising, says Ikusei Misaka, a professor at Musashino University in Tokyo.
The National Institute for Occupational Safety and Health advises employers to develop a plan to help workers adapt to hot conditions and train them to recognize signs of heat-related illness and provide first aid. Wearable devices can be part of efforts to reduce heat stress, but their accuracy needs more study, says Doug Trout, the agency’s medical officer.
The technology must also be accompanied by the possibility of breaks, shade and cold water, as many workers, especially in agriculture, fear retaliation if they take a break to cool off or drink.
“If they don’t have water to drink and don’t have time to drink it, it doesn’t mean much,” said Juanita Constible, senior attorney at the Natural Resources Defense Council. “It’s just something extra they have to carry around when they’re in the hot fields.”
