On a hot summer day in Oak Ridge, Tennessee, dozens of men removed pipes, asbestos and hazardous waste as they cleaned up a nuclear power plant and prepared it for demolition.
Dressed in head-to-toe coveralls and respirators, the crew members working in a building without power had no visible relief from the heat. Instead, they wore bracelets that recorded their heart rate, movement and exertion levels for signs of heat stress.
Stephanie Miller, a safety and health manager for a U.S. government contractor doing cleanup work at Oak Ridge National Laboratory, watched a nearby computer screen. A color-coded system of tiny bubbles showing each worker’s physiological data alerted her if anyone was in danger of overheating.
“Heat is one of the biggest risks we face in this job, even though we’re dealing with high radiation, dangerous chemicals and heavy metals,” Miller said.
As the world continues to experience record-high temperatures, employers are exploring wearable technology to help keep workers safe. New devices collect biometric data to estimate core body temperature — an elevated temperature is a symptom of heat exhaustion — and encourage workers to take cool-down breaks.
The devices, originally developed for athletes, firefighters and military personnel, are now coming into use at a time when the Atlantic Council estimates that heat-induced losses in worker productivity could cost the U.S. about $100 billion annually.
But there are concerns about how the medical information collected about workers is protected, with some unions concerned that managers could use it to punish people for taking necessary breaks.
“Anytime you put a device on a worker, they’re worried about tracking, privacy, how are you going to use this against me,” said Travis Parsons, director of occupational safety and health at the Laborers’ Health and Safety Fund of North America. “There’s a lot of exciting stuff going on, but there’s no guardrails around it.”
VULNERABLE TO HEAT
At the Tennessee cleanup site, workers wear heat stress monitors from Atlanta-based SlateSafety, an employee of United Cleanup Oak Ridge. The company is a contractor for the U.S. Department of Energy, which has regulations to prevent overheating in the workplace.
But most American workers have no protection from extreme heat because there are no federal regulations requiring it, and many vulnerable workers don’t speak out or seek medical attention. In July, the Biden administration proposed a rule to protect 36 million workers from heat-related illnesses.
According to the Environmental Protection Agency, 986 workers in the U.S. died from heat exposure between 1992 and 2022. Experts suspect the number is higher because a coroner may not list heat as the cause of death when a sweltering roofer falls to his death.
Establishing standards for occupational safety can be tricky, because people react differently to heat. That’s where wearable makers hope to help.
HOW PORTABLE HEATING TECHNOLOGY WORKS
Employers have monitored workers for heat-related stress by checking their temperatures with thermometers, sometimes rectally. More recently, firefighters and military personnel have swallowed thermometer capsules.
“That just wouldn’t work in our work environment,” said Rob Somers, global director of environment, health and safety at consumer products company Perrigo.
Instead, more than 100 workers at the company’s infant formula plants were fitted with SlateSafety bracelets. The devices estimate a wearer’s core temperature, and a reading of 101.3 degrees triggers an alert.
Another SlateSafety customer is a Cardinal Glass plant in Wisconsin, where four masons maintain a furnace that reaches temperatures of 1,500 degrees Celsius.
“They’re right up against the wall. So it’s them and fire,” said Jeff Bechel, the company’s safety manager.
Cardinal Glass paid $5,000 for five wristbands, software and air monitoring hardware. Bechel believes the investment will pay off; two heat-related emergency room visits by an employee cost the company $15,000.
Another wearable device, made by Massachusetts company Epicore Biosystems, analyzes sweat to determine when workers are at risk of dehydration and overheating.
“Up until a few years ago, you would just wipe (the sweat) off with a towel,” said CEO Rooz Ghaffari. “Turns out there’s all this information tucked away that we’ve forgotten.”
Research has shown that some devices successfully predict core body temperature in controlled environments, but their accuracy remains unproven in dynamic workplaces, experts said. A 2022 research review said factors such as age, gender and ambient humidity make it difficult for the technology to reliably measure body temperature.
The suit-clad workers at United Cleanup Oak Ridge can get sweaty before they even start demolishing. Managers see dozens of sensor alerts every day.
Worker Xavier Allison, 33, was removing heavy sections of pipework during a recent heat wave when his machine vibrated. Because he was working with radioactive materials and asbestos, he couldn’t go outside to rest without undergoing a decontamination process, so he spent about 15 minutes in a nearby room that was just as hot.
“You just sit by yourself and do your best to cool off,” Allison said.
The bracelet alerts workers when they have cooled down enough to resume work.
“Since we implemented it, we’ve seen a significant decrease in the number of people needing medical attention,” Miller said.
COLLECTION OF PERSONAL DATA
United Cleanup Oak Ridge uses the sensor data and an annual medical exam to determine work assignments, Miller said. After noticing patterns, the company sent some workers to their personal doctors, who discovered heart problems the workers didn’t know about, she said.
At Perrigo, managers analyze the data to find people with multiple reports and talk to them to see if there’s “a reason why they can’t work in the environment,” Somers said. The information is organized by identification numbers, not names, when it comes into the company’s software system, he said.
Companies that keep years of medical records raise concerns about privacy and the possibility that bosses could use the information to kick workers off their health plans or fire them, said Adam Schwartz, director of privacy litigation at the Electronic Frontier Foundation.
“The device could honestly hurt, because you could raise your hand and say, ‘I need a break,’ and the boss could say, ‘No, your heart rate is not elevated, go back to work,’” Schwartz said.
To minimize such risks, employers should give their workers the option to wear or not wear monitoring devices, process only strictly necessary data and delete the information within 24 hours, the spokesperson said.
Wearing such devices can also expose workers to unwanted marketing, said Ikusei Misaka, a professor at Musashino University in Tokyo.
A PARTIAL SOLUTION
The National Institute for Occupational Safety and Health advises employers to develop a plan to help workers adapt to hot conditions and to 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 more work is needed to determine their accuracy, said Doug Trout, the agency’s chief medical officer.
The technology must also be accompanied by access to breaks, shade and cool water, as many workers, especially in agriculture, fear reprisals if they take breaks to cool down or hydrate.
“If they don’t have water to drink, and the time to do it, it doesn’t mean much,” said Juanita Constible, senior attorney at the National Resources Defense Council. “It’s just something extra they have to carry when they’re out in the hot fields.”
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Yuri Kageyama in Tokyo contributed to this report.