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Body-Worn Sensors Could Keep Responders Out of Heat Danger

The physiology-based heat-sensing technology monitors core body temperature and alerts the sensor’s wearer and a supervisor if the worker is in danger of a medical incident from heat exposure.

President Biden recently tasked the Occupational Safety and Health Administration with developing new rules for heat safety among workers, calling attention to an ongoing problem that is only projected to get worse with a warming climate.

This means workers who labor outside, such as construction workers, industrial workers or any who face potentially harmful temperatures. And that includes first responders, who know all too well the dangers of becoming overheated, especially firefighters.

Firefighters routinely risk their lives entering dangerously hot environs with no way of knowing when to stop and cool off. The firefighting industry has been teased by technology, such as wearable heat sensors, but few departments across the nation have them. The technology is now available, and at least one company is marketing sensors it says fit the needs of firefighters.

Kenzen makes wearable devices that monitor core body temperature and can alert both the worker and a supervisor if that temperature begins to reach a danger zone. The device has been tested thoroughly and has been used by firefighter training schools, as well as major oil and gas companies working with training crews.

Curt Floyd, retired deputy fire chief and now first responder technical lead for the National Fire Protection Association, said this type of device would be beneficial to today’s firefighter.

“Typically we do not monitor our own body heat other than through normal human awareness, which often is late to indicate that we may have a problem,” Floyd said. “At large or long-duration events, Incident Command will have a rehabilitation group set up to monitor firefighters once they exit the host zone.”

Floyd said the firefighters are monitored in several ways, including by body temp to prevent a medical condition from heat exposure. “If a firefighter had a device that they could easily read that tells them their body temp is increasing to dangerous levels, they would be more apt to take actions to prevent a medical event,” he said.

He said the biggest challenge would be the change in culture. “Firefighters are action-oriented and driven individuals, who when given a mission to search for possible trapped victims, they push their bodies and many personal warning signs aside to accomplish that mission.”

Heidi Lehmann, who founded Kenzen, acknowledged that “band of brothers” mentality and said the ability for a supervisor to monitor workers, and also monitor conditions as a whole through a dashboard, could help break down that culture of not wanting to opt out and take a break when fellow firefighters are in the battle.

“They don’t want to be the one person sitting down in the shade if everyone else is working,” Lehmann said. “So the safety manager also looks at the team to see if an alert has been ignored or if somebody is ready to go back to work so they can intervene.”

Lehmann described the device as being at the intersection of workforce safety technology and heat science and climate tech. It’s physiology based, with the front end of the platform worn on the worker's upper arm. It samples the worker’s physiology about every five seconds and collects tens of thousands of data points per work, per shift. That data translates into a message to the supervisor about the risk the worker is undergoing.

“The main measurement we’re looking for is core body temperature and then sweat rate,” Lehmann said. It’s accurate to within a 0.2 percent range of predicting core body temperature.

Lehmann founded Kenzen in 2016 and began commercially deploying the devices in 2020. In between there was a lot of research and development being done both in and out of the United States, including with sport teams such as the San Francisco 49ers. There are about a thousand of the devices around the globe, with the biggest verticals being construction and mining.

Last year, a record-breaking year for temperatures on Earth, there were more than 200 million Americans under heat advisories. With every 10 degree Fahrenheit temperature increase, causing a 393 percent increase in hospitalizations for heat exposure.