How this new wearable technology is fighting excessive heat

“In a clinical setting or lab, to measure the internal temperature of the body requires the measurement of rectal temperature or esophageal temperature, or different blood temperatures,” he said. “Those aren’t feasible in a work setting and in a bigger population setting. But how hot you get it, hot the inside of the body gets, is largely what determines the health risks of heat, as well as the productivity risk.”

For the public, Apple Watch, Galaxy Watch 5, and the Garmin watch can all detect skin temperature, primarily to track menstrual cycles. But to determine if someone is at risk of heat stress, wearable devices need to measure core body temperature, a capability they lack. Core body temperature measures the temperature of internal organs — like your heart, liver and brain, whereas skin temperature only captures your temperature on the surface.