Atsusa is conducting A/B testing on heat tracking solutions to learn from experiments and progress deeper into metrics that matter.

We built Atsusa because heat illness is preventable, but nobody was preventing it. Heat kills outdoor workers, runners collapse mid-race, elderly people overheat in their homes. Garmin and Apple Watch measure your steps and heart rate—but they don't warn you before you hit the heat stress wall. Meanwhile, construction companies lose $20B annually to heat illness, insurers pay out claims, and OSHA has nowhere to turn. We realized the data was already there: heart rate, core temperature, and wet bulb globe temperature (WBGT). One algorithm. Works for anyone. A runner gets an alert to slow down. A construction crew gets a safety dashboard for the job site. An HR team automates heat-risk compliance. Three wearable ecosystems. One problem solved. Multiple revenue streams. No brainer. We're not interested in generic fitness apps. We're building the heat-safety layer that every organization needs as the planet heats up. The USA is our launch pad. Australia, Canada, and Asia are obvious next. Data licensing to insurers and government agencies is the moat. If you're building in wearables, health tech, or workforce safety—or if you've experienced heat illness and know we need better tools—let's talk.