A person-worn safety device that communicates bi-directionally and wirelessly with a remote receiver system. An accelerometer sensor detects the worker's activity levels to verify the worker's safety, and identify periods of unduly strenuous activity or undue lack of activity. The system also identifies worker position from localized radio signals from terrestrial sources. A manually actuable lever and button are usable by the worker to indicate a need for assistance. A visual or audio interface allows feedback to the worker originated by the device processor or remote server.