What function does a PASS device serve?

A Personal Alert Safety System (PASS) device is vital for firefighter safety, as it is specifically designed to alert others when a firefighter is in distress. This device emits a loud audible alarm if it is manually activated or if it stays motionless for a predetermined period, signifying that the firefighter may be unable to move or is in danger. The primary function of a PASS device is to enhance personal safety by ensuring that other team members can respond quickly to a potential emergency involving one of their own.

In the context of the other options, measuring air quality, indicating fire proximity, and providing navigation assistance are functions that do not align with the specific purpose of a PASS device. While other equipment may serve those functions, the core role of the PASS device focuses on alerting others to a firefighter's distress, making it a crucial tool for personnel safety in hazardous environments.