A personal safety alert system (PASS) device sounds an alarm to notify others that the wearer is in some sort of distress. These devices are often used by people who are in dangerous occupations and work as part of a team. For example, a firefighter might use a PASS device when he must enter a building to fight a fire or rescue its occupants. Typically, these devices send an alarm when the user has been motionless for a set amount of time, alerting coworkers or team members that the wearer is possibly in distress. Often, these devices have mechanisms in place that allow the wearer to reset them by moving a little in the event of a false alarm.
A PASS device is often used for the safety of firefighters. It emits a high-pitched alarm sound when a firefighter is in distress, alerting others of the need to rush to his aid. This type of device may be useful in the event that a firefighter becomes trapped in a building or realizes he is lost. It may also prove critical if he is injured or becomes incapacitated while fighting a fire.
In most cases, PASS devices work because of their motion-detecting abilities. They are set to deliver a high-decibel alarm when a user has remained motionless for a set amount of time. These devices usually have mechanisms in place to prevent false alarms, however. For instance, they might deliver warning tones to alert the user that he has been motionless long enough to cause the alarm to sound. If the user is not in distress, he can move a bit in order to prevent the sounding of the alarm.
PASS devices often have automatic reset abilities as well. For instance, if a firefighter hears the warning tones and moves to prevent the alarm from sounding, this doesn't interfere with a true distress alarm. Instead, the movement of the firefighter before the alarm usually resets the PASS device so that it is still ready to summon help for the firefighter.
Often, a PASS device also has a manual component that allows the user to summon help right away. This way, an individual who is in distress does not have to wait and attempt to remain motionless in order to get help. The moment he knows he is in danger, he can activate the alarm manually.