atmospheres. It was reported that shortly after the events of September 11, 2001, the sound of many activated PASS devices could be heard beneath the rubble of the collapsed World Trade Center. 343 firefighters (including a chaplain and two paramedics) of the New York City Fire Department (FDNY) were killed on that day. See also References External links Personal Alert Safety Systems (PASS) Research PASS device sound Firefighting equipment de:Totmannmelder