Exposure to high-temperature environments may cause the loudness of personal alert safety systems alarm signals to be reduced, causing the alarm signal to become indistinguishable from background noise at the incident scene.

This problem was brought to the attention of the International Association of Fire Fighters and the National Fire Protection Association Technical Correlating Committee on Fire and Emergency Services Protective Clothing and Equipment and the NFPA Technical Committee on Electronic Safety Equipment by the National Institute for Occupational Safety and Health's Fire Fighter Fatality Investigation and Prevention Program.

NIOSH reported that, during the investigation of four firefighter fatalities that occurred from 2001 to 2004, PASS alarms weren't heard or were barely audible. The PASS alarms had been certified as compliant to NFPA 1982 (1998 edition) and involved both stand-alone and SCBA-integrated PASS.

Initial laboratory testing of PASS by the National Institute for Standards and Technology's Fire Research Division has shown this sound reduction to occur at temperatures as low as 300°F (150°C) and could affect all PASS. However, additional work is required to better characterize the thermal conditions (temperatures and exposure durations) that contribute to alarm signal degradation.

While the NFPA Technical Committee on Electronic Safety Equipment has been working to develop appropriate revisions to NFPA 1982 to address this issue, adequate solutions have not yet been presented. The committee, in cooperation with NIOSH and NIST, will continue to study the issue and will incorporate revisions into NFPA 1982 as solutions are developed and consensus around is achieved.

PASS has always been a “last resort call for help” for emergency services personnel who are unable to otherwise notify others that they are in distress. Firefighters should continue to activate and wear PASS whenever in hazardous areas of any incident, but they should also be aware that high temperatures could cause degradation of the alarm signal. Incident command should continue to apply all personnel accountability measures at all incidents to ensure the safe entrance and exit of personnel from hazardous areas. Direct supervision of operating companies or teams should provide for the safe operating locations of personnel and ensure that members don't freelance on the incident scene.

IAFF affiliates should report any PASS malfunctions and other problems with PASS functioning to the IAFF Department of Occupational Health and Safety by e-mail at safety@iaff.org or by phone at 202-824-9304. The IAFF will maintain this information, as well as notify NIOSH and NFPA.

For further information regarding the NIOSH Fire Fighter Fatality Investigation and Prevention Program, as well as NIOSH investigation reports, visit www.cdc.gov/niosh/firehome.html.