This safety advisory was issued in response to the results of an investigation by the NIOSH Fire Fighter Fatality Investigation and Prevention Program (FFFIPP). The FFFIPP investigated a September 16, 2019, incident in which a firefighter died in the line of duty and six others were hospitalized. A fire department responded to a propane leak at a newly renovated office building. Several firefighters entered the building. The propane gas ignited and caused an explosion.

The investigation determined that the odor fade of mercaptan was a key contributing factor. Mercaptan is a sulfur-containing compound, which is described as smelling like a rotten egg or rotten cabbage. It is intentionally added to natural gas, butane, and propane to give it a distinct odor for safety purposes. The odorant alerts building occupants to a gas leak.

The investigation also discovered that some fire departments may not fully understand how the odor fade of natural gas or propane can occur.

The NIOSH safety advisory contains several recommendations for fire departments to ensure the safety of firefighters responding to natural gas or propane incidents, including using gas detection equipment rather than relying solely on sense of smell to determine the presence of these gases, and developing an understanding of how these odorants added to natural gas or propane can fade.

Read the complete NIOSH safety advisory bulletin by clicking the link below.