Gas range

NIOSH releases fact sheet on odorant fade

The National Institute for Occupational Safety and Health, or NIOSH, released a fact sheet on odorant fade in natural gas and propane, an important issue that requires firefighters to be aware of it so they can operate safely around natural gas and propane.

Odorant is a liquid added to natural gas and propane that releases a smell in case of a leak. The smell alerts anyone nearby about a leak since natural gas and propane are naturally odorless. The odorant, mercaptan, can fade over time through absorption or oxidation as the leaking gas runs through soil or concrete. Drywall, plywood, and new piping can also strip the odorant from natural gas and propane.

The NIOSH Fire Fighter Fatality Investigation and Prevention Program (FFFIPP) released recommendations for firefighters responding to natural gas and propane incidents. They recommend the following:

  • The use of gas detection equipment in these events, and not relying on their sense of smell to determine if there is a leak of natural gas or propane
  • Understanding that odorants from natural gas or propane can fade
  • Being trained on the proper calibration, maintenance, and use of gas detection equipment to determine if a potentially explosive atmosphere is present
  • Recognizing that a lack of odor can result from natural gas or propane contacting soil, concrete, and a wide variety of building materials such as drywall, wood, and new piping storage tanks

The fact sheet noted an incident from September 2019 where a firefighter in Maine was killed and six others were injured when propane gas ignited at a newly renovated office building. NIOSH FFFIPP investigators identified odor fade as one of the key contributing factors in that tragedy.

In 2020, an explosion in Baltimore killed two people and highlighted the need for fuel gas detection.

NFPA 715 Standard for the Installation of Fuel Gases Detection and Warning Equipment is currently in the early development phase. The new standard will cover the selection, design, application, installation, location, performance, inspection, testing, and maintenance of fuel gas detection and warning equipment in buildings and structures. Additionally, the Fire Protection Research Foundation, the research affiliate of NFPA, recently released a report on combustible gas detection (CGD) placement. The research looks to use modeling work to justify requirements in NFPA 715 for the best location of CGD in order to ensure early and accurate detection of leaks. The Research Foundation hosted a webinar on the topic earlier this month too.

For more information on odorant fade, check out the fact sheet here.


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Kyle Etter
Kyle Etter
Public Affairs Intern

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