Even the most hazmat-phobic firefighter understands that chemical agents are added to odorless natural gas to make it obvious when there’s a leak. Beyond that baseline of basic knowledge, firefighter understanding of how odor agents work and how to detect the danger behind the smell can be all over the map.
Refresher courses for safety
Whether it is teaching hazmat to new cadets, conducting annual refresher courses, or leading a team of firefighters into hazmat scenarios, having them up to speed on this topic is key to everyone’s safety.
Many associate the National Institute for Occupational Safety and Health with their firefighter line-of-duty death investigations and the subsequent reports. Yet this branch of the Center for Disease Control does a lot more in the field of fire research and education.
Safety Advisory on odor fade
Anosmia, hyposomia, and nasal inflammation can interfere with the ability to smell mercaptan
NIOSH recently issued a two-page Safety Advisory on odor fade in natural and propane gases. This is a great handout and springboard into this topic for the next hazmat class. It is critical to teach or remind firefighters that the methyl mercaptan in natural gas and the ethyl mercaptan in propane are not reliable indicators of the presence of either gas.
The first, and most timely, reason is that sense of smell is not reliable. Anosmia (inability to smell), hyposomia (reduced sense of smell), and nasal inflammation can interfere with the ability to smell mercaptan. Due to COVID-19, these conditions are not the outliers they once were. Loss of smell is a main symptom of COVID-19.
Unreliable smell
Nature reports that one study shows that 96% of those with COVID-19 had some olfactory dysfunction. And many who have recovered from the disease report lingering effects a year after they’ve recovered, including odors being warped and unpleasant.
Even when a person’s sense of smell is functioning properly, there’s still a reason not to trust mercaptan. And if the firefighter is wearing SCBA, the sense of smell is moot. If the firefighter is not, it can be too late by the time he smells the substance.
Odorant effectiveness
Newer transport and storage systems will essentially suck the mercaptan out of the gas, absorbing it
Much like freshly poured concrete or a cast iron skillet, pipelines and storage tanks need time to cure. Newer transport and storage systems will essentially suck the mercaptan out of the gas, absorbing it.
This, of course, diminishes the odor agent’s quantity and effectiveness. The Safety Alert says this is especially true for large-diameter steel pipes and tanks, but it can also happen in smaller-diameter polyethylene lines.
importance of testing
The odorant can also be absorbed through materials it comes in contact with while leaking. This can include plywood, drywall, soil, and concrete. Of course, this reinforces the need to aggressively teach what is already known, that the senses alone cannot be trusted when it comes to hazmat.
It means hammering home the importance of testing with a meter. It means ensuring that those meters are properly maintained, powered, and calibrated. It also means that firefighters must be as comfortable with using a meter as they are with a halligan.
They need to be confident with the meter when the stress level is high and conversely not complacent about testing when the call seems routine. And they need to be confident that they can trust the meter and know when they can’t trust it. This goes back to hands-on training.
HazSim Pro Gas Monitoring Training
Simulation technology, like HazSim, is the key to real hands-on experience where students can see meter readings change in real-time. So, one drill using HazSim would be to set up a perimeter on a gas leak.
The student must show proficiency with proper search techniques, scanning high and low, and using the readings to accurately draw the perimeter lines, recommend evacuation or shelter in place, and remove ignition sources. This NIOSH Safety Advisory is a great starting tool to train or re-train firefighters for hazmat calls.
