By Frank Leeb
This article is republished with permission from CRACKYL Magazine
This common danger injures civilians and firefighters alike, showing why every odor of gas must be treated as a major threat
Shortly after midnight on Saturday, Jan. 24, 2026, FDNY units responded to a reported gas odor in a high-rise residential building in the Bronx. Shortly after arrival, while investigating the odor, an explosion occurred. Fourteen people were injured, one civilian was killed, and the resulting fire required a fourth-alarm response to control. Two floors of the 17-story building were heavily involved. What began as one of the most common FDNY responses, an odor of gas investigation, rapidly escalated into a major fire with tragic consequences.
On Sept. 27, 2016, also in the Bronx, the FDNY responded to another odor of gas. During operations, an explosion occurred, killing Battalion Chief Michael Fahy of Battalion 19. At the time of the explosion, Chief Fahy was commanding operations from the street when the two-story private dwelling detonated. That line-of-duty death led to a comprehensive rewrite of FDNY procedures for operating at gas leaks.
Training Drill: Propane Leak in a Residence
More recently, on Oct. 10, 2025, again in the Bronx, a 20-story residential building was badly damaged by a natural gas explosion, requiring a major FDNY response (a 10-60).
Different years: 2016, 2025, 2026
Different structures.
Same hazard.
Why Natural Gas Incidents Escalate
These incidents underscore the extreme danger posed by natural gas when it accumulates in confined or poorly ventilated spaces. For firefighters, they represent a reminder to continually train on the properties, hazards, and procedures associated with natural gas emergencies, one of the FDNY’s most frequent responses. The odor of gas.
Natural gas is lighter than air and has an explosive range between approximately 5% and 15%. When gas within that range ignites in a confined space, the result is an explosion, often with devastating force. When not confined, such as outdoors or in well-ventilated areas, gas will typically ignite rather than explode. Even then, firefighters must remain alert to areas where gas can accumulate.
Firefighters must be prepared to operate. Full PPE must be worn. Apparatus should not be positioned in areas that could quickly become hazardous zones. Often, the front of the structure is the worst place to be. Collapse zones, potential ignition sources, and areas where gas can migrate or accumulate must all be considered during size-up.
Understanding the Role of Odorants
Natural gas is composed primarily of methane, which in its natural state is colorless, odorless, and tasteless. Without modification, humans would have no reliable way to detect a leak before conditions became deadly. That is why an odorant, mercaptan, is added.
Mercaptan produces the familiar “rotten egg” or sulfur-like smell associated with gas leaks. It is added specifically to provide early warning of a gas leak. This practice began in the early 20th century following catastrophic explosions, most notably the 1937 New London School explosion in Texas (March 18, 1937), which killed 295 students and teachers. That tragedy led to mandatory odorization of natural gas.
Mercaptan has saved countless lives, but it is not foolproof. Firefighters must always verify conditions using combustible gas detectors.
The Limits of Relying on Odor
Relying on odor alone is dangerous.
Mercaptans can be stripped from natural gas as it migrates through soil, which can occur through underground leaks. Some individuals have a diminished ability to smell the odorant, while others become desensitized after prolonged exposure. Competing odors, such as from garbage or cooking, can also mask its presence.
Gas can also migrate into void spaces such as utility chases, walls, and elevator shafts, where an odor may not be immediately noticeable. By the time the smell is detected, concentrations may already be within the flammable range.
Once gas reaches that 5–15% window, all that is missing is an ignition source, and ignition sources are everywhere: light switches, elevators, HVAC systems, doorbells, pilot lights, static electricity, and even our own equipment.
When confined, it explodes, and the results can cause immediate structural failure, blowing out walls, collapsing floors, and endangering anyone operating inside or nearby.
Every odor of gas response must be treated as a high-risk operation until proven otherwise. This demands disciplined size-up, strict control of ignition sources, coordinated ventilation, proper use of PPE, and continuous meter use.
Respecting a Common but Deadly Hazard
Natural gas is part of everyday life and a frequent cause of emergency responses, which makes it easy to underestimate. The Bronx has repeatedly shown us the danger of this everyday hazard.
An odor of gas is never a minor response. Respect the hazard.
Control the environment.
Be ready to work.
Know your meters and use them.
