Augustin Guibaud ,

Ph.D.

A decade of New York City fire data shows that citywide trends can mask sharply different realities on the ground, with some neighborhoods moving in the opposite direction of the city as a whole.

A new study published in the Fire Safety Journal breaks down more than 411,000 structural fire incidents recorded by the FDNY between 2013 and 2023 across roughly 2,200 census tracts, small statistical subdivisions of a few thousand residents each, rather than the borough- or citywide figures typically used to track fire trends.

Hannah Bonestroo, a Ph.D. student in Urban Systems at NYU Tandon School of Engineering, conducted the research with Assistant Professor Augustin Guibaud, a faculty member of the Department of Mechanical and Aerospace Engineering affiliated with the NYU Tandon’s Center for Urban Science + Progress.

"If the city is looking at inequalities at the neighborhood scale, or allocating resources at the neighborhood scale, there may be areas with different patterns that get missed," said Bonestroo.

At the citywide level, the story looked simple. Structural fires fell 11.3 percent over the decade, a clear improvement. But that average hid real variation underneath it.

"If you look much more granularly at the census tract level, there were hot spots, areas where fires were actually increasing over the ten years,” said Bonestroo. Eastern Queens and Staten Island were among the places moving against the citywide trend.

Response time showed a different pattern entirely, forming large clusters of similar trends across the city rather than concentrating in pockets. Average response time rose 30 seconds over the decade, from 4 minutes 6 seconds to 4 minutes 36 seconds, now exceeding the National Fire Protection Association's 4-minute travel-time standard.

"In a fire, every second counts," said Guibaud. "Thirty seconds may not sound like much, but it can be enough time for a fire to intensify and for smoke to fill a space, and the first crew on scene can arrive to a situation that's already beyond what they can handle."

"Almost the entire city is following the pattern of it increasing," Bonestroo said, a contrast to fire frequency, which varied sharply block to block. Northwestern Queens saw the sharpest deterioration in response time over the decade.

Recent reviews by the FDNY and the New York State Senate have pointed to traffic congestion and rising call volume – the department responds to more than a million emergency calls a year – rather than neighborhood demographics or distance from firehouses. The researchers' analysis agrees, as fixed socioeconomic and built-environment factors explained only about a quarter of the differences in response time between tracts.

That contrast pointed to a second finding. Fire frequency and response time capture largely different dimensions of risk. Areas with the most fires tended to have faster response times, not slower, something Bonestroo reads as reassuring rather than puzzling.

 "That's a good indicator that FDNY has placed its resources where the fires are," Bonestroo said.

Because the two measures move independently, Bonestroo and Guibaud built a Dual Risk Index, designed to catch tracts that don't top the list on fire count or response time individually, but rank high on both at once. To put it simple, fire frequency reflects the likelihood of a fire. Response time shapes how bad it can get once one starts. The index multiplies the two.

 "If you just looked at the top 50 tracts by number of fires, you might miss a tract that has a fairly high number of fires and fairly slow response time, just not the highest number and the slowest time," Bonestroo said. "That's the kind of area the index is meant to catch."

Mapped across the city, high dual-risk areas cluster in Manhattan, the Bronx, and at the city's periphery, while central Brooklyn and Queens score lowest.

Tested against the locations of multi-alarm fires, the most severe incidents, over the decade, the index performed modestly better than either individual measure at flagging high-priority tracts. None of the measures, including the index, strongly pinpointed where the city's most severe fires occurred.

"It showed that it did capture more, but it wasn't statistically significant once you account for the confidence intervals," Bonestroo said.

The researchers say that shows the need for better public data on fire outcomes. "The paper isn't meant to tell FDNY where they need to reallocate resources," Bonestroo added. "Rather, it’s meant to reveal neighborhoods that may not be following overall citywide trends and are worthy of further inquiry to understand why." The index is a starting point, as the researchers plan to test other ways of accounting for other factors such as overall building safety records.

The analysis relies entirely on public data: FDNY's Fire Incident Dispatch Data and NYFIRS, the federal NFIRS system (replaced by a new national reporting system, NERIS, in February 2026), the Mayor's Management Report, and U.S. Census Bureau estimates. “Unfortunately, these sources vary in their reporting, even though records are meant to pass between the systems unchanged, so even the most basic count depends on which record you consulted” said Guibaud.

For 2023, the city's official tally in the Mayor's Management Report lists 35,567 fires, against 30,301 for the federal NFIRS database records, some 5,300 fewer. Individual incidents were sometimes classified differently from one dataset to the next, and Bonestroo carefully mapped the discrepancy by identifying where individual fire event landed in each database.

Bonestroo received a Sheldon Tieszen Student Award in June 2026 at the International Symposium on Fire Safety Science in La Rochelle, France, for the paper.

Bonestroo, H., & Augustin, G. (2026). Structural fires and emergency response in New York City: A spatiotemporal analysis of fire incidence and severity. Fire Safety Journal, 162, 104718. https://doi.org/10.1016/j.firesaf.2026.104718

Hydrogen is often touted as a clean, carbon-free energy carrier that could help decarbonize industry and transportation. Yet the very properties that make it efficient and lightweight also make it uniquely tricky to handle safely. A new study published in the International Journal of Hydrogen Energy by researchers at NYU Tandon and University College London takes a systematic look at what truly makes hydrogen accidents different from conventional industrial failures, and what that means for safety and regulation.

By analyzing more than 700 incidents in the Hydrogen Incidents and Accidents Database (HIAD 2.0), the team found that 59 percent of mishaps involving hydrogen stem from the same sorts of issues that plague other energy systems: design flaws, mechanical failures, and human error. Only 15 percent can be directly traced to the intrinsic properties of hydrogen itself, such as its high diffusivity, low ignition energy, or ability to degrade metals from within. The remaining cases lacked enough detail to tell one way or another.

“Of course, in the case of hydrogen, the consequences of a fire or an explosion can be a lot more severe due to the unique combustion properties of this gas. But when looking at the root cause of an incident, hydrogen is not inherently more dangerous than other flammable gases used in industry,” says lead author Augustin Guibaud, Assistant Professor of Mechanical and Aerospace Engineering. “However, the way it interacts with materials and the environment is fundamentally different. The danger comes from misunderstanding those differences.”

Those differences arise from hydrogen’s atomic scale. Its extremely small molecules slip through metal lattices where larger gases like methane cannot, leading to subtle but serious material failures. The study details several such mechanisms: hydrogen embrittlement, which weakens metals by disrupting atomic bonds; hydrogen-induced cracking, in which pressurized gas accumulates inside tiny voids until the material bursts; and high-temperature hydrogen attack, where hydrogen reacts with carbon in steel to form methane, eroding its structure. Other hazards include hydrogen-assisted corrosion and the effects of storing the gas at pressures up to 700 bar — dozens of times higher than those used for natural gas.

These microscopic processes have huge consequences. The 2019 explosion at a hydrogen refueling station in Sandvika, Norway, for example, stemmed from a faulty high-pressure component rather than combustion chemistry, but it underscored how even small mechanical flaws can escalate quickly under hydrogen service conditions.

Guibaud, who is also a member of the Center for Urban Science + Progress, notes that the goal of the research is not to minimize hydrogen’s risks but to clarify them. “Our findings also highlight where traditional safety practices fail to capture hydrogen’s unique behavior,” Guibaud says. “If we can distinguish between what is general and what is hydrogen-specific, we can focus regulation and design standards on the right problems.”

That distinction, the authors argue, is essential as hydrogen infrastructure expands beyond controlled industrial sites into urban fueling stations, residential heating, and renewable power storage. Current regulations, they point out, often apply “one-size-fits-all” safety distances or design codes that lack a strong scientific basis. Overly cautious rules can slow deployment and raise costs, while overly permissive ones can leave gaps in protection.

Instead, the researchers advocate for risk-informed, evidence-based safety standards grounded in hydrogen’s particular chemistry and physics. They also call for improved data collection and international coordination, noting that the hydrogen industry today lacks the tools to improve systematic data collection and transparency.

“The challenge,” says Guibaud, “isn’t just preventing accidents — it’s learning from them fast enough to guide a rapidly changing energy landscape.” As hydrogen moves from the lab to the mainstream, knowing which failures are truly “hydrogen failures” may prove as vital as the technology itself.

Li, Yutao, et al. “Differentiating hydrogen-driven hazards from conventional failure modes in hydrogen infrastructure.” International Journal of Hydrogen Energy, vol. 183, Oct. 2025, p. 151155, https://doi.org/10.1016/j.ijhydene.2025.151155.