EV fire research: Firefighters should use water, not blankets, experts say

November 8, 2025 — As electric vehicles (EVs) become more common on U.S. roads, fire departments are grappling with a new challenge: how to safely and effectively respond to EV fires. Contrary to popular belief, a landmark three-year study from UL Research Institutes’ Fire Safety Research Institute (FSRI) shows that EV fires behave much like conventional gasoline vehicle fires — and that the best tactic is often the simplest: water.

Adam Barowy, Principal Research Engineer at FSRI, shared the institute’s findings with The Innovation Platform, offering clear guidance for fire crews and EV owners alike. The research, which involved 18 full-scale vehicle burns (nine without suppression, nine with various tactics), directly addresses questions about fire growth, suppression effectiveness, and chemical exposure.

“Our data from the free-burn experiments showed that EV and ICEV fires demonstrated similar fire growth rate, peak fire size, and fire duration,” Barowy said. “The cabin — containing plastics, foam, and ordinary combustibles — is the biggest fuel driver in vehicle fires, and cabin design is very similar between EVs and internal combustion engine vehicles (ICEVs).”

Key takeaways for firefighters

The study’s most actionable findings include four core recommendations:

• Expect similar fire behavior. EV fires are not inherently faster, bigger, or longer-lasting than gasoline vehicle fires. In free-burn tests without intervention, both types burned out within 90 minutes.
• Use water to control the cabin fire and protect exposures. Water effectively suppresses the passenger compartment fire and can cool nearby exposures. However, it cannot stop thermal runaway inside the battery pack once started.
• Use fire blankets with caution. FSRI found that blankets can extinguish cabin fires, but thermal runaway continues inside the battery. If flammable gases accumulate under the blanket — especially in confined spaces like parking garages — an explosion hazard exists.
• Stay in full PPE and SCBA throughout the incident. All vehicle fires produce hazardous smoke, but EV fires emit elevated levels of metals and particulate fluoride. The long-term health effects are not fully understood, but contaminants from all vehicle fires are known to have negative health impacts.

Why water works — and why special tools aren’t needed

One of the study’s most reassuring conclusions is that fire departments do not need to invest in expensive, specialized equipment. “For fire departments, this is good news. They are generally able to meet the hazards of EV fires with tactics they already know and have practiced,” Barowy emphasized.

The reason water cannot stop thermal runaway is simple: battery enclosures are designed to be water-resistant. “Water can’t reach the battery and therefore using large amounts of water to cool the battery and interrupt thermal runaway is ineffective,” Barowy explained. Even water additives didn’t outperform plain water.

Data from the Dutch fire service — which tracks EV incidents closely — shows that the majority of EV fire incidents do not involve the battery at all. This reinforces the strategy of using water to control the incident and letting the battery burn out safely.

Fire blankets: a double-edged sword

FSRI’s evaluation of EV fire blankets, which have become a popular suppression tool, revealed significant risks. While blankets can stop visible flaming and put out the cabin fire, the battery continues to undergo thermal runaway. The gases released — hydrogen, carbon monoxide, and other flammable compounds — can build up under the blanket and create an explosion hazard.

“Our team observed an explosion hazard if the flammable gases accumulate under the blanket or if the fire blanket is used in a confined operating environment like a parking garage,” Barowy noted. This is a critical warning for fire departments that may be tempted to rely on blankets as a primary tactic.

Exposure risks: new data on fluoride and metals

The research also measured contaminants in smoke, runoff water, and contaminated turnout gear. While all vehicle fires produce toxic smoke, EV fires showed notably higher concentrations of fluoride compounds and certain metals. These are associated with the battery chemistry and thermal decomposition.

“The full impact on human health is not fully known, but contaminants from all vehicle fires are known to have negative health effects,” Barowy said. Firefighters must remain in full PPE and SCBA even after the visible fire is out, because sudden reignition is possible — even days or weeks later.

Implications for fireground operations

Based on the findings, FSRI recommends the following operational adjustments:

• Prioritize life safety first, then control the cabin fire.
• Apply water to the cabin and exposures. Once the cabin fire is suppressed, continue to apply water to prevent reignition while the battery burns out.
• Coordinate with second responders (tow operators, salvage crews) to anticipate reignition. “We recommend that the fire service escort the tow truck with a suppression unit in case of reignition,” Barowy said.
• Treat EVs like any other fuel source. “Once they understand how the fuel behaves, they can be prepared to respond to incidents of all types.”

Advice for EV owners

Barowy also offered guidance for EV owners to reduce fire risk. “Generally, EVs are going to be safe. They have been tested against rigorous safety standards,” he said. Owners should follow manufacturer instructions for charging and maintenance. If involved in a collision, they should have the battery inspected for damage that could lead to a fire.

A growing body of evidence

The FSRI study is part of a broader effort to inform fire service best practices as EV adoption accelerates. The U.S. fire service currently lacks comprehensive national data on how many EV fires occur annually and how they unfold. Research from other countries, such as the Netherlands, provides valuable benchmarks.

“Our stakeholders in the fire service brought us questions about how to suppress fires that appeared at times to behave differently from those involving an ICEV,” Barowy recalled. The three-year study answers those questions with data, not anecdotes.

For fire departments across the United States, the message is clear: prepare for EV fires with the tools you already have — water, PPE, and situational awareness. Avoid untested gadgets and tactics that may introduce new hazards. And always plan for the unexpected, because a battery can reignite long after the flames are gone.

This article will also appear in the 27th edition of UL Research Institutes’ quarterly publication, Innovation Insights.