OMAHA, Neb. — A new federal rule finalized Monday aims to ensure that first responders can find out what hazardous chemicals are on a train almost immediately after a derailment so they can respond appropriately.

Too often in past disasters like last year’s fiery Norfolk Southern derailment in East Palestine, Ohio, firefighters risked their lives trying to extinguish a blaze without knowing the right way to respond. The local fire chief in charge of the response said it took him 45 minutes to learn exactly what was in the 11 burning tank cars on the train, but some firefighters from neighboring departments who came to help said they didn’t know what they were dealing with until two hours after the Feb. 3, 2023, crash.

First responders need to know exactly which hazardous materials are on a train so they can look it up in the government’s official guidebook and make sure they have the right protective gear and firefighting tools, said Tristan Brown, deputy administrator of the Pipelines and Hazardous Materials Safety Administration agency that proposed the rule.

Knowing what chemical is involved and how much of it is aboard also affects how big of an evacuation zone might be required to protect the public.

“There are so many different types of hazardous materials being transported across the country on any given day — 1 in 10 goods that move across the United States — and each one poses unique risks and hazards, certainly to the folks who are running towards a fire,” Brown said. “But certainly as well for anybody who may be living or working in that vicinity.”

The rule was published just one day ahead of the National Transportation Safety Board’s final hearing on the East Palestine derailment, where they will discuss exactly what caused that crash and recommend steps to prevent similar disasters.

Train crews have long carried lists of their cargo in the cabs of their locomotives, but in the middle of the chaos after a derailment those engineers and conductors, who might have moved their locomotives miles down the track, can’t always be found right away.

That’s part of why the largest freight railroads developed an app called AskRail roughly a decade ago that enables firefighters to quickly look up the details of what each train carries. But not every firefighter had the app, and cellphones don’t always have a signal strong enough to work in a disaster.

Regulators want the railroads to continue expanding access to that app, including to 911 centers, so information reaches first responders sooner.

The six biggest railroads also make train cargo information immediately available through the chemical industry’s hazardous materials hotlines in the U.S. and Canada.

But the new federal rule also applies to the hundreds of smaller railroads that aren’t involved in AskRail. Even railroads that only have one or two employees now must have a plan to quickly get the crucial details of their cargo to the local fire department, even if it’s as simple as having the fire chief’s cellphone number at the ready.