In Texas, which has long boasted of its culture of limited regulation, reaction to the agency’s statements was muted.

A spokesman for the Texas State Fire Marshal’s Office had no comment beyond noting that any change to state law would be an issue for the State Legislature. In West, where the Chemical Safety Board discussed its findings Tuesday, Mayor Tommy Muska pointed out that the plant was outside the city limits.

But he said there was a “huge gap” in the regulation of fertilizer plants, and supported Mr. Moure-Eraso’s recommendation that chemical manufacturers be required to use safer, less explosive blends of ammonium nitrate.

“It’s done in Europe,” Mr. Muska said. “If it doesn’t blow up, I don’t care where it’s stored.”

A spokeswoman for the E.P.A. said the Obama administration was working to improve the safety of chemical facilities. An executive order issued by President Obama in August established a working group to review federal chemical safety programs and make recommendations for improvements. “These efforts are already making a difference on the ground and will ensure that further progress is made in the near term,” said the spokeswoman, Alisha Johnson.

The explosion at the plant in West killed 14 people, wounded more than 200 others and destroyed or damaged hundreds of the town’s 700 homes. At 7:31 p.m. on April 17, 2013, the first 911 call came in about a fire at the plant. Twenty-two minutes later, at 7:53 p.m., after the fire intensified, an explosion ripped through the plant and the nearby residential neighborhoods, leaving a crater 93 feet wide and 10 feet deep. Between 40 to 60 tons of ammonium nitrate was kept in the warehouse, and 100 tons more was in a rail car adjacent to the plant, in addition to two large tanks of another chemical, anhydrous ammonia.

One year later, West, which is 20 miles north of Waco, continues to rebuild its housing and infrastructure. Ten of those who died were firefighters and emergency responders, including from the West Volunteer Fire Department; it was the largest number of firefighters to die in the line of duty in Texas at a single episode in nearly 70 years. Two of the four civilians who died were recognized by officials as honorary firefighters for responding to the scene.

At the time of the explosion, the guidance on fighting ammonium nitrate fires from chemical manufacturers, national fire codes and the federal government was vague and inconsistent, officials with the chemical safety agency said. “We do not take away from their heroism in the least by finding that they were not fully aware of the risk of an explosion,” Mr. Moure-Eraso said.

In July 2009, a fire erupted at an El Dorado Chemical Company plant filled with ammonium nitrate in Brazos County near Bryan, Tex., about 100 miles from West. The fire had a different outcome from the one in West: There was no explosion and no loss of life. Firefighters pulled back, let the plant burn for hours and evacuated thousands of people in nearby communities.