Hydrogen Fluoride at Refineries

Refineries store tens of thousands—often, hundreds of thousands—of pounds of HF on-site. If HF is released into the air from a refinery pipe or vessel at normal atmospheric conditions, its unique chemistry leads it to mix with moisture in the atmosphere, and form a dense, ground-hugging, toxic cloud that can travel for miles. About 19 million people live close enough to an HF refinery that they could become caught in such a deadly cloud. Many more live along the trucking and train routes that bring HF from its sole manufacturing facility in Louisiana to refineries all over the United States.   

In 1987, a release of at least 30,000 pounds of HF from a refinery in Texas sent more than 1,000 people to the hospital, many of whom went on to suffer long-term damage to their health. Since then, there have been more than 80 smaller-scale HF releases from the alkylation units at U.S. oil refineries. There have also been at least two near-miss events—in which a catastrophic explosion nearly released massive amounts of HF— in just the last decade. 

We submitted a petition to the U.S. Environmental Protection Agency (EPA) on February 11, 2025, under the Toxic Substances Control Act. This petition sets out the facts establishing why the EPA must issue regulations to eliminate the unreasonable risks to public health and the environment posed by the use of HF in domestic oil refining. We filed the petition with our partners: Clean Air Council and Communities for a Better Environment, groups dedicated to protecting people from pollution in the Mid-Atlantic and California, respectively.    

Some individual refineries—like the Trainer Refinery near Philadelphia and the ExxonMobil Joliet Refinery in Illinois—put more than a million people in danger of an HF release, according to the refineries’ own estimates. Many more—including refineries in Torrance and Wilmington, in LA County—leave hundreds of thousands of people in harm’s way. Critically, there’s no reason to leave so many people in danger. There are safer alternatives in use at most other refineries in the United States. Some refineries have even started or finished the process of converting away from HF to safer alternatives.   

On May 12, 2025, the EPA denied the petition. On July 8, 2025, NRDC, Clean Air Council (CAC), and Communities for a Better Environment (CBE) filed a lawsuit in federal district court asking the judge to rule that refinery use of hydrogen fluoride presents an unreasonable risk, which the EPA must eliminate through regulation. NRDC, CAC, and CBE filed their amended complaint in January 2026. In February 2026, EPA and Defendant-Intervenor Western States Petroleum Association filed motions to dismiss Plaintiffs’ amended complaint. Plaintiffs opposed. On June 10, 2026, the Parties presented oral argument on the  motions to dismiss before the U.S. District Court for the Central District of California. The district court granted the motions to dismiss but gave Plaintiffs leave to amend (that is, to revise and update) their amended complaint by July 22, 2026.

Under the Clean Air Act’s Risk Management Program (RMP), refineries that use HF for alkylation have to report basic information to the EPA every five years. RMP information is crucial for planning for and mitigating risk, including providing emergency response plans and advancing the facilities' accountability to maintain safeguards for employees and the public. The table below summarizes refinery owners’ submitted information for 43 U.S. refineries that (as of December 2024) use HF for alkylation, including refinery locations, an estimate of how much HF the refinery could release in a “worst-case” scenario, and the number of people living within the worst-case scenario zone who could encounter a poison cloud in case of such a release. More detailed information can be found for each refinery in the petition at appendix A.

In 1987, a refinery in Texas released a large cloud of toxic HF that injured more than 1,000 residents. HF is used in various industries, including by companies that refine petroleum through a process called alkylation. When exposed to moisture, HF is also called hydrofluoric acid (HA). The colorless chemical is extremely corrosive and dangerous to human health. NRDC has compiled, in the table below, recorded incidents from 1987 to the present at 42 of the U.S. refineries that have used HF for alkylation. These incidents encapsulate the continued risk of releases, explosions, and other dangerous failures at refineries that continue to use this chemical. Because not every release or other incident at refineries is recorded, this database is almost certainly an underestimate of this history.