Physicist Ronald Koopman attended the 2018 Southern California Air District conference and spoke about what seemed like an esoteric scientific topic: hydrofluoric acid dispersion and moisture reduction testing.
Hydrofluoric acid (also known as hydrogen fluoride or HF) is used to make a variety of materials, including refrigerants, gasoline, fluorinated pesticides, and fluoropolymers, such as those used to make Teflon. It is also one of the most corrosive and dangerous chemicals known. Koopman conducted experiments with the chemical in the 1980s and warned of the potential for fatal accidents in facilities using hazardous materials.
Mr. Koopman’s presentation on highly hazardous substances takes on new urgency as the Trump administration looks to roll back rules meant to protect workers and communities from releases of devastating industrial chemicals, and new analysis shows rising rates of chemical accidents.
The number of accidents involving the release of dangerous chemicals increased by 57% from 2021 to 2025, from 83 to 131, according to an analysis released Monday by Environmentally Responsible Public Employees, a nonprofit group that works with former government officials.
Over the same five-year period, the number of people injured or killed in accidents also increased from 60 to 89, according to the analysis. According to an accident report published by the Chemical Safety Board (CSB), an independent body that investigates chemical accidents, more than 650 accidents occurred between April 2020 and May 2026, of which 103 resulted in deaths, 355 resulted in injuries, and 314 resulted in “significant property damage.”
Nearly 150 million people live within three miles of these facilities. Historically underserved and overburdened populations, including those who identify as Black and Latino, are most at risk of being exposed to contingent release.
The analysis shows that many refineries were built before 1985. “The risk increases with each passing year because the infrastructure is aging,” said Jeff Ruch, senior advisor at PEER.
The 1980s HF experiment was conducted by Koopman, who now runs Hazard Analysis Consulting, on behalf of the oil company Amoco (later acquired by BP), to understand how highly toxic refinery chemicals behave in a spill.
Koopman told the air district conference that the experiment was a “remarkable success” in demonstrating what can happen and how serious the problem is. When they released 1,000 gallons of toxic chemicals, they expected it to settle in the ground and release small amounts of gas. Instead, a billowing, “ground-hugging” fog developed, allowing the deadly gas to travel miles downwind, much further than anyone had thought.
Years later, after a series of violent explosions at the Philadelphia Energy Solutions refinery’s hydrofluoric acid unit shook the South Philadelphia area in 2019, Koopman told NPR that it was “totally unconscionable” to allow people to live near these refineries.
The accident released more than 5,000 pounds of chemicals. Adjacent predominantly black and brown South Philadelphia neighborhoods were spared due to “favourable wind conditions,” the CSB said.
On June 21, 2019, a series of fires and explosions occurred after a heavily corroded pipe elbow ruptured at the Philadelphia Energy Solutions refinery in South Philadelphia. The accident released more than 5,000 pounds of highly toxic hydrofluoric acid, sent 38,000 pounds of equipment debris across the Schuylkill River, and caused an estimated $750 million in property damage.
“We tried and failed to get EPA to phase out hydrogen fluoride at these refineries,” Ruesch said. “Refineries are located near populated areas, and a gas release could be a truly horrifying tragedy.”
Exposure to 170 ppm hydrogen fluoride for 10 minutes can cause death or serious injury.
PEER petitioned the EPA to ban hydrogen fluoride in 2019 after the Philadelphia refinery’s massive explosion, but the EPA refused to consider the petition.
Nearly 50 refineries use hydrogen fluoride, and more than 200 incidents resulting in serious injury or death have been reported to the EPA over the past 25 years, according to the nonprofit Public Health Watch. These refineries are just a few of the 12,000 facilities that use certain hazardous substances and are regulated by EPA’s risk management program under the Clean Air Act.
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The new statistics released by PEER come as a result of a lawsuit brought by PEER and other groups to force the Chemical Safety Board to disclose industrial chemical releases as required by the Clean Air Act. A federal judge ruled in 2019 that communities have a right to know what dangerous chemicals are being released in their neighborhood.
But President Trump’s EPA last year removed a public data tool aimed at informing communities about the risks in their neighborhoods. President Trump is also seeking to abolish the Chemical Safety Board by withholding funding, even though Congress continues to fund it.
Earlier this year, the administration proposed significantly weakening the RMP rule, which will be finalized in 2024, “to reduce regulatory burden,” and was accepting public comments on the rule until early May.
The Biden administration’s enhanced RMP rules require a number of measures to reduce the risk of catastrophic accidents, including safer alternative analysis, independent analysis of the root causes of accidents, worker participation in accident prevention plans, and preparations to adapt to climate change.
An EPA spokesperson said the agency is considering public comments and continues to work toward finalizing the rule by the end of 2026.
“EPA’s proposal is based on a rigorous analysis of RMP reportable incidents from 2014 to 2023, which shows clear and significant reductions in accidental releases over this period,” the spokesperson said. “This means RMP-regulated facilities had adequate prevention programs in place before the Biden EPA finalized the pointless and burdensome 2024 rule.”
The Biden EPA used the same data but came to the opposite conclusion, PEER’s Ruesch said. He added, “The conclusion that any reduction is due to industrial prevention programs is hypothetical and EPA currently lacks supporting data.”
Meanwhile, chemical accidents that result in evacuation, injury, or multiple casualties continue to occur at least once a week.
“The risk increases with each passing year because the infrastructure is aging,” Ruesch said. At the same time, he added, “the federal government’s response to it is shrinking.”
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Lisa Gross is a reporter for Inside Climate News based in Northern California. She is the author of the Science Writer’s Handbook of Investigative Reporting and a contributor to the Science Writer’s Handbook. Both were funded by the National Science Writers Association’s Peggy Gershman Ideas Grant. She has covered science, conservation, agriculture, public and environmental health and justice for many years, with a focus on the misuse of science for private gain. Prior to joining ICN, he worked as a part-time journal editor for the open access journal PLOS Biology, a reporter for the Food & Environmental Reporting Network, and produced freelance articles for numerous national publications, including The New York Times, Washington Post, Discover, and Mother Jones. Her work has received awards from the Society of Healthcare Journalists, the American Society of Journalists and Authors, the Society of Professional Journalists NorCal, and the Society of Food Journalists.
