Fire officials near a Garden Grove aerospace facility stared down two potentially bad outcomes over Memorial Day weekend: Either an industrial tank could explode, or it could unleash large amounts of a toxic chemical into the air. 

For many, it was the first time they’d ever heard of the chemical – methyl methacrylate – and its potential consequences: respiratory issues, nosebleeds, nausea and skin reactions that could lead to hospitalization. 

The Orange County Fire Authority narrowly avoided a disaster when the tank cracked just enough to relieve the pressure. Gov. Gavin Newsom declared a state of emergency, and multiple agencies are now investigating what happened. But the danger remains for some.

A CalMatters review of federal data from the Environmental Protection Agency found 14 facilities stored methyl methacrylate in California in 2024. That year, four of them stored amounts that are similar to or greater than the amount that nearly caused a disaster near the GKN Aerospace facility in Garden Grove. 

Community advocates say the Garden Grove emergency illustrates how gaps in regulation and weak oversight allow dangerous chemicals to threaten the lives and property of thousands of people. 

“This could happen anywhere,” said Ivana Castellanos, toxics program manager with Physicians for Social Responsibility Los Angeles. “There’s so many facilities that have toxic chemicals … and it’s very easy for (something) to go wrong.” 

At GKN Aerospace, methyl methacrylate was stored in a tank as a liquid. Exposed to heat, that liquid can trigger a chemical reaction called “thermal runaway” in which the substance heats until it becomes highly flammable and even explosive. Federal data from 2024 shows the company stored from 100,000 to just under 1 million pounds of the toxic chemical.

Several of the other companies that also told federal regulators they stored the chemical have facilities near where people live. Three facilities stored far greater amounts of 1 million to 10 million pounds each:  Rohm & Haas Chemicals in Hayward, Engineered Polymer Solutions in Commerce and Plaskolite West in Compton. A fifth facility, Arkema Coating Resins Plant in Torrance, stored similar amounts to GKN Aerospace.  

Methyl methacrylate is not a regulated substance under either the U.S. Environmental Protection Agency’s Risk Management Program or California’s parallel system, known as CalARP. In some places, process safety rules that protect workers may cause agencies to scrutinize the chemical. Facilities may still have to have fire or other emergency plans. But facilities holding chemicals that fall outside federal and state accident prevention programs may not have to participate in community emergency planning or drills. 

Plaskolite West in Compton stores up to 20,000 pounds of methyl methacrylate in tanks and under 2 million pounds in rail cars, said Roger Hamilton, the company’s vice president of operations. While it’s stored, the chemical is treated with an inhibiting agent to prevent a runaway reaction, he said.

Hamilton said the company reviews its internal emergency plans annually, and the Orange County incident has prompted another review. The plans include how to respond to spills, train operators and monitor the chemicals. 

The company has received five violation notices from the South Coast Air Quality Management District since 2003. Regulators cited the company for failing to follow permit conditions for certain equipment in 2021,  and in 2022, South Coast accused the company of creating a public nuisance after the chemical was released into the air. 

Hamilton said the latter incident happened when a nylon bag carrying the methyl methacrylate broke, releasing a strong odor into the air. He said he was unaware of the earlier incident.  

“Anytime you’re dealing with any kind of substrates or materials of any hazardous substance, there’s always risk associated with it,” he said. “We try to be very safety conscious when we’re handling this stuff, not only just for our employees, but for the communities around us, and we try to follow all the state and federal laws.” 

Glynna Mayers, a representative for Rohm & Haas Chemicals, said the site currently stores less than 1 million pounds of the material and follows all applicable storage and handling requirements. 

In Hayward, Mayers said, the company stores the chemical in an above-ground tank surrounded by concrete, protected by a fire suppression system. Like Plaskolite West, it uses a chemical inhibitor to prevent the methyl methacrylate from reacting. The company also conducts regular drills with local emergency responders, she said. 

“Our priority remains the safety and security of our employees, neighbors, and the environment,” Mayers said. 

Dave Schrader, a representative for the Arkema Coating Resins facility, said the company is reviewing what it can learn from the Garden Grove incident. He said the Torrance facility has a strong record of safety and environmental compliance. 

“Arkema and the Torrance facility are vigilant about safety and environmental compliance, which is reflected in the facility’s strong performance in these areas,” Schrader said. “The facility conducts regular emergency response drills with its own teams multiple times a year and with local emergency responders at least once a year to ensure the site is prepared in the unlikely event of an emergency,” Schrader said.

Engineered Polymer Solutions, which stores between 1 million and 10 million pounds of methyl methacrylate, didn’t respond to calls and emails from CalMatters by deadline.

The Garden Grove emergency caught environmental advocates off guard in one way — few had heard of methyl methacrylate. But how the disaster unfolded was a familiar story. 

GKN Aerospace agreed to pay more than $900,000 to settle a number of violations from the South Coast air district in an agreement signed in 2024. The district continued issuing the facility permits as part of its expansion plans. 

“Systemically, government agencies … continue to allow companies to operate with inadequate safeguards, in some cases without permits, in some cases even issuing new permits despite decades of violations,” said Bradley Angel, director of Greenaction for Health and Environmental Justice. “This is business as usual.” 

All five facilities are located in communities ranked among the top 50% of the most environmentally burdened communities in the state, according to CalEnviroScreen 5.0. The Compton and the Commerce facilities ranked highest, both in the top 10%. 

Cynthia Babich, executive director of the Del Amo Action Committee, said she had no idea a facility handling methyl methacrylate operated so close to residents.

Without stronger regulations and public emergency plans for how to handle a disaster, she doesn’t think residents are safe. 

“When things like what happened in Orange County happen, it just underlines all the fears that our community has – that people are not prepared and we’re not being protected, and they have really dangerous chemicals in our community,” Babich said.

Alejandro Lazo contributed to this report.