Exposure to methyl methacrylate, a highly flammable chemical used to make plastics, can cause serious respiratory and neurological problems.
GARDEN GROVE, Calif. — Thousands of Southern California residents remained unable to return home Tuesday as crews worked to cool damaged homes. Storage tanks containing hazardous chemicals at an aerospace plant, despite officials saying there catastrophic explosion It’s basically over.
“This is not over yet,” Orange County Fire Department interim fire chief TJ McGovern said Monday. “We still have to mitigate concerns about fires and very small explosions, as well as the possibility of leaks.”
On Thursday, officials began ordering residents in Garden Grove, near Los Angeles, to evacuate their homes after water tanks overheated. About 16,000 residents among 50,000 evacuees are still waiting for the warning to be lifted.
According to reports, exposure to methyl methacrylate, a highly flammable chemical used to make plastics, can cause serious respiratory problems, neurological problems and irritation to the skin, eyes and throat. federal environmental protection agency. Tanks at the GKN Aerospace Transparency Systems facility contain 6,000 to 7,000 gallons of chemicals.
An assessment of the tank showed internal pressure had been reduced due to the crack discovered Sunday. Craig Covey, chief of the county’s fire department, said Monday that the temperature inside had dropped to 93 degrees Fahrenheit (33.9 degrees Celsius), down from 100 degrees Fahrenheit (37.7 degrees Celsius) a day earlier. The company said its technical experts and the county fire marshal removed the tank’s insulation to aid cooling.
Health officials tried to reassure people who had returned to their homes near the factory.
“There’s no contamination. There’s no smoke. There’s no vapor from this incident,” Orange County Health Department Director Regina Chinsio-Kwong said at a news conference Monday. “There’s no leak. So that should be it, even if you’re across the street from the new zone line, you should be able to go home feeling safe.”
Orange County Supervisor Janet Nguyen said the South Coast Air Quality Management District will monitor air quality for months and the Environmental Protection Agency will check sewers and storm drains for leaks.
Resident relief
Kim Yen, a retiree who had to evacuate her home two blocks from the factory, said she was ready to go back but first needed to make sure she was safe.
“I’m happy, and a lot of us are happy, but we’re still evacuating,” she said Monday.
The parking lot at a large park in Fountain Valley southwest of Garden Grove was full Monday as people sought shelter in makeshift shelters there or pitched tents outside. Others gathered in the park to celebrate Memorial Day.
Yan added that she has been worried about emergency responders.
“They truly are our heroes,” she said.
Environmental risks remain
Andrew Whelton, an engineering professor at Purdue University who studies environmental pollution, said as the tanks heat up, the chemicals convert from liquids to gases, increasing pressure and the risk of explosions. Some of the methyl methacrylate may have hardened into a stable plastic similar to Plexiglas, reducing the hazard, he said.
Whelton said the tank could eventually cool enough for crews to safely stabilize and drain the remaining material without causing a spark or ignition.
However, he said there is still a risk of explosion when the chemicals are still hot and reactive. He said temperatures would need to drop closer to 60 to 70 degrees Fahrenheit (15.6 to 21.1 degrees Celsius) before conditions would be considered significantly safe.
GKN is a British company that supplies aircraft manufacturers
GKN Aerospace Transparent Systems manufactures cockpit windows, canopies and windshields for military and commercial aircraft. The company has about 16,000 employees at 32 production sites in 12 countries, according to its website.
“We apologize for the ongoing disruption caused by this incident and our priority remains to resolve the issue safely so residents can return to their homes as quickly as possible,” the company said.
GKN Aerospace agreed in 2025 to pay state regulators more than $900,000 to resolve violations involving recordkeeping, permitting issues and nitrogen oxide emissions, according to a report on the South Coast Air Quality Management District’s website.
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