GARDEN GROVE, Calif. - The day before his 41st birthday, Hernando Morales found himself hurrying his one-year-old into the backseat of his car when an industrial tank just over a mile away from his apartment threatened to explode and release toxic chemicals throughout the area. Five days later, local officials said it was safe and his family was allowed to return to Garden Grove.
"Thank God we are able to now be back home," Morales said in Spanish on Wednesday, while driving by the GKN Aerospace plant where the tank is located. Multiple nights sleeping with his family in the car and days at a friend's home took a toll, he said. "We finally got to rest last night." But that doesn't ease the long-term concerns of people in Orange County about the aircraft components manufacturer.
Morales was one of about 50,000 people forced to evacuate after as much as 7,000 gallons of methyl methacrylate overheated inside of a tank and became liable to explode ahead of Memorial Day weekend. The chemical, which is used to make plastics, has a low boiling point and the resulting gas increased pressure inside the tank to dangerous levels. The nearly week-long crisis sent thousands, including the Morales family, scrambling to pick up what possessions they could and flee their homes to nearby shelters. Today, many are left wondering how concerned they should be for their health.
Orange County health officials said Tuesday there were no chemical leaks from the tank and it no longer posed a risk to the public. Air monitors around the facility did not detect methyl methacrylate or volatile organic compounds, according to the U.S. Environmental Protection Agency. Nonetheless, families question how safe the area is.
Andrew Whelton, a professor at the Lyles School of Civil and Construction Engineering at Purdue University, said he understood concerns from residents given the few details released by the county and federal officials over how exactly testing was conducted and what results were found around the site. "To me, it doesn't make sense that there was absolutely no chemical release from the tank," Whelton told Inside Climate News on Wednesday. "If you have a pressurized soda can and you pop a hole in it, something will come out."
The EPA deployed photoionization detectors, or PIDs, as the "primary sensor" for detecting methyl methacrylate and other possibly concerning chemicals around the GKN Aerospace facility and in the surrounding community. Those monitors showed "no exceedances," the EPA said. The South Coast Air Quality Management District said it deployed a mobile air monitoring unit to the perimeter of the evacuation zone six times between May 21 and May 22, which showed "typical background levels." Neither agency provided detailed air test results.
The use of PID sensors to let residents know the air was safe after the six-day crisis could be worrisome, Whelton said. "There's a waterfall of evidence showing PID-only testing for emergencies and disasters isn't health protective," he said. In February 2023, a train derailment, chemical spill and fire in East Palestine, Ohio, released contaminants into the air, soil, waterways and buildings. Afterward, Whelton developed a rapid-response study and found that business owners and others who conducted their own commercial lab tests discovered chemicals in buildings that PIDs never detected.
Ronald Fritzgerald, a veteran with the U.S. Army Corps of Engineers, was among the dozens at a Fountain Valley shelter. His home in Stanton was in the zone marked red on a map identifying the areas most at risk in the event of a potential blast, but he never knew GKN Aerospace ran a plant about a mile from where he lived. "Everything I own is in my apartment," the 76-year-old said from the motorized scooter he uses to get around. "I literally escaped with just the shirt on my back."
Francisco Lopez and Irma Ramirez were happy to get back into their home on Tuesday, but said planning for the long term around the tank is not easy. Police and local officials had warned the couple ahead of the Memorial Day weekend that the blast from the tank could be so strong it could release chemicals into their neighborhood and have enough force to shatter their windows. Despite his ongoing concerns, "for now we're staying here," Lopez, 50, said in Spanish, noting how much moving can cost. "We don't have anywhere else to go."
The U.K. company was cited by the South Coast Air Quality Management District last year for several violations and penalized $900,000. Those included the company using more chemicals for manufacturing than its permits allowed, letting chemical emissions exceed the legal limits and mismanagement of records and permitting. The Orange County Environmental Health Division most recently inspected the GKN Aerospace facility in 2024 and cited it for five violations related to labeling and managing hazardous waste, training issues and for not properly accounting for waste. OSHA has inspected GKN Aerospace facilities more than a dozen times since 2018 and given the company at least nine citations.
Almost 15 percent of incidents in the nation involving uncontrolled chemical reactions between 1980 and 2001 were polymerization thermal runaways like the one that threatened the GKN Aerospace tank, according to a study.