Emergency officials ended the evacuation for many residents near a damaged chemical tank in Southern California. This decision followed a decrease in temperature that removed the threat of a catastrophic explosion.
Although the risk of a major explosion at the GKN Aerospace Transparency Systems plant in Garden Grove has passed, there remains potential for smaller incidents like minor explosions or fires. Orange County Fire Authority division chief Craig Covey shared this update during a Monday press conference.
Reduction in Tank Pressure
An overnight review of the tank, containing 6,000 to 7,000 gallons (22,700 to 26,500 liters) of flammable methyl methacrylate, showed pressure had decreased due to a newly discovered crack. As a result, Covey reported that two-thirds of the evacuated residents, approximately 34,000 people, can return. He warned that dangers like fire and minor explosions still exist, as well as the possibility of a spill.
Authorities initiated the evacuation of Garden Grove residents, located near Los Angeles, last Thursday when the tank overheated, with about 50,000 residents affected by the weekend. Efforts were underway to cool the tank and prevent toxic leaks or explosions. By Monday, interior temperatures had lowered to 93 degrees F (33.9 degrees C), down from 100 degrees (37.7 degrees C) the previous day, according to Covey.
Community Reassured of Safety
Orange County Health Director Regina Chinsio-Kwong assured returning residents they are safe. The Environmental Protection Agency warns that methyl methacrylate exposure can lead to serious health problems. However, she emphasized that no contamination occurred and no vapors or fumes were released during the incident, making it safe to return home, even for those living near the newly designated zones.
“There was no contamination. There were no fumes. There were no vapors from this incident,” Chinsio-Kwong stated. “It should be safe; you should feel comfortable going home even if you’re across the street from that new zone line.”
Stabilizing the Tank
Purdue University engineering professor Andrew Whelton noted that the tank might soon cool enough for crews to safely manage the remaining material without sparking ignition. He advised that temperatures should ideally reach between 60 to 70 degrees Fahrenheit (15.6 to 21.1 degrees C) for optimal safety.
As the tank’s temperature rose, the methyl methacrylate turned from liquid to gas, increasing pressure and explosion risk. Whelton added that some of the chemical might have hardened into a stable, plastic-like substance, lowering tank risk further.
Orange County Supervisor Janet Nguyen mentioned ongoing air monitoring by the South Coast Air Quality Management District and sewer checks by the EPA. County health officials indicated that although the chemical is detectable by smell over large areas, it poses no harm.
Residents Express Relief
While the specifics of a catastrophic explosion remain undefined, officials dismissed the worst-case scenario. Kim Yen, a retiree who evacuated her Garden Grove home, expressed relief that the situation has improved. She closely followed the news and, though eager to return home, wants assurance of safety.
“I am happy and many of us are happy but, still, we are still on our evacuation,” she said.
Yen, living two blocks from the plant, praised the emergency teams. She said their work exemplifies heroism.
“They are really our heroes,” Yen commented.
Meanwhile, a park in Fountain Valley served as a refuge for evacuees, with many setting up temporary shelters or celebrating Memorial Day there.
GKN Aerospace’s Role
GKN Aerospace Transparency Systems, a British company supplying aircraft manufacturers, operates the plant. It focuses on making cockpit windows, canopies, and windshields for military and commercial aircraft. On Monday, the company removed external insulation from the tank to aid cooling efforts. In a statement, they acknowledged disruptions caused by the incident and pledged commitment to resolving the situation swiftly to allow residents’ prompt return.
Globally, GKN Aerospace employs around 16,000 people at 32 sites in 12 countries, providing components widely used in commercial and military aircraft.
A South Coast Air Quality Management District report disclosed that in 2025, GKN Aerospace agreed to pay over $900,000 to state regulators for recordkeeping, permit issues, and nitrogen oxide emissions violations.
Impact on Aerospace Supply Chain
The disruption at GKN Aerospace highlights vulnerabilities in aircraft component supply chains. Richard Aboulafia from AeroDynamic Advisory noted that the aerospace industry’s concentrated supply chains and existing strains make such disruptions challenging to absorb.
“There’s just not a lot of margin in the system,” he noted.
The aerospace sector’s relatively low production rates leave few suppliers for crucial parts, increasing the impact of facility disruptions.