As California officials rushed to cool down a chemical tank at risk of leaking or exploding, they said they’re evaluating additional measures to neutralize the threat to more than 40,000 residents and address the “unprecedented” situation.
Residents who live in the area around the GKN Aerospace facility in Garden Grove, California, south of Los Angeles, were ordered to evacuate after officials announced on May 21 that a large tank storing methyl methacrylate had overheated, causing it to begin venting vapors.
Despite initial efforts to cool the tank and its contents, Craig Covey, the incident commander with the Orange County Fire Authority, said on May 23 the internal temperature of the tank had increased to 90 degrees, averaging an increase of about a degree an hour.
Covey warned that the tank could rupture and split, or it could or explode. However, officials are still in talks with experts to find solutions, he said, adding, “letting this thing just fail and blow up is unacceptable to us.”
Additional updates are expected on May 24.
Chemical crisis forces evacuations in Orange County
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A drone picture shows water being sprayed on a tank as a chemical incident involving a failing tank of flammable liquid called methyl methacrylate, used in the aerospace industry, has forced an evacuation in the surrounding area in Garden Grove, California, U.S. May, 22, 2026.
(Caroline Brehman, REUTERS)Have there been changes in pollution levels at or near the site?
In an update late on May 23, Harry Allen, an onsite coordinator with the Environmental Protection Agency, said they had deployed 24 stationary air monitors to operate around the clock until the scene is “secure,” and the stations had not reported any contaminants.
He added the team had installed specialty equipment to “ensure that no gas is released from the tank at the source of the incident.”
Jason Low, an executive officer with the South Coast Air Quality Management District, also reported normal levels from its mobile air quality monitoring efforts in the evacuation zone.
What’s the latest on efforts to cool the chemical tank?
Measures have been underway to cool the tank and its contents to reduce the risk of a leak or explosion, according to the Orange County Fire Authority.
On May 23:
Gov. Gavin Newsom issued a state of emergency for Orange County. The procedural step unlocks additional authority to address emergencies, such as state resources for sheltering locations.
GKN Aerospace apologized to the community for the disruption and said its employees were “fully focused” on working with emergency services, specialized hazardous materials teams and local authorities to resolve the situation in a timely manner.
A drone picture shows water being sprayed on a tank as a chemical incident involving a failing tank of flammable liquid called methyl methacrylate, used in the aerospace industry, has forced an evacuation in the surrounding area in Garden Grove, California, U.S. May, 22, 2026.
What is the evacuation zone?
On May 23, Nick Freeman, a fire authority division chief, displayed a map in a post on X showing rings of a “blast zone” around the facility where homes could be damaged and residents could be injured. The map also outlined plumes to the north of the facility where residents could be exposed to vapors from the tank.
The evacuation zone has been roughly defined by the city of Garden Grove as south of Ball Road, north of Trask Avenue, east of Valley View Street and west of Dale Street.
Nick Freeman with the Orange County Fire Authority displays a map on May 22 showing rings where residents could be at risk of feeling a blast and receiving injuries from a possible tank rupture at GKN Aerospace in Garden Grove, California and a plume where residents could be exposed to vapors, in this screenshot from the Orange County Fire Authority’s update on x.com.
What is methyl methacrylate? what’s the risk to residents?
Methyl methacrylate, a colorless, volatile, flammable liquid, is used in the manufacture of resins and plastics, according to the EPA. The product has a “sharp, fruity smell,” according to a California Department of Public Health advisory. Breathing its vapors can irritate the skin, eyes and mucous membranes in humans, and may cause allergic reactions.
As long as evacuation orders are followed, no exposure to the product is expected, according to California’s health department. Those exposed may or may not develop health effects.
In previous cases, humans exposed to the product have reported both short and long-term respiratory effects. The EPA classifies the material as non-carcinogenic.
Kevin Hatch of Garden Grove sits in his car with his dog, Smokey, outside the Ocean View High School gymnasium, a temporary shelter opened after thousands were ordered to evacuate because of an overheated chemical tank in Huntington Beach, California, on May 23, 2026.
Short‑term exposure to the product can occur when breathing in vapors near a spill or release. Skin contact is also possible. Pregnant people should take special care to avoid breathing in fumes.
The product is widely used to manufacture a range of shatter-resistant acrylic materials such as Plexiglas, as well as resins, coatings and adhesives, California health officials said. Dentists use it to make crowns and fillings, and it has also been used to make bone cement for orthopedic procedures.
What is GKN Aerospace?
GKN Aerospace, headquartered in the United Kingdom, manufactures components for civilian and defense aerospace industries, including windows, engines and fuselages. The company reports 32 manufacturing locations in 12 countries.
A drone view shows water being sprayed during a chemical incident involving a leaking tank of methyl methacrylate, a flammable liquid used in the aerospace industry, forcing an estimated 40,000 to evacuate in the area surrounding Garden Grove, California, May 23, 2026.
Contributing: Paris Barraza, Kate Franco and Kristin Scharkey, USA TODAY and USA TODAY Network.
Dinah Voyles Pulver, a national correspondent for USA TODAY, covers climate change, weather, the environment and other news. Reach her at dpulver@usatoday.com or @dinahvp on Bluesky or X or dinahvp.77 on Signal.
This article originally appeared on USA TODAY: Garden Grove chemical tank triggers evacuations during explosion risk