A hazardous chemical leak that prompted the evacuation of more than 50,000 residents in Orange County, California, has taken a potentially positive turn after crews discovered a pressure-relieving crack in the industrial tank at the centre of the incident. The leak began on Thursday at the GKN Aerospace facility on Western Avenue in Garden Grove, and evacuation orders were expanded on Friday to cover neighbourhoods in Garden Grove, Cypress, Stanton, Anaheim, Buena Park and Westminster.
Officials said the discovery at the site could alter their approach to the crisis, which has entered its fourth day. Orange County Fire Authority Interim Chief TJ McGovern said the new information "could change our trajectory and our strategy to this event", describing the overnight operation as successful. California State Senator Tom Umberg said the tank's temperature reached 100 degrees during the night, the highest reading possible on monitoring equipment, but that the pressure release may help avert the two main concerns: an explosion or a toxic vapour plume.
Earlier, officials had warned of two possible catastrophic outcomes. Incident Commander Craig Covey said the tank could either fail and spill between 6,000 and 7,000 gallons of chemicals, or enter thermal runaway and explode, threatening surrounding tanks. In response, Governor Gavin Newsom declared a state of emergency on Saturday to free up state resources, stating that the safety of Orange County residents was the top priority.
Orange County District Attorney Todd Spitzer has announced an investigation into the incident and encouraged potential whistleblowers from GKN to come forward. Meanwhile, a group of Garden Grove residents has filed a class-action federal lawsuit against GKN Aerospace Transparency Systems, which operates the facility, arguing that property values in the surrounding community are likely to be affected regardless of the outcome.
The leaking substance, methyl methacrylate, is a flammable, colourless liquid used in the production of resins, plastics and dentures. It can irritate the lungs, eyes and skin, and in high doses may cause reduced lung function, dizziness and memory problems, according to the Environmental Protection Agency. Air monitoring around the evacuation zone has so far shown pollution levels within normal limits. Dr Regina Chinsio-Kwong, Orange County's top health officer, said those outside the evacuation zone should not expect any health impact, while urging evacuees to comply with the order. GKN Aerospace has apologised to residents and businesses and said it is working around the clock to mitigate the risk of a leak. The company previously agreed in 2025 to pay more than $900,000 to settle state regulatory violations involving recordkeeping, permitting and nitrogen oxide emissions.
