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.