VALLEJO — One worker was in serious condition Friday while 90 others exposed to a carbon dioxide leak at a Northern California food processing plant have recovered, hospital officials said.

Workers at Ghiringhelli Specialty Foods in Vallejo began having difficulty breathing and some started vomiting due to what firefighters described as a gas leak in a kitchen fed by an external carbon dioxide tank.

The leak was capped but nearly all workers at the plant suffered at least some effects from the gas, Vallejo Fire Capt. Marty Culverwell said.

"It was shut off in the kitchen and the tank feeding the kitchen has also been secured,” Culverwell said. "It was contained and ventilated correctly.”

Firefighters arriving at the scene saw workers outside suffering from more serious symptoms of carbon dioxide exposure, including nausea, respiratory problems, fainting and difficulty seeing.

The plant’s owner, Mike Ghiringhelli, questioned whether the problem was as serious as it seemed.

"I think it’s a false alarm, ‘cause the air was fine,” Ghiringhelli told reporters outside the plant.

The recently opened 50,000-square-foot plant manufactures what the company’s website describes as private label fresh and frozen natural foods, including salads, pizzas and grilled meats.

An investigator from the California Division of Occupational Safety and Health was on the scene, said agency spokesman Dean Fryer. He said the investigation into the leak had just begun.

Firefighters said they did not find unusually high levels of carbon dioxide in the air inside the building but told KTVU-TV the doors to the plant had been open for some time when they arrived.

Sutter Solano Medical Center saw 45 patients for symptoms such as nausea, dizziness and trouble breathing, spokesman Sy Neilson said. All were released except for one who was admitted in serious condition due to more serious symptoms doctors wanted to monitor, he said.

Thirty patients were taken to Kaiser Permanente’s Vallejo Medical Center. None were expected to be admitted for treatment, spokesman Marc Brown said. At Northbay Medical Center in Fairfield, 16 patients were treated and released.

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