Toxic Cloud Sends 16 at Plant to Hospital : Industry: Fumes at Anaheim factory were released by a ‘violent’ chemical reaction when workers poured acid into a barrel containing an unknown substance.

Sixteen workers at an airplane parts manufacturing firm were hospitalized Thursday for minor respiratory problems after a “violent” chemical reaction produced a yellow toxic cloud, officials said.

The incident, which occurred about 11:30 a.m. at Leach Corporation on Van Horne Way, forced the evacuation of about 200 people inside 10 buildings in the industrial park.

The cloud formed after workers transferred 30 gallons of used nitric acid into what was thought to be an empty 55-gallon drum, said Bret Colson, a city spokesman. However, the second drum contained another substance “which reacted violently with the acid,” he said.

Fire officials were unable to immediately determine what material was in the second drum.

Transferring acid between drums is part of the process of manufacturing switching devices for aircraft, Colson said.

The reaction produced a “yellow cloud similar (in size) to what you might see coming up from a family barbecue,” Colson said.

The injured workers, who complained of nausea and lung irritation, were taken to two area hospitals, Kaiser Permanente’s Anaheim Medical Center and Placentia Linda Hospital in Placentia. None of the injuries was serious, fire officials.

After the incident, police cordoned off a two-block area around the Leach Corp. building. By midafternoon, the cloud had dissipated and employees from nearby businesses were allowed to return to work.

Officials spent the afternoon making sure the plastic drum containing the acid was properly stored, Colson said.

The Leach Corp. workers were not permitted back in their building Thursday, but were expected to return to work today.