Workers are overcome by chemical mix
One worker was taken to hospital and another eight put in isolation after a suspicious acidic substance was found at a factory. A white powder was discovered at G&P Batteries Ltd in Darlaston.
More than 35 firefighters attended after employees experienced breathing difficulties and dry eyes.
Emergency services were called to the factory in Willenhall Road at 5.40pm yesterday.
West Midlands Fire Service spokesman Steve Harris said it was believed that the reaction was caused by "inadvertent mixing of chemicals on site".
An investigation has been launched into how this happened.
Mr Harris added: "The white powder was discovered by a couple of operators at the firm sorting out some batteries. One then reported feeling some adverse affects from it. He was taken to hospital prior to fire crews' attendance."
A further eight people were treated on the scene and monitored by ambulance crews.
The employees were kept isolated in the factory until they were decontaminated by firefighters. It is believed two people had direct contact with the powder.
G&P Batteries specialises in waste battery collection and battery recycling.
