A chemical spill at the University of Birmingham saw 11 people undergo screening after they showed signs of exposure to a harmful gas.
Staff at the clinical immunology laboratories made their own way to A&E at the nearby Queen Elizabeth Hospital after they were evacuated because of the leak of hydrogen azide gas, shortly before noon on Tuesday.
A university spokesman said a member of staff had dropped a 200ml bottle containing a weak solution of sodium azide, commonly used as an anti-bacterial agent.
She added the 11 staff later returned to work having being given a “clean bill of health”.
Station commander Mark Lawton said their unit was sealed off until this morning (Wednesday) when staff at the research centre expect they will be able to remove it.
Mr Lawton, based at Dudley fire station, said azide is sometimes used as a gas in the production of car airbags and can cause irritation to the eyes, nose and throat.
Two fire engines from Woodgate Valley and Bournbrook along with a specialist hazardous materials officer were called out at about 1.20pm.
A spokeswoman for West Midlands Ambulance service said it was called at 12.16pm and dispatched its hazardous response team.
Mr Lawton added: “The chemical spillage had caused the release of a small quantity of hydrogen azide gas.
“Eleven people working within the unit were evacuated and self-presented at the Queen Elizabeth Hospital showing signs and symptoms of exposure to the gas.
“On advice from our hazardous materials specialist officer and on-site staff the room has been isolated and the chemical is being left to stabilise for 24 hours when it will be disposed by on-site staff.”
The university spokesman added: “The safety of our staff is paramount.
“We are pleased this minor incident was subsequently resolved.”