South Yorkshire fire crews attend chemical incidents
South Yorkshire Fire Service was called to two chemical incidents overnight.
Fire crews and a specialist decontamination vehicle were sent to Doncaster Royal Infirmary A&E just before 04:00 BST.
Four Royal Mail sorting office workers were aerated after being contaminated with a chemical when a package burst open at the sorting office.
Earlier, fire crews were called to Gleadless Road in Sheffield where a car had been vandalised.
The two incidents were unrelated, the fire service said.
Steve Makepeace of South Yorkshire Fire Service said the Royal Mail staff, two men and two women, suffered a burning sensation and reddening of the skin after the chemical leaked on to their hands.
The chemical was identified as concentrated Cesium Hydroxide, a cleaning fluid often used in beauty salons and spas, Mr Makepeace said.
The substance was found not to be harmful.
In Sheffield, fire crews were called to Gleadless Road at 23:30 BST after a car had been vandalised, Mr Makepeace said.
The car window was broken and a chemical was poured on to the driver's seat.
The identity of the chemical used on the car is still under investigation, Mr Makepeace said.