A HOSPITAL casualty unit was closed after two recycling centre workers arrived in reception contaminated by a mystery chemical.
Darlington Memorial accident and emergency department was shut for two hours on Friday amid fears the chemical could harm staff and patients.
The men had been working at Total Recycling Services, in Lingfield Way, Darlington, when a spillage occurred.
The chemical was later identified as mercaptoethanol, which can cause skin irritation and breathing difficulties.
It is understood the men were not seriously hurt and were later discharged.
The casualty unit was ventilated and reopened after about two hours.
Alex Foreman, managing director of Total Recycling Service, was handling enquiries about the incident at the site gate on Friday morning.
He said: "We have a zero tolerance attitude to these matters and the men were sent to hospital as a precaution.
"The spillage was very small - probably no more than a litre and we have two chemists on site who are now cleaning it up."
County Durham and Darlington NHS Foundation Trust, which runs the hospital, said in a statement: "A&E was closed at about 10.45am after two adults presented at the department who had been contaminated by an unknown chemical.
"The department was closed in order to limit risk of exposure to other patients and staff."
The hospital said A&E remained open for life threatening emergencies only.
The statement added: "The chemical was identified as mercaptoethanol, which on contact causes irritation of the skin or eyes and can cause breathing difficulties or shortness of breath.
"It is unlikely to cause long term health problems.
"Following decontamination of the individuals affected and ventilation of the department, A&E reopened at 12.45pm.
"Patients and staff in the department at the time have been advised to contact their GP if they experience symptoms."
The fire service was called to the hospital but took no action.
Darlington Borough Council's civil contingency unit was notified about the closure of the A&E department. Police were also informed about the incident.