Around 40 patients and staff were evacuated from a ward at Sunderland Royal Hospital after an ammonia leak.
Firefighters were called to the hospital just before 5am on Tuesday and discovered around 10ml on ammonia had leaked from a fridge in a drugs room on a ward on the sixth floor.
The ward was evacuated and the drugs room was sealed. The fridge was removed by firefighters.
It was then taken away from the hospital to a secure compound at the hospital where it was rinsed and decontaminated.
The ward was cleared of ammonia gas and patients were let back in.