This is because hot water and steam were released into a room in a school when a water boiler's safety release valve was activated. The valve should have been vented to the outside.
Nobody was hurt in this incident and the risk remains low but schools are being advised as follows:
The next time that your heating/water heating appliances in school are serviced please ask the engineer to check that any safety release devices are vented to the outside as appropriate, in accordance with current regulations and standards.
If you have any questions about this matter please contact your service engineers direct.