By Chris Hardy

Mackie Academy in Stonehaven was evacuated yesterday after a janitor preparing to clean the indoor swimming pool accidentally created a toxic gas that spread through the school.

School rector Peter Campbell said a janitor was putting fresh chemicals into the swimming pool plant to make the chlorine to disinfect the water.

“Inadvertently he put the chemicals into the wrong tanks,” he said. “There was a residue in them. This caused a chemical reaction and there was a release of chlorine gas.

“He is very experienced and had done it loads of times before but for some reason he put the chemicals in the wrong bins. When he realised quickly what he had done and that there was gas forming, he called the fire brigade who told us to evacuate the school immediately.”

Two staff members exposed to the gas, including the janitor, were taken to Aberdeen Royal Infirmary as a precaution. They were discharged soon after and returned to the school.

An inhaler, normally carried by a pupil with asthma, was left behind during the evacuation and was retrieved for the pupil.

The alarm was raised at 8.30am as 900 pupils and 130 staff prepared to start the day.

Firefighters wearing breathing apparatus and gas-tight suits entered the school and ventilated it.

A Grampian Fire and Rescue spokesman said the gas escape was caused by a mix of sodium hypochlorite and sodium bisulphate.

The chemicals were placed in a sealed container and taken off-site by a waste disposal company.

On completing the ventilation of the school using fans, the all-clear was given at about 11.30am.