An investigation has been launched after an ambulance was called to Upper Hutt's community pool yesterday to treat sick children.
About 15 10 to 15-year-olds experienced symptoms of irritated eyes and breathing difficulties while at the H2O Extreme aquatic centre.
Eleven patients were later reported to be in a stable condition at Hutt Hospital emergency department.
The slides had been closed after a reading showed high chlorine levels that remained within the maximum safely allowed. The slides re-opened when chlorine levels dropped again.
A child reported feeling sick after using the slides and they were closed again, first aid was administered and an ambulance called.
The building was then cleared as a precaution.
Worksafe said the most likely cause was a lack of ventilation in the slide area, along with heavy use of the slides, but further investigation was required.
Upper Hutt City Council said there had not been any chemical spill or leak.
Council community services director Mike Ryan said the incident was deeply regretted.
"Our thoughts are with the children and their families who were affected by it yesterday afternoon," Ryan said.
The pool is open again today, but the slides will be closed while further investigations take place.
RNZ
