Residents reported a strong sulphur-like smell and a school was locked down while the children were assessed and decontaminated. Carterton’s South End School posted on social media there was a very strong smell of "ammonia rotten eggs" in the playground about 1pm.
"... a plane flew in a southward direction and one student had seen ‘stuff’ coming out of the plane — so we assume it was a fertiliser of some sort".
However, Fire and Emergency (Fenz) later discounted the plane theory.
Several pupils felt queasy and they were made to wash their faces and drink plenty of water.
The range of symptoms included nausea, vomiting, stomach pain and a temperature.
At least five ambulances and eight fire engines went to the school.
Wellington Free Ambulance said 40 children with "very minor" symptoms were treated at the school by paramedics.
Ten others with moderate symptoms were taken to Wairarapa Hospital in Masterton.
Fenz said about 100 children at the school were triaged and put through a decontamination process. Parents were asked to bring a change of clothes for their children.
By 7pm, the last of the 10 taken to hospital had been discharged, a hospital spokeswoman said.
She expected the regional public health service would be involved in trying to find the source of the problem.
Police said inquiries to find the source were continuing. They were door-knocking in the area and investigating the school grounds.
A Fire and Emergency spokesman, commenting on reports of a substance coming from a plane, said, "... that’s been unsubstantiated at this stage and we don’t believe it’s come from a plane — we just don’t know where it’s come from. That’s a mystery to us."
- Martin Johnston