Fire and Emergency NZ has revealed the toxic chemical detected at an Ashburton school, which led to four people being taken to hospital, was hydrogen cyanide.
A Fenz spokesperson confirmed its crews “detected extremely low amounts of hydrogen cyanide at the church” at St Joseph's School on Havelock St last Friday.
“It was such a low amount that it barely registered. There was no further investigation.”
The spokesperson did not clarify the source of the chemical. But it reportedly caused some pupils to start feeling unwell.
Fenz sent three crews to the school just before 10am, and called for a hazmat unit from Timaru.
Firefighters left soon after and the hazmat unit was stood down before arriving.
At the time, Fenz said testing showed low readings of an unknown chemical, which has now been revealed to be hydrogen cyanide.
Hydrogen cyanide is a highly toxic, colourless (or pale blue), and volatile liquid or gas with a distinct bitter almond odour.
It can potentially block oxygen utilisation and cause death, especially in confined spaces.
Hato Hone St John reported two ambulances and an operations manager attended the scene where four patients, all in minor condition, were transported to Ashburton Hospital.
St Joseph's principal Cath Blacklow had initially declined to comment on the incident but provided a media statement on Wednesday.
"Last Friday, a number of pupils fell ill at St Joseph's School and at our neighbouring church.
"Emergency personnel discovered very low levels of a chemical.
"Emergency personnel did not consider any additional investigations were necessary and thankfully, the pupils recovered quickly.
"As a precautionary measure, and given our high priority for student safety, the school asked that more testing be undertaken, including by professional fire crew and tradespeople.
"It was established that no chemicals were detected at the church or areas tested within the school that would be connected with the student illnesses on Friday."
The Ministry of Education confirmed it is in contact with St Joseph’s and have offered support if needed.
“Fenz attended the incident on Friday and are the lead agency for assessing and responding to the chemical detection,” a spokesperson said.
Questions about the substance involved, its source, or any investigation were referred to Fenz.
■ LDR is local body journalism co-funded by RNZ and NZ On Air.
