Hydrogen cyanide has been identified as the toxic chemical that sent four children at St Joseph’s School to the hospital.
Emergency services were called to the incident at the Church of the Holy Name on Sealy St, Ashburton, after one child fainted and others felt ill towards the end of the Eucharistic prayer about 9:30 am.
St John said two ambulances and an operations manager attended the incident, and four patients with minor injuries were taken to Ashburton Hospital.
A Fire and Emergency New Zealand spokesperson said firefighters detected extremely low amounts of hydrogen cyanide that barely registered. There was no further investigation.
St Joseph’s principal, Cath Blacklow, said in a statement that the pupils recovered quickly. Further testing showed no chemicals were detected at the church or areas tested within the schools connected with the student illnesses, she said.
St Joseph’s School teaches students aged five to 13.
The Ministry of Education offered the school support.
Hydrogen cyanide is a highly volatile, colourless, poisonous liquid that readily evaporates to a gas with a faint, bitter-almond odour.
It is highly toxic because it blocks cellular respiration, so small inhaled doses can be rapidly fatal. It is also highly flammable, which adds fire and explosion hazards to its toxicity.
Low-level exposure can cause symptoms such as headaches, vertigo, anxiety and shortness of breath, according to the World Health Organisation.
Hydrogen cyanide is often used to control insects and other pests, to fumigate buildings, and in metal treatment processes.
