Emergency services responded to a chlorine incident at the Tegel factory on Carmen Road in Hornby this afternoon.
St John said they were notified of the incident at 3.14pm and sent two rapid response vehicles and one ambulance.
One person was assessed at the scene and transported to Christchurch Hospital in a moderate condition.
St John ambulance took one person to hospital in a moderate condition.
A Fire and Emergency spokesperson said three fire appliances were called to the Tegel factory, including crews from Wigram and Ilam stations, as well as a command unit from Christchurch Central Station.
Carmen Road remained open, but motorists were advised to take extra care while passing the scene.
