NOVA Chemicals has reported a hydrocarbon release from its Moore plant.
In a message to Aamjiwnaang First Nation Emergency Planning, the company says ethylene was released into the atmosphere for 47 seconds just after 11pm Monday.
Ethylene is used in polyethylene production and is a colourless, flammable gas with a faintly sweet and musky odour when pure.
The incident was reported to the Ministry of Environment and Climate Change at 1:18am Tuesday.
The company is reporting no off-site impact.