NOVA Chemicals St. Clair River site is monitoring onsite activities after a hydrocarbon release happened just before 12:30 p.m. Wednesday.
A code 8, requesting the assistance of police, was issued but an all-clear has since been given.
NOVA's Responsible Care Communications and Engagement Specialist Julia Iacovella said the issue has been isolated and there were no offsite readings.
Meantime, increased flaring and noise may be noticed at INEOS Styrolution on Wednesday.
In a message from the My Community Notification Network, the company said it's conducting maintenance at its Tashmoo Avenue site.