High flaring at NOVA Chemicals' Corunna plant sent plumes of black smoke into the sky early Thursday afternoon.
The smoke was blown toward the city on brisk south-southwest winds.
Company spokesperson Meaghan Kreeft says a plant upset caused the increased flaring.
"Flaring will continue until we return to normal operations," says Kreeft. "We're investigating the cause."
Kreeft says during unit start-up over the coming days there may also be some increased noise.
She says information updates will be shared as needed via the Community Awareness Emergency Response update line at 1-855-472-7642.
