There was a leak Wednesday morning at Sarnia's Suncor Refinery.
On the Community Awareness and Emergency Response Line, the company says there was a small leak of water mixed with low levels of sour gas in one of its units.
Spokesperson Jennifer Johnson said the leak was quickly isolated and contained, but a distinct odour may have been noticeable for a brief period this morning.
"Notifications have been made to CVECO (Chemical Valley Emergency Coordinating Organization) and the Ministry of Environment, Conservation and Parks," said Johnson.
Johnson said increased flaring and noise are possible as work is conducted to repair the leak.