Aamjiwnaang residents were complaining of a rotten smell Thursday night.
Residents reported a strong smell of rotten eggs between 7pm and 9pm.
A message on the Community Awareness and Emergency Response Line says during restart procedures at Suncor's Sarnia Refinery, increased odours may be present.
Thursday morning, there was an on-site leak of boiler feedwater just after 9:30am. Although no hazardous materials were involved, the affected unit was shut down.
The Clean Air Sarnia and Area website, designed to show real-time levels of pollutants, showed no elevated levels during that time frame Thursday night.
Suncor says they're working with the Ministry of Environment and has deployed third-party air monitoring at Aamjiwnaang.
