Shell Canada says there was a hydrocarbon release within its manufacturing centre in Corunna Thursday morning.
The company said the emergency alarm sounded at around 8:30 a.m., and the Emergency Operations Centre was activated.
The release was been contained at the unit.
Shell said external air monitoring showed no offsite release, and all site personnel were accounted for.
The company notified the Spills Action Centre (SAC) and issued a community alert.
The all clear was given at around 10:38 a.m.