Dive summary:

• Clean Harbors issued a warning yesterday as a release of volatile organic vapors seeped from the plant in southern Ontario.
• The gases leaked out for no more than 30 minutes and officials say there were not elevated levels of hazardous compounds.
• Similar incidents have happened before at the Clean Harbors plant but the effects of the leaks have never exceeded environmental standards.

From the article:

Clean Harbors reported no offsite impact following a vapour release at its St. Clair Township hazardous waste facility early Wednesday.

The company issued a warning Code 8 for the release of volatile organic vapours. The alert went out at 12:40 a.m. and an all-clear was issued by 12:56 a.m.

Air off-site was monitored and no elevated level of hazardous compounds or odours were detected, said general manager Jim Brown. ...