Nova Chemicals in Corunna, south of Sarnia, evacuated staff to a “safe location” Wednesday after a potential leak triggered plant alarms, the company said. Hydrogen sulphide, which has a rotten egg odour, can paralyze the human sense of smell and cause death at high enough concentrations. The ministry spokesperson said staff are investigating why Nova didn’t immediately report the spill.

It’s not clear when the leak began — a source said staff were warned that “the leak happened last night and (was) still not contained” — but the chemical involved Wednesday afternoon was hydrogen sulphide, said an alert issued by the nearby First Nations community of Aamjiwnaang.

The Trudeau government says its plans to toughen Canada's environmental laws could address serious health concerns exposed by a joint media investigation into Sarnia's petrochemical valley.

An internal document obtained by The Price of Oil investigation reveals accusations from Ontario engineers that the provincial government has 'ignored' a First Nation's chemical pollution concerns.

The announcement comes after joint investigation by Global News, the Toronto Star, National Observer, The Michener Awards Foundation and journalism schools at Ryerson and Concordia.

Ontario’s Environmental Commissioner Dianne Saxe said it’s “truly shameful” what is happening to residents living near what’s known as Sarnia’s “Chemical Valley.”

There are 57 polluters registered with the Canadian and U.S. governments within 25 kilometres. Are the chemicals, spills and illnesses related?

"Oil is king in a province where resistance is small." - University of Regina journalism students who researched and produced this documentary on Saskatchewan's oil and gas industry.

Saskatchewan government has insisted that public safety is its "number one priority," while declining all interviews related to The Price of Oil investigation.

The Price of Oil is the largest national journalism collaboration in Canadian history. Here's how it was put together and what it means for Canadians.

There's something deadly lurking in the rolling hills, pastures and valleys of Saskatchewan.

For victims of toxic sour gas leaked from the operations of Saskatchewan's powerful oil and gas industry, crying foul in public can have serious consequences.