Wayne County, Mich., is a throwback to the days of heavy Detroit manufacturing. It's a place where things are made, the furnace in which North America's automotive industry was forged.  

More than 180 industrial businesses, including stamping plants, assembly lines and oil refineries still, churn out thousands of parts and gas and asphalt for the auto industry every day.

It's a major source of American manufacturing and it's also a source of pollution for Windsor, Ont.

"We get more than our fair share of these toxic chemical exposures [in Windsor]," said James Brophy, an occupational and environmental health researcher at the University of Windsor.  

"Many parts of Canada are being exposed to these facilities in New York, Ohio and Michigan and so forth, so it's not just in Windsor," Brophy said. "But Windsor is particular because historically we're right in the industrial heartland of the United States."

Though he wasn't speaking about specific numbers, Brophy will be participating in a forum Wednesday, sounding the alarm on high air pollution in Windsor and Essex County.

One of these pollutants is sulphur dioxide, a colourless gas that is a byproduct of the industries that have driven life in Windsor and Detroit for the past 100 years. Exposure to it can cause lung problems and it is known to be a precursor to acid rain.

In 2013 alone, 33.5 kilotonnes of sulphur dioxide were emitted into air just kilometres away from the Canada-U.S. border, according to data from the Michigan Department of Environmental Quality released to CBC News through a freedom of information request.  

Detroit Refinery

Marathon operates a petroleum refinery in Detroit. (Michele Renee Johnson/Facebook)

In 2013, Wayne County's sulphur dioxide emissions was 33,500 tonnes. That's nearly 15 per cent of the total sulphur oxide emissions for the entire province of Ontario during that same year.

"For the last four or five decades, Windsor's air quality was considered the worst in Canada," Brophy said. "A major source of that poor quality originated in the United States."

"You had the steel plants, lead smelters, we've got four coal-burning power stations going full-tilt [in Michigan] and that's not counting what's coming in from Ohio. Windsor has been kind of a hot spot for this and Windsor's air pollution arises in the United States," he said.

Multiple sources of sulphur dioxide emissions 

While the federal Ministry of the Environment and Climate Change and Ontario's environment ministry note Windsor's level of ambient sulphur dioxide — the amount of sulphur in the air — is below national standards, the city's ambient level of sulphur dioxide exceeds the national average, even though it does not have any industrial sources that report emitting sulphur dioxide to Environment Canada.

The national standard for ambient sulphur dioxide is 11 ppb in Canada and the national average for ambient level of sulphur dioxide is 1.39 ppb. The level is 2.6 ppb in Sandwich west, for example.

The only reported sulphur dioxide emitters in the area are located in Michigan.  

"Canada and the United States have a legal obligation not to poison each other."  - James Brophy, University of Windsor 

"It's important to note that air quality in Windsor is impacted by more than local sources of sulphur dioxide," an Ontario environment ministry spokesman wrote CBC News in an email.

"There are regional and transboundary factors that affect levels of pollutants in Ontario, such as weather patterns and emissions from industrial activities in border states."  

But Windsor is not powerless in trying to curtail emissions from Michigan.

There are treaty obligations which require both Canada and the United States to adhere to air quality standards and the federal environment ministry says scientists are working to evaluate the effects of Canadian and U.S. emissions.  

Brophy says those regulations need to be more strictly enforced.

"Windsor has a long history of having an effect on what Americans do or don't do," he said. "We share an international border, we have the International Joint Commission on the Great Lakes. By treaty, we share a common airshed and a water source."

"Each party, Canada and the United States, have a legal obligation not to poison each other."

With files from the CBC's Katera Zappacosta