Poor Detroit. In addition to facing bankruptcy, the possible sale of the art in their museums, and the ire of pundits all over the world, they also dealt with a giant cloud of petroleum coke this week.

What the hell is petroleum coke, you ask? It's a rocky substance similar to coal that is a byproduct of petroleum refining. It is sometimes used as an industrial fuel. Although not officially classified as toxic, it can contain heavy metals or sulphur found in crude oil, meaning it's probably not great to breathe in.

And Detroit has a three-story stockpile of the stuff placed along the Detroit River near the Ambassador Bridge that happens to be owned by a Koch Bros. company called Koch Minerals. Normally, it's contained with epoxy, but that broke this weekend to load some of it onto a ship, inadvertently causing a thick cloud of it to blanket the city skyline.

Not only is Detroit upset about this, the Canadians are too, because the big cloud blew into Windsor as well. Here's the Toronto Star quoting Windsor resident Randy Emerson, who shot the video above:

For months, tall black piles of petroleum coke, commonly called pet coke, have been controversially stored on industrial property in Detroit near the Ambassador Bridge, prompting concerns from local residents over potential environmental and health impacts.

According to Emerson, a member of the Windsor on Watch environmental group, those fears came to fruition on Saturday.

“Pet coke shouldn’t be stored on a riverfront, that’s for sure. It should be in a building,” he said of the byproduct of Alberta heavy crude, which is used as a cheap replacement for coal. Detroit Bulk Storage, the company responsible for storing the pet coke, did not return calls from the Star on Wednesday.

The petcoke piles have been sitting around for months without a permit, although after the cloud hit the company that owns that land went hunting for one, according to Michigan Radio. Probably a good idea, that.