U.S. Markets open in 7 hrs 54 mins
1 / 6

Petroleum Coke Neighborhoods

The Willis Tower in downtown Chicago provides a backdrop to a huge mound of petroleum coke, or pet coke, in the a residential area southeast part of the city. An increasing volume and size of petcoke piles is causing environmental concerns for residents in this working-class neighborhood. (AP Photo/Charles Rex Arbogast)

Petroleum Coke raising Environment Concerns in the Midwest

The images are startling. Billowing black clouds darken the daytime sky as wind-driven grit pelts homes and cars and forces bewildered residents to take cover.

The onslaught, captured in photos and video footage from Detroit and Chicago this year, was caused by the same thing: brisk winds sweeping across huge black piles of petroleum coke, or "petcoke," a powdery byproduct of oil refining that's been accumulating along Midwest shipping channels and sparking a new wave of health and environmental concerns.