LANSING, Mich. — A new proposed state rule would require U.S. Steel to cut sulfur dioxide emissions at two of its Detroit facilities.

The state Legislature would still have to approve the new rule announced Thursday from the state Department of Environmental Quality after a 2010 federal review found sulfur dioxide levels to be above federal standards and spurred state action to scale back emissions.

The DEQ’s Air Quality Evaluation Section Chief Barb Rosenbaum says four other Detroit companies in addition to U.S. Steel voluntarily agreed to cut emissions, but U.S. Steel didn’t comply and forced the department to take action. Sulfur dioxide levels have fallen by 33 percent in southwest Detroit since 2010.

The Associated Press made a request for comment from a U.S. Steel spokeswoman.