The Environmental Protection Agency will now enforce an Obama-era rule that limits diesel truck emissions, reversing one of the final decisions made under former agency chief Scott Pruitt.
"I have concluded that the application of current regulations ... does not represent the kind of extremely unusual circumstances that support the EPA's exercise of enforcement discretion," acting Administrator Andrew Wheeler wrote in a memo released Thursday.
Without referring to Pruitt by name, Wheeler noted the decision made earlier this month was both proposed and approved by EPA offices on the same day, and that a federal judge has temporarily halted the decision from taking effect.
The decision not to enforce the rule was made because the Trump-era EPA is looking to change a regulation about "glider" trucks.
Glider trucks are new vehicles with old engines, traditionally pulled from vehicles where the body was damaged or broken, such as in a crash. But following the development of tighter emission standards for diesel vehicles in the mid-2000s, glider trucks also became an attractive option to members of the trucking industry seeking to avoid the new technology, which has been criticized as more costly and less reliable.
The Obama administration had capped the number of the trucks each manufacturer could make every year, and the Trump administration has been lobbied by the glider truck industry to loosen the cap.
The decision by the Pruitt-led EPA was opposed by an unusual coalition that included manufacturers of new diesel trucks and environmental groups.
The Environmental Defense Fund, one of the groups that asked the federal court to stay the decision under Pruitt, said Wheeler's memo "is a huge win for all Americans who care about clean air and human health."
Wheeler's memo did not say whether he intends to propose a replacement for the Obama-era rule on the trucks' emissions.