In a reversal of its reversal, the EPA said Thursday that it would enforce limits on dirty "glider" trucks after all.

Acting EPA Administrator Andrew Wheeler put the brakes on his predecessor's decision to not enforce an Obama-era rule on dirty diesel big-rigs.

CHECK OUT: States join to halt EPA's reversal on "glider" semi trucks

Glider trucks are new semi-truck bodies and chassis fitted with older diesel engines that predate emissions controls. Those trucks can emit up to 43 times more carcinogenic particulate matter and 13 times more nitrogen oxides than currently allowed by law for new trucks, but they cost $30-40,000 less that those with new, lower-pollution engines.

They were designed as a way to get more life out of engines that were in trucks that had been wrecked, but a new industry sprang up to sell thousands of them as a cheaper alternative to new trucks.

Under the Obama Administration, the EPA set limits on production of the trucks, allowing each manufacturer to sell only 300 finished gliders a year.

READ THIS: Pruitt leaves poison pill at EPA for glider-truck emissions rule

On his last day in office, President Trump's first EPA administrator, Scott Pruitt, reversed the Obama ruling, saying the EPA would not enforce it through the end of 2019.

Pruitt resigned July 5 amid a cloud of administrative and personal scandals unrelated to the "glider rule."

EPA Acting Administrator Andrew Wheeler

EPA Acting Administrator Andrew Wheeler

On Thursday, Wheeler reversed that ruling in a three-page memo to his deputies, according to a report in the Washington Post.

According to the Post, Wheeler said in the memo: "I have concluded that the application of the current regulations to the glider industry does not represent the kind of extremely unusual circumstances that support the EPA’s use of enforcement discretion," referring to the EPA's long-held discretion to decide which environmental regulations to enforce and which not to.

DON'T MISS: Fake science: University disavows study EPA cited to approve old dirty diesels in "glider" trucks

The memo reportedly notes that the agency suspends enforcement only in rare circumstances and that after consulting with EPA lawyers and policy experts.

Pruitt's decision to suspend enforcement of the glider rule was based on a discredited study by Tennessee Technological University, funded by Fitzgerald Gliders, the largest manufacturer of glider trucks. The university later disavowed its own study.