The U.S. Environmental Protection Agency won tentative—and unusually unified—praise from both industry and environmentalists for its plan to overhaul smog rules for heavy-duty trucks.

The agency’s “Cleaner Trucks Initiative” aims to slash nitrogen oxide emissions, a major precursor to smog. The initiative also seeks to ease “overly complex and costly requirements that do little to actually improve the environment” in the current NOx rules, EPA Acting Administrator Andrew Wheeler said in a conference call during which the agency described the scope of the project.

Though clear-air advocates acknowledged the initiative could yield pollution reductions, they wanted to see more detail in light of the Trump administration’s track record of moves to weaken or eliminate environmental regulations.

“This may be the first rulemaking initiated by the Trump administration that is actually designed to reduce air pollution,” said Paul Billings, senior vice president for public policy at the American Lung Association. “The details are important and there are many questions.”

Truck Pollution

Bill Wehrum, assistant administrator for the EPA’s Office of Air and Radiation, said it’s time to update the 18-year-old standards in part because of heavy-duty trucks have become a larger contributor to harmful emissions overall, especially in cities and near ports with heavy truck traffic.

The policy update also comes as California clean-air regulators are developing tougher truck requirements of their own, and say nationwide rules are also needed because many large trucks that haul goods—and pollute—inside the state were purchased elsewhere.

California is further along in drafting new NOx standards than the EPA, and the agency plans to work with the state on the issue, Wehrum said.

“I can’t say we’ll agree with everything they’re thinking and want to do but, you know, that’s nature of the regulatory process,” he said.

Big-Rig Emissions

Jed Mandel, president of the Truck and Engine Manufacturers Association said the proposal represents a chance to modernize how the agency oversees big-rig emissions, focusing more on real-world emissions than on laboratory tests to assess progress.

“We support the move toward looking at the program to ensure that we have better, more real-world focused emissions reductions,” said Mandel, whose association represents 30 heavy-duty engine and truck manufacturers including Cummins Inc., Navistar Inc. and Volvo AB.

The EPA may change its laboratory testing procedures to reflect more driving situations when emissions may be higher but aren’t captured by the current lab tests, Wehrum said. It will also review whether on-board equipment could replace the lab tests used today to monitor whether trucks remain in compliance with pollution requirements as they rack up miles.

New Congress

Dave Cooke, a senior vehicles analyst with the Union of Concerned Scientists, said the push reflects a broad recognition that further reductions of NOx emissions are possible and future standards could better reflect true emissions levels on the road.

“This would be a welcome change of pace,” Cooke said in an email. “At the same time, I’m wary of such a pivot and am deeply skeptical of this administration’s ability to actually follow the science and publish a regulation in the best public interest.”

The pivot to update the truck standards comes as Democrats in the House of Representatives prepare their agenda for the next Congress, where they’re expected to wield their newfound majority power to closely scrutinize Trump’s environmental rollbacks.

“With the Democrats taking over the House, and the potential for some actual oversight and accountability from Congress, EPA is feeling pressure to show that they are taking actions to protect the environment and save lives instead of what they’ve done under Trump to this point,” said Amit Narang, a regulatory policy expert at the watchdog Public Citizen.

Billings, of the Lung Association, said he was concerned that the EPA was still considering whether to re-instate a provision exempting so-called glider kits from emissions standards that apply to newly manufactured tractor-trailers. Gliders are new truck cabs and chassis that are fitted with used engines designed for older, less stringent pollution standards.