The U.S. Environmental Protection Agency (EPA) said Monday it is seeking input on its plans to develop cleaner emission standards for heavy-duty trucks. 

Known as the Cleaner Trucks Initiative (CTI), the program was announced in late 2018. This week's Advance Notice of Proposed Rulemaking (ANPR) marks the next step in the agency's long-term efforts to reduce air pollution from heavy-duty engines on the nation's highways. The ANPR seeks public input on the CTI, which would establish new, more stringent emission standards for oxides of nitrogen (NOx) and other pollutants from heavy-duty truck engines.

EPA Administrator Andrew Wheeler said Monday that the CTI will "modernize heavy-duty truck engines, improving their efficiency and reducing their emissions, which will lead to a healthier environment."

Wheeler acknowledged that the U.S. has made "major reductions" in NOx emissions in recent years, and said the current initiative aims to further those efforts. In a statement, the EPA said that U.S. NOx emissions fell by more than 40% between 2007 and 2017. 

The EPA last revised its NOx standards for on-highway heavy-duty trucks and engines in January 2001. 

Industry groups immediately weighed in on the issue. The Truck and Engine Manufacturers Association (EMA) said it looks forward to working with the EPA in response to this week's ANPR. The group also pointed to its members work to advance clean engine and vehicle technologies over the past 20 years, which it says have helped reduce NOx and particulate matter emissions to "near-zero levels."

"We have the opportunity to build on and repeat our past success, but to do so we need the Agency to lead a collaborative, data-driven process to determine both the feasibility and cost-effectiveness of any future regulations," EMA President Jed Mandel said in a statement Monday. "Through the Cleaner Trucks Initiative, EPA can assure that any future regulations are not only cost-effective, but also provide sufficient regulatory lead time, stability, and certainty."

The EPA said it plans to publish a proposed rule early this year.