ATA expects EPA to unveil NOx emissions proposal draft this week

The American Trucking Associations (ATA) says the Environmental Protection Agency (EPA) is poised to publish a draft notice of proposed rulemaking (NPRM) on nitrogen oxide (NOx) emissions standards for heavy-duty trucks this week. The Office of Management and Budget (OMB) completed its review of the draft proposal before the Independence Day holiday, according to Henry Hanscom, ATA’s chief advocacy and public affairs officer, who outlined the expected changes in a July 6 letter to members. The NPRM will formalize EPA’s intent to revise existing NOx rules, inviting public comment once released. EPA plans to retain the Biden-era requirement that heavy-duty truck NOx emissions drop to 35 milligrams per horsepower-hour from the current 200 mg/hp-hr. However, the trucking industry remains in limbo over critical details—particularly warranty requirements—that typically would have been clarified much earlier in the regulatory process. ATA anticipates the final rule will relax several provisions: rescinding an extended warranty mandate, restoring EPA’s previous warranty and useful-life requirements, expanding the availability and flexibility of compliance credits, and allowing temporary use of nonconformance penalties for manufacturers. The uncertainty has already prompted some fleets to delay new truck purchases, despite manufacturers having EPA 2027-compliant engines ready for deployment. At the 2026 Advanced Clean Transportation Expo in May, International Motors (a Traton division) revealed its EPA 2027-compliant S13 integrated powertrain, initially launched in August 2022. David Hillman, International’s vice president of integrated technology sales, told attendees that pricing for compliant engines remains undetermined, with fleets repeatedly asking about potential cost increases. “Not a week goes by that me and my team don’t get asked, ‘What’s the pricing on this?’ … We don’t know the pricing yet today,” Hillman said. “What we don’t want to do is [establish a] price given the regulations on the books right now, and then have an NPRM come out that dramatically changes that and then everyone has to reshuffle.” The looming regulatory uncertainty has carriers adopting a cautious “wait-and-see” stance on new tractor orders, even as manufacturers insist their 2027-compliant engines meet current standards. ATA supports emissions reductions but argues that the proposed flexibilities—paired with continued use of diesel exhaust fluid—will enable the trucking sector to build on decades of environmental progress. EPA Administrator Lee Zeldin announced in March 2025 that the 2022 Heavy-Duty Nitrogen Oxides (NOx) rule would undergo re-evaluation.