The American Trucking Associations (ATA) is calling on the Environmental Protection Agency (EPA) to push back the start date of the next phase of nitrogen oxides (NOx) emission limits for heavy-duty trucks by four years. The new standards are currently slated for 2027, but ATA is asking for implementation to be postponed until 2031.
In an August 13 letter obtained by Transport Topics, ATA warned that the “heavy-duty NOx rule imposes substantial compliance costs and operational burdens” during a period of “historically difficult market conditions” for the trucking sector. The group pointed to persistent weakness in freight demand and rising inflation, saying the 2027 deadline would intensify pressures on carriers.
ATA’s letter requested that the EPA conduct a complete reassessment of the current standards, including NOx stringency levels, warranty obligations, useful life requirements, and related technical provisions. The group suggested the agency finalize this review by the end of 2026, giving engine manufacturers enough lead time to meet the updated requirements by 2031.
The association argued that the delay would allow truck makers to continue producing reliable, cost-effective engines that comply with the existing 0.20 g/bhp-hr NOx standard, while providing economic relief to the industry without halting progress in emissions reduction. ATA emphasized that modern trucks already emit 99% less NOx and particulate matter compared to older models and reaffirmed its commitment to further improving air quality.
The letter was co-signed by numerous state trucking associations, including those representing California, Colorado, Florida, Georgia, Hawaii, and Idaho. National groups such as the National Tank Truck Carriers and the Truckload Carriers Association also lent their support. The correspondence was addressed to EPA Administrator Lee Zeldin.
Earlier in the year, the EPA announced it would review both its greenhouse gas standards for heavy-duty vehicles and the NOx rule. The agency, under the Biden administration’s “Clean Trucks Plan,” defended the 2023 NOx limits as the most significant emission reductions achievable starting in 2027, factoring in costs as required by the Clean Air Act.
However, the current EPA leadership, aligned with President Donald Trump’s policy direction, has criticized the Biden-era plan as overly costly and likely to make essential goods more expensive. The agency has said it is committed to protecting the environment while reducing costs for Americans, bolstering U.S. manufacturing, restoring legal balance, and empowering states to make their own regulatory decisions.
ATA concluded its letter by stressing that a delay would give the trucking industry and its supply chain partners the stability they need in the short term, while a full standards review would safeguard the sector’s ability to deliver goods efficiently and affordably. Without these steps, the group warned, the economic strain on fleets and equipment manufacturers could become unsustainable.
