The Environmental Protection Agency (EPA) proposed changes on July 9, 2026, to Biden-era environmental rules aimed at reducing pollution from heavy-duty vehicles, including buses and large trucks. The proposal includes scaling back and postponing two provisions related to warranties and the useful life of emissions-reducing technology.

The current requirement for truck engines to automatically operate at reduced power if emissions reduction systems are not working would be removed under the proposal. This automatic power reduction requirement would be replaced with a driver alert system. Additionally, the proposal allows truck manufacturers to pay penalties instead of complying with the rules while they develop compliant engines.

EPA Administrator Lee Zeldin stated the changes would help manufacturers continue to improve their vehicles. He said, "If finalized, these changes will help manufacturers keep improving their vehicles without being forced to rush products to market before they're ready." Zeldin added, "The rules changes will ease real burdens for operators." The American Trucking Association had stated in February that Biden-era policies would require a premature rollout of commercial motor vehicles with unproven engine technologies onto highways.

The EPA's analysis suggests these changes would save the trucking industry between $4,130 and $6,152 per affected diesel engine. However, the agency's analysis also indicates that these changes would increase ozone-forming nitrogen oxide pollution from heavy-duty trucks by 4.2% in 2030 and by 11.6% by 2055.

Katherine García, director of the Sierra Club's Clean Transportation for All campaign, commented on the potential impact. García stated, "Clean truck standards save lives." She added, "Weakening them would mean more toxic pollution in the air and more families paying the price with their health." The EPA proposal remains open for public comment.