EPA proposes easing Biden-era truck emissions rules

The Environmental Protection Agency proposed on Thursday to ease Biden-era heavy-truck emissions rules, dialing back warranty and durability requirements for engines that were supposed to get cleaner starting with model year 2027. The change would let some engines stay on the market even if they do not meet the tougher tailpipe limits slated to phase in, a shift that puts truckers, fleet operators and communities along freight corridors at the center of a fight over diesel pollution and compliance costs.

The proposal does not scrap the 2023 rule. Instead, it would scale back emissions warranty obligations and give manufacturers more time before longer regulatory useful-life standards take effect, while keeping current products in circulation as newer engines are developed. That is a direct rewrite of the January 24, 2023 rule, which updated test procedures, regulatory useful life, emission-related warranty and other requirements for heavy-duty engines and vehicles. The rule was designed to reduce ozone- and particulate-matter-forming pollution from one of the transportation sector’s biggest sources of emissions.

The 2023 standards were projected to deliver large public-health gains by 2045. EPA projected they could prevent up to 2,900 premature deaths a year, avoid 6,700 hospital admissions and emergency department visits, and cut 18,000 childhood asthma cases. It also projected 3.1 million fewer asthma and allergic-rhinitis symptom cases, 78,000 fewer lost work days, 1.1 million fewer lost school days and $29 billion in annual net benefits. The rule would make the standards more than 80 percent stronger than the existing requirements, increase useful life by 1.5 to 2.5 times and lengthen emissions warranties by 2.8 to 4.5 times.

Industry pressure for delay had been building for months. The American Trucking Associations and other groups asked EPA in 2025 to push implementation of the NOx rule to 2031, arguing that the timetable carried heavy compliance costs and operational burdens. The separate Phase 3 greenhouse-gas standards for heavy-duty vehicles, finalized on March 29, 2024, also begin phasing in with model year 2027 for vocational vehicles and tractors.

The Sierra Club warned that weakening the standards could worsen asthma attacks, heart disease, premature deaths and missed work and school days.