Coming Soon: Trump EPA Expected to Delay “Tier 4” Air Pollution Standards for Cars and Trucks

As early as this week, the Trump EPA is expected to propose delaying vital health protections against harmful air pollution from new cars, trucks and SUVs – pollution that causes serious heart and lung diseases and early deaths. 

The protections in jeopardy are the 2024 “Tier 4” emissions standards, which reduce smog-forming nitrogen oxides (NOx), fine particulate matter (PM 2.5) and volatile organic compounds (VOCs) from new light and medium-duty vehicles in model years 2027 to 2032.  

News reports have suggested that EPA will issue a two-year delay of the standards now, and then later issue a broader weakening of these protections as well as weakening standards for heavy-duty vehicles like freight trucks and buses that were finalized in 2022. Weakening and delaying these vital protections will mean more pollution, more harm, and higher costs for families.

Here are some things you should know: 

Tailpipe pollution from cars and trucks is a serious threat to public health 

Tailpipe emissions are a significant source of air pollutants that are linked to serious illnesses and premature deaths.  

• Asthma and other lung diseases: Tailpipe pollutants form smog, which is a powerful lung irritant. Fine particulate matter, particularly from diesel exhaust, penetrates deep into the lungs and triggers asthma attacks and bronchitis. It can permanently impair lung development in children.
• Heart disease and Early Death:  Fine particulate matter is directly linked to heart attacks, strokes, and premature death.
• Communities near major transportation corridors, ports, and warehouses and children, older adults, and people with pre-existing conditions are more vulnerable to the harmful effects of tailpipe pollution.  

Strong vehicle standards are one of the most effective tools to reduce all these harms.  

Americans will pay for this delay with their lives, their health, and their pocketbooks

EDF estimates that full repeal of the Tier 4 standards would result in more than $140 billion in health costs to the nation through 2055. Delaying these standards for two years will result in tens of billions of dollars in health costs and many hundreds of premature deaths. Delaying and weakening these protections will mean higher healthcare costs, lower worker productivity, and damage to local economies.  

The “Tier 4” standards are readily achievable using commonsense, low-cost tech technologies that are already being deployed on many vehicles

The standards the Trump EPA is expected to weaken can be met through readily available improvements in internal combustion engine technologies. Electrification technologies can also provide a cost-effective compliance pathway. 

• The particulate matter standard can be met through the installation of a gasoline particulate filter, a cost-effective mature technology that has been in use globally for more than a decade. The incremental direct cost of these filters represents less than one percent of a vehicle’s price. A number of 2026 cars and passenger trucks already include them, including models from Ford, BMW and VW, with an additional 50+ more models expected in 2027.
• The VOC and NOx standards can also be met through existing internal combustion engine technology. Certification data from 2024 through 2026 vehicles showed that about one-quarter of the carlines in the U.S. already tested below the new light-duty standard and many tested below the new medium-duty standard.
• Flexibilities make the standards even more feasible in the near-term. To provide manufacturers with additional time to adjust product plans and apply technologies to vehicles, EPA finalized gradual phase-ins for each standard. After considering comments from automakers, EPA finalized a slower phase-in than originally proposed.