Coming soon: a proposal to weaken protections against dangerous pollution from buses and trucks

The Trump EPA is expected to soon propose a rule that would weaken protections against pollution that poses serious dangers to people’s health from heavy-duty vehicles – like transit and school buses, delivery trucks, garbage trucks, and long-haul semi-trucks.

Despite the fact they are only 5% of the vehicles on America’s roads, heavy-duty vehicles are the largest source of ozone-forming NOx pollution (the main component of smog) of all transportation sources. They also contribute significantly to other dangerous types of pollution, including carbon monoxide, fine particulate pollution, volatile organic compounds (VOCs), and air toxics. 

In 2022, EPA finalized more protective standards for NOx pollution from heavy-duty vehicles, beginning with model year 2027. It was the first major update to national heavy-duty vehicle standards to reduce this pollution in more than 20 years. 

But now the Trump EPA is expected to undermine those more protective standards by removing provisions that ensure emission controls are maintained properly throughout the life of an engine. Since 2010, EPA standards to reduce this harmful pollution have included incentives to ensure sound operational practices. Reporting has also suggested that EPA will propose to weaken the 2022 rule’s warranty provisions, which help to ensure that, as engines age, they continue to meet the pollution standards that protect people’s health. EPA’s proposal could remove these widely deployed good practices and important assurances, resulting in more pollution, health harms, and higher costs.  

Here are some more things you should know:  

Pollution from heavy-duty vehicles threatens public health  

The pollution from trucks, buses and other heavy-duty vehicles are linked to severe health harms including:

• Asthma and other respiratory diseases - NOx and VOCs create ground-level ozone, which forms smog and is a powerful lung irritant. Fine particulate matter, particularly diesel exhaust, penetrates deep into the lungs, triggering asthma attacks, bronchitis, and permanently impairing lung development in children.
• Heart disease and preventable early death – fine particulate matter is directly linked to heart attacks, strokes, and premature death.
• People who live near transportation corridors, ports and warehouses are most at risk –EPA estimates 72 million people live within 200 meters of a truck freight route. Often these are low-income communities and communities of color.
• Children, older adults, and people with preexisting conditions are more vulnerable to the harmful effects of heavy-duty vehicle pollution. 

Manufactures are already meeting the more protective NOx standards for heavy-duty vehicles 

All leading heavy-duty engine and vehicle manufacturers have announced they have engines ready to meet the 2027 NOx standards.

The standards can be met through improvements to internal combustion engines and catalyst systems that clean up exhaust. That may mean using cylinder deactivation, selective catalytic reduction systems, closed crankcase, and/or improved systems that cleanup exhaust gases.

In January 2026, Traton’s International unveiled plans for its integrated powertrain designed to comply with EPA’s 2027 emissions standards. Soon after, Daimler, Cummins, Volvo and PACCAR all announced EPA 2027 compliant engines as well. 

The latest in a series of actions that weaken protections from vehicle pollution 

EPA’s anticipated proposal is part of a broader set of actions the administration has taken to substantially weaken commonsense protections for vehicles, thus increasing pollution and health risks, and raising costs for Americans. 

Today, EDF and our partners will be submitting extensive comments vigorously opposing EPA’s proposed delay of air pollution safeguards for new light-duty vehicles – which include cars, SUVs and passenger trucks. EDF and a broad range of stakeholders including states, cities, public health, business and labor interests – have also filed legal challenges to EPA’s damaging repeal of the Endangerment Finding and all motor vehicle greenhouse gas emission standards.