EPA Announces the "Clean
Trucks Plan"
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Heavy-duty trucks and buses continue to contribute significantly
to air pollution at the local, regional, and national level, often
disproportionally affecting communities of color and low-income
populations.
To ensure the progress needed on cleaning trucks and buses and to
harness improvements in vehicle technologies, EPA will issue two major
regulations over the next three years—the "Clean Trucks Plan" that will
result in decreasing emissions from new heavy-duty vehicles, including
long-haul tractors, buses, commercial delivery trucks, and many other
types of trucks. These new rules will be major steps towards improving
air quality and addressing the climate crisis.
EPA's Clean Trucks Plan
The Agency is working on the following actions over the next three years.
By December 2022, EPA will propose and finalize new stringent emissions standards to
reduce nitrogen oxides (NOx) pollution from trucks starting in model year 2027. This
action will include an update of current greenhouse gas (GHG) standards to capture
market shifts to zero-emission technologies in certain segments of the heavy-duty
vehicle sector.
EPA is also working on new stringent GHG emissions standards for heavy-duty engines
and vehicles starting as soon as model year 2030.
Taken together, these new multi-pollutant standards will improve public health in
our communities and set the U.S. on a course to achieve ambitious levels of GHG
emissions reductions from commercial highway transportation over the long term.
EPA looks forward to working with all stakeholders as we move forward with these plans.
United States
Environmental Protection
Agency
Office of Transportation and Air Quality
EPA-420-F-21-057
August 2021

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Air Quality and Health Impacts of Heavy-Duty Vehicles
Pollution from heavy-duty trucks contributes to poor air quality and health across the country,
especially in overburdened and underserved communities. Heavy-duty vehicles are the largest
contributor (about 32%) to mobile source emissions of NOx, which react in the atmosphere to
form ozone and particulate matter (PM). These pollutants are linked to respiratory and/or cardio-
vascular problems and other adverse health impacts that lead to increased medication use, hospital
admissions, emergency department visits, and premature deaths.
Mobile Source NOx (2017)
0.2%
13.6%	//
32.1%
i Onroad LD Gasoline
i Onroad LD Diesel
i Onroad HD Gasoline
i Onroad HD Diesel
¦	Nonroad Gasoline
i Nonroad Diesel
i Commerical Marine Vessels
¦	Locomotives
i Aircraft

Sources: MOVES3 for onroad and nonroad and 2017 National Emissions Inventory (NEI) for all other mobile
sectors.
In addition, pollution from trucks directly affects people who live near roads and other areas of
high truck activity like ports. Populations who live, work, or go to school near high-traffic roadways
experience higher rates of numerous adverse health effects, and there is substantial evidence that
people who live or attend school near major roadways are more likely to be low-income or people
of color. NOx pollution from heavy-duty vehicles also impairs visibility and causes damage to ter-
restrial and aquatic ecosystems.
Heavy-Duty Vehicles and Climate Change
Transportation is the largest source of GHG emissions in the United States, making up 29 per-
cent of all emissions. Within the transportation sector, heavy-duty vehicles are the second-largest
contributor, at 23 percent. Reducing GHG emissions is a critical step in reducing the probability
of impacts from climate change, including heat waves, drought, sea level rise, extreme climate and
weather events, coastal flooding, and wildfires. Some populations may be especially vulnerable to
damages associated with climate change, such as the very young, the elderly, low-income people,
the disabled, people of color, and indigenous populations.

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Mobile Source GHGs (2019)
All Other
Transportation
Sources
5% ,
Light-Duty
Vehicles
58%
Rail
2%
Ships and
Boats
2%
Medium-and
Heavy-Duty
Trucks
23%
Aircraft
10%
Source: "Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2019," EPA 430-R-21-005.
EPA previously took action to reduce GHG emissions from heavy-duty trucks with its Phase 1 and
Phase 2 GHG standards. The Phase 2 standards began in model year 2021, with two additional
steps of increasing stringency that will take effect in model years 2024 and 2027. The Phase 2
program promotes a new generation of cleaner, more fuel-efficient gasoline and diesel trucks.
Opportunities for Significant Emissions Reductions from Heavy Duty
Trucks: The Clean Trucks Plan
By December 2022, EPA will finalize a new standard for NOx emissions from heavy duty trucks start-
ing with model year 2027. In this action, the agency will also explore updates to the Phase 2 GHG
standards for certain heavy-duty fleets that are rapidly shifting toward zero-emission technologies.
EPA last revised the NOx standards: for on-highway heavy-duty trucks and engines in 2001—more
than 20 years ago. Although those standards achieved important NOx reductions, new technolo-
gies available today can help achieve the additional reductions we need to improve air quality and
health in our communities.
Many state and local agencies across the country have asked the EPA to issue regulations that further
reduce NOx emissions from heavy-duty trucks in order to protect the health of their communities.
Such reductions are a critical part of many areas' strategies to attain and maintain the health-based
air quality standards, and to ensure that all communities benefit from improvements in air quality.
One area where technologies can improve emission outcomes relates to trucks Operating at what
are known as "low loads." EPA's analysis of trucking emissions has shown that current NOx con-
trols are not effective under certain low-load operating conditions, such as when trucks idle, move

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slowly, or operate in stop-and-go traffic. Emission control technologies that can help reduce NOx
emissions under low-load conditions now exist, and they represent one area where EPA intends to
focus as it develops a new NOx regulation.
Beyond such low-load NOx reduction technologies, the trucking sector has also seen advances in
zero-emission technologies. In recent years, zero-emission heavy-duty trucks have begun entering
the market in volumes that were not foreseen when EPA began the Phase 2 GHG program. Many
of these zero-emission technologies are available today, and the number of products available, as
well as production volumes, are expected to accelerate in the next few years. EPA will assess the
impact that these zero-emission technologies will have on the overall effectiveness of the Phase 2
program and whether targeted adjustments to GHG standards in 2027 may be warranted.
Beyond 2027, heavy-duty truck manufacturers are already signaling a large-scale migration from
gasoline and diesel engines to zero-emission technologies in their products. EPA is also working on
revising GHG standards for all heavy-duty vehicles and engines. These standards would begin as
soon as model year 2030.
For More Information
For more information on these actions, please contact the U.S. Environmental Protection Agency,
Office of Transportation and Air Quality through our webpage at: https://www.epa.gov/transportation-
air-pollution-and-climate-change/forms/contact-us-about-transportation-air-pollution.

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