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Regulatory

Announcement

 Printed on Recycled Paper

United States

Environmental Protection

Agency

Air and Radiation EPA 420-F-97-016

October 1997

Office of Mobile Sources

New Emission Standards For HeavyDuty Diesel Engines Used In Trucks

And Buses

The Environmental Protection Agency (EPA) is adopting a new

combined emission standard for oxides of nitrogen (NOx) and

hydrocarbons (HC) for model year 2004 and later heavy-duty diesel

engines used in trucks and buses. The new standard represents a 50

percent reduction in NOx from the 1998 and later model year NOx

standard, and will significantly assist states in meeting and maintaining

the ozone National Ambient Air Quality Standards.

What Are the Health and Environmental Benefits?

The new rule requires engines manufactured in 2004 and later model

years to have about a 50 percent lower NOx level compared to engines

meeting the 1998-2003 model year NOx standard. In 2020, EPA projects

a reduction of 1.1 million tons per year in ozone precursors due to the

new standard. In addition, the reduction in NOx emissions will also

result in a reduction of secondary nitrate particulate matter (PM) (which

forms in the atmosphere when NOx combines with ammonia) of about

43,000 tons per year.

NOx is a major contributor to the formation of ground-level ozone. The

new standard will benefit public health because ozone exposure causes a

range of human pulmonary and respiratory health effects, including chest

pain, coughing, and shortness of breath. In addition to ground-level

ozone, the secondary impacts of NOx include the formation of nitrate

PM, acid rain, and eutrophication of coastal waters. Therefore, reductions in NOx emissions will have considerable benefits to both public

health and the environment.
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How Much Will the Final Rule Cost?

EPA estimates a near term retail price increase of $260-$470 per vehicle,

with costs decreasing to half that amount in five years. The near term

increase represents a 2 to 4 percent increase in engine price and less than

one percent of the price of most new heavy-duty vehicles. EPA does not

expect any increase in fuel consumption due to the new rule. The long

term cost effectiveness of the final rule is estimated to be $100-$200 per

ton of NOx plus HC.

How Will the Rule Assist States?

The significant reduction in NOx emissions expected from the new

standard will assist the states in meeting the National Ambient Air

Quality Standards for ozone and PM. NOx emission inventories are

projected to rise by the early 2000s due to continued industrial growth

and expansion of motor vehicle usage. This is expected to result in a

significant increase in ground-level ozone and PM. Without further

controls, within the next 20 years mobile sources will contribute to about

half of all NOx emissions, with highway heavy-duty engines (HDEs)

representing about a quarter of these mobile source NOx emissions.

Therefore, further NOx control from HDEs on a national scale is seen as

a cost-effective strategy to control ozone levels especially where ozone

is high over a large region (as in the Midwest and Northeast).

How Does the Rule Provide Flexibility to Industry?

The final rule provides flexibility to the industry in three main areas:

• Manufacturers can certify their engines to either of two options;

• The time frame for this standard allows for the difficult technological

hurdles to be addressed without large increases in engine costs,

resulting in what EPA believes will be an extremely cost-effective way

of making necessary air quality gains; and

• The flexibility provided by averaging, banking, and trading (ABT)

lowers the costs to manufacturers and makes it easier to meet the

technical challenges of lower standards.
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In addition, engine manufacturers benefit from national emission standards because a single set of emission requirements applying to engines

in trucks and buses used anywhere in the country allows manufacturers

to achieve economies of scale and to concentrate research and development resources most effectively.

How Did This Initiative Evolve?

In response to the need for additional pollution reduction measures at the

national level, EPA held a series of discussions with the California Air

Resources Board (CARB) and representatives of the HDE manufacturing industry to exchange views on the appropriateness and feasibility of

new emission standards for HDEs. Based on these discussions, a historic

Statement of Principles (SOP) regarding highway HDEs was signed by

these parties in July 1995. EPA issued an Advance Notice of Proposed

Rulemaking (ANPRM) on August 31, 1995, which requested comment

on the SOP and the Agency’s plans to formally propose new HDE

emission standards consistent with the SOP. EPA formally proposed the

standard on June 27, 1996. During the comment period for the

rulemaking, stakeholders continued their strong support for the new

standards.

What are the Main Components of the Final Rule?

The standard is in the form of combined non-methane hydrocarbons

(NMHC) plus NOx and is presented in units of grams emitted per brake

horsepower-hour (g/bhp-hr). It applies to diesel engines manufactured

for model years 2004 and later. Manufacturers have the choice of certifying their engines to either:

2.4 g/bhp-hr NMHC + NOx or

2.5 g/bhp-hr NMHC + NOx with a limit of 0.5 g/bhp-hr on NMHC

EPA also proposed the above standard for gasoline-fueled engines, but is

not finalizing the standard at this time. The Agency is continuing to

evaluate new standards for gasoline-fueled engines and is planning a

supplemental rulemaking to address gasoline-fueled engines specifically.

EPA is adopting provisions to further encourage engine manufacturers to

use emission controls that will have a high degree of durability, and will

perform well in use without an unreasonable degree of owner involveEmission

Standard

In-Use

Emission

Controls
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ment. EPA is finalizing other basic provisions to help encourage the

maintenance and repair of emission controls after the end of regulatory

life is reached, and ensure emission controls are addressed properly

during engine rebuilding.

EPA is finalizing changes to the ABT provisions to enhance the feasibility and cost-effectiveness of the standards and encourage the early

introduction of cleaner engines, thus securing emission benefits earlier

than would otherwise be the case.

A technology review will be undertaken in 1999 to assess industry

progress and propose changes in the standards if necessary. The potential

role of fuels in achieving low HDE emissions is being evaluated now as

part of a technical working group comprised of representatives from

EPA, the engine manufacturers, the oil industry and other stakeholders.

The results of these technical evaluations will be considered as a part of

the 1999 technology review.

Does the New Standard Affect Trucks and Buses

Already on the Road?

No. The new standard and related provisions only apply to 2004 and

later model year engines.

How Can I Obtain a Copy of the Final Rule?

Additional information can be obtained electronically via the EPA

Internet server on the World Wide Web at:

http://www.epa.gov/OMSWWW

Information is also available by calling the NOx/ PM Heavy-Duty

Engine voice mailbox at: 313-741-7887

or by writing to:

U.S. Environmental Protection Agency

Office of Mobile Sources

Highway Heavy-Duty Team

2565 Plymouth Road

Ann Arbor, Michigan 48105

ABT

Provisions

Technology

Review