Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33421

controls emissions from an individual

enclosed storage bin, stack emissions

which exhibit greater than 7 percent

opacity.

(g) Owners or operators of multiple

storage bins with combined stack

emissions shall comply with the

emission limits in paragraph (a) of this

section.

5. It is proposed to amend § 60.675 by

revising paragraph (d) and adding

paragraph (g) to read as follows:

§ 60.675 Test methods and procedures.

* * * * *

(d) When determining compliance

with the fugitive emissions standard for

any affected facility described under

§ 60.672(b) and where there are no

individual readings greater than 10%

opacity and where there are no more

than 3 readings of 10% opacity for the

first hour of testing of this affected

facility and the opacity of stack

emissions from any baghouse that only

controls emissions from an individual,

enclosed storage bin under § 60.672(f),

using Method 9, the duration of the

Method 9 observations shall be 1 hour

(10 6-minute averages).

* * * * *

(g) If, after 30 days notice for an

initially scheduled performance test,

there is a delay (due to operational

problems, etc.) in conducting any

rescheduled performance test required

in this section, the owner or operator of

an affected facility shall submit to the

Administrator at least 7 days prior

notice of any rescheduled performance

test.

6. Section 60.676 is amended by

removing and reserving paragraph (b),

revising paragraph (f), redesignating

paragraph (g) as paragraph (j) and

revising newly designated (j), and

adding new paragraphs (g), (h), and (i)

to read as follows:

§ 60.676 Reporting and recordkeeping.

* * * * *

(b) [reserved]

* * * * *

(f) The owner or operator of any

affected facility shall submit written

reports of the results of all performance

tests conducted to demonstrate

compliance with the standards set forth

in § 60.672, including reports of opacity

observations made using Method 9 to

demonstrate compliance with § 60.672

(b), (c), and (f), and reports of

observations using Method 22 to

demonstrate compliance with

§ 60.672(e).

(g) The owner or operator of any wet

screening operation and associated

conveyor shall keep a record describing

the location of these operations and

shall submit an initial report describing

the location of these operations within

30 days. If, subsequent to the initial

report, any screening operation ceases to

operate as wet screening, the owner or

operator shall submit a report of this

change and shall immediately comply

with all of the requirements of the

regulation for an affected facility. These

reports shall be submitted within 30

days following such change.

(h) The Subpart A requirement under

§ 60.7(a)(2) for notification of the

anticipated date of initial startup of an

affected facility shall be waived for

owners or operators of affected facilities

regulated under this subpart.

(i) A notification of the actual date of

initial startup of each affected facility

shall be submitted to the Administrator.

For a combination of affected facilities

in a production line that begin actual

initial startup on the same day, a single

notification of startup may be submitted

by the owner or operator to the

Administrator. The notification shall be

postmarked within 15 days after such

date and shall include a description of

each affected facility, equipment

manufacturer, and serial number of the

equipment, if available.

(j) The requirements of this section

remain in force until and unless the

Agency, in delegating enforcement

authority to a State under section 111 of

the Act, approves reporting

requirements or an alternative means of

compliance surveillance adopted by

such States. In that event, affected

facilities within the State will be

relieved of the obligation to comply

with the reporting requirements of this

section, provided that they comply with

requirements established by the State.

[FR Doc. 96–16012 Filed 6–26–96; 8:45 am]

BILLING CODE 6560–50–P

40 CFR Part 86

[AMS-FRL–5526–9]

Control of Emissions of Air Pollution

from Highway Heavy-Duty Engines

AGENCY: Environmental Protection

Agency (EPA).

ACTION: Notice of proposed rulemaking.

SUMMARY: In this action, EPA proposes

new emission standards and related

provisions for heavy-duty engines

intended for highway operation,

beginning in the 2004 model year. The

proposed provisions represent a large

reduction (approximately 50 percent) in

emission of oxides of nitrogen (NOX), as

well as reductions in hydrocarbons (HC)

and nitrate particulate matter (PM) from

trucks and buses. If the proposed

standards are implemented, the

resulting emission reductions would

translate into significant, long-term

improvements in air quality in many

areas of the U.S. This would provide

much-needed assistance to a range of

states and regions facing ozone and

particulate air quality problems that are

causing a range of adverse health effects

for their citizens, especially in terms of

respiratory impairment and related

illnesses.

EPA is also proposing several

provisions to increase the durability of

emission controls and to provide

flexibility for manufacturers in

complying with the stringent new

standards. The Agency previously

published an Advance Notice of

Proposed Rulemaking relating to this

action and addresses here a number of

the comments received on the Advance

Notice. EPA believes the proposed

program would result in significant

progress throughout the country in

protecting public health and the

environment.

DATES: EPA requests comment on the

proposal rulemaking no later than

August 26, 1996.

EPA will hold a public hearing on this

proposal on July 25, 1996.

EPA will also hold a public meeting

on July 19, 1996, to discuss the

proposed HDE regulations and receive

informal public input on them, and to

discuss other potential mobile source

controls identified in the California

Ozone State Implementation Plan for

the South Coast (the greater Los Angeles

area).

More information about commenting

on this action and on the public hearing

and meeting may be found under Public

Participation, in Section II of

SUPPLEMENARY INFORMATION.

ADDRESSES: Materials relevant to this

proposal including the draft regulatory

text and Regulatory Impact Analysis

(RIA) are contained in Public Docket A–

95–27, located at room M–1500,

Waterside Mall (ground floor), U.S.

Environmental Protection Agency, 401

M Street, S.W., Washington, DC 20460.

The docket may be inspected from 8:00

a.m. until 5:30 p.m., Monday through

Friday. A reasonable fee may be charged

by EPA for copying docket materials.

Comments on this proposal should be

sent to Public Docket A–95–27 at the

above address. EPA requests that a copy

of comments also be sent to Chris

Lieske, U.S. EPA, Engine Programs and

Compliance Division, 2565 Plymouth

Road, Ann Arbor, MI 48105.

The hearing on this proposal will be

held at the Marriott Hotel and
33422 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

1See 42 U.S.C. 7401 et seq. 2 VOCs consist mostly of hydrocarbons (HC).

3The CAA limits the role states may play in

regulating emissions from new motor vehicles.

California is permitted to establish emission control

standards for new motor vehicles, and other states

may adopt California’s programs (Sections 209 and

177 of the Act).

4Highway heavy-duty engines, sometimes

referred to as highway HDEs in this proposal, are

used in heavy-duty vehicles, which EPA defines as

highway vehicles with a gross vehicle weight rating

over 8,500 pounds.

Conference Center, 1275 South Huron

Street, Ypsilanti, MI, (313) 487–2000,

from 9:00 am until all testimony has

been presented.

The public meeting to discuss the

proposed HDE regulations will be held

Downtown Los Angeles Hyatt Regency,

711 South Hope Street, Los Angeles,

California. The public meeting will be

conducted in two sessions beginning at

2:00 p.m. and 7:00 p.m., with a dinner

recess before the 7:00 p.m. sessions.

This proposal, the draft regulatory

text, and the draft Regulatory Impact

Analysis (RIA) are available

electronically and can be obtained on

the Technology Transfer Network

(TTN), which is an electronic bulletin

board system (BBS) operated by EPA’s

Office of Air Quality Planning and

Standards and via the internet. Details

on how to access TTNBBS and the

internet are included in Section XIII of

SUPPLEMENTARY INFORMATION.

FOR FURTHER INFORMATION CONTACT:

Chris Lieske, U.S. EPA, Engine

Programs and Compliance Division,

(313) 668–4584.

SUPPLEMENTARY INFORMATION:

I. Introduction

Air pollution continues to represent a

serious threat to the health and wellbeing of millions of Americans and a

large burden to the U.S. economy. This

threat exists despite the fact that, over

the past two decades, great progress has

been made at the local, state and

national levels in controlling emissions

from many sources of air pollution. As

a result of this progress, many

individual emission sources, both

stationary and mobile, pollute at only a

fraction of their precontrol rates.

However, continued industrial growth

and expansion of motor vehicle usage

threaten to reverse these past

achievements. Today, more than five

years after passage of major

amendments to the Clean Air Act (CAA

or the Act), many states are still finding

it difficult to meet the ozone and PM

National Ambient Air Quality Standards

(NAAQSs) by the deadlines established

in the Act.1 Furthermore, other states

which are approaching or have reached

attainment of the ozone and PM

NAAQSs will likely see those gains lost

if current trends persist.

In recent years, significant efforts

have been made on both a national and

state level to reduce air quality

problems associated with ground-level

ozone, with a focus on its main

precursors, oxides of nitrogen (NOX)

and volatile organic compounds

(VOCs).2 In addition, airborne

particulate matter (PM) has been a major

air quality concern in many regions. As

discussed below, NOX, ozone, and PM

have all been linked to a range of

serious respiratory health problems and

a variety of adverse environmental

effects.

NOX control is now seen as a critical

strategy to control ozone levels, which

remain unacceptably high in many areas

across the country. For many years,

control of VOCs was the main strategy

employed in efforts to reduce groundlevel ozone. VOC reductions were

deemed more cost effective (on a per-ton

basis) and more readily achievable than

NOX reductions. In addition, it was

generally believed that greater ozone

benefits could be achieved through VOC

reductions. More recently, it has become

clear that NOX controls are often an

effective strategy for reducing ozone

where its levels are high over a large

region (as in the Midwest and

Northeast). As a result, attention has

turned to controlling NOX emissions as

a key to improving air quality in many

areas of the country.

Current projections show total NOX

emissions decreasing slightly during the

next few years as stationary and mobile

source control programs promulgated

under the 1990 CAA amendments are

phased in. However, the downward

trends in NOX pollution will begin to

reverse and NOX emission inventories

will begin to rise by the early or middle

part of the next decade due to growth in

stationary and mobile source activity. In

this timeframe, emissions from mobile

sources will account for about half of all

NOX emissions and heavy-duty vehicles

are projected to represent about one

quarter of mobile source NOX emissions.

In most areas, a significant increase in

ground-level ozone is expected to

accompany the rise in NOX emissions.

Levels of PM are also expected to rise,

both because of the expected increase in

numbers of PM sources and because

NOX is transformed in the atmosphere

into fine nitrate particles that account

for a substantial fraction of the airborne

particulate in some areas of the country

(a process called ‘‘secondary particulate

formation’’). Given these expected

trends and the absence of new emission

control initiatives, the Agency believes

that some of the nation’s hard-won air

quality improvements will begin to be

seriously threatened early in the next

decade.

Over the past decade, ambient air

measurements and computer modeling

studies have repeatedly demonstrated

that ozone is a regional-scale issue, not

just a local issue, in part because ozone

and its precursors, NOX and VOC, are

often transported across large distances.

Thus, there is a role for all levels of

government to address these issues.

EPA’s state and local partners generally

agree that only with new initiatives at

the regional and national level can longterm clean air goals be achieved.

The states have jurisdiction to

implement a variety of stationary source

emission controls. In most regions of the

country, states are implementing

significant stationary source NOX

controls (as well as stationary source

VOC controls) for controlling acid rain,

ozone, or both. In many areas, however,

these controls will not be sufficient to

reach and maintain the ozone standard

without significant additional NOX

reductions from mobile sources.

Generally, the Clean Air Act specifies

that standards for controlling NOX, HC,

and PM emissions from new motor

vehicles must be established at the

federal level.3 Thus, the states look to

the national mobile source emission

control program as a complement to

their efforts to meet air quality goals.

The concept of common emission

standards for mobile sources across the

nation is strongly supported by

manufacturers, which often face serious

production inefficiencies when different

requirements apply to engines or

vehicles sold in different states or areas.

Motor vehicle emission control

programs have a history of technological

success that, in the past, has largely

offset the pressure from constantly

growing numbers of vehicles and miles

traveled in the U.S. The per-vehicle rate

of emissions from new passenger cars

and light trucks has been reduced to

very low levels. As a result, increasing

attention is now focused on heavy-duty

trucks (ranging from large pickups to

tractor-trailers), buses, and nonroad

equipment.

Since the 1970s, manufacturers of

heavy-duty engines for highway use

have developed new technological

approaches in response to periodic

increases in the stringency of emission

standards.4 However, the technological

characteristics of heavy-duty engines,

particularly diesel engines, have so far

prevented achievement of emission

levels comparable to today’s light-duty
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33423

5 Information cited in this section and other

related information on health and environmental

effects related to NOX and VOC are available from

the Regulatory Impact Analysis and other

documents found in Docket A–95–27.

6Air Quality Criteria Document for Oxides of

Nitrogen, EPA–600/8–91/049aF–cF, August 1993

(NTIS #: PB92–17–6361/REB, –6379/REB, –6387/

REB).

gasoline vehicles. While diesel engines

provide advantages in terms of fuel

efficiency, reliability, and durability,

controlling NOX emissions is a greater

challenge for diesel engines than for

gasoline engines. Similarly, control of

PM emissions, which are very low for

gasoline engines, represents a

substantial challenge for diesel engines.

Part of this challenge is that most

traditional NOX control approaches tend

to increase PM, and vice versa.

Despite these technological

challenges, there is substantial evidence

of the ability for heavy-duty highway

engines to achieve significant additional

emission reductions. In their successful

efforts to reach lower NOX and PM

levels over the past 20 years, heavy-duty

highway diesel engine manufacturers

have identified new technologies and

approaches that offer promise for

significant new reductions. New

technological options are available to

manufacturers of heavy-duty gasoline

engines as well. The emerging

technological potential for much cleaner

heavy-duty vehicles is discussed further

in Section IV of this proposal and in the

associated Regulatory Impact Analysis

(RIA).

Recognizing the need for additional

NOX and PM control measures to

address air quality concerns in several

parts of the country and the growing

contribution of the heavy-duty engine

sector to ozone and PM problems, EPA

issued an Advance Notice of Proposed

Rulemaking (ANPRM) on August 31,

1995. In the ANPRM, the Agency sought

early comment on the general

framework of a program to reduce

emissions from the heavy-duty engine

category. The Agency has been pleased

that a broad range of interested parties

have responded to the ANPRM with

their comments. To the extent possible,

EPA has considered and addressed

these comments in the preparation of

this Notice of Proposed Rulemaking

(NPRM). EPA continues to encourage

comment on all aspects of the proposed

program; where ANPRM commenters

may believe that this action fails to

address their comments, EPA

encourages them to resubmit those

comments in the context of this formal

proposal.

This preamble is organized as follows:

Section II.A. summarizes the public

health and environmental concerns

from ozone, PM and their precursors;

Section II.B. discusses the connection of

these emissions to air quality trends and

the regional nature of the ozone and PM

problems; Section II.C. presents trends

in overall nationwide NOX, VOC, and

PM emissions; Section II.D. presents the

current and projected future

contribution of heavy-duty vehicles to

overall emissions; Section II.E.

summarizes the overall rationale for the

action being proposed; Section III. then

describes in detail the standards and

other provisions being proposed as well

as background on the regulation of

highway heavy-duty engines; Section

IV. summarizes the technological

feasibility of the proposed program;

Section V. reviews the results of EPA’s

economic and environmental analyses;

Section VI. discusses the potential role

of several incentive-based programs;

and Section VII. provides information

about the formal public comment

process, including a public hearing. The

actual proposed regulatory language is

available in the public docket and

electronically (see ADDRESSES above and

Section XIII. for further information).

II. Need for New NOX and VOC

Emission Control

A. Health and Environmental Impacts of

Ambient NOX and VOC: Ozone,

Particulate Matter, and Other Effects

Oxides of nitrogen (NOX) comprise a

family of highly reactive gaseous

compounds that contribute to air

pollution in both urban and rural

environments. NOX emissions are

produced during the combustion of

fuels at high temperatures. The primary

sources of atmospheric NOX include

both stationary sources (such as power

plants and industrial boilers), highway

sources (such as light-duty and heavyduty vehicles) and nonroad sources

(such as construction and agricultural

equipment). Ambient levels of NOX can

be directly harmful to human health and

the environment. More importantly

from an overall health and welfare

perspective, NOX contributes to the

production of secondary chemical

products that in turn cause additional

health and welfare effects. Prominent

among these are ozone and secondary

PM formation. Each of these phenomena

is briefly discussed in this proposal and

in more detail in the Regulatory Impact

Analysis.

Much of the evaluation of the health

and environmental effects related to

NOX found in this section and in the

Regulatory Impact Analysis (RIA) were

also discussed in the August 31, 1995

ANPRM.5 EPA encourages comment on

the Agency beliefs expressed in this

proposal and in the RIA.

1. Direct Health Effects of NOX

The component of NOX that is of most

concern from a health standpoint is

nitrogen dioxide, NO2. EPA has set a

primary (health-related) NAAQS for

NO2 of 100 micrograms per cubic meter,

or 0.053 parts per million. Direct

exposure to NO2 can reduce breathing

efficiency and increase lung and airway

irritation in healthy people, as well as

in the elderly and in people with preexisting pulmonary conditions.

Exposure to NO2 at or near the level of

the ambient standard appears to

increase symptoms of respiratory

illness, lung congestion, wheeze, and

increased bronchitis in children.6

2. Indirect Health and Welfare Effects of

NOX and VOC

In addition to the direct effects of

NOX, the chemical transformation

products of NOX also contribute to

adverse health and environmental

impacts. These secondary impacts of

NOX include ground-level ozone, nitrate

particulate matter, acid deposition,

eutrophication (plant overgrowth) of

coastal waters, and transformation of

other pollutants into more dangerous

chemical forms. Each of these is

discussed below and in the Regulatory

Impact Analysis. Also, volatile organic

compounds (VOCs), composed of a very

large number of different hydrocarbons

(HC) and other organic compounds, are

primary precursors to ozone. The health

and environmental effects of these

compounds as a class are generally

considered in terms of their effect on

ozone and are discussed below and in

the RIA. Health or other effects of

individual toxic compounds are not

separately addressed in this proposal.

a. Ozone

NOX and VOCs are primary

precursors to ground level ozone (O3).

As discussed later in this proposal,

ozone tends to be a regional

phenomenon in which elevated levels of

ozone can develop over wide areas.

Ozone is a highly reactive chemical

compound that can affect both

biological tissues and man-made

materials. Ozone exposure causes a

range of human pulmonary and

respiratory health effects. While ozone’s

effects on the pulmonary function of

sensitive individuals or populations

(e.g., asthmatics) are of primary concern,

evidence indicates that high ambient

levels of ozone can cause respiratory

symptoms in healthy adults and
33424 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

7Air Quality Criteria Document for Ozone and

Related Photochemical Oxidants (External Review

Draft), EPA/600/P–93/004aF-cF, 1996.

8 Gross, K.B., White, H.J. (1987) ‘‘Functional and

pathologic consequences of a 52-week exposure to

0.5 PPM ozone followed by a clean air recovery

period,’’ Lung 165:283–295.; Huang, Y, Chang, L.-

Y, Miller, F.J., Crapo, J.D. (1988) ‘‘Lung injury

caused by ambient levels of ozone,’’ J. Aerosol Med.

1:180–183; Tyler, W.S., Tyler, N.K., Last, J.A.,

Gillespie, M.J., Barstow, T.J. (1988) ‘‘Comparison of

daily and seasonal exposures of young monkeys to

ozone,’’ Toxicology 50:131–144.

9See, for example, Euler, G.L.; Abbey, D.E.;

Hodgkin, J.E.; Magie, A.R. (1988) ‘‘COPD symptom

effects of long-term cumulative exposure to ambient

levels of total oxidants and nitrogen dioxide in

California Seventh-Day Adventist residents,’’ Arch.

Environ. Health 43:279–285.

10Air Quality Criteria for Particulate Matter

(External Review Draft), EPA–600/AP–95/001a–a,

April 1995.

children as well. For example, exposure

to ozone for several hours at moderate

concentrations, especially during

outdoor work and exercise, has been

found to decrease lung function,

increase airway inflammation, increase

sensitivity to other irritants, and impair

lung defenses against infections in

otherwise healthy adults and children.

Other symptoms include chest pain,

coughing, and shortness of breath.7

Recent studies focusing on chronic

lung effects are also being evaluated as

part of EPA’s review of the current

ozone NAAQS. Repeated exposures in

laboratory animals suggest a cumulative

impact, potentially causing permanent

structural changes to respiratory

tissues.8 Extrapolation of these results to

humans raises concern that individuals

who have been exposed to ambient air

containing high levels of ozone each

summer of their lives may experience a

reduced quality of life in their later

years.9

As described in more detail in the

RIA, the presence of elevated levels of

ozone is of concern in rural areas as

well. Because of its high chemical

reactivity, ozone causes injury to

vegetation. This injury has been

observed at ozone levels above and also

below the current ozone NAAQS; EPA

in is the process of reconsidering the

appropriate level of the ozone NAAQS

in light of such evidence. Although the

action proposed is not being proposed

for the purpose of reducing crop damage

from ozone, it is of interest to note that

estimates based on experimental studies

of the major commercial crops in the

U.S. suggest that ozone may be

responsible for significant agricultural

crop yield losses. In addition, ozone

causes noticeable leaf injury in many

crops, which reduces their marketability

and value. Finally, there is evidence

that exposure to ambient levels of ozone

existing in many parts of the country

may be responsible for forest and

ecosystem damage. Such damage may

be exhibited as leaf damage, reduced

growth rate, and increased susceptibility

to insects, disease, and other

environmental stresses.

b. Nitrate Particulate Matter

The conversion of NOX into fine

particulate matter (such as ammonium

nitrate) is of significant human health

and environmental concern. In general,

air pollutants collectively called

particulate matter (PM) are divided into

primary and secondary sources. Primary

sources include dust, dirt, soot, smoke,

and liquid droplets directly emitted into

the air by sources such as factories,

power plants, cars, trucks, woodstoves/

fireplaces, construction activity, forest

fires, agricultural activities such as

tillage, and natural windblown dust.

Particles formed secondarily in the

atmosphere by condensation or the

transformation of emitted gases such as

SO2, NOX, and VOCs are also

considered particulate matter. Ambient

PM is related to several adverse health

and environmental effects.

At the present time, data is not

available to precisely partition PM–10

into its primary and secondary PM

components. Most of the well developed

nationwide PM–10 inventories are

based only on primary sources, but

inventories for some PM–10

nonattainment areas have identified the

primary and secondary PM. From the

available data, it is clear that the roles

of primary and secondary PM vary

geographically. For example,

ammonium nitrate is a significant

portion of the PM–10 inventory in cities

in the western states (e.g., Denver, Salt

Lake City, Los Angeles) and a smaller

portion of total PM in cities in the

eastern states (e.g., Philadelphia, New

York). As discussed in the RIA, EPA

estimates that the NOX to Nitrate

conversion rate varies from near zero to

about 20 percent, with a U.S. average in

the order of about 5 percent. While there

is not data available on this at the

present time, it is reasonable to assume

that NOX emissions from heavy-duty

engines are converted to nitrate at the

same rate as NOX from other sources.

The existing NAAQS for particulate

matter were set in 1987. The primary

standards, intended to protect human

health, are an average concentration of

150 micrograms per cubic meter (μg/m3)

over a 24-hour period and an average

concentration of 50 μg/m3 annually.

PM–10 was selected as the indicator for

particle pollution based on lung

deposition studies. PM–10 includes all

particles in the size range of 10

micrometers or less. Particles smaller

than 2.5 micrometers are capable of

penetrating deeper into the lungs and

air sacs. The secondary standards,

intended to protect against damage to

the environment, were set identical to

the primary standards.

Since the last review of the PM–10

NAAQS in 1987, many epidemiological

studies of PM–10 exposure at levels

below the existing 24-hour and annual

standards have associated higher levels

of particle pollution with increased

occurrence of illness and death (e.g.,

increased hospital admissions,

aggravation of bronchitis and asthma,

and premature deaths). Based on studies

of human populations exposed to high

concentrations of particles and on

laboratory studies of animals and

humans, there are major human health

concerns associated with PM. These

include deleterious effects on breathing

and the respiratory system, aggravation

of existing respiratory and

cardiovascular disease, alterations in the

body’s defense mechanisms against

foreign materials, direct and indirect

damage to lung tissue resulting in

fibrosis, carcinogenesis, and premature

death. The major subgroups of the

population that appear to be most

sensitive to the effects of particulate

matter include individuals with

emphysema-like conditions or

cardiovascular diseases, chronic

obstructive pulmonary disease, those

with influenza, asthmatics, the elderly,

and children. PM–10 also soils and

damages materials, and fine particles are

a major cause of visibility impairment in

the United States.10

All particles in the atmosphere scatter

light and, hence, reduce visibility.

However, light is scattered most

efficiently by particles with a diameter

of 0.5–1.0 micrometers. Secondary

particles such as nitrates are in this size

range. As discussed in the RIA, in

locations such as the western U.S.,

where the ambient levels of SO2 tend to

be low, EPA believes nitrate particles

are major contributors to visibility

attenuation.

c. Other Secondary Effects of NOX

NOX is a major contributor to acid

deposition. The damage caused by acid

deposition continues to be documented

and includes acidification of surface

waters and soil, reduction in fish

populations, damage to forests and

associated wildlife, soil degradation,

damage to materials, monuments,

buildings, etc., and reduced visibility.11
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33425

11 ‘‘Acid Deposition Standard Feasibility Study, A

Report to Congress,’’ prepared for the U.S.

Environmental Protection Agency by the Cadmus

Group, Inc., under Contract Number 68–D2–0168,

February 1995.

12More information about EPA’s position on the

relationship between NOX and acid deposition may

be found as item II–A–13 in Docket A–95–28, titled

Draft Report: Adverse Effects of Nitrogen Oxides

and Benefits of Reductions.

13 Deposition of Air Pollutants Into the Great

Waters: First Report to Congress, EPA–453/r–93–

055, May 1994.

14See comments from STAPPA/ALAPCO in

Docket A–95–27.

Effects of acid deposition are most

pronounced during springtime

snowmelts, when ‘‘pulses’’ of highly

acidic water, often containing high

concentrations of toxic aluminum, enter

lakes and streams. In addition, nitrogen

compounds deposited on ecosystems

can transport acids already contained in

the soils and thus contribute to the

acidification of those ecosystems.

Although one commenter on the

ANPRM, API, challenged the

importance of NOX control in reducing

acid deposition, EPA believes that

geographically broad controls like those

proposed in this action represent a costeffective method of reducing overall

levels of deposited acid.12

Another secondary effect of NOX

emissions is their role in the overgrowth

of algae and other plants and oxygen

depletion (eutrophication) in coastal

estuaries in the eastern part of the

country, including the Chesapeake Bay,

as well as other estuaries and coastal

waters.13 Airborne nitrogen compounds

act as fertilizers for plant growth,

contributing an estimated 25 percent of

nitrogen loading in some coastal waters.

In waters where nitrogen compounds

are the limiting factor, eutrophication is

resulting in the reduction or loss of

commercially valuable aquatic/marine

species as well as diminution of waterrelated recreational activities. EPA

addressed this effect on estuaries in the

ANPRM and received no comments

counter to the Agency’s assessment;

comment on this issue is encouraged.

EPA encourages comment on all

aspects of its review of the human

health and environmental impacts of

ozone, NOX, and PM (especially

secondary nitrate PM), both in this

preamble and in the Regulatory Impact

Analysis.

B. Need for NOX and VOC Control To

Address Ozone and PM Issues

1. Regional NOX Control as a Strategy

for Addressing Regional Ozone

Problems

The precursors to ozone and ozone

itself are transported long distances

under some commonly occurring

meteorological conditions. Specifically,

concentrations of ozone and its

precursors in a region and the transport

of ozone and precursor pollutants into,

out of, and within a region are very

significant factors in the accumulation

of ozone in any given area. Regionalscale transport, as it is discussed in this

proposal, may occur within a state or

across one or more state boundaries.

Local source NOX and VOC controls are

key parts of the overall attainment

strategy for nonattainment areas.

However, the ability of an area to

achieve ozone attainment and thereby

reduce ozone-related health and

environmental effects is often heavily

influenced by the ozone and precursor

emission levels of upwind areas. Thus,

for many of these areas, EPA believes

that attainment of the ozone NAAQS

will require control programs much

broader than strictly locally focused

controls to take into account the effect

of emissions and ozone far beyond the

boundaries of any individual

nonattainment area.

EPA therefore believes that effective

ozone control requires an integrated

strategy that combines cost-effective

reductions in emissions from both

mobile and stationary sources. EPA’s

current initiatives, including the

national highway heavy-duty engine

standards proposed in this action, are

components of the Agency’s integrated

ozone reduction strategy.

By the time the 1990 amendments to

the Clean Air Act were passed, the

understanding that many areas face

regional-scale ozone problems was well

established. Before 1990, the Act

required states to address the

contribution of their pollution to other

areas’ attainment of the ozone standard.

Then, in the 1990 amendments,

Congress included additional provisions

for states to address regional ozone

transport in their efforts to reach

attainment by the statutory deadlines

(the Northeast Ozone Transport Region

and Commission resulted from these

provisions). Since 1990, the

understanding of regional transport of

ozone precursors and ozone itself has

continued to expand.

The problem of regional transport of

ozone and its precursors is widely

recognized by the states. In response to

concerns about this problem raised by

state environmental commissioners

comprising the Environmental Council

of the States (ECOS), EPA has worked

closely with states in the Ozone

Transport Assessment Group (OTAG) to

develop various recommended control

measures intended to address the

regional nature of ozone. Similarly, state

and local air administrators, under the

auspices of STAPPA and ALAPCO,

recently passed a unanimous resolution

endorsing national NOX emission

regulations.14

As the understanding of the

photochemical phenomena related to

ozone has developed, NOX control

options have received increasing

attention. Especially in addressing

regional-scale ozone problems, control

of NOX has emerged as the primary

strategy. VOC control, by comparison, is

seen as most effective in addressing

localized ozone peak concentrations

found in or near major urban areas. As

discussed further below, EPA has

conducted modeling studies in recent

years covering the eastern half of the

U.S., which have reinforced the

understanding that regional-scale

control of NOX emissions will be

essential to reducing the levels of

transported ozone in large areas of the

Northeast, Southeast, and Midwest. EPA

believes that ozone problems in

California also represent regional

problems that would be susceptible to

regional NOX control. Thus, the extent

of local controls that will be needed to

attain and maintain the ozone NAAQS

in and near seriously polluted cities is

sensitive both to the amount of ozone

and precursors transported into the

local area and to the specific

photochemistry of the area. In some

cases (e.g., portions of the Northeast

Corridor, the Lake Michigan area,

Atlanta, and California) preliminary

local modeling performed by the states

indicates that it will likely not be

feasible to find sufficient local control

measures for individual nonattainment

areas unless transport into the areas is

reduced in some manner. EPA has

carefully considered this important

relationship between local and regional

NOX controls for individual areas and

regions and for the country as a whole,

as summarized in the next sections. EPA

requests comment on these issues as

well as general comments on the need

for regional-scale NOX controls.

a. Action by States and EPA To Achieve

CAA Air Quality Goals

Title I of the 1990 Clean Air Act

amendments (Sections 181–185(b),

generally) established an aggressive

strategy for ozone nonattainment areas

to come into compliance with the ozone

NAAQS. (The case of attainment of the

PM NAAQS is discussed in section B.3.

below.) The Act’s strategy provides the

framework for action by states and EPA

for national, regional, and local controls.

Under these provisions, states are

expected to submit State

Implementation Plans (SIPs)
33426 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

15Memorandum from Mary D. Nichols, Assistant

Administrator for Air and Radiation, to EPA

Regional Administrators, re Ozone Attainment

Demonstrations, March 2, 1995.

16 ‘‘Section 182(f) Nitrogen Oxides (NOX)

Exemptions—Revised Process and Criteria,’’ EPA

Memo from John S. Seitz, Director, OAQPS, to

Regional Air Directors, February 8, 1995.

17 ‘‘Section 182(f) Nitrogen Oxides (NOX)

Exemptions—Revised Process and Criteria,’’ EPA

Memo from John S. Seitz, Director, OAQPS, to

Regional Air Directors, May 27, 1994.

demonstrating how each nonattainment

area will reach attainment of the ozone

NAAQS. Based on the degree that ozone

concentrations in an area exceed the

standard, the Act spells out specific

requirements that states must

incorporate into their attainment plans

and sets specific dates by which

nonattainment areas must reach

attainment.

For nonattainment areas designated as

serious, severe, or extreme, state

attainment demonstrations involve the

use of photochemical grid modeling

(e.g., Urban Airshed Modeling, or UAM)

for each nonattainment area. Although

these attainment demonstrations were

due November 15, 1994, the magnitude

of this modeling task, especially for

areas that are significantly affected by

transport of ozone and precursors

generated outside of the nonattainment

area, has delayed many states in

submitting complete modeling results.

Recognizing these challenges, EPA

recently issued guidance on ozone

demonstrations, based on a two-phase

approach for the submittal of ozone SIP

attainment demonstrations.15 Under

Phase I, the state is required to conduct

limited UAM modeling and submit a

plan implementing a set of specific local

control measures to achieve major

reductions in ozone precursors. Phase II

involves a two-year process during

which EPA, the states, regional

associations, and other interested

parties can improve emission

inventories and modeling and identify

regional measures that may be needed to

supplement the local controls of Phase

I. These improved analyses are then to

be considered by states in identifying

additional local control measures that

may be needed to attain the NAAQS by

the statutory dates. Currently, under

Phase I of the process, states are

submitting plans and EPA is taking

action to approve or disapprove them.

As part of these Phase I submittals,

some states have indicated that on the

basis of preliminary information, locally

based stationary source NOX controls in

those nonattainment areas would not be

helpful—or, in a few cases, would be

detrimental—to attainment of the ozone

NAAQS. These states have petitioned

EPA under Section 182(f) of the Act for

exemptions from local NOX stationary

source controls they would otherwise be

required to implement under

Reasonably Available Control

Technology (RACT) and New Source

Review (NSR) regulations. In general,

Section 182(f) provides that waivers

must be granted if states show that

reducing NOX within a nonattainment

area would not contribute to attainment

of the ozone NAAQS within the same

nonattainment area.16 This section of

the Act was added in 1990 in

recognition of the fact that NOX

reductions within some nonattainment

areas can increase ozone concentrations.

Section 182(f) of the Act also requires

EPA to limit the assessment of state

petitions to the effect that NOX

reductions within a nonattainment area

are likely to have on that local area’s

ability to meet the NAAQS (i.e., this

section of the Act does not permit an

assessment of pollutant transport into

and out of the area). However, in their

modeling supporting their overall

attainment demonstrations under Phase

II, states will need to project the levels

of ozone and precursors that are

transported into the area (these

assumptions are called ‘‘boundary

conditions’’). In many areas, the

boundary conditions used in Phase II

modeling will need to assume that

significant reductions in ozone and NOX

will be accomplished upwind. Thus, in

Phase II of the current process, it will be

necessary for states and EPA to consider

the impacts of NOX controls at both the

local and regional levels in assessing

how attainment can be achieved. As

described below, in most cases, EPA

believes that broad, regional ozone and

NOX control in upwind areas will be

necessary for Phase II demonstrations

even where Phase I modeling results

currently indicate that local NOX

controls may be unnecessary or

detrimental.

b. Local NOX Exemptions’ Relation to

Regional NOX Control Needs

The state petitions for exemption from

local RACT and NSR requirements so

far granted by EPA fall into three

categories: (1) EPA approved four state

petitions for areas (Dallas and El Paso,

TX, Birmingham, AL, and northern

Maine) for which Phase I modeling

shows that the areas will attain the

ozone NAAQS without additional NOX

controls (there is no analysis for these

areas showing NOX controls are either

beneficial or detrimental); (2) EPA

granted exemptions for five areas (Baton

Rouge, LA, Beaumont, TX, Houston, TX,

the Lake Michigan area, and Phoenix,

AZ) after Phase I modeling showed that

local NOX controls could worsen peak

ozone concentrations in the

nonattainment areas; (3) EPA approved

ten other petitions based on monitoring

data that shows the areas attained the

ozone NAAQS without additional NOX

controls (there is no analysis for these

areas showing NOX controls are either

beneficial or detrimental). It is

important to note that only five

exemptions that have been granted

assert that NOX controls would be

detrimental to attainment plans.

It is very important to view EPA’s

granting of exemptions from local NOX

controls in some areas under Phase I of

the attainment process in the broader

context of the ultimate Phase II

determinations. Although EPA believes

that it is reasonable to initiate new

control programs to address regional

ozone problems on the strength of

information already available (see

Section II.E. below), a better overall

picture of regional and local air quality

phenomena for each area will exist once

Phase II demonstrations are completed.

Some commenters on the ANPRM have

argued that EPA’s granting of local NOX

exemptions for some areas during Phase

I of the process should be interpreted as

a conclusion by the Agency that no

further NOX controls—local, regional, or

national—will be necessary for these

areas to reach and maintain attainment

or that such controls would be harmful.

API commented that EPA ‘‘has failed to

reconcile [the] two incongruous

policies,’’ referring to the initiation of

new regionally based controls in a

period when local NOX exemptions are

being granted in some areas. Similarly,

the National Petroleum Refiners

Association (NPRA) stated that they

view such simultaneous action to be

‘‘contradictory and arbitrary.’’ For

several reasons, EPA believes that such

characterizations fail to recognize the

limited role of local NOX exemptions

within the broader Phase II attainment

demonstration process.

First, because most of the NOX waiver

petitions contain no modeling analyses

and many of those that contain

modeling analyses are being

supplemented with improved Phase II

modeling, EPA’s approval of each NOX

exemption has been granted on a

contingent basis.17 That is, a

monitoring-based exemption lasts for

only as long as the area’s monitoring

data continue to demonstrate

attainment. Thus, if a violation is

monitored (prior to the area being

redesignated as being in attainment) the

exemption would be revoked and the
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33427

18NOX Supplement to the General Preamble, 57

FR 55628 (Nov. 25, 1992).

19See Regional Ozone Modeling for Northeast

Transport (ROMNET), EPA Doc. EPA–450/4–91–

002a (June 1991), and Chu, S.H., E.L. Meyer, W.M.

Cox, R.D. Scheffe, ‘‘The Response of Regional

Ozone to VOC and NOX Emissions Reductions: An

Analysis for the Eastern United States Based on

Regional Oxidant Modeling,’’ Proceedings of U.S.

EPA/AWMA International Specialty Conference on

Tropospheric Ozone: Nonattainment and Design

Value Issues, AWMA TR–23, 1993.

requirement to adopt NOX controls

would again apply. Similarly, any

modeling-based exemption may need to

be withdrawn if updated modeling

analyses for Phase II reach a different

conclusion than the Phase I modeling

on which the exemption was based.18

Second, as discussed above, Section

182(f) of the Act does not permit EPA

to consider regional-scale NOX issues

when acting on state petitions for

exemptions from local NOX controls.

Because NOX has been shown to be

effective in reducing regionally

transported ozone, the broader modeling

under Phase II is expected to show that

many areas will need regional NOX

controls to counter expected growth and

maintain or reach attainment. Where

this occurs, it might also lead to

withdrawal of exemptions from local

NOX controls.

Third, EPA has separate authority

under the CAA (Section 110(a)(2)(D)) to

require a state to reduce emissions from

sources where there is evidence

showing that transport of such

emissions would contribute

significantly to nonattainment or

interfere with maintenance of

attainment in other states. For example,

local NOX controls may need to be

reinstated if Phase II modeling shows

that additional reductions in that area

are needed for attainment and

maintenance in downwind areas,

superseding any NOX exemption that

may have been granted under Phase I.

If this need arises, Section 110(a)(2)(D)

would provide EPA the authority to

require such additional reductions.

EPA therefore believes that decisions

about initiating new NOX control

programs that have a regional-scale

effect are appropriately made based on

the best understanding available at that

time of the broad attainment needs of all

areas. As is discussed below for several

regions of the country, there is strong

evidence that regional-scale controls

will be needed to achieve and maintain

attainment. As a part of the Phase II

assessments, the impact of and need for

NOX control and the continuation or

withdrawal of local NOX exemptions

would be taken fully into account. Thus,

in assessing EPA’s overall NOX policy,

it is important to understand the limited

and perhaps temporary nature of

exemptions from NOX controls in some

areas within the context of the

anticipated implementation of broader,

regional NOX control strategies upon

completion of the Phase II modeling.

An important issue that states and

EPA will consider during the Phase II

process is the interaction between

prospective regional control programs

and local air quality conditions. For

nonattainment areas that are granted

local NOX exemptions based on the lack

of need for additional NOX controls (this

covers the great majority of current and

pending exemptions, as shown above),

introducing regional controls that have

an effect both inside and outside the

nonattainment area is generally not

expected to harm air quality within the

area. In the few areas where Phase I

modeling indicates that reduction of

NOX in the area could increase ozone in

some locations, a balancing of all

relevant factors will be necessary if

Phase II modeling reinforces that a

significant potential problem exists. For

example, if ozone and NOX transported

into the area would be significantly

reduced by regional-scale controls, the

absolute level of ozone within the area

would drop, changing the

photochemistry of the area and

potentially offsetting any localized

detriment to air quality that might still

be introduced by the regional controls

(e.g., cleaner trucks within the area).

In its comments on the ANPRM, API

referred to recent modeling studies

performed by the Modeling Ozone

Cooperative, which API says challenge

EPA’s earlier conclusions about the

need for NOX control in the Northeast.

EPA is aware of and is reviewing the

results of these modeling studies. Based

on EPA’s evaluation of these studies to

date, the Agency finds that these studies

in fact support EPA’s previous

conclusions that broad regional-scale

controls will be necessary for the

Northeast and other areas to attain and

maintain the ozone NAAQS. As API

observes, these studies also predict that

NOX reductions may increase ozone

levels in several areas. API also cites

modeling performed by the Lake

Michigan Air Directors Consortium

(LADCO), which appears to predict

similar results for the Lake Michigan

area. As described below, the LADCO

studies do however, suggest that

reductions in regional ozone at the

boundary of their modeling domain will

likely play a key role in determining

whether the NAAQS can be attained

with local VOC-oriented control

measures.

EPA is concerned about these results

and is interested in additional modeling

to further explore the degree to which

NOX control programs may increase

ozone in some areas. Questions not

answered by current modeling include

(1) how the results change if additional

stationary and mobile source NOX and

VOC control programs are assumed to

be implemented by the time the heavyduty engine emission standards

proposed in this action would be in

place and (2) whether urban-scale

modeling of higher resolution can shed

more light on how widespread potential

areas of increased ozone might be.

EPA expects that on balance it will

continue to be preferable to achieve

regional-scale NOX and ozone

reductions whenever possible, even

where current modeling indicates that

increases in ozone may occur in parts of

some areas. EPA requests comments on

this general assessment, as well as on

the discussions of individual regions

below; comments including additional

data and modeling results that challenge

or reinforce EPA’s views will be

particularly valuable.

2. Role of Regional-Scale NOX Control

in Addressing Ozone Problems in

Several Regions of the U.S.

EPA believes that the best data and

modeling available show that NOX in

several large geographic areas of the

country will continue to contribute

greatly to ozone problems in

nonattainment areas well into the

future. Together, these areas account for

about 87 percent of nationwide NOX

emissions from heavy-duty vehicles (see

Chapter 7 of the RIA). Several of these

regions are discussed individually

below. Where there are existing or

pending exemptions from local NOX

controls in the region, their relationship

to regional-scale NOX controls is also

discussed.

a. Eastern United States

There is a growing body of evidence

that reducing regional ozone levels

holds the key to the ability of a number

of the most seriously polluted

nonattainment areas in the Eastern

United States, in both the Southeast and

the Northeast, to attain and maintain the

ozone NAAQS. Regional Oxidant

Modeling (ROM) studies conducted by

EPA (called the ROMNET and Matrix

studies) reinforce that reducing NOX

emissions in large geographical regions

is the most effective approach for

reducing ozone levels in those large

regions.19 At the same time, these

studies, as well as ongoing UAM

modeling by states, suggest that

reductions in VOC emissions may be
33428 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

20Because of the significant role that NOX plays

in atmospheric chemistry, additional regional NOX

control can also be very helpful in addressing the

problems of year-round NOX deposition in the

Chesapeake Bay and other nitrogen-limited lakes

and estuaries and acid deposition and visibility

degradation in the eastern U.S. (as well as parts of

the West).

21The Northeast Ozone Transport Region (OTR)

is comprised of the states of Maine, New

Hampshire, Vermont, Massachusetts, Rhode Island,

Connecticut, New York, New Jersey, Pennsylvania,

Delaware, Maryland, and the Consolidated

Metropolitan Statistical Area that includes the

District of Columbia and northern Virginia.

22Environmental Protection Agency, Low

Emission Vehicle Program for Northeast Ozone

Transport Region; Final Rule, 60 FR 48673, January

24, 1995.

23Environmental Protection Agency, ‘‘Summary

of EPA Regional Oxidant Model Analyses of

Various Regional Ozone Control Strategies,’’

November 28, 1994; Kuruville, John et al.,

‘‘Modeling Analyses of Ozone Problem in the

Northeast,’’ prepared for EPA, EPA Document No.

EPA–230–R–94–108, 1994; Cox, William M. and

Chu, Shao-Hung, ‘‘Meteorologically Adjusted

Ozone Trends in Urban Areas: A Probabilistic

Approach,’’ Atmospheric Environment, Vol. 27B,

No. 4, pp 425–434, 1993.

24 ‘‘The State of the Southern Oxidant Study

(SOS): Policy-Relevant Findings in Ozone Pollution

Research,’’ 1988–1994. North Carolina State

University, April 1995. See this reference for all

statements in this paragraph.

25Lake Michigan Ozone Study; Lake Michigan

Ozone Control Program: Project Report, December

1995.

key to reducing locally generated peak

ozone concentrations.20

In its analysis supporting the approval

of a Low Emission Vehicle program in

the mid-Atlantic and Northeast states

comprising the Ozone Transport Region

(OTR), EPA reviewed existing work and

performed new analyses to evaluate in

detail the degree to which NOX controls

are needed.21 22 These studies showed

that NOX emissions must be reduced by

50 to 75 percent from 1990 levels

throughout the OTR. These studies

showed that VOC emissions must also

be reduced by 50 to 75 percent in and

near the Northeast urban corridor. The

studies also concluded that transport of

ozone and precursors from upwind

areas both inside and outside the OTR

contributes significantly to ozone

predictions in much of the OTR.

More recently, three studies have

become available confirming the

conclusions of the earlier studies. In one

of these, the Agency performed new

ROM analyses evaluating the eastern

third of the U.S. and southern Canada.23

Taken together, these studies strongly

support the view that NOX emissions

must be reduced in the range of 50 to

75 percent throughout the OTR and that

VOC emissions must be reduced by the

same amount in and near the Northeast

urban corridor to reach and maintain

attainment.

Among the Northeast states, only

Maine, based on unique air trajectory

patterns, has sought an exemption from

local NOX control; this exemption is

granted for the northern part of the state.

b. The Southeast

A recent Southern Oxidant Study

report describes the results of research

showing that, in the South, relatively

high concentrations of ozone are

measured in both rural and urban

areas.24 These pervasive levels of ozone,

while for the most part not in excess of

the current ozone NAAQS, form a

background into which individual

urban plumes are interspersed.

Preliminary modeling analyses

performed by the State of Georgia

Department of Natural Resources

suggests that it will be very difficult to

meet the NAAQS in Atlanta during

episodes similar to those modeled

episodes, given the high background

levels of ozone that appear to prevail in

the South. Further analyses of

monitored data by Southern Oxidant

Study investigators suggest that the

background ozone levels are likely to be

more responsive to reductions in NOX

emissions than in VOC emissions. There

are no petitions at this time for local

NOX exemptions in this region.

c. The Lake Michigan Area

Modeling studies performed to date

for the states surrounding Lake

Michigan (Wisconsin, Illinois, Indiana,

and Michigan) under Phase I of their

attainment demonstrations clearly

indicate that reducing ozone and

precursors transported into the

nonattainment areas would have a

significant effect on the number and

stringency of local control measures

needed to meet the ozone NAAQS.25

These studies suggest that without such

region-wide reductions, the necessary

degree of local control will be very

difficult to achieve, even with very

stringent local controls. The EPA Matrix

study referenced above reinforces that

regional NOX control will be effective in

reducing ozone across the Midwest

region. Taken together, the information

available to date suggests that additional

reductions in regional NOX emissions

will probably be necessary in meeting

the NAAQS in the Chicago/Gary/

Milwaukee area and downwind

(including western Michigan), even

though currently available modeling

shows that there may be a detrimental

effect from applying NOX controls

locally in and near the major

nonattainment areas, in the absence of

regional controls.

EPA has granted an exemption from

local NOX controls for several areas in

the Lake Michigan region based on

Phase I modeling. Phase II modeling is

underway by these states, which the

Agency is hopeful will clarify the

conditions under which NOX controls

might cause an increase in ozone in the

future, the magnitude of such an

increase, and the parts of the

nonattainment areas in this region in

which this may occur.

d. Eastern Texas

There has been only limited modeling

work focusing on the air quality

characteristics of the eastern Texas

region to date. The State of Texas has

requested and been granted exemptions

for the Houston and Beaumont/Port

Arthur nonattainment areas, based on

Phase I modeling that predicted that

additional local NOX controls could

worsen the ozone problem. New

modeling is underway by the state, but

there is not yet enough data to draw

conclusions about the potential effect of

transport of ozone and its precursors on

these areas. This uncertainty has led the

state to request that the exemptions

from local NOX controls in these areas

be granted on a temporary basis while

more sophisticated modeling is

conducted.

e. California

The State of California has submitted

their ozone SIP to EPA for approval,

relying on both NOX and VOC

reductions for most California

nonattainment areas, comprising most

of the populated portion of the state, to

demonstrate compliance with the

NAAQS. Specifically, the revised SIP

projects that the following NOX

reductions are as follows: South Coast,

59 percent; Sacramento, 40 percent;

Ventura, 51 percent; San Diego, 26

percent; and San Joaquin Valley, 49

percent. For VOC, the required

reductions will be the following: South

Coast, 79 percent; Sacramento, 38

percent; Ventura, 48 percent; San Diego,

26 percent; and San Joaquin Valley, 40

percent.

EPA has granted exemptions from

local NOX controls within three

California nonattainment areas; EPA

believes that these actions do not affect

the broader need for regional NOX

controls in large parts of the state for

ozone and PM NAAQS attainment and

maintenance.

3. Secondary PM Formation as a

Regional Issue

Measurements of ambient PM in some

western U.S. urban areas that are having

difficulty meeting the current NAAQS

for PM–10 have indicated that

secondary PM is a very important

component of the problem. Nitrates
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33429

26Summary of Local-Scale Source

Characterization Studies, EPA–230–F–95–002, July,

1994.

27A discussion of the data used for projecting

emissions from various sources is found in the

Regulatory Impact Analysis.

28The data in these and the succeeding figures in

this proposal are discussed in the RIA, and take into

account the expected effects of various CAA control

programs that have been promulgated at the time

of the modeling. These include Tier I tailpipe

standards, new evaporative emission test

procedures, enhanced inspection and maintenance

requirements, reformulated gasoline, oxygenated

fuels, and California LEV (Low Emission Vehicle)

requirements. Nonroad NOX emission projections

also reflect the future effects of existing nonroad

emission regulations. The potential effects of

contemplated National LEV requirements or other

programs are not reflected in the data. In these

figures, nonroad emission data includes emissions

from a broad range of nonroad sources including

locomotives, aircraft, and marine vessels.

(e.g., ammonium nitrate) are a primary

constituent of this secondary PM. For

example, on days when PM–10 is high

in Denver, about 25 percent of the

measured particulate is ammonium

nitrate. In the Provo/Salt Lake City area,

secondary PM accounts for

approximately 50 percent of the

measured PM, with nitrates being an

important component of the secondary

particulate. Secondary nitrate PM levels

as high as 40 percent of the 24-hour

PM–10 NAAQS standard have been

measured in the Los Angeles Basin and

concentrations of nitrate PM about one

third of the NAAQS have been

measured in the San Joaquin Valley.26

NOX is a critical reactant in the

complex chemical reactions which

eventually result in the formation of

atmospheric nitrates. Thus, control of

NOX emissions from heavy-duty

vehicles will have a positive effect in

reducing atmospheric ammonium

nitrate. Because the atmospheric

chemistry of secondary PM formation

has common attributes to that of ozone,

secondary PM also tends to be a

regional, rather than a strictly local

phenomenon. For this reason, EPA

believes that, as is the case for ozone,

regional NOX controls can be very

effective in reducing secondary PM over

a significant area. For example,

California’s revised SIP concludes that

secondary formation of nitrate

particulate (primarily ammonium

nitrate) contributes to the particulate

problem in the South Coast Air Basin

and the San Joaquin Valley. The Agency

requests comment on the role of

secondary particulate in PM–10

nonattainment in specific areas and the

effect of regional NOX controls on such

emission; comments that include

additional data will be particularly

valuable.

The sources that contribute to PM

levels can vary significantly from area to

area. In many areas in the western U.S.,

re-entrained fugitive dust emissions

dominate the overall PM emissions

inventory. In large urban areas,

however, direct PM emissions from

heavy-duty diesel vehicles, as well as

the secondary PM from NOX produced

by all heavy-duty vehicles, are believed

to contribute significantly to elevated

PM levels.

As can be seen from the discussion

above, NOX emissions have a number of

different fates in the atmosphere. In

some situations, such as the formation

of atmospheric ozone, NOX is used as a

catalyst but not consumed. A single

NOX molecule can potentially be

involved in many photochemical

reactions producing several ozone

molecules. In other cases, such as the

formation of nitrate particulate and acid

precipitation, NOX is consumed. All

NOX eventually leaves the atmosphere

in dry gas, particulate deposition, or in

wet deposition. NOX has a mean

residence time in the atmosphere on the

order of several days.

It is clear that heavy-duty vehicle

NOX emissions have a role in the

formation of ozone, nitrate particulates,

and acid precipitation. The relative

partitioning varies across the country

depending on factors such as geography,

meteorology, and the concentration of

other atmospheric pollutants. This

preamble and the RIA contain

information and analyses describing the

positive impact of this proposal on

ozone, PM, and other environmental

effects, which EPA believes form a

strong basis for this proposal. EPA is

conducting additional studies to further

refine our understanding of the role of

NOX in the formation of ozone and

nitrate PM. EPA requests comment and

data regarding the relative partitioning

of NOX emissions.

C. National Emission Trends Related to

Ozone and PM

1. National NOX and VOC Emissions

Trends

Figure 1 displays projected total NOX

emissions over the time period 1990 to

2020, including a breakdown between

stationary and mobile source

components over the same period.27

Figure 2 presents similar data for VOC

emissions for the period 1990 to 2010

(later-year projections for VOC are

under development).28 As the figures

show, a similar pattern is projected for

both of these ozone precursor emissions.

Initially, the projections indicate that

national inventories will decrease over

the next few years as a result of

continued implementation of finalized

CAA stationary and mobile source NOX

control programs. After the year 2000,

however, when implementation of these

CAA programs is largely completed and

the pressure of growth continues, these

downward trends are expected to

reverse, resulting in rising national VOC

and NOX emissions.

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In its comments on the ANPRM, API

observed that monitoring data from

some areas show progress in reducing

ozone. EPA agrees that this progress

appears to be occurring and the Agency

believes that this progress may continue

for the next few years in many areas as

current NOX and VOC programs are

implemented. As shown in Figures 1

and 2 above, however, EPA believes

that, in the absence of significant new

control efforts, the current downward

trends in ozone precursor emissions

will be reversed in the middle of the

next decade. The Agency also believes

that the projected increase in emissions

will again increase ozone levels in

urban areas. EPA continues to examine

this issue and welcomes new modeling

analyses that relate NOX and VOC

emission trends to ozone levels.

2. PM Air Quality Issues and Emission

Trends

The overwhelming proportion of PM–

10 emissions is created by wind erosion,

accidental fires, fugitive dust emissions

(from road surfaces, agricultural tilling,

construction sites, etc.), and other

miscellaneous sources. As much as 85

percent of PM–10 in nonattainment

areas can be composed of these

‘‘crustal’’ and miscellaneous materials.

Since these sources are not readily

amenable to regulatory standards and

controls, it is appropriate to focus on the

‘‘controllable’’ portion of the particulate

pollution problem when considering the

need for PM controls. The result is

shown in Figure 3, which displays

national trends in PM–10 levels from

stationary and mobile sources,

including secondary nitrate PM,

projected for the twenty-year period

1990 to 2010. Similar to the pattern

discussed above for VOC and NOX

emissions, the figure shows that total

PM from these sources will decline

slightly as the beneficial effects of the

1990 CAA Amendments continue to be

felt. However, in the absence of

additional controls, including NOX

controls, mobile source and industrial

source PM emissions are expected to

rise after 2000.

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Currently, there are 82 PM–10

nonattainment areas across the U.S. As

discussed in section II.B.3. above, in

some areas of the West, nitrate

particulate represents between 15 and

40 percent of total particulate matter.

The level of nitrate PM is a function of

the availability of NOX. It is appropriate

to expect that the relative proportions of

nitrate particulate caused by stationary

and mobile sources are similar to the

relative contributions of NOX by these

source categories. Thus, based on the

NOX projections of Figure 1, which EPA

believes are generally typical of NOX

projections in the West, EPA estimates

that about half of total nitrate PM is

caused by mobile sources, or about one

tenth of total PM–10 in the western part

of the country. In the eastern part of the

country, peak fine particulate matter

levels occur in the summer, primarily

because photochemical processes

involving SO2 and NOX driven by strong

sunshine accelerate the formation of

sulfate and nitrate particulate matter.

Thus, reducing NOX over a broad area

is one strategy for reducing the net fine

particle formation in the East. EPA

requests comment, including applicable

data whenever possible, on its

assessment of the relationship of NOX to

ambient nitrate PM.

D. Contribution of Heavy-Duty Vehicles

to Mobile Source Emissions

Heavy-duty vehicles represent about

12 percent of nationwide NOX

emissions and are also an important

source of VOC (as a result of HC

emissions) and PM throughout the

country. This section reviews EPA’s

current estimates of the contribution of

heavy-duty vehicles to the nation’s

ozone, PM, and NOX air pollution

problems now and into the future. The

projections presented here incorporate

the emission reductions from all

national mobile source emission control

programs for which final regulations

were in place at the time of the

modeling and are discussed further in

the RIA.

1. National Mobile Source NOX

Emissions Trends

Figure 4 shows the total mobile

source NOX inventory by emission

source (light-duty vehicles, heavy-duty

vehicles, and nonroad engines)

projected over the next 25 years. For

light- and heavy-duty vehicles, the

figure shows a decline in emissions over

the next decade as current programs

phase in. The figure also shows,

however, that this current downward

trend is projected to end, resulting in a

return to current NOX levels in the

absence of further controls. Nonroad

emissions are projected to rise

throughout the period.

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2. National Mobile Source VOC Emissions Trends

Figure 5 shows the total national mobile source VOC inventory by emission source. As with the NOX emission

projections in Figure 4, this figure shows that light-duty vehicle emissions can be expected to decline for some years,

but then begin rising in the 2005 time frame. VOC emissions from heavy-duty vehicles and nonroad engines are projected

to rise gradually throughout this period.
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3. National Mobile Source PM Emissions Trends

EPA’s latest projected trends for directly emitted mobile source emissions of PM–10 are shown in Figure 6. The

figure shows that over the next 15 years the contribution of heavy-duty vehicles and other highway sources to PM–

10 pollution are expected to decrease significantly and then remain relatively constant well into the next decade.
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33439
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The emission data on which Figure 6

is based do not include secondary

nitrate PM–10 produced by the

transformation of NOX in the

atmosphere. EPA believes that for those

areas where secondary PM formed from

NOX is a problem, the proportions of

total secondary PM that may be

attributed to different emission source

categories mirror the proportions of total

NOX emissions from those sources in

those areas. Thus, based on the trends

for NOX emissions shown in Figures 1

and 4 above and assuming that the

availability of ammonia in the

atmosphere remains roughly constant,

the contribution of heavy-duty vehicles

to secondary PM problems can be

expected to decline slightly in the next

few years and then to begin to increase

again, likely reaching and exceeding

current levels after about 2020. Also

based on Figures 1 and 4, EPA believes

that on average the proportion of total

nitrate PM that may be attributed to

heavy-duty vehicles is in the same range

as the proportion of total NOX

contributed by these vehicles, or

roughly 10 percent.

As discussed earlier in this proposal,

EPA has not completed its assessment of

the relative importance of fine PM to

health and welfare concerns as

compared with PM–10. As a result, EPA

has not yet developed specific

projections showing the contribution of

heavy-duty vehicles to total fine

particulate emissions. However, since

nearly all mobile source related PM,

both directly emitted PM and secondary

nitrate PM formed from NOX emissions,

falls in the fine particulate category, it

follows that the relative contribution of

heavy-duty vehicles to total fine

particulate is greater than their

contribution to total PM–10.

E. Conclusions

1. The Rationale for Controlling HeavyDuty Vehicle Emissions

EPA believes that immediate proposal

of new emission standards for highway

heavy-duty engines is appropriate. The

decision to issue this NPRM is based on

thorough consideration of a range of

relevant factors, as described above.

Section II.A. presented the serious

effects to human health and the

environment of elevated levels of ozone

and other chemical products of NOX

emissions, including secondary PM .

That section describes a range of serious

respiratory health effects that have been

closely connected to exposure to ozone

levels exceeding the NAAQS, which

exist in many areas of the country. In

light of the many years of research by

many parties into the health effects of

ozone, the Agency believes that a clear

picture has emerged that, not only those

with existing respiratory conditions, but

also healthy adults and children are in

danger of experiencing medical

problems and a reduced quality of life

when exposed to elevated levels of

ozone. Also discussed were the variety

of health concerns that have been

associated with exposure to PM at levels

above the current NAAQS. Beyond

these and other serious health concerns,

Section II.A. also discussed major

impacts on vegetation, crops, coastal

estuaries, visibility, and other effects

that result from the transformation of

NOX into ozone, acid deposition, and

nitrate PM formed from NOX. The

current NAAQS levels reflect the need

to address exposure to ozone and PM

wherever the NAAQS standards are

exceeded.

Section II.B. discussed EPA’s belief

that the widespread exposure of people

to elevated ozone levels will continue

and worsen in the absence of major

regional-scale reductions in NOX. This

section discussed the regional

characteristic of the ozone problem and

how various large areas of the country

are projected to require regional-scale

NOX controls to reach and maintain

attainment of the ozone standard. EPA

believes this remains true even where

local NOX control waivers must be

granted under the CAA. This section

also noted that regional-scale control of

NOX would be beneficial in reducing

the formation of secondary PM in some

areas of the western U.S. and would

thereby assist these areas in reaching

and attaining the PM NAAQS.

Section II.B. also presented

projections of emissions over the next

20 to 30 years to help assess the

likelihood of continued air quality

problems in the future. In general, EPA’s

most recently developed emission

inventories show that national levels of

ozone precursors will tend to drop

slightly, but only temporarily, after

which they will return to current levels.

The link of these projected future

emissions to the formation of ozone was

reinforced by recent air quality

modeling projecting continued ozone

problems in major areas of the country

in the absence of new controls. The

information assembled in this section

leads EPA to believe that a strong need

exists for new regional-scale NOX

control programs over large areas of the

country if the negative trends are to be

arrested and reversed. Similarly, the

data on PM suggests that secondary PM

reductions will be helpful in reversing

a national trend of increasing PM

emissions, especially in the western

states.

Section II.C. presented national

mobile source emission inventories over

the next 20 to 30 years, divided into the

key mobile source categories. These

presentations showed that heavy-duty

vehicles contribute significantly to

mobile source NOX , VOC, and PM

emissions and to the overall trends in

mobile source emissions into the future.

In its comments on the ANPRM, API

gave several reasons why projections of

future emission inventories may be in

error and questioned the future

contribution of heavy-duty vehicle

emissions. Although EPA believes that

the projections presented in this

proposal can be improved and will

continue to take actions to improve

them, the Agency believes that they

represent the highest quality estimates

available today. As such, they clearly

indicate that heavy-duty vehicles will

remain significant contributors to these

emissions well into the future.

After consideration of all the available

information, including comments

received on the ANPRM, EPA believes

that heavy-duty vehicles contribute

significantly to air pollution, which has

a serious impact on health and the

environment. The Agency believes that

this body of information on balance

supports taking action to revise heavyduty engine emission standards, which

will reduce NOX, HC, and secondary PM

from this segment of mobile sources.

2. Appropriateness of a National HeavyDuty Vehicle Program

EPA further believes that the mobile

source emission control program

proposed in this action is most

appropriately national in scope, for

several reasons. First, as summarized

above, the regional character of both

ozone and secondary PM formation

leads EPA to believe that major new

NOX controls over large regions of the

country are needed to achieve the

regional-scale ozone and PM reduction

many areas require. Control of NOX

from heavy-duty vehicles and other

mobile sources are effective approaches

to such regional control since the

resulting control covers a wide area.

Second, heavy-duty vehicles, like other

mobile sources, represent an emissions

source that itself crosses boundaries of

nonattainment areas, states, and regions.

A mobile source control program that

covers only certain parts of the country

has the disadvantage of allowing highemitting vehicles to travel regularly into

areas with more stringent requirements,

compromising the effectiveness of the

program. Finally, the structure and

marketing patterns of the engine and

vehicle manufacturing industries would

make it impractical and inefficient for a
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29 40 CFR Part 86.090–2.

30 40 CFR Part 86.093–2.

patchwork of different emission

standards to be enacted in various parts

of the country. Rather, for engine

manufacturers to achieve economies of

scale and to concentrate research and

development resources most effectively,

EPA believes it is most practical to

establish a single set of emission

requirements applying to engines in

trucks and buses used anywhere in the

country. A key reason why EPA, CARB,

and engine manufacturers agreed to a

Statement of Principles was the

potential for nationally harmonized

requirements for heavy-duty vehicles.

3. Issues of Timing

EPA also believes that for the

anticipated benefits of new highway

heavy-duty engine emission standards

to be available when they are needed, it

is best to finalize such a program in the

near future. There are several reasons

for and positive consequences of

expeditious promulgation of new

emission requirements for heavy-duty

engines. The primary reason to begin

the process now is that the current

emission and air quality projections

discussed above project a need in many

areas of the country for significant

additional emission reductions in the

post-2000 period to reach and maintain

attainment.

In addition, the highway heavy-duty

engine manufacturers have

communicated to EPA that to meet the

stringent standards proposed in this

action for model year 2004 and later,

they need to have the precise emission

requirements affecting them in place

and begin work toward those goals very

soon. The industry’s perspective is

based on its expectation that the

standards proposed here would

represent a very significant

technological challenge requiring large

investments by the members of the

industry. EPA’s technology assessment

is consistent with the industry view. If

new standards are established by

approximately the end of 1996, about

two years will be available before the

proposed 1999 technology review for

manufacturers to marshall appropriate

resources to achieve significant

technological progress. Then, if such

progress is confirmed at that time, about

four years will remain for additional

resources to be assembled and the new

technologies to be developed and

incorporated into 2004 model year

engines. Based on the Agency’s

technology assessment as of the time of

this proposal, EPA agrees that it is best

to set the process in motion now to

achieve the full benefits of cleaner

heavy-duty vehicles beginning in 2004.

Another compelling reason to initiate

the process of enacting new heavy-duty

engine emission requirements soon is

that the Agency is proposing to

encourage voluntary marketing of

cleaner engines, especially engines that

incorporate new technologies, earlier

than 2004 (see Section III.B. below for

proposed changes to the Averaging,

Banking, and Trading program). An

expeditious completion of the

rulemaking process would encourage

manufacturers to consider such options

in the earliest possible model year.

State air quality planners will also

benefit if the program proposed in this

action can be formally established soon.

States must soon finalize ozone SIPs

demonstrating attainment in the years

ahead, and expeditious EPA action on

additional heavy-duty vehicle emission

reductions will allow states to know

whether to incorporate expected

reductions from heavy-duty vehicle

controls into their SIPs. At the same

time, any significant delay in

promulgation might also require a delay

in the year of implementation past 2004,

postponing the full benefit of the

program as an air quality strategy. For

this and the other reasons given in this

section, EPA plans to finalize the

proposed requirements as soon as

possible should the Agency reach a final

determination that such a program is

warranted.

III. Proposed Program for Reducing

Highway HDE Emissions

A. Background on Highway HDE

Standards

Under EPA’s classification system,

vehicles with a gross vehicle weight

rating (GVWR) over 8,500 pounds are

considered heavy-duty vehicles. (The

State of California classifies the lighter

end of EPA’s heavy-duty class as

‘‘medium-duty vehicles.’’) Heavy-duty

engines (HDEs) are used in a wide range

of heavy-duty vehicle categories, from

small utility vans to large trucks.

Because one type of HDE may be used

in many different applications, EPA

emission standards for heavy-duty

vehicles are based on the emissions

performance of the engine (and any

associated aftertreatment devices)

separate from the vehicle chassis.

Testing of an HDE consists of exercising

it over a prescribed duty cycle of engine

speeds and loads using an engine

dynamometer.

Highway HDEs are categorized into

diesel and otto-cycle (predominantly

gasoline-fueled) engines with each, in

some cases, having different standards

and program requirements. EPA has

further subdivided heavy-duty diesel

engines (HDDEs) into three

subclassifications or ‘‘primary intended

service classes’’; light, medium, and

heavy HDDEs. HDDEs are categorized

into one of the three subclasses

depending on the GVWR of the vehicles

for which they are intended, the usage

of the vehicles, the engine horsepower

rating, and other factors 29. The

subclassifications allow EPA to more

effectively set requirements that are

appropriate for the wide range of sizes

and uses of HDDEs. With one exception,

emission standards are the same for

HDDE in all of the subclasses but other

programmatic requirements differ as

appropriate. Engines used in ‘‘urban

buses’’ (large transit buses)30, which fall

mostly in the heavy HDDE subclass,

have somewhat different standards and

program requirements. The standards

and program requirements for the

various categories and types of engines

are discussed below and in following

sections, as appropriate.

Emissions from HDEs are measured in

grams of pollutant per brake

horsepower-hour (g/bhp-hr) or, in more

recent regulations, in grams per kilowatt

hour (g/kw-hr). These units for emission

rates recognize that the primary purpose

of HDEs is to perform work and that

there is a large variation in work output

among the engines used in heavy-duty

applications. This system allows EPA to

apply the same standards to a very wide

range of engines.

Emission standards have been in

place for highway diesel and gasolinefueled HDEs since the early 1970s. The

first regulations focused on control of

emissions of smoke. Subsequent

regulations broadened emission control

requirements to include gaseous and

particulate emissions. The 1990

amendments to the Clean Air Act

required EPA to set more stringent

standards for NOX emissions from all

heavy-duty highway HDEs and for PM

from urban buses. 42 U.S.C. 7521(a)(3),

7521(f), and 7554(b).

The current exhaust emission

standards for highway heavy-duty diesel

and gasoline engines are presented in

Table 1. Standards for urban buses,

which specify more stringent PM levels

than those applying to other HDEs, are

displayed separately in the table.
33442 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

TABLE 1.—HIGHWAY HEAVY-DUTY EMISSION STANDARDS

Year HC (g/bhphr)

CO (g/bhphr)NOX (g/bhphr)

Diesel

particulate

(g/bhp-hr)

Diesel:

1991–93 ..................................................................................................................... 1.3 15.5 5.0 0.25

1994–97 ..................................................................................................................... 1.3 15.5 5.0 0.10

1998 ........................................................................................................................... 1.3 15.5 4.0 0.10

Urban Buses:

1991–92 ..................................................................................................................... 1.3 15.5 5.0 0.25

1993 ........................................................................................................................... 1.3 15.5 5.0 0.10

1994–95 ..................................................................................................................... 1.3 15.5 5.0 0.07

1996–97 ..................................................................................................................... 1.3 15.5 5.0 *0.05

1998 ........................................................................................................................... 1.3 15.5 4.0 *0.05

Otto-cycle HC

(g/bhp-hr)

CO

(g/bhp-hr)

NOX

(g/bhp-hr)

Evaporative

HC

(g/test)

1991–97:

(A) .............................................................................................................................. 1.1 14.4 5.0 3.0

(B) .............................................................................................................................. 1.9 37.1 5.0 4.0

1998 (A) ..................................................................................................................... 1.1 14.4 4.0 3.0

(B) .............................................................................................................................. 1.9 37.1 4.0 4.0

Note:

‘‘(A)’’ denotes the standard for engines in trucks ≤14,000 lbs. Gross Vehicle Weight Rating (GVWR).

‘‘(B)’’ denotes the standard for engines in trucks ≥14,000 lbs. GVWR.

*.07 g/bhp-hr in-use.

This table does not contain all applicable standards. A complete set of standards may be found in 40 CFR Part 86.

Under section 202(a)(3), emission

standards for highway HDEs are set at

the ‘‘greatest degree of emission

reduction achievable through the

application of technology which the

Administrator determines will be

available for the model year to which

such standards apply, giving

appropriate consideration to cost,

energy, and safety factors associated

with the application of such

technology’’ (42 U.S.C. 7521(a)(3)(A)). In

addition, section 202(a)(3) provides that

highway HDE manufacturers will have

four model years of lead time before any

new emission standards may be

implemented (42 U.S.C. 7521(a)(3)(C)).

The Act also provides that standards for

HDEs apply for at least three model

years to provide stability to any heavyduty standards. Id. Finally, the Act

precludes new NOX emission standards

for highway HDEs before the model year

2004. 42 U.S.C. 7521(b)(1)(C).

B. Description of Today’s Proposal

In this action, EPA proposes a

comprehensive program to address the

significant contribution of highway

HDEs to ambient pollutant

concentrations and the resultant air

quality problems around the country.

The proposed program consists of

stringent new emission standards,

changes to maintain the durability of

HDE emissions in use, and changes to

the current Averaging, Banking, and

Trading regulations to encourage the

early introduction of cleaner engines

and new technology.

1. Emission Standards

a. Standards Proposed in Today’s

Action. EPA proposes new emission

standards for model years 2004 and

later. These standards are in the form of

combined non-methane hydrocarbons

plus nitrogen oxides (NMHC + NOX)

and are presented in units of g/bhp-hr.

They would apply to otto and diesel

cycle engines fueled by gasoline, diesel,

methanol, and gaseous fuels and their

blends. Manufacturers would have the

choice of certifying their engines to

either of two optional sets of standards:

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 proposes that all other emission

standards and other requirements

applying to model year 1998 and later

model years remain unchanged.

For the most part, EPA expects that

either of these standards will result in

the essentially the same NOX and

NMHC emission rates in-use. As is

discussed elsewhere in the proposal and

in the supporting RIA, EPA expects that

the proposed standards will generally

result in NMHC levels of about 0.4 g/

bhp-hr and NOX levels of about 2.0 g/

bhp-hr. Most, but not all, HDEs now

have HC certification levels of 0.5 g/

bhp-hr or less. The standards will result

in modest NMHC reductions for the

HDE class taken as a whole and will

serve as a cap against increases in

NMHC emissions as manufacturers

implement NOX control strategies. The

expected NOX levels would result in

reductions of 50 percent as compared to

the 1998 standard. For administrative

simplicity, EPA would prefer only one

standard and based on current HC

certification levels the 2.4 g/bhp-hr

standard seems most appropriate.

However, the manufacturers would

prefer the flexibility of the alternate

standard and EPA sees no

environmental harm from offering this

option. EPA asks comment on whether

two standards are appropriate and why.

The form of the proposed standards

differs in some aspects from the current

and 1998 model year standards for

HDEs presented in Table 1. First, EPA

is proposing a combined standard

(NMHC+NOX) instead of separate

standards. EPA is using this approach

because for in-cylinder control strategies

there is a tradeoff between HC and NOX

control. Thus, expressing the

requirements as a combined standard

provides the manufacturers some small

amount of additional flexibility.

Further, EPA sees no environmental

harm from providing this flexibility.

While there is not a direct one to one

trade-off in every area of the country,

both pollutants are generally considered

key ingredients in the formation of

ozone. Thus a little more control of one

pollutant at the expense of the other

should provide essentially the same air

quality benefits as if the engines were

meeting separate standards for NOX and

NMHC at comparable levels (nominally

2.0 g/bhp-hr NOX and 0.4 g/bhp-hr

NMHC). Second, EPA is proposing an

NMHC standard instead of a total HC
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33443

standard. This approach is being

proposed primarily because methane is

largely unreactive in the formation of

ozone and thus its control would not

help to achieve the ozone air quality

objectives of this proposal. This is not

intended to suggest that the control of

methane is not valuable in the context

of other environmental objectives EPA

may consider in the future, but methane

emissions from these engines are only a

small fraction of their total HC and thus

foregoing control at this time is

reasonable. Both the use of an NMHC

standard and the use of a combined

standard is also consistent with the

current California LEV program

requirements for medium-duty vehicles

and the requirements for HDEs

prescribed in section 245 of the 1990

amendments to the Clean Air Act.

The proposed standards (rooted in the

California Federal Implementation Plan

and identified in the SOP) represent a

reduction of more than 50 percent in

NOX and NMHC/HC over current

requirements. Reductions of this

magnitude are a significant challenge,

especially for diesel HDEs, and will

require a major research and

development effort to achieve. At this

time there is not one firm set of

technologies to be applied to all diesel

HDEs to achieve the proposed

standards. Diesel HDEs will need to

consider approaches from a number of

different technological strategies and

control hardware which have been

identified and assessed in a few

laboratory programs and then apply

their choices to their 2004 models. In

many cases these strategies and

hardware have not been used on

production diesel engines and there are

substantial development challenges

ahead to apply this technology cost

effectively with due consideration to

impacts on operating and maintenance

costs as well as engine durability.

Regulatory enhancements such as the

proposed revisions to the Averaging,

Banking, and Trading program (as

discussed below) will also help to

enhance overall feasibility of the

standards for all engine models. As is

discussed elsewhere in proposal and in

the supporting RIA, EPA believes the

proposed standards while very

challenging are technically feasible and

otherwise appropriate in the context of

section 202(a)(3). With about eight years

remaining before the 2004 model year,

manufacturers have an unprecedented

amount of leadtime to fully assess,

develop, and optimize the various

control approaches and to integrate

them into their 2004 model year

products in a manner which minimizes

engine costs and fuel impacts and does

not raise safety concerns. Indeed the

widespread support of the HDE industry

for the SOP tends to support EPA’s

conclusion.

While there are promising

technologies and aftertreatment control

strategies which otto cycle (gasoline)

HDEs may employ to achieve the

proposed standards, these still require

development if they are to be applied to

all different otto-cycle engine models

and the standards are to be met in use.

EPA believes it will be easier

technologically for otto-cycle (gasoline)

HDEs to achieve the proposed standards

but proposes the same standards for otto

and diesel cycle HDEs for two reasons.

First, work is required to apply these

technologies/aftertreatment control

strategies to all otto cycle engines. EPA

expects that much of this progress will

be made in response to the 1998 HDE

NOX standard and others in response to

market competitive pressures.

Nonetheless, EPA still expects that some

models will need to develop and

employ technology/aftertreatment

control upgrades to meet a 2.4 g/bhp-hr

NMHC + NOX standard. This may

especially be the case for the few ottocycle HDE families which may not

employ closed loop control, fuel

injection systems with catalysts before

2004. Second, because otto and diesel

cycle HDEs compete in the market

place, there is a degree to which for

market equity reasons it is appropriate

to apply standards of equivalent

stringency to both classes of engines.

This approach reduces the possibility

that emission standards could have

disruptive effect on the HDE market.

Both EPA and the California Air

Resources Board have set HC and NOX

standards of equivalent stringency for

otto-cycle and diesel HDEs in the past.

b. 1999 Rulemaking Review

EPA proposes to conduct a special

review in 1999 to reassess the

appropriateness of the standards under

the CAA including the need for and the

technological and economic feasibility

of the standards at that time. Before

making a final decision in this review

regarding the appropriateness of these

standards under the CAA, EPA intends

to issue a proposal regarding this issue

and offer an opportunity for public

comment on whether the standards

continue to be technologically feasible

for implementation in 2004 and

consistent with the CAA. Following the

close of the comment period, EPA

would issue a final agency decision

under section 307 of the CAA.

If in 1999 EPA finds the standards to

not be feasible for model year 2004 or

otherwise not in accordance with the

Act, EPA will propose adjusted

standards which do not exceed the

following:

2.9 g/bhp-hr NMHC+ NOX

or

3.0 g/bhp-hr NMHC+ NOX with a limit

of 0.6 g/bhp-hr on NMHC.

However, if EPA determines that the

feasibility of the standards requires

diesel fuel changes and EPA does not

engage in rulemaking to require such

changes, EPA will propose adjusted

standards which do not exceed the

following:

3.4 g/bhp-hr NMHC + NOX

or

3.5 g/bhp-hr NMHC + NOX with a limit

of 0.7 g/bhp-hr on NMHC.

The standards finalized in the

rulemaking initiated by today’s proposal

would stay in effect unless revised by

this subsequent rulemaking procedure.

EPA has included language in the

proposed regulatory text regarding the

1999 review.

Over the next several years EPA will

be actively engaged in programs to

evaluate technology (engine/fuel

quality) interactions/developments and

progress toward meeting the proposed

standards through in-house programs

and coordination with the involved

industries. To aid in this process EPA

has established a working group under

its Mobile Sources Technical Advisory

Sub-Committee to the CAA Advisory

Committee to solicit technical advice

and input from engine, fuel, and related

experts from around the country. If as a

result of this evaluation, EPA reaches

the view that the available information

is sufficient to indicate that the

feasibility of the standards may depend

on modifications to diesel fuel, any

potential for diesel fuel changes could

then be considered within the context of

the 1999 Review. EPA recognizes that

any consideration of potential fuel

diesel modifications must be

appropriate under section 211(c) of the

CAA (including considerations of cost,

cost effectiveness, and other relevant

cost considerations), and is especially

sensitive to the substantial leadtime

requirements that may be associated

with fuel modifications.

Based on the information presented in

the RIA and in section IV of this

proposal, EPA believes the proposed

standards are technologically feasible

and otherwise appropriate under the

CAA. Nonetheless, especially for diesel

engines, it is clear that a significant

amount of research and development

will be needed to comply. The alternate

standards discussed above are designed

to serve as a backstop in the event that
33444 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

the 1999 review leads to the conclusion

that a revision is appropriate. Based on

the technical analysis in the RIA, these

levels represent upper limits for these

potential revisions. If during the course

of the review EPA concludes that a

revision is appropriate, a rulemaking

will be conducted to determine the

appropriate level for the model year

2004 and later standards.

c. Other Issues Related to HDE

Emission Standards. Several

commenters to the ANPRM expressed

concern with the levels of the emission

standards EPA is proposing today.

Representatives of environmental

organizations and several states argued

that EPA should propose more stringent

standards for one or more pollutants.

While EPA believes at this time that

today’s proposed program represents the

best combination of standards that are

achievable given our current

understanding of technological

constraints, as explained below, and the

other criteria set forth in CAA section

202(a)(3), EPA remains open to

additional information and will

consider finalizing more stringent

standards in this action or proposing

more stringent standards by separate

action if such standards are warranted.

In comments the Agency has received

thus far, commenters generally address

potential standards for NOX and PM

separately and somewhat

independently. These comments urge

the Agency to propose an NMHC + NOX

standard low enough to assure that NOX

levels of 2.0 g/bhp-hr are reached by all

diesels, expressing concern that a 2.4 or

2.5 g/bhp-hr NMHC + NOX standard

will actually translate into 2.2–2.3 g/

bhp-hr NOX, not the 2.0 g/bhp-hr level

applied in the California Federal

Implementation Plan (FIP) to model

year 2002 engines. These commenters

also suggest that a PM standard of 0.05

g/bhp-hr be proposed, equal to the level

which currently applies to urban buses.

The Agency believes that because of

the close interaction among NOX,

NMHC, and PM emissions from diesel

engines, decisions about proposed

emission standards cannot be made

independently from one another. As

described below in section IV, EPA

believes that reaching all the standards

proposed today simultaneously will

require a very large technological effort

on the part of diesel HDE

manufacturers. Based on the

information available today, the Agency

believes that the scale of the effort

which will be required is such that if

NOX, NMHC, or PM standards lower

than those proposed here were to be

required, the feasibility of implementing

the program for the 2004 model year

would be threatened. That is, while

manufacturers may be able to achieve

lower emission levels for some engine

models, at this time EPA does not

believe that this would be feasible, on

average, for the full line of engines

manufacturers will likely be offering in

2004. (The technological assessment on

which EPA based a 2.0 g/bhp-hr NOX

emission standard in the California

Federal Implementation Plans assumed

that only engines sold in California, not

all engines nationally, would be

affected.) Regarding a specific comment

that a combined NOX + NMHC standard

allows NOX emissions significantly

higher than the 2.0 g/bhp-hr NOX goal,

the Agency accepts the intention of the

engine industry to reach levels very

close to 2.0 g/bhp-hr. This also seems

likely from a technical perspective since

at best modest NMHC reductions can be

achieved over current levels. By

combining the NOX standard with

NMHC, EPA proposes to allow a small

degree of flexibility to manufacturers

which succeed in achieving very low

NMHC levels in conjunction with the

proposed NOX and PM standards.

However, the Agency does not expect

that the opportunity to take advantage of

that flexibility will be frequently used

and expects that on average in-use NOX

levels would be approximately 2 g/BHPhr.

As is the case for NMHC, for many incylinder control strategies there is a

trade-off between NOX and PM emission

rates. In-cylinder techniques which

reduce NOX may increase PM and viceversa. For HDDEs, EPA expects that

most manufacturers will rely on incylinder NOX control techniques as

opposed to aftertreatment devices. Some

of these techniques are likely to put

upward pressure on PM levels, and thus

will require special optimization to

ensure that PM levels are not increased.

A simultaneous reduction in the PM

standard could have an adverse effect

on the feasibility of the NMHC + NOX

standard. Nonetheless, EPA recognizes

the need for and value of additional

reductions in PM emission rates and

asks for comments on this matter.

EPA encourages further, detailed

comment on the appropriateness of the

proposed levels for NMHC + NOX and

PM in light of the technological

interactions of their formation and

control. EPA will consider finalizing

standards different than those proposed

today to the degree that comments and

analysis support such action. However,

the interactions among the pollutants

would require a reassessment of all

pollutants if a more stringent standard

is to be considered for any one

pollutant.

One commenter requested that EPA

propose voluntary low emission

standards for NOX and PM which would

apply between 1998 and 2003 at levels

below the 4.0 g/bhp-hr NOX and 0.10 g/

bhp-hr PM which would be required in

2004. The ultimate purchasers of HDEs

certified to meet the voluntary low

emission standards would be able to

market the emission credits generated.

EPA asks for comment on the need for

and desirability of lower voluntary NOX

and PM standards as a means to

encourage technological innovation and

the value of such a program given that

manufacturers can already elect to

certify to lower standards (family

emission limits) under the Averaging,

Banking, and Trading (A,B,&T) program.

These extra emission reductions from

these HDEs could be sold for marketable

credits provided there is not double

counting between the A,B,&T program

and a user program.

Commenters also raised the issue of

whether standards for otto-cycle HDEs

(gasoline-fueled) should be different,

and more stringent, than those for

diesel-cycle HDEs. As commenters

observe, the technological challenge of

achieving lower NOX levels

simultaneously with low NMHC levels

has been less for otto- than diesel-cycle

HDEs in the past and current data

suggests this may be the case for the

proposed 2004 standards. In 1996 there

were seven otto-cycle HDE families that

certified to the existing standards with

combined NMHC+NOX levels below the

level of the proposed NMHC+NOX

standard. However, of these seven, only

about half had actual test data to

demonstrate emission levels which

could allow them to certify to the level

of the proposed standards. Durability

test data on others indicates that they

would be unable to meet a 2.4 g/BHPhr NMHC+NOX standard at the end of

their useful life period.

Lower certification levels for some

families does not necessarily lead to the

conclusion that levels significantly less

than the proposed standards are

achievable by all families in the near

term. Indeed, the industry has raised

concern that even if the level of the

proposed standard can be achieved on

laboratory prototypes in the near term,

some engine models will require

additional work to gain the additional

emission reductions needed to account

for the effects of production and test

variability and the deterioration in the

efficiency of emission controls in use.

Industry has suggested that a prototype

engine emission rate about 1 g/BHP-hr

less than the proposed standard is

needed to be assured of compliance by

production engines.
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33445

Nonetheless, the recent engine and

emission control system improvements

and the resultant reduction in the

NMHC+NOX emission levels of many of

the current otto-cycle families clearly

indicate that the proposed standards are

feasible by the 2004 model year. Some

concern has been expressed that the

proposed standard may be more

difficult for otto-cycle engines used in

heavier vehicles (>14,000 lbs GVWR). If

not formulated properly, the efficiency

of their catalysts may be reduced by

heat stress which occurs during the

longer periods of high load operation

which are characteristic of some of these

vehicles. However, the fact that ottocycle HDEs with these lower emission

rates are used in vehicles of all weight

classes suggests that vehicle design and

use patterns do not govern the

feasibility of low NOX catalyst

technology. EPA believes that any

technological feasibility concerns for

otto-cycle HDE families required to meet

the proposed standard can be resolved

within the next eight years.

Given the relatively low NMHC+NOX

certification levels of some current ottocycle engines and the available

leadtime, EPA requests comment on

setting the NMHC+NOX standard for

otto-cycle engines in the range of 1.5–

2.0 g/BHP-hr. In addition to comments

on technological feasibility, EPA

requests comment on the

appropriateness of a lower standard in

the context of emission inventory

benefits, environmental need, costs of

compliance (purchase and operating),

energy impact, safety, and market equity

concerns. Comments regarding market

equity should address how different

levels of NMHC+NOX standards for ottoand diesel-cycle engines would affect

the market relationship between these

technologies. EPA also requests

comment on whether implementing a

separate standard for otto-cycle engines

(which are largely gasoline-fueled

engines) would be an appropriate

change from the historical ‘‘fuel

neutral’’ nature of EPA’s emission

standards for NMHC and NOX emissions

from HDEs, and whether such a change

could adversely affect the development

of and use of clean alternative fuels.

EPA also requests comment on

another alternative approach for ottocycle engines. Under this approach,

manufacturers could voluntarily elect to

certify these engines to the proposed

standard significantly earlier (i.e., model

year 1999, 2000, or 2001 instead of

2004) as an alternative to meeting the

more stringent standard discussed above

(1.5–2.0 g/bhp-hr) in 2004. In this

concept, the more stringent 2004

standard for otto-cycle engines either

would not apply or would apply to a

model year after 2004 to a manufacturer

that elected to meet the proposed

standard early. This approach would

have the benefit of providing early

emission reductions and, to the extent

that manufacturers choose the proposed

standard early, would help reduce the

potential market equity impacts

mentioned above since the same

standard would apply to both otto- and

diesel-cycle engines. While EPA may

not impose on highway heavy-duty

engines NOX standards more stringent

than 4.0 g/bhp-hr for any model year

before 2004 (CAA sections 202(b)(1)(C)

and (a)(3)(B)(ii)), EPA believes it retains

authority to offer manufacturers the

voluntary option of complying with a

NOX plus NMHC standard of 2.4 g/bhphr beginning before model year 2004.

EPA requests comment on the

appropriateness of finalizing this

concept. Should a commenter favor this

concept, they should specify the version

they prefer (i.e., implementation date of

the 2.4 g/BHP-hr standard or

implementation date and numerical

value of a later more stringent standard.

EPA seeks comment on the technical

feasibility and appropriateness in the

context of environmental need, costs of

compliance, energy impact, safety and

market equity for the option supported.

The public docket contains a memo

further discussing each of the

alternative approaches to otto-cycle

HDE standards as laid out above.

Finally, several commenters

encouraged EPA to reconsider the role

of alternative fuel technologies in

reaching low emission levels. EPA

believes HDE technologies using

alternative fuels can reach or exceed the

emission standards proposed today. For

this reason, EPA has for many years

supported, and continues to support,

expanded use of optimized alternative

fuel engines. The Agency is pleased that

development of HDEs which use

alternative fuels is continuing and that

some of these engines have been

marketed, usually for specialized

purposes. However, it does not appear

that a major shift in the market toward

alternative fuel HDEs is underway, and

EPA does not believe at this time that

the HDE manufacturing industry is in a

position to shift a significant amount of

its production toward non-petroleum

fuels by the year 2004. Thus, EPA

believes it is likely that petroleumfueled HDEs will continue to dominate

the HDE industry well into the next

century, and the Agency does not

believe that EPA action that could

theoretically force a faster shift toward

alternative fuel technologies (e.g.,

extremely low emission requirements

for all engines) would be effective in the

absence of a strong market demand for

such engines.

Therefore, the Agency believes that it

is appropriate to base new proposed

HDE emission standards on the

projected capabilities of petroleumfueled engines rather than on the

current or projected capabilities of

alternative fuel engine technologies. If

the stringent standards proposed today,

while achievable by petroleum-fueled

engines, are indeed relatively easy for

some alternative fueled engines to meet,

the result may be the introduction of

alternative fueled HDEs that are both

acceptable to the market and priced

competitively. From the Agency’s

perspective, such a market-based

promotion of alternative fuel

technologies would be a positive result

of today’s proposed action.

d. Non-conformance Penalties.

Section 206(g) of the Clean Air Act

requires EPA to allow an HDE

manufacturer to receive a certificate of

compliance for an engine family which

exceeds the applicable standard (but

does not exceed an upper limit) if the

manufacturer pays a non-conformance

penalty established by EPA through

rulemaking. The NCP program

established through rulemaking is

codified in Subpart L of 40 CFR 86. EPA

plans to address provisions related to

NCPs for the proposed 2004 model year

standards in conjunction with the 1999

review discussed above.

2. In-use Emissions Control Elements

a. Introduction. Historically, EPA has

viewed in-use emissions deterioration

as a problem associated more with

gasoline engines than with diesel

engines. For NOX emissions, EPA has

tended to be less concerned with diesel

engine emissions deterioration because

diesels are currently equipped with

fewer aftertreatment or other emission

control devices susceptible to in-use

degradation. Diesel engine emissions

standards have historically been met

mainly through overall improvements to

the engine and fuel system. These

improvements have resulted in

improved performance, fuel economy,

and durability as well.

As described below in Section IV. A.,

as standards are reduced diesel HDE

manufacturers will likely continue to

strive to meet the standards through

engine, air intake, and fuel systems

redesign. However, they may find it

necessary to introduce new

technologies, such as exhaust gas

recirculation (EGR), which function

solely to reduce emissions. Long-term

emissions performance becomes a
33446 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

31 40 CFR 86.096–2. The Clean Air Act

Amendments of 1990 specify a minimum useful life

years limit of ten years for heavy-duty engines with

respect to any standard that first becomes

applicable after the 1990 amendments were

enacted. 42 U.S.C. 7521 (d)(2). Standards adopted

after the Amendments such as the urban bus

particulate standard and the 1998 and later model

year NOX standard have a useful life years limit of

ten years (e.g., 40 CFR 86.098–2). Standards

adopted before the Clean Air Act Amendments of

1990 have a useful life years limit of eight years.

32Comments of American Trucking Association,

Inc., October 17, 1995, Docket A–95–27, II–D–40.

greater concern with the addition of

such emissions control technologies.

The controls may not function as long

as the engines and there may be little

incentive for vehicle owners to conduct

the repairs on these items needed to

ensure emissions control during the

very long life of the engines. This is of

particular concern because the heavyduty engine market has demanded

longer-lasting engines, and

manufacturers have been successful in

increasing engine life. It is EPA’s

understanding that some current large

engines accumulate in excess of 500,000

miles before being rebuilt and are used

for several hundred thousand more

miles after rebuild. Thus, failure of

emissions controls early in the engine’s

life could offset a significant portion of

the expected benefit associated with the

more stringent standards proposed

today.

As described below, EPA is proposing

revisions to its current regulations

regarding in-use emissions control

including changes to useful life,

emissions related maintenance and

warranty provisions. These changes are

intended as updates to current

requirements which will further

encourage engine manufacturers to use

emissions controls that will have a high

degree of durability, and that perform

well in use without an unreasonable

degree of owner involvement. EPA is

also proposing other basic provisions to

help encourage the maintenance and

repair of emissions controls after the

regulatory useful life is reached, and

especially during engine rebuild. The

proposals would be effective beginning

with 2004 model year engines. EPA

believes that the industry is fully

capable of responding to the challenge

of achieving the benefits of low

emissions standards, not just in the

early years of engine life, but throughout

the time that the engine is in-use. EPA

requests detailed comments, with as

much supporting rationale as possible,

on all of the following proposals.

b. Revisions to Current Regulations

To help ensure the durability of new

emissions related technology used to

meet the new standards, EPA is

proposing revisions to its current

regulations in the areas of ‘‘useful life’’,

‘‘emissions related maintenance’’, and

‘‘emission defect and performance

warranties’’.

i. Useful life

As provided in section 202 of the

Clean Air Act, EPA specifies the ‘‘useful

life’’ periods for the various heavy-duty

engine types. The regulatory useful life

is the period of time or operation during

which manufacturers are liable for

emissions compliance. Manufacturers

are responsible for making sure their

engines meet emissions standards not

just at the time of certification and

production but also for the regulatory

useful life of the engines. EPA has the

authority to test engines selected from

the production line and from the in-use

fleet to determine compliance with this

requirement. EPA can require

manufacturers to recall and repair

engines in an engine family if testing of

properly maintained and used engines

or other information indicates that a

substantial number of engines in the

engine family do not meet emissions

standards during the useful life. EPA’s

ongoing programs for production-line

auditing (Selective Enforcement

Auditing) and in-use recall are two

primary EPA enforcement mechanisms

for engine emissions standards. The

statutory authority for these programs is

found in Sections 206 and 207 of the

Clean Air Act.

Currently for heavy-duty on-highway

engines, the useful life is generally

defined as eight years or 110,000 miles

for light heavy-duty diesel engines

(HDDEs) and gasoline heavy-duty

engines, eight years or 185,000 miles for

medium HDDEs, and eight years or

290,000 miles for heavy HDDEs,

whichever comes first.31 These mileage

values were originally chosen to roughly

correspond to the prevailing average

engine lives before retirement (for

smaller engines) or major engine

rebuilds (for larger engines). Since the

middle 1980s, manufacturers have

increased very significantly the

mechanical durability of heavy-duty

diesel engines, allowing the engines to

go many more miles before rebuild.

Also, the annual vehicle miles travelled

(VMT) for newer line-haul trucks has

increased which results in the trucks

reaching the end of their defined useful

life more quickly. It is not uncommon

for line haul trucks to reach their

current maximum useful life of 290,000

miles well before the years useful life

interval.

The first part of the following

discussion concerns the mileage portion

of the useful life. The years useful life

interval is much less critical because it

is not generally the limiting interval.

EPA is proposing to make the years

portion consistent at ten years for all

heavy-duty engines and standards

beginning with the 2004 model year.

The discussion of the years interval

proposal follows the proposals and

discussion regarding mileage.

The engines of greatest concern to

EPA are those in the heavy heavy-duty

diesel engine category because they, for

the most part, are the engines that tend

to reach the end of the useful life

quickly and then continue to

accumulate many more miles than the

current useful life before needing to be

rebuilt. Published warranty information

indicates that the major engine

components of heavy HDDEs are

warranted for 500,000 miles in most

cases and extended base engine

coverage is often available for up to 5

years/500,000 miles. Since the repair or

replacement of some of the components

covered by the warranties due to wear

is fundamental to rebuilding, the

warranties are one good indication that

some engines greatly exceed EPA’s

current useful life miles limit of 290,000

miles. Also, it is commonly accepted in

the trucking industry that, with sound

maintenance practices, today’s heavy

HDDEs last much longer than 290,000

miles before rebuild.32

Although EPA could perhaps justify

proposing an increase of the heavy

HDDE useful life requirement to 500,000

miles or more based on how long

engines are lasting today before rebuild,

EPA believes that a somewhat lower

value is appropriate. Engine

manufacturers have stated that they will

be challenged to meet the proposed new

standards and an extremely long useful

life could affect the feasibility of the

2004 standards. EPA acknowledges that

the length of the useful life can affect

the feasibility of the standards. EPA

believes that the program goal of

ensuring durable emissions control

designs would be achieved through a 50

percent increase in the useful life up to

435,000 miles. This value represents a

meaningful increase in the useful life

without potentially compromising the

feasibility or cost effectiveness of the

2004 standards. Additionally, other

programs, as described below, can help

ensure emissions controls continue to

operate properly after the end of the

useful life. The end of the useful life

does not necessarily mean the end of

good in-use emissions performance.

Not all heavy HDDEs are used in linehaul trucks which accumulate miles

very quickly. A small minority of heavy
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33447

33 ‘‘National Transit Summaries and Trends For

the 1993 National Transit Database Section 15

Report’’, Federal Transit Administration, May 1995.

34 ‘‘Data Tables For the National Transit Database

Section 15 Report Year’’, Federal Transit

Administration, December 1994.

35 40 CFR 86.094–25 (b)(4) contains several hours

and miles equivalents for HDDEs all of which are

based on the ratio of one hour to 33.3 miles of

operation.

HDDEs are used in urban (transit) buses

and other urban vehicles that

accumulate miles much more slowly.

For example, urban buses average about

13 miles per hour (including idle

time) 33 and about 40,000 miles per

year.34 For urban vehicles such as urban

buses, a useful life of 435,000 miles

would be excessive because of their

slow mileage accumulation rates. EPA

has addressed such concerns in other

regulations by adopting an hours limit

that is equivalent to a miles limit which

is set to reflect typical operation of

heavy-duty engines. Vehicles that

accumulate mileage more slowly than

typical for heavy-duty vehicles would

reach the hours interval before the

mileage interval. In keeping with this

approach, EPA proposes to add an hours

limit of 13,000 hours to the useful life

for heavy HDDEs. The 13,000 hours

limit is based on other hours and miles

equivalents used in existing EPA

regulations regarding heavy-duty

engines.35

EPA, however, is concerned that the

hours interval being proposed could, in

effect, relax the useful life from its

current level, as would be the case in

instances when vehicles would reach

13,000 hours before reaching 290,000

miles. Given the average speed for urban

buses of 13 miles per hour, this would

be likely to occur frequently. To ensure

that the addition of an hours limit does

not result in a useful life less than the

current useful life in any instance, EPA

proposes not to allow the hours limit to

be effective until after an engine reaches

290,000 miles. In summary, EPA

proposes a useful life for heavy HDDEs

of 435,000 miles, 13,000 hours, or ten

years, whichever occurs first, but in no

case less than 290,000 miles.

EPA requests comments on two

alternative approaches to adopting an

hours limit of 13,000 hours. The first

option is to not have an hours interval

and retain the useful life mileage

interval of 290,000 miles for urban bus

engines with an increase of the mileage

interval to 435,000 miles for all other

heavy HDDEs. This would simplify

regulations but could disadvantage

engine manufacturers where engines are

used in slow moving urban vehicles

other than urban buses, such as solid

waste haulers. The second option is to

set the hours interval to be equivalent to

the number of hours it takes an urban

bus, on average, to accumulate 290,000

miles. Using the 13 miles per hour

estimate from above, the hours interval

would be 22,300 hours. With this

second option, EPA also requests

comments on whether or not a

minimum useful life of 290,000 miles is

appropriate. These two alternatives may

work well for urban buses but may not

be as appropriate for other urban heavyduty vehicles.

Currently the years component of the

useful life is eight years for some

standards and ten years for others

depending on whether the standards

were adopted before or after the Clean

Air Act Amendments of 1990. Standards

promulgated after the Clean Air Act

Amendments, such as the 1998 4.0 g/

bhp-hr NOX standard, are required to

have a useful life years limit of 10 years.

EPA proposes to make the useful life

years limits consistent for all pollutants

and for all heavy-duty engines by

raising the years component of the

useful life so that it is ten years in all

cases. The change affects the carbon

monoxide and particulate matter

standards (except the urban bus

particulate standards which are already

at ten years). EPA regards this change as

a simplification of the regulations with

very little or no impact on the

stringency of the standards because EPA

believes that vehicles will reach the

mileage limits before the years limits in

almost all cases.

EPA requests comments on the

appropriateness of the useful life

proposals described above. In particular,

EPA seeks comments on the

appropriateness of the 435,000 mileage

limit, the appropriateness of treating

engines used in urban vehicles

differently from other heavy HDDEs,

and the appropriateness of the proposed

13,000 hour limit.

ii. Emissions-Related Maintenance

The frequency of emission-related

maintenance actions that manufacturers

require owners to perform as a

condition of their emissions warranties

is another issue that affects the actual

in-use emission performance of engines.

If such required maintenance is more

than the vehicle owner is likely to

perform due to cost or inconvenience,

then in-use emissions deterioration can

result. Therefore, EPA currently

imposes limits on the frequency of

maintenance that can be required of

HDE owners for emissions related items.

These limits also apply to the engine

manufacturer during engine certification

and durability testing. The requirements

currently apply for the useful life of the

engine. Table 2 summarizes current

regulations regarding the mileage

interval limitations for the maintenance

manufacturers may specify on certain

emissions-related items for heavy-duty

diesel engines (HDDEs). Engine

manufacturers cannot require

maintenance to be performed any more

often than is noted in the table but may

specify longer periods. The intervals are

in miles or hours, whichever occurs

first.

TABLE 2.—CURRENT INTERVALS FOR EMISSION-RELATED MAINTENANCE 1

50,000 miles or 1,500 hours for all

heavy duty diesel engines

(HDDEs).

100,000 miles or 3,000 hours for

Light HDDEs.

150,000 miles or 4,500 hours for

Medium and Heavy HDDEs.

None listed.

EGR systems including all related filters and control valves 2.Turbocharger .................................... Turbocharger .................................... Catalytic converter.2

PCV valve 2 ....................................... Fuel injectors .................................... Fuel injectors ....................................

Fuel injector tip cleaning .................. Electronic engine control unit, sensors, and actuators 2.Electronic engine control unit, sensors, and actuators 2.

Particulate trap 2 ............................... Particulate trap 2 ...............................

1Source 40 CFR 86.094–25.

2 Critical emissions-related components.

Table 2 notes components that EPA

considers ‘‘critical emissions-related

components’’ and EPA has additional

requirements for these components (see

40 CFR 86.094–25 (b) (6)). Specifically,

manufacturers must show that
33448 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

36While EPA is proposing to revise the

performance warranty period as discussed below, in

accordance with Section 207(i) of the Clean Air Act,

EPA has not prescribed regulations under Section

207(b)(2) of the Act which require heavy-duty

engine manufacturers to provide performance

warranties.

37Useful life definition paragraph (6), 40 CFR Part

86.096–2.

maintenance which the manufacturer

requires for a critical emission-related

component has a reasonable likelihood

of being performed by the operator in

use. The engine manufacturer has a

variety of options for making such a

demonstration such as showing that

component degradation will also cause

vehicle performance to degrade or by

using visual displays to notify the driver

that maintenance is needed.

EPA believes that revising the

maintenance intervals for certain

technologies is appropriate in order to

adequately cover the technologies

which manufacturers may use to meet

the proposed 2004 and later model year

standards. The new standards may

prompt the use of EGR on heavy-duty

diesel engines and an increased interval

for EGR valves and tubing will help

ensure adequate system durability.

Similarly, EPA believes that catalytic

converters should be added to the list of

emission-related components for HDDEs

for which a minimum interval is

specified, also to ensure adequate

durability. Except for the recent use of

catalytic converters for particulate

control, neither technology has been

used significantly for HDDEs in the past.

Accordingly, EPA proposes for EGR

valves and tubing and catalytic

converters that manufacturers specify

maintenance no more often than the

intervals shown in Table 2 for other

technologies; 100,000 miles or 3,000

hours, whichever occurs first, for light

HDDEs and 150,000 miles or 4,500

hours for medium and heavy HDDEs.

For EGR system filters and coolers, EPA

proposes that the maintenance interval

would remain 50,000 miles/1,500 hours

due to manufacturer concerns that a

longer interval for these components

may not be feasible.

In addition, there is the possibility

that new technologies not listed in

Table 2 could be used to meet the

proposed standards. Therefore, EPA

proposes to apply the same maintenance

intervals as listed above for most

components, 100,000 miles or 3,000

hours, whichever occurs first, for light

HDDEs and 150,000 miles or 4,500

hours for medium and heavy HDDE, to

any additional add-on emissions-related

components that manufacturers

introduce in the future. EPA proposes to

define add-on emission-related

components for this purpose as

components whose sole or primary

purpose is to reduce emissions or whose

failure will significantly degrade

emissions control and whose function is

not integral to the design or

performance of the engine. EPA would

also consider such components critical

emission-related components for

purposes of 40 CFR 86.094–25(b)(6).

EPA believes that this proposal is

necessary to provide the same minimum

level of durability for all emissionsrelated components (except EGR filters

and coolers) used to meet the standards.

The minimum requirement will also be

helpful in the development of future

technologies as it will provide a clear

minimum design target for technology

development.

Maintenance requirements for

gasoline-fueled heavy-duty engines and

light heavy-duty diesel engines are

currently the same for EGR and several

other components due to the similarity

in their duty cycles. EPA believes that

it is appropriate for the maintenance

intervals for EGR for light heavy-duty

diesel engines and heavy-duty gasoline

engine to remain consistent with each

other given this similarity. Therefore,

for otto-cycle (i.e., gasoline-fueled)

heavy-duty engines, EPA proposes that

the maintenance interval for EGR valves

and tubing be increased to 100,000

miles or 3,000 hours from the current

50,000 mile or 1,500 hour interval.

Because gasoline-fueled engines emit

less particulate (which can cause

deterioration of the EGR system) than do

diesel engines, EPA does not believe

that the change represents a particular

challenge for gasoline-fueled engines.

EPA requests comments on the

proposed changes to the maintenance

intervals described above including

comments on the length of the intervals

and the technologies for which intervals

are being proposed. Also, EPA requests

comment on the definition of ‘‘add-on

emission-related component’’ offered

here.

iii. Emissions Defect and Performance

Warranties

Emissions warranties are provided by

manufacturers as required under

Section 207 of the Clean Air Act. The

performance warranty provides that if a

properly maintained vehicle or engine

fails to conform to EPA emissions

requirements at anytime during the

warranty period, and such

nonconformity causes the owner to have

to bear a penalty or other sanction, then

the engine manufacturer is responsible

for remedying the nonconformity at its

own cost.36 The defect warranty

provides that manufacturers are

responsible for defects in materials and

workmanship which cause an engine

not to conform with applicable

regulations. EPA currently requires that

the emission defect and emission

performance warranties for heavy-duty

gasoline engines and light HDDEs last 5

years/50,000 miles and for medium and

heavy HDDEs last 5 years/100,000

miles, whichever occurs first, but in no

case may the warranty period be less

than the manufacturer’s basic

mechanical warranty period for the

engine family.37

EPA proposes to clarify that the

period of the warranty is to be in no

case less than the basic mechanical

warranty period that the manufacturer

provides to the purchaser with the

engine rather than the general warranty

period for the engine family. It is

common for manufacturers to provide

negotiated mechanical warranties that

are longer than the published base

warranties for the engine family. EPA

believes that this modification is

appropriate because negotiated

warranties are prevalent and therefore

the published warranty is not reflective

of the true mechanical warranty period

in many cases. EPA requests comments

on this proposal.

c. Maintenance and Repair of Emissions

Controls After the End of the Useful Life

As discussed above, EPA regulates

maintenance and repairs of emissions

control components that manufacturers

may specify during the useful life of the

engines. However, these provisions will

not ensure emissions control for the full

operating life of all heavy-duty engines.

Large diesel engines have an extremely

long life that is extended through

rebuilding. If the vehicle owner and

engine rebuilder were to not properly

maintain or repair emissions control

components, the controls could degrade

and cause an unacceptable increase in

emissions. Because there may be no

effect on engine performance, the

degraded components may otherwise go

unnoticed for a significant portion of the

total life of the engine. Since HDEs are

typically rebuilt, EPA also believes it is

appropriate to take steps to ensure that

emissions-related components used to

meet the new standards receive all

needed maintenance and repair beyond

the useful life period. The proposals

described below fall into two categories:

manufacturer requirements and engine

rebuilding requirements. The proposals

are intended to help enhance the focus

on emissions-related components and

the Agency does not believe that the

proposals will result in significant costs

above those that would be incurred for
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33449

38 40 CFR 86.094–25(b)(6)(ii)(C) 39 40 CFR 86.094–25(b)(6)(iii)

40 40 CFR Part 85, Subpart O, Urban Bus Rebuild

Requirements.

41 ‘‘Heavy-duty Engine Rebuilding Practices,’’

EPA Final Report by Tom Stricker and Karl Simon,

March 21, 1995.

42EPA Docket A–95–27, Docket II-D–41.

the proper maintenance/repair of

emissions-related components. As with

the related provisions proposed above,

EPA believes that these basic provisions

are necessary beginning with the 2004

model year because new add-on

emissions-related components which

may require occasional maintenance

and repair may be used to meet the 2004

and later model year standards.

i. Provisions Affecting Manufacturers

Manufacturers currently provide

owners with comprehensive service/

maintenance manuals covering the

maintenance necessary to keep engines

operating properly. If a manufacturer

required maintenance on any emissionsrelated components during the useful

life, as described above in 2.b.ii. of this

section, maintenance procedures would

be detailed in this manual. EPA

proposes to require that manufacturers,

in addition, include in the manual

maintenance needed for emissions

related components after the end of the

regulatory useful life, including

mileage/hours intervals and procedures

to determine whether maintenance or

repair is needed. The recommended

practices must also include instructions

for accessing and responding to any

emissions-related diagnostic codes that

may be stored in on-board monitoring

systems. The recommended

maintenance practices would be based

on engineering analysis or other sound

technical rationale. In the event that an

emission-related component is designed

not to need maintenance during the full

life of the vehicle, the manual would

need to contain at a minimum a

description of the component noting its

purpose and a statement that the

component is expected to last the life of

the vehicle without maintenance or

repair. In addition, manufacturers

would be required to highlight in the

manual any rebuild provisions adopted

by the Agency, as described in 2.c.ii.

below, to ensure that owners and

rebuilders are aware of the

requirements.

As described above in 2.b.ii. of this

section, manufacturers must ensure that

critical emissions-related scheduled

maintenance has a reasonable likelihood

of being performed in-use.

Manufacturers may elect to provide

such assurance by using some form of

on-board driver notification when

maintenance is needed on a critical

emission related component.38 The

signal may be triggered either based on

mileage intervals or component failure.

It is currently considered a violation of

the Clean Air Act’s prohibition on

tampering (Section 203(a)(3)) to disable

or reset the signal without also

performing the indicated maintenance

procedure.39

EPA proposes to require that

manufacturers electing to use such

signal systems to ensure that critical

emissions-related maintenance has a

reasonable likelihood of being

performed must design the systems so

that they do not cease to function at or

beyond the end of the regulatory useful

life. For example, if the signal is

designed to be actuated based on

mileage intervals, it would have to be

designed to continue to signal the driver

at the same intervals after the end of the

useful life. EPA does not propose,

however, to hold the manufacturer

responsible or liable for recall due to

signal failure in instances where the

signal fails to function as designed

beyond the end of the useful life.

Manufacturer recall liability is limited

to failures during the regulatory useful

life under Section 207 of the Clean Air

Act. (The manufacturer is also not

responsible for repairs when the signal

does function after the end of the useful

life unless such repairs are covered by

the emission warranty provided as

described above in 2.b.ii.)

EPA believes these proposals will

help ensure that information necessary

to care for critical emission related

components through the engines’ entire

life on the road will be widely available

to owners, rebuilders and others

maintaining and repairing heavy-duty

engines. EPA requests comments on the

proposals.

ii. Provisions Pertaining to Engine

Rebuilding Practices

EPA has two concerns regarding the

rebuilding of 2004 and later model year

engines, both related to new emissions

related components that may be added

to the engine to meet the new standards.

First, EPA is concerned that during

engine rebuilding, there may not be an

incentive to check and repair emissions

controls that do not affect engine

performance. Second, EPA is concerned

that there may be an incentive to rebuild

engines to a pre-2004 model year

configuration due to real or perceived

performance penalties associated with

2004 and later model year technologies.

Such practices would likely result in a

loss of emissions control.

EPA currently does not have

regulations concerning engine

rebuilding practices for heavy-duty

engines other than requirements for

engines used in 1993 and earlier model

year urban buses.40 Clean Air Act

Section 202(a)(3)(D) directed EPA to

study heavy-duty engine rebuild

practices and the impact rebuilding has

on engine emissions. Based on the study

and other information, EPA may

prescribe requirements to control

rebuilding practices (whether or not the

engine is past its useful life), which in

the Administrator’s judgement cause, or

contribute to, air pollution which may

reasonably be anticipated to endanger

public health or welfare taking costs

into account. 42 U.S.C. 7521 (a)(3)(D).

EPA conducted a study of engine

rebuilding and determined that currenttechnology engines, when rebuilt,

generally emit at levels near or below

the certification standards that applied

to the engine when new and that

regulations to control rebuild practices

did not appear to be warranted at that

time.41

In the ANPRM, EPA requested

comments on establishing rebuild

requirements to promote continued inuse compliance for 2004 and later

model year engines. The Automotive

Engine Rebuilders Association (AERA)

and other related associations stated in

their comments on the ANPRM that it

is extremely unlikely that engine

rebuilders would rebuild to non-original

specifications because such a product

would not be acceptable to the

purchaser.42 AERA further commented

that a rebuild program where the

rebuilder would be required to conduct

certification testing and be held liable

for emissions performance in-use would

be unreasonable for the many rebuilders

that are small businesses. AERA

commented that, given what is known

about the rebuilding industry, EPA has

no basis for rebuild regulations.

EPA does not believe that a major

program placing substantial new

requirements on the rebuilding industry

needs to be proposed at this time to

adequately address the Agency’s

concerns described above, based on

comments received and EPA’s findings

regarding current industry practices.

Therefore, EPA does not propose

regulations at this time under the

authority of Clean Air Act Section

202(a)(3)(D). However, EPA does believe

that establishing basic regulatory

provisions regarding engine rebuilding

under Section 203 of the Clean Air Act

(‘‘Prohibited Acts’’) would help the

rebuilding industry understand what is

needed to ensure that rebuilt 2004 and
33450 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

43Engine Switching Fact Sheet, April 2, 1991.

Docket A–95–27, II–B–6.

44 ‘‘Interim Tampering Enforcement Policy’’,

Mobile Source Enforcement Memorandum No. 1A.,

June 25, 1974. Docket A–95–27, II–B–5.

45Note that other actions not specified may also

be prohibited under Clean Air Act Section 203.

later model year engines closely

approximate original emissions

performance when they are rebuilt.

Clean Air Act Section 203(a)(3) states

that it is prohibited for ‘‘any person to

remove or render inoperative any device

or element of design installed on or in

a motor vehicle or motor vehicle

engine’’ in compliance with regulations,

either before or after its sale and

delivery to the ultimate purchaser. 42

U.S.C. 7522 (a)(3)(A). EPA commonly

refers to violations of this provision of

the Clean Air Act as tampering. Engine

rebuilding practices are currently

addressed in general terms under EPA

policies established under Clean Air Act

Section 203(a)(3) regarding tampering.

The Agency has established a policy

that when switching heavy-duty engines

the new engine must be ‘‘identical to a

certified configuration of a heavy-duty

engine of the same or newer model

year’’.43 EPA has also established

policies regarding the use of aftermarket

parts during rebuild.44

EPA is proposing to codify these

policies as they apply to rebuilding and

to propose new measures. The Agency

believes that rebuilding is currently a

time when emissions control is restored,

along with the engine itself, and that the

proposed provisions described below

will help ensure that this continues for

the 2004 and later model year engines.

Currently, the engine and all emissions

related components are treated as a

package for purposes of engine

certification and other programs and

EPA believes it is important to maintain

this view at time of engine rebuild. The

provisions proposed below would

specify what minimum action is

necessary at time of rebuild under Clean

Air Act Section 203(a)(3) to ensure

continued emissions control.45 These

provisions reflect what EPA believes

will be common practice for rebuilding

engines, but also will help to focus

attention on new emission-related

components used to meet the 2004

standards.

EPA proposes that parties involved in

the process of rebuilding or

remanufacturing engines (which may

include the removal of the engine,

rebuilding, assembly, reinstallation and

other acts associated with engine

rebuilding) must follow the provisions

described below to avoid tampering

with the engine and its emissions

controls.

(1) During engine rebuilding, parties

involved must have a reasonable

technical basis for knowing that the

rebuilt engine is equivalent, from an

emissions standpoint, to a certified

configuration (i.e., tolerances,

calibrations, specifications) of the same

or newer model year as the engine being

rebuilt. A reasonable basis would exist

if:

(a) Parts used when rebuilding an

engine, whether the part is new, used,

or rebuilt, is such that a person familiar

with the design and function of motor

vehicle engines would reasonably

believe that the part performs the same

function with respect to emissions

control as the original part, and (b) Any

parameter adjustment or design element

change is made only (i) in accordance

with the original engine manufacturer’s

instructions or (ii) where data or other

reasonable technical basis exists that

such parameter adjustment or design

element change, when performed on the

engine or similar engines, is not

expected to adversely affect in-use

emissions.

(2) A replacement engine must be of

(or rebuilt to) a configuration of the

same or later model year as the original

engine. Thus, in addition, under the

proposed regulations a party supplying

a rebuilt engine would be prohibited

from supplying a replacement engine

that is not rebuilt to a configuration of

the same or later model year as the

trade-in engine.

(3) At the time of rebuild, emissionsrelated codes or signals from on-board

monitoring systems may not be erased

or reset without diagnosing and

responding appropriately to the

diagnostic codes, regardless of whether

the systems are installed to satisfy EPA

requirements under 40 CFR 86.094–25

or for other reasons and regardless of

form or interface. Diagnostic systems

must be free of all such codes when the

rebuilt engines are returned to service.

Further, such signals may not be

rendered inoperative during the

rebuilding process.

(4) When conducting an in-frame

rebuild or the installation of a rebuilt

engine, all emissions-related

components not otherwise addressed by

the above provisions must be checked

and cleaned, repaired, or replaced

where necessary, following

manufacturer recommended practices.

EPA proposes that any person or

entity engaged in the process, in whole

or in part, of rebuilding engines who

fails to comply with the above

provisions may be liable for tampering

in violation of CAA Section 203(a)(3).

Parties would be responsible for the

activities over which they have control

and as such there may be more than one

responsible party for a single engine in

cases where different parties perform

different tasks during the engine

rebuilding process (e.g., engine rebuild,

full engine assembly, installation). EPA

is proposing no certification,

recordkeeping, or other requirements of

the rebuilder or engine owner and there

would be no in-use emissions

requirements.

Because the above proposal represents

what EPA believes would be sound

rebuilding practices for 2004 and later

model year engines, EPA does not

believe that there are costs associated

with the above proposed requirements.

Items 1 and 2 of the proposal closely

reflect established EPA policy regarding

tampering (discussed above). Any

changes to rebuild practices will be due

to the industry adjusting to the use of

new technologies. EPA believes that any

added cost to the rebuilding of the

engines will be due to the technology

used to meet the standards and not due

to the rebuilding provisions being

proposed. Additionally, EPA continues

to have the authority to regulate

rebuilding if future studies or other

information were to provide the basis

for such regulations. EPA views the

proposal above as preventative, in that

it will help ensure that the rebuild

industry is aware of the new

technologies and that rebuilding of

engines with 2004 and later technology

will not impact emissions negatively.

EPA requests comments on all aspects

of the above proposal.

To ensure that engine rebuilders and

others involved in engine rebuilding are

complying with the requirements and to

maintain a level playing field between

those who follow the rules and those

who do not, EPA’s enforcement office

intends to take action against violations

of the rebuild provisions. EPA is

concerned, however, that proving

violations will be difficult without some

form of records available for inspection.

EPA is considering the adoption of

minor recordkeeping requirements

which EPA believes would be in line

with customary business practices. The

Agency would then be able to inspect

such records to determine compliance

with the rebuild provisions. The records

would be required to be kept by persons

involved in the process of heavy-duty

engine rebuilding or remanufacturing

and would have to include the mileage

and/or hours at time of rebuild and a list

of the work performed on the engine

and related emission control systems

including a list of replacement parts

used, engine parameter adjustments,

design element changes, emissions

related codes and signals that are
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33451

responded to and reset and the response

to the signals and codes, and work

performed as described in item (4) of the

rebuild provisions above. If it is

customary practice to keep records for

groups of engines where the engines are

being rebuilt or remanufactured to an

identical configuration, such

recordkeeping practices would satisfy

these requirements. EPA would require

such records to be kept for two years

after the engine is rebuilt.

EPA’s intention with such record

keeping requirements would be to make

basic records available to the Agency

such that enforcement officials would

be able to understand what work was

performed on an engine during the

rebuild process. EPA believes that those

in the rebuilding industry already keep

detailed records on work performed on

engines as part of good business

practices and therefore, EPA believes

that the above recordkeeping

requirements would impose no

additional burden on affected

businesses. Moreover, EPA has always

had the authority to request such

records pursuant to section 208 of the

Clean Air Act and the above

requirements would only standardize

the records available for EPA

inspection. EPA requests comments on

the above record keeping requirements.

d. State Inspection/Maintenance

Programs

Many states are currently in various

stages of planning or implementing

inspection/maintenance (I/M) programs

for trucks. The programs are mostly

focused on identifying trucks with high

smoke emissions, which usually result

from tampering or poor maintenance,

and requiring their repair. EPA has

received requests from several sources

including the American Trucking

Association, the Engine Manufacturers

Association, and state organizations to

become involved in the development of

truck I/M programs, with the hope that

state programs can be standardized

under EPA guidance. Currently,

programs may differ widely from stateto-state causing a variety of problems for

the parties affected.

In response, EPA has begun an effort

in this area with the goal of developing

a guidance document that states can use

to establish programs. EPA intends to

address issues regarding testing

procedures and standards or pass/fail

cut points for heavy-duty engine I/M

programs in coordination with

interested parties. Although the

guidance document would not preclude

states from designing programs

differently, it should help decrease

program differences from state-to-state.

3. Revised Averaging, Banking, and

Trading Provisions

Today’s proposal makes changes to

the heavy-duty engine averaging,

banking and trading (ABT) provisions.

They are intended to enhance the

flexibility offered to manufacturers in

meeting the stringent standards being

proposed and to encourage the early

introduction of cleaner engines, thus

securing emissions benefits earlier than

would otherwise be the case. Further,

the proposed ABT changes also allow

EPA to propose more stringent emission

standards than it otherwise might, since

the flexibility provided by ABT lowers

the costs to manufacturers and makes it

easier to meet the technical challenges

of lower standards.

Under a modified program proposed

to be available to manufacturers

between 1998 and 2006 inclusive,

credits could be earned without the

current ABT credit discounting or

limited life provisions. These credits

could be used beginning in model year

2004 to ease the impact of the new

standards in their initial years of

applicability. With the exception of a

minor adjustment in how credit

exchanges are conducted between

families, other provisions of the existing

ABT program would remain essentially

unchanged, including prohibitions on

cross subclass and cross combustion

cycle ABT. A further description of the

proposed changes, including provisions

designed to safeguard against any

potential adverse air quality impacts, is

provided later in this section.

a. Overview of the Current Averaging,

Banking and Trading Program

The proposed changes come in the

context of the existing ABT program, the

bulk of which was adopted in 1990. The

existing program includes otto and

diesel cycle HDEs fueled by petroleum

(gasoline and diesel), gaseous fuels, and

methanol (see 55 FR 30584, July 28,

1990 and 59 FR 43472, September 21,

1994), and is available for meeting

applicable NOX and particulate matter

(PM) standards. The three aspects of

ABT: averaging, banking and trading,

are briefly described in the following

paragraphs.

Within a given manufacturer’s

product line, averaging allows

certification of one or more engine

families at levels above the applicable

emission standard (but below a set

upper limit), provided their increased

emissions are offset by those from one

or more families certified below the

same emission standard, such that the

average emissions from all the

manufacturer’s families (weighted by

horsepower and production) are at or

below the level of the emission

standard. Averaging results are

calculated for each specific model year.

The mechanism by which this is

accomplished is certification of the

engine family to a ‘‘family emission

limit’’ (FEL) set by the manufacturer,

which may be above or below the

standard (an FEL above the standard

may not exceed a prescribed upper limit

specified in the ABT regulations). Once

an engine family is certified to an FEL,

that FEL becomes the enforceable limit

used to determine compliance during

assembly line and in-use compliance

testing.

The second element of the current

ABT program is banking. Banking gives

the manufacturer generating the credits

in one model year the option to defer

their use until a later model year for

averaging or trading. Under the current

program, credits are discounted by 20

percent when banked and have a three

year life. EPA believes banking

promotes the development and early

introduction of advanced emission

control technology, which provides

emission reduction benefits to the

environment sooner than would

otherwise occur. An incentive for early

introduction arises because the banked

credits can subsequently be used by the

manufacturer to ease the compliance

burden of new, more stringent,

standards. For the same reasons,

banking can promote the introduction

and use of clean alternative-fueled

engines.

The final element of the ABT program

is trading. Since averaging is limited to

a given manufacturer’s own product

line, the manufacturer must have two or

more engine families within a given

averaging set to participate in the

program. This could limit the

opportunities for smaller HDE

manufacturers with more limited

product lines to optimize their costs.

Trading resolves this concern by

allowing credit exchanges between

manufacturers. Thus, averaging benefits

can be extended to manufacturers who

might not otherwise be able to

participate due to their limited product

lines. Trading can also be advantageous

to larger manufacturers because

extending the effective averaging set

through trading can allow for overall

optimization of cost across

manufacturers.

Due to manufacturer equity and

environmental impact concerns there

are some limitations on credit

exchanges in the existing ABT program.

First, for diesel cycle engines, NOX and

PM credit exchanges are prohibited

across the various subclasses (LHDDE,
33452 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

MHDDE, HHDDE). Second, no credit

exchanges are permitted between dieselcycle and otto-cycle engines. Finally,

cross fuel credit exchanges are

permitted only within engines of the

same basic combustion cycle and

subclass. Details on these credit

exchange restrictions, including the

reasons for their existence, are

discussed in the previously cited

Federal Register notices.

b. Description of Proposed ABT Program

Changes

As noted at the outset of this section,

EPA is proposing two principal changes

to the existing ABT program designed to

temporarily remove the discounting and

limited life of credits generated under

current provisions. Behind these

changes is the recognition that the

proposed standards represent a major

technological challenge to the industry.

ABT provisions can ease the need to

bring all engines into compliance in MY

2004 by allowing accumulated credits to

be used, for example, to temporarily

offset emissions from some particularly

difficult to control engine line. Thus,

the Agency can adopt new standards

without the need to show that they can

be met by all engines when first

implemented. While the current ABT

provisions were designed with these

same general goals in mind, EPA

believes that the nature of the challenge

presented by today’s proposed

standards justifies efforts to increase the

flexibility of the ABT program. The

Agency wishes to maximize the

flexibility and incentives for early

introduction of technology which ABT

offers. This will help insure that the

proposed new standards will, in fact, be

attainable for the manufacturers, and

will be met at the lowest cost. It is also

the case that the Agency has gained

experience with the operation of its

ABT program which gives it more

confidence in being able to successfully

modify the program in the face of this

need.

The proposal being made today would

establish a second, parallel, ABT

program targeted specifically at helping

manufacturers meet the proposed more

stringent standards in MY 2004 through

2006, the first three model years to

which the new standards would apply.

Credits could be earned under this

program beginning in 1998 and would

not be discounted, nor would they

expire after 3 years as do current ABT

credits. These credits could only be

used to comply with the 2004 standards.

If a manufacturer wished to apply them

to its compliance program for earlier

model years they could be transferred

into the original ABT program, but

would at the same time become subject

to the 20 percent discount and three

year life of the original program. EPA is

also proposing that this alternate

program would be in effect only for the

years immediately surrounding the

transition to the new standards. The

ability to generate credits under the

proposed new program would be

eliminated in 2007 (the current ABT

program would be available for 2007

and later model years). EPA thinks the

need for unlimited life and no credit

discounting to enhance the

technological feasibility of the standards

would be greatly diminished after the

first three years of the model year 2004

standards. EPA believes it is appropriate

to remove the discounting and limited

life restrictions in the modified ABT

program and still keep them in the

current ABT program because these

modifications have been considered in

developing the proposed standards, but

not prior standards subject to the ABT

program. The Agency seeks comment on

what expiration date, if any, would be

appropriate for the proposed program

modifications and why.

As in the current ABT program, only

NOX and PM credits could be earned

under the modified program. NMHC

credits would not be included because

of the potential for windfall credit

generation from the very low NMHC

levels of many current engines. NOXonly credit generation also allows the

credits to be transferred back to the

current program if deemed necessary by

the manufacturer. The NOX credits

would be applied against the NOX +

NMHC standards beginning in 2004 (but

not the NMHC cap associated with the

2.5 g/bhp-hr optional standard).

EPA proposes that the upper limits for

engine families certified above the 2004

standard and using offsetting ABT

credits would be 4.5 g/bhp-hr, NOX +

NMHC and 0.25 g/bhp-hr for PM. The

0.25 g/bhp-hr upper limit proposed here

for PM is a reduction from the 0.60 g/

bhp-hr which now applies. EPA

believes a reduction in this value is

appropriate even though the stringency

of the PM standard is not being

changed. Unless other factors dictate,

normal practice has been to set the

upper limit for FELs at the level of the

previous standard. An exception to this

practice was made in 1990 when the full

current ABT program was promulgated.

At that time engines were only meeting

a 0.60 g/bhp-hr PM standard, and it was

not clear that a 0.25 g/bhp-hr upper

limit would provide adequate flexibility

for 1994 and later model years. At that

time the PM standard was set to drop

from 0.60 g/bhp-hr to 0.25 g/bhp-hr in

1991. The 0.25 g/bhp-hr standard was to

be in place for only three model years

(1991–1993) before dropping to 0.10 g/

bhp-hr and as part of their compliance

strategy some manufacturers indicated

plans to use credits to meet the 0.25 g/

bhp-hr standard and desired that

flexibility to continue after the standard

dropped to 0.10 g/bhp-hr. By 2004, the

0.10 g/bhp-hr standard will have been

in place for ten years, and the need for

flexibility to certify above 0.25 g/bhp-hr

should have disappeared by that time.

In fact, in 1996 only three diesel engine

families out of about 90 certified above

the 0.25 g/bhp-hr level.

One of the potential problems with

ABT programs is the possibility that

manufacturers will reduce their

compliance margins relative to the

standards, or associated FELs, in order

to maximize the generation of credits for

low emitting engines and minimize the

need for credit use for high emitting

engines. Compliance margins are used

to protect against unexpected failure of

emission standards due to the

variability inherent in both producing

and emission testing of engines. To

avoid having engines exceed their FEL,

the manufacturer includes a safety

factor and certifies with emission levels

somewhat below the FEL. As the

manufacturer reduces these compliance

margins, it increases its odds of

experiencing an unexpected failure of

the FEL, either during assembly line

testing or in-use. However, the ability to

generate and use credits encourages the

manufacturer to set its FELs as low as

possible. To the extent that a

manufacturer reduces its compliance

margins under the proposed new ABT

provisions, there is a risk that such a

manufacturer’s engines would not meet

the FELs.

The Agency is unsure to what extent

such ‘‘margin shaving’’ might occur as

a result of the modified ABT program

being proposed today. However, to

protect against such a possibility, EPA

is proposing to require a minimum

margin in order to participate in the

modified ABT program. Based on

current certification data, compliance

margins vary from essentially zero to

about 18 percent, with the average being

about 10 percent. To help ensure that a

manufacturer’s engines do in fact meet

their FELs without unduly constraining

how margins are used, today’s proposal

requires a minimum margin of at least

five percent to participate in the

modified ABT program. Even though

some manufacturers have higher

margins, EPA believes that a five

percent value provides reasonable

protection against margin shaving. The

larger margins found in some engine

families may exist for other reasons. To
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33453

provide reasonable flexibility, it is also

proposed that manufacturers be

permitted to use a margin of less than

five percent if they have test data which

demonstrates that a lower margin is

sufficient. Comments are requested on

the validity of the Agency’s concern as

well as on the proposed use of a

minimum required margin. Commenters

supporting this approach should also

comment on the appropriate size of the

margin.

Since the useful life for heavy heavyduty diesels (HHDDEs) is being

proposed to increase in 2004 along with

the change in emission standards, the

question arises of how to determine

appropriate credits under the modified

ABT program for those HHDDEs engines

being certified to the shorter useful life

provisions prior to 2004. In-use

emissions generally increase, or

‘‘deteriorate,’’ with increasing mileage.

Thus, if those engines had been certified

to the longer useful life, they normally

would have had to account for more

deterioration than for the shorter life.

This would have produced a higher

FEL, and less credit, than would the

shorter life.

For NOX, dealing with the issue of the

amount of credits is fairly

straightforward. NOX emissions from

HHDDEs show little deterioration, and

in some cases can actually decline with

age. Therefore, the Agency believes an

appropriate adjustment for useful life

can be made by simply extending the

NOX deterioration factor used in

certifying the engine family to the

proposed 435,000 mile life. This should

give a conservative estimate of likely

deterioration over the longer life period.

Under this approach the extension

would be performed only for the

purposes of calculating credits for the

modified ABT program, and would not

impose added certification durability

requirements or extended recall testing

limits as the useful life (and

corresponding obligation to comply

with the emission standards) would not

be extended. If a manufacturer felt that

a projection of its deterioration factor

was inappropriate, it could exercise the

existing option under 40 CFR 86.090–

21(f) to petition the administrator for a

longer useful life for its engine, and

determine a new deterioration factor for

that new useful life.

Under the approach just described for

extending NOX deterioration factors, the

manufacturer incurs no added liability

for the mileage extension from 290,000

miles to 435,000 miles. The above

approach seems appropriate to the

Agency for purposes of quantifying the

amount of credits given the transitional

nature of the useful life issue and the

general stability and predictability of

NOX emissions. However, in various

credit and trading programs EPA has set

policy that credit generation should be

based on an enforceable obligation to

achieve the expected emission

reductions. See, e.g., Interim Guidelines

on the Generation of Mobile Source

Emission Reduction Credits, 58 FR

11134 (February 23, 1993). If deemed

appropriate, this could be accomplished

by requiring the manufacturer to certify

using the same extended NOX

deterioration factor it used for credit

calculations. This would establish inuse liability for the extended mileage

period. If this were done, it would apply

only for the NOX standard. EPA believes

this extended useful life could be

accomplished without imposing

additional certification burdens or

requirements, given the current

flexibility in certification regulations

and the expected deterioration

associated with NOX emissions over

time. EPA invites comments on this

alternate approach as well as the

proposal to calculate the amount of NOX

credits without extending the useful

life. Comments should address which of

these approaches should be adopted in

the final rule.

In the case of particulate matter (PM)

emissions, the Agency has much less

confidence in the reliability of

projections from the current 290,000

mile life. In this case there is a greater

possibility of unexpected changes in

emissions later in the engine life which

would not be consistently captured with

such an approach. Therefore, EPA is

proposing to allow credits to be

generated only for the applicable engine

family’s certified useful life period. In

most cases this would be 290,000 miles.

However, as with NOX, if a

manufacturer wished to generate credits

for a longer period, it could petition the

Administrator under the provisions of

40 CFR 86.090–21(f) for a longer useful

life for its engine. It would then be able

to generate credits for that entire useful

life period.

Finally, it should be noted that EPA

is proposing to revise the technique

used to calculate credit exchange

(generation and use) amounts. In the

current ABT system, credits are

generated based on the lowest

horsepower configuration in a family

and credit use is calculated based on the

highest horsepower configuration.

Credit generation is calculated based on

the configuration which generates the

least benefit within the family while

credit use is based on the configuration

which requires the most credits to

comply. In some cases this can result in

large offsets (i.e., credits are generated at

the lowest rate and credits required at

the highest rate). Based on EPA’s

experience with ABT programs, we find

this offset to be unnecessary. Over the

past five years the ABT program has

been implemented smoothly, leaving

less need for the safeguards this

provision brought to the original

program. Furthermore, this provision

tends to introduce a penalty for credit

generating engines, thus reducing the

incentive to introduce clean technology.

Therefore, EPA proposes to base such

calculations on sales-weighted average

horsepower values within each family.

EPA believes use of an average

horsepower for generating and using

engines is sufficient to ensure no

environmental loss from the credit

transaction.

EPA received comments on the

ANPRM requesting clarification on

whether or not, and if so, how credits

from engines certified below the

applicable standard can be used by

entities other than the engine

manufacturers (e.g., engine purchasers).

EPA believes that in some

circumstances this could well be

appropriate and consistent with the

intent of the ABT regulations. EPA asks

comment on what revisions or

clarifications may be needed to the ABT

program to facilitate this possibility. For

example, EPA is interested in comment

on how we can assure that credits not

be counted by both the engine

manufacturer and the vehicle/engine

user (double counted).

The interim modifications to relax the

credit discounting and lifetime

restrictions for model years 1998–2006

are being included primarily to assist in

compliance with the proposed

standards beginning in 2004. As was

discussed earlier in this section, the

technological challenge of meeting the

proposed standards is much less for

otto-cycle engines as compared to diesel

cycle engines. In fact many models

already have certification levels near or

below the level of the proposed

standard. While the revised ABT

program could provide an incentive to

produce even cleaner otto-cycle engines

before 2004, EPA is concerned that the

discount and lifetime revisions would

provide ‘‘windfall credits’’ to the ottocycle industry. A similar concern does

not exist for diesel cycle engines,

because their current NMHC+NOX

emission rates are well above the level

of the proposed standard. EPA asks

comment on this issue including

whether or not and why these two

program changes should be extended to

otto-cycle engines or just the current A,

B,& T program should be available.
33454 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

46Memo from Tad Wysor (EPA) to Air Docket A–

95–27, ‘‘Summary of Heavy-Duty Engine Emission

Control Technologies,’’ II–B–4, August 24, 1995.

47The technological feasibility of meeting the

proposed standards using alternative fuels is

discussed in Chapter 4 of the RIA.

In its comments on the ANPRM

submitted on behalf of a consortium of

environmental groups, NRDC raised

several objections to the possible ABT

program changes discussed in that

document and in the SOP. Among these,

NRDC opposed removal of the

discounting and limited life provisions

of the current program. NRDC argued

that these changes could lead to

unnecessary delays in compliance with

the proposed new standards and could

result in increased emissions.

Commenting specifically on the removal

of discounting, NRDC argued that in the

absence of discounting, the public

‘‘relinquishes all of the benefits of

unanticipated advances in technology.’’

The Agency does not agree with these

comments. As described above,

existence of the ABT program allows the

Agency to propose and finalize a

standard that might not be otherwise

appropriate under the CAA, since ABT

reduces the cost and improves the

technological feasibility of achieving the

standard. Furthermore, the generation of

credits means that emission reductions

have been realized earlier than required

by the standards, which EPA believes is

a benefit to the public. The fact that the

use of credits would allow some specific

engine families to delay compliance

with the proposed new standards has no

inherent air quality impact since the

credits represent offsetting emission

reductions below the applicable

standard from other engines. EPA

encourages further comment on the

appropriateness of the Agency’s

proposal to impose no discount or life

limit on credits generated and used

under the modified ABT program.

In their comments NRDC also

opposed expansion of the trading

provisions to include cross-cycle, cross

sub-class or cross-source trading. None

of those changes are included in today’s

proposal. Comments are invited on the

appropriateness of EPA at some later

date proposing to allow cross-cycle,

cross-cycle with the same fuel, crosssubclass or cross-category (e.g., highway

and non-road) credit exchanges as part

of the modified ABT program.

In their comments on the ANPRM,

NRDC stated that only engines meeting

the proposed standards early should be

able to get the benefits of the temporary

changes to discount and lifetime

provisions. EPA explored this concept,

but for two reasons chose not to include

it in the NPRM. First, such a restriction

would reduce the value of ABT

programs in assisting transition to the

2004 standards. A manufacturer would

have no incentive to introduce

improved technology early unless the

engine made it all the way to the level

of the proposed standards. Second,

since early additional emission

reductions have equal value whether the

engine is above or below the proposed

standards it would be inconsistent with

air quality goals to create a disincentive

for early additional emission reductions.

However, this view is premised on the

design criterion discussed above, i.e., no

cross-cycle credit exchanges. If crosscycle exchanges are permitted without

some form of a trigger level for

eligibility, an unusual situation could be

created where gasoline-fueled otto cycle

engines could generate credits for use by

petroleum-fueled diesel cycle engines.

This in turn would create a disincentive

for technology innovation for diesels

which is one of the key goals for the

ABT program.

Readers are encouraged to review the

draft regulations for a fuller

understanding of how the proposed

ABT program would operate. The

Agency solicits comments on all aspects

of the ABT changes being proposed,

including comments on the benefit of

these changes to manufacturers in

meeting the proposed emission

standards and any potential air quality

impacts which might be associated with

them.

IV. Technological Feasibility

This section discusses the emission

control technologies that EPA believes

would be available for engine

manufacturers to meet the proposed

2004 standards. Included in this

discussion are estimates of emission

reductions associated with these

technologies and their potential to

impact performance. Because of the

significant differences between the

operation, emissions, and likely control

strategies for diesel and gasoline heavyduty engines, each engine type will be

treated separately. Further information

on the basic characteristics of diesel and

gasoline heavy-duty engines may be

found in Docket A–95–27.46

Following is a summary of the key

technologies discussed in the

Regulatory Impact Analysis (RIA). For

more detail on the emission control

technology described in this section, see

Chapter 4 of the RIA. This chapter of the

RIA also describes many of the

technologies that are still under

development that could allow heavyduty highway engines to meet or exceed

the reduced emission standards

proposed in this action. Several

technologies described in the RIA are

not included in this section because

EPA believes they are less likely to be

used by engine manufacturers in 2004

than those strategies, techniques, and

technologies described here.47

The following discussion of

technologies includes a wide range of

alternatives from which manufacturers

may choose to comply with the

proposed emission standards. Not all of

these technologies will be needed to

reduce NOX or HC emissions to comply

with the proposed emission standards.

Manufacturers may develop and use

technologies to improve fuel economy

or performance or to control particulate

emissions at a lower cost. The analysis

of economic impacts in Section V.B.

reflects this by assessing the

incremental cost of adopting a limited

package of technological changes to

heavy-duty engines.

As will be discussed further below,

EPA believes that the goals set by this

proposal are challenging but feasible.

They clearly represent major reductions

compared to current engine emission

levels. At the same time, heavy-duty

engine technology is in a period of rapid

development, and EPA does not see any

reason to expect that such development

will be slowed in the foreseeable future.

Published work shows that research

engines are already beginning to

approach the levels required by the new

standards. There are certainly many

significant technical challenges to

translating research work into

acceptable products for the marketplace.

However, the emission targets are set in

the framework of a long lead time,

substantially longer than has been the

case in many previous heavy-duty

engine rules. Also, except for the use of

EGR on heavy-duty diesel engines, each

of the technologies anticipated for

complying with the proposed emission

standards, as described below, have

already been applied to and proven on

recent model year heavy-duty engines.

Thus, on balance, the Agency believes

that the proposed standards are feasible

for the heavy-duty industry.

Through comments on the ANPRM,

some concern has been expressed to

EPA that lower standards may be more

appropriate for heavy-duty engines. One

suggestion was that heavy-duty diesel

engines should be required to meet a

0.05 g/bhp-hr PM standard since urban

buses are now held to this level. In

addition, commenters recommended

that separate, lower HC plus NOX and

CO standards should be set into place

for heavy-duty gasoline engines. Based

on the information discussed further
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33455

below and in the RIA, EPA believes that

the proposed standards represent the

lowest levels consistent with the

constraints of section 202 (a)(3)(A)(i) of

the Clean Air Act. That section requires

EPA to establish the ‘‘greatest degree of

emission reduction achievable through

the application of technology which the

Administrator determines will be

available for the model year to which

such standards apply, giving

appropriate consideration to cost,

energy, and safety factors associated

with the application of such

technology.’’

Given the uncertainty associated with

the long lead time, this analysis would

be re-evaluated in the proposed 1999

review of the feasibility of the standards

discussed in section III.B above. EPA

requests comment on the availability

and effectiveness of emission control

technologies that may be applied to

heavy-duty on-highway engines to meet

the proposed standards. EPA also

requests specific comment on the

appropriateness of a separate, lower

standard for heavy-duty gasoline

engines.

A. Diesel Engines

Highway heavy-duty diesel engine

manufacturers have historically been

very successful in lowering both NOX

and PM levels to meet EPA emission

standards. EPA standards have required

a reduction in NOX emissions of over 50

percent and PM reduction of over 80

percent largely within the past 5 years.

Engine manufacturers have been able to

achieve the majority of these reductions

using changes in engine hardware with

minimal reliance on exhaust

aftertreatment devices. Today’s heavyduty diesel engines are also well below

the standards for HC and CO. Over this

same period, engine manufacturers have

been able to provide their customers

with increased power, improved fuel

economy and improved engine

durability.

Indications are that HC, NOX and PM

control technologies have not yet

reached their full potential. A broad

range of current published research,

referenced in the RIA, shows that HC +

NOX levels of 2.5 g/bhp-hr with a PM

level of 0.10 are already being

approached in laboratory diesel engines.

One example, discussed in the RIA, is

a turbocharged and aftercooled engine

that uses optimized swirl and cooled

EGR to achieve emission levels of 2.0 g/

bhp-hr HC + NOX and 0.13 g/bhp-hr PM

(average of three operating modes).

Engine manufacturers and other

companies have conducted extensive

research that is still confidential or is

not yet published for other reasons. EPA

believes that the unpublished work in

the field of diesel engine emission

control represents progress in research

and development that goes well beyond

that described in the published

literature. The Agency recognizes that

such results do not, of themselves,

demonstrate the feasibility of reaching

such levels in production engines.

However, as discussed below, EPA

believes that for the 2004 time frame,

technologies will be optimized to

meet—and in some cases possibly

exceed—future emission-control targets.

Under the proposal, the engine

manufacturers will have an effective

leadtime of eight years. This is twice

that available in previous heavy-duty

engine rules. This long leadtime is

valuable to heavy-duty diesel engine

manufacturers for several reasons. Due

to the stringency of the proposed

standards, it is likely that manufacturers

will need to make fundamental changes

in engine technology. History has

shown that emissions can be reduced

more cost-effectively when the engine

manufacturers are given a reasonable

amount of time for research and

development (R&D). The relatively long

lead time available for this rule provides

adequate time for a strong, orderly, and

comprehensive R&D program which

focuses not only on emission reduction,

but also on addressing fuel

consumption, durability and

maintenance concerns. EPA anticipates

that heavy-duty diesel engine

manufacturers would focus primarily on

NOX control strategies to meet the

proposed 2004 standards rather than

NMHC control. EPA also expects that

manufacturers will focus on in-cylinder

control strategies as opposed to

aftertreatment approaches. Combustion

optimization through improved air and

fuel controls are expected to be at the

center of the strategy for reducing NOX

emissions (and HC where possible),

while holding the line on PM emission

rates. Such strategies also hold promise

for positive impacts on fuel

consumption. Combustion optimization

can be achieved through a combination

of strategies related to combustion

chamber design improvements,

upgrades in fuel system controls, and

modifications of intake air distribution

approaches and characteristics. The

R&D associated with the assessment and

optimization of such strategies and the

application of the results of this work to

the various heavy-duty diesel engine

models will need to be conducted

during the available leadtime.

Individual technologies may have

different effects on NOX, PM, and HC

emissions, though manufacturers can

balance these to produce an engine that

effectively controls all emissions. NOX

emissions are controlled primarily by

lowering peak combustion chamber

temperatures. However, simply

lowering combustion temperatures can

lead to an increase in PM or HC

formation because PM and HC are more

likely to form at lower temperatures.

NOX control strategies such as retarding

fuel injection timing by themselves are

limited because they cause an increase

in PM or HC. Engine manufacturers

have had to devise more sophisticated

emission control strategies that allow

them to simultaneously control NOX,

and PM, and HC. Manufacturers have

used a variety of technologies, often

balancing their effects and optimizing

among them to comply with the

emission standards. EPA therefore

believes that manufacturers will need

some, but certainly not all, of the

technologies that are primarily for

controlling PM or HC emissions to meet

the standards proposed in this action.

Combustion chamber design is a key

area for improvements to reduce

emissions and increase performance.

Manufacturers are continuously

working to improve the combustion

chamber geometries of their engines to

maximize efficiency and reduce

emissions. Design variables include

such things as the shape of the

combustion chamber, the location of the

fuel injector, valve timing, and air

intake geometry. Efforts to redesign the

shape of the combustion chamber and

the location of the fuel injector have

been directed primarily at optimizing

the relative motion of the air and

injected fuel. Increasing the turbulence

of the intake air (such as through

inducing swirl) can reduce NOX and PM

emissions from diesel engines by

improving the mixing of air and fuel in

the combustion chamber. Increasing the

compression ratio of the engine will

generally reduce fuel consumption and

PM, but tends to increase NOX

emissions. Moving from 2 to 4 valves

per cylinder can be used to improve

engine breathing and will allow the fuel

injector to be placed in the center of the

cylinder bore, improving combustion.

Finally, higher precision in the bore

honing and the matching of the piston

and rings can reduce the amount of oil

that passes from the crankcase into the

cylinder. This will result in a reduction

in PM.

Emission control and diesel engine

performance may also be improved

through advances in fuel injector

design. Design variables for fuel

injectors include injection pressure,

spray pattern, and control of the rate of

fuel injection over the course of the

injection event. The combination of
33456 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

reduced droplet size and improved

mixing leads to decreased HC and PM.

This improved fuel injection can

simultaneously lower NOX emissions by

reducing the time between the initial

injection and ensuing ignition of the

fuel, which minimizes the level of

premixed combustion.

Varying the rate at which fuel is

injected into the cylinder is another

strategy that may be used to reduce HC,

NOX, and PM emissions. This ‘‘rate

shaping’’ is especially effective when

combined with electronic controls. A

low rate pilot injection may be used at

the beginning of combustion to shorten

the ignition delay, therefore shortening

the pre-mixed burning phase of

combustion, which is most conducive to

NOX formation. At low loads, improved

fuel injection can reduce NOX, the

soluble organic fraction of PM, and fuel

consumption, with some possible

penalty in smoke. One experimental

study, referenced in the RIA, showed

that rate shaping and fuel injection

parameters could be used to achieve 3.5

g/bhp-hr NOX and 0.10 g/bhp-hr PM

from a diesel engine operating at 75

percent load, without the use of EGR

(HC levels were not reported).

Engine manufacturers may reduce

emissions from their engines through

optimization of charge air pressures and

response rates for all types of engine

operation (speed and load). Charge air

compression is used in almost all

current heavy-duty diesel engines. For

four-stroke diesels, turbocharging is the

most common method of increasing

boost air pressure into the cylinder.

With an increase of air moved into the

cylinder, more fuel may be injected

resulting in higher power. One

limitation of a turbocharger is that it has

an inertial lag time associated with its

response to changing operating

conditions. As a result, during transient

operation, too little intake air

compression may occur at the beginning

of an acceleration, while an excessive

boost may remain at the start of the next

steady-state operation. In addition, a

given turbocharger optimized for high

loads may have compromised efficiency

at low loads. A variable geometry

turbocharger may be used to increase

the boost response rate and provide

appropriate air/fuel ratios for varying

loads and speeds. This control of the

air/fuel ratio can often lead to decreased

emissions. In one study, referenced in

the RIA, electronic controls combined

with a variable geometry turbocharger

achieved a 37 percent reduction in HC

and a 34 percent reduction in NOX

without an increase in PM over a

portion of the HD-FTP.

Exhaust gas recirculation (EGR) is

probably the most important in-cylinder

diesel engine control technology for

obtaining significant NOX reductions to

meet the 2004 proposed standard.

Under this approach, a portion of the

exhaust gas is routed back into the

intake manifold. This has the effect of

reducing peak temperatures, and thus

reducing NOX formation in the cylinder.

This strategy will be focused on low and

medium load conditions due to possible

PM and fuel consumption increases at

high loads. EPA expects that the

effectiveness of the EGR system will be

optimized and its potential adverse

affects minimized by integrating its

control into the overall electronic

controls used for other engine systems.

One method for controlling the PM

emissions attributed to EGR, which may

be used on some designs, is to cool the

exhaust gas recirculated to the intake

manifold. By cooling the recirculated

gas, more exhaust gas can be added to

the intake charge without reducing the

supply of fresh air into the cylinder.

Another concern associated with EGR is

that, by being recirculated, the

particulate or other contaminants in the

exhaust may find its way into the oil

and degrade the oil’s performance,

resulting in a durability concern. This

durability concern may be alleviated by

keeping the EGR fraction of the intake

charge below 10 or 15 percent,

modifying lubricating oil additive

packages, improving oil filtration, and/

or more frequent oil changes. In the

worst case, some manufacturers may

consider some form of an in-line

particulate removal device such as a

filter in the stream of recirculated

exhaust gas.

Engine manufacturers have started to

use oxidation catalysts in some cases

where engines have needed help

meeting particulate standards. Efforts

are also being made to develop a

durable and cost effective NOX

reduction catalyst that will operate on

the lean exhaust which is produced by

diesel engines. However, due to

projected engine design improvements,

EPA expects the engine manufacturers

to focus on meeting the proposed

standard without the use of

aftertreatment. Alternatives to

aftertreatment are generally preferable

because of high costs, space

requirements, backpressure effects, and

possible durability concerns (with

respect to long life of diesel engines)

associated with aftertreatment devices.

In summary, EPA believes that

combustion optimization through

strategies such as air and fuel control

and EGR would be the primary NOX

control strategy for meeting the

proposed standards. However, as NOX

emissions are reduced through engine

controls, there is often a tradeoff

resulting in an increase in PM

emissions. Strategies that would be

expected to be used to control PM

emissions include further optimization

of combustion chamber geometry,

advances in fuel injection, fuel rate

shaping, and advances in turbocharger

design. These PM control technologies

may also be used to increase power from

the engine and reduce fuel

consumption. EPA believes that

manufacturers would make use of the

PM control technologies, regardless of

further emission control, to achieve

benefits in power and fuel consumption.

All of the technologies described in this

section have been applied to and proven

in on-highway diesel engine

applications. Further, all of the

technologies, with the exception of EGR,

have been proven in heavy-duty diesel

applications. Even EGR is used on at

least one 1996 light heavy-duty diesel

engine model. By combining these

strategies in various ways, EPA believes

it is technologically feasible to meet the

proposed standards for model year

2004. Together these strategies should

allow heavy-duty diesel engines to

achieve the proposed NOX + NMHC

reductions without increasing PM or

other emissions.

Most of the results discussed above

are based on research using

conventional on-highway diesel fuel.

Another parameter which affects

emissions from diesel engines is the

composition of the fuel being used.

While much can be said about the effect

of current fuels on current engines, the

degree of sensitivity of future, low

emitting, engines to fuel parameters is

not as well understood. The Agency’s

current view is that fuel changes could

reduce the amount of emission control

necessary for the engine, but fuel

changes are probably not necessary to

meet the proposed standards. However,

this remains an area of uncertainty and

is one of the issues which would be

addressed further in the proposed 1999

review of the feasibility of the standard,

as discussed in section III.B above.

B. Gasoline Engines

Gasoline engine manufacturers are

producing heavy-duty engines that

exceed the level of emission control

required by current standards. Some

1996 model year heavy-duty gasoline

engine families have certified emission

levels below the standards proposed for

2004. Thus, the Agency believes that

complying with the proposed standards

will be fairly straightforward for

gasoline engines. EPA requests
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33457

48 42 U.S.C. 7521(a)(3)(A)(i).

comment on the appropriateness and

effectiveness of the technologies

described below.

Current heavy-duty gasoline engine

emission levels are achieved mainly

through the use of EGR and either airassisted oxidation catalysts or three-way

catalysts. Many of these engines have

used open-loop engine controls and

electronic fuel injection for years.

However, the three-way catalysts

require precise control of the exhaust

air-fuel ratio for maximum performance.

By including a feedback loop in the

control system, the precision of the airfuel ratio in the exhaust is greatly

increased, especially during transient

operation. Therefore, EPA believes that,

through the use of closed-loop

electronic control and the upgrades to

system management available with that

approach, manufacturers can

significantly improve their emissioncontrol capability. These reductions

may be further assisted by

improvements in fuel injection

technology or EGR.

Improving fuel injection has been

proven to be an effective and durable

strategy for controlling emissions and

reducing fuel consumption from

gasoline engines. Improved fuel

injection will result in better fuel

atomization and a more homogeneous

charge with less cylinder-to-cylinder

and cycle-to-cycle variation of the airfuel ratio. These engine performance

benefits will increase as technology

advances allow fuel to be injected with

better atomization. Increased

atomization of fuel promotes more rapid

evaporation by increasing the surface

area to mass ratio of the injected fuel.

This results in a more homogeneous

charge to the combustion chamber and

more complete combustion. EPA

believes that multi-port fuel injection

will be used in most, if not all,

applications under the proposed

standards because of its proven

effectiveness. Because of the

performance and fuel consumption

improvements associated with multiport fuel injection, it is likely that most

engine models would incorporate this

technology by 2004 anyway.

Exhaust gas recirculation is currently

used on heavy-duty gasoline engines as

a NOX control strategy. Recirculated

gases reduce the peak flame

temperature, thus reducing NOX.

Because the recirculated gases limit the

amount of oxygen available for

combustion, there can be some penalty

in fuel economy if too much gas is

recirculated. One method of increasing

the engine’s tolerance for EGR is to

stratify the recirculated gases in the

cylinder. This stratification allows high

amounts of dilution near the spark plug

for NOX reduction while making

undiluted air available to the crevices,

oil films, and deposit areas so that HC

emissions may be reduced. Stratification

may be induced radially or laterally

through control of air and mixture

motion determined by the geometry of

the inlet ports. One study of this

strategy is referenced in the RIA.

EPA believes that the most promising

overall emission control strategy for

heavy-duty gasoline engines is the

combination of a three-way catalyst and

closed loop electronic control of the airfuel ratio. Control of the air-fuel ratio is

important because the three-way

catalyst is only effective if the air-fuel

ratio is at a narrow band near

stoichiometry. For example, for an 80

percent conversion efficiency of HC,

CO, and NOX with a typical three-way

catalyst, the air-fuel ratio must be

maintained within a fraction of one

percent of stoichiometry. During

transient operation, this minimal

variation cannot be maintained with

open-loop control. For closed-loop

control, the air-fuel ratio in the exhaust

is measured by an oxygen sensor and

used in a feedback loop. The throttle

position, fuel injection, and spark

timing can then be adjusted for given

operating conditions to result in the

proper air-fuel ratio in the exhaust. In

addition, electronic control can be used

to adjust the air-fuel ratio and spark

timing to adapt to lower engine

temperatures, therefore controlling HC

emissions during cold start operation.

A three-way catalyst may be a single

converter or have two converters in

series. A converter is constructed of a

substrate, washcoat, and catalytic

material. The substrate may be metallic

or ceramic with a flow-through design

similar to a honeycomb. A high surface

area coating, or washcoat, is used to

provide a suitable surface for the

catalytic material. Under high

temperatures, the catalytic material will

increase the rate of chemical reaction of

the exhaust gas constituents. In a typical

three-way catalyst design with two

converters, the first converter will be a

reduction catalyst which converts NOX

to nitrogen and water. Palladium is

often used as the NOX reduction

catalytic material with rhodium added

to control ammonia formation.

Ammonia, which may be converted

back to NOX in the second converter,

can also be controlled through the use

of tight air-fuel ratio control. The second

converter is an oxidation catalyst and

typically uses platinum and rhodium to

convert HC and CO to CO2 and water.

Three-way catalytic converters using a

single monolith generally use one or

more of the metals mentioned above

(platinum, rhodium, and palladium) to

catalyze the desired reactions. These

designs may be preferable since less

materials are used and less space is

required.

In summary, EPA believes that

gasoline engine manufacturers, to the

extent they need to make improvements,

can meet the proposed standards by

refining those technologies already

employed on their engines. The use of

more powerful electronics to better

control combustion and aftertreatment

will likely be the most important focus

of technology upgrades enabling

manufacturers to reduce emissions. EPA

therefore believes it is technologically

feasible for heavy-duty gasoline engines

to meet the proposed standards for

model year 2004.

C. Safety and Energy

One of the factors considered by EPA

in assessing the feasibility of its

proposed standards is safety. Section

202(a)(3) of the Clean Air Act requires

that EPA set emission standards for

heavy-duty engines that reflect the

‘‘greatest degree of emission reduction

achievable through the application of

technology which the Administrator

determines will be available for the

model year to which such standards

apply, giving appropriate consideration

to cost, energy, and safety factors

associated with the application of such

technology.’’ 48 EPA has considered the

safety implications of the standards in

today’s proposal. In the course of this

consideration, the Agency has consulted

with the Department of Transportation,

to make use of that Department’s

expertise in assessing vehicle safety.

EPA does not believe that there are

any significant safety concerns

associated with the technologies

described in this section. In general,

they all represent the progressive

development of technology already in

use. Except for the use of EGR on heavyduty diesel engines, all of the

technologies anticipated for use in 2004

have already been applied to and

proven on recent model year heavy-duty

engines. As for the use of EGR, EPA is

not aware of any safety problems where

EGR has been used on light-duty diesel

vehicles or on heavy-duty gasoline

engines. EPA sees no reason why the

use of EGR on heavy-duty diesels would

create any new safety problems. EPA

welcomes comment on any safety issues

that commenters believe might be

associated with today’s proposal.

EPA believes that there will not be

significant energy concerns associated
33458 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

with the control strategies which would

be available to meet the proposed

standards. EPA expects that

manufacturers will focus on

maintaining or decreasing the fuel

consumption of their engines in the

development of engines that will meet

the proposed standards. For heavy-duty

diesel engines, many of the technologies

that would likely be used to control PM

emissions would also be used to offset

the negative effects of EGR on fuel

economy. For heavy-duty gasoline

engines, the combination of fuel

injection advances and closed-loop

control used to control emissions could

actually result in a fuel economy

benefit.

V. Impacts of Proposed Program

A. Environmental Impacts

1. Heavy-Duty NOX Emissions Impacts

The NOX inventories used for this

rulemaking were based on a detailed

analysis of NOX emissions that was

prepared for EPA by E.H. Pechan and

Associates, as described in Section II.

To calculate the impact of this proposal,

it is necessary to estimate average NOX

and average NMHC emission levels

resulting from the combined

NOX + NMHC standard. The NOX

emission level was determined by

analyzing the relative cost effectiveness

of NOX and NMHC emissions reduction

technologies; NOX-reduction

technologies are expected to be much

more cost-effective than NMHCreduction technologies, which are only

practical for a small number of engine

families that have relatively high NMHC

emissions. As a result, NMHC emissions

are expected to be only slightly less than

current levels, (see following section for

additional discussion), and NOX

emissions are expected to be reduced to

below 2.0 g/BHP-hr to provide a

sufficient compliance margin. Thus, the

effect of the combined standards on

NOX was modeled as being equivalent

to a 2.0 g/BHP-hr NOX-only standard.

Full details of the air quality impacts

can be found in the RIA. The following

paragraphs summarize the key results.

The public is encouraged to read the full

analysis, and to comment on all aspects

of the work.

Figure 7 shows projections of total

NOX emissions, with and without the

proposed controls, for the entire nation.

The emissions are projected to decline

over the next several years, due to the

implementation of previously

promulgated controls, but then begin to

increase due to growth in the number of

vehicles and other sources. By the year

2020, without additional control, total

national NOX emissions are projected to

actually exceed current levels. Even

with the implementation of the

proposed standards, total NOX

emissions are expected to grow in the

future. Figure 8, which presents the

projections of NOX emissions from

heavy-duty engines, with and without

the proposed controls, shows that the

proposed standards are expected to

prevent the contribution of heavy-duty

engines from increasing before the year

2020.

BILLING CODE 6560–50–P
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33459
33460 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

BILLING CODE 6560–50–C
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33461

49These regions include all counties in ozone

nonattainment, as well as all counties in attainment

in: California, Texas, all states east of the

Mississippi River, and all states on the western

border of the Mississippi River.

50 ‘‘Conversion Factors for Secondary Formation

of PM Nitrate from NOX Emissions for California’’,

Draft, June 6, 1996, Leon J. Dolislager, Nehzat

Motallebi, Bart E. Croes, California Air Resources

Board.

The estimates of the total NOX

reductions are shown in Table 3. Almost

half of the reductions would occur in

nonattainment areas, and nearly 90

percent of the reductions would occur

in regions where NOX emissions are

reasonably expected to have a

significant effect on nonattainment

areas.49

TABLE 3.—ESTIMATED NATIONAL NOX

Emissions Reductions From Proposed Standards for Heavy-Duty

Engines

[Thousand Tons per Year]

Year

Diesel

emissions

reductions

Gasoline

emissions

reductions

Total

emissions

reductions

2005 ...... 106 12 118

2010 ...... 518 59 577

2015 ...... 832 102 934

2020 ...... 1,066 149 1,215

2. Heavy-Duty NMHC Emissions

Impacts

Estimates of the impact of this action

on NMHC emissions were developed by

assuming that the combined NMHC plus

NOX standards are equivalent to that of

0.4 g/BHP-hr NMHC-only standards;

this discussion briefly summarizes the

detailed analysis in the RIA. This is

consistent with the previous assumption

that the combined standards are

equivalent to that of 2.0 g/BHP-hr NOXonly standards It was also assumed that,

without the proposed NMHC control,

average NMHC emissions from 2004 and

later model year heavy-duty engines

would be the same as 1994 model year

heavy-duty engines (based on

certification data), since there are no

new PM or HC standards after 1994.

Using these assumptions, the expected

exhaust NMHC reductions for 2004 and

later model year engines would be 9

percent for diesels and 24 percent for

gasoline. The effect of these reductions

on nationwide emissions was modeled

using MOBILE5a, using the VMT

estimates from Pechan. The results are

shown in Table 4. The reason why these

reductions are small relative to the

decrease in the numerical level of the

standards is that many heavy-duty

engines are currently being certified

well below their applicable hydrocarbon

standards. As is discussed in the RIA,

however, the lowering of the NOX

standard in 1998 may cause some

increases in NMHC emissions from

diesel engines (even if the emissions

remained below the current HC

standard), such that the actual benefit of

this standard may be greater. Moreover,

it is worth noting that the inclusion of

NMHC emissions in the proposed

standards also serves to prevent

increases in NMHC emissions that may

otherwise have occurred as a result of

lowering the NOX standard, given the

tradeoff between NOX reductions and

HC/PM reductions that is often observed

with diesel engines.

TABLE 4.—ESTIMATED NATIONAL

NMHC EMISSIONS REDUCTIONS

FROM PROPOSED STANDARDS FOR

HEAVY-DUTY ENGINES

[Thousand Tons per Year]

Year

Diesel

emissions

reductions

Gasoline

emissions

reductions

Total

emissions

reductions

2005 ...... 2.2 0.5 2.7

2010 ...... 6.8 2.9 9.7

2015 ...... 12.1 5.2 17.3

2020 ...... 16.4 8.4 24.8

3. Particulate Emissions Impacts

The action being proposed should not

have any effect on direct particulate

emissions from heavy-duty engines,

since it does not change the particulate

standard. Manufacturers are expected to

continue to produce engines with

particulate levels slightly below the

standard. The NOX reductions discussed

above, however, are expected to reduce

the concentrations of secondary nitrate

particulates. As discussed previously,

NOX can react with ammonia in the

atmosphere to form ammonium nitrate

particulates. In some areas in the

western states, ammonium nitrate

particulates can represent more than

one quarter of the fine particulate in the

air. The California Air Resources Board

has preliminarily estimated that, in

California, there are typically 4 to 19

(with an average of about 7) tons of

nitrate particulate in the air for every

100 tons of NOX in the air.50

Unfortunately, such information is not

available for the rest of the nation. As

was described in the RIA, the national

average for the years of interest was

estimated as 4.3:100, assuming that the

ratio would be 7.0 for the western part

of the nation, and 3.5 for the eastern

part. This estimate was used to

determine the equivalent fine

particulate emissions reductions caused

by the NOX emissions reductions, as is

shown in Table 5. Future year estimates

are extrapolations based on the NOX

reduction estimates for those years. The

Agency recognizes the limited precision

of these estimates, and requests

comments on the potential for

developing better estimates of the

expected relationship between NOX

emissions and nitrate particulate

formation during and after the year

2004.

TABLE 5.—ESTIMATED EQUIVALENT

NATIONAL PARTICULATE EMISSIONS

REDUCTIONS FROM PROPOSED

STANDARDS FOR HEAVY-DUTY ENGINES

[Thousand Tons per Year]

Year

Total

NOX

emissions

reductions

Equivalent particulate

emissions

reductions

2005 .......................... 118 5

2010 .......................... 577 25

2015 .......................... 934 40

2020 .......................... 1215 52

4. Effect on Ozone

The effect of these NOX emissions

reductions on ozone concentrations is

expected to vary geographically. In

general, when fully phased-in, the effect

of this action in most nonattainment

areas should be a reduction in ozone

concentrations on the order of a few

percent. It should be noted, however,

that the potential exists for a few

localized areas to actually experience

slight increases in ozone concentrations

as a result of NOX emissions reductions.

The Agency is attempting to develop a

more precise analysis of the effect of

these reductions on ozone, including an

analysis of the extent to which potential

localized ozone increases could be

mitigated through other emissions

control programs.

5. Other Effects

Reducing NOX emissions has a

positive effect on visibility, since both

NO2 and nitrate particulates absorb

visible light. As noted in the RIA, NO2

and nitrate particulates can be

responsible for 20 to 40 percent of the

visible haze in some urban areas. The

effect of this action on visibility should

be small but potentially significant,

given that it is expected to reduce

overall NOX emissions by several

percent. For example, the proposed

controls are expected to result in about

5 percent less total NOX in the year

2020, and therefore would be expected
33462 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

to result in a decrease in haze of about

1 percent in an area where NO2 and

nitrate particulates cause 20 percent of

the haze. NO2 and nitrate particulates

also contribute to decreased visibility in

scenic rural areas in southern California,

so these areas would similarly benefit

from reduced NOX emissions.

The standards being proposed here

are also expected to provide benefits

with respect to nitrogen deposition. The

1.2 million-ton per year reduction in

NOX emissions expected in 2020 as a

result of this action is greater than the

400,000-ton per year reduction expected

from Phase I of the Agency’s acid rain

NOX control rule (59 FR 13538), which

was considered to be a significant step

toward controlling the ecological

damage caused by acid deposition. This

action should also lead to a reduction in

the nitrogen loading of estuaries. This is

significant since high nitrogen loadings

can lead to eutrophication of the

estuary, which causes disruption in the

ecological balance. The effect should be

most significant in areas heavily

affected by atmospheric NOX emissions.

One such estuary is Chesapeake Bay,

where as much as 40 percent of the

nitrogen loading may be caused by

atmospheric deposition. In addition to

these benefits, the NOX reductions from

the proposed new engine standards are

expected to have beneficial impacts

with respect to crop and forest damage.

B. Economic Impact and CostEffectiveness

This rulemaking does not follow the

normal pattern of allowing four years

following the conclusion of the rule

before requiring production of the new

low-emitting engines. The engine

manufacturers, by signing the Statement

of Principles, have committed

themselves to challenging, long-term

design targets. This provides

manufacturers fully eight years to

allocate resources and conduct planning

for a very thorough long-term R&D

program. Manufacturers have expressed

a confidence that several years of

research will provide them opportunity

to develop a complying engine that they

can market with full confidence.

The above presentation of the range of

technologies shows a good deal of

promise for controlling emissions, but

also makes clear that much effort

remains to optimize the technologies for

maximum emission-control

effectiveness with minimum negative

impacts on engine performance,

durability, and fuel consumption. On

the other hand, it has become clear that

manufacturers have a great potential to

advance beyond the current state of

understanding by identifying aspects of

the key technologies that contribute

most to hardware or operational costs or

other drawbacks and pursuing

improvements, simplifications, or

alternatives to limit those burdens. To

reflect this improvement and long-term

cost saving potential, the cost analysis

includes an estimated $230 million (net

present value in 1996) in R&D outlays

for heavy-duty engine emission control

over several years. The cost analysis

accordingly presumes extensive

improvements on the current state of

technology from these future

developments. The 1999 technology

review provides a check on EPA’s

projected costs. EPA will revisit the

analysis of the full life-cycle costs as

part of the 1999 technology review. EPA

and manufacturers will at that time

confirm whether or not technology

development is progressing as needed to

meet the proposed emission standards.

In assessing the economic impact of

changing the emission standards, EPA

has made a best estimate of the

combination of technologies that an

engine manufacturer might use to meet

the proposed standards at an acceptable

cost. Full details of EPA’s cost and costeffectiveness analyses, including

information not presented here, can be

found in the Regulatory Impact Analysis

in the public docket. The Agency invites

comments on all aspects of these

analyses.

Estimated cost increases are broken

into purchase price and total life-cycle

costs. The incremental purchase price

for new engines is comprised of variable

costs (for hardware and assembly time)

and fixed costs (for R&D, retooling, and

certification). Total life-cycle costs

factor in an additional estimate for

operating costs attributable to any

increased maintenance or fuel

consumption. Cost estimates based on

these projected technology packages

represent an expected incremental cost

of engines in the 2004 model year. Costs

in subsequent years would be reduced

by several factors, as described below.

Separate projected costs were derived

for engines used in three service classes

of heavy-duty diesel engines. Cost

estimates are presented for all gasoline

heavy-duty vehicles as a single group.

All costs are presented in 1996 dollars.

Life-cycle costs have been discounted to

the year of sale. Diesel engine costs are

considered first, followed by gasoline

engines.

1. Costs for Diesel Engines

The following discussion provides a

description and estimated costs for

those technologies EPA believes will be

needed to comply with the proposed

emission standards. It is difficult to

make a distinction between technologies

that are needed to reduce NOX

emissions for compliance with 2004

model year standards and those

technologies that offer other benefits for

improved fuel economy and engine

performance or for better control of

particulate emissions. EPA believes that

manufacturers, in the absence of 2004

model year standards, would continue

research on and eventually deploy

numerous technological upgrades to

improve engine performance or more

cost-effectively control emissions. EPA

therefore believes that a small set of

technologies represent the primary

changes manufacturers must make to

meet the proposed 2004 model year

standards. Other technologies applied to

heavy-duty engines, before or after

implementation of new emission

standards, will make relatively minor

positive contributions to controlling

NOX emissions and are therefore

considered secondary improvements for

this analysis. In this category are design

changes such as improved oil control,

variable-geometry turbochargers,

optimized catalyst designs, and

variable-valve timing. Lean NOX

catalysts are also considered here to be

secondary technologies, not because

NOX control is an incidental benefit, but

rather because it appears unlikely that

they will be part of 2004 model year

technology packages. Modifications to

fuel injection systems will also continue

independently of new standards, though

some further development with a focus

on reducing NOX emissions would be

evaluated.

Several technological improvements

are projected for complying with the

proposed 2004 model year emission

standards. Selecting this package of

technologies requires extensive

engineering judgment. The fact that

manufacturers have nearly a full decade

before implementation of the proposed

standards virtually ensures that the

technologies used to comply with the

proposed emission standards will

develop significantly before reaching

production. This ongoing development

will lead to reduced costs in three ways.

First, research will lead to enhanced

effectiveness for individual

technologies, allowing manufacturers to

use simpler packages of emission

control technologies than we would

predict given the current state of

development. Similarly, the continuing

effort to improve the emission control

technologies will include innovations

that allow lower-cost production.

Finally, manufacturers will focus

research efforts on any drawbacks, such

as increased fuel consumption or
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33463

51 ‘‘Learning Curves in Manufacturing,’’ Linda

Argote and Dennis Epple, Science, February 23,

1990, Vol. 247, pp. 920–924.

maintenance costs, in an effort to

minimize or overcome any potential

negative effects.

A combination of primary technology

upgrades are anticipated for the 2004

model year. Achieving very low NOX

emissions will require basic research on

reducing in-cylinder NOX and HC.

Modifications to basic engine design

features can be used to improve intake

air characteristics and distribution

during combustion. Manufacturers are

also expected to utilize upgraded

electronics and advanced fuel-injection

techniques and hardware to modify

various fuel injection parameters,

including injection pressure, further rate

shaping and some split injection. EPA

also expects that many engines will

incorporate light-load EGR.

If not developed and implemented

properly, EGR has the potential to

increase operating costs, either by

increasing fuel consumption or

requiring additional maintenance to

avoid accelerated engine or component

wear. While it is possible to develop

scenarios and estimate the impact on

operating costs of current diesel EGR

concepts, this is of minimal value due

to the expected continuing development

of these technologies. Nevertheless, EPA

has assessed the potential for increased

operating costs, as described below, first

for EGR-related maintenance, then for

fuel economy. EPA understands that

manufacturers will make a great effort to

minimize any potential new

maintenance burden for the end user,

investing in research to design an

engine acceptable to users. The cost to

address the durability concern is

therefore included not as a maintenance

item, but as a fixed cost. The analysis

includes a separate maintenance cost for

EGR systems—EPA expects engine

rebuilding will include preventive

maintenance to clean or replace EGR

components.

With respect to fuel economy, several

of the secondary technologies described

below may lead to cost savings, while

EGR has the potential to incur a fuel

economy penalty. As with potential new

maintenance cost burdens, EPA believes

manufacturers will focus their research

efforts on overcoming any negative

impact on fuel economy caused by EGR.

In any case, it is not clear at this stage

of development that the set of changes

resulting from the proposed emission

standards will have any net negative

impact on fuel economy; additional fuel

costs are therefore not included in the

cost analysis.

Meeting the proposed NOX+NMHC

standard will somewhat increase the

challenge to control particulate

emissions. Manufacturers might use a

number of different technologies to

maintain control of particulate

emissions; however, EPA believes that

the fuel system improvements described

above will be sufficient to prevent any

potential particulate-emission increase.

In fact, manufacturers are attempting to

lessen the cost of meeting current

particulate emission standards over the

next several years by decreasing their

reliance on catalysts. This underscores

EPA’s belief that 2004 model year

engines will be able to control

particulate emissions without major

technological innovation.

The costs of these new technologies

for meeting the proposed standards are

itemized in the Regulatory Impact

Analysis and summarized in Table 6.

For light heavy-duty vehicles, the

incremental cost of a new 2004 model

year engine is estimated to be $185,

with no additional operating costs. For

medium heavy duty vehicles the new

engine purchase price is estimated to

increase by $327, with total life-cycle

costs of $371. Similarly, for heavy

heavy-duty engines, initial purchase

price is expected to increase by $403,

while total life-cycle cost estimates

reach $499.

For the long term, EPA has identified

various factors that would cause cost

impacts to decrease over time. First, the

analysis incorporates the expectation

that manufacturers will apply ongoing

research to making emission controls

more effective and less costly over time.

This expectation is similar to

manufacturers’ stated goal of decreasing

their reliance on catalysts to meet

emission standards in the future.

Research in the costs of manufacturing

has consistently shown that as

manufacturers gain experience in

production, they are able to apply

innovations to simplify machining and

assembly operations, use lower cost

materials, and reduce the number or

complexity of component parts.51 The

analysis incorporates the effects of this

learning curve by projecting that the

variable costs of producing the lowemitting engines decreases by 20

percent starting with the third year of

production (2006 model year) and by

reducing variable costs again by 20

percent starting with the sixth year of

production. Finally, since fixed costs

are assumed to be recovered over a fiveyear period, these costs disappear from

the analysis after the first five model

years. Table 6 lists the projected

schedule of costs for each category of

vehicle over time.

TABLE 6.—PROJECTED DIESEL ENGINE COSTS

[1995 dollars discounted to year of sale]

Vehicle class Model year Purchase

price

Life-cycle

operating

cost

Total lifecycle cost

Light heavy-duty .................................................................... 2004 ....................................................................................... 185 0 185

2009 and later ....................................................................... 68 0 68

Medium heavy-duty ............................................................... 2004 ....................................................................................... 327 44 371

2009 and later ....................................................................... 101 44 145

Heavy heavy-duty .................................................................. 2004 ....................................................................................... 403 96 499

2009 and later ....................................................................... 148 96 243

2. Costs for Gasoline Engines

The cost analysis for gasoline engines

follows the same methodology as for

diesel engines, though with significantly

less complexity due to the expectation

that the technological development

needed to meet the proposed standards

will not be so far-reaching as for diesel

engines. The same kinds of costs are

considered for gasoline engines.

Because the technologies require

changes to existing technologies without

affecting the assembly time, no increase

in assembly costs are anticipated. Also,

the improvements to gasoline engine

technologies will not affect fuel

economy or in-use maintenance;

therefore, no incremental fuel or

maintenance costs are anticipated.

Gasoline engines and vehicles need a

much different set of changes to meet

the proposed emission standards than

do diesel engines. Much of the very

extensive development work done for
33464 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

52The RIA contains a detailed description of areas

included in the regional control strategy.

passenger cars can, with appropriate

adaptations, be applied to heavy-duty

engines. The technology projections for

heavy-duty gasoline engines therefore

depend in part on the experience with

light-duty trucks, as well as on the

current view of technology

developments for the heavy-duty

applications themselves.

More sophisticated control of EGR

flow rates over the various operating

modes may allow more aggressive use of

EGR to better control NOX emissions.

Ongoing developments show that threeway catalysts can be made with

modified washcoats and configured in

the vehicle in ways that significantly

improve their effectiveness at

controlling both NOX and HC emissions.

Some basic engine modifications may

also be needed to fine-tune emission

control and operating performance.

Since no operating costs for fuel

economy or maintenance are expected

for gasoline engines, all the costs

translate into an increased purchase

price of the engine or vehicle. The 2004

model year cost estimate for an average

heavy-duty gasoline vehicle is $162.

Costs can be reduced with continuing

production experience, as described for

diesel engines; variable costs are

reduced by 20 percent only one time

though, because the changes to gasoline

engines are considered to be of a smaller

magnitude. The resulting cost

calculation for 2009 and later model

year heavy-duty gasoline vehicles is

$101 (Table 7).

TABLE 7.—PROJECTED GASOLINE

ENGINE COSTS

[1995 dollars discounted to year of sale]

Model

year

Purchase

price

Life-cycle

operating

cost

Total lifecycle cost

2004 ...... 162 0 162

2009 and

later .... 101 0 101

3. Aggregate Costs to Society

The above analysis develops pervehicle cost estimates for each vehicle

class. Using current data for the size and

characteristics of the heavy-duty vehicle

fleet and making projections for the

future, these costs can be used to

estimate the total cost to the nation for

the proposed emission standards in any

year. The result of this analysis is a

projected total cost starting at $300

million in 2004. Per-vehicle costs

savings over time reduce projected costs

to a minimum value of $136 million in

2009, after which the growth in truck

population leads to increasing costs that

reach $186 million in 2020. Total costs

for these years are presented by vehicle

class in Table 8. The calculated total

costs represent a combined estimate of

fixed costs as they are allocated over

fleet sales, variable costs assessed at the

point of sale, and operating costs as they

are incurred in each calendar year.

TABLE 8.—ESTIMATED ANNUAL COSTS

FOR IMPROVED HEAVY-DUTY VEHICLES

[millions of dollars]

Category 2004 2009 2020

Light

HeavyDuty

Diesel 51 23 26

Medium

HeavyDuty

Diesel 71 22 34

Heavy

HeavyDuty

Diesel 97 37 62

Gasoline 81 55 64

Total ...... 300 136 186

As described in Section X below, EPA

expects that complying with the

proposed emission standards will not

result in a significant impact on a

substantial number of small entities.

4. Cost-effectiveness

EPA has estimated the per-vehicle

cost-effectiveness (i.e., the cost per ton

of emission reduction) of the proposed

NOX plus NMHC standard over the

typical lifetime of heavy-duty diesel and

heavy-duty gasoline vehicles. The RIA

contains a more detailed discussion of

the cost-effectiveness analyses. EPA

requests comments on all aspects of the

cost-effectiveness analyses, including,

for example, the appropriateness of the

scope of benefits and costs which EPA

considered.

EPA has examined the costeffectiveness by two different

methodologies. The first methodology

yields a nationwide cost-effectiveness in

which the total cost of compliance is

divided by the nationwide emission

benefits. The second methodology

yields a regional ozone strategy costeffectiveness in which the total cost of

compliance is divided by the emission

benefits attributable to the regions that

impact ozone levels in ozone

nonattainment areas.52 EPA requests

comments on the methodologies used to

determine cost-effectiveness in this

analysis.

In addition to the benefits of reducing

ozone within and transported into urban

ozone nonattainment areas, the NOX

reductions from the proposed new

engine standards are expected to have

beneficial impacts with respect to crop

damage, secondary particulate, acid

deposition, eutrophication, visibility,

and forests, as described above. Due to

the difficulty in estimating the monetary

value of these societal benefits, the costeffectiveness analysis does not assign

any numerical value to these additional

benefits. It should be emphasized that

the Agency believes that the actual

monetary value of the multiple

environmental and public health

benefits produced by the large NOX

reductions under this proposal is likely

to be much higher than the estimated

regulatory costs. To the extent possible,

EPA plans to take into consideration the

value of these additional benefits in

analyzing the cost-effectiveness of the

standards for the final rulemaking. EPA

requests comment on including these

benefits in an estimate of the costeffectiveness of the proposed standards.

As described above in the cost

section, the cost of complying with the

proposed standards will vary by model

year. Therefore, the cost-effectiveness

will also vary from model year to model

year. For comparison purposes, the

discounted costs, emission reductions

and cost-effectiveness of the proposed

standards are shown in Table 9 for the

same model years discussed above in

the cost section. The cost-effectiveness

results contained in Table 9 present the

range in cost-effectiveness resulting

from the two cost-effectiveness

scenarios described above.
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33465

TABLE 9.—DISCOUNTED PER-VEHICLE COSTS, EMISSION REDUCTIONS AND COST-EFFECTIVENESS OF THE PROPOSED

NOX and NMHC Standards

Vehicle class Model year

Discounted

lifecycle

cost

Discounted lifetime reductions (tons) Discounted

cost-effectiveness ($/ton) NOX NMH

Heavy-duty diesel vehicles ................................................................... 2004 $333 1.321 0.019 $200–$300

2009+ 143 .................... .................... 100

Heavy-duty gasoline vehicles ............................................................... 2004 162 0.190 0.011 800–900

2009+ 101 .................... .................... 500–600

VI. Potential for Use of Additional

Incentive-based Approaches

When considering how to achieve the

greatest emission reductions possible, a

broad variety of options must be

evaluated. On one end of the continuum

are mandatory standards, which

generally provide the strongest

mechanism to produce cleaner engines.

At the other end of the continuum are

voluntary programs, where engine

manufacturers and users are not

required to make or use cleaner engines,

but are strongly encouraged to do so.

The proposed actions described in

Section IV above include elements of

both mandatory programs (emissions

standards and durability-related

requirements), as well as voluntary

provisions (enhancements to the

averaging banking and trading program).

Voluntary programs can also be used to

allow manufacturers and users

maximum flexibility in finding the most

cost effective ways to adopt new

standards.

In the following sections, EPA

describes additional voluntary programs

that might facilitate the introduction of

cleaner heavy-duty engines. These are

voluntary labeling (‘‘green star’’)

programs, and emission reduction credit

generation under various state-run

credit programs (including scrappage

buy-back and open market trading).

While EPA is not proposing these

programs in today’s NPRM, EPA is

soliciting comments on their

applicability and potential usefulness.

A. Voluntary Labeling

One type of economic incentive

program is environmental labeling, or

‘‘green’’ labeling. While ‘‘green’’

labeling is very closely linked to

environmental marketing, it most often

involves setting voluntary standards and

encouraging industry to adopt them

based on their intrinsic value to the

common good, as well as individual

companies. In a voluntary labeling

program benefits can be direct or

indirect. Some voluntary labeling

programs may confer direct economic

benefits (savings), for example, in the

form of reduced energy costs. An

example of this is EPA’s Green Lights

and Energy Star programs. Other

voluntary labeling programs may confer

only indirect benefits on companies that

offset emission control costs by

providing some other intangible benefit,

such as positive publicity, public

goodwill, or improved efficiency.

Although EPA is not proposing a

voluntary environmental labeling

program in this document, EPA is

requesting comments on a threecomponent labeling concept called the

Green Star Engines Program. The

program would seek to identify cleaner

engines and classify products that could

be marketed as ‘‘green.’’ This would

provide positive publicity and,

potentially, economic incentives. These,

in turn, could help encourage engine

manufacturers to market cleaner engines

and encourage truckers and other users

to purchase those cleaner engines.

The first part of the program would

focus on identifying engines that meet

the emission standards contained in

today’s proposal earlier than required.

The second would also focus on early

compliance, but with intermediate

standards which are between pre-2004

levels and those being proposed today.

The third part of the program would

concentrate on identifying engines that

can meet or exceed the emissions

standard with the use of alternative

fuels. Engine manufacturers benefit

from the public good will created as

they demonstrate a commitment to work

cooperatively with other stakeholders to

improve air quality. In addition,

producers of alternative fuels would

have additional opportunities to enter

the transportation energy market.

As described further below, engines

falling under any of the three parts of

the program would be identified with an

appropriate engine label. Trucks

equipped with such engines would also

be labeled. In the case of the truck

labels, it might be desirable to include

a commitment to advanced maintenance

practices on the part of the truck owner

as a condition of displaying the label.

EPA envisions that this could be a

cooperative program between the

federal or state government and truck

owners/operators. Participants would

sign a letter of commitment to establish

specified maintenance programs and

maintenance technician training

programs. They would then be

recognized as members of the program

and provided with labels to affix to their

trucks. The supervising agency, either

EPA or some other entity, would be

responsible for ascertaining that truck

owner/operators have the systems in

place to comply with the maintenance

requirements. Also, the commitment

would have to be renewed periodically

to insure that the relevant trucks are

performing as required.

EPA solicits comment as to the

practicality and potential effectiveness

of all aspects of this program, as well as

whether and how the three aspects of

the program could be used

simultaneously, as further discussed

below.

EPA anticipates that a broad range of

interested stakeholders would wish to

participate in the Green Star Programs

described in more detail below.

Interested stakeholders would

participate as either a Partner or

Supporter. A Partner would be defined

as an individual or entity that either

manufactures or uses the Green Star

Product and thus has a greater stake in

the program outcome. A Supporter

would assist in making the program

successful through public education

efforts and by providing positive

publicity.

1. Green Star Engine Program: Early

Compliance with Certification

Standards

The first labeling program about

which EPA is requesting comment

would identify those heavy-duty

engines which meet the federal heavyduty certification standards prior to the

required implementation date. All such

engines would be identified with the

Green Star Engine Label. Trucks that are

equipped with Green Star engines

would also be identified with the Green

Star Engine Label.
33466 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

The identification of heavy-duty

engines, trucks, and equipment that

meet a more protective standard would

serve to visually inform users, states,

interested parties, and the general

public of the specific heavy-duty

engines, and consequently the trucks

and other heavy-duty equipment, which

meet more protective emission

standards. For example, heavy-duty

engines which meet the 1998 NOX

standard before 1998 could be labeled

with a Green Star Engine label, until

those standards become mandatory.

After those standards are mandatory,

but prior to the implementation to the

2004 heavy-duty standard, heavy-duty

engines that meet the 2004 standards

could be labeled with the Green Star

Engine label. This program would be

intended to encourage the early

introduction of cleaner heavy-duty

engines, the idea being that early users

would draw some publicity benefits

from using these engines. Engine

manufacturers would benefit from being

able to use the Green Star Engine label

as a sales tool. Comments are invited on

whether EPA should propose the early

compliance labeling program, and if it

should, how the program should be

structured.

2. Green Star Engine: Intermediate

Standards Program

Engines which might meet a more

stringent intermediate standard than

what would be required by regulation

could be identified with the Green Star

Engine intermediate label. The

intermediate label would identify

engines (and trucks equipped with those

engines) as cleaner than the current

standard but not as clean as the future

standard. For example, such an engine

might meet a 2.5–3.0 g/bhp-hr NOX

standard between 1998 and 2004 or

meet a 1–1.5 gram NOX standard after

2004. For the 2004 case, it may be

desirable to have a somewhat higher cut

point initially, and then lower it over

time. Engines certified to meet an

intermediate standard would be

demonstrating more advanced

technology options than other engines.

The Agency would expect that

advantages similar to the early

certification program would accrue for

any potential participants. Of course,

the intermediate standards component

of the Green Star Engine labeling

program would not accrue the same

level of potential air quality benefit as

the early certification component

described above because the emission

standards would not be as stringent.

EPA requests comments on the

feasibility of developing an intermediate

standard labeling program. Commenters

supporting a proposal are also asked to

comment on the appropriateness of

using a 3g/bhp-hr NOX level as a cutpoint for the 1998 to 2004 time period,

as well as an appropriate cut point, or

points, for 2004 and later.

3. Green Star Alternative Fuel Engines

Under this component of the program,

all engines which meet or exceed the

1998 or 2004 standards by using

alternative fuels would be identified

with a Green Star Alternative fuel

engine label. Trucks using those engines

would also be labeled. The primary

purpose would be to encourage the use

of alternative fuels by identifying the

engines/trucks which meet or exceed

the proposed emission standards by

utilizing alternative fuels (such as CNG,

methanol, or LPG) as their energy

source. The use of alternative fuels can

bring additional benefits, such as

reduced green house gas emissions, not

available with conventional fuels.

Alternative fuels could be included in

the labeling program in conjunction

with either of the other two components

of the Green Star Engine program. EPA

requests that comments be submitted

regarding the usefulness and practicality

of an alternative fuel engine labeling

program. The Agency also asks that

comments be submitted on the logistical

aspects of a labeling program for such

an approach.

B. Emission Reduction Credit Programs

A third type of economic incentive

program involves generating and trading

emission reduction credits. This type of

incentive could be used by those states

that have adopted economic incentive

programs in their State Implementation

Plan, and would be subject to the details

of those programs. Where they are

available, these programs could provide

an incentive for engine manufacturers

and truck operators to undertake

emission reduction efforts beyond those

required since states may allow such

emission sources to generate and sell

emission reduction credits to other

entities such as stationary sources.

Alternatively, the generator of the

credits could retain them for use or sale

in the future. The purchaser of the

credits would typically use the credits

to offset their own emission reduction

requirements and therefore the credits

may not of themselves reduce overall

emissions. Another option available in

credit programs is for the purchaser to

retire the credits to benefit the

environment instead of using them to

offset emission reduction requirements.

Retiring credits would result in an

overall reduction in emissions. Credits

programs could lower the overall cost of

emission reductions by allowing for

more cost effective emissions controls to

be used on some emissions sources

instead of less cost effective controls on

other sources. Additionally, credits

programs may encourage technology

advances that may have broad

applications, which could help lower

overall emissions in the future.

There are two important credit trading

programs of this kind: the Economic

Incentive Program (EIP) and the

proposed Open Market Trading Rule

(OMTR) (60 FR 39668, August 3, 1995).

Generally, the EIP is more stringent than

the proposed OMTR in that it requires

state approval for trades before they

occur. However, these programs are

similar in that they require credits to be

surplus (beyond required emissions

reductions), quantifiable, and

enforceable.

Because credits must be surplus,

engines generating credits for use in

EPA’s averaging, banking, and trading

(ABT) program cannot also generate

marketable emission reduction credits,

based on those same emission

reductions, to be used in the credit

trading programs. That is, a truck

operator cannot generate emission

reduction credits based on the

difference between the emissions level

of the engine and the standard if that

engine is generating credits for use by

the manufacturer in the ABT program.

EPA believes that some manufacturers

may choose to pass credit ownership to

purchasers of clean engines rather than

using the credits themselves under the

ABT program. EPA believes that in

some circumstances this could well be

appropriate and consistent with the

intent of the ABT regulations. Further

discussion is provided in section III.B.3.

above.

Depending on the state program, truck

operators may be able to generate credits

in ways other than purchasing cleanerthan-required engines. For example,

credits might be able to be generated

through operational changes,

maintenance changes, or changes in

activity levels. Credits might also be

earned through buy-back programs,

commonly known as scrappage

programs. Buy-back programs typically

involve giving financial incentives to

vehicle owners in exchange for the

voluntary scrapping of their oldertechnology, higher-emitting engines or

vehicles. Buy-back programs might also

be used for helping an area achieve an

air quality goal rather than to generate

emission reduction credits to be sold in

an emission trading program (for

example, in the proposed Open Market

Trading Rule). Typically, any credits

earned in buy-back programs are earned
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33467

53The 1994 California Ozone SIP includes both

the proposed national HDE measure and 3 proposed

State measures for HDEs. The California Ozone SIP

also includes other national mobile source

measures for nonroad engines, ships, aircraft, and

pleasure craft as components of the attainment

demonstration for the South Coast nonattainment

area. For further details on the California Ozone

SIP, see 61 FR 10920–10962 (March 18, 1996).

by those purchasing and retiring the old

vehicles or engines. As long as the

emission benefits that result can be

reliably quantified and meet the

requirements of the relevant state credit

program, such activities could be used

to generate emission reduction credits.

VII. Public Participation

As mentioned above, EPA issued an

Advance Notice of Proposed

Rulemaking (ANPRM) announcing

EPA’s intent to formally propose

regulatory action relating to HDE

emissions, including today’s action on

highway HDEs. During the development

of the ANPRM and after its publication,

EPA received a wide range of early

comments on the basic framework of

such a program. By the time of the close

of the comment period, the Agency had

received more than 60 communications

relating to this program and the

ANPRM. These comments have been

very valuable in developing today’s

proposal, and the Agency looks forward

to additional comment as the formal

rulemaking process now begins.

As described in part in the

discussions above, comments ranged

from those strongly opposing new

highway HDE emission standards like

those proposed today to those strongly

supportive of such new standards or of

standards even more stringent.

Commenters offered widely varying

rationales for their suggestions,

including the availability or

nonavailability of cost effective engine

technology or the degree of need for

new NOX and PM control. To the extent

possible, EPA has considered each of

the comments relevant to highway HDE

emissions and has accommodated them

in this proposal. (Comments relating to

other potential parts of an overall

program that are not proposed today,

including regulations affecting fuels or

nonroad engines, are under

consideration by the Agency as it

contemplates what action it may pursue

in these areas in the future.) To the

extent commenters on the ANPRM

believe EPA failed to address their

ANPRM comments adequately in this

proposal, they should offer them again

as comments to this NPRM for

consideration in this rulemaking.

A. Comments and the Public Docket

EPA today opens a formal comment

period for this NPRM and will accept

comments through August 26, 1996. The

Agency encourages all parties that have

an interest in the program proposed

today to offer comment on all aspects of

this action. Throughout this proposal

are requests for specific comment on

various topics. Of particular interest to

the Agency are detailed comments in

the following areas: The air quality need

for national or regional NOX, PM, and

VOC control; the need for control of

emissions from highway HDEs; EPA’s

proposed approaches to encouraging

durability and revising the Averaging,

Banking, and Trading program; the

technological feasibility of the proposed

standards; EPA’s projections of the

environmental and economic impacts of

the proposed program; and nonregulatory methods of encouraging early

compliance or cleaner-than-required

engines.

The most useful comments are those

supported by appropriate and detailed

rationales, data, and analyses. The

Agency also encourages commenters

that disagree with the proposed program

to suggest and analyze alternate

approaches to meeting the air quality

goals of this proposed program. All

comments, with the exception of

proprietary information, should be

directed to the EPA Air Docket Section,

Docket No. A–95–27 before the date

specified above.

Commenters who wish to submit

proprietary information for

consideration should clearly separate

such information from other comments

by (1) labeling proprietary information

‘‘Confidential Business Information’’

and (2) sending proprietary information

directly to the contact person listed (see

FOR FURTHER INFORMATION CONTACT) and

not to the public docket. This will help

ensure that proprietary information is

not inadvertently placed in the docket.

If a commenter wants EPA to use a

submission of confidential information

as part of the basis for the final rule,

then a nonconfidential version of the

document that summarizes the key data

or information should be sent to the

docket.

Information covered by a claim of

confidentiality will be disclosed by EPA

only to the extent allowed and in

accordance with the procedures set

forth in 40 CFR part 2. If no claim of

confidentiality accompanies the

submission when it is received by EPA,

it will be made available to the public

without further notice to the

commenter.

B. Public Hearing

The Agency will hold a public

hearing as noted in the DATES section

above. Any person desiring to present

testimony at the public hearing is asked

to notify the contact person listed above

at least five business days prior to the

date of the hearing. This notification

should include an estimate of the time

required for the presentation of the

testimony and any need for audio/visual

equipment. EPA suggests that sufficient

copies of the statement or material to be

presented be available to the audience.

In addition, it is helpful if the contact

person receives a copy of the testimony

or material prior to the hearing.

The hearing will be conducted

informally, and technical rules of

evidence will not apply. A sign-up sheet

will be available at the hearing for

scheduling the order of testimony. A

written transcript of the hearing will be

prepared. The official record of the

hearing will be kept open for 30 days

after the hearing to allow submittal of

supplementary information.

In addition to the public hearing, EPA

will hold a public meeting in Los

Angeles to discuss the proposed EPA

regulations for HDEs, and receive

informal public input on them. Other

potential mobile source controls

identified in the California Ozone State

Implementation Plan for the South

Coast (the greater Los Angeles area) will

also be discussed.53 Further details on

the public meeting may be found in the

DATES section at the beginning of this

document. Because this public meeting

is intended to be an informal exchange

of information, a transcript of the

meeting will not be prepared and

members of the public who wish to

present comments at the Los Angeles

meeting should be aware that, in order

to be considered for the final

promulgation, their comments must also

be made either in writing to the

rulemaking docket or at the public

hearing.

VIII. Statutory Authority

Section 202(a)(3) authorizes EPA to

establish emissions standards for new

heavy-duty motor vehicle engines. See

42 U.S.C. 7521(a)(3). These standards

are to reflect the greatest reduction

achievable through the application of

technology which the Administrator

determines will be available, giving

appropriate consideration to cost,

energy, and safety factors associated

with the application of such technology.

This provision also establishes the lead

time and stability requirements for these

standards, and in addition authorizes

EPA to establish requirements to control

rebuilding practices for heavy-duty

engines. Pursuant to Sections 202(a)(1)

and 202(d), these emissions standards
33468 Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules

54EPA Docket A–95–27, II–D–41.

apply for the useful life period

established by the Agency. See 42

U.S.C. 7521(a)(1), 7521(d). EPA’s

authority to issue a certificate of

conformity upon payment of a noncompliance penalty established by

regulations is found in Section 206(g) of

the Act. See 42.U.S.C. 7525(g). Other

provisions of Title II of the Act, along

with Section 301, are additional

authority for the measures proposed in

this action.

IX. Administrative Designation and

Regulatory Analysis

Under Executive Order 12866 (58 FR

51735 (Oct. 4, 1993)), the Agency must

determine whether this regulatory

action is ‘‘significant’’ and therefore

subject to OMB review and the

requirements of the Executive Order.

The order defines ‘‘significant

regulatory action’’ as any regulatory

action that is likely to result in a rule

that may:

(1) Have an annual effect on the

economy of $100 million or more or

adversely affect in a material way the

economy, a sector of the economy,

productivity, competition, jobs, the

environment, public health or safety, or

State, local, or tribal governments or

communities;

(2) Create a serious inconsistency or

otherwise interfere with an action taken

or planned by another agency;

(3) materially alter the budgetary

impact of entitlements, grants, user fees,

or loan programs or the rights and

obligations of recipients thereof; or,

(4) raise novel legal or policy issues

arising out of legal mandates, the

President’s priorities, or the principles

set forth in the Executive Order.

Pursuant to the terms of Executive

Order 12866, EPA has determined that

this proposal is a ‘‘significant regulatory

action’’ because the proposed standards

and other regulatory provisions, if

implemented, would have an annual

effect on the economy in excess of $100

million. A Regulatory Impact Analysis

has been prepared and is available in

the docket associated with this

rulemaking. This action was submitted

to the Office of Management and Budget

(OMB) for review as required by

Executive Order 12866. Any written

comments from OMB and any EPA

response to OMB comments are in the

public docket for this proposal.

X. Impact on Small Entities and

Compliance With Regulatory Flexibility

Act

The Regulatory Flexibility Act of 1980

requires federal agencies to identify

potentially adverse impacts of federal

regulations upon small entities. In

instances where significant impacts are

possible on a substantial number of

these entities, agencies are required to

perform a Regulatory Flexibility

Analysis.

EPA certifies that the new emission

standards and other related provisions

proposed in this action will not have a

significant impact on a substantial

number of small entities, since none of

the engine manufacturers affected by

these regulations is a small business

entity.

This action also proposes provisions

clarifying what would and would not be

considered a prohibited act (tampering)

under CAA Section 203 during the

heavy-duty engine rebuilding process.

Small businesses are integral to the

heavy-duty engine rebuilding industry

as noted in comments provided by the

Automotive Engine Rebuilders

Association.54 However, EPA does not

believe that the proposals related to

engine rebuilding will have a significant

impact on a substantial number of these

small entities. EPA is proposing to

define how a broad existing requirement

(CAA Section 203) applies specifically

to the process of rebuilding engines, but

EPA is not creating a new program.

Second, during the development of the

proposal EPA consulted with the Engine

Manufacturers Association, the

Automotive Engine Rebuilders

Association, and the Production Engine

Rebuilders Association, associations

which together represent a substantial

portion of the engine rebuilding and

related businesses. These organizations

did not raise concerns that the proposal

may have a significant impact on small

businesses. EPA requests comments on

the proposals regarding engine

rebuilding, any significant effect that the

proposals would have on small

businesses, and the reasons why such

effects might occur.

XI. Compliance With Paperwork

Reduction Act

The information collection

requirements in this proposed rule have

been submitted for approval to the

Office of Management and Budget

(OMB) under the Paperwork Reduction

Act, 44 U.S.C. 3501 et seq. An

Information Collection Request (ICR)

document has been prepared by EPA

(ICR No. 783.35) and a copy may be

obtained from Sandy Farmer, Regulatory

Information Division’ U.S.

Environmental Protection Agency

(2136); 401 M St., SW., Washington, DC

20460 or by calling (202) 260–2740.

The information we propose to collect

includes certification results, durability,

maintenance, and averaging, banking

and trading information. This

information will be used to ensure

compliance with and enforce the

provisions in this rule. Section 208 (a)

of the CAA requires that manufacturers

provide information the Administrator

may reasonably require to determine

compliance with the regulations,

therefore submission of the information

is mandatory. EPA will consider

confidential all information which

meets the requirements of § 208 (c) of

the CAA.

EPA estimates the average first year

hours burden per response to be 4,670,

the proposed frequency of response to

be annual, and the estimated number of

likely respondents to be twenty. EPA

estimates the aggregate first year hours

burden to be 93,410. EPA estimates the

annual first year cost to be $5,603,280,

including the annualized capital and

start-up costs. Subsequent year burdens

are estimated to be one-tenth of the first

year estimates due to the practice of

engine family carry-over from model

year-to-model year. Burden means the

total time, effort, or financial resources

expended by persons to generate,

maintain, retain, or disclose or provide

information to or for a Federal agency.

This includes the time needed to review

instructions; develop, acquire, install,

and utilize technology and systems for

the purposes of collecting, validating,

and verifying information, processing

and maintaining information, and

disclosing and providing information;

adjust the existing ways to comply with

any previously applicable instructions

and requirements; train personnel to be

able to respond to a collection of

information; and transmit or otherwise

disclose the information.

An Agency may not conduct or

sponsor, and a person is not required to

respond to a collection of information

unless it displays a currently valid OMB

control number. The OMB control

numbers for EPA’s regulations are listed

in 40 CFR Part 9 and 48 CFR Chapter

15.

Comments are requested on the

Agency’s need for this information, the

accuracy of the provided burden

estimates, and any suggested methods

for minimizing respondent burden,

including through the use of automated

collection techniques. Send comments

on the ICR to the Director, OPPE

Regulatory Information Division; U.S.

Environmental Protection Agency

(2136); 401 M St., S.W.; Washington, DC

20460; and to the Office of Information

and Regulatory Affairs, Office of

Management and Budget, 725 17th St.,

NW., Washington, DC 20503, marked

‘‘Attention: Desk Officer for EPA.’’
Federal Register / Vol. 61, No. 125 / Thursday, June 27, 1996 / Proposed Rules 33469

Include the ICR number in any

correspondence. Since OMB is required

to make a decision concerning the ICR

between 30 and 60 days after June 27,

1996, a comment to OMB is best assured

of having its full effect if OMB receives

it by July 29, 1996. The final rule will

respond to any OMB or public

comments on the information collection

requirements contained in this proposal.

XII. Unfunded Mandates Reform Act

Title II of the Unfunded Mandates

Reform Act of 1995 (UMRA), P.L. 104–

4, establishes requirements for Federal

agencies to assess the effects of their

regulatory actions on State, local, and

tribal governments and the private

sector. Under section 202 of the UMRA,

EPA generally must prepare a written

statement, including a cost-benefit

analysis, for proposed and final rules

with ‘‘Federal mandates’’ that may

result in expenditures to state, local,

and tribal governments, in the aggregate,

or to the private sector, of $100 million

or more for any one year. Before

promulgating an EPA rule for which a

written statement is needed, section 205

of the UMRA generally requires EPA to

identify and consider a reasonable

number of regulatory alternatives and

adopt the least costly, most cost

effective, or least burdensome

alternative that achieves the objectives

of the rule. The provisions of section

205 do not apply when they are

inconsistent with applicable law.

Moreover, section 205 allows EPA to

adopt an alternative other than the least

costly, most cost effective, or least

burdensome alternative if the

Administrator publishes with the final

rule an explanation of why that

alternative was not adopted. Before EPA

establishes any regulatory requirements

that may significantly or uniquely affect

small governments, including tribal

governments, it must have developed

under section 203 of the UMRA a small

government agency plan. The plan must

provide for notifying potentially

affected small governments, enabling

officials of affected small governments

to have meaningful and timely input in

the development of EPA regulatory

proposals with significant federal

intergovernmental mandates, and

informing, educating, and advising

small governments on compliance with

the regulatory requirements.

Today’s rule contains no Federal

mandates (under the regulatory

provisions of Title II of the UMRA) for

State, local, or tribal governments. The

rule imposes no enforceable duties on

any of these governmental entities.

Nothing in the proposed program would

significantly or uniquely affect small

governments. EPA has determined that

this rule contains federal mandates that

may result in expenditures of $100

million or more in any one year for the

private sector. EPA believes that the

proposed program represents the least

costly, most cost-effective approach to

achieving the air quality goals of the

proposed rule. EPA has performed the

required analyses under Executive

Order 12866 which contains identical

analytical requirements. The reader is

directed to section IX, Administrative

Designation and Regulatory Analysis,

for further information regarding these

analyses.

XIII. Copies of Rulemaking Documents

The preamble, draft regulatory

language and draft Regulatory Impact

Analysis (RIA) are available in the

public docket as described under

ADDRESSES above and is also available

electronically on the Technology

Transfer Network (TTN), which is an

electronic bulletin board system (BBS)

operated by EPA’s Office of Air Quality

Planning and Standards and via the

internet. The service is free of charge,

except for the cost of the phone call.

A. Technology Transfer Network (TTN)

Users are able to access and download

TTN files on their first call using a

personal computer and modem per the

following information.

TTN BBS: 919–541–5742 (1200–14400

bps, no parity, 8 data bits, 1 stop bit)

Voice Helpline: 919–541–5384

Also accessible via Internet: TELNET

ttnbbs.rtpnc.epa.gov Off-line:

Mondays from 8:00 AM to 12:00 Noon

ET

A user who has not called TTN

previously will first be required to

answer some basic informational

questions for registration purposes.

After completing the registration

process, proceed through the following

menu choices from the Top Menu to

access information on this rulemaking.

<T> GATEWAY TO TTN TECHNICAL

AREAS (Bulletin Boards)

<M> OMS—Mobile Sources Information

<K> Rulemaking & Reporting

<5> Heavy-duty/Diesel

<1> File area #1...Heavy-duty Truck and

Bus Standards

At this point, the system will list all

available files in the chosen category in

reverse chronological order with brief

descriptions. To download a file, select

a transfer protocol that is supported by

the terminal software on your own

computer, then set your own software to

receive the file using that same protocol.

If unfamiliar with handling

compressed (i.e. ZIP’ed) files, go to the

TTN top menu, System Utilities

(Command: 1) for information and the

necessary program to download in order

to unZIP the files of interest after

downloading to your computer. After

getting the files you want onto your

computer, you can quit the TTN BBS

with the <G>oodbye command.

Please note that due to differences

between the software used to develop

the document and the software into

which the document may be

downloaded, changes in format, page

length, etc. may occur.

B. Internet

Rulemaking documents may be found

on the internet as follow:

World Wide Web

http://www.epa.gov/omswww

FTP

ftp://ftp.epa.gov Then CD to the /pub/

gopher/OMS/ directory

Gopher

gopher://gopher.epa.gov:70/11/Offices/

Air/OMS

Alternatively, go to the main EPA

gopher, and follow the menus:

gopher.epa.gov

EPA Offices and Regions

Office of Air and Radiation

Office of Mobile Sources

List of Subjects in 40 CFR Part 86

Environmental protection,

Administrative practice and procedure,

Air pollution control, Motor vehicles,

Motor vehicles pollution, Reporting and

recordkeeping requirements, Research.

Dated: June 19, 1996.

Carol M. Browner,

Administrator.

[FR Doc. 96–16330 Filed 6–26–96; 8:45 am]

BILLING CODE 6560–50–P

40 CFR Parts 180, 185 and 186

[OPP–300433; FRL–5380–9]

RIN 2070–AC18

Glyphosate; Proposed Revision of

Tolerances

AGENCY: Environmental Protection

Agency (EPA).

ACTION: Proposed rule.

SUMMARY: EPA has completed the

reregistration process and issued a

Reregistration Eligibility Decision

document (RED) for the herbicide

glyphosate (N-phosphonomethyl

glycine). In the reregistration process,

all information to support a pesticide’s

continued registration is reviewed for