Tuesday, 

June 29, 2004 

Part II 

Environmental 

Protection Agency 

40 CFR Parts 9, 69, et al. 

Control of Emissions of Air Pollution 

From Nonroad Diesel Engines and Fuel; 

Final Rule 
38958 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 9, 69, 80, 86, 89, 94, 1039, 

1048, 1051, 1065, and 1068 

[OAR–2003–0012; FRL–7662–4] 

RIN 2060–AK27 

Control of Emissions of Air Pollution 

From Nonroad Diesel Engines and Fuel 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: Nonroad diesel engines 

contribute considerably to our nation’s 

air pollution. These engines, used 

primarily in construction, agricultural, 

and industrial applications, are 

projected to continue to contribute large 

amounts of particulate matter, nitrogen 

oxides, and sulfur oxides, all of which 

contribute to serious public health 

problems in the United States. These 

problems include premature mortality, 

aggravation of respiratory and 

cardiovascular disease, aggravation of 

existing asthma, acute respiratory 

symptoms, chronic bronchitis, and 

decreased lung function. We believe 

that diesel exhaust is likely to be 

carcinogenic to humans by inhalation. 

Today, EPA is adopting new emission 

standards for nonroad diesel engines 

and sulfur reductions in nonroad diesel 

fuel that will dramatically reduce 

harmful emissions and will directly 

help States and local areas recently 

designated as 8-hour ozone 

nonattainment areas to improve their air 

quality. This comprehensive national 

program regulates nonroad diesel 

engines and diesel fuel as a system. New 

engine standards will begin to take 

effect in the 2008 model year, phasing 

in over a number of years. These 

standards are based on the use of 

advanced exhaust emission control 

devices. We estimate particulate matter 

reductions of 95 percent, nitrogen 

oxides reductions of 90 percent, and the 

virtual elimination of sulfur oxides from 

nonroad engines meeting the new 

standards. Nonroad diesel fuel sulfur 

reductions of more than 99 percent from 

existing levels will provide significant 

health benefits as well as facilitate the 

introduction of high-efficiency catalytic 

exhaust emission control devices as 

these devices are damaged by sulfur. 

These fuel controls will be phased-in 

starting in mid-2007. Today’s nonroad 

final rule is largely based on the 

Environmental Protection Agency’s 

2007 highway diesel program. 

To better ensure the benefits of the 

standards are realized in-use and 

throughout the useful life of these 

engines, we are also adopting new test 

procedures, including not-to-exceed 

requirements, and related certification 

requirements. The rule also includes 

provisions to facilitate the transition to 

the new engine and fuel standards and 

to encourage the early introduction of 

clean technologies and clean nonroad 

diesel fuel. We have also developed 

provisions for both the engine and fuel 

programs designed to address small 

business considerations. 

The requirements in this rule will 

result in substantial benefits to public 

health and welfare through significant 

reductions in emissions of nitrogen 

oxides and particulate matter, as well as 

nonmethane hydrocarbons, carbon 

monoxide, sulfur oxides, and air toxics. 

We are now projecting that by 2030, this 

program will reduce annual emissions 

of nitrogen oxides and particulate 

matter by 738,000 and 129,000 tons, 

respectively. These emission reductions 

will prevent 12,000 premature deaths, 

over 8,900 hospitalizations, and almost 

a million work days lost, and will 

achieve other quantifiable benefits every 

year. The total benefits of this rule will 

be approximately $80 billion annually 

by 2030. The substantial health and 

welfare benefits we are projecting for 

this final action exceed those we 

anticipated at the time of this proposal. 

Costs for both the engine and fuel 

requirements will be many times less, at 

approximately $2 billion annually. 

DATES: This final rule is effective on 

August 30, 2004. 

The incorporation by reference of 

certain publications listed in this 

regulation is approved by the Director of 

the Federal Register as of August 30, 

2004. 

ADDRESSES: EPA has established a 

docket for this action under Docket ID 

Nos. OAR–2003–0012 and A–2001–28. 

All documents in the docket are listed 

in the EDOCKET index at http:// 

www.epa.gov/edocket. Although listed 

in the index, some information is not 

publicly available, i.e., CBI or other 

information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

is not placed on the Internet and will be 

publicly available only in hard copy 

form. Publicly available docket 

materials are available either 

electronically in EDOCKET or in hard 

copy at the Air Docket in the EPA 

Docket Center, EPA/DC, EPA West, 

Room B102, 1301 Constitution Ave., 

NW, Washington, DC. The Public 

Reading Room is open from 8:30 a.m. to 

4:30 p.m., Monday through Friday, 

excluding legal holidays. The telephone 

number for the Public Reading Room is 

(202) 566–1744, and the telephone 

number for the Air Docket is (202) 566– 

1742. 

FOR FURTHER INFORMATION CONTACT: 

Carol Connell, Assessment and 

Standards Division, Office of 

Transportation and Air Quality, 

Environmental Protection Agency, 2000 

Traverwood Drive, Ann Arbor, MI 

48105; telephone number: (734) 214– 

4349; fax number: (734) 214–4050; email address: connell.carol@epa.gov, or 

Assessment and Standards Division 

Hotline; telephone number: (734) 214– 

4636; e-mail address: asdinfo@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Does This Action Apply To Me? 

This action may affect you if you 

produce or import new diesel engines 

which are intended for use in nonroad 

vehicles or equipment, such as 

agricultural and construction 

equipment, or if you produce or import 

such nonroad vehicles or equipment. It 

may also affect you if you convert 

nonroad vehicles or equipment, or the 

engines used in them, to use alternative 

fuels. It may also affect you if you 

produce, import, distribute, or sell 

nonroad diesel fuel. 

The following table gives some 

examples of entities that may have to 

follow the regulations. But because 

these are only examples, you should 

carefully examine the regulations in 40 

CFR parts 80, 89, 1039, 1065, and 1068. 

If you have questions, call the person 

listed in the FOR FURTHER INFORMATION 

CONTACT section of this preamble: 

Category NAICS 

codesa 

SIC 

codesb Examples of potentially regulated entities 

Industry ............................................. 333618 3519 Manufacturers of new nonroad diesel engines. 

Industry ............................................. 333111 3523 Manufacturers of farm machinery and equipment. 

Industry ............................................. 333112 3524 Manufacturers of lawn and garden tractors (home). 

Industry ............................................. 333924 3537 Manufacturers of industrial trucks. 

Industry ............................................. 333120 3531 Manufacturers of construction machinery. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38959 

Category NAICS 

codesa 

SIC 

codesb Examples of potentially regulated entities 

Industry ............................................. 333131 3532 Manufacturers of mining machinery and equipment. 

Industry ............................................. 333132 3533 Manufacturers of oil and gas field machinery and equipment. 

Industry ............................................. 811112 7533 Commercial importers of vehicles and vehicle components. 

811198 

Industry ............................................. 324110 2911 Petroleum refiners. 

Industry ............................................. 422710 5171 Diesel fuel marketers and distributors. 

422720 

Industry ............................................. 484220 4212 Diesel fuel carriers. 

484230 

7549 

5172 

4213 

Notes:


a North American Industry Classification System (NAICS). 


b Standard Industrial Classification (SIC) system code.


How Can I Get Copies of This Outline of This Preamble 

Document and Other Related I. Overview 

Information? A. What Is EPA Finalizing? 

B. Why Is EPA Taking This Action? Docket. EPA has established an II. Nonroad Engine Standards official public docket for this action A. What Are the New Engine Standards? under Docket ID No. OAR–2003–0012 at B. Are the New Standards Feasible? 

http://www.epa.gov/edocket. The C. Why Do We Need 15ppm Sulfur Diesel 


official public docket consists of the Fuel? 


documents specifically referenced in III. Requirements for Engine and Equipment 


this action, any public comments Manufacturers 


received, and other information related A. Averaging, Banking, and Trading 


to this action. Although a part of the B. Transition Provisions for Equipment 

Manufacturers official docket, the public docket does C. Engine and Equipment Small Business not include Confidential Business Provisions (SBREFA) Information (CBI) or other information D. Certification Fuel 


whose disclosure is restricted by statute. E. Temporary In-Use Compliance Margins 


The official public docket is the F. Test Cycles 


collection of materials that is available G. Other Test Procedure Issues 


for public viewing at the Air Docket in H. Engine Power 


the EPA Docket Center, (EPA/DC) EPA I. Auxiliary Emission Control Devices and 


Defeat Devices West, Room B102, 1301 Constitution J. Not-To-Exceed Requirements Ave., NW, Washington, DC. The EPA K. Investigating and Reporting Emission-
 Docket Center Public Reading Room is Related Defects 


open from 8:30 a.m. to 4:30 p.m., L. Compliance With the Phase-In 


Monday through Friday, excluding legal Provisions 


holidays. The telephone number for the M. Incentive Program for Early or Very 


Reading Room is (202) 566–1742, and Low Emission Engines 


the telephone number for the Air Docket N. Labeling and Notification Requirements 


is (202) 566–1742. O. General Compliance 

P. Other Issues Electronic Access. You may access Q. Highway Engines this Federal Register document R. Changes That Affect Other Engine
 electronically through the EPA Internet Categories
 under the ‘‘Federal Register’’ listings at IV. Our Program for Controlling Nonroad, 


http://www.epa.gov/fedrgstr/. Locomotive and Marine Diesel Fuel 

An electronic version of the public Sulfur 

docket is available through EPA’s A. Nonroad, Locomotive and Marine Diesel 

electronic public docket and comment Fuel Quality Standards 

system, EPA Dockets. You may use EPA B. Hardship Relief Provisions for 

Qualifying Refiners Dockets at http://www.epa.gov/edocket/ C. Special Provisions for Alaska and the to view public comments, access the Territories 

index listing of the contents of the D. NRLM Diesel Fuel Program Design official public docket, and to access E. How Are State Diesel Fuel Programs 

those documents in the public docket Affected by the Sulfur Diesel Program? 

that are available electronically. F. Technological Feasibility of the 500 and 

Although not all docket materials may 15 ppm Sulfur Diesel Fuel Program 

be available electronically, you may still G. What Are the Potential Impacts of the 

access any of the publicly available 15 ppm Sulfur Diesel Program on 

Lubricity and Other Fuel Properties? docket materials through the docket H. Refinery Air Permitting facility identified above. Once in the V. Nonroad, Locomotive and Marine Diesel system, select ‘‘search,’’ then key in the Fuel Program: Details of the Compliance appropriate docket identification and Enforcement Provisions

number. A. Special Fuel Provisions and Exemptions 

B. Additional Requirements for Refiners 

and Importers 

C. Requirements for Parties Downstream of 

the Refinery or Import Facility 

D. Diesel Fuel Sulfur Sampling and Testing 

Requirements 

E. Selection of the Marker for Heating Oil 

F. Fuel Marker Test Method 

G. Requirements for Record-keeping, 

Reporting, and PTDs 

H. Liability and Penalty Provisions for 

Noncompliance 

I. How Will Compliance With the Sulfur 

Standards Be Determined? 

VI. Program Costs and Benefits 

A. Refining and Distribution Costs 

B. Cost Savings to the Existing Fleet From 

the Use of Low Sulfur Fuel 

C. Engine and Equipment Cost Impacts 


D. Annual Costs and Cost Per Ton 


E. Do the Benefits Outweigh the Costs of 


the Standards? 

F. Economic Impact Analysis 

VII. Alternative Program Options Considered 

A. Summary of Alternatives 

B. Introduction of 15 ppm Nonroad Diesel 

Sulfur Fuel in One Step 

C. Applying the 15 ppm Sulfur Cap to 

Locomotive and Marine Diesel Fuel 

D. Other Alternatives 

VIII. Future Plans 

A. Technology Review 

B. Test Procedure Issues 

C. In-use Testing 


D. Engine Diagnostics 


E. Future NOX Standards for Engines in 


Mobile Machinery Over 750 hp 

F. Emission Standards for Locomotive and 

Marine Diesel Engines 

G. Retrofit Programs 

H. Reassess the Marker Specified for 

Heating Oil 

IX. Public Participation 

X. Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory 

Planning and Review 

B. Paperwork Reduction Act 

C. Regulatory Flexibility Act (RFA), as 

amended by the Small Business 

Regulatory Enforcement Fairness Act of 

1996 (SBREFA), 5 U.S.C. 601 et. seq 

D. Unfunded Mandates Reform Act 


E. Executive Order 13132: Federalism 


F. Executive Order 13175: Consultation 


and Coordination With Indian Tribal 

Governments 

G. Executive Order 13045: Protection of 

Children from Environmental Health and 

Safety Risks 
38960 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

I. National Technology Transfer 

Advancement Act 

J. Congressional Review Act 

XI. Statutory Provisions and Legal Authority 

I. Overview 

EPA today is completing the third 

recent major program to reduce 

emissions from the nation’s mobile 

sources. Today’s final rule establishes 

standards for nonroad diesel engines 

and fuel and builds on the recently 

adopted Tier 2 program for cars and 

light trucks and the 2007 highway diesel 

program for on-highway diesel engines. 

These three programs have in common 

large reductions in sulfur levels in fuel 

that will not only achieve public health 

benefits but also facilitate the 

introduction of advanced emissions 

control technologies. In 1996, emissions 

from land-based nonroad, marine, and 

locomotive diesel engines were 

estimated to be about 40 percent of the 

total mobile source inventory of PM2.5 

(particulate matter less than 2.5 microns 

in diameter) and 25 percent of the NOX 

(nitrogen oxides) inventory. Without 

today’s final rule, these contributions 

would be expected to grow to 44 percent 

and 47 percent by 2030 for PM2.5 and 

NOX, respectively. By themselves, landbased nonroad diesel engines are a very 

large part of the diesel mobile source 

PM2.5 inventory, contributing about 47 

percent in 1996, and growing to 70 

percent of this inventory by 2020 

without today’s final rule. In order to 

meet the Clean Air Act’s goal of 

cleaning up the nation’s air, emissions 

reductions from the nonroad sector are 

necessary. 

This program begins to get important 

emission reductions in 2008, and by 

2030 we estimate that this program will 

reduce over 129,000 tons PM2.5 and 

738,000 tons of NOX annually. These 

emission reductions will be directly 

helpful to the 474 counties nationwide 

that have been recently designated as 

nonattainment areas for the 8-hour 

ozone standard and for counties that 

will be designated as nonattainment for 

PM2.5 later this year. The resulting 

ambient PM2.5 and NOX reductions 

correspond to public health 

improvements in 2030 including 

approximately 12,000 fewer premature 

mortalities, 15,000 fewer heart attacks, 1 

million fewer lost days of work due to 

adults with respiratory symptoms, 5.9 

million fewer days when adults have to 

restrict their activities due to respiratory 

symptoms, and almost 6,000 emergency 

room visits for asthma attacks in 

children. Our projections in this final 

rule for public health and welfare 

improvements are greater than 

estimated at proposal. 

This final rule sets out emission 

standards for nonroad diesel engines— 

engines used mainly in construction, 

agricultural, industrial and mining 

operations—that will achieve reductions 

in PM and NOX emissions levels in 

excess of 95 percent and 90 percent 

respectively. This action also regulates 

nonroad diesel fuel for the first time by 

reducing sulfur levels in this fuel more 

than 99 percent to 15 parts per million 

(ppm). These provisions mirror those 

already in place for highway diesel 

engines, which will lead to the 

introduction of 15 ppm sulfur diesel 

fuel, followed by stringent engine 

standards in that sector beginning in 

2007 based on advanced aftertreatment 

technologies. We believe it is highly 

appropriate to bring the same types of 

expected advanced aftertreatment 

technologies to the nonroad market as 

soon as possible and we believe today’s 

nonroad fuel and engine program 

represents the next step in a feasible 

progression in the application of clean 

technologies to nonroad diesel engines 

and the associated diesel fuel. 

As we did with the proposed nonroad 

rulemaking, we followed specific 

principles when developing this final 

rule. First, the program achieves 

reductions in NOX, sulfur oxides (SOX), 

and PM emissions as early as possible. 

Second, it does so by implementing the 

fuel program as soon as possible while 

at the same time not interfering with the 

implementation and expected benefits 

of introducing ultra low sulfur fuel 

(diesel fuel containing no greater than 

15 ppm sulfur) in the highway market 

as required by the 2007 highway diesel 

rule. Next, we are generally treating 

vehicles and fuels as a system, that is 

promulgating engine and fuel standards 

in tandem in order to cost-effectively 

achieve the greatest emission 

reductions. Lastly, the program provides 

sufficient lead time to allow the 

migration of advanced emissions control 

technologies from the highway sector to 

nonroad diesel engines as well as the 

expansion of ultra low sulfur diesel fuel 

production to the nonroad market. 

The May 2003 proposed rulemaking 

culminated a multi-year effort to 

develop control strategies for nonroad 

engines. EPA worked collaboratively 

with stakeholders from industry, state 

and local government, and public health 

organizations in putting together its 

comprehensive (and widely praised) 

new engine standards and sulfur fuel 

controls. We received about 150,000 

comments on the proposal, almost all of 

them in support. We held three public 

hearings on the proposal and have 

participated in scores of meetings with 

commenters in developing the 

provisions of today’s final rule. An 

important aspect of this collaborative 

development effort has been EPA’s 

coordination with other governments in 

helping to further world harmonization 

of nonroad engine controls and fuel 

sulfur levels. Information gathered in 

these comments and discussions, taken 

in context with the principles described 

above, has been the basis for our action 

today. 

In summary, this rule sets out engine 

standards and emission test procedures 

(including not-to-exceed requirements) 

for new nonroad diesel engines, and 

sulfur control requirements for diesel 

fuel used in land-based nonroad, 

locomotive, and marine engines (NRLM 

fuel). Beginning in 2008, the new Tier 

4 engine standards for five power 

categories for engines from under 25 

horsepower (hp) to above 750 

horsepower will be phased in. New 

engine emissions test procedures will be 

phased in along with these new 

standards to better ensure emissions 

control over real-world engine operation 

and to help provide for effective 

compliance determination. The sulfur 

reductions to land-based nonroad diesel 

fuel will be accomplished in two steps, 

with an interim step from currently 

uncontrolled levels to a 500 ppm cap 

starting in June, 2007 and the final step 

to 15 ppm in June, 2010. This change in 

fuel quality will directly lead to 

important health and welfare benefits 

associated with the reduced generation 

of sulfate PM and SOX. Even more 

important, introduction of 15 ppm 

sulfur nonroad diesel fuel facilitates the 

introduction of advanced aftertreatment 

devices for nonroad engines. 

Although we did not propose to 

control locomotive and marine diesel 

fuel sulfur levels to 15 ppm in the 

NPRM, recognizing the important 

environmental and public welfare 

benefits that such a program could 

enable, we have decided to finalize this 

second step to 15 ppm sulfur fuel 

control program for locomotive and 

marine diesel fuel beginning in 2012. 

Locomotive and marine diesel fuel will 

first be reduced from current 

uncontrolled levels to a 500 ppm cap 

starting in June 2007 and the second 

step down to a 15 ppm cap will take 

place in June, 2012. While we have 

chosen to reduce sulfur levels in 

locomotive and marine diesel fuel to 15 

ppm in this rulemaking without 

adopting corresponding engine controls, 

we note that the Agency has already 

begun work to promulgate appropriate 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38961 

new standards for these engines.1 The 

monetized health and welfare benefits 

associated with further sulfur reduction 

to 15 ppm outweigh the costs of the 

sulfur reductions. Also, doing so now 

allows for the promulgation of a single 

integrated fuel program and provides 

the refining industry with long term 

predictability for sulfur control. 

The requirements in this rule will 

result in substantial benefits to public 

health and welfare and the environment 

through significant reductions in NOX 

and PM as well as nonmethane 

hydrocarbons (NMHC), carbon 

monoxide (CO), SOX, and air toxics. As 

noted, by 2030 this program will reduce 

annual emissions of NOX and PM by 

738,000 and 129,000 tons, respectively. 

We estimate these annual emission 

reductions will prevent 12,000 

premature deaths, over 8,900 

hospitalizations, 15,000 nonfatal heart 

attacks, and approximately 1 million 

days that people miss work because of 

respiratory symptoms, among 

quantifiable benefits. The overall 

quantifiable benefits will total $83 

billion annually by 2030 using a 3 

percent discount rate and $78 billion 

using a 7 percent discount rate at a cost 

of approximately $2 billion, with a 30-

year net present value for the benefits of 

$805 billion at 3 percent discounting 

and $352 billion at 7 percent 

discounting at a net present value cost 

of $27 billion at 3 percent discounting 

and $14 billion at 7 percent discounting. 

Clearly the benefits of this program 

dramatically outweigh its cost at a ratio 

of approximately 40:1 in 2030. 

A. What Is EPA Finalizing? 

As part of the proposed rulemaking, 

we set out very detailed provisions for 

new engine exhaust emission controls, 

sulfur limitations in nonroad and 

locomotive/marine diesel fuels, test 

procedures, compliance requirements, 

and other information. We also looked 

at a number of alternative program 

options, such as requiring refiners to 

reduce sulfur from uncontrolled levels 

to 15 ppm in one step in 2008. We 

continue to believe that the main 

program options set out in the proposal 

are feasible and the most cost-effective 

requirements, taking into account other 

factors such as lead time and interaction 

with the highway diesel program, so we 

are generally adopting the engine and 

fuel provisions which we proposed. 

1 EPA is issuing an Advanced Notice of Proposed 

Rulemaking for locomotive and marine engine 

standards as part of this effort. 

1. Nonroad Diesel Engine Emission 

Standards 

Today’s action adopts Tier 4 

standards for nonroad diesel engines of 

all horsepower ratings. These standards 

are technology-neutral in the sense that 

manufacturers are the responsible party 

in determining which emission control 

technologies will be needed to meet the 

requirements. Applicable emissions 

standards are determined by model year 

for each of five engine power band 

categories. For engines less than 25 hp, 

we are adopting a new engine standard 

for PM of 0.30 g/bhp-hr (grams per 

brake-horsepower-hour) beginning in 

2008, and leaving the previously-set 5.6 

g/bhp-hr combined standard for 

NMHC+NOX in place. For engines of 25 

to 75 hp, we are adopting standards 

reflecting approximately 50 percent 

reductions in PM control from today’s 

engines, again applicable beginning in 

2008. Then, starting in 2013, standards 

of 0.02 g/bhp-hr for PM and 3.5 g/bhphr for NMHC+NOX will apply for this 

power category. For engines of 75 to 175 

hp, the standards will be 0.01 g/bhp-hr 

for PM, 0.30 g/bhp-hr for NOX and 0.14 

g/bhp-hr for NMHC starting in 2012, 

with the NOX and NMHC standards 

phased in over a period of three to four 

years in order to address lead time, 

workload, and feasibility 

considerations. These same standards 

will apply to engines of 175 to 750 hp 

as well starting in 2011, with a similar 

phase-in. These PM, NOX, and NMHC 

standards and phase-in schedules are 

similar in stringency to the 2007 

highway diesel standards and are 

expected to require the use of highefficiency aftertreatment systems to 

ensure compliance. 

For engines above 750 hp, we are 

requiring PM and NMHC control to 

0.075 g/bhp-hr and 0.30 g/bhp-hr, 

respectively, starting in 2011. More 

stringent standards take effect in 2015 

with PM standards of 0.02 g/bhp-hr (for 

engines used in generator sets) and 0.03 

g/bhp-hr (for non-generator set engines), 

and an NMHC standard of 0.14 g/bhphr. The NOX standard in 2011 will be 

0.50 g/bhp-hr for generator set engines 

above 1200 hp, and 2.6 g/bhp-hr for all 

other engines in the above 750 hp 

category. This application of advanced 

NOX emission control technologies to 

generator set engines above 1200 hp will 

provide substantial NOX reductions and 

will occur earlier than we had proposed 

in the NPRM. In 2015, the 750–1200 hp 

generator set engines will be added to 

the stringent 0.50 g/bhp-hr NOX 

requirement as well. The long-term NOX 

standard for engines not used in 

generator sets (mobile machinery) will 

be addressed in a future action (we are 

currently considering such an action in 

the 2007 time frame). 

We are also continuing the averaging, 

banking, and trading provisions engine 

manufacturers can use to demonstrate 

compliance with the standards. We also 

are continuing provisions providing 

flexibilities which equipment 

manufacturers may use to facilitate 

transition to compliance with the new 

standards. In addition, we are including 

turbocharged diesels in the existing 

regulation of crankcase emissions, 

effective in the same year that the new 

standards first apply in each power 

category. 

As discussed at length in the 

proposal, new test procedures and 

compliance provisions, especially the 

not-to-exceed and transient tests, are 

necessary to ensure the benefits of the 

standards being adopted today are 

achieved when the aftertreatment-based 

standards go into place. We are 

therefore adopting the proposed test 

procedures and compliance provisions, 

with slight modifications designed to 

better implement the provisions, in 

today’s rule. We continue to believe the 

new transient test, cold start transient 

test, and not-to-exceed test procedures 

and standards will all help achieve our 

goal of emissions reductions being 

achieved in actual engine operation. 

As noted, the final rule also 

continues, and in some cases modifies, 

existing provisions that will facilitate 

the transition to the new engine and fuel 

standards. Many of these provisions will 

help small business engine and 

equipment manufacturers meet the 

requirements. They will also aid 

manufacturers in managing their 

development of engines and equipment 

that will meet our new standards. 

2. Nonroad, Locomotive, and Marine 

Diesel Fuel Quality Standards 

The fuel program requirements are 

very similar to those included in the 

proposal, with two notable exceptions. 

The first involves the standards 

themselves with the inclusion of 

locomotive and marine diesel fuel in the 

15 ppm standard. The second addresses 

the compliance provisions designed to 

ensure the effectiveness of the program. 

We are adopting the two-step 

approach to sulfur control, with all 

land-based nonroad, locomotive, and 

marine diesel fuel going from 

uncontrolled sulfur levels of 

approximately 3,000 ppm sulfur to 500 

ppm in June, 2007. The interim step 

will by itself achieve significant PM and 

SOX emission reductions with 

associated important health benefits as 

early as is practicable. Then, in June 
38962 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

2010, the sulfur cap for land-based 

nonroad engine diesel fuel will be 

reduced to the final standard of 15 ppm. 

Two years later, in 2012, the 15 ppm 

cap for locomotive and marine engine 

diesel fuel will go into effect. The 

reduction to 15 ppm sulfur provides 

additional direct control of PM and SOX 

emissions and is an enabling technology 

for the application of advanced catalystbased emission control technologies. 

Although we did not propose to 

control locomotive and marine diesel 

fuel to 15 ppm in the NPRM, after 

careful consideration and reviewing 

substantial comments from 

stakeholders, we have decided to 

include fuel used in locomotive and 

marine applications in the final step to 

15 ppm beginning in 2012. The 

incremental PM health and welfare 

benefits associated with this standard 

outweigh the costs. The locomotive and 

marine diesel fuel program provides a 

near-term positive impact on public 

health and welfare. Also, the 15 ppm 

sulfur diesel fuel provides an 

opportunity that may enable the 

application of advanced catalyst-based 

emission control technologies to 

locomotive and marine diesel engines. 

We are issuing an Advance Notice of 

Proposed Rulemaking for locomotive 

and marine diesel engines that 

investigates this potential. Recognizing 

the value that a locomotive and marine 

fuel program could have for public 

health and welfare, State and local 

authorities and public health advocacy 

organizations provided a large number 

of comments encouraging us to take 

action in this rulemaking to address 

emissions from this category. 

Including locomotive and marine fuel 

in the 15 ppm sulfur diesel fuel pool 

also simplifies the overall design of the 

fuel program and will simplify the 

distribution of diesel fuel. At the same 

time, we have finalized this standard 

with flexibilities designed specifically 

to address fuel program implementation 

issues raised in the comments. 

Noting that sulfur levels in highway 

diesel fuel will generally be at or below 

15 ppm starting in 2006 and not 

wanting to reduce the benefits of 

introducing this clean fuel, we spent 

considerable time developing a 

compliance assurance scheme for 

introducing our nonroad diesel sulfur 

program to mesh with the highway 

program requirements. We initially 

thought that a ‘‘baseline’’ approach 

essentially requiring refiners to 

maintain a constraint on sulfur levels of 

various distillate fuels, based on 

historical production volumes, was the 

most appropriate mechanism. 

Subsequently we learned that the other 

mechanism we discussed in the 

proposal, a ‘‘designate and track’’ type 

approach, is better suited to address our 

priorities and commitments for the 

nonroad diesel sulfur control program. 

This approach allows refiners to 

designate volumes of nonroad fuel into 

various categories and these 

designations would follow the fuel 

throughout the distribution system. We 

have successfully worked through our 

enforceability and other concerns with 

this approach and are now including it 

as our compliance mechanism for the 

fuel standards of today’s program. 

B. Why Is EPA Taking This Action? 

As we have discussed extensively in 

both the proposal and today’s action, 

EPA strongly believes it is appropriate 

to take steps now to reduce future 

emissions from nonroad, locomotive, 

and marine diesel engines. Emissions 

from these engines contribute greatly to 

a number of serious air pollution 

problems and would continue to do so 

in the future absent further reduction 

measures. Such emissions lead to 

adverse health and welfare effects 

associated with ozone, PM, NOX, SOX, 

and volatile organic compounds, 

including toxic compounds. In addition, 

diesel exhaust is of specific concern 

because it is likely to be carcinogenic to 

humans by inhalation as well as posing 

a hazard from noncancer respiratory 

effects. Ozone, NOX, and PM also cause 

significant public welfare harm such as 

damage to crops, eutrophication, 

regional haze, and soiling of building 

materials. 

Millions of Americans continue to 

live in areas with unhealthy air quality 

that may endanger public health and 

welfare. As discussed in more detail 

below, there are approximately 159 

million people living in areas that either 

do not meet the 8-hour ozone National 

Ambient Air Quality Standards 

(NAAQS) or contribute to violations in 

other counties as noted in EPA’s recent 

nonattainment designations for part or 

all of 474 counties. In addition, 

approximately 65 million people live in 

counties where air quality 

measurements violate the PM2.5 

NAAQS. These numbers do not include 

the tens of millions of people living in 

areas where there is a significant future 

risk of failing to maintain or achieve the 

ozone or PM2.5 NAAQS. Federal, state, 

and local governments are working to 

bring ozone and PM levels into 

compliance with the NAAQS attainment 

and maintenance plans and the 

reductions included in today’s rule will 

play a critical part in these actions. 

Reducing regional emissions of SOX is 

critical to this strategy for attaining the 

PM NAAQS and meeting regional haze 

goals in our treasured national parks. 

SOX levels can themselves pose a 

respiratory hazard. 

Although controlling air pollution 

from nonroad diesel exhaust is 

challenging, we strongly believe it can 

be accomplished through the 

application of high-efficiency emissions 

control technologies. As discussed in 

much greater detail in section II, very 

large emission reductions (in excess of 

90 percent) are possible, especially 

through the use of catalytic emission 

control devices installed in the nonroad 

equipment’s exhaust system and 

integrated with the engine controls. To 

meet the standards being adopted today, 

application of such technologies for 

both PM and NOX control will be 

needed for most engines. Highefficiency PM exhaust emission control 

technology has been available for 

several years, and it is the same 

technology we expect to be applied to 

meet the PM standards for highway 

diesel engines in 2007. For NOX, we 

expect the same high-efficiency 

technologies being developed for the 

2007 highway diesel engine program 

will be used to meet our new nonroad 

requirements. All of these technologies 

are dependent on the 15 ppm maximum 

sulfur levels for nonroad diesel fuel 

being adopted today. The fuel control 

program being adopted today also yields 

significant and important reductions in 

SOX from these sources. 

1. Basis for Action Under the Clean Air 

Act 

Section 213 of the Clean Air Act (‘‘the 

Act’’ or CAA) gives us the authority to 

establish emissions standards for 

nonroad engines and vehicles. Section 

213(a)(3) authorizes the Administrator 

to set standards for NOX, volatile 

organic compounds (VOCs), and CO 

which ‘‘standards shall achieve the 

greatest degree of emission reduction 

achievable through the application of 

technology which the Administrator 

determines will be available for the 

engines or vehicles.’’ As part of this 

determination, the Administrator must 

give appropriate consideration to cost, 

lead time, noise, energy, and safety 

factors associated with the application 

of such technology. The standards 

adopted today for NOX implement this 

provision. Section 213(a)(4) authorizes 

the Administrator to establish standards 

to control emissions of pollutants (other 

than those covered by section 213(a)(3)) 

which ‘‘may reasonably be anticipated 

to endanger public health and welfare.’’ 

Here, the Administrator may promulgate 

regulations that are deemed appropriate 

for new nonroad vehicles and engines 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38963 

which cause or contribute to such air 

pollution, taking into account costs, 

noise, safety, and energy factors. EPA 

believes the new controls for PM in 

today’s rule are an appropriate exercise 

of EPA’s discretion under the authority 

of section 213(a)(4). 

We believe the evidence provided in 

section II of this preamble and in the 

Regulatory Impact Analysis (RIA) 

indicates that the stringent emission 

standards adopted today are feasible 

and reflect the greatest degree of 

emission reduction achievable in the 

model years to which they apply. We 

have given appropriate consideration to 

costs in promulgating these standards. 

Our review of the costs and costeffectiveness of these standards indicate 

that they will be reasonable and 

comparable to the cost-effectiveness of 

other emission reduction strategies for 

the same pollutants that have been 

required or could be required in the 

future. We have also reviewed and given 

appropriate consideration to the energy 

factors of this rule in terms of fuel 

efficiency and effects on diesel fuel 

supply, production, and distribution, as 

discussed below, as well as any safety 

factors associated with these new 

standards. 

The information in this section and 

chapters 2 and 3 of the RIA regarding air 

quality and the contribution of nonroad, 

locomotive, and marine diesel engines 

to air pollution provides strong 

evidence that emissions from such 

engines significantly and adversely 

impact public health or welfare. First, as 

noted earlier, there is a significant risk 

that several areas will fail to attain or 

maintain compliance with the NAAQS 

for 8-hour ozone concentrations or the 

NAAQS for PM2.5 during the period that 

these new vehicle and engine standards 

will be phased into the vehicle 

population, and that nonroad, 

locomotive, and marine diesel engines 

contribute to such concentrations, as 

well as to concentrations of other 

criteria pollutants. This risk will be 

significantly reduced by the standards 

adopted today, as also noted above. 

However, the evidence indicates that 

some risk remains even after the 

reductions achieved by these new 

controls on nonroad diesel engines and 

nonroad, locomotive, and marine diesel 

fuel. Second, EPA believes that diesel 

exhaust is likely to be carcinogenic to 

humans. The risk associated with 

exposure to diesel exhaust includes the 

particulate and gaseous components 

among which are benzene, 

formaldehyde, acetaldehyde, acrolein, 

and 1,3–butadiene, all of which are 

known or suspected human or animal 

carcinogens, or have noncancer health 

effects. Moreover, these compounds 

have the potential to cause health effects 

at environmental levels of exposure. 

Third, emissions from nonroad diesel 

engines (including locomotive and 

marine diesel engines) contribute to 

regional haze and impaired visibility 

across the nation, as well as to odor, 

acid deposition, polycyclic organic 

matter (POM) deposition, 

eutrophication and nitrification, all of 

which are serious environmental 

welfare problems. 

EPA has already found in previous 

rules that emissions from new nonroad 

diesel engines contribute to ozone and 

CO concentrations in more than one 

area which has failed to attain the ozone 

and CO NAAQS (59 FR 31306, June 17, 

1994). EPA has also previously 

determined that it is appropriate to 

establish standards for PM from new 

nonroad diesel engines under section 

213(a)(4), and the additional 

information on diesel exhaust 

carcinogenicity noted above reinforces 

this finding. In addition, we have 

already found that emissions from 

nonroad engines significantly contribute 

to air pollution that may reasonably be 

anticipated to endanger public welfare 

due to regional haze and visibility 

impairment (67 FR 68242–68243, Nov. 

8, 2002). We find here, based on the 

information in this section of the 

preamble and chapters 2 and 3 of the 

RIA, that emissions from the new 

nonroad diesel engines covered by this 

final action likewise contribute to 

regional haze and to visibility 

impairment that may reasonably be 

anticipated to endanger public welfare. 

Taken together, these findings indicate 

the appropriateness of the nonroad 

diesel engine standards adopted today 

for purposes of section 213(a)(3) and (4) 

of the Act. These findings were 

unchallenged by commenters. 

These standards must take effect at 

‘‘the earliest possible date considering 

the lead time necessary to permit 

development and application of the 

requisite technology,’’ giving 

‘‘appropriate consideration’’ to cost, 

energy, and safety.2 The compliance 

dates we are adopting reflect careful 

consideration of these factors. The 

averaging, banking, and trading (ABT), 

equipment manufacturer flexibilities, 

and phase-in provisions for NOX are 

elements in our determination that we 

have selected appropriate lead times for 

the standards. 

Section 211(c) of the CAA allows us 

to regulate fuels where emission 

products of the fuel either: (1) Cause or 

contribute to air pollution that 

2 See Clean Air Act section 213(b). 

reasonably may be anticipated to 

endanger public health or welfare, or (2) 

will impair to a significant degree the 

performance of any emission control 

device or system which is in general 

use, or which the Administrator finds 

has been developed to a point where in 

a reasonable time it will be in general 

use were such a regulation to be 

promulgated. This rule meets both of 

these criteria. Sulfur dioxide (SO2)and 

sulfate PM emissions from nonroad, 

locomotive, marine and diesel vehicles 

are due to sulfur in diesel fuel. As 

discussed above, emissions of these 

pollutants cause or contribute to 

ambient levels of air pollution that 

endanger public health and welfare. 

Control of sulfur to 15 ppm for this fuel 

through a two-step program would lead 

to significant, cost-effective reductions 

in emissions of these pollutants. Control 

of sulfur to 15 ppm in nonroad diesel 

fuel will also enable emissions control 

technology that will achieve significant, 

cost-effective reduction in emissions of 

these pollutants, as discussed in section 

I.B.2 below. The substantial adverse 

effect of high sulfur levels on the 

performance of diesel emission control 

devices or systems that would be 

expected to be used to meet the nonroad 

standards is discussed in detail in 

section II. Control of sulfur to 15 ppm 

for locomotive and marine diesel fuel, 

as with nonroad diesel fuel, will 

provide meaningful additional benefits 

that outweigh the costs. In addition, our 

authority under section 211(c) is 

discussed in more detail in Appendix A 

to chapter 5 of the RIA. 

2. What Is the Air Quality Impact of 

This Final Rule? 

a. Public Health and Environmental 

Impacts 

With this rulemaking, we are acting to 

extend advanced emission controls to 

another major source of diesel engine 

emissions: Nonroad land-based diesel 

engines. This final rule sets out 

emission standards for nonroad landbased diesel engines—engines used 

mainly in construction, agricultural, 

industrial and mining operations—that 

will achieve reductions in PM and NOX 

standards in excess of 95 percent and 90 

percent, respectively for this class of 

vehicles. This action also regulates 

nonroad diesel fuel for the first time by 

reducing sulfur levels in this fuel more 

than 99 percent to 15 ppm. The diesel 

fuel sulfur requirements will decrease 

PM and SO2 emissions for land-based 

diesel engines, as well as for three other 

nonroad source categories: Commercial 

marine diesel vessels, locomotives, and 

recreational marine diesel engines. 
38964 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

These sources are significant 

contributors to atmospheric pollution of 

(among other pollutants) PM, ozone and 

a variety of toxic air pollutants. In 1996, 

emissions from these four source 

categories were estimated to be 40 

percent of the mobile source inventory 

for PM2.5 and 25 percent for NOX, and 

10 percent and 13 percent of overall 

emissions for these potential health 

hazards, respectively. Without further 

controls beyond those we have already 

adopted, these sources will emit 44 

percent of PM2.5 from mobile sources 

and 47 percent of NOX emissions from 

mobile sources by the year 2030. 

Nonroad engines, and most 

importantly nonroad diesel engines, 

contribute significantly to ambient 

PM2.5 levels, largely through direct 

emissions of carbonaceous and sulfate 

particles in the fine (and even ultrafine) 

size range. Nonroad diesels also 

currently emit high levels of NOX which 

react in the atmosphere to form 

secondary PM2.5 (namely ammonium 

nitrate) as well as ozone. Nonroad 

diesels also emit SO2 and hydrocarbons 

which react in the atmosphere to form 

secondary PM2.5 (namely sulfates and 

organic carbonaceous PM2.5). This 

section summarizes key points 

regarding the nonroad diesel engine 

contribution to these pollutants and 

their impacts on human health and the 

environment. EPA notes that we are 

relying not only on the information 

presented in this preamble, but also on 

the more detailed information in 

chapters 2 and 3 of the RIA and 

technical support documents, as well as 

information in the preamble, RIA, and 

support documents for the proposed 

rule. 

When fully implemented, this final 

rule will reduce nonroad (equipment 

such as construction, agricultural, and 

industrial), diesel PM2.5 and NOX 

emissions by 95 percent and 90 percent, 

respectively. It will also virtually 

eliminate nonroad diesel SO2 emissions, 

which amounted to approximately 

234,000 tons in 1996, and would 

otherwise grow to approximately 

326,000 tons by 2020. These dramatic 

reductions in nonroad emissions are a 

critical part of the effort by federal, state 

and local governments to reduce the 

health related impacts of air pollution 

and to reach attainment of the NAAQS 

for PM and ozone, as well as to improve 

other environmental effects such as 

atmospheric visibility. Based on the 

most recent data available for this rule, 

such problems are widespread in the 

United States. There are almost 65 

million people living in 120 counties 

with monitored PM2.5 levels (2000– 

2002) exceeding the PM2.5 NAAQS, and 

159 million people living in areas 

recently designated as exceeding 8-hour 

ozone NAAQS. Figure I–1 illustrates the 

widespread nature of these problems. 

Shown in this figure are counties 

exceeding the PM2.5 NAAQS or 

designated for nonattainment with the 

8-hour ozone NAAQS plus mandatory 

Federal Class I areas, which have 

particular needs for reductions in 

atmospheric haze. 

Our air quality modeling also 

indicates that similar conditions are 

likely to continue to persist in the future 

in the absence of additional controls 

and that the emission reductions would 

assist areas with attainment and future 

maintenance of the PM and ozone 

NAAQS.3 For example, in 2020, based 

on emission controls currently adopted, 

we project that 66 million people will 

live in 79 counties with average PM2.5 

levels above 15 micrograms per cubic 

meter (ug/m3). In 2030, the number of 

people projected to live in areas 

exceeding the PM2.5 standard is 

expected to increase to 85 million in 

107 counties. An additional 24 million 

people are projected to live in counties 

within 10 percent of the standard in 

2020, which will increase to 64 million 

people in 2030. Furthermore, for ozone, 

in 2020, based on emission controls 

currently adopted, the number of 

counties violating the 8-hour ozone 

standard is expected to decrease to 30 

counties where 43 million people are 

projected to live. Thereafter, exposure to 

unhealthy levels of ozone is expected to 

begin to increase again. In 2030 the 

number of counties violating the 8-hour 

ozone NAAQS is projected to increase 

to 32 counties where 47 million people 

are projected to live. In addition, in 

2030, 82 counties where 44 million 

people are projected to live will be 

within 10 percent of violating the ozone 

8-hour NAAQS. 

BILLING CODE 6560–50–P 

3 Note this analysis does not include the effects 

of the proposed Rule to Reduce Interstate Transport 

of Fine Particulate Matter and Ozone (Interstate Air 

Quality Rule). 69 FR 4566 (January 30, 2004). See 

http://www.epa.gov/interstateairquality/rule.html. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38965 

EPA is still developing the 

implementation process for bringing the 

nation’s air into attainment with the 

PM2.5 and 8-hour ozone NAAQS. Based 

on section 172(a) provisions in the Act, 

designated areas will need to attain the 

PM2.5 NAAQS in the 2010 (based on 

2007–2009 air quality data) to 2015 

(based on 2012 to 2014 air quality data) 

time frame, and then be required to 

maintain the NAAQS thereafter. 

Similarly, we expect that most areas 

covered under subpart 1 and 2 will 

attain the ozone standard in the 2007 to 

2014 time frame, depending on an area’s 

classification and other factors, and then 

be required to maintain the NAAQS 

thereafter. 

Since the emission reductions 

expected from this final rule would 

begin in this same time frame, the 

projected reductions in nonroad 

emissions would be used by states in 

meeting the PM2.5 and ozone NAAQS. In 

their comments on the proposal, states 

told EPA that they need nonroad diesel 

engine reductions in order to be able to 

meet and maintain the PM2.5 and ozone 

NAAQS as well as to make progress 

toward visibility requirements.4 

4 The following are sample comments from states 

and state associations on the proposed rule, which 

corroborate that this rule is a critical element in 

States’ NAAQS attainment efforts. Fuller 

information can be found in the Summary and 

Analysis of Comments. 

—‘‘Unless emissions from nonroad diesels are 

sharply reduced, it is very likely that many areas 

of the country will be unable to attain and maintain 

health-based NAAQS for ozone and PM.’’ 

(STAPPA/ALAPCO) 

—‘‘Adoption of the proposed regulation * * * is 

necessary for the protection of public health in 

California and to comply with air quality standards 

* * * The need for 15 ppm sulfur diesel fuel 

cannot be overstated.’’ (California Air Resources 

Board) 

—‘‘The EPA’s proposed regulation is necessary if 

the West is to make reasonable progress towards 

improving visibility in our nation’s Class I areas.’’ 

(Western Regional Air Partnership (WRAP)) 

Furthermore, this action would ensure 

that nonroad diesel emissions will 

continue to decrease as the fleet turns 

over in the years beyond 2014; these 

reductions will be important for 

maintenance of the NAAQS following 

attainment. 

Scientific studies show ambient PM is 

associated with a series of adverse 

health effects. These health effects are 

discussed in detail in the EPA Criteria 

Document for PM as well as the draft 

updates of this document released in the 

—‘‘Attainment of the NAAQS for ozone and PM2.5 

is of immediate concern to the states in the 

northeast region.* * * Thus, programs * * * such 

as the proposed rule for nonroad diesel engines are 

essential.’’ (NESCAUM) 
38966 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

past year.5, 6 EPA’s ‘‘Health Assessment 

Document for Diesel Engine Exhaust,’’ 

(the ‘‘Diesel HAD’’) also reviews health 

effects information related to diesel 

exhaust as a whole including diesel PM, 

which is one component of ambient 

PM.7 In the Diesel HAD, we note that 

the particulate characteristics in the 

zone around nonroad diesel engines are 

likely to be substantially the same as 

published air quality measurements 

made along busy roadways. This 

conclusion supports the relevance of 

health effects associated with highway 

diesel engine-generated PM to nonroad 

applications. 

As described in these documents, 

health effects associated with short-term 

variation in ambient PM have been 

indicated by epidemiologic studies 

showing associations between exposure 

and increased hospital admissions for 

ischemic heart disease, heart failure, 

respiratory disease, including chronic 

obstructive pulmonary disease (COPD) 

and pneumonia. Short-term elevations 

in ambient PM have also been 

associated with increased cough, lower 

respiratory symptoms, and decrements 

in lung function. Additional studies 

have associated changes in heart rate 

and/or heart rhythm in addition to 

changes in blood characteristics with 

exposure to ambient PM. Short-term 

variations in ambient PM have also been 

associated with increases in total and 

cardiorespiratory mortality. Studies 

examining populations exposed to 

different levels of air pollution over a 

number of years, including the Harvard 

Six Cities Study and the American 

Cancer Society Study, suggest an 

association between long-term exposure 

to ambient PM2.5 and premature 

mortality, including deaths attributed to 

lung cancer.8, 9 Two studies further 

analyzing the Harvard Six Cities Study’s 

air quality data have also established a 

5 U.S. EPA (1996.) Air Quality Criteria for 

Particulate Matter—Volumes I, II, and III, EPA, 

Office of Research and Development. Report No. 

EPA/600/P–95/001a–cF. This material is available 

electronically at http://www.epa.gov/ttn/oarpg/ 

ticd.html. 

6 U.S. EPA (2003). Air Quality Criteria for 

Particulate Matter—Volumes I and II (Fourth 

External Review Draft) This material is available 

electronically at http://cfpub.epa.gov/ncea/cfm/ 

partmatt.cfm. 

7 U.S. EPA (2002). Health Assessment Document 

for Diesel Engine Exhaust. EPA/600/8–90/057F 

Office of Research and Development, Washington, 

DC. This document is available electronically at 

http://cfpub.epa.gov/ncea/cfm/ 

recordisplay.cfm?deid=29060. 

8 Dockery, DW; Pope, CA, III; Xu, X; et al. (1993) 

An association between air pollution and mortality 

in six U.S. cities. N Engl J Med 329:1753–1759. 

9 Pope, CA, III; Burnett, RT; Calle, EE; et al. (2002) 

Lung cancer, cardiopulmonary mortality, and longterm exposure to fine particulate air pollution. 

JAMA 287: 1132–1141. 

specific influence of mobile sourcerelated PM2.5 on daily mortality and a 

concentration-response function for 

mobile source-associated PM2.5 and 

daily mortality. Another recent study in 

14 U.S. cities examining the effect of 

PM10 (particulate matter less than 10 

microns in diameter) on daily hospital 

admissions for cardiovascular disease 

found that the effect of PM10 was 

significantly greater in areas with a 

larger proportion of PM10 coming from 

motor vehicles, indicating that PM10 

from these sources may have a greater 

effect on the toxicity of ambient PM10 

when compared with other sources.10 

Of particular relevance to this rule is 

a recent cohort study which examined 

the association between mortality and 

residential proximity to major roads in 

the Netherlands. Examining a cohort of 

55 to 69 year-olds from 1986 to 1994, 

the study indicated that long-term 

residence near major roads, an index of 

exposure to primary mobile source 

emissions (including diesel exhaust), 

was significantly associated with 

increased cardiopulmonary mortality.11 

Other studies have shown children 

living near roads with high truck traffic 

density have decreased lung function 

and greater prevalence of lower 

respiratory symptoms compared to 

children living on other roads.12 A 

recent review of epidemiologic studies 

examining associations between asthma 

and roadway proximity concluded that 

some coherence was evident in the 

literature, indicating that asthma, lung 

function decrement, respiratory 

symptoms, and other respiratory 

problems appear to occur more 

frequently in people living near busy 

roads.13 As discussed later, nonroad 

diesel engine emissions, especially 

particulate, are similar in composition 

to those from highway diesel vehicles. 

Although difficult to associate directly 

with PM2.5, these studies indicate that 

direct emissions from mobile sources, 

and diesel engines specifically, may 

explain a portion of respiratory health 

10 Janssen, NA; Schwartz J; Zanobetti A; et al. 

(2002) Air conditioning and source-specific 

particles as modifiers of the effect of PM10 on 

hospital admissions for heart and lung disease. 

Environ Health Perspect 110(1):43–49. 

11 Hoek, G; Brunekreef, B; Goldbohm, S; et al. 

(2002) Association between mortality and 

indicators of traffic-related air pollution in the 

Netherlands: a cohort study. Lancet 

360(9341):1203–1209. 

12 Brunekreef, B; Janssen NA; de Hartog, J; et al. 

(1997) Air pollution from traffic and lung function 

in children living near motor ways. Epidemiology 

(8): 298–303. 

13 Delfino RJ. (2002) Epidemiologic evidence for 

asthma and exposure to air toxics: linkages between 

occupational, indoor, and community air pollution 

research. Env Health Perspect Suppl 110(4): 573– 

589. 

effects observed in larger-scale 

epidemiologic studies. Recent studies 

conducted in Los Angeles have 

illustrated that a substantial increase in 

the concentration of ultrafine particles 

is evident in locations near roadways, 

indicating substantial differences in the 

nature of PM immediately near mobile 

source emissions.14 For additional 

information on health effects, see the 

RIA. 

In addition to its contribution to 

ambient PM concentrations, diesel 

exhaust is of specific concern because it 

has been judged to pose a lung cancer 

hazard for humans as well as a hazard 

from noncancer respiratory effects. In 

this context, diesel exhaust PM is 

generally used as a surrogate measure 

for diesel exhaust. Further, nonroad 

diesel engine emissions also contain 

several substances known or suspected 

as human or animal carcinogens, or that 

have noncancer health effects as 

described in the Diesel HAD. Moreover, 

these compounds have the potential to 

cause health effects at environmental 

levels of exposure. These other 

compounds include benzene, 1,3-

butadiene, formaldehyde, acetaldehyde, 

acrolein, dioxin, and POM. For some of 

these pollutants, nonroad diesel engine 

emissions are believed to account for a 

significant proportion of total nationwide emissions. All of these compounds 

were identified as national or regional 

‘‘risk drivers’’ in the 1996 NATA.15 That 

is, these compounds pose a significant 

portion of the total inhalation cancer 

risk to a significant portion of the 

population. Mobile sources contribute 

significantly to total emissions of these 

air toxics. As discussed in more detail 

in the RIA, this final rulemaking will 

result in significant reductions of these 

emissions. 

In EPA’s Diesel HAD.16 diesel exhaust 

was classified as likely to be 

carcinogenic to humans by inhalation at 

environmental exposures, in accordance 

with the revised draft 1996/1999 EPA 

cancer guidelines. A number of other 

agencies (National Institute for 

Occupational Safety and Health, the 

International Agency for Research on 

Cancer, the World Health Organization, 

14 Yifang Zhu, William C. Hinds, Seongheon Kim, 

Si Shen and Constantinos Sioutas Zhu Y; Hinds 

WC; Kim S; et al. (2002) Study of ultrafine particles 

near a major highway with heavy-duty diesel traffic. 

Atmos Environ 36(27): 4323–4335. 

15 U.S. EPA (2002). National-Scale Air Toxics 

Assessment. This material is available 

electronically at http://www.epa.gov/ttn/atw/nata/. 

16 U.S. EPA (2002). Health Assessment Document 

for Diesel Engine Exhaust. EPA/600/8–90/057F 

Office of Research and Development, Washington 

DC. This document is available electronically at 

http://cfpub.epa.gov/ncea/cfm/ 

recordisplay.cfm?deid=29060. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38967 

California EPA, and the U.S. 

Department of Health and Human 

Services) have made similar 

classifications. 

EPA generally derives cancer unit risk 

estimates to calculate population risk 

more precisely from exposure to 

carcinogens. In the simplest terms, the 

cancer unit risk is the increased risk 

associated with average lifetime 

exposure of 1 ug/m3. EPA concluded in 

the Diesel HAD that it is not possible 

currently to calculate a cancer unit risk 

for diesel exhaust due to a variety of 

factors that limit the current studies, 

such as lack of an adequate doseresponse relationship between exposure 

and cancer incidence. 

However, in the absence of a cancer 

unit risk, the EPA Diesel HAD sought to 

provide additional insight into the 

significance of the cancer hazard by 

estimating possible ranges of risk that 

might be present in the population. The 

possible risk range analysis was 

developed by comparing a typical 

environmental exposure level for 

highway diesel sources to a selected 

range of occupational exposure levels 

and then proportionally scaling the 

occupationally observed risks according 

to the exposure ratios to obtain an 

estimate of the possible environmental 

risk. A number of calculations are 

needed to accomplish this, and these 

can be seen in the EPA Diesel HAD. The 

outcome was that environmental risks 

from diesel exhaust exposure could 

range from a low of 10¥4 to 10¥5 or be 

as high as 10¥3 this being a reflection 

of the range of occupational exposures 

that could be associated with the 

relative and absolute risk levels 

observed in the occupational studies. 

Because of uncertainties, the analysis 

acknowledged that the risks could be 

lower than 10¥4 or 10¥5 and a zero risk 

from diesel exhaust exposure was not 

ruled out. Although the above risk range 

is based on environmental exposure 

levels for highway mobile sources only, 

the 1996 NATA estimated exposure for 

nonroad diesel sources as well. Thus, 

the exposure estimates were somewhat 

higher than those used in the risk range 

analysis described above. The EPA 

Diesel HAD, therefore, stated that the 

NATA exposure estimates result in a 

similar risk perspective. 

The ozone precursor reductions 

expected as a result of this rule are also 

important because of health and welfare 

effects associated with ozone, as 

described in the Air Quality Criteria 

Document for Ozone and Other 

Photochemical Oxidants. Ozone can 

irritate the respiratory system, causing 

coughing, throat irritation, and/or 

uncomfortable sensation in the 

chest.17, 18 Ozone can reduce lung 

function and make it more difficult to 

breathe deeply, and breathing may 

become more rapid and shallow than 

normal, thereby limiting a person’s 

normal activity. Ozone also can 

aggravate asthma, leading to more 

asthma attacks that require a doctor’s 

attention and/or the use of additional 

medication. In addition, ozone can 

inflame and damage the lining of the 

lungs, which may lead to permanent 

changes in lung tissue, irreversible 

reductions in lung function, and a lower 

quality of life if the inflammation occurs 

repeatedly over a long time period 

(months, years, a lifetime). People who 

are of particular concern with respect to 

ozone exposures include children and 

adults who are active outdoors. Those 

people particularly susceptible to ozone 

effects are people with respiratory 

disease, such as asthma, and people 

with unusual sensitivity to ozone, and 

children. Beyond its human health 

effects, ozone has been shown to injure 

plants, which has the effect of reducing 

crop yields and reducing productivity in 

forest ecosystems.19, 20 

New research suggests additional 

serious health effects beyond those that 

were known when the 8-hour ozone 

health standard was set. Since 1997, 

over 1,700 new health and welfare 

studies relating to ozone have been 

published in peer-reviewed journals.21 

Many of these studies investigate the 

impact of ozone exposure on such 

health effects as changes in lung 

structure and biochemistry, 

inflammation of the lungs, exacerbation 

and causation of asthma, respiratory 

illness-related school absence, hospital 

and emergency room visits for asthma 

and other respiratory causes, and 

premature mortality. EPA is currently 

evaluating these and other studies as 

17 U.S. EPA (1996). Air Quality Criteria for Ozone 

and Related Photochemical Oxidants, EPA/600/P– 

93/004aF. Docket No. A–99–06. Document Nos. II– 

A–15 to 17. 

18 U.S. EPA (1996). Review of National Ambient 

Air Quality Standards for Ozone, Assessment of 

Scientific and Technical Information, OAQPS Staff 

Paper, EPA–452/R–96–007. Docket No. A–99–06. 

Document No. II–A–22. 

19 U.S. EPA (1996). Air Quality Criteria for Ozone 

and Related Photochemical Oxidants, EPA/600/P– 

93/004aF. Docket No. A–99–06. Document Nos. II– 

A–15 to 17. 

20 U.S. EPA (1996). Review of National Ambient 

Air Quality Standards for Ozone, Assessment of 

Scientific and Technical Information, OAQPS Staff 

Paper, EPA–452/R–96–007. Docket No. A–99–06. 

Document No. II–A–22. 

21 New Ozone Health and Environmental Effects 

References, Published Since Completion of the 

Previous Ozone AQCD, National Center for 

Environmental Assessment, Office of Research and 

Development, U.S. Environmental Protection 

Agency, Research Triangle Park, NC 27711 (7/2002) 

Docket No. A–2001–28, Document II–A–79. 

part of the ongoing review of the air 

quality criteria and NAAQS for ozone. 

A revised Air Quality Criteria Document 

for Ozone and Other Photochemical 

Oxidants will be prepared in 

consultation with EPA’s Clean Air 

Science Advisory Committee (CASAC). 

Key new health information falls into 

four general areas: Development of newonset asthma, hospital admissions for 

young children, school absence rate, 

and premature mortality. In all, the new 

studies that have become available since 

the 8-hour ozone standard was adopted 

in 1997 continue to demonstrate the 

harmful effects of ozone on public 

health and the need for areas with high 

ozone levels to attain and maintain the 

NAAQS. 

Finally, nonroad diesel emissions 

contribute to nine categories of nonhealth impacts: visibility impairment, 

soiling and material damage, acid 

deposition, eutrophication of water 

bodies, plant and ecosystem damage 

from ozone, water pollution resulting 

from deposition of toxic air pollutants 

with resulting effects on fish and 

wildlife, and odor. In particular, EPA 

determined that nonroad engines 

contribute significantly to unacceptable 

visibility conditions where people live, 

work and recreate, including 

contributing to visibility impairment in 

Federally mandated Class I areas that 

are given special emphasis in the Clean 

Air Act (67 FR 68242, November 8, 

2002). Visibility is impaired by fine PM 

and precursor emissions from nonroad 

diesel engines subject to this final rule. 

Reductions in emissions from this final 

rule will improve visibility as well as 

other environmental outcomes as 

described in the RIA. 

As supplementary information, we 

have made estimates using air quality 

modeling to illustrate the types of 

change in future PM2.5 and ozone levels 

that we would expect to result from a 

final rule like this as described in 

chapter 2 of the RIA. That modeling 

shows that control of nonroad emissions 

would produce nationwide air quality 

improvements in PM2.5 and ozone levels 

as well as visibility improvements. On 

a population-weighted basis, the average 

modeled change in future-year PM2.5 

annual averages is projected to decrease 

by 0.42 μg/m3 (3.3%) in 2020, and 0.59 

μg/m3 (0.6%) in 2030. In addition, the 

population-weighted average modeled 

change in future year design values for 

ozone would decrease by 1.8 parts per 

billion (ppb) in 2020, and 2.5 ppb in 

2030. Within areas predicted to violate 

the ozone NAAQS in the projected base 

case, the average decrease would be 

somewhat higher: 1.9 ppb in 2020 and 

3.0 ppb in 2030. 
38968 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

The PM air quality improvements 

expected from this final rule are 

anticipated to produce major benefits to 

human health and welfare, with a 

combined value in excess of half a 

trillion dollars between 2007 and 2030. 

For example, in 2030, we estimate that 

this program will reduce approximately 

129,000 tons PM2.5 and 738,000 tons of 

NOX. The resulting ambient PM 

reductions correspond to public health 

improvements in 2030, including 12,000 

fewer premature mortalities, 15,000 

fewer heart attacks, 200,000 fewer 

asthma exacerbations in children, and 1 

million fewer days when adults miss 

work due to their respiratory symptoms, 

and 5.9 million fewer days when adults 

have to restrict their activities due to 

respiratory symptoms. The reductions 

will also improve visibility and reduce 

diesel odor. For further details on the 

economic benefits of this rule, please 

refer to the benefit-cost discussion in 

section VI of this preamble and chapter 

9 of the RIA. 

b. Emissions From Nonroad Diesel 

Engines 

The engine and fuel standards in this 

final rule will affect emissions of direct 

PM2.5, SO2, NOX, VOCs, and air toxics 

for land-based nonroad diesel 

engines. 22 For locomotive, commercial 

marine vessel (CMV), and recreational 

marine vessel (RMV) engines, the final 

fuel standards will affect direct PM2.5 

and SO2 emissions. Each sub-section 

below discusses one of these 

pollutants,23 including expected 

emission reductions associated with the 

final standards.24 Table I.B–1 

summarizes the impacts of this rule for 

2020 and 2030. Further details on our 

inventory estimates, including results 

for other years, are available in chapter 

3 of the RIA. 

TABLE I.B–1.—ESTIMATED NATIONAL (50 STATE) REDUCTIONS IN EMISSIONS FROM NONROAD LAND-BASED, 

LOCOMOTIVE, COMMERCIAL MARINE, AND RECREATIONAL MARINE DIESEL ENGINES 

Pollutant [short tons] 2020 2030 

Direct PM2.5: 

PM2.5 Emissions Without Rule ................................................................................................................................. 167,000 181,000 

PM2.5 Emissions With 500 ppm Sulfur in 2007 and No Other Controls .................................................................. 144,000 155,000 

PM2.5 Emissions With 15 ppm Sulfur in 2012 and No Other Controls .................................................................... 141,000 152,000 

PM2.5 Emissions With Entire Rule ............................................................................................................................ 81,000 52,000 

PM2.5 Reductions Resulting from this Rule .............................................................................................................. 86,000 129,000 

SO2: 

SO2 Emissions Without Rule .................................................................................................................................... 326,000 379,000 

SO2 Emisions With 500 ppm Sulfur in 2007 ............................................................................................................ 37,000 43,000 

SO2 Emissions With Entire Rule (15 ppm Sulfur in 2012) ...................................................................................... 3,000 3,000 

SO2 Reductions Resulting from this Rule ................................................................................................................ 323,000 376,000 

NOX—Land-Based Nonroad Engines Onlya: 

NOX Emissions Without Rule ................................................................................................................................... 1,125,000 1,199,000 

NOX Emissions With Rule ........................................................................................................................................ 681,000 461,000 

NOX Reductions Resulting from this Rule ............................................................................................................... 444,000 738,000 

VOC—Land-Based Nonroad Engines Onlya: 

VOC Emissions Without Rule .................................................................................................................................. 98,000 97,000 

VOC Emissions With Rule ....................................................................................................................................... 75,000 63,000 

VOC Reductions Resulting from this Rule ............................................................................................................... 23,000 34,000 

Notes: 

a NOX and VOC numbers only include emissions for land-based nonroad diesel engines because the Tier 4 controls will not be applied to locomotive, commercial marine, and recreational marine engines; and no NOX and VOC emission reductions are generated through the lowering of 

fuel sulfur levels. 

i. Direct PM2.5 

As described earlier, the Agency 

believes that reductions of diesel PM2.5 

emissions are needed as part of the 

nation’s progress toward clean air. 

Direct PM2.5 emissions from land-based 

nonroad diesel engines amount to 

increasingly large percentages of total 

man-made diesel PM2.5. Between 1996 

and 2030, we estimate that the 

percentage of total man-made diesel 

PM2.5 emissions coming from landbased nonroad diesel engines will 

increase from about 46 percent to 72 

percent (based on a 48 state inventory). 

Emissions of direct PM2.5 from landbased nonroad diesel engines based on 

22 We are also adopting a few minor adjustments 

of a technical nature to current CO standards. 

Emissions effects from these standards are 

discussed in the RIA. 

23 The estimates of baseline emissions and 

emissions reductions from the final rule reported 

here for nonroad land-based, recreational marine, 

a 50 state inventory are shown in table 

I.B–1, along with our estimates of the 

reductions in 2020 and 2030 we expect 

would result from our final rule for a 

PM2.5 exhaust emission standard and 

from changes in the sulfur level in landbased nonroad, locomotive, and marine 

diesel fuel. Land-based nonroad, 

locomotive, and marine diesel fuel 

sulfur levels will be lowered to about 

340 ppm in-use (500 ppm maximum) in 

2007. Land-based nonroad diesel fuel 

sulfur will be lowered further to about 

11 ppm in-use (15 ppm maximum) in 

2010 and locomotive and marine diesel 

fuel sulfur will be lowered to the same 

level in 2012. In addition to PM2.5 

locomotive, and commercial marine vessel diesel 

engines are based on 50 state emissions inventory 

estimates. A 48 state inventory was used for air 

quality modeling that EPA conducted for this rule, 

of which Alaska and Hawaii are not a part. In cases 

where land-based nonroad diesel engine emissions 

are compared with non-mobile source portions of 

emissions estimates with the final rule, 

emissions estimates based on lowering 

diesel fuel sulfur without any other 

controls are shown in table I.B–1 for 

2020 and 2030. 

Figure I.B–1a shows our estimate of 

PM2.5 emissions between 2000 and 2030 

both without and with the final 

standards and fuel sulfur requirements 

of this rule. We estimate that PM2.5 

emissions from this source would be 

reduced by 71 percent in 2030. 

ii. SO2 

We estimate that land-based nonroad, 

CMV, RMV, and locomotive diesel 

engines emitted about 234,000 tons of 

the inventory, we use a 48 state emissions 

inventory, to match the 48 state nature of those 

other inventories. 

24 Please see the Summary and Analyses of 

Comments document for discussions of issues 

raised about the emission inventory estimates 

during the comment period for the NPRM. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38969 

SO2 in 1996, accounting for about 33 

percent of the SO2 from mobile sources 

(based on a 48 state inventory). With no 

reduction in diesel fuel sulfur levels, we 

estimate that these emissions will 

continue to increase, accounting for 

about 44 percent of mobile source SO2 

emissions by 2030. 

As part of this final rule, sulfur levels 

in fuel will be significantly reduced, 

leading to large reductions in nonroad, 

locomotive, and marine diesel SO2 

emissions. By 2007, the sulfur in diesel 

fuel used by all land-based nonroad, 

locomotive, and marine diesel engines 

will be reduced from the current average 

in-use level of between 2,300 to 2,400 

ppm 25 to an average in-use level of 

about 340 ppm, with a maximum level 

of 500 ppm. By 2010, the sulfur in 

diesel fuel used by land-based nonroad 

engines will be reduced to an average 

in-use level of 11 ppm with a maximum 

level of 15 ppm. Sulfur in diesel fuel 

used by locomotive and marine engines 

will be reduced to the same level by 

2012. Table II.B–1 and figure II.B–1b 

show the estimated reductions from 

these sulfur changes. 

25 Highway fuel is currently used in a significant 

fraction of land based nonroad equipment, 

locomotives, and marine vessels, reducing the inuse average sulfur level from about 3,000 ppm for 

uncontrolled high-sulfur fuel to 2,300 or 2,400 ppm. 

iii. NOX 

Table I.B–1 shows the 50 state 

estimated tonnage of NOX emissions for 

2020 and 2030 without the final rule 

and the estimated tonnage of emissions 

eliminated with the final rule in place. 

These results are shown graphically in 

Figure I.E–1c at the end of this section. 

We estimate that NOX emissions from 

these engines will be reduced by 62 

percent in 2030. 

We note that the magnitude of NOX 

reductions determined in the final rule 

analysis is somewhat less than what was 

reported in the proposal’s preamble and 

RIA, especially in the later years when 

the fleet has mostly turned over to Tier 

4 designs. The greater part of this is due 

to the fact that we have deferred setting 

a long-term NOX standard for mobile 

machinery over 750 horsepower to a 

later action. When this future action is 

completed, we would expect roughly 

equivalent reductions between the 

proposal and the overall final program, 

though there are some other effects 

reflected in the differing NOX 

reductions as well, due to updated 

modeling assumptions and the adjusted 

NOX standards levels for engines over 

750 horsepower. Section II.A.4 of this 

preamble contains a detailed discussion 

of the NOX standards we are adopting 

for engines over 750 horsepower as well 

as the basis for those standards. 

iv. VOCs and Air Toxics 

Based on a 48 state emissions 

inventory, we estimate that land-based 

nonroad diesel engines emitted over 221 

thousand tons of VOC in 1996. Between 

1996 and 2030, we estimate that landbased nonroad diesel engines will 

contribute about 2 to 3 percent of 

mobile source VOC emissions. Without 

further controls, land-based nonroad 

diesel engines will emit about 97 

thousand tons/year of VOC in 2020 and 

2030 nationally. 

Table I.B–1 shows our projection of 

the reductions in 2020 and 2030 for 

VOC emissions that we expect from 

implementing the final NMHC 

standards. This estimate is based on a 

50 state emissions inventory. By 2030, 

VOC emissions from this category 

would be reduced by 35 percent from 

baseline levels. 

While we are not adopting any 

specific gaseous air toxics standards in 

today’s rule, air toxics emissions would 

nonetheless be significantly reduced 

through the NMHC standards included 

in the final rule. By 2030, we estimate 

that emissions of air toxics pollutants, 

such as benzene, formaldehyde, 

acetaldehyde, 1,3-butadiene, and 

acrolein, would be reduced by 35 

percent from land-based nonroad diesel 

engines. Diesel PM reductions were 

discussed above. For specific air toxics 

reduction estimates, see chapter 3 of the 

RIA. 
38970 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

II. Nonroad Engine Standards and obtain very similar emissions Likewise, the long-term NOX standards 

In this section we describe the reductions. The long-term PM filter- we are adopting for nearly all engines 

emission standards for nonroad diesel based standards that apply to all engines above 75 hp will yield NOX reductions 

engines that we are setting to address over 25 hp, combined with the fuel of about 90% from the NOX levels 

the serious air quality problems change and new requirements to ensure expected from even the low-emitting 

discussed in section I. These Tier 4 robust control in the field, will yield PM Tier 3 engines due to first reach the 

standards, which take effect starting in reductions of over 95% from the in-use market in 2006 or later. The Tier 4 

2008, are very similar to those proposed, levels of today’s cleanest Tier 2 engines. standards will bring about large 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38971 

reductions in toxic hydrocarbon sulfur nonroad diesel fuel requirement A. What Are the New Engine Standards? 

emissions as well. 

In this final rule we are largely 

adopting the standards and timing we 

proposed, with the exception of those 

that apply to engines over 750 hp. We 

restructured and modified the standards 

and timing for these engines to address 

technical concerns and to focus on 

achieving comparable emission 

reductions through the introduction of 

advanced technology as early as feasible 

from specific applications within this 

power category. See section II.A.4 for a 

detailed discussion. We also are not 

adopting the proposed minor 

adjustments to the CO standard levels 

for some engines under 75 hp, as 

explained in section II.A.6. In addition, 

there are minor changes from the 

proposal in the phase-in approach we 

are adopting for NOX and NMHC 

standards, as detailed in this section. 

In this section we discuss: 

discussed in section IV); and 

• How diesel fuel sulfur affects an 

engine’s ability to meet the new 

standards. 

Additional provisions for engine and 

equipment manufacturers are discussed 

in detail in section III. These include: 

• The averaging, banking, and trading 

(ABT) program. 

• The transition program for 

equipment manufacturers. 

• The addition of a ‘‘not-to-exceed’’ 

program to ensure in-use emissions 

control. This program includes new 

emission standards and related test 

procedures to supplement the standards 

discussed in this section. 

• The test procedures and other 

compliance requirements associated 

with the emission standards. 

• Special provisions to aid small 

businesses in implementing our 

The Tier 4 exhaust emissions 

standards for PM, NOX, and NMHC are 

summarized in tables II.A–1, 2, and 4.26 

Crankcase emissions control 

requirements are discussed in section 

II.A.7. Previously adopted CO emission 

standards continue to apply as well. All 

of these standards apply to covered 

nonroad engines over the useful life 

periods specified in our regulations, 

except where temporary in-use 

compliance margins apply as discussed 

in section III.E. To help ensure that 

these emission reductions will be 

achieved in use, we have adopted test 

procedures for measuring compliance 

with these standards tailored to both 

steady-state and transient nonroad 

engine operating characteristics. These 

test procedures are discussed in several 

subsections of section III. Another 

component of our program to ensure 

• The Tier 4 engine standards, and requirements. control of emissions in-use is the new 

the schedule for implementing them; • An incentive program to encourage ‘‘not-to-exceed’’ (NTE) emission 

• The feasibility of the Tier 4 innovative technologies and the early standards and associated test 

standards (in conjunction with the low- introduction of new technologies. procedures, discussed in section III.J. 

TABLEII.A–1.—TIER4 PM STANDARDS(G/BHP-HR) ANDSCHEDULE

Engine power 

Model year 

2008 

hp < 25 (kW < 19)...................................................................................

a

0.30 ................................................................

25 ≤ hp < 75 (19 ≤ kW < 56)...................................................................

b

0.22................................................................0.02 

75 ≤ hp < 175 (56 ≤ kW < 130)...............................................................................................................................0.01................

175 ≤ hp ≤ 750 (130 ≤ kW ≤ 560)...........................................................................................................0.01................................

hp 750 (kW > 560)...................................................................................See table II.A–4 

2009 2010 2011 2012 2013 

................

Notes: 

a

For air-cooled, hand-startable, direct injection engines under 11 hp, a manufacturer may instead delay implementation until 2010 and dem-

onstrate compliance with a less stringent PM standard of 0.45 g/bhp-hr, subject also to additional provisions discussed in section II.A.3.a. b

A manufacturer has the option of skipping the 0.22 g/bhp-hr PM standard for all 50–75 hp engines. The 0.02 g/bhp-hr PM standard would 

then take effect one year earlier for all 50–75 hp engines, in 2012. 

TABLEII.A–2.—TIER4 NOX ANDNMHC STANDARDSANDSCHEDULE

Engine power 

Standard

(g/bhp-hr) 

Phase-in schedule

(model year)

(percent) 

NOX NMHC 2011 

25 ≤ hp < 75 (19 ≤ kW < 56)...................................................................3.5 NMHC+NOXa................................100% 

75 ≤ hp < 175 (56 ≤ kW < 130)...............................................................0.300.14

b50b50b100 

175 ≤ hp ≤ 750 (130 ≤ kW ≤ 560)...........................................................0.300.14505050100 

hp > 750 (kW > 560)...............................................................................See table II.A–4 

2012 2013 2014 

................

Notes: Percentages indicate production required to comply with the Tier 4 standards in the indicated model year. a

This is the existing Tier 3 combined NMHC+NOX standard level for the 50–75 hp engines in this category. In 2013 it applies to the 25–50 hp 

engines as well. b

Manufacturers may use banked Tier 2 NMHC+NOX credits from engines at or above 50 hp to demonstrate compliance with the 75–175 hp 

engine NOX standard in this model year. Alternatively, manufacturers may forego this special banked credit option and instead meet an alter-

native phase-in requirement of 25/25/25% in 2012, 2013, and 2014 through December 30, with 100% compliance required beginning December 

31, 2014. See sections III.A and II.A.2.b. 

26 Consistent with past EPA rulemakings for 

nonroad diesel engines, our regulations express 

standards, power ratings, and other quantities in 

international SI (metric) units—kilowatts, gram per 

kilowatt-hour, etc. This aids in achieving 

harmonization with standards-setting bodies 

outside the U.S., and in laboratory operations in 

which these units are the norm. However, in this 

preamble and in other rulemaking documents for 

the general reader, we have chosen to use terms 

more common in general usage in the U.S. Hence 

standards are expressed in units of grams per brake 

horsepower-hour, power ratings in horsepower, etc. 

In any compliance questions that might arise from 

differences in these due to, for example, rounding 

conventions, the regulations themselves establish 

the applicable requirements. 
38972 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

The long-term 0.01 and 0.02 g/bhp-hr 

Tier 4 PM standards for 75–750 hp and 

25–75 hp engines, respectively, 

combined with the fuel change and new 

requirements to ensure robust control in 

the field, represent a reduction of over 

95% from in-use levels expected with 

Tier 2/Tier 3 engines.27 The 0.30 g/bhphr Tier 4 NOX standard for 75–750 hp 

engines represents a NOX reduction of 

about 90% from in-use levels expected 

with Tier 3 engines. Emissions 

reductions from engines over 750 hp are 

discussed in section II.A.4. 

In general, there was widespread 

support in the comments for the 

proposed Tier 4 engine standards and 

for the timing we proposed for them. 

Some commenters raised categoryspecific concerns, especially for the 

smaller and the very large engine 

categories. These comments are 

discussed below. 

1. Standards Timing 

a. 2008 Standards 

The timing of the Tier 4 engine 

standards is closely tied to the timing of 

fuel quality changes discussed in 

section IV, in keeping with the systems 

approach we are taking for this program. 

The earliest Tier 4 engine standards take 

effect in model year 2008, in 

conjunction with the introduction of 

500 ppm maximum sulfur nonroad 

diesel fuel in mid-2007. This fuel 

change serves a dual environmental 

purpose. First, it provides a large 

immediate reduction in PM and SOX 

emissions for the existing fleet of 

engines in the field. Second, its 

widespread availability by the end of 

2007 aids engine designers in 

employing emissions controls capable of 

achieving the Tier 4 standards for model 

year 2008 and later engines; this is 

because the performance and durability 

of such technologies as exhaust gas 

recirculation (EGR) and diesel oxidation 

catalysts is improved by lower sulfur 

fuel.28 The reduction of sulfur in 

nonroad diesel fuel will also provide 

sizeable economic benefits to machine 

operators as it will reduce wear and 

corrosion and will allow them to extend 

oil change intervals (see section VI.B). 

These economic benefits will occur for 

all diesel engines using the new fuel, 

not just for those built in 2008 or later. 

27 Note that we are grouping all standards in this 

rule, including those that take effect in 2008, under 

the general designation of ‘‘Tier 4 standards.’’ As a 

result, there are no ‘‘Tier 3’’ standards in the multitier nonroad program for engines below 50 hp or 

above 750 hp. 

28 ‘‘Nonroad Diesel Emissions Standards Staff 

Technical Paper,’’ EPA420–R–01–052, October 

2001. 

As we proposed, these 2008 Tier 4 

engine standards apply only to engines 

below 75 hp. We are not setting Tier 4 

standards taking effect in 2008 for larger 

engines. The reasons for this differ 

depending on the engines’ hp rating. 

Setting Tier 4 2008 standards for 

engines at or above 100 hp would 

provide an insufficient period of 

stability (an element of lead time) 

between Tier 2⁄3 and Tier 4, and so 

would not be appropriate. This is 

because these engines become subject to 

existing Tier 2 or 3 NMHC+NOX 

standards in 2006 or 2007. Setting new 

2008 standards for them thus would 

provide only one or two years of Tier 2/ 

Tier 3 stability before another round of 

design changes would have to be made 

in 2008 for Tier 4. 

It is also inappropriate to establish 

2008 Tier 4 standards for engines of 75– 

100 hp. The stability issue just noted for 

larger engines is not present for these 

engines, because these engines are 

subject to Tier 3 NMHC+NOX standards 

starting in 2008, so that our setting a 

Tier 4 PM standard for them in the same 

year would not create the situation in 

which engines have to be redesigned 

twice to comply with new standards 

within a space of one or two years. 

However, EPA believes the more 

significant concern for these engines is 

meeting the stringent aftertreatmentbased standards for PM and NOX in 

2012. We are concerned that adopting 

interim 2008 standards for these engines 

would divert resources needed to 

achieve these 2012 standards and 

indeed jeopardize attaining them. Thus, 

although early emission reductions from 

these engines in 2008 would of course 

be desirable, we felt that the focus we 

are putting on obtaining much larger 

reductions from them in 2012, together 

with the fact that we already have a Tier 

3 NMHC+NOX standard taking effect for 

75–100 hp engines in 2008, warrants 

our not adding additional control 

requirements for these engines during 

this interim period. 

We note that the 50–75 hp engines 

also have a Tier 3 NMHC+NOX standard 

taking effect in 2008 and, as noted 

above, we are setting a new Tier 4 2008 

PM standard for them. Unlike the larger 

75–100 hp engines, however, the 50–75 

hp engines have one additional year, 

until 2013, before filter-based PM 

standards take effect, and also have no 

additional NOX control requirement 

being set beyond the 2008 Tier 3 

standard. These differences justify 

including the interim Tier 4 PM 

standard for these engines. We note too 

that achieving the 2008 PM standard is 

enabled in part by the large reduction in 

certification fuel sulfur that applies in 

2008 (see section III.D). Fuel sulfur has 

a known correlation to PM generation, 

even for engines without aftertreatment. 

Moreover, for any manufacturers who 

believe that accomplishing this PM pullahead will hamper their Tier 3 

compliance efforts for these engines, 

there is an alternative Tier 4 compliance 

option. Instead of meeting new Tier 4 

PM standards in both 2008 and 2013, 

manufacturers may skip the Tier 4 2008 

PM standard, and instead focus design 

efforts on introducing PM filters for 

these engines one year earlier, by 

complying with the aftertreatment-based 

standard for PM in 2012. These options 

are discussed in more detail in section 

II.A.3.b. 

We view the 2008 portion of the Tier 

4 program as highly important because 

it provides substantial PM and SOX 

emissions reductions during the several 

years prior to 2011. Initiating Tier 4 in 

2008 also fits well with the lead time 

(including stability), cost, and 

technology availability considerations of 

the overall program. Initiating the Tier 

4 engine standards in 2008 provides 

three to four years of stability after the 

start of Tier 2 for engines under 50 hp. 

As mentioned above, it also coincides 

with the start date of Tier 3 NMHC+NOX 

standards for 50–75 hp engines and so 

introduces no stability issues for these 

engines (as redesign for both PM and 

NOX occurs at the same time). The 2008 

start date provides almost 4 years of 

lead time to accomplish redesign and 

testing. The evolutionary character of 

the 2008 standards, based as they are on 

proven technologies, and the fact that 

some certified engines already meet 

these standards as discussed in section 

II.B, leads us to conclude that the 

standards are appropriate within the 

meaning of section 213(a)(4) of the 

Clean Air Act and that we are providing 

adequate lead time to achieve those 

standards. 

Engine and equipment manufacturers 

argued in their comments that the PM 

pull-ahead option for 50–75 hp engines 

is inappropriate because it constitutes a 

re-opening of the Tier 3 rule, involving 

as it does a Tier 4 PM standard in 2008, 

the same year that the Tier 3 

NMHC+NOX takes effect. They further 

argued that the non-pull-ahead option is 

not a real option because PM 

aftertreatment cannot be implemented 

for these engines in 2012. 

We disagree with both contentions. 

We determined, as part of our feasibility 

analysis for Tier 4, that it is feasible to 

design engines to meet the 2008 PM 

standard in the same year that a Tier 3 

NMHC+NOX standard takes effect. See 

section II.B and RIA sections 4.1.4 and 

4.1.5. One reason is that a substantial 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38973 

part of the 2008 PM emission reductions 

do not result from engine redesign, but 

rather are due to the reduction in 

certification test fuel maximum sulfur 

levels from 2000 to 500 ppm that results 

from the fuel change in the field. This 

reduction in sulfur levels also aids 

engine designers in employing emission 

control technologies that are 

detrimentally affected by sulfur, not 

only for PM control, but also for NMHC 

and NOX control. Examples of these 

sulfur-sensitive technologies are 

oxidation catalysts, which can 

substantially reduce PM and NMHC, 

and EGR, which is effective at reducing 

NOX. We note further that designing 

engines to meet the 2008 PM standard 

is also made less difficult by our not 

requiring engine designers to consider 

the transient test, cold start, and not-toexceed requirements that are otherwise 

part of the Tier 4 program. These 

requirements do not take effect for these 

engines until the 0.02 g/bhp-hr standard 

is implemented in 2012 or 2013. See 

section III.F for details. 

We also believe that the second 

option (compliance with the 

aftertreatment-based PM standard in 

2012, with no interim 2008 standard) is 

viable, and may be an attractive choice 

especially for engine families on the 

higher side of the 50–75 hp range that 

share a design platform with larger 

engines being equipped with PM filters 

to meet the Tier 4 standard for 75–175 

hp engines in 2012. We believe 75 hp 

is the appropriate cutpoint for setting 

and timing emissions standards (see 

section II.A.5), but it obviously is not a 

hard-and-fast separator between engine 

platforms for all manufacturers in all 

product lines. Even for many 50–75 hp 

engines that do not share a design 

platform with larger engines, we believe 

that a 2012 implementation date for PM 

filter technology may be practical, 

considering the 4-year lead time it 

affords after Tier 3 begins for these 

engines (in 2008), 8-year lead time after 

the last PM standard change (in 2004), 

and 5-year lead time after full-scale PM 

filter technology implementation on 

highway engines (in 2007). 

Engine manufacturers also 

commented that the two-options 

approach would cause their customers 

to switch engine suppliers in 2012 to get 

the least expensive engines possible in 

every year, thus compromising the 

environmental objectives and creating 

market disruptions. We have addressed 

these concerns as discussed in section 

II.A.3.b. 

b. 2011 and Later Standards 

The second fuel change for nonroad 

diesel fuel, to 15 ppm maximum sulfur 

in mid-2010, and the related engine 

standards for PM, NOX, and NMHC that 

begin to phase-in in the 2011 model 

year, provide most of the environmental 

benefits of the program. Like the 2008 

standards, these standards are timed to 

provide adequate lead time for engine 

and equipment manufacturers. They 

also are phased in over time to allow for 

the orderly transfer of technology from 

the highway sector, and to spread the 

overall workload for engine and 

equipment manufacturers engaged in 

redesigning a large number and variety 

of products for Tier 4. 

As we explained at proposal, we 

believe that the high-efficiency exhaust 

emission control technologies being 

developed to meet our 2007 emission 

standards for heavy-duty highway diesel 

engines can be adapted to most nonroad 

diesel applications. The engines for 

which we believe this adaptation from 

highway applications will be most 

straightforward are those in the 175–750 

hp power range, and thus these engines 

are subject to new standards requiring 

high-efficiency exhaust emission 

controls as soon as the 15 ppm sulfur 

diesel fuel is widely available, that is, in 

the 2011 model year. Engines of 75–175 

hp are subject to the new standards in 

the following model year, 2012, 

reflecting the need to spread the 

redesign workload and, to some extent, 

the greater effort that may be involved 

in adapting highway technologies to 

these engines. Engines between 25 and 

75 hp are subject to new standards for 

PM based on high-efficiency exhaust 

emission controls in 2013, reflecting 

again the need to spread the workload 

and the challenge of adapting this 

technology to these engines which 

typically do not have highway 

counterparts. Engines over 750 hp 

involve a number of special 

considerations, necessitating an 

implementation approach unique to 

these engines as explained in section 

II.A.4. Lastly , there are additional 

provisions discussed in sections III.B.2 

and III.M to encourage early technology 

introduction and to further draw from 

the highway technology experience. 

This approach of implementing Tier 4 

standards by power category over 2011– 

2013 provides for the orderly migration 

of technology and distribution of 

redesign workload over three model 

years, as EPA provided in Tier 3. 

Overall, this approach provides 4 to 6 

years of real world experience with the 

new technology in the highway sector, 

involving millions of engines (in 

addition to the several additional years 

provided by demonstration fleets on the 

road in earlier years), before the new 

standards take effect. We consider the 

implementation of Tier 4 standard start 

dates over 2011–2013 as described 

above to be responsive to the technology 

migration and workload distribution 

concerns. 

2. Phase-In of NOX and NMHC 

Standards for 75–750 hp Engines 

a. Percent-of-Production Phase-In for 

NOX and NMHC 

We are finalizing the percent-ofproduction phase-in for NOX and 

NMHC that we proposed for 75–750 hp 

engines. Because Tier 4 NOX emissions 

control technology is expected to be 

derived from technology first 

introduced in highway heavy-duty 

diesels, we proposed to adopt the 

implementation pattern for the Tier 4 

NOX standard which we adopted for the 

heavy-duty highway diesel program. 

This will help to ensure a focused, 

orderly development of robust highefficiency NOX control in the nonroad 

sector and will also help to ensure that 

manufacturers are able to take 

maximum advantage of the highway 

engine development program, with 

resulting cost savings. 

The heavy-duty highway rule allows 

for a gradual phase-in of the NOX and 

NMHC requirements over multiple 

model years: 50% of each 

manufacturer’s U.S.-directed production 

volume must meet the new standard in 

2007–2009, and 100% must do so by 

2010. Through the use of emissions 

averaging, this phase-in approach also 

provides the flexibility for highway 

engine manufacturers to meet that 

program’s environmental goals by 

allowing somewhat less-efficient NOX 

controls on more than 50% of their 

production during the 2007–2009 

phase-in years. 

We follow the same pattern in this 

rule. As proposed, we are phasing in the 

NOX standards for nonroad diesels over 

2011–2013 as indicated in table II.A–2, 

based on compliance with the Tier 4 

standards for 50% of a manufacturer’s 

U.S.-directed production in each power 

category between 75 and 750 hp in each 

phase-in model year. The phase-in of 

standards for engines over 750 hp is 

discussed in section II.A.4. With a NOX 

phase-in, all manufacturers are able to 

introduce their new technologies on a 

limited number of engines, thereby 

gaining valuable experience with the 

technology prior to implementing it on 

their entire product line. In tandem with 

the equipment manufacturer transition 

program discussed in section III.B, the 

phase-in ensures timely progress to the 

Tier 4 standard levels while providing 

a great degree of implementation 

flexibility for the industry. 
38974 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

This ‘‘percent of production phase-in’’ 

is intended to take maximum advantage 

of the highway program technology 

development. It adds a new dimension 

of implementation flexibility to the 

staggered ‘‘phase-in by power category’’ 

used in the nonroad program for Tiers 

1–3 (and also in this Tier 4) which, 

though structured to facilitate 

technology development and transfer, is 

more aimed at spreading the redesign 

workload. Because the Tier 4 program 

involves challenges in addressing both 

technology development and redesign 

workload, we believe that incorporating 

both of these phase-in mechanisms into 

the program is warranted, resulting in 

the coordinated phase-in plan shown in 

table II.A–2, which we are finalizing 

essentially as proposed. Note that this 

results in the new NOX requirements for 

75–175 hp engines taking effect starting 

in the second year of the 2011–2013 

general phase-in, in effect creating a 50– 

50% phase-in in 2012–2013 for this 

category. This then staggers the Tier 4 

start years by power category as in past 

tiers: 2011 for engines at or above 175 

hp, 2012 for 75–175 hp engines, and 

2013 for 25–75 hp engines (for which no 

NOX adsorber-based standard and thus 

no percentage phase-in is being 

adopted), while still providing a 

production-based phase-in for advanced 

NOX control technologies. 

Comments from the States and 

environmental organizations argued for 

the completion of the phase-in by the 

end of 2012, contending that technology 

progress for NOX control in the highway 

sector has been good to date and would 

support an accelerated phase-in in the 

nonroad sector. However, our 

assessment continues to show unique 

(though surmountable) challenges in 

adapting advanced technologies to 

nonroad engines, especially for engines 

least like highway diesels, and it is 

these engines that would be most 

affected by a truncated phase-in 

schedule. Furthermore, even if we were 

to conclude that advanced technologies 

will be ready earlier than expected, we 

would not be able to move up the start 

of phase-in dates because these dates 

also depend on low-sulfur fuel 

availability. Thus an end-of-2012 phasein completion date would result in 

phase-ins as short as one year, thus 

degrading the industry’s opportunity to 

distribute the redesign workload and 

departing from the pattern set by the 

highway program. Both of these are 

critical factors in our assessment that 

the proposed engine standards are 

feasible, and so a change to shorter 

phase-ins would jeopardize 

achievement of our environmental 

objectives for nonroad diesels. Therefore 

we are not adopting the suggested 

earlier completion of the phase-in. 

As proposed, we are phasing in the 

Tier 4 NMHC standard for 75–750 hp 

engines with the NOX standard, as is 

being done in the highway program. 

Engines certified to the new NOX 

requirement would be expected to 

certify to the NMHC standard as well. 

The ‘‘phase-out’’ engines (those not 

certified to the new Tier 4 NOX and 

NMHC standards) would continue to be 

certified to the applicable Tier 3 

NMHC+NOX standard. As discussed in 

section II.B, we believe that the NMHC 

standard is readily achievable through 

the application of PM traps to meet the 

PM standard, which does not involve 

such a phase-in. However, in the 

highway program we chose to phase in 

the NMHC standard with the NOX 

standard to simplify the phase-in under 

the percent-of-production approach 

taken there, thus avoiding subjecting the 

‘‘phase-out’’ engines to separate 

standards for NMHC and NMHC+NOX 

(which could lead to increased 

administrative costs with essentially no 

different environmental result). The 

same reasoning applies here because, as 

in the highway program, the previoustier standards are combined 

NMHC+NOX standards. No commenters 

objected to this approach. 

Because of the tremendous variety of 

engine sizes represented in the nonroad 

diesel sector, we are finalizing our 

proposed requirement that the phase-in 

requirement be met separately in both of 

the power categories with a phase-in 

(75–175 hp and 175–750 hp).29 For 

example, a manufacturer that produces 

1000 engines for the 2011 U.S. market 

in the 175 to 750 hp range would have 

to demonstrate compliance with the 

NOX and NMHC standards on at least 

500 of these engines, regardless of how 

many complying engines the 

manufacturer produces in the 75–175 

hp category. (Note however that we are 

allowing averaging of emissions 

between these engine categories through 

the use of power-weighted ABT program 

credits.) We believe that this restriction 

reflects the availability of emissions 

control technology, and is needed to 

avoid erosion of environmental benefits 

that might occur if a manufacturer with 

a diverse product offering were to meet 

the phase-in with relatively low cost 

smaller engines, thereby delaying 

29 Note exceptions to the percent phase-in 

requirements during the phase-in model years 

discussed in sections III.L and III.M. These deal 

with differences between a manufacturer’s actual 

and projected production levels, and with 

incentives for early or very low emission engine 

introductions. 

compliance on larger engines with 

much higher lifetime emissions 

potential. Even so, the horsepower 

ranges for these power categories are 

fairly broad, so this restriction allows 

ample freedom to manufacturers to 

structure compliance plans in the most 

cost-effective manner. There were no 

adverse comments on this approach. 

b. Special Considerations for the 75–175 

hp Category 

As discussed in the proposal, the 75– 

175 hp category of engines and 

equipment may involve added workload 

challenges for the industry to develop 

and transfer technology. Though 

spanning only 100 hp, this category 

represents a great diversity of 

applications, and comprises a 

disproportionate number of the total 

nonroad engine and machine models. 

Some of these engines, though having 

characteristics comparable to many 

highway engines such as turbocharging 

and electronic fuel control, are not 

directly derived from highway engine 

platforms and so are likely to require 

more development work than larger 

engines to transfer emission control 

technology from the highway sector. 

Furthermore, the engine and equipment 

manufacturers have greatly varying 

market profiles in this category, from 

focused one- or two-product offerings to 

very diverse product lines with a great 

many models. 

Therefore, in addition to the 

flexibility provided through the phasein mechanism, we proposed two 

optional measures to provide added 

flexibility in implementing the Tier 4 

NOX standards, while keeping a priority 

on bringing PM emissions control into 

this diverse power category as quickly 

as possible. First, we proposed to allow 

manufacturers to use NMHC+NOX 

credits generated by any Tier 2 engines 

over 50 hp (in addition to any other 

allowable credits) to demonstrate 

compliance with the Tier 4 requirement 

for 75–175 hp engines in 2012, 2013, 

and 2014 only. Second, we proposed 

allowing a manufacturer to instead 

demonstrate compliance with a reduced 

phase-in requirement of 25% for NOX 

and NMHC in each of 2012, 2013, and 

the first 9 months of 2014. Full 

compliance (100% phase-in) with the 

Tier 4 standards would have needed to 

be demonstrated beginning October 1, 

2014. 

Engine manufacturers reinforced the 

points we made in the proposal 

regarding added workload challenges 

for this diverse category of engines and 

machines. However, they suggested that 

the first of the proposed options to 

address these challenges (allowing use 
HR) 

Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38975 

of Tier 2 credits) is not likely to be used 

due to a lack of available Tier 2 credits, 

and therefore should be dropped, and 

that the second option (allowing a 

slower phase-in) provided too short a 

stability period, and should be modified 

to delay final compliance by an 

additional 3 months, to December 31, 

2014 or January 1, 2015. In addition to 

describing the very large redesign 

workload, they pointed out that engines 

and machines in this category typically 

do not have a model year that differs 

from the calendar year, and so the 

substantial changes required for Tier 4 

compliance in October 2014 could force 

the need to change the product for all 

of 2014, effectively shortening the 

phase-in to two years. One manufacturer 

argued that the compliance date for the 

75–100 hp engines in this category 

should be delayed an additional year, to 

2016, and that the start of the phase-in 

for these engines should be likewise 

delayed from 2012 to 2013. 

We do not feel that the first option 

(allowing use of Tier 2 credits) should 

be dropped, as it provides an alternative 

flexibility mechanism for a power 

category in which flexibility is clearly 

important, and is environmentally 

helpful as it provides an option for 

manufacturers to achieve NOX emission 

reductions earlier than under the second 

option. By providing an opportunity to 

use Tier 2 credits in the 75–175 hp 

category, it coordinates well with the 

Tier 2 credit use opportunity we are 

providing for the 50–75 hp engines 

meeting the 2008 PM standard (see 

section III.A), and allows for 

coordinated redesign and credit use 

planning by a manufacturer over this 

wide power range over many years. 

Nonetheless, recognizing that the 

second option may be more attractive to 

manufacturers, and considering the 

comments they provided on it, we have 

concluded that a three month phase-in 

extension until the end of 2014 is 

warranted to address the workload 

burden and to align product cycle dates. 

Thus we are adopting the December 31, 

2014 implementation date suggested in 

comments for completion of the 75–175 

hp engine phase-in. 

We do not agree that an additional 

year of delay is appropriate for the 75– 

100 hp engines in this category. The 

comment expressing interest in our 

doing so did not provide any basis for 

it in technological feasibility or in 

workload burden, and we do not see any 

basis for it ourselves. 

Therefore, we are adopting both of the 

proposed optional measures for the 75– 

175 hp engine phase-in, except that in 

the second option, full compliance 

(100% phase-in) with the Tier 4 

standards will need to be demonstrated 

beginning December 31, 2014. As 

proposed, manufacturers using this 

reduced phase-in option will not be 

allowed to generate NOX credits from 

engines in this power category in 2012, 

2013, and 2014, except for use in 

averaging within the 75–175 hp category 

(that is, no banking or trading, or 

averaging with engines in other power 

categories). We believe that this 

restriction on credit use is appropriate, 

considering that larger engine categories 

will be required to demonstrate a 

substantially greater degree of 

compliance with the 0.30 g/bhp-hr NOX 

standard several years earlier than 

engines built under this option. As the 

purpose of this option is to aid 

manufacturers in implementing Tier 4 

NOX standards for this challenging 

power category, we do not want any 

manufacturers who might be capable of 

building substantially greater numbers 

of cleaner engines to use this option as 

an easy and copious source of credits 

(owing to its slower phase-in of 

stringent standards) that in turn can be 

used to delay building clean engines in 

other categories or model years. 

c. Alternative Phase-In Standards 

To ensure that Tier 4 engine 

development is able to take maximum 

advantage of highway diesel technology 

advances, we proposed to adopt 

nonroad diesel provisions in the 

averaging, banking, and trading program 

that would parallel the heavy-duty 

highway engine program’s ‘‘split family 

provisions’’ (see 68 FR 28470, May 23, 

2003). In essence, these allow a 

manufacturer to declare an engine 

family during the phase-in years that is 

certified at NOX levels roughly midway 

between the phase-out standard and 

phase-in standard, without the 

complication of tracking credit 

generation and use. Because they 

constitute a calculational simplification 

of the emissions averaging provisions, 

these split family provisions do not 

result in a loss in environmental 

benefits compared to what the phase-in 

can achieve. 

The nonroad proposal also included 

specific emission levels for these split 

families, rather than just describing how 

they are calculated. Commenters 

suggested that we go one step further 

still and express these levels as 

alternative standards. They argued that 

this would facilitate attempts at 

harmonizing standards globally, 

especially for standards-setting bodies 

such as the European Commission that 

do not have emissions averaging 

programs. We are also aware that most 

manufacturers of highway diesel 

engines are now planning to comply 

with our 2007 standards using this 

emissions averaging approach, 

increasing the significance of comments 

on the topic from nonroad engine 

manufacturers, many of whom also 

make highway engines.30 

After carefully considering the issues 

involved, we agree that the proposed 

approach lends itself to expression in 

terms outside of the averaging, banking, 

and trading program and that it makes 

sense to do so. We are creating such an 

alternative in the final regulations 

accordingly. These alternative standards 

do not substantively change our Tier 4 

program from what we proposed, but 

rather respond to manufacturers’ 

suggestions for administrative 

simplifications to what is essentially an 

averaging-based flexibility option in 

demonstrating compliance with the 

percent-of-production NOX phase-in. 

The alternative NOX phase-in standards 

are shown in table II.A–3. They apply 

only during the NOX phase-in years. 

Manufacturers may use both approaches 

within a power category if desired, 

certifying some engines to the 

alternative standards, with the rest 

subject to the phase-in percentage 

requirement. Note that engines under 75 

hp subject to Tier 4 NOX standards do 

not have an alternative standard because 

they do not have a NOX phase-in, and 

engines over 750 hp do not have an 

alternative standard because of the 

separate standards we are adopting for 

these engines (explained in section 

II.A.4). 

TABLEII.A–3.—TIER4 ALTERNATIVE

NOX PHASE-IN

STANDARDS(G/BHP-

Engine power NOX standard

(g/bhp-hr) 

75 ≤ hp < 175 (56 ≤ kW < 

130).................................

a

1.7 

175 ≤ hp ≤ 750 (130 ≤ kW 

≤ 560)..............................1.5 

Notes: aUnder the option identified in foot-

note b of table II.A–2, by which manufacturers 

may meet an alternative phase-in requirement 

of 25/25/25% in 2012, 2013, and 2014 through 

December 30, the corresponding alternative 

NOX standard is 2.5 g/bhp-hr. 

The engines certified under these 

standards will of course also need to 

meet the Tier 4 PM and crankcase 

control requirements that take effect for 

all engines in the first phase-in year. 

They will also need to comply with all 

Tier 4 provisions that would apply to 

30 See the recently published ‘‘Highway Diesel 

Progress Review Report 2,’’ EPA420–R–04–004, 

available at http://www.epa.gov/otaq/ 

diesel.htm#progreport2. 
38976 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

phase-in engines, including the 0.14 g/ 

bhp-hr NMHC standard and the NTE 

and transient test requirements for all 

pollutants. We recognize that this differs 

from what is required under the phasein approach, in which these 

requirements would not apply to the 

50% of engines categorized as ‘‘phaseout’’ engines. However, under the 

alternative standards approach, what 

would have been two different engine 

families (one meeting phase-in 

requirements and one meeting phaseout requirements, with NOX and PM 

emissions averaging allowed between 

them under the ABT provisions) are 

replaced by a single engine family 

meeting the one set of alternative 

standards. Therefore all of the engines 

in this family must by default meet the 

phase-in requirements for provisions 

that lack any sort of averaging 

mechanism (NMHC standard, NTE, etc). 

As a result, any manufacturer choosing 

to design to the alternative standards 

rather than using the phase-in approach 

provides some additional environmental 

benefit as an indirect result of choosing 

this approach. 

We also believe that this alternative 

standards provision makes appropriate a 

further adjustment to the NOX phase-in 

scheme to better preserve both the 

advanced technology phase-in 

approach, for those manufacturers 

choosing that compliance path, and the 

alternative standards approach, for 

those choosing that path. Under the 

proposal, the provision for certifying a 

split engine family at a pre-designated 

NOX level would not allow credit 

generation by or credit use on engines 

in the split family (other than for 

averaging within the family). This was 

consistent with our goal of providing a 

simple, single average NOX standard 

level for the family, equivalent to 

arbitrarily designating a portion of the 

engines in the family as ‘‘phase-out’’ 

engines (credit generators) and the rest 

as ‘‘phase-in’’ engines (credit users) 

with a net credit balance of zero, while 

avoiding the burden of actually 

calculating and tracking credits. This 

was also consistent with our approach 

under the 2007 highway engine program 

from which this concept is derived. 

However, because this split family 

provision has evolved into a set of 

alternative standards, there is no longer 

a need to prohibit the generation and 

use of ABT credits for these engines to 

preserve a de facto net zero credit 

balance, and so, considering that it is 

also not environmentally detrimental, 

we believe it is appropriate to allow 

credit use and generation for these 

engines as for other engines. A 

consequence of doing so, consistent 

with all of our ABT programs, is the 

adoption of NOX FEL caps for these 

engines. To maintain the character of 

this compliance path as producing 

engines during the phase-in years that 

emit at NOX levels which are roughly 

averaged between Tier 3 and final Tier 

4 levels, we are setting NOX FEL caps 

for these engines at levels reasonably 

close to the alternative standards. (See 

section III.A for details.) Because we are 

also maintaining the original phase-in/ 

phase-out compliance path, a 

manufacturer wishing to build engines 

with NOX levels higher than these FEL 

caps, at or approaching the Tier 3 levels, 

could still do so; in fact these would in 

actuality fit the description of a phaseout engine. This manufacturer would 

also, of course, have to produce a 

corresponding number of phase-in 

engines meeting the aftertreatmentbased Tier 4 NOX standards. 

We also observe that the creation of 

alternative standards provides the 

opportunity to adjust the phase-in/ 

phase-out provisions so as to reinforce 

their focus on introducing highefficiency NOX aftertreatment 

technology during the phase-in years, 

which is, of course, their aim. We are 

doing this by setting NOX family 

emission limit (FEL) caps for phase-in 

engines at the same low levels as for 

Tier 4 engines produced in the postphase-in years. (Again, see section III.A 

for details.) Although the engine 

manufacturers indicated in their 

comments that they did not believe it 

likely that anyone would choose this 

phase-in/phase-out compliance path, we 

believe that preserving it and focusing it 

on encouraging very low-NOX engines 

as early as possible provides a 

potentially useful and environmentally 

desirable alternative path. Thus these 

two concepts have been developed to 

provide complementary compliance 

paths obtaining equivalent overall NOX 

reductions, one focused on phasing in 

high-efficiency NOX aftertreatment and 

the other on achieving NOX control for 

all subject engines during the phase-in 

years at an average level between the 

Tier 3 and final Tier 4 standards levels. 

3. Standards for Smaller Engines 

a. Engines Under 25 hp 

We are finalizing the Tier 4 program 

we proposed for engines under 25 hp. 

In the proposal we presented our view 

that standards based on the use of PM 

filters should not be set at this time for 

the very small diesel engines below 25 

hp. We also discussed our plan to 

reassess the appropriate long-term 

standards in a technology review. 

However, for the nearer-term, we 

concluded that other proven PMreducing technologies such as diesel 

oxidation catalysts and engine 

optimization could be applied to 

engines under 25 hp. Accordingly, we 

proposed Tier 4 PM standards to take 

effect beginning in 2008 for these 

engines based on use of these 

technologies. 

In contrast to our proposals for other 

engine categories, the proposed Tier 4 

standards for this category elicited very 

little comment from the engine 

manufacturers other than an expression 

of support for deferring consideration of 

any more stringent standards pending 

results of a future technology review. 

The States and environmental 

organizations expressed disappointment 

that EPA had not proposed more 

stringent standards for these engines, 

given the very large number of these 

engines in the field and the significant 

risk they pose due to individuals’ 

exposure to diesel PM and air toxics. 

They urged more stringent 2008 PM 

standards and the adoption of standards 

obtaining emission reductions of 90% or 

more by the end of 2012. Emissions 

control manufacturers argued that more 

stringent 2008 standards based on the 

use of more efficient oxidation catalysts 

are feasible. 

As discussed in section II.B.4, we 

continue to believe that the standards 

we proposed for engines under 25 hp 

are feasible, and commenters in the 

nonroad diesel industry provided no 

comments to the contrary. Our reasons 

for not proposing more stringent Tier 4 

standards for these engines based on the 

use of PM filters and NOX aftertreatment 

were mainly focused on the cost of 

equipping these relatively low cost 

engines with such devices, especially 

considering the prerequisite need for 

electronic fuel control systems to 

facilitate regeneration. The comments 

supporting more stringent standards 

were not convincing, as they did not 

address these cost issues. However, we 

do agree that these small engines likely 

have a large impact on human health, 

and, as discussed in section VIII.A, we 

are reaffirming the plan we described in 

the proposal to reassess the appropriate 

long-term standards for these engines in 

a technology review to take place in 

2007. We will set more stringent 

standards for these engines at that time, 

if appropriate. 

We also disagree with comments 

supporting more stringent 2008 

standards that would require the use of 

diesel oxidation catalysts on all small 

engines. Although we agree that these 

catalysts can be applied so as to achieve 

emission reductions on some small 

engines, the emissions performance data 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38977 

we have analyzed do not support our 

setting a more stringent standard. 

Section 4.1.5 of the RIA summarizes 

such data showing a very wide range of 

engine-out PM emissions in this power 

category. Applying oxidation catalyst 

technology to these engines, though 

capable of some PM reduction if 

properly designed and matched to the 

application, is limited by sulfur in the 

diesel fuel. Specifically, precious-metal 

oxidation catalysts (which have the 

greatest potential for reducing PM) can 

oxidize the sulfur in the fuel and form 

particulate sulfates. Even with the 500 

ppm maximum sulfur fuel available 

after 2007, the sulfate production 

potential is large enough to limit what 

can be done to set more stringent 2008 

PM standards through the use of these 

catalysts. The 15 ppm maximum sulfur 

fuel available after 2010 will greatly 

improve the potential for use of 

oxidation catalysts, but as we discussed 

above, we believe that the much larger 

potential reduction afforded by PM filter 

technology warrants our waiting until 

the technology review in 2007 to 

evaluate the appropriate long-term 

standards for these engines. See section 

II.B.5 and RIA section 4.1.5 for further 

discussion. 

When implemented, the Tier 4 PM 

standard and related provisions we are 

adopting today for engines under 25 hp 

will yield an in-use PM reduction of 

over 50% for these engines, and large 

reductions in toxic hydrocarbons as 

well. Achieving these emission 

reductions is very important, 

considering the fact that many of these 

smaller engines operate in populated 

areas and in equipment without closed 

cabs—in mowers, portable electric 

power generators, small skid steer 

loaders, and the like. 

We are also adopting the alternative 

compliance option that we proposed for 

air-cooled, direct injection engines 

under 11 hp that are startable by hand, 

such as with a crank or recoil starter. As 

we explained in the proposal, the 

alternative is justified due (among other 

things) to these engines’ need for loose 

design fit tolerances, their small 

cylinder displacement and bore sizes, 

and the difficulty in obtaining 

components for them with tight enough 

tolerances (68 FR 28363, May 23, 2003). 

This alternative allows manufacturers of 

these engines to delay Tier 4 

compliance until 2010, and in that year 

to certify them to a PM standard of 0.45 

g/bhp-hr, rather than to the 0.30 g/bhphr PM standard applicable beginning in 

2008 to the other engines in this power 

category. As proposed, engines certified 

under this alternative compliance 

requirement will not be allowed to 

generate credits as part of the ABT 

program, although credit use by these 

engines will still be allowed. 

We received no adverse comments on 

this proposed alternative for qualifying 

engines under 11 hp. Euromot 

commented that there are hand-startable 

engines in the 11–25 hp range, and that 

we should extend the alternative 

compliance option to these engines as 

well. However, hand-startability is not 

the sole defining feature of engines for 

which we established this alternative. 

Rather, the alternative is for a class of 

engines typified by a combination of 

characteristics (very small, air-cooled, 

direct injection, hand-startable), which 

give rise to the potential technical 

difficulties noted above. To extend the 

alternative to other engines simply 

because they have a hand-start is not 

justified, because they do not share 

these technical difficulties (or do not 

share them to the same degree). Such an 

extension could also potentially 

encourage manufacturers of the many 

models of these larger engines to market 

a hand-start option simply to avoid 

more stringent standards. 

b. Standards for 25–75 hp Engines 

We proposed a 0.22 g/bhp-hr PM 

standard for 25–75 hp engines, to take 

effect in 2008. We also proposed a filterbased 0.02 g/bhp-hr PM standard for 

these engines, to take effect in 2013, the 

year in which filter-based technology for 

these engines is expected to be 

applicable on a widespread basis (see 

section II.A.1). Also in 2013, the 25–50 

hp engines would be subject to the 3.5 

g/bhp-hr NMHC+NOX standard already 

adopted for 50–75 hp engines (taking 

effect in 2008 as part of Tier 3). We are 

adopting all of these proposed standards 

in this final rule. 

The 2008 PM standard for these 

engines should maximize reduction of 

PM emissions using technology 

available in that year. We believe that 

the 2008 PM standard is feasible for 

these engines, based on the same engine 

or oxidation catalyst technologies 

feasible for engines under 25 hp in 

2008, following the introduction of 

nonroad diesel fuel with sulfur levels 

reduced below 500 ppm. We expect inuse PM reductions for these engines of 

over 50% (and large reductions in toxic 

hydrocarbons as well) over the five 

model years this standard would be in 

effect (2008–2012). These engines will 

constitute a large portion of the in-use 

population of nonroad diesel engines for 

many years after 2008. Although we are 

finalizing the 2013 standards for 25–75 

hp engines today, we are also 

reaffirming our commitment to 

conducting a technology review for 

these standards in 2007. This planned 

review is discussed in section VIII.A. 

Additional discussion of our feasibility 

assessment for the 2008 and 2013 

standards can be found in section II.B.4 

and RIA section 4.1.4. 

In comments, emissions controls 

manufacturers argued that more 

stringent 2008 standards for PM and 

NMHC based on the use of more 

efficient oxidation catalysts are feasible 

and should be adopted. Environmental 

organizations argued that PM and NOX 

standards for 2008 should be set at more 

stringent levels, based on the use of 

oxidation catalysts and improved engine 

optimization. The California Air 

Resources Board argued for more 

stringent 2008 standards for HC+NOX, 

PM and toxics, based on the use of 

oxidation catalysts. 

We disagree with the comments 

calling for more stringent 2008 

standards than proposed for 25–75 hp 

engines, based on the use of diesel 

oxidation catalysts. The standards we 

proposed and are adopting for these 

engines pull ahead sizeable PM 

reductions starting three years ahead of 

the earliest PM filter-based standards for 

any engine size. The pull-ahead 

standard level balances early reductions 

with the need to ensure that the PM 

filter-based standards and Tier 3 

NMHC+NOX standards are not 

jeopardized by an overemphasis on 

early reductions. Although we agree that 

oxidation catalysts can be applied to 

these engines, the emissions 

performance data we have analyzed do 

not support our setting a more stringent 

standard, for the same reasons described 

above in section II.A.3.a for engines 

under 25 hp. Refer to section II.B.4 and 

to section 4.1.4 of the RIA for additional 

discussion. For a discussion of 

comments opposed to new standards in 

2008, see sections II.A.1 and II.B of this 

preamble. 

We also do not agree that more 

stringent NOX requirements based on 

improved engine optimization are 

appropriate for these engines in 2008. In 

2001 we reviewed and confirmed the 

previously set NMHC+NOX emission 

standards that will be in effect for these 

engines during the time frame in 

question.31 Because of the focus we are 

putting on achieving large PM 

reductions from these engines as early 

as possible, we felt that it was important 

to strike a balance between PM and NOX 

control. As a result, we did not propose 

more stringent NOX standards for 50–75 

hp engines, and we proposed to apply 

31 ‘‘Nonroad Diesel Emissions Standards Staff 

Technical Paper,’’ EPA420–R–01–052, October 

2001. 
38978 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

the 3.5 g/bhp-hr NMHC+NOX standard 

to 25–50 hp engines in 2013 because 

this is the year in which the PM filterbased standard is being implemented. 

Requiring new NOX controls for these 

engines earlier than 2013 would add a 

third redesign step to those already 

called for in 2008 and 2013. This would 

add a potentially unacceptable amount 

of redesign workload, to a point that it 

could jeopardize our objective of 

bringing stringent PM control to these 

engines as early as possible. 

Consistent with the proposal, we are 

not setting more stringent NOX 

standards for engines below 75 hp at 

this time based on the use of NOX 

aftertreatment. As discussed in section 

4.1.2.3 of the RIA, a high degree of 

complexity and engine/aftertreatment 

integration will be involved in applying 

NOX adsorber technology to nonroad 

diesel engines. The similarity of larger 

nonroad engines (above 75 hp) to 

highway diesel engines, which will 

provide the initial experience base for 

this integration process, is key to our 

assessment that NOX adsorbers are 

feasible for these engines. On the other 

hand, although engines under 75 hp are 

gradually increasing in sophistication 

over time, the accumulation of 

experience with designing and 

operating these engines with more 

advanced technology clearly lags 

significantly behind the sizeable 

experience base already developed for 

larger engines. At this point, we are 

unable to forecast how quickly adequate 

experience may accrue. Because this 

experience is crucial to ensuring the 

successful integration of the engines 

with NOX adsorber technology, we are 

not adopting NOX adsorber-based 

standards for engines under 75 hp in 

this final rule. Rather, as discussed in 

section VIII.A, we plan to undertake a 

technology assessment in the 2007 time 

frame which would evaluate the status 

of engine and emission control 

technologies, including NOX controls, 

for engines less than 75 hp. 

As described in section II.A.1.a, we 

are providing two PM standard 

compliance options to engine 

manufacturers for 50–75 hp engines. As 

part of this, we also proposed a measure 

to ensure that it would not be abused by 

equipment manufacturers who use 

engines that do not meet the PM pullahead standard in 2008–2011, but who 

then switch engine suppliers to avoid 

PM filter-equipped engines in 2012 as 

well (68 FR 28360, May 23, 2003). We 

proposed that an equipment 

manufacturer making a product with 

engines not meeting the pull-ahead 

standard in any of the years 2008–2011 

must use engines in that product in 

2012 meeting the 0.02 g/bhp-hr PM 

standard; that is, the equipment 

manufacturer would have to use an 

engine from the same engine 

manufacturer or from another engine 

manufacturer choosing the same 

compliance option. We also solicited 

comment on possible alternative 

solutions using a numerical basis, 

describing an example that would 

require the percentage of 50–75 hp 

machines equipped with PM filters in 

2012 to be no less than the same 

percentage of 50–75 hp machines 

produced with non-pull-ahead engines 

in 2008–2011. 

The Engine Manufacturers 

Association (EMA) and Deere 

commented on the unenforceability of 

the proposed ‘‘no switch’’ measure as 

part of a broader objection to our 

proposal for 50–75 hp engines. They 

pointed out that changing equipment 

model designations could easily allow 

an equipment manufacturer seeking to 

avoid PM filter-equipped engines in 

2012 to declare a product in this model 

year a ‘‘new product,’’ not the same as 

the 2008–2011 product. We have 

concluded that there is indeed potential 

for this abuse to occur and, although no 

one commented specifically on the 

alternative approach, we believe it 

clearly addresses this problem because 

it does not depend on product 

designations. 

Therefore, we are adopting a 

provision to discourage engine 

switching based on this alternative 

approach. An equipment manufacturer 

who uses 50–75 hp engines will have 

three options: 

(1) The manufacturer may exclusively use 

engines certified to the 0.22 g/bhp-hr PM 

standard (including through use of ABT 

credits) over the 2008–2011 period. This 

manufacturer is then free to use any number 

of 50–75 hp engines not certified to the 0.02 

g/bhp-hr standards in 2012. 

(2) The manufacturer may exclusively use 

engines not certified to the 0.22 g/bhp-hr PM 

standard over the 2008–2011 period. This 

manufacturer must then use only 50–75 hp 

engines that are certified to the 0.02 g/bhphr standards in 2012 (including through use 

of ABT credits). 

(3) The manufacturer may use a mix of 

engines in 2008–2011. In this case, the 

manufacturer must calculate the percentage 

of 50–75 hp engines used (in U.S.-directed 

equipment) over the 2008–2010 period that 

are not certified to the 0.22 g/bhp-hr PM pullahead standard. Then the percentage of 50– 

75 hp engines this manufacturer uses in 2012 

that are certified to the 0.02 g/bhp-hr PM 

standard must be no less than this 2008–2010 

non-pull-ahead percentage figure minus a 5% 

margin.32 

32 The 2011 production is not included in the 

percentage calculation to avoid the need for postAs an example of this third option, 

consider an equipment manufacturer 

who does not use the transition 

flexibility provisions (described in 

section III.B), and over the 2008–2010 

period makes 1000 50–75 hp machines 

for use in the U.S., 200 (20%) of which 

use engines not certified to the 0.22 g/ 

bhp-hr standard. In 2012, that 

manufacturer must make at least 15% of 

his 50–75 hp machines for use in the 

U.S. using engines certified to the 0.02 

g/bhp-hr standard. We feel that the 5% 

margin is needed to allow for some 

reasonable sales shifts within the 

manufacturer’s product offering over 

time, but is small enough to ensure that 

any possible advantage gained from 

selling higher-emissions products 

remains minimal. Equipment 

manufacturers must keep production 

records sufficient to prove compliance. 

This restriction and the percentage 

calculation will not apply to any 2008– 

2012 engines at issue that are being 

produced under the equipment 

manufacturer transition flexibility 

provisions discussed in section III.B. 

For example, if in addition to the 200 

engines in 2008–2010 not certified to 

the 0.22 g/bhp-hr standard in the above 

example, this manufacturer also used 

500 previous-tier engines in 2008–2010 

under the flexibility allowance program, 

his percentage target for PM filterequipped engines in 2012 would be 

35% of all the engines used in 2012 that 

are not previous-tier engines under the 

flexibility allowance program. 33 

4. Standards for Engines Above 750 hp 

We are adopting different Tier 4 

standards for over 750 hp engines from 

those we proposed, and we are also 

adopting different implementation dates 

for these engine standards, though both 

the proposed and final programs have as 

their primary focus the implementation 

of high-efficiency exhaust emission 

controls as quickly as possible. The 

approach being adopted reflects our 

careful review of the technical issues 

presented by these engines. For some of 

these engines, we are accelerating 

standards based on the use of 

aftertreatment controls. For others, we 

are deferring a decision on such 

aftertreatment-based standards. This 

approach represents a feasible and 

efficient approach to redesigning 

2011 confirmation of production volumes which, as 

it would occur in 2012, would be too late to easily 

re-focus 2012 production if the confirmed volumes 

differ from projections. It is not likely that 

manufacturers would abuse the program by 

switching engine suppliers for this one year of 

production. 

33 That is: [200/(1000–500)] = 40%; subtracting 

the 5% margin then yields 35%. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38979 

engines and installing aftertreatment in 

a coordinated, orderly manner over a 

decade or more, and will achieve major 

reductions in PM and NOX from these 

large diesel engines. 

Under the proposal, all engines above 

750 hp were treated the same, with a 

phase-in of PM and NOX aftertreatment 

technology that started in 2011 and 

finished in 2014. The final standards are 

based on our evaluation of the differing 

technical issues presented by the two 

primary kinds of equipment in this 

category, mobile power generation 

equipment (generator sets) and mobile 

machinery. For both generator sets and 

mobile machinery, PM aftertreatmentbased standards will start in 2015, with 

no prior phase-in. EPA is replacing the 

proposed phase-in with a PM standard 

starting in 2011 that is comparable to 

the overall level of control that the 

proposed phase-in would achieve. 

Differences within these applications, 

however, call for different approaches to 

the implementation of NOX 

aftertreatment technology. For generator 

sets above 1200 hp, an aftertreatmentbased NOX standard will start in 2011, 

three years earlier than the date we 

proposed for full implementation of 

such standards. For generator sets below 

1200 hp, the same aftertreatment-based 

NOX standard will start in 2015. As with 

the PM standard, there is no phase-in. 

For engines used in mobile machinery, 

which is assumed to include all 

equipment that is not a generator set, 

EPA is deferring a decision on setting 

aftertreatment-based NOX standards to 

allow additional time to evaluate the 

technical issues involved in adapting 

NOX adsorber technology to these 

applications and engines. However, EPA 

is adopting a NOX standard for these 

engines starting in 2011 that will 

achieve large NOX reductions by relying 

on engine-based emissions control 

technology. Consistent with the 

different approaches we are taking to 

setting standards for engines above and 

below 750 hp, we are also adopting 

restrictions on ABT credit use between 

these power categories, as described in 

section III.A. 

Consistent with the approach we took 

in previous standard-setting for these 

engines, we proposed that nonroad 

diesels above 750 hp be given more lead 

time than engines in other power 

categories to fully implement Tier 4 

standards, due primarily to the 

relatively long product design cycles 

typical of these high-cost, low-sales 

volume engines and machines. 

Specifically, we proposed that this 

category of engines move directly from 

Tier 2 to Tier 4, and that the Tier 4 PM 

standard be phased in for these engines 

on the same 50–50–50–100% schedule 

as the NOX and NMHC phase-in 

schedule, over the 2011–2014 model 

years. This would provide engine 

manufacturers with up to 8 years of 

design stability to address concerns 

specific to this category. Although we 

expressed our belief that these proposed 

provisions would enable the 

manufacturers to meet proposed Tier 4 

engine standards, we also acknowledged 

concerns the manufacturers had 

expressed to us, and asked for comment 

on whether this category, or some subset 

of it defined by hp or application, 

should have a later phase-in start date, 

a later phase-in end date, adjusted 

standards, additional equipment 

manufacturer transition flexibility 

provisions, or some combination of 

these (68 FR 28364, May 23, 2003). 

Comments from manufacturers of 

engines and equipment in this power 

category expressed their widespread 

view that the proposed standards were 

inappropriate in critical respects. In 

addition to reiterating the need for extra 

lead time due to long product design 

cycles, they pointed to difficulties with 

aftertreatment placement, with 

fabrication of the large filters that would 

be needed for these engines, with 

potential failures caused by uneven soot 

loading and regeneration in large filters, 

with stresses due to thermal gradients 

across large filters, and with mechanical 

stresses in mining applications with 

high shock loads. The manufacturers 

noted that aftertreatment-based 

standards for NOX and PM were feasible 

for engines used in large mobile power 

generators. However, manufacturers did 

not believe aftertreatment-based NOX 

standards could be implemented in the 

time frame proposed for engines used in 

large mobile machinery such as 

bulldozers and mine haul trucks. States, 

environmental organizations, and 

manufacturers of emissions controls, on 

the other hand, expressed support for 

the standards we proposed for these 

engines. 

After evaluating these issues, EPA is 

adopting an approach that tailors the 

standards to the circumstances 

presented by the different kinds of 

engines in this power category. The 

NOX standards we are adopting will 

achieve effective NOX control by 

accelerating the proposed schedule for 

final NOX standards based on highefficiency NOX aftertreatment for the 

largest generator sets, and by requiring 

engines in other generator sets to also 

meet aftertreatment-based NOX 

standards, although we are delaying the 

implementation date for these standards 

compared to the implementation 

schedule we proposed. We believe that 

NOX adsorber technology will be 

feasible for these generator set engines. 

We also believe that they may be an 

especially attractive application for 

Selective Catalytic Reduction (SCR) 

technology, which relies on the 

injection of urea into the exhaust 

stream. There are many stationary diesel 

generator sets using SCR today. Large 

mobile generator sets, though moved 

from location to location, operate much 

like stationary units once in place, with 

fuel (and potentially urea) delivered and 

replenished periodically. See section 

II.B.3 for further discussion. 

For equipment other than generator 

sets, we are deferring a decision on 

setting aftertreatment-based NOX 

standards to allow additional time to 

evaluate the technical issues involved in 

adapting NOX control technology to 

these applications and engines. We are 

still evaluating the issues involved for 

these engines to achieve a more 

stringent NOX standard, and believe that 

these issues are resolvable. We intend to 

continue evaluating the appropriate 

long-term NOX standard for mobile 

machinery over 750 hp and expect to 

announce further plans regarding these 

issues (we are currently considering 

such an action in the 2007 time frame). 

The basis for the 0.50 g/bhp-hr NOX 

standard we are adopting for generator 

sets over 750 hp is discussed in section 

II.B.3. We are also modifying the PM 

and NMHC standards we proposed (as 

well as certain implementation dates for 

these provisions), and modifying our 

proposed approach to ensuring transient 

emissions control for these engines 

(discussed in section III.F). The Tier 4 

standards for engines over 750 hp are 

shown in table II.A–4. 
38980 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

TABLEII.A–4.—TIER4 STANDARDSFORENGINESOVER750 HP(G/BHP-HR) 

2011 

PM X NMHC PM NOX NMHC 

Engines used in: 

generator sets ≤1200 hp........................................0.0752.60.300.020.500.14 

generator sets >1200 hp........................................0.0750.500.300.02No new standard 0.14 

all other equipment.................................................0.075 2.60.300.03No new standard 0.14 

2015 

NO

Unlike NOX control technology, we 

believe that the more advanced state of 

PM filter technology development today 

makes their availability for these 

engines by 2015, with over ten years of 

development lead time, more certain, 

and so we are setting PM standards for 

both mobile machinery and generator 

sets based on use of this technology. We 

note in section II.B.3 that achieving 

durable PM filter designs for these large 

applications will likely require the use 

of wire mesh filter technology rather 

than the somewhat more efficient wall 

flow ceramic-based technology 

applicable to smaller engines, justifying 

the somewhat higher level for the 2015 

PM standards shown in table II.A–4 

(0.03 or 0.02 g/bhp-hr compared to 0.01 

g/bhp-hr). Section II.B.3 also contains 

discussion of our bases for the other 

Tier 4 standard levels in this category. 

We believe that the 2015 

implementation year (versus the 

proposed 2014 date for the fully phasedin standard) is necessary to allow 

development of the requisite 

technologies for these large engines, and 

to deal with the redesign workload Tier 

4 will create for the many engine and 

equipment models in this category 

which, as noted, typically have very low 

production volumes and long product 

cycles. 

For the purpose of determining which 

nonroad engines are subject to the 

generator set standards, we are defining 

a generator set engine as: ‘‘An engine 

used primarily to operate an electrical 

generator or alternator to produce 

electric power for other applications.’’ 

This definition makes it clear that 

generator set engines do not include 

engines used in machines such as mine 

trucks that do mechanical work but that 

employ engine-powered electric motors 

to propel the machine, but they do 

include engines in nonroad equipment 

for which the primary purpose is to 

generate electric power, even if the 

machine is also self-propelled. 

Similar to other power categories, we 

proposed a 50% phase-in to the final 

Tier 4 PM, NOX and NMHC standards, 

with opportunity to average PM and 

NOX between phase-in and phase-out 

engines in the 2011–2013 phase-in years 

via the ABT program. Because in this 

rule we are no longer phasing in to a 

final NOX standard for some engines 

over 750 hp, it no longer makes sense 

to express the 2011 standards for these 

engines in this manner. Instead we are 

setting brake-specific emission 

standards effective in 2011. 

Furthermore, to avoid further 

complicating an already complex 

standards structure, we are adopting 

this pattern for the entire category, even 

with engines such as those used in 

generator sets for which the standards 

could still be expressed as a percent 

phase-in to final standards. Except for 

the pull-ahead of the long-term NOX 

standard for large generator sets (which 

will increase the environmental benefit 

compared to the proposal), these 2011 

PM and NOX standards essentially 

correspond to averaged standards under 

a 50% phase-in to aftertreatment-based 

standards, hence our conclusion that the 

Tier 4 program will provide a level of 

control in 2011 that is substantially 

equivalent to that of the proposal. In 

addition, PM and NOX emissions 

averaging through the ABT program will 

allow a manufacturer to comply by 

phasing in aftertreatment technologies 

as in the proposed program, should they 

desire to do so. Although there is no 

such averaging program for NMHC, the 

2011 NMHC standard can be achieved 

without the use of advanced 

aftertreatment (as explained in section 

II.B.3), thus helping to enable a 

manufacturer to pursue this compliance 

strategy if desired. 

This approach involving separate 

2011 and 2015 standards is comparable 

to the proposed percent phase-in 

approach with emissions averaging. We 

believe that it enables manufacturers to 

redesign engines and equipment in a 

coordinated, orderly manner over a 

decade or more, and effectively gives 

targeted additional flexibility to the 

industry. Given the continuing 

availability of emissions averaging, we 

do not view this change as the creation 

of an additional, separate tier of 

standards compared to the proposal’s 

phase-in of the Tier 4 standards. 

5. Establishment of New Power 

Categories 

We are finalizing our proposal to 

regroup the nine power categories 

established for previous tiers into the 

five Tier 4 power categories shown in 

table II.A–1. As we explained in the 

proposal, this regrouping will more 

closely match the degree of challenge 

involved in transferring advanced 

emissions control technology from 

highway engines to nonroad engines. 

The proposed choice of 75 hp as the 

appropriate cutpoint for applying 

aftertreatment-based NOX control drew 

particular attention. In the proposal, we 

recognized that there is not an abrupt 

power cutpoint above and below which 

the highway-derived nonroad engine 

families do and do not exist, but noted 

further that 75 hp is a more appropriate 

cutpoint to generally identify nonroad 

engines in Tier 4 that will most likely 

be using highway-like engine 

technology than either of the closest 

previously-adopted power category 

cutpoints of 50 or 100 hp. Nonroad 

diesels produced today with rated 

power above 75 hp (up to several 

hundred hp) are mostly variants of 

nonroad engine platforms with four or 

more cylinders and per-cylinder 

displacements of one liter or more. 

These in turn are largely derived from 

or are similar to heavy-duty highway 

engine platforms. Even where nonroad 

engine models above 75 hp are not so 

directly derived from highway models, 

they typically share many common 

characteristics such as displacements of 

one liter per cylinder or more, direct 

injection fueling, turbocharging, and, 

increasingly, electronic fuel injection. 

These common features provide key 

building blocks in transferring highefficiency exhaust emission control 

technology from highway to similar 

nonroad diesel engines. We therefore 

proposed to regroup power ratings using 

the 75 hp cutpoint. 

The Engine Manufacturers 

Association and Euromot, which 

together represent the companies that 

make all but a tiny fraction of nonroad 

diesel engines sold in the U.S., 

expressed their support for the 75 hp 

cutpoint, as did every individual engine 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38981 

manufacturer who commented on this 

subject. These companies generally 

endorsed EPA’s reasoning that the 75 hp 

level is appropriate to ‘‘delineate those 

engines (and applications) for which the 

application of on-highway like NOX 

aftertreatment technologies is not likely 

to be feasible or practical’’ (EMA 

Comments p.10). 

However, the Association of 

Equipment Manufacturers (AEM) and 

the equipment manufacturer IngersollRand commented that 100 hp is the 

more appropriate cutpoint for 

application of advanced NOX control 

technology. They based this view on 

their observations that 75–100 hp 

engines do not share many of the 

characteristics of highway diesels, thus 

making technology transfer from the 

highway sector very costly, and 

customers will be negatively affected 

due to the relatively large cost impacts 

of NOX aftertreatment on these smaller 

engines. They also argued that the 75 hp 

cutpoint would create significant 

misalignment in the global marketplace 

because European regulations do not 

use this cutpoint. 

We agree with the equipment 

manufacturers’ observation that there 

are engines above 75 hp without 

turbocharging or electronic controls. 

However, EPA did not choose the 75 hp 

cutpoint with the expectation that all 

engines above it had the same 

technology characteristics. There is a 

continuum in the degree to which key 

technology characteristics exist on 

engines throughout the power spectrum, 

and the 75 hp cutpoint was based on 

information from the current fleet of 

engines and on manufacturers’ and 

EPA’s expectations for future design 

trends, showing there is a marked 

difference in the prevalence of these and 

other key engine design characteristics 

for engines above and below 75 hp, and 

that, over time, 75–100 hp engines 

increasingly share advanced technology 

characteristics common in larger 

engines. Clear evidence of this trend 

over recent model years is documented 

in the RIA, section 4.1.4. As discussed 

in section II.B.2, the kind of engine 

technology generally employed by 

engines in the 75–100 hp range, 

combined with the lead time and phasein provided for the Tier 4 NOX 

standards, leads us to conclude that 

highway-like NOX aftertreatment can be 

transferred to these engines. In addition, 

since our proposal, the Council of the 

European Union (EU) has issued a 

revised final version of new nonroad 

diesel emission standards that 

essentially aligns their power cutpoints 

with our own, including adoption of the 

75 hp cutpoint for advanced technology 

NOX control. EPA does not believe that 

the costs of meeting the NOX standard 

for engines in the 75–100 hp range are 

unreasonable, and we refer the reader to 

section VI for a detailed discussion of 

our cost analysis for engines and 

equipment meeting Tier 4 standards in 

this power range. Moreover, EPA firmly 

believes such standards are 

technologically feasible for 75–100 hp 

engines. (See section II.B.2.) 

Ingersoll-Rand also expressed concern 

that the proposed consolidation of 3 

previous power categories into a single 

175–750 hp category creates significant 

hardship by requiring the introduction 

of aftertreatment technologies in a single 

year, contrasting this with the Tier 2 

standards, which phased in over 2001– 

2003 for these engines. In response, we 

note that the Tier 3 standards, which 

were set in the same rule that 

established the Tier 2 standards, will be 

introduced in a single year for these 

engines (2006), and that the Tier 2 

phase-in over 3 years was established in 

response to particular issues and 

opportunities that were identified, 

specific to that time frame (see 62 FR 

50181, September 24, 1997). In addition 

to the gradual phase-in of Tier 4 

standards over several years, we are 

adopting significant flexibility 

provisions specifically to provide 

adequate lead time for equipment 

manufacturers to make the transition to 

the new standards, including some 

provisions that provide additional 

flexibility from what we proposed, as 

explained in section III.B. 

6. CO Standards 

We proposed minor changes in CO 

standards for some engines solely for 

the purpose of helping to consolidate 

power categories. We stated in the 

proposal that we were not exercising 

our authority to revise the CO standard 

for the purpose of improving air quality, 

but rather for purposes of administrative 

efficiency. However, manufacturers 

objected to these proposed changes, 

citing technological feasibility concerns, 

and a lack of parity with highway diesel 

and nonroad spark-ignition engines, 

given that existing CO standards levels 

for nonroad engines are already five 

times lower than the standard level for 

highway engines. 

Because we proposed the CO standard 

changes for the sake of simplifying and 

consolidating power categories and not 

because of any technical considerations 

relating to emission reductions, we do 

not believe it productive to take issue 

with the views expressed that these 

proposed changes raise serious 

feasibility concerns. We instead are 

withdrawing this aspect of the proposal, 

the result being that the existing CO 

standards remain in place. In doing so, 

we are not considering or reexamining 

(and at proposal did not consider or 

reexamine) the substantive basis for 

those standards. Having multiple CO 

standards within a power category will, 

at worst, create minor inconveniences in 

certification and compliance efforts. As 

a result, in the less than 25 hp category, 

Tier 4 engines below 11 hp will 

continue to be subject to a different CO 

standard than 11–25 hp engines, 

identical to Tier 2. Likewise, different 

CO standards will continue to apply in 

Tier 4 to engines above and below 50 hp 

in the 25–75 hp category. 

We do note, however, that we are 

applying new certification tests to all 

pollutants covered by the rule, the result 

being that Tier 4 engines will have to 

certify to CO standards measured by the 

transient test (NRTC) (which includes a 

cold start test), and the NTE. Our intent 

in adopting these new certification 

requirements is not to alter the level of 

stringency of the standard but rather to 

ensure robust control of emissions to 

this standard in use. The CO standards 

remain readily achievable using these 

tests, and we anticipate that no 

additional engine adjustments are 

necessary for the standards to be 

achievable (so there are no significant 

associated costs). We also explain there 

that the CO standards can be achieved 

without jeopardizing the ability to 

achieve all of the other engine 

standards. 

7. Crankcase Emissions Control 

We currently require the control of 

crankcase emissions from naturallyaspiriated nonroad diesel engines. We 

proposed to extend this requirement to 

turbocharged nonroad diesel engines as 

well, starting in the same model year 

that Tier 4 exhaust emission standards 

first apply in each power category. 

EMA opposed the proposed 

extension, reiterating concerns 

expressed in comments on a similar 

proposed provision in the 2007 heavyduty highway rule, including concerns 

over the impact that recirculating 

crankcase emissions may have on the 

feasibility of engine standards over the 

full useful life. These concerns are 

addressed in the Summary and Analysis 

of Comments document for that rule, 

which is included in the docket for 

today’s rule. Besides the feasibility 

issues raised by EMA for nonroad 

diesels that are addressed in the 

highway rule, two nonroad-specific 

issues were raised as well: (1) The need 

to design crankcase emission control 

systems that operate at the high 

angularity experienced by some 
38982 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

nonroad machines on uneven ground, 

and (2) the concern that this 

requirement adds to the large number of 

‘‘first time’’ requirements being adopted 

for Tier 4. We agree that high angularity 

operation may add new design 

considerations for these controls, but do 

not see how it would pose a serious 

barrier that could not be overcome in 

time. The grouping of new EPA 

requirements in a specific model year is 

an important objective of our program 

aimed at providing stability to the 

design process, a goal much supported 

by the engine manufacturers. We have 

accounted for this in assessing 

feasibility, costs, and flexibility needs 

for the program. One flexibility we are 

providing is the three-path opportunity 

to satisfy our crankcase control 

requirement, as described below. In fact, 

in its written comments EMA 

recommended that, if EPA were to 

proceed with crankcase emission 

control requirements for Tier 4, it adopt 

all three options for demonstrating 

compliance. This is indeed what we are 

doing. 

Thus, as proposed, in addition to 

allowing for compliance through the 

routing of crankcase emissions to the 

engine air intake system, we are also 

allowing manufacturers to instead meet 

the requirement by routing the 

crankcase gases into the exhaust stream, 

provided they keep the combined total 

of the crankcase emissions and the 

exhaust emissions below the applicable 

exhaust emission standards. Also as 

proposed, we are allowing 

manufacturers to instead meet the 

requirement by measuring crankcase 

emissions instead of completely 

eliminating them, provided 

manufacturers add these measured 

emissions to exhaust emissions in 

assessing compliance with exhaust 

emissions standards. Manufacturers 

using this option must also modify their 

exhaust deterioration factors or develop 

separate deterioration factors to account 

for increases in crankcase emissions as 

the engine ages, and must ensure that 

crankcase emissions can be readily 

measured in use. We see no reason to 

treat naturally-aspirated engines 

differently than turbocharged engines, 

and so are allowing these options for all 

Tier 4 engines subject to the crankcase 

control requirement, both turbocharged 

and naturally-aspirated. The wording of 

the proposed regulations limiting the 

options to turbocharged engines was 

inadvertent. 

8. Prospects for International 

Harmonization 

We received numerous comments, 

especially from engine and equipment 

manufacturers, stressing the need for 

EPA to work with other governmental 

standards-setting bodies to harmonize 

standards. We recognize the importance 

of harmonization of international 

standards and have worked diligently 

with our colleagues in Europe and Japan 

to achieve that objective. Harmonization 

of these standards will allow 

manufacturers continued access to 

world markets and lower the required 

research and development and tooling 

costs needed to meet different 

standards. We will continue to work 

with standards-setting governmental 

entities and with foreign and domestic 

manufacturers. 

In October 2003, the Council and 

Parliament of the European Union 

reached agreement on revisions to a 

proposal developed by the European 

Commission that would amend 

Directive 97/68/EC to include nonroad 

diesel emissions standards similar to 

those in our Tier 4 program, and, as in 

the U.S., coordinated with low sulfur 

diesel fuel requirements in Europe. This 

revised proposal has since been 

finalized.34 This revised Directive aligns 

well with our program in the Tier 4 time 

frame, even more so than did the 

original Commission proposal. It also 

closely aligns with our Tier 3 standards 

in the Tier 3 time frame. 

For engines of 50–750 hp, the 

Directive’s standards are very closely 

aligned with our own Tier 4 standards, 

including emissions levels, 

implementation dates, the defined 

power categories, and the lower hp limit 

of NOX control based on high-efficiency 

exhaust emission controls (75 hp). 

Exceptions are noted below: 

• The 2008 PM standard level for 50– 

75 hp engines (the equivalent of 0.3 g/ 

bhp-hr vs our 0.22 g/bhp-hr level). Note, 

however, that we do allow certification 

to the 0.3 g/bhp-hr level as an option, 

provided the manufacturer must then 

meet our 0.02 g/bhp-hr standard in 

2012, one year earlier than otherwise. 

• The 2013 PM standard level for 50– 

75 hp engines (the equivalent of 0.01 g/ 

bhp-hr vs our 0.02 g/bhp-hr level). 

• An October 1, 2014 start for the 

final 75–175 hp NOX standard (the same 

as our proposed date), compared to the 

December 31, 2014 date we are adopting 

in this final rule. 

• For constant speed engines: no Tier 

4-equivalent standards. Also, the EU’s 

Tier 3-equivalent standards are not 

implemented on these engines until 

2011–2012. 

34 Council of the European Union, ‘‘Directive of 

the European Parliament and of the Council 

amending Directive 97/68/EC’’, March 15, 2004. 

As the EU program does not provide 

for emissions averaging, the alternative 

NOX standards we are setting for 75–750 

hp engines are the NOX levels at which 

the EU standards are generally aligned 

during our NOX phase-in years. The EU 

Directive also includes transition 

flexibility provisions for equipment 

manufacturers similar to those in our 

program, discussed in section III.B. 

The EU program for nonroad diesels 

has not adopted or proposed any current 

or future standards for engines above 

750 hp or below 25 hp, and its revised 

Directive for 25–50 hp engines does not 

subject them to any future standards 

beyond those entering into force in 2007 

(equivalent to 0.45 g/bhp-hr PM and 5.6 

g/bhp-hr hydrocarbon+NOX), in contrast 

to our 2013 standards based the use of 

PM filters and more advanced enginebased control technologies (0.02 g/bhphr PM and 3.5 g/bhp-hr NMHC+NOX). 

However, as discussed further in section 

VIII.A, the EU Directive includes plans 

to conduct a future technology review of 

appropriate standards for engines below 

50 hp and above 750 hp. The year that 

this is planned for is 2007, the same 

year in which we are planning a 

technology review for engines below 75 

hp. Considering progress to date, and 

announced plans for reviews in 2007, 

we believe that prospects for 

harmonized standards are excellent. 

9. Exclusion of Marine Engines 

For reasons outlined in the proposal, 

we are not applying Tier 4 standards to 

the marine diesel engines under 50 hp 

that are covered under our Tier 1 and 

2 standards. We believe it is more 

appropriate to consider more stringent 

standards for a range of marine diesel 

engines, including these, in a future 

action. It should be noted that the 

existing Tier 2 standards will continue 

to apply to marine diesel engines under 

50 hp until that future action is 

completed. We did not receive any 

adverse comments on this proposed 

approach. 

B. Are the New Standards Feasible? 

Today we are finalizing a program of 

stringent new standards for a broad 

category of nonroad diesel engines 

coupled with a new nonroad diesel fuel 

standard that dramatically lowers the 

sulfur level in nonroad diesel fuel 

ultimately to 15 ppm. We believe these 

standards are technically feasible in the 

leadtime provided given the availability 

of 15 ppm sulfur fuel and the rapid 

progress to develop the needed emission 

control technologies. We acknowledge, 

as pointed out by a number of 

commenters, that these standards will 

be challenging for industry to meet, in 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38983 

part due to differences in operating 

conditions and duty cycles for nonroad 

equipment and the diesel engines used 

in that equipment. Also, we recognize 

that transferring and effectively 

applying these technologies, which have 

largely been developed for highway 

engines, will require additional time 

after the application of the technology to 

on-highway engines. Diesel engine 

industry commenters and 

environmental stakeholder commenters 

on our proposal consistently agreed 

with our position that for most engine 

horsepower categories the technologies 

to meet the standards exist and that the 

transfer of these technologies to nonroad 

is possible. The biggest difference of 

opinions in the range of comments 

received by the Agency concerns the 

timing of the emission standards and 

the flexibility provisions (i.e., the 

leadtime necessary to transfer the 

technology). One of the most important 

tasks for a feasibility analysis is to 

determine the appropriate amount of 

development time needed to 

successfully bring new technologies to 

market. We have carefully weighed the 

desire to have clean engines sooner, 

with the challenges yet to be overcome 

in applying the technologies to nonroad 

engines and equipment, in determining 

the appropriate timing and emission 

levels for the standards finalized today. 

The RIA associated with today’s 

action contains a detailed description 

and analysis of diesel emission control 

technologies, issues specific to applying 

these technologies to nonroad engines, 

and why we believe the new emission 

standards are feasible. Additional indepth discussion of these technologies 

can be found in the final RIA for the 

HD2007 emission standards, the final 

RIA for the HD2004 emission standards, 

the 2002 Highway Diesel Progress 

Review and the recently released 

Highway Diesel Progress Review Report 

2.35 36 37 38 The following sections 

summarize the challenges to applying 

35 Regulatory Impact Analysis: Heavy-Duty 

Engine and Vehicle Standards and Highway Diesel 

Fuel Sulfur Control Requirements, United States 

Environmental Protection Agency, December 2000, 

EPA420–R–00–026. Copy Available in EPA Air 

Docket A–2001–28 Item II–A–01. 

36 Regulatory Impact Analysis: Control of 

Emissions of Air Pollution from Highway HeavyDuty Engines, United States Environmental 

Protection Agency, June 2000, EPA420–R–00–010. 

Copy available in EPA Air Docket A–2001–28 Item 

II–A–02. 

37 Highway Diesel Progress Review, United States 

Environmental Protection Agency, June 2002, EPA 

420–R–02–016. Copy available in EPA Air Docket 

A–2001–28 Item II–A–52. 

38 Highway Diesel Progress Review Report 2, 

United States Environmental Protection Agency, 

March 2004, EPA420–R–04–004. Copy available in 

Docket OAR–2003–0012–0918. 

these technologies to nonroad engines 

and why we believe the emission 

standards finalized today are technically 

feasible in the leadtime provided. 

1. Can Advanced Diesel Emission 

Control Technologies Be Applied to 

Nonroad Engines and Equipment? 

The emission standards and the 

introduction dates for those standards, 

as described earlier in this section, are 

premised on the transfer of diesel 

engine technologies being or already 

developed to meet light-duty and heavyduty vehicle standards that begin in 

2007. The advanced technology 

standards that we are finalizing today 

for engines over 25 horsepower will 

begin to go into effect four years later. 

This time lag between equivalent 

highway and nonroad diesel engine 

standards is necessary in order to allow 

time for engine and equipment 

manufacturers to further develop these 

highway technologies for nonroad 

engines and to align this program with 

nonroad Tier 3 emission standards that 

begin to go into effect in 2006. 

This section summarizes the 

engineering challenges to applying 

advanced emission control technologies 

to nonroad engines and equipment, and 

why we believe that technologies 

developed for highway diesel engines 

can be further refined to address these 

issues in a timely manner for nonroad 

engines consistent with the emission 

standards finalized today. 

a. Nonroad Operating Conditions and 

Exhaust Temperatures 

Nonroad equipment is highly diverse 

in design, application, and typical 

operating conditions. This variety of 

operating conditions affects emission 

control systems through the resulting 

variety in the torque and speed 

demands (i.e., power demands). In our 

proposal, we highlighted the challenge 

for design and implementation of 

advanced emission control technologies 

posed by this wide range in what 

constitutes typical nonroad operation. 

Some commenters emphasized their 

concerns regarding this issue as well, 

and their belief that these issues make 

the application of the technology to 

nonroad infeasible. While we recognize 

and agree with the commenters 

regarding the nature of the challenges, 

we disagree with their conclusion 

regarding feasibility because, as 

described in the following section, we 

see a clear path to overcome the 

challenges. 

The primary concern for catalystbased emission control technologies is 

exhaust temperature. In general, exhaust 

temperature increases with engine 

power and can vary dramatically as 

engine power demands vary. For 

catalyzed diesel particulate filters 

(CDPFs), exhaust temperature 

determines the rate of filter 

regeneration, and if too low, causes a 

need for supplemental means to ensure 

proper filter regeneration. In the case of 

the CDPF, it is the aggregate soot 

regeneration rate that is important, not 

the regeneration rate at any particular 

moment in time. A CDPF controls PM 

emissions under all conditions and can 

function properly (i.e., not plug) even 

when exhaust temperatures are low for 

an extended time and the regeneration 

rate is lower than the soot accumulation 

rate, provided that occasionally exhaust 

temperatures and thus the soot 

regeneration rate are increased enough 

to regenerate the CDPF. Similarly, there 

is a minimum temperature (e.g., 200 °C) 

for NOX adsorbers below which NOX 

regeneration is not readily possible and 

a maximum temperature (e.g., 500 °C) 

above which NOX adsorbers are unable 

to effectively store NOX. Therefore, 

there is a need to match diesel exhaust 

temperatures to conditions for effective 

catalyst operation under the various 

operating conditions of nonroad 

engines. 

Although the range of products for 

highway vehicles is not as diverse as for 

nonroad equipment, the need to match 

exhaust temperatures to catalyst 

characteristics is still present. This is an 

important concern for highway engine 

manufacturers and has been a focus of 

our ongoing 2007 diesel engine progress 

review. There we have learned that 

substantial progress is being made to 

broaden the operating temperature 

window of catalyst technologies while 

at the same time to design engine 

systems to better control average 

exhaust temperatures (for ongoing 

catalyst performance) and to attain 

periodically higher temperatures (to 

control PM filter regeneration and NOX 

adsorber desulfation). Highway diesel 

engine manufacturers are working to 

address this need through modifications 

to engine design, modifications to 

engine control strategies, and 

modifications to exhaust system 

designs. New engine control strategies 

designed to take advantage of engine 

and exhaust system modifications can 

be used to manage exhaust temperatures 

across a broad range of engine 

operation. The technology solutions 

being developed for highway engines to 

better manage exhaust temperature are 

built upon the same emission control 

technologies (i.e., advanced air handling 

systems and electronic fuel injection 

systems) that we expect nonroad engine 
38984 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

manufacturers to use in order to comply 

with the existing Tier 3 emission 

standards. 

Matching the emission control 

technology and the operating 

temperature window of the broad range 

of nonroad equipment may be 

somewhat more challenging for nonroad 

engines than for many highway diesel 

engines simply because of the diversity 

in equipment design and equipment 

use. Nonetheless, the problem has been 

successfully solved in highway 

applications facing low exhaust 

temperature performance situations as 

difficult to address as any encountered 

by nonroad applications. The most 

challenging temperature regime for 

highway engines are encountered at 

very light-loads as typified by congested 

urban driving with periods of extended 

idle operation. Under congested urban 

driving conditions, exhaust 

temperatures may be too low for 

effective NOX reduction with a NOX 

adsorber catalyst. Similarly, exhaust 

temperatures may be too low to ensure 

passive CDPF regeneration. To address 

these concerns, light-duty diesel engine 

manufacturers have developed active 

temperature management strategies that 

provide effective emissions control even 

under these difficult light-load 

conditions. Toyota has shown with their 

prototype diesel particulate NOX 

reduction (DPNR) vehicles that changes 

to EGR and fuel injection strategies can 

realize an increase in exhaust 

temperatures of more than 100 °F under 

even very light-load conditions allowing 

the NOX adsorber catalyst to function 

under these normally cold exhaust 

conditions.39 Similarly, PSA Peugeot 

Citroen (PSA) has demonstrated 

effective CDPF regeneration under 

demanding light-load taxi cab 

conditions with current production 

technologies. 40 Both of these are 

examples of technology paths available 

to nonroad engine manufacturers to 

increase temperatures under light-load 

conditions. 

While a number of commenters 

expressed concerns about low 

temperature operation for nonroad 

equipment, no commenters provided 

data showing that nonroad equipment 

in-use operating cycles would be more 

demanding of low temperature 

39 Sasaki, S., Ito, T., and Iguchi, S., ‘‘Smoke-less 

Rich Combustion by Low Temperature Oxidation in 

Diesel Engines,’’ 9th Aachener Kolloquim 

Fahrzeug—und Motorentechnik 2000. Copy 

available in EPA Air Docket A–2001–28 Item II–A– 

56. 

40 Jeuland, N., et al., ‘‘Performances and 

Durability of DPF (Diesel Particulate Filter) Tested 

on a Fleet of Peugeot 607 Taxis First and Second 

Test Phases Results,’’ October 2002, SAE 2002–01– 

2790. 

performance than passenger car urban 

driving. Both the Toyota and PSA 

systems are designed to function even 

with extended idle operation as would 

be typified by a taxi waiting to pick up 

a fare. 

It is our conclusion that by actively 

managing exhaust temperatures, for 

example through engine management to 

increase exhaust temperatures, engine 

manufacturers can ensure highly 

effective catalyst-based emission control 

performance (i.e., compliance with the 

emission standards across the 

applicable tests) and reliable filter 

regeneration across a wide range of 

engine operation as would be typified 

by the broad range of in-use nonroad 

duty cycles. Active methods of 

regenerating PM filters have been shown 

to be reliable under all operating 

conditions and can be applied to 

nonroad diesel engines in the time 

frame required by these regulations. The 

additional cost for active regeneration, 

beyond the cost for the PM filter alone, 

has been accounted for in the cost 

analysis summarized in section VI of 

this preamble. 

We have conducted an analysis of 

various nonroad equipment operating 

cycles and various nonroad engine 

power density levels to better 

understand the matching of nonroad 

engine exhaust temperatures, catalyst 

installation locations and catalyst 

technologies. This analysis, documented 

in the RIA, shows that for many engine 

power density levels and equipment 

operating cycles, exhaust temperatures 

are quite well matched to catalyst 

temperature window characteristics. In 

particular, the nonroad transient cycle 

(NRTC), the cycle we are finalizing to 

use for certification for most engines 

with rated power less than 750 hp, was 

shown to be well matched to the NOX 

adsorber characteristics with estimated 

performance in excess of 90 percent for 

a turbocharged diesel engine tested 

under a range of power density levels. 

The analysis also indicated that the 

exhaust temperatures experienced over 

the NRTC are better matched to the NOX 

adsorber catalyst temperature window 

than the temperatures that would be 

expected over the highway FTP test 

cycle. This suggests (when coupled with 

the fact that PM filters function with 

equal effectiveness at essentially all 

conditions) that compliance based on 

testing with the nonroad Tier 4 

standards on the NRTC will be 

somewhat easier, using similar 

technology, than complying with the 

highway 2007 emission standards on 

the highway transient test cycle. 

In sum, we believe based on our 

analysis of nonroad engines and 

equipment operating characteristics, 

that, in use, some nonroad engines will 

experience conditions that require the 

use of temperature management 

strategies (e.g., active regeneration) in 

order to effectively use the NOX 

adsorber and CDPF systems. We have 

assumed in our cost analysis that all 

nonroad engines complying with a PM 

standard of 0.03 g/bhp-hr or lower will 

have an active means to control 

temperature (i.e. we have costed a 

backup regeneration system, although 

some applications likely may not need 

one). We have made this assumption 

believing, as indicated by a number of 

commenters, that manufacturers will 

not be able to accurately predict in-use 

conditions for every piece of equipment 

and will thus choose to provide the 

technologies on a back-up basis. As 

explained earlier, the technologies 

necessary to accomplish this 

temperature management are 

enhancements of both the Tier 3 

emission control technologies that will 

form the starting point for Tier 4 engines 

larger than 50 hp, and the control 

strategies being developed for highway 

diesel engines.41 Based on our analyses, 

we believe that there are no nonroad 

engine applications above 25 

horsepower for which these highway 

engine approaches for temperature 

management will not work. However, 

we agree with commenters that given 

the diversity in nonroad equipment 

design and application, additional time 

will be needed in order to match the 

engine performance characteristics to 

the full range of nonroad equipment. 

We have concluded that, given the 

timing of the emissions standards 

finalized today, and the availability and 

continuing development of technologies 

to address temperature management for 

highway engines which technologies are 

transferrable to all nonroad engines with 

greater than 25 hp power rating, 

nonroad engines can be designed to 

meet the new standards in the lead time 

provided, and can be provided to 

equipment makers in a timely manner 

within that lead time. 

b. Nonroad Operating Conditions and 

Durability 

Nonroad equipment is designed to be 

used in a wide range of tasks, from 

mining equipment to crop cultivation 

and harvesting to excavation and 

41 We do not have Tier 3 emission standards for 

engines in the horsepower category from 25–50 hp. 

However, we expect that similar Tier 3 emission 

control technologies will form part of the emission 

control technology package used for compliance 

with the Tier 4 standards for these engines in 2013. 

Our cost analysis reflects the additional cost to 

apply these technologies for NOX and PM control. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38985 

loading, and operated in harsh 

environments. In the normal course of 

equipment operation the engine and its 

associated hardware will experience 

levels of vibration, impacts, and dust 

that may exceed conditions typical of 

highway diesel vehicles. For this reason, 

some commenters said that the PM filter 

technology was infeasible for nonroad 

equipment. We disagree with this 

assertion and continue to believe that 

PM filter technologies can be applied to 

a wide range of nonroad equipment. 

Specific efforts to design for the 

nonroad operating conditions will be 

required in order to ensure that the 

benefits of these new emission control 

technologies are realized for the life of 

nonroad equipment. Much of the 

engineering knowledge and experience 

to address these issues already exists 

with the nonroad equipment 

manufacturers. Vibration and impact 

issues are fundamentally mechanical 

durability concerns (rather than issues 

of technical feasibility of achieving 

emissions reductions) for any 

component mounted on a piece of 

equipment (e.g., an engine coolant 

overflow tank). Equipment 

manufacturers must design mounting 

hardware such as flanges, brackets, and 

bolts to support the new component 

without failure. Further, the catalyst 

substrate material itself must be able to 

withstand the conditions encountered 

on nonroad equipment without itself 

cracking or failing. There is a large body 

of real world testing with retrofit 

emission control technologies on 

engines up to 750 hp that demonstrate 

the durability of the catalyst 

components themselves even in the 

harshest of nonroad equipment 

applications. The evidence for even 

larger engines (i.e., those above 750 hp) 

is less conclusive because of the limited 

number of applications. 

Deutz, a nonroad engine 

manufacturer, sold approximately 2,000 

diesel particulate filter systems for 

nonroad equipment in the period from 

1994 through 2000. The very largest of 

these systems were limited to engine 

sizes below 850 hp. The majority of 

these systems were sold into 

significantly smaller applications. Many 

of these systems were sold for use in 

mining equipment. Mining equipment is 

exposed to extraordinarily high levels of 

vibration, experiences impacts with the 

mine walls and face, and encounters 

high levels of dust. Yet in meetings with 

the Agency, Deutz shared their 

experience that no system had failed 

due to mechanical failure of the catalyst 

or catalyst housing.42 The Deutz system 

utilized a conventional cordierite PM 

filter substrate as is commonly used for 

heavy-duty highway truck CDPF 

systems. The canning and mounting of 

the system was a Deutz design. Deutz 

was able to design the catalyst housing 

and mounting in such a way as to 

protect the catalyst from the harsh 

environment as evidenced by its 

excellent record of reliable function. 

A number of commenters asserted 

that it was not possible to apply 

conventional CDPF technologies (i.e., 

ceramic wall-flow filter media) to the 

largest diesel engines with power 

ratings above 750 hp. In the draft RIA 

for the proposal, we described our 

expectation that these highway-based 

systems could be assembled into larger 

systems to work well for these largest 

diesel engines. While we continue to 

believe that it may be possible in the 

time frame of this rulemaking for these 

conventional CDPFs to be applied to 

engines with more than 750 hp, based 

on the evidence provided by the 

commenters, we now agree that too 

much uncertainty remains for us to 

reach that conclusion today. We cannot 

clearly today describe a method to 

monitor the soot loading of individual 

filter elements in a parallel system made 

up of a significant number of smaller 

components. This is because for parallel 

systems the pressure drop (the best 

current method to monitor filter 

condition) across all of the parallel 

components is exactly the same. If a 

single filter begins to plug and needs to 

be regenerated it may not be detected in 

such a system. Therefore, we believe 

that instead of a massively parallel filter 

system, an alternate PM filtering media 

may be more appropriate in order to 

address issues of scalability, durability 

and packaging for these largest engines. 

Fortunately, there are other filter media 

technologies (e.g., wire or fiber mesh 

depth filters) that can be successfully 

scaled to any size and which we have 

confidence in projecting today will be a 

more appropriate solution for the bulk 

of the engines in this size category. 

Because these depth filtration 

technologies are not quite as efficient at 

filtering PM as the ceramic systems that 

are the dominant solution for the 

smaller highway diesel engines, we are 

finalizing a set of PM filter-based 

standards for engines greater than 750 

hp which are slightly higher than the 

proposed PM standards for these 

42 ‘‘Summary of Conference Call between U.S. 

EPA and Deutz Corporation on September 19, 2002 

regarding Deutz Diesel Particulate Filter System’’, 

EPA Memorandum to Air Docket A–2001–28 Item 

II–B–31. 

engines. Those standards are discussed 

in sections II.A and II.B.3 below. Our 

cost estimates summarized in section VI 

for engines greater than 750 hp are 

consistent with the use of either silicon 

carbide or wire mesh PM filter 

technologies. 

Certain nonroad applications, 

including some forms of harvesting 

equipment, consumer lawn and garden 

equipment, and mining equipment, may 

have specific limits on maximum 

surface temperature for equipment 

components in order to ensure that the 

components do not serve as ignition 

sources for flammable dust particles 

(e.g., coal dust or fine crop/lawn dust). 

Some commenters have raised concerns 

that these design constraints might limit 

the equipment manufacturers ability to 

install advanced diesel catalyst 

technologies such as NOX adsorbers and 

CDPFs. This concern seems to be largely 

based upon anecdotal experience with 

gasoline catalyst technologies where 

under certain circumstances catalyst 

temperatures can exceed 1,000 °C and 

without appropriate design 

considerations could conceivably serve 

as an ignition source. We do not believe 

that these concerns are justified in the 

case of either the NOX adsorber catalyst 

or the CDPF technology. Catalyst 

temperatures for NOX adsorbers and 

CDPFs should not exceed the maximum 

exhaust manifold temperatures already 

commonly experienced by diesel 

engines (i.e., catalyst temperatures are 

expected to be below 800 °C).43 CDPF 

temperatures are not expected to exceed 

approximately 700 °C in normal use and 

are expected to only reach the 650 °C 

temperature during periods of active 

regeneration. Similarly, NOX adsorber 

catalyst temperatures are not expected 

to exceed 700 °C and again only during 

periods of active sulfur regeneration as 

described in section III.C below. Under 

conditions where diesel exhaust 

temperatures are naturally as high as 

650 °C, no supplemental heat addition 

from the emission control system will 

be necessary for regeneration and 

therefore exhaust temperatures will not 

exceed their natural level. When natural 

exhaust temperatures are too low for 

effective emission system regeneration 

43 The hottest surface on a diesel engine is 

typically the exhaust manifold which connects the 

engines exhaust ports to the inlet of the 

turbocharger. The hot exhaust gases leave the 

engine at a very high temperature (800 °C at high 

power conditions) and then pass through the 

turbocharger where the gases expand driving the 

turbocharger providing work. The process of 

extracting work from the hot gases cools the exhaust 

gases. The exhaust leaving the turbocharger and 

entering the catalyst and the remaining pieces of the 

exhaust system is cooler (as much as 200 °C at very 

high loads) than in the exhaust manifold. 
38986 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

then supplemental heating, as described 

earlier, may be necessary but would not 

be expected to produce temperatures 

higher than the maximum levels 

normally encountered in diesel exhaust. 

Furthermore, even if it were necessary 

to raise exhaust temperatures to a higher 

level in order to promote effective 

emission control, there are technologies 

available to isolate the higher exhaust 

temperatures from flammable materials 

such as dust. One approach would be 

the use of air-gapped exhaust systems 

(i.e., an exhaust pipe inside another 

concentric exhaust pipe separated by an 

air-gap) that serve to insulate the inner 

high temperature surface from the outer 

surface which could come into contact 

with the dust. The use of such a system 

also may be desirable in order to 

maintain higher exhaust temperatures 

inside the catalyst in order to promote 

better catalyst function. Another 

technology to control surface 

temperature already used by some 

nonroad equipment manufacturers is 

water cooled exhaust systems.44 This 

approach is similar to the air-gapped 

system but uses engine coolant water to 

actively cool the exhaust system. 

We thus do not believe that 

flammable dust concerns will prevent 

the use of either a NOX adsorber or a 

CDPF because catalyst temperatures are 

not expected to be unacceptably high 

and because remediation technologies 

exist to address these concerns. In fact, 

exhaust emission control technologies 

(i.e., aftertreatment) have already been 

applied on both an original equipment 

manufacturer (OEM) basis and for 

retrofit to nonroad equipment for use in 

potentially explosive environments. 

Many of these applications must 

undergo Underwriters Laboratory (UL) 

approval before they can be used.45 

Therefore, while we appreciate the 

commenters’ concerns regarding safety, 

we remain convinced that the 

application of these emission control 

technologies will not compromise (or 

decrease) equipment safety. 

We agree that nonroad equipment 

must be designed to address safety and 

durable performance for a wide range of 

operating conditions and applications 

44 ‘‘Engine Technology and Application Aspects 

for Earthmoving Machines and Mobile Cranes,’’ Dr. 

E. Brucker, Liebherr Machines Bulle, SA, AVL 

International Commercial Powertrain Conference, 

October 2001. Copy available in EPA Air Docket A– 

2001–28, Docket Item # II–A–12. 

45 Phone conversation between Byron Bunker, 

United States Environmental Protection Agency and 

Dale McKinnon, Manufacturers of Emission Control 

Association (MECA), 9 April, 2003 confirming the 

use of emission control technologies on nonroad 

equipment used in coal mines, refineries, and other 

locations where explosion proofing may be 

required. 

that would not commonly be 

experienced by highway vehicles. We 

believe further as demonstrated by 

retrofit experiences around the world 

that technical solutions exist which 

allow catalyst-based emission control 

technologies to be applied to nonroad 

equipment. 

2. Are the Standards for Engines 75–750 

hp Feasible? 

There are three primary test 

provisions and associated standards in 

the Tier 4 program we are finalizing 

today. These are the Nonroad Transient 

Cycle (NRTC), the existing International 

Organization for Standardization (ISO) 

C1 steady-state cycle, and the highwaybased Not-To-Exceed (NTE) 

provisions.46 Under today’s rules, most 

nonroad diesel engines must meet the 

new standards for each of these three 

test cycles (the exceptions are noted 

below). Compliance on the transient test 

cycle includes weighting the results 

from a cold start and hot start test with 

the cold start emissions weighted at 1/ 

20 and hot start emissions weighted at 

19/20. Additionally, we have alternative 

optional test cycles including the 

existing ISO–D2 steady-state cycle and 

the Transportation Refrigeration Unit 

(TRU) cycle which a manufacturer can 

choose to use for certification in lieu of 

the NRTC and the ISO–C1, provided 

that the manufacturer can demonstrate 

to the Agency that the engine will only 

be used in a limited range of nonroad 

equipment with known operating 

conditions. A complete discussion of 

these various test cycles can be found in 

chapter 4.2, 4.3, and 4.4 of the RIA. 

The standards we are finalizing today 

for nonroad engines with rated power 

from 75 to 750 hp are based upon the 

performance of technologies and 

standards for highway diesel engines 

which go into effect in 2007. As 

explained above, we believe these 

technologies, namely NOX adsorbers 

and catalyzed diesel particulate filters 

enabled by 15 ppm sulfur diesel fuel, 

can be applied to nonroad diesel 

engines in a similar manner as for 

highway diesel engines. The 

combustion process and the means to 

modify that process are fundamentally 

the same for highway and nonroad 

diesel engines regardless of engine size. 

The formation mechanism and quantity 

of pollutants formed in diesel engines 

are fundamental characteristics of 

engine design and are not inherently 

different for highway and nonroad 

46 As an alternative to compliance with the ISO 

C1 test procedure, a manufacturer can show 

compliance with the standards by testing over the 

Ramped Modal Cycle (RMC) as described in section 

III.F. 

engines regardless of engine size. The 

effectiveness of NOX adsorbers to 

control NOX emissions and CDPFs to 

control PM, NMHC, and CO emissions 

are determined by fundamental catalyst 

and filter characteristics. Therefore, we 

disagree with commenters who suggest 

that these highway technology based 

emission standards are infeasible for 

nonroad engines. We acknowledge the 

comments raised regarding the unique 

characteristics nonroad diesel engines 

which must be considered in setting 

these standards, and we have addressed 

those issues by allowing (where 

appropriate) for additional lead time or 

slightly less stringent standards for 

nonroad diesel engines in comparison to 

highway diesel engines (and likewise 

have made appropriate cost estimates to 

account for the technology and 

engineering needed to address these 

issues). 

PM Standard. We are finalizing a PM 

standard for engines in this category of 

0.01 g/bhp-hr based upon the emissions 

reductions possible through the 

application of a CDPF and 15 ppm 

sulfur diesel fuel. This is the same 

emissions level as for highway diesel 

engines in the heavy-duty 2007 

(HD2007) program (66 FR 5001, January 

18, 2001). While emission levels of 

engine-out soot (the solid carbon 

fraction of PM) may be somewhat higher 

for some nonroad engines when 

compared to highway engines, these 

emissions are virtually eliminated 

(reduced by 99 percent) by the CDPF 

technology. With application of the 

CDPF technology, the soluble organic 

fraction (SOF) portion of diesel PM is 

predicted to be all but eliminated. The 

primary emissions from a CDPF 

equipped engine are sulfate PM 

emissions formed from sulfur in diesel 

fuel. The emissions rate for sulfate PM 

is determined primarily by the sulfur 

level of the diesel fuel and the rate of 

fuel consumption. With the 15 ppm 

sulfur diesel fuel, the PM emissions 

level from a CDPF equipped nonroad 

diesel engine will be similar to the 

emissions rate of a comparable highway 

diesel engine. Therefore, the 0.01 g/bhphr emission level is feasible for nonroad 

engines tested on the NRTC cycle and 

on the steady-state cycles, ISO–C1 and 

ISO–D2. Put another way, control of PM 

using CDPF technology is essentially 

independent of duty cycle given active 

catalyst technology (for reliable 

regeneration and SOF oxidation), 

adequate control of temperature (for 

reliable regeneration) and low sulfur 

diesel fuel (for reliable regeneration and 

low PM emissions). While some 

commenters argued that PM filters will 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38987 

not enable the 0.01 PM emission 

standard for nonroad engines, we 

remain convinced by the demonstration 

of 0.01 or lower PM emission levels 

from a number of diesel engines 

described in the RIA, that the standard 

is feasible given the leadtime provided 

and the availability of 15 ppm sulfur 

diesel fuel. Likewise, the NTE 

provisions for nonroad engines are the 

same as for on-highway engines meeting 

an equivalent PM control level. The 

maximum PM emission level from a 

CDPF equipped diesel engine is 

primarily determined by the maximum 

fuel sulfur conversion level experienced 

at the highest operating conditions. As 

documented in RIA chapter 4.1.1.3, 

testing of diesel engines at conditions 

representative of the highest sulfate PM 

formation rates shows PM levels below 

the level required by the NTE provisions 

when tested on less than 15 ppm sulfur 

diesel fuel. 

NOX Standard. We are finalizing a 

NOX standard of 0.30 g/bhp-hr for 

engines in this category based upon the 

emission reductions possible from the 

application of NOX adsorber catalysts 

and the expected emission levels for 

Tier 3 compliant engines which form 

the baseline technology for Tier 4 

engines. The Tier 3 emission standards 

are a combined NMHC+NOX standard of 

3.0 g/bhp-hr for engines greater than 100 

hp and less than 750 horsepower. For 

engines less than 100 hp but greater 

than 50 horsepower the Tier 3 

NMHC+NOX emission standard is 3.5 g/ 

bhp-hr. We believe that in the timeframe of the Tier 4 emission standards, 

all engines from 75 to 750 hp can be 

developed to control NOX emissions to 

engine-out levels of 3.0 g/bhp-hr or 

lower.47 This means that all engines will 

need to apply Tier 3 emission control 

technologies (i.e., turbochargers, chargeair-coolers, electronic fuel systems, and 

for some manufacturers EGR systems) to 

get to this baseline level. As discussed 

in more detail in the RIA, our analysis 

of the NRTC and the ISO–C1 cycles 

indicates that the NOX adsorber catalyst 

can provide a 90 percent or greater NOX 

reduction level on the cycles. The 

standard of 0.30 g/bhp-hr reflects a 

baseline emissions level of 3.0 g/bhp-hr 

and a greater than 90 percent reduction 

of NOX emissions through the 

application of the NOX adsorber 

catalyst. The additional lead time 

available to nonroad engine 

manufacturers and the substantial 

47 For engines between 75 and 100 horsepower, 

this may require re-optimization of the engine to 

lower NOX emissions if they are higher than 3.0, but 

we would not expect any new hardware beyond the 

Tier 3 hardware to be required in the Tier 4 

timeframe to accomplish this reduction. 

learning that will be realized from the 

introduction of these same technologies 

to highway diesel engines, plus the lack 

of any fundamental technical 

impediment, makes us confident that 

the new NOX standards can be met. 

Given the fundamental similarities 

between highway and nonroad diesel 

engines, we believe that the NOX 

adsorber technology developed for 

highway engines can be applied with 

equal effectiveness to nonroad diesel 

engines with additional developments 

in engine thermal management (as 

discussed in section II.B.2 above) to 

address the more widely varied nonroad 

operating cycles. In fact, as discussed 

previously, the NOX adsorber catalyst 

temperature window is particularly well 

matched to transient operating 

conditions as typified by the NRTC. 

As pointed out by some commenters, 

compliance with the NTE provisions 

will be challenging for the nonroad 

engine industry due to the diversity of 

nonroad products and operating cycles. 

However, the technical challenge is 

reduced somewhat by the 1.5 multiplier 

used to calculate the NTE standard as 

discussed in section III.J. Controlling 

NOX emissions under NTE conditions is 

fundamentally similar for both highway 

and nonroad engines. The range of 

control is the same and the amount of 

reduction required is also the same. We 

know of no technical impediment, nor 

were any raised by commenters, that 

would prevent achieving the NTE 

standard under the zone of operating 

conditions required by the NTE. 

NMHC Standard. Meeting the NMHC 

standard under the lean operating 

conditions typical of the biggest portion 

of NOX adsorber operation should not 

present any special challenges to 

nonroad diesel engine manufacturers. 

Since CDPFs and NOX adsorbers contain 

platinum and other precious metals to 

oxidize NO to NO2, they are also very 

efficient oxidizers of hydrocarbons. 

NMHC reductions of greater than 95 

percent have been shown over transient 

and steady-state test procedures.48 

Given that typical engine-out NMHC is 

expected to be in the 0.40 g/bhp-hr 

range or lower for engines meeting the 

Tier 3 standards, this level of NMHC 

reduction will mean that under lean 

conditions emission levels will be well 

below the standard. For the same 

reasons, there is no obstacle which 

48 ‘‘The Impact of Sulfur in Diesel Fuel on 

Catalyst Emission Control Technology,’’ report by 

the Manufacturers of Emission Controls 

Association, March 15, 1999, pp. 9 & 11. Copy 

available in EPA Air Docket A–2001–28 Item II–A– 

67. 

would prevent achieving the NTE 

standard. 

Under the brief episodic periods of 

rich operation necessary to regenerate 

NOX adsorber catalysts, it is possible to 

briefly experience higher levels of 

NMHC emissions. Absent a controlling 

standard, it is possible that these NMHC 

emissions could be high. There are two 

possible means to control the NMHC 

emissions during these periods in order 

to meet the NMHC standard finalized 

today. Manufacturers can design the 

regeneration system and the oxygen 

storage (oxidation function under rich 

conditions) of the NOX adsorber catalyst 

such that the NMHC emissions are 

inherently controlled. This is similar to 

the control realized on today’s threeway automotive catalysts which also 

experience operation that toggles 

between rich and lean conditions. 

Secondly, a downstream clean-up 

catalyst can be used to oxidize the 

excess NMHC emissions to a level 

below the standard. This approach has 

been used in the NOX adsorber 

demonstration program at EPA 

described in the RIA. Our cost analysis 

for engines in the 75 to 750 hp category 

includes a cost for a clean-up catalyst to 

perform this function. 

Cold Start. The standards include a 

cold start provision for the NRTC 

procedure. This means that the results 

of a cold start transient test will be 

weighted with the emissions of a hot 

start test in order to calculate the 

emissions for compliance against the 

standards. In a change from the 

proposed rule, the weightings are 1/20 

cold start and 19/20 for the hot start (as 

opposed to the proposed weightings of 

1/10 and 9/10, respectively) as 

described more fully in chapter 4.2 of 

the RIA and section III.F below. Because 

exhaust temperatures are so important 

to catalyst performance, a cold start 

provision is an important tool to ensure 

that the emissions realized in use are 

consistent with the expectations of this 

program. Achieving this standard 

represents an additional technical 

challenge for NOX control and to a 

lesser extent CO and NMHC control 

(i.e., control of gaseous pollutants). PM 

control with a CDPF is not expected to 

be significantly impacted by cold-start 

provisions due to the primary filter 

mechanism being largely unaffected by 

temperature. 

With respect to achievability of the 

NOX, CO and NMHC standards, during 

the initial start and warmup period for 

a diesel engine, the exhaust 

temperatures are typically below the 

light-off temperature of a catalyst. As a 

result, exhaust stack emissions may 

initially be higher during this period of 
38988 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

operation. The cold start test procedure 

is designed to quantify these emissions 

to ensure that emission control systems 

are designed appropriately to minimize 

the contribution of cold-start emissions. 

Cold-start emissions can be minimized 

by improving catalyst technology to 

allow for control at lower exhaust 

temperatures (i.e., by lowering the 

catalyst light-off temperature) and by 

applying strategies to quickly raise the 

exhaust temperature to a level above the 

catalyst light-off temperature. 

There are a number of technologies 

available to the engine manufacturer to 

promote rapid warmup of the exhaust 

and emission control system. These 

include retarding injection timing, 

increasing EGR, and potentially late 

cycle injection, all of which are 

technologies we expect manufacturers 

to apply as part of the normal operation 

of the NOX adsorber catalyst system. 

These are the same technologies we 

expect highway engine manufacturers to 

use in order to comply with the 

highway cold start FTP provision which 

weights cold start emissions more 

heavily with a 1/7 weighting. As a 

result, we expect the transfer of highway 

technology to be well matched to 

accomplish this control need for 

nonroad engines as well. Using these 

technologies we expect nonroad engine 

manufacturers to be able to comply with 

the new Tier 4 NOX, CO, and NMHC 

emission standards including the cold 

start provisions of the transient test 

procedure. 

One commenter has raised the 

concern that if diesel engines are no 

cleaner than 3 g/bhp-hr NOX and if NOX 

adsorbers can be no more efficient than 

90 percent, then any increase in NOX 

emissions above the 0.30 g/bhp-hr level 

on a cold-start test will make the 

emission standards infeasible. We 

should clarify, when discussing the 

emission reduction potential of the NOX 

adsorber catalyst generically in the 

NPRM, we have sometimes simply 

stated that it is 90 percent or more 

effective without plainly saying that this 

refers to our expectation for average 

performance considering both cold and 

hot start emissions. More precisely then, 

we would expect lower effectiveness 

over the cold-start test procedure with 

somewhat higher effectiveness realized 

over the hot-start test procedure. 

Because of the relative weightings of the 

two test cycles (i.e., 1/20 for the coldstart and 19/20 for the hot-start), 

although the degradation of 

performance below 90 percent over the 

cold-start cycle can be substantially 

greater than the performance above 90 

percent realized over the hot-start cycle, 

the standards remain feasible. For 

example, even if the average NOX 

adsorber performance over the cold-start 

test cycle was only 70 percent, the 

average NOX adsorber performance over 

the hot-start portion of the test cycle 

would only need to be 91 percent in 

order to realize a weighted average 

performance of 90 percent. Similarly, 

were the cold-start test cycle 

performance only 50 percent, the hotstart performance would only need to be 

92 percent in order to realize a weighted 

average performance of 90 percent.49 

We are confident, based on our 

estimates of NOX adsorber performance 

over the nonroad test cycle summarized 

in the RIA, that NOX adsorber 

performance in excess of 92 percent can 

be expected in the time frame of the 

requirements finalized today. 

Complying with the PM standard 

given consideration of the cold start test 

procedure is not expected to be as 

challenging as compliance with the NOX 

standard. The effectiveness for PM 

filtration is not significantly effected by 

exhaust temperatures, as noted earlier. 

Thus, PM emission levels are similar 

over the cold and hot start tests. 

The standards that we are finalizing 

today for nonroad engines with rated 

horsepower levels from 75 to 750 hp are 

based upon the same emission control 

technologies, clean 15 ppm or lower 

sulfur diesel fuel, and relative levels of 

emission control effectiveness as the HD 

2007 emission standards. We have given 

consideration to the diversity of 

nonroad equipment for which these 

technologies must be developed and the 

timing of the Tier 3 emissions standards 

in determining the appropriate timing 

for the Tier 4 standards. Based upon the 

availability of the emission control 

technologies, the proven effectiveness of 

the technologies to control diesel 

emissions to these levels, the technology 

paths identified here to address 

constraints specific to nonroad 

equipment, and the additional lead time 

afforded by the timing of the standards, 

we have concluded that the standards 

are technically feasible in the leadtime 

provided. 

3. Are the Standards for Engines Above 

750 hp Feasible? 

The preceding discussion of the 

standards for engines of 75 to 750 hp 

highlights the main thrust of our new 

Tier 4 program, a focus on realizing very 

low on-highway like emission levels for 

the vast majority of nonroad diesel 

engines. The emission standards and the 

49 The combined weighted average performance is 

calculated as 1/20 (cold-start) + 19/20 (hot-start). 

Hence it can be seen that 1/20 (70%) + 19/20 (91%) 

= 90% and likewise that 1/20 (50%) + 19/20 (92%) 

= 90%. 

combination of technologies that we 

expect will be used to meet those 

standards are virtually identical to the 

HD2007 program for on-highway 

engines. The following three sections 

(II.B.3, II.B.4, and II.B.5) describing the 

feasibility of the standards for engines 

above 750 hp, from 25 to 75 hp, and 

below 25 hp, while following the same 

pattern and objective, take additional 

consideration of the fact that engines 

and equipment in these size categories 

have no direct on-highway equivalent 

and differ from highway engines in 

substantial ways that cause us to reach 

differing conclusions regarding the 

appropriate standards and timing for 

those standards. Whether in scale, or 

use, or operating conditions, the 

characteristics of these engines and 

equipment are such that we have taken 

particular consideration of them in 

setting the timing and level of the 

standards. The remainder of this section 

(II.B.3) discusses what makes the above 

750 hp category unique and why the 

standards which we are adopting are 

technologically feasible. 

a. What Makes the Over 750 hp Category 

Different? 

The first and most obvious difference 

for engines in this horsepower category 

is scale. No on-highway engines come 

close to the size of the largest engines 

in this category which can produce in 

excess of 3,000 horsepower, consist of 

16 or more cylinders and have 12 or 

more turbochargers. The engines, and 

the equipment that they power, are 

quite simply significantly larger than 

any on-highway diesel engine. Many 

commenters argued that emission 

technologies from on-highway vehicles 

could not be simply scaled up for these 

larger engines and that if they were, the 

consequences of this resizing would 

include structural weakness and 

reduced system robustness. As 

discussed below, our review of the 

information provided with these 

comments and our subsequent analysis 

of the technical characteristics of some 

emission control components has led us 

to conclude that revised emission 

standards (based on performance of 

different technologies that those whose 

performance formed the basis for the 

proposed rule) from those we proposed 

for this horsepower category are 

appropriate and available. 

We have concluded that it is 

appropriate to distinguish between two 

broad categories of engines over 750 hp 

grouped by application: Mobile 

machines and generator sets. Mobile 

machines include the very largest 

nonroad equipment used in mining 

trucks and large excavation equipment. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38989 

The environment and operating 

conditions (especially for vibration) 

represent the harshest application into 

which nonroad engines are applied. 

Design considerations for technologies 

used to control emissions from engines 

in these applications must first consider 

robustness to the harsh environments 

that will be experienced in use. In 

contrast, mobile nonroad generator sets 

operate in relatively good operating 

environments. In addition, while mobile 

nonroad generator sets can, and are 

moved between operating locations, 

they are always stationary during actual 

operation. Thus the levels of vibration 

and the general environment for engine 

operation are significantly less 

demanding for generator sets than for 

mobile machines. Also the dynamic 

range of operation is significantly 

narrower and less demanding for 

generator sets. Designed to operate at a 

set engine speed, synchronous to the 

frequency cycle desired for electric 

generation (i.e., 1200 or 1800 RPM for 

60 hz), diesel engines designed for 

generator set applications can be 

optimized for operation in this narrow 

range. 

We have given specific consideration 

to the unique engineering challenges for 

engines in this horsepower category in 

determining the appropriate emission 

standards set in today’s action. We have 

also taken into account the important 

differences between generator set 

applications and other mobile 

applications in developing standards for 

this horsepower category. 

b. Are the New Tier 4 Standards for 

Over 750 hp Engines Technologically 

Feasible? 

The emission standards described in 

section II.A above describe a 

comprehensive program for engines 

over 750 hp that give consideration to 

both the physical size of these engines 

and the applications into which these 

engines are applied. Engines in this 

power category must show compliance 

with the C1 or D2 steady-state test 

cycles as appropriate as well as with the 

NTE provisions finalized today. As 

described in sections III.F and III.G, 

these engines will not be tested over the 

NRTC nor will they be subject to a coldstart test procedure. The feasibility 

discussion in this section describes 

expected performance of the engines 

over the required test cycles and the 

NTE. This section will briefly 

summarize the feasibility analysis 

contained in the RIA for these engines. 

PM Standards. Beginning in 2011 all 

nonroad diesel engines above 750 hp 

must meet a PM standard of 0.075 g/ 

bhp-hr. We believe that this PM 

standard is feasible based on the 

substantial reductions in sulfate PM due 

to the use of 15 ppm sulfur diesel fuel 

and the potential to improve the 

combustion process to reduce PM 

emissions formed in the engine. 

Specifically, we believe based on the 

evidence in the RIA that increasing fuel 

injection pressure, improving electronic 

controls and optimizing the combustion 

system geometry will allow engine 

manufacturers to meet this level of PM 

control in 2011. Some engine 

manufacturers have in fact indicated to 

the Agency that this level of control 

represents an achievable goal by 2011. 

One commenter argued however, that a 

more relaxed standard of 0.1 g/bhp-hr 

based on today’s on-highway diesel 

engine performance would be 

appropriate. We disagree with this 

comment, believing that given the 

substantial leadtime available and the 

potential for further improvements in 

combustion systems, that it is 

appropriate to set a forward looking PM 

standard of 0.075 g/bhp-hr. Conversely, 

other commenters argued that future onhighway PM filter technology should be 

applied to this class of engines as early 

as 2011 (i.e., that a standard of 0.01 g/ 

bhp-hr PM is appropriate). While we 

agree with the commenters that in the 

long-term it will be appropriate to apply 

filter-based emission control 

technologies to these engines, we do not 

agree that such control is appropriate as 

early as 2011. As the following section 

explains, we believe that there are 

remaining technical challenges to be 

addressed prior to the application of PM 

filters to these engines and that it is 

necessary to allow additional leadtime 

for those challenges to be addressed. 

Beginning in 2015 all nonroad 

engines over 750 hp must meet stringent 

PM filter technology-based emission 

standards of 0.02 g/bhp-hr for engines 

used in generator set applications and 

0.03 g/bhp-hr for engines used in mobile 

machine applications. We are 

predicating these emission standards 

based on the application of a different 

form of diesel particulate filter 

technology, a wire or fiber mesh depth 

filter rather than a ceramic wall flow 

filter. Wire mesh filters are capable of 

reducing PM by 70 percent or more. We 

have not based these standards upon the 

more efficient (>90 percent) control 

possible from ceramic wall flow style 

PM filters, because we believe that the 

application of the wall flow filter 

technology on engines of this size has 

not been adequately demonstrated at 

this time. While it would certainly be 

possible to apply the ceramic-based 

technology to these larger engines, we 

cannot today conclude with certainty 

that such systems would be as robust inuse as needed (see earlier discussion in 

section II.B.1.b). Considering the 

information available to the Agency 

today, we believe it appropriate to set 

the long term PM standard for these 

very large engines based on technologies 

which we can project with confidence 

will give high levels of emission 

reduction, durability, and robustness 

when scaled to these very large engine 

sizes. 

The 0.01 g/bhp-hr difference in the 

PM emission standards between the 

standard for generator sets and for other 

mobile applications in this category 

(0.01 g/bhp-hr lower for generator sets) 

reflects our expectation that engine-out 

emissions from generator sets can be 

reduced below the level for mobile 

machines due to generator set operation 

at a single engine speed. Without the 

need to provide full power and control 

over the wider range of possible 

operating conditions that mobile 

machines must deliver, we believe that 

the air handling systems (especially the 

turbocharger match to the engine) can 

be improved to provide a moderate 

reduction in engine-out emissions. This, 

coupled with the reduction afforded by 

the PM filter technology, would allow 

generator sets to meet a more stringent 

0.02 g/bhp-hr standard. Diesel engines 

designed for use in generator sets 

meeting this standard will need to 

demonstrate compliance over the 

appropriate test cycles, either the ISO 

C1 or D2 tests. As discussed in RIA 

chapter 4.3.6.2, PM emission rates are 

nearly the same for steady-state testing 

or for alternative ramped modal cycle 

(RMC) testing. These test cycles, like the 

engines, are designed to be 

representative of the range of operation 

expected from a generator set. 

As discussed previously, PM emission 

control over the NTE region for PM filter 

equipped diesel engines is 

predominantly a function of sulfate 

formation at high exhaust temperatures. 

Given that fuel consumption (and thus 

sulfur) consumption rates on a brake 

specific basis tend to be lower for 

engines above 750 hp, we can conclude 

that the increase in PM emissions over 

the NTE region will likely be lower for 

these engines than for engines meeting 

the 0.01 g/bhp-hr standard. Thus, we 

can conclude based on the evidence in 

the RIA that compliance with the NTE 

provisions for PM is feasible for engines 

over 750 hp. 

Although we are projecting that 

manufacturers will comply with this 

standard using a slightly less efficient 

PM filter technology, we remain 

convinced that 15 ppm sulfur diesel fuel 
38990 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

will still be a necessity for this 

technology to be applied. Regardless of 

the filter media chosen for the PM filter, 

the filter will still require catalyst-based 

systems to ensure robust regeneration 

and adequate control of the SOF portion 

of PM. As these catalyst-based 

technologies are adversely impacted by 

sulfur in diesel fuel as described in II.C 

below, 15 ppm sulfur diesel fuel will be 

required in order to ensure compliance 

with the PM standards finalized here for 

engines over 750 hp. 

NOX Standards. As with the PM 

standards, we are setting distinct NOX 

standards for this category of engines 

reflecting particular concerns with the 

application of technologies to engines of 

this size and our desire to realize 

significant NOX reductions as soon as 

possible. There are two sets of NOX 

standards that we are finalizing today, a 

0.50 g/bhp-hr NOX standard for engines 

used in generator set applications and a 

2.6 g/bhp-hr NOX standard for mobile 

machines. 

For engines used in generator set 

applications we are finalizing a 0.50 g/ 

bhp-hr standard that goes into effect for 

engines above 1,200 hp in 2011 and in 

2015 for engines above 750 hp. We see 

two possible technology options for 

manufacturers to meet these standards. 

First, compliance with this NOX 

standard will be possible through the 

application of a dual bed NOX adsorber 

system (i.e., a system that allows 

regeneration to be controlled external to 

the engine). This approach can work 

well for generator set applications 

where packaging constraints and 

vibration issues are greatly reduced. 

Since this approach requires limited 

engine redesign, it would be an 

appealing approach for these large 

engines sold in very low volumes. NOX 

adsorber systems for stationary power 

generation (systems that never move) 

are available today on a retrofit basis, 

and we believe with further 

development to address packaging and 

durability concerns that similar systems 

can be applied to mobile generator 

sets.50 

A second possible technology option 

for engines in this category is urea SCR. 

The challenges for urea SCR in mobile 

applications are well known, 

specifically a lack of urea infrastructure 

to provide urea refill at diesel fueling 

locations and a need to ensure that urea 

is added as necessary in use.51 These 

hurdles can be addressed more easily 

for generator sets than for virtually any 

50 Emerachem EMxTM Datasheet—Describing the 

EMx IC (Internal Combustion) System Air Docket 

OAR–2003–0012–0948. 

51 See for example 68 FR 28375, May 23, 2003. 

other mobile source emission category. 

Although nonroad generator sets are 

mobile, in operation they remain at a 

fixed location where fuel is delivered to 

them periodically (i.e., a 1,200 hp 

generator set does not and cannot pull 

into the local truck stop for a fuel fill). 

Therefore, the same infrastructure that 

currently provides urea delivery for 

stationary power generation can also be 

utilized for nonroad generator set 

applications.52 It would still remain for 

the manufacturer to develop a 

mechanism to ensure urea refill, but we 

believe it is likely that solutions to this 

problem can be addressed through 

monitoring as for stationary source 

emissions or other technology options 

(e.g., a urea interlock that precludes 

engine operation without the presence 

of urea). 

Either of these technology approaches 

could be applied to realize an 

approximately 90 percent reduction 

from the current Tier 2 emission levels 

for these engines in order to comply 

with an emission standard of 0.50 g/ 

bhp-hr. The 0.50 g/bhp-hr standard is 

different from our proposed level of 0.30 

g/bhp-hr reflecting the changes we have 

made in this final action to the 

implementation schedule for this class 

of engines and therefore our projections 

for a technology path. At the time of the 

proposal, we projected that this class of 

engine would follow an integrated twostep technology path. We are now 

finalizing a program that anticipates the 

application of 90 percent effective NOX 

control to diesel engines for use in 

generator sets without a reduction in 

engine-out NOX levels beyond Tier 2. 

This reflects our desire to focus on 

getting the largest emission reduction 

possible in the near term (beginning in 

2011) from these engines. Where we 

believe additional technology 

development is needed, as is the case 

for mobile machines over 750 hp, we are 

finalizing a more gradual emission 

reduction technology pathway 

anticipating further reductions in 

engine-out NOX emissions followed by 

a possible future action to reduce 

emissions further as described in 

section II.A. RIA chapter 4.1.2.3.3 

describes NOX adsorber effectiveness to 

control NOX emissions including 

effectiveness over the NTE region. The 

discussion there is equally applicable to 

engines above and below 750 hp 

regarding NTE performance because the 

key attribute of NTE performance 

(exhaust temperature) is similar for 

engines across the horsepower range. 

52 Fleetguard StableGuardTM Urea Premix for use 

with SCR NOX Reduction Systems, Air Docket A– 

2001–28 Item IV–A–04. 

For engines over 750 hp used in 

mobile machines (and for 750–1200 hp 

generator sets from 2011 until 2015) we 

are setting a new NOX standard of 2.6 

g/bhp-hr beginning in 2011. We are 

predicating this level of emission 

control (an approximate 50 percent 

reduction from Tier 2) on an improved 

combustion system and proven enginebased NOX control technologies. 

Specifically, we believe manufacturers 

can apply either proven cooled EGR 

technology, or apply additional levels of 

engine boost, a limited form of Miller 

Cycle operation, and increased 

intercooling capacity for the two-stage 

turbocharging systems that are used on 

these engines. The second approach for 

in-cylinder emissions reductions is 

similar in description at least to the 

Caterpillar ACERT technology which we 

believe could be another path for 

compliance with this standard. We are 

projecting a modest increase in heatrejection to the engine coolant for these 

in-cylinder emission control solutions 

and have accounted for those costs in 

our cost analysis. These approaches for 

NOX reduction have been proven for onhighway diesel engines since 2003 

including compliance with NTE 

provisions similar to those for nonroad 

engines finalized here. We can conclude 

based on the on-highway experience 

that the NTE provisions can be met for 

engines in this horsepower category. 

One commenter suggested that a 

standard of 3.5 g/bhp-hr would be 

achievable in this time frame. As 

described here, we believe that further 

emission reductions to 2.6 g/bhp-hr are 

possible in this time frame. Engine 

manufacturers have indicated to the 

Agency that they believe this level of incylinder emission control can be 

realized for these very large diesel 

engines by 2011. We are deferring any 

decision on setting aftertreatment based 

NOX standards for mobile machinery 

above 750 hp to allow additional time 

to evaluate the technical issues 

involved, as discussed in section II.A.4. 

NMHC Standards. We are setting two 

different NMHC emission standards for 

engines in this category linked to the 

technologies used to control PM 

emissions. We are requiring all engines 

over 750 hp to meet an NMHC standard 

of 0.30 g/bhp-hr starting in 2011. As 

explained earlier, in 2011 all engines 

over 750 hp must meet a PM emission 

standard of 0.075 g/bhp-hr. We are 

projecting that manufacturers will meet 

this standard through improvements in 

in-cylinder emission control of PM (in 

conjunction with use of 15 ppm sulfur 

diesel fuel). These PM control 

technologies, increased fuel injection 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38991 

pressure, improved electronic controls 

and enhanced combustion system 

designs will concurrently lower NMHC 

emissions to the NMHC standard of 0.30 

g/bhp-hr. 

The second step in our NMHC 

standards is to a level of 0.14 g/bhp-hr, 

consistent with the standard for onhighway diesels beginning in 2007 and 

for other nonroad diesel engines from 75 

to 750 hp beginning in 2011. This 

change in NMHC standards is timed to 

coincide with the requirement that 

engines over 750 hp meet stringent PM 

emission standards that we believe will 

require the use of catalyst-based diesel 

particulate filter systems. These systems 

are expected to incorporate oxidation 

catalyst functions to control the SOF 

portion of diesel PM and to promote 

robust soot regeneration within the 

filter. This same oxidation function is 

highly effective at controlling NMHC 

emissions (the RIA documents 

reductions of more than 80 percent) and 

will result in a reduction in NMHC 

emissions below the 0.14 g/bhp-hr 

standard for these engines. As the high 

level of NMHC control afforded by the 

application of this technology is broadly 

realized across the wide range of diesel 

engine operation, it will allow for 

compliance with the NTE provisions as 

well. Although in practice we expect 

that NMHC emissions may be lower 

than the 0.14 g/bhp-hr standard, we 

have not finalized a more stringent 

standard for NMHC in order to maintain 

consistency with the NMHC standard 

we are finalizing for engines from 75 hp 

to 750 hp, for which the NMHC 

standard is in part based on feasibility 

considerations for NOX adsorber catalyst 

systems that use diesel fuel to 

regenerate themselves (with consequent 

increased NMHC emissions during 

regeneration events). We believe this is 

appropriate considering our expectation 

that NOX adsorber technology will be 

found feasible for all nonroad engines 

over 750 hp. 

4. Are the New Tier 4 Standards for 

Engines 25–75 hp Feasible? 

As discussed in section II.B, our 

standards for 25–75 hp engines consist 

of a 2008 transitional standard and longterm 2013 standards. The transitional 

standard is a 0.22 g/bhp-hr PM 

standard. The 2013 standards consist of 

a 0.02 g/bhp-hr PM standard and a 3.5 

g/bhp-hr NMHC+NOX standard.53 As 

discussed in section II.A, the 

53 The 2013 NOX+NMHC standard is a new 

standard only for engines in the 25–50 hp category. 

For engines in the 50–75 hp category, 3.5 g/bhp-hr 

NOX+NMHC is the existing Tier 3 emission 

standard which will now also apply across the new 

regulated test cycles (e.g., NRTC). 

transitional standard is optional for 50– 

75 hp engines, as the 2008 

implementation date is the same as the 

effective date of the Tier 3 standards. 

Manufacturers may decide, at their 

option, not to undertake the 2008 

transitional PM standard, in which case 

their implementation date for the 0.02 g/ 

bhp-hr PM standard begins in 2012. The 

remainder of this section discusses what 

makes the 25–75 hp category unique 

and why the standards are 

technologically feasible. 

a. What Makes the 25–75 hp Category 

Unique? 

As EPA explained in the proposal, 

and as discussed in section II.A, one 

cannot assume that highway 

technologies are automatically 

transferable to 25–75 hp nonroad 

engines. In contrast with 75–750 hp 

engines, which share similarities in 

displacement, aspiration, fuel systems, 

and electronic controls with highway 

diesel engines, engines in the 25–75 hp 

category have a number of technology 

differences from the larger engines. 

These include a higher percentage of 

indirect-injection fuel systems, and a 

low fraction of turbocharged engines 

(see generally RIA chapter 4.1). The 

distinction in the under 25 hp category 

is even more pronounced, with no 

turbocharged engines, nearly one-fifth of 

the engines have two cylinders or less, 

and a significant majority of the engines 

have indirect-injection fuel systems. 

The distinction is particularly marked 

with respect to electronically controlled 

fuel systems. These are commonly 

available in the power categories greater 

than or equal to 75 hp, but, based on the 

available certification data as well as 

our discussions with engine 

manufacturers, we believe there are very 

limited numbers, if any, in the 25–75 hp 

category (and no electronic fuel systems 

in the less than 25 hp category). The 

research and development work being 

performed today for the heavy-duty 

highway market is targeted at engines 

which are 4-cylinders or more, directinjection, electronically controlled, 

turbocharged, and with per-cylinder 

displacements greater than 0.5 liters. As 

discussed in more detail below, as well 

as in section II.B.5 (regarding the under 

25 hp category), these engine 

distinctions are important from a 

technology perspective and warrant a 

different set of standards for the 25–75 

hp category (as well as for the under 25 

hp category). 

b. Are the New Tier 4 Standards for 25– 

75 hp Engines Technologically Feasible? 

This section will discuss the technical 

feasibility of both the interim 2008 PM 

standard and the 2013 standards. For an 

explanation and discussion of the 

implementation dates, please refer to 

section II.A. 

i. 2008 PM Standards 54 

We are today finalizing the interim 

PM control program as proposed for 

engines in the power category from 25– 

75 hp. The new PM standard for 2008 

is 0.22 g/bhp-hr over the appropriate 

steady-state test cycle (the NRTC and 

NTE do not apply, for the reasons 

explained below).55 The standard is 

premised on the use of 500 ppm sulfur 

diesel fuel and the potential for 

improvements in engine-out emission 

control where possible or the 

application of a diesel oxidation catalyst 

(DOC). Some commenters raised 

concerns that this level of emission 

control from diesel engines may not be 

possible in 2008 without fuel cleaner 

than 500 ppm or without changes in the 

Tier 3 NMHC+NOX emission standards. 

Other commenters, including some 

engine manufacturers, supported this 

interim program. As explained in the 

following sections, we continue to 

believe that these standards are 

appropriate and feasible in the leadtime 

provided. 

Engines in the 25–50 hp category 

must meet Tier 2 NMHC+NOX and PM 

standards today. We have examined the 

model year 2004 engine certification 

data for engines in the 25–50 hp 

category. These data indicate that over 

35 percent of the engine families meet 

the 2008 0.22 g/bhp-hr PM standard and 

5.6 g/bhp-hr NMHC+NOX standard 

(unchanged from Tier 2 in 2008) today 

(even without 500 ppm sulfur diesel 

fuel). At the time of the proposal, we 

had analyzed model year 2002 data for 

this power range, which at that time 

indicated approximately 10 percent of 

the engine families complied with the 

2008 requirements. The most recent 

data for model year 2004 indicates 

substantial progress has already been 

made in just the past few year in 

lowering emissions from these engines. 

This is primarily due to the 

implementation of the Tier 2 standards 

in model year 2004. The model year 

54 As discussed in section II.B., manufacturers can 

choose, at their option, to pull-ahead the 2013 PM 

standard for the 50–75 hp engines to 2012, in which 

case they do not need to comply with the 

transitional 2008 PM standard. 

55 However, a manufacturer can choose to comply 

over the TRU cycle including the associated NTE 

provisions. Compliance with the NTE for engines 

selecting to certify on the TRU cycle is 

straightforward because by the very nature of the 

products, their operation is directly limited to a 

small range of operating modes over which 

compliance with the emission standard has already 

been shown. 
38992 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

2001 certification data also showed the 

2008 standard were achievable using a 

mix of engine technologies (IDI and DI, 

turbocharged and naturally aspirated) 

tested on a variety of certification test 

cycles.56 A detailed discussion of these 

data is contained in the RIA. 

At the time of the proposal, no 

certification data was available for 

engines in the 50–75 hp range, because 

those engines were not subject to a Tier 

1 standard and were not subject to Tier 

2 standards until model year 2004. We 

have now had an opportunity to analyze 

the model year 2004 certification data 

for engines in the 50–75 hp range. These 

data shows that more than 70 percent of 

the engine families in this power range 

are capable of meeting the 2008 PM 

standards today. However, most of these 

engines do not yet meet the 3.5 g/bhphr Tier 3 NMHC+NOX standard, which 

is required in 2008. We expect that to 

comply with the Tier 3 standards, these 

engines will use technologies such as 

EGR and electronically controlled fuel 

injection systems (and we included the 

costs of these technologies in assessing 

the costs of the Tier 3 standards). These 

technologies have been shown to reduce 

NOX emissions by 50 percent without 

increasing PM emissions. The 

certification data show that for the 70 

percent of the engine families which 

meet the 2008 Tier 4 PM standard (0.22 

g/bhp-hr), a NOX reduction of less than 

50 percent is needed for most of these 

engines to meet the 2008 Tier 4 

NMHC+NOX standard. A detailed 

discussion of these data is contained in 

the RIA. 

In addition to using known engine-out 

techniques, we also project that the 

2008 standards can be achieved with the 

use of DOCs. DOCs are passive flowthrough emission control devices which 

are typically coated with a precious 

metal or a base-metal washcoat. DOCs 

have been proven to be durable in use 

on both light-duty and heavy-duty 

diesel applications. In addition, DOCs 

have already been used to control 

carbon monoxide on some nonroad 

applications.57 Some commenters raised 

concerns that DOCs could actually 

increase PM emissions when used on 

500 ppm sulfur diesel fuel due to the 

potential for oxidation of the sulfur in 

the fuel to sulfate PM. While we agree 

56 The Tier 1 and Tier 2 standards for this power 

category must be demonstrated on one of a variety 

of different engine test cycles. The appropriate test 

cycle is selected by the engine manufacturer based 

on the intended in-use application of the engine. 

57 EPA Memorandum ‘‘Documentation of the 

Availability of Diesel Oxidation Catalysts on 

Current Production Nonroad Diesel Equipment,’’ 

William Charmley. Copy available in EPA Air 

Docket A–2001–28 Item II–B–15. 

with the commenters that sulfur 

reductions are important to control PM 

and in the long term that a 15 ppm fuel 

sulfur level will be the best solution, we 

disagree with the assertion that the 

amount of sulfate PM formed from a 

DOC will be such that compliance with 

the 0.22 g/bhp-hr standard will be 

infeasible. While commenters shared 

data showing increased PM emissions 

when DOCs are used, we have similarly 

found data (included in the RIA) that 

shows an overall reduction in 

emissions. To understand this 

discrepancy, it is important to realize 

that DOCs can be designed for operation 

on a range of fuel sulfur levels. The 

lower the fuel sulfur level, the more 

effective the PM oxidation function, but 

even at 500 ppm sulfur a properly 

designed DOC will realize a net 

reduction in PM emissions. DOCs have 

been successfully applied to diesel 

engines for on-highway applications for 

PM control on 500 ppm fuel since 1994 

through careful design of the DOC 

trading-off PM reduction potential and 

sulfur oxidation potential. The RIA 

contains additional analysis describing 

DOC function, and its expected 

effectiveness when applied to nonroad 

diesel engines. 

Other commenters argued that the 

application of DOC to diesel engines in 

this category would lead to an even 

greater emission reduction than 

estimated in our proposal, thus allowing 

the Agency to finalize a lower PM 

standard. While we agree that some 

engines will have lower emissions than 

required to meet the standard and that 

in the long term (once 15 ppm fuel is 

widely available) the PM emissions will 

be further reduced, we do not believe 

that an emission level lower than 0.22 

g/bhp-hr will be generally feasible in 

2008 due to the sulfur level of diesel 

fuel of 500 ppm sulfur and the potential 

for sulfate PM formation. 

In summary then, there are two likely 

means by which companies can comply 

with the interim 2008 PM standard. 

First, engine manufacturers can comply 

with this standard using known engineout techniques (e.g., optimizing 

combustion chamber designs, fuelinjection strategies). In fact, some 

fraction of engines already would 

comply with the emission standard. In 

addition, some engine manufacturers 

may choose to use diesel oxidation 

catalysts to meet this standard. Our cost 

analysis makes the conservative 

assumption (i.e., the higher cost 

assumption) that all manufacturers will 

use DOC catalysts to comply with these 

emission standards. 

Based on the existence of a number of 

engine families which already comply 

with the 0.22 g/bhp-hr PM standard 

(and the 2008 NMHC+NOX standard), 

and the availability of well known PM 

reduction technologies such as engineout improvements and diesel oxidation 

catalysts, we project that the 0.22 g/bhphr PM standards is technologically 

feasible by model year 2008. 

ii. 2013 Standards 

For engines in the 25–50 range, we are 

finalizing standards commencing in 

2013 of 3.5 g/bhp-hr for NMHC+NOX 

and 0.02 g/bhp-hr for PM. For the 50– 

75 hp engines, we are finalizing a 0.02 

g/bhp-hr PM standard which will be 

implemented in 2013, and for those 

manufacturers who choose to pullahead the standard one-year, 2012 

(manufacturers who choose to pullahead the 2013 standard for engines in 

the 50–75 range do not need to comply 

with the transitional 2008 PM standard). 

A more complete discussion of the 

options available to manufacturers and 

the nature of the transitional program 

can be found in section II.A. These 

standards are measured using the NRTC 

and steady-state tests. These engines 

also will be subject to the NTE starting 

with the 2013 model year. 

PM Standard. For engines in the 

horsepower category from 25–75 hp, we 

are finalizing a PM standard of 0.02 g/ 

bhp-hr based on the application of 

catalyzed diesel particulate filters to 

engines in this category. We received a 

wide range of comments on our 

proposal with some arguing that the 

emission standard could be met earlier 

than 2013 and others arguing that while 

technically possible to apply PM filters 

to engines in this category, that it was 

not economically or otherwise practical 

to do so. 

The RIA discusses in detail catalyzed 

diesel particulate filters, including 

explanations of how CDPFs reduce PM 

emissions, and how to apply CDPFs to 

nonroad engines. We have concluded, 

as explained above, that CDPFs can be 

used to achieve the 0.01 g/bhp-hr PM 

standard for 75–750 hp engines. As also 

discussed in section II.B.2.a above, PM 

filters will require active back-up 

regeneration systems for many nonroad 

applications above and below 75 hp 

because low temperature operation is an 

issue across all power categories. One 

commenter raised concerns regarding 

the low exhaust temperatures possibly 

experienced by small nonroad engines 

and argued that such low temperatures 

make PM filter regeneration impossible 

absent the use of active regeneration 

technologies. We agree with the 

commenter that active regeneration, as 

described previously, may be necessary 

and have included the cost for such 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38993 

systems in our cost estimates. See 

section II.B.1.a. A number of secondary 

technologies are likely required to 

enable proper regeneration, including 

possibly electronic fuel systems such as 

common rail systems which are capable 

of multiple post-injections which can be 

used to raise exhaust gas temperatures 

to aid in filter regeneration. 

Particulate filter technology, with the 

requisite trap regeneration technology, 

can also be applied to engines in the 25 

to 75 hp range. As explained earlier, the 

fundamentals of how a filter is able to 

reduce PM emissions are not a function 

of engine power, so that CDPF’s are just 

as effective at capturing soot emissions 

and oxidizing SOF on smaller engines 

as on larger engines. The PM filter 

regeneration systems described in 

section II.B.2 are also applicable to 

engines in this size range and are 

likewise feasible. There are specific trap 

regeneration technologies which we 

believe engine manufacturers in the 25– 

75 hp category may prefer over others. 

For example, some manufacturers may 

choose to apply an electronicallycontrolled secondary fuel injection 

system (i.e., a system which injects fuel 

into the exhaust upstream of a PM 

filter). Such a system has been 

commercially used successfully by at 

least one nonroad engine manufacturer, 

and other systems have been tested by 

technology companies.58 However, we 

recognize that the application of these 

technologies will be challenging and 

will require additional time to develop. 

We therefore disagree with commenters 

who say that the standard could be met 

sooner and have decided to finalize the 

implementation schedule as proposed. 

As we proposed, we are finalizing a 

slightly higher PM standard (0.02 g/bhphr rather than 0.01) for engines in this 

power category. As discussed in the 

preamble to the proposed rule and in 

some detail in the RIA, with the use of 

a CDPF, the PM emissions emitted by 

the filter are primarily derived from the 

fuel sulfur (68 FR 28389–28390, May 23, 

2003). The smaller power category 

engines tend to have higher fuel 

consumption per unit of work than 

larger engines. This occurs for a number 

of reasons. First, the lower power 

categories include a high fraction of IDI 

engines which by their nature consume 

approximately 15 percent more fuel 

than a DI engine. Second, as engine 

displacements get smaller, the engine’s 

combustion chamber surface-to-volume 

58 ‘‘The Optimized Deutz Service Diesel 

Particulate Filter System II,’’ H. Houben et. al., SAE 

Technical Paper 942264, 1994 and ‘‘Development of 

a Full-Flow Burner DPF System for Heavy Duty 

Diesel Engines,’’ P. Zelenka et. al., SAE Technical 

Paper 2002–01–2787, 2002. 

ratio increases. This leads to higher 

heat-transfer losses and therefore lower 

efficiency and higher fuel consumption. 

In addition, frictional losses are a higher 

percentage of total power for the smaller 

displacement engines which also results 

in higher fuel consumption. Because of 

the higher fuel consumption rate, we 

expect a higher particulate sulfate level, 

and therefore we have set a 0.02 g/bhphr standard for engines in this power 

category. We did not receive any 

comments on our proposal arguing that 

the technical basis for this higher PM 

level was inappropriate. 

The 0.02 g/bhp-hr standard applies to 

all of the test cycles applicable to 

engines in this power category (i.e., the 

NRTC including cold-start, the ISO C1, 

D2 and G2 cycles and the alternative 

TRU and RMC cycles, as appropriate). 

Our feasibility analysis summarized 

here and detailed in the RIA takes into 

consideration these different test cycles. 

The control technologies work in a 

similar manner and provide the same 

high level of emission control across 

these different operating regimes 

including the NTE. The most significant 

effect on emission performance is 

related to sulfate PM formation at high 

load, high temperature operating 

conditions. As the RIA details, this level 

of high sulfate formation rate is not high 

enough to preclude compliance with the 

PM emission standard with 15 ppm fuel 

sulfur on the regulated test cycles nor is 

it high enough to preclude compliance 

with the NTE provisions. At higher fuel 

sulfur levels however, compliance with 

the PM emission standard would not be 

feasible. 

The majority of negative comments on 

our proposal to set a PM standard based 

on the control possible from PM filter 

technologies focused on the economic 

and technical challenges to apply these 

technologies and the major engine 

technology enabler, electronic fuel 

systems, to smaller diesel engines. Some 

commenters acknowledged that the 

technologies were ‘‘technically feasible’’ 

but not economically feasible or 

practical for engines in this power 

category. While we acknowledge that 

the application of these technologies to 

diesel engines in this horsepower 

category will be challenging and have 

given consideration to this in setting the 

timing for the new standard, we believe 

that the technical path for compliance is 

clear and that the cost estimates we 

have made for these engines accurately 

represent this technical path. As 

discussed in the RIA, at the time of the 

proposal we projected no significant 

penetration of electronic fuel systems 

for engines in the 50–100 hp range prior 

to the Tier 3 standards (2008). Since the 

proposal, new information regarding 

model year 2004 engine certifications 

has become available. That data show 

18 percent of the engines in the 75–100 

hp category already use electronically 

controlled fuel systems. In model year 

2001, no engines in this category used 

electronic fuel systems. We believe this 

strong trend toward the introduction of 

more advanced electronic fuel system 

technology will continue in the future 

and, importantly for engines in the 25– 

75 hp category, will extend to ever 

smaller engine categories due to the user 

benefits provided by the technology and 

the falling cost for such systems. 

However, acknowledging the substantial 

time between now and 2012, and the 

potential for technologies to mature 

faster or slower than we are estimating 

here, we have decided to conduct a 

technology review of these standards as 

described in section II.A above. This 

review will provide EPA with another 

opportunity to confirm that the 

technical path laid out here is indeed 

progressing in a manner consistent with 

our expectations. 

NMHC+NOX Standard. As we 

proposed, we are finalizing a 3.5 g/bhphr NMHC+NOX standard for engines in 

the 25–50 hp range for 2013. We 

received limited comments arguing that 

the NMHC+NOX standard should be less 

stringent. Like the PM standard, some 

commenters argued that the NOX 

standard would be costly and 

complicated, although not necessarily 

infeasible to apply. Other commenters 

argued that the NOX standard for 

engines in this category like the new 

standard for larger engines, should be 

based upon the application of advanced 

NOX catalyst-based technologies. As 

described previously in section II.A, we 

do not believe that the catalyst-based 

NOX technologies have matured to a 

state were we can accurately define a 

feasible technical path for compliance 

for engines in this power category. We 

intend to revisit this question in our 

technology review and if we find that a 

viable technical path can be described 

we will consider the appropriateness of 

a more stringent catalyst-based 

standard. 

The new standard aligns the 

NMHC+NOX standard for engines in 

this power range with the Tier 3 

standard for engines in the 50–75 hp 

range which are implemented in 2008. 

EPA’s recent Staff Technical paper 

which reviewed the technological 

feasibility of the Tier 3 standards 

contains a detailed discussion of a 

number of technologies which are 

capable of achieving a 3.5 g/bhp-hr 

standard. These include cooled EGR, 

uncooled EGR, as well as advanced in-
38994 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

cylinder technologies relying on 

electronic fuel systems and 

turbocharging.59 These technologies are 

capable of reducing NOX emissions by 

as much as 50 percent. Given the Tier 

2 NMHC+NOX standard of 5.6 g/bhp-hr, 

a 50 percent reduction would allow a 

Tier 2 engine to comply with the 3.5 g/ 

bhp-hr NMHC+NOX standard set in this 

action. Therefore, we are projecting that 

3.5 g/bhp-hr NOX+NMHC standard is 

feasible with the addition of cooled EGR 

(the basis for our cost analysis) or other 

equally effective in-cylinder NOX 

control technology as described in the 

RIA and our recent Staff Technical 

Paper. In addition, because this 

NMHC+NOX standard is concurrent 

with the 0.02 g/bhp-hr PM standards 

which we project will be achievable 

with the use of particulate filters, engine 

designers will have significant 

additional flexibility in reducing NOX 

because the PM filter will lessen the 

traditional concerns with the engine-out 

NOX vs. PM trade-off. 

Our recent highway 2004 standard 

review rulemaking (see 65 FR 59896, 

October 2000) demonstrated that a 

diesel engine with advanced electronic 

fuel injection technology as well as NOX 

control technology such as cooled EGR 

is capable of complying with an NTE 

standard set at 1.25 times the laboratorybased FTP standard. We project that the 

same technology (electronic fuel 

systems and cooled EGR) are also 

capable for engine in the 25–75 hp range 

of complying with the NTE standard of 

4.4 g/bhp-hr NMHC+NOX (1.25 × 3.5) in 

2013. This is based on the broad NOX 

reduction capability of cooled EGR 

technology, which is capable of 

reducing NOX emissions across the 

engine operating map (including the 

NTE region) by at least 30 percent even 

under high load conditions.60 

Based on the information available to 

EPA and presented here, and giving 

appropriate consideration to the lead 

time necessary to apply the technology 

as well, we have concluded the 0.02 g/ 

bhp-hr PM standard for engines in the 

25–75 hp category and the 3.5 g/bhp-hr 

NMHC+NOX standards for the 25–50 hp 

engines are achievable. 

59 See section 2.2 through 2.3 in ‘‘Nonroad Diesel 

Emission Standards—Staff Technical Paper,’’ EPA 

Publication EPA420–R–01–052, October 2001. Copy 

available in EPA Air Docket A–2001–28. 

60 See section 8 of ‘‘Control of Emissions of Air 

Pollution from 2004 and Later Model Year HeavyDuty Highway Engines and Vehicles: Response to 

Comments,’’ EPA document EPA420–R–00–011, 

July 2000, and chapter 3 of ‘‘Regulatory Impact 

Analysis: Control of Emissions of Air Pollution 

from Highway Heavy-duty Engines,’’ EPA 

document EPA420–R–00–010, July 2000. Copies of 

both documents available in EPA docket A–2001– 

28. 

5. Are the Standards for Engines Under 

25 hp Feasible? 

As we explained at proposal and as 

discussed in section II.A, the new PM 

standard for engines less than 25 hp is 

0.30 g/bhp-hr beginning in 2008. The 

certification test cycle for this standard 

is the ISO C1 cycle (or other appropriate 

steady-state test as defined by the 

engine’s intended use) from 2008 

through 2012. Beginning in 2013, the 

NRTC (with cold-start) and the NTE will 

also apply to engines in this category. 

As discussed below, we are not setting 

a new standard more stringent than the 

existing Tier 2 NMHC+NOX standard for 

this power category at this time. This 

section describes what makes the less 

than 25 hp category different and why 

the standards are technologically 

feasible. 

a. What Makes the Under 25 hp 

Category Unique? 

As we explained at proposal and in 

the RIA, nonroad engines less than 25 

hp are the least sophisticated nonroad 

diesel engines from a technological 

perspective. All of the engines currently 

sold in this power category lack 

electronic fuel systems and 

turbochargers. Nearly 20 percent of the 

products have two-cylinders or less, and 

14 percent of the engines sold in this 

category are single-cylinder products, a 

number of these have no batteries and 

are crank-start machines, much like 

today’s simple walk behind lawnmower 

engines. In addition, given what we 

know today and taking into account the 

Tier 2 standards which have not yet 

been implemented, we are not 

projecting any significant penetration of 

advanced engine technology, such as 

electronically controlled fuel systems, 

into this category in the next 5 to 10 

years. 

b. What Data Indicate That the 

Standards Are Feasible? 

We project the Tier 4 PM standard can 

be met by 2008 based on: The existence 

of a large number of engine families 

which meet the new standards today; 

the use of engine-out reduction 

techniques; and the use of diesel 

oxidation catalysts. 

Engines in the less than 25 hp 

category must meet Tier 1 NMHC+NOX 

and PM standards today. We have 

examined the 2004 model year engine 

certification data for nonroad diesel 

engines less than 25 hp. These data 

indicate that a number of engine 

families meet the new Tier 4 PM 

standard (and the 2008 NMHC+NOX 

standard, unchanged from Tier 2) today. 

The data show that 31 percent of the 

engine families are at or below the PM 

standard today, while meeting the 2008 

NMHC+NOX standard. At the time of 

the proposal, we examined the model 

year 2002 certification, which indicated 

approximately 30 percent of the engine 

families were at or below the 2008 

emission standards. This certification 

data includes both IDI and DI engines, 

as well as a range of certification test 

cycles.61 Many of the engine families are 

certified well below the Tier 4 standard 

while meeting the 2008 NMHC+NOX 

level. Specifically, for the model year 

2002 data, 15 percent of the engine 

families are cleaner than the new Tier 

4 PM standard by more than 20 percent. 

The public certification data indicate 

that these engines do not use 

turbocharging, electronic fuel systems, 

exhaust gas recirculation, or 

aftertreatment technologies. We saw 

little change between the model year 

2002 and 2004 data for this power 

category primarily because both model 

years are subject to the Tier 1 standards, 

and many engine families are simply 

carried over from the previous model 

year. Tier 2 standards for these engines 

will not be implemented until model 

year 2005. A detailed discussion of 

these data is contained in the RIA. 

In summary then, there are two likely 

means by which companies can comply 

with the 2008 PM standard for engines 

under 25 hp. First, engine 

manufacturers can comply with this 

standard using known engine-out 

techniques (e.g., optimizing combustion 

chamber designs, fuel-injection 

strategies). In fact, some fraction of 

engines already would comply with the 

emission standard. In addition, some 

engine manufacturers may choose to use 

diesel oxidation catalysts to meet this 

standard. Our cost analysis makes the 

conservative assumption (i.e., the higher 

cost assumption) that all manufacturers 

will use DOCs to comply with these 

emission standards. 

As discussed in section II.A, we are 

finalizing supplemental test procedures 

and standards (nonroad transient test 

cycle and not-to-exceed requirements) 

for engines in the under 25 hp category 

beginning in 2013. The supplemental 

test procedures and standards will 

apply not only to PM, but also to 

NMHC+NOX. The engine technologies 

necessary to comply with the 

supplemental test procedures and 

standards are the same as the 

technology necessary to comply with 

the 2008 standard, and we have given 

61 The Tier 1 and Tier 2 standards for this power 

category must be demonstrated on one of a variety 

of different engine test cycles. The appropriate test 

cycle is selected by the engine manufacturer based 

on the intended in-use application(s) of the engine. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38995 

consideration to these test conditions in 

setting this standard. The range of 

operating conditions covered by the 

various test cycles and the mechanism 

for emission control over those ranges of 

operation are substantially similar 

allowing us to conclude that emission 

control will be substantially uniform 

across these test procedures. However, 

we are delaying the implementation of 

the supplemental test procedures and 

standards until 2013, as proposed, in 

order to implement these supplemental 

requirements on the larger powered 

nonroad engines before the smallest 

power category. (There were no adverse 

comments on this aspect of the 

proposed rule.) This will also provide 

engine manufacturers with additional 

time to install any emission testing 

equipment upgrades they may need in 

order to implement the new nonroad 

transient test cycle. 

Based on the existence of a number of 

engine families which already comply 

with the new Tier 4 PM standard (and 

the 2008 NMHC+NOX standard), and 

the availability of PM reduction 

technologies such as improved 

mechanical fuel systems, combustion 

chamber improvements, and in 

particular diesel oxidation catalysts, we 

project that the 0.30 g/bhp-hr PM 

standards is technologically feasible by 

model year 2008. 

6. Meeting the Crankcase Emissions 

Requirements 

The most common way to eliminate 

crankcase emissions has been to vent 

the blow-by gases into the engine air 

intake system, so that the gases can be 

recombusted. Prior to the HD2007 

rulemaking, we have required that 

crankcase emissions be controlled only 

on naturally aspirated diesel engines. 

We had made an exception for 

turbocharged diesel engines (both 

highway and nonroad) because of 

concerns in the past about fouling that 

could occur by routing the diesel 

particulates (including engine oil) into 

the turbocharger and aftercooler. 

However, this is an environmentally 

significant exception since most 

nonroad equipment over 75 hp use 

turbocharged engines, and a single 

engine can emit over 100 pounds of 

NOX, NMHC, and PM from the 

crankcase over its lifetime. 

Given the available means to control 

crankcase emissions, we eliminated this 

exception for highway engines in 2007 

and similarly in today’s action are 

eliminating the exception for nonroad 

diesel engines as well. A number of 

commenters supported this provision 

noting that the necessary technologies 

are already in application in Europe and 

will be required for heavy-duty diesel 

trucks in the United States beginning in 

2007. 

We anticipate that the diesel engine 

manufacturers will be able to control 

crankcase emissions through the use of 

closed crankcase filtration systems or by 

routing unfiltered blow-by gases directly 

into the exhaust system upstream of the 

emission control equipment. However, 

the provisions have been written such 

that if adequate control can be had 

without ‘‘closing’’ the crankcase then 

the crankcase can remain ‘‘open.’’ 

Compliance would be ensured by 

adding the emissions from the crankcase 

ventilation system to the emissions from 

the engine control system downstream 

of any emission control equipment. We 

have limited this provision for 

controlling emissions from open 

crankcases to turbocharged engines, 

which is the same as for heavy-duty 

highway diesel engines. 

Some commenters in essence argued 

that the Agency was obligated to show 

that all potential compliance paths were 

feasible and absent that showing that 

the Agency should reconsider this 

provision. Our feasibility analysis is 

based on the use of closed crankcase 

technologies designed to filter crankcase 

gases sending the clean gas to the engine 

intake for combustion and returning the 

oil filtered from the gases to the engine 

crankcase. These systems are proven in 

use and the use of this technology to 

eliminate crankcase emissions is 

acceptable to demonstrate compliance. 

The other options, the option to vent 

crankcase emissions into the exhaust or 

to continue to vent crankcase emissions 

to the atmosphere provided the total 

emissions including tailpipe and 

crankcase emissions do not exceed the 

standards are provided as alternate 

solutions that are clearly effective to 

control emissions (i.e., if the emissions 

are measured and are below the 

standard they are adequately 

controlled). The commenter suggests 

however, that they may not be able to 

control the emissions to the required 

level using these alternate approaches. 

In this case, a manufacturer would need 

to use the primary approach identified 

by EPA, closing the crankcase and 

routing the filtered gases to the engine’s 

intake (this is the approach we used in 

the cost analysis summarized in section 

VI). We have allowed the alternative 

approaches at the recommendation of 

some in industry, because if they prove 

to be effective we accept that resulting 

total emissions will be acceptably low. 

C. Why Do We Need 15 ppm Sulfur 

Diesel Fuel? 

The new Tier 4 emission standards for 

most categories of nonroad diesel 

engines are predicated on the 

application of advanced diesel emission 

control technologies that are being 

developed for on-highway diesel 

engines to meet the HD2007 emission 

standards, namely catalyzed diesel 

particulate filters and NOX adsorber 

catalysts. Sulfur in diesel fuel 

significantly impacts the durability, 

efficiency and cost of applying these 

technologies. Therefore, we required 

that on-highway diesel fuel produced 

for use in 2007 or newer on-highway 

diesel engines have sulfur content no 

higher than 15 ppm. Based on the same 

concerns outlined in the 2007 

rulemaking, discussed in the proposal at 

68 FR 28395–28400, set out in the RIA, 

and briefly summarized below, we 

today are finalizing a requirement that 

diesel fuel for nonroad engines be 

reduced to no higher than 15 ppm 

beginning in 2010. There was consensus 

among commenters that such standards 

were necessary if the proposed 

standards based on advanced diesel 

emission control technologies were to 

be achievable. 

Sulfur in diesel fuel acts to poison the 

oxidation function of platinum-based 

catalysts including DOCs and CDPFs 

reducing the oxidation efficiency 

substantially, especially at lower 

temperatures. This poisoning limits the 

effectiveness of DOCs and CDPFs to 

oxidize CO and HC emissions. Of even 

greater concern is the reduction in NO 

oxidation efficiency of the CDPF due to 

sulfur poisoning. NO oxidation to NO2 

is a fundamental mechanism for PM 

filter regeneration necessary to ensure 

robust operation of the CDPF (i.e., to 

prevent filter plugging). Sulfur 

poisoning from sulfur in diesel fuel at 

levels higher than 15 ppm has been 

shown to increase the likelihood of PM 

filter failure due to a depressed NO to 

NO2 oxidation efficiency of the CDPF. 

The RIA documents substantial field 

experience in Europe regarding this 

phenomenon. 

Sulfur in diesel fuel can itself be 

oxidized to form sulfate PM emitted into 

the environment. CDPFs in particular 

are designed for robust regeneration and 

are highly effective at oxidizing sulfur to 

sulfate PM (approaching 100 percent 

conversion under some circumstances). 

The sulfate PM emissions from a CDPF 

when operated on 350 ppm fuel can be 

so high as to actually increase the PM 

emission rate above the baseline level 

for an engine without a PM filter. In 

spite of more than ten years of research, 
38996 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

no effective means has been found to 

provide the NO to NO2 oxidation 

efficiency needed to ensure robust filter 

regeneration without similarly 

increasing efficiency to oxidize sulfur to 

sulfate PM. Conversely, technologies 

developed to suppress sulfate PM 

formation (e.g., the addition of 

vanadium to DOCs designed to operate 

on 500 ppm sulfur fuel) also suppress 

NO to NO2 formation. Therefore, it is 

not possible to apply the robust CDPF 

technology to achieve the PM standards 

without first having lower diesel fuel 

sulfur levels. The RIA documents 

substantial test data showing the impact 

of sulfur in diesel fuel on total PM 

emissions due to an increase in sulfate 

PM emissions. 

Sulfur from diesel fuel likewise 

poisons the storage function of the NOX 

adsorber catalyst. Sulfur in the exhaust 

in the form of SOX is stored on the 

catalyst in the same way as the NOX 

emissions are stored. Unfortunately, due 

to the chemical properties of the 

materials, the sulfur is stored 

preferentially to the NOX and will 

actually displace the stored NOX 

emissions. The stored sulfur is not 

easily removed from the catalyst. A 

sulfur removal step, called a 

desulfation, can be accomplished by 

raising exhaust temperatures to a very 

high level while simultaneously 

increasing the reductant content of the 

exhaust above the stoichiometric level 

(i.e., more fuel than oxygen in the 

exhaust). This process can be effective 

to remove sulfur from the catalyst but at 

the expense of damaging the catalyst 

slightly. Over the lifetime of a diesel 

engine the cumulative damage from 

repeated desulfation events, as would be 

required if operation on higher than 15 

ppm sulfur fuels were attempted, would 

lead to excessive damage and loss in 

NOX control. The RIA contains an 

extensive description of this phenomena 

including the tradeoff between higher 

fuel sulfur levels and more frequent 

desulfation events. 

The damage that sulfur inflicts on 

both the CDPF and NOX adsorber 

technologies not only reduces their 

effectiveness but also impacts the fuel 

economy of their application. Reduced 

soot regeneration potential due to sulfur 

poisoning would lead to the need for 

more frequent active CDPF regeneration. 

As each active soot regeneration event 

consumes fuel, more frequent 

regeneration events with higher fuel 

sulfur levels leads to an increase in fuel 

consumption. Similarly, higher fuel 

sulfur levels would necessitate more 

frequent NOX adsorber desulfation 

events and thus higher fuel 

consumption. An estimate of the impact 

of higher fuel sulfur levels on fuel 

economy due to more frequent 

desulfation events can be found in the 

RIA. 

For all of the reasons documented in 

the RIA and summarized here, we 

remain convinced that a cap of 15 ppm 

fuel sulfur is necessary for both onhighway and nonroad diesel engines in 

order to apply the advanced emission 

control technologies necessary to meet 

the emission standards we are finalizing 

today. 

III. Requirements for Engine and 

Equipment Manufacturers 

This section describes the regulatory 

changes being made for the engine and 

equipment compliance program. A 

number of specific items are discussed 

in this section, including test 

procedures, certification fuels, and 

credit program provisions. These 

provisions are important in that they 

help us ensure the engines and 

equipment will meet the new 

requirements throughout their entire 

useful life, thus achieving the expected 

emission and public health benefits. 

One of the most obvious changes from 

the Tier 2/Tier 3 program is that the 

regulations for Tier 4 engines have been 

written in a plain language format. They 

are structured to contain the provisions 

that are specific to nonroad compression 

ignition (CI) engines in a new part 1039, 

and to apply the general provisions of 

existing parts 1065 and 1068. The plain 

language regulations, however, are not 

intended to significantly change the 

compliance program, except as 

specifically noted in today’s notice and 

supporting documents. These plain 

language regulations will only apply for 

Tier 4 engines. The changes from the 

existing nonroad program are described 

below along with other notable aspects 

of the compliance program. 

As described below, we received 

comments from a broad range of 

commenters for some of these issues. 

For other issues, we received only 

manufacturer comments or no 

comments at all. See Chapter 9 of the 

Summary and Analysis of Comments for 

more information about the comments 

received and our responses to them. 

A. Averaging, Banking, and Trading 

1. Why Are We Adopting an ABT 

Program for Tier 4 Nonroad Diesel 

Engines? 

EPA has included averaging, banking, 

and trading (ABT) programs in almost 

all of its recent mobile source emission 

control programs. Our existing 

regulations for nonroad diesel engines 

include an ABT program (40 CFR 89.201 

through 89.212). With today’s action we 

are retaining the basic structure of the 

existing nonroad diesel ABT program, 

though we are adopting a number of 

changes to accommodate 

implementation of the newly adopted 

Tier 4 emission standards. The ABT 

program is intended to enhance the 

ability of engine manufacturers to meet 

the stringent standards adopted today. 

The program is also structured to limit 

production of very high-emitting 

engines and to avoid unnecessary delay 

of the transition to the new exhaust 

emission control technologies. 

We view the ABT program as an 

important element in setting emission 

standards that are appropriate under 

CAA section 213(a) with regard to 

technological feasibility, lead time, and 

cost, given the wide breadth and variety 

of engines covered by the standards. As 

we noted at proposal, if there are engine 

families that will be particularly costly 

or have a particularly hard time coming 

into compliance with the standard, this 

flexibility allows the manufacturer to 

adjust the compliance schedule 

accordingly, without special delays or 

exceptions having to be written into the 

rule. Emission-credit programs also 

create an incentive for the early 

introduction of new technology (for 

example, to generate credits in early 

years to create compliance flexibility for 

later engines), which allows certain 

engine families to act as trailblazers for 

new technology. This can help provide 

valuable information to manufacturers 

on the technology before they apply the 

technology throughout their product 

line. This early introduction of clean 

technology improves the feasibility of 

achieving the standards and can provide 

valuable information for use in other 

regulatory programs that may benefit 

from similar technologies. Early 

introduction of such engines also 

secures earlier emission benefits. 

In an effort to make information on 

the ABT program more available to the 

public, we intend to issue an annual 

report summarizing use of the ABT 

program by engine manufacturers. The 

information contained in the reports 

will be based on the information 

submitted to us by engine 

manufacturers in their annual reports, 

and summarized in a way that protects 

the confidentiality of individual engine 

manufacturers. We believe this 

information will also be helpful to 

engine manufacturers by giving them a 

better indication of the availability of 

credits. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38997 

2. What Are the Provisions of the ABT 

Program? 

The following section describes the 

ABT provisions being adopted with 

today’s action. Areas in which we have 

made changes to the proposed ABT 

program are highlighted. A complete 

summary of comments received on the 

proposed ABT program and our 

response to those comments are 

contained in the Summary and Analysis 

of Comments document for this rule. 

The ABT program has three main 

components. Averaging means the 

exchange of emission credits between 

engine families within a given engine 

manufacturer’s product line. Engine 

manufacturers divide their product line 

into ‘‘engine families’’ that are 

comprised of engines expected to have 

similar emission characteristics 

throughout their useful life. Averaging 

allows a manufacturer to certify one or 

more engine families at levels above the 

applicable emission standard, but below 

a set upper limit. However, the 

increased emissions must be offset by 

one or more engine families within that 

manufacturer’s product line that are 

certified below the same emission 

standard, such that the average 

emissions from all the manufacturer’s 

engine families, weighted by engine 

power, regulatory useful life, and 

production volume, are at or below the 

level of the emission standard. (The 

inclusion of engine power, useful life, 

and production volume in the averaging 

calculations is designed to reflect 

differences in the in-use emissions from 

the engines.) 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 that is established 

above the standard may not exceed an 

upper limit specified in the ABT 

regulations. Once an engine family is 

certified to an FEL, that FEL becomes 

the enforceable emissions limit for all 

the engines in that family for purposes 

of compliance testing. Averaging is 

allowed only between engine families in 

the same averaging set, as defined in the 

regulations. 

Banking means the retention of 

emission credits by the engine 

manufacturer for use in future model 

year averaging or trading. Trading 

means the exchange of emission credits 

between nonroad diesel engine 

manufacturers which can then be used 

for averaging purposes, banked for 

future use, or traded to another engine 

manufacturer. 

The existing ABT program for 

nonroad diesel engines covers 

NMHC+NOX emissions as well as PM 

emissions. With today’s action and as 

proposed, we are making the ABT 

program available for the Tier 4 NOX 

standards (and NMHC+NOX standards, 

where applicable) and the Tier 4 PM 

standards. As proposed, ABT will not be 

available for the Tier 4 NMHC standards 

for engines above 75 horsepower. 

Engine manufacturers commented 

that ABT will most likely be necessary 

for the Tier 4 CO standards, given the 

reductions in PM and NOX emissions. In 

the Tier 4 proposal, we proposed minor 

changes in CO standards for some 

engines solely for the purpose of 

helping to consolidate power categories 

and improving administrative 

efficiency. However, as noted earlier in 

section II.A.6, we have withdrawn this 

aspect of the proposal. We do note, 

however, that we are applying new 

certification tests to all pollutants 

covered by the rule, the result being that 

Tier 4 engines will have to certify to CO 

standards measured by the transient test 

(including a cold start component), and 

the NTE. However, as shown in RIA 

chapter 4.1.1.2 (see e.g., note F), we 

believe that application of Tier 4 

technologies will lead to a reduction in 

CO emissions over the Tier 3 baseline. 

We thus believe the CO standards will 

be readily achievable under the 

transient test and NTE. Moreover, we 

believe that there will not be any 

associated costs: The CO standards can 

be met without any further 

technological improvements (i.e., 

improvements other than those already 

necessary to meet the Tier 4 standards) 

and these tests will already be used for 

certification. Since CO standards 

measured by the new certification tests 

are achievable without cost, there is no 

basis for allowing ABT because no 

additional lead time is needed. 

As noted earlier, the existing ABT 

program for nonroad diesel engines 

includes FEL caps—limits on how high 

the emissions from credit-using engine 

families can be. No engine family may 

be certified above these FEL caps. These 

limits provide manufacturers with 

compliance flexibility while protecting 

against the introduction of 

unnecessarily high-emitting engines. In 

the past, we have generally set the FEL 

caps at the emission levels allowed by 

the previous standard, unless there was 

some specific reason to do otherwise. 

With today’s action, we are taking a 

different approach because the level of 

the standards being adopted for most 

engines are significantly lower than the 

current level of the standards. The 

transfer to new technology is feasible 

and appropriate. Thus, as proposed, to 

ensure that the ABT provisions are not 

used to continue unnecessarily to 

produce old-technology high-emitting 

engines under the new program, the FEL 

caps are not, in general, set at the 

previous standards. Exceptions have 

been made for the NMHC+NOX standard 

for engines between 25 and 50 

horsepower effective in model year 2013 

and the NOX standards applicable to 

engines above 750 horsepower in 2011, 

where we are using the estimated NOXonly equivalent for the previously 

applicable NMHC+NOX standard for the 

FEL cap since the gap between the 

previous and newly adopted standards 

is approximately 40 percent (rather than 

90 percent for engines between 75 and 

750 horsepower), and because the 

technology basis for these standards can 

be a form of engine-out control, like the 

previous tier standards. This approach 

of setting FEL caps at lower levels than 

the previously applicable standards is 

consistent with the level of the FEL 

limits set in the 2007 on-highway 

heavy-duty diesel engine program. 

STAPPA/ALAPCO supported the 

proposed FEL caps. The Engine 

Manufacturers Association (EMA) 

commented that EPA should eliminate 

the FEL caps altogether. They believe 

FEL caps are unnecessary because the 

zero-sum requirement of ABT will 

ensure that there are no adverse 

emission impacts. Short of eliminating 

the FEL caps, they commented that EPA 

should set FEL caps at the level of the 

previous standards, not the more 

stringent levels proposed. With today’s 

action, EPA is adopting the FEL caps as 

proposed, with some exceptions for 

engines above 750 horsepower (where 

we are adopting different standards than 

originally proposed) and for phase-in 

engines between 75 and 750 horsepower 

(where we have adopted an option for 

manufacturers to certify to alternative 

NOX standards during the phase-in 

period). We continue to believe that it 

is important to ensure that technology 

turns over in a timely manner and that 

manufacturers do not continue 

producing large numbers of highemitting, old technology engines once 

the Tier 4 standards become fully 

effective. (As noted below, however, we 

are adopting provisions that allow 

manufacturers to produce a limited 

number of 75 to 750 horsepower engines 

for a limited period that are certified 

with FELs as high as the previous tier 

of standards.) For the Tier 4 standards, 

where the standards are being reduced 

by an order of magnitude, we believe 

this goal to be particularly important, 

and in keeping with the technology-
38998 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

forcing provisions of section 213(a). It 

simply would not be appropriate to 

have long-term FEL caps that allowed 

engines to indefinitely have emissions 

as high as ten times the level of the 

standard. 

For engines between 75 and 750 

horsepower certified using the phase-in/ 

phase-out approach, there will be two 

separate sets of engines with different 

FEL caps. For engines certified to the 

existing (Tier 3) NMHC+NOX standards 

during the NOX phase-in (referred to 

generally as ‘‘phase-out’’ engines), the 

FEL cap for these pollutants will (almost 

necessarily) be the existing FEL caps 

adopted in the October 1998 Tier 3 rule. 

For engines certified to the newly 

adopted Tier 4 NOX standard during the 

phase-in (referred to generally as 

‘‘phase-in’’ engines), we have revised 

the proposed FEL cap to be 0.60 g/bhphr, consistent with the proposed longterm Tier 4 NOX FEL cap. As described 

in section II.A.2.c above, we have used 

the creation of alternative NOX 

standards for engines between 75 and 

750 horsepower to restate the phase-in/ 

phase-out concept as a path truly 

focused on achieving high-efficiency 

NOX aftertreatment during the phase-in 

years. Setting the NOX FEL cap at 0.60 

g/bhp-hr for phase-in engines will 

ensure this happens if a manufacturer 

chooses to certify to the phase-in 

provisions. In contrast, the higher FEL 

caps which we proposed (see 68 FR 

28467–28468) would not have achieved 

this objective. 

Beginning in model year 2014 when 

the Tier 4 NOX standards for engines 

between 75 and 750 horsepower take 

full effect, we are adopting a NOX FEL 

cap of 0.60 g/bhp-hr for all engines. We 

reiterate that given the fact that the Tier 

4 NOX standard is approximately a 90 

percent reduction from the existing 

standards for engines between 75 and 

750 horsepower, we do not believe the 

previous standard is appropriate as the 

FEL cap for engines having to comply 

with the Tier 4 NOX standard of 0.30 g/ 

bhp-hr. We believe that the NOX FEL 

caps will ensure that manufacturers 

adopt NOX aftertreatment technology 

across all of their engine designs. 

For the interim PM standards for 

engines between 25 and 75 horsepower 

effective in model year 2008 and for the 

Tier 4 PM standards for engines below 

25 horsepower, we are adopting the 

previously applicable Tier 2 PM 

standards for the FEL caps (which do 

vary within the 25 to 75 horsepower 

category) because the gap between the 

previous standards and the newly 

adopted standards is approximately 50 

percent (rather than in excess of 90 

percent for engines between 75 and 750 

horsepower), and the technology basis 

for the 2008 PM standards can be a form 

of engine-out control, like the previous 

tier standard. For the Tier 4 PM 

standard effective in model year 2013 

for engines between 25 and 75 

horsepower, we are adopting a PM FEL 

cap of 0.04 g/bhp-hr, and for the Tier 4 

PM standard effective in model years 

2011 and 2012 for engines between 75 

and 750 horsepower, we are adopting a 

PM FEL cap of 0.03 g/bhp-hr. As with 

the Tier 4 NOX standards for these 

engines, given the fact that these Tier 4 

aftertreatment-based PM standards for 

engines between 25 and 750 horsepower 

are over 90 per cent more stringent than 

the previous standards, we do not 

believe the previous standards are 

appropriate as FEL caps once the Tier 4 

standards take effect. We believe that 

the newly adopted PM FEL caps will 

ensure that manufacturers adopt PM 

aftertreatment technology across all of 

their engine designs (except for a 

limited number of engines), yet will still 

provide substantial flexibility in 

meeting the standards. 

The final Tier 4 standards for engines 

above 750 horsepower have been 

revised from the proposal. We similarly 

revised a number of the proposed ABT 

provisions for engines above 750 

horsepower. Beginning in 2011, all 

engines above 750 horsepower will be 

required to meet a NOX standard of 2.6 

g/bhp-hr, except for those above 1200 

horsepower used in generator sets 

which will be required to meet a NOX 

standard of 0.50 g/bhp-hr. The NOX FEL 

cap for the 2011 standards will be 4.6 

g/bhp-hr, which is an estimate of the 

NOX emissions level that is expected 

under the combined NMHC+NOX 

standards that apply with the previously 

applicable tier for engines above 750 

horsepower. Beginning in 2011, all 

engines above 750 horsepower will have 

to meet a PM standard of 0.075 g/bhphr. The PM FEL cap for the 2011 PM 

standard will be the previouslyapplicable Tier 2 standard of 0.15 g/ 

bhp-hr. As noted above, because the 

2011 NOX and PM standards are 

approximately 50 percent lower than 

the previous standard (rather than in 

excess of 90 percent for engines between 

75 and 750 horsepower), and for most 

engines are based on performance of the 

same type of technology (engine-out), 

we are adopting the previously 

applicable Tier 2 standards for the FEL 

caps. 

Beginning in model year 2015, the 

0.50 g/bhp-hr NOX standard will apply 

to all engines above 750 horsepower 

used in generator sets. Beginning in 

model year 2015, the PM standard drops 

to 0.02 g/bhp-hr for engines greater than 

750 horsepower used in generator sets 

and 0.03 g/bhp-hr for engines greater 

than 750 horsepower used in other 

machines. Consistent with the Tier 4 

FEL caps for lower horsepower 

categories where the new standards are 

significantly lower than the previously 

applicable standards and reflect 

performance of aftertreatment 

technology, we are adopting a NOX FEL 

cap of 0.80 g/bhp-hr for engines used in 

generator sets and PM FEL caps of 0.04 

g/bhp-hr for engines used in generator 

sets and 0.05 g/bhp-hr for engines used 

in other machines (i.e., mobile 

machines). We believe that the FEL caps 

for engines above 750 horsepower will 

ensure that manufacturers adopt PM 

aftertreament technology across all of 

their engine designs and NOX 

aftertreatment for generator sets once 

the 2015 standards are adopted, while 

allowing for some meaningful use of 

averaging beginning in 2015. 

Table III.A–1 contains the FEL caps 

and the effective model year for the FEL 

caps (along with the associated 

standards adopted for Tier 4). It should 

be noted that for Tier 4, where we are 

adopting a new transient test for most 

engines, as well as retaining the current 

steady-state test, the FEL established by 

the engine manufacturer will be used as 

the enforceable limit for the purpose of 

compliance testing under both test 

cycles. In addition, under the NTE 

requirements, the FEL times the 

appropriate multiplier will be used as 

the enforceable limit for the purpose of 

such compliance testing. This is 

consistent with how FELs are used for 

compliance purposes in the 2007 onhighway heavy-duty diesel engine 

program. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 38999 

TABLEIII.A–1.—FEL CAPSFORTHETIER4 STANDARDSINTHEABT PROGRAM(G/BHP-HR) 

Power category Effective model year NOX stand-

ard NOX FEL cap PM standard 

PM 

FEL 

cap 

hp <25 (kW <19).......................................................2008+..............................

a

5.6 afor <11hp................

7.1

a

for >11hp 

c

0.300.60 

25 ≤ hp < 50 (19 ≤ kW <37).....................................2008–2012......................

a

5.6 a.................................0.220.45 

25 ≤ hp < 50 (19 ≤ kW <37).....................................2013+..............................

b3.5 b

.................................0.02

f 0.04 

50 ≤ hp < 75 (37 ≤ kW <56).....................................2008–2012

d

....................

a

3.5 a.................................0.220.30 

50 ≤ hp < 75 (37 ≤ kW <56).....................................2013+

e

............................

a

3.5 a.................................0.02

f

0.04 

75 ≤ hp < 175 (56 ≤ kW <130).................................2012+..............................0.300.60

fgh ............................

0.01

f

0.03

175 ≤ hp ≤ 750 (130 ≤ kW ≤ 560)............................2011+..............................0.300.60

fgh ............................

0.01

f

0.03 

hp > 750 (kW >560).................................................2011–2014......................2.64.6...................................0.0750.15 i

0.50 

Generator Sets hp > 750 (kW >560)........................2015+..............................0.500.80

f

................................0.02

f

0.04 

Other Machines hp > 750 (kW >560).......................2015+..............................

j

2.6 j..................................0.03

f

0.05 

7.8

7.1

5.6

5.6

5.6

4.6

4.6

Notes:


a

These are the previous tier NMHC+NOX standards and FEL caps. These levels are not being revised with today’s rule and are printed here 

solely for readers’ convenience. b

These are a combined NMHC+NOX standard and FEL cap. c

A manufacturer may delay implementation until 2010 and then comply with a PM standard of 0.45 g/bhp-hr for air-cooled, hand-startable, di-

rect injection engines under 11 horsepower. d

These FEL caps do not apply if the manufacturer opts out of the 2008 standards. In such cases, the existing Tier 3 standards and FEL caps 

continue to apply. e

The FEL caps apply in model year 2012 if the manufacturer opts out of the 2008 standards. 

f

As described in this section, a small number of engines are allowed to exceed these FEL caps. 

g

For engines certified as phase-out engines, the NMHC+NOX FEL caps for the Tier 3 standards apply. h

For engines certified to the alternative NOX standards during the phase-in, the NOX FEL caps shown in tables III.A–3 and III.A–4 apply. i

The 0.50 g/bhp-hr NOX standard applies only to engines above 1200 horsepower used in generator sets. 

j

The 2011 NOX standard and FEL cap continue to apply unless and until revised by EPA in a future action. 

As noted above, we are allowing a 

limited number of engines to have a 

higher FEL than the caps noted in Table 

III.A–1 in certain instances. The FEL 

cap for such engines would be set based 

on the level of the standards that 

applied in the year prior to the new 

standards and will allow manufacturers 

to produce a limited number of engines 

certified to these earlier standards in the 

Tier 4 timeframe. The allowance to 

certify up to these higher FEL caps will 

apply to Tier 4 engines between 25 and 

750 horsepower beginning as early as 

the 2011 model year, and will apply to 

engines above 750 horsepower starting 

with the 2015 model year. The 

provisions are intended to provide some 

limited flexibility for engine 

manufacturers as they make the 

transition to the aftertreatment-based 

Tier 4 standards while ensuring that the 

vast majority of engines are converted to 

the advanced low-emission technologies 

expected under the Tier 4 program. 

Under the proposal, manufacturers 

would have been allowed to certify at 

levels up to these FEL caps for ten 

percent of its engines in each of the first 

four years after the Tier 4 standards took 

effect and then five percent for 

subsequent years. The California Air 

Resources Board supported the 

proposed allowance. The Engine 

Manufacturers Association commented 

that the percentages of engines allowed 

to the higher FEL caps may not be 

sufficient, noting that it is too early to 

tell if the proposed amounts provided 

enough flexibility. 

In an effort to provide flexibility to 

engine manufacturers while preserving 

the effective number of engines allowed 

to certify at levels up to the higher FEL 

caps, we are revising the proposed 

provisions with today’s action. The 

revised provisions are intended to allow 

manufacturers to produce the same 

number of engines certified to the 

higher FEL caps as would have been 

allowed under the proposal, but provide 

added flexibility in how they distribute 

the allowances over the first four years 

of the transition to the new standards. 

This additional lead time appears 

appropriate, given the potential that a 

limited set of nonroad engines may face 

especially challenging compliance 

difficulties. Under the provisions 

adopted today and subject to the 

limitations explained below, a 

manufacturer would be allowed to 

certify up to 40 percent of its engines 

above the FEL caps shown in Table 

III.A–1 over the first four years the 

aftertreatment-based Tier 4 standards 

take effect (calculated as a cumulative 

total of the percent of engines exceeding 

these FEL caps in each year over the 

four years), with a maximum of 20 

percent allowed in any given year 

(provided the FELs for these engines do 

not exceed levels specified below). 

During this four year period, 

manufacturers would not be required to 

perform transient testing or NTE testing 

on these engines because we expect 

these engines would be carried over 

directly from the previous tier without 

any modification. (NTE testing would 

apply to engines above 750 horsepower 

because the previously applicable set of 

standards required NTE testing.) 

Similarly, for engines between 75 and 

750 horsepower, manufacturers would 

not be required to have closed crankcase 

controls on these engines because we 

also expect that these engines would be 

carried over directly from the previous 

tier without any modification. (Engines 

between 25 and 75 horsepower, and 

engines above 750 horsepower, would 

be required to have closed crankcase 

controls because the previously 

applicable set of standards require 

closed crankcase controls.) 

For the purpose of calculating the 

number of credits such engines would 

use, the manufacturer would include an 

adjustment to the FEL to be used in the 

credit calculation equation. The 

adjustment would be included by 

multiplying the steady-state FEL by a 

Temporary Compliance Adjustment 

Factor (TCAF) of 1.5 for PM and 1.1 for 

NOX. (The NOX TCAF would not apply 

to engines that are not subject to the 

transient testing requirements for NOX 

as discussed in section III.F.) We are 

adopting TCAFs in part to assure in-use 

control of emission from these engines 

in the absence of transient and NTE 

testing, and also to assure that any 

credits these engines use reflect the 
39000 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

level of reductions expected in use. The 

level of the TCAFs are based on data 

from pre-control, Tier 1, and Tier 2 

engines which show that the emissions 

from such engines tested over transient 

test cycles which are more 

representative of real in-use operation 

are higher than emissions from those 

engines tested over the steady-state 

certification test cycle. This is a sales 

weighted version of the Transient 

Adjustment Factor used in the 

NONROAD model. For compliance 

purposes, a manufacturer would be held 

accountable to the unadjusted steadystate FEL established for the engine 

family. 

As proposed, after the fourth year the 

Tier 4 standards apply, the allowance to 

certify engines using the higher FEL 

caps shown in Table III.A–2 will still be 

available but for no more than five 

percent of the engines a manufacturer 

produces in each power category in a 

given year. When the 5 percent 

allowance takes effect, these engines 

will be considered Tier 4 engines and 

all other requirements for Tier 4 engines 

will also apply, including the Tier 4 

NMHC standard, transient testing, NTE 

testing, and closed crankcase controls. 

TCAFs thus do not apply when 

calculating the number of credits such 

engines would use. 

In the two power categories where we 

are adopting phase-in provisions (i.e., 

75 to 175 horsepower engines and 175 

to 750 horsepower engines), the 

allowance to use a higher FEL cap will 

only apply to PM from phase-out 

engines during the phase-in years. We 

originally proposed that the allowance 

to use a higher FEL cap would apply to 

PM from either phase-in or phase-out 

engines during the phase-in years. On 

reflection, this is inconsistent with our 

policy that phase-in engines truly have 

low emissions reflecting use of 

aftertreatment (see also the discussion 

above where we explain that, for the 

same reason, we are adopting a NOX 

FEL cap of 0.60 g/bhp-hr for phase-in 

engines). We consequently are revising 

the proposed allowance so that it is 

available for PM emissions only from 

phase-out engines. As proposed, the 

allowance to use a higher FEL cap for 

NOX will apply starting in 2014 when 

the phase-in period is complete. 

For the power category between 25 

and 75 horsepower, this allowance to 

certify engines at levels up to the higher 

FEL caps will apply beginning with the 

Tier 4 standards taking effect in the 

2013 model year and will apply to PM 

only. For manufacturers choosing to opt 

out of the 2008 model year Tier 4 

standards for engines between 50 and 75 

horsepower and instead comply with 

the Tier 4 standards beginning in 2012, 

the 40% allowance would apply to 

model years 2012 through 2015, and the 

5% allowance would apply to model 

year 2016 and thereafter. The allowance 

to use the higher FEL caps is not 

applicable for the 2008 standards or the 

2013 NMHC+NOX standards for these 

engines because the FEL caps for those 

standards already are set at the level of 

the standard which previously applied. 

For engines above 750 horsepower, 

the allowance to certify a limited 

number of engines at levels up to the 

higher FEL caps would apply beginning 

in model year 2015. (As noted, this is 

because the FEL caps being adopted for 

the 2011 standards for engines above 

750 horsepower are the previous tier PM 

standard and the NOX-only equivalent 

of the previous tier standard.) For NOX, 

the allowance to certify a limited 

number of engines above the FEL cap 

beginning in model year 2015 will apply 

only to engines used in generator sets. 

Engines used in other machines are still 

subject to the model year 2011 NOX 

standard and FEL caps. For PM, the 

allowance to certify a limited number of 

engines above the FEL caps beginning in 

model year 2015 will apply to all 

engines above 750 horsepower. 

Table III.A–2 presents the model 

years, percent of engines, and higher 

FEL caps that will apply under these 

allowances. As noted above, engines 

certified under these higher FEL caps 

during the first four years would not be 

required to perform transient testing or 

NTE testing and engines between 75 and 

750 horsepower would not be required 

to have closed crankcase controls on 

these engines. However, as also noted 

earlier, beginning in the fifth year, when 

the 5 percent allowance takes effect, 

these engines will be considered Tier 4 

engines and all other requirements for 

Tier 4 engines will also apply, including 

the Tier 4 NMHC standard, transient 

testing, NTE testing, and closed 

crankcase controls. 

TABLEIII.A–2.—ALLOWANCEFORLIMITEDUSEOFANFEL CAPHIGHERTHANTHETIER4 FEL CAPS

Power category Model years 

Engines al-

lowed to 

have higher 

FELs (%) 

NOX FEL cap (g/bhp-hr) PM FEL cap (g/bhp-hr) 

25 ≤ hp < 75..............2013–2016

a

................................

b

40Not applicable.............................0.22 

(19 ≤ kW < 56)...........2017+

a

........................................5

75 ≤ hp < 175............2012–2015..................................

b

403.3

c

for hp <100..........................0.30

d

for hp <100 

(56 ≤ kW <130)..........2016+..........................................52.8

c

for hp ≥100..........................0.22

d

for hp ≥100 

175 ≤ hp ≤ 750..........2011–2014..................................

b

402.8

c

.............................................0.15

d

(130 ≤ kW ≤ 560).......2015+..........................................5

>750 hp......................2015–2018..................................

bc

402.6...............................................0.075 

(>560 kW)..................2019+..........................................

e

5.

a

For manufacturers choosing to opt out of the 2008 model year Tier 4 standards for engines between 50 and 75 horsepower and instead com-

ply with the Tier 4 standards beginning in 2012, the 40% allowance would apply to model years 2012 through 2015, and the 5% allowance would 

apply to model year 2016 and thereafter. b

Compliance with the 40% limit is determined by adding the percent of engines that have FELs above the FEL caps shown in Table III.A.–1 in 

each of the four years. A manufacturer may not have more than 20% of its engines exceed the FEL caps shown in Table III.A–1 in any model 

year in any power category. c

The allowance to certify to these higher NOX FEL caps is not applicable during the phase-in period. d

These higher PM FEL caps are applicable to phase-out engines only during the phase-in period. 

e

The limits of 40% or 5% allowed to exceed the NOX FEL cap would apply to engines used in generator sets only. (Engines >750 hp used in 

other machines are allowed to have an NOX FEL as high as 4.6 g/bhp-hr.) The limits of 40% or 5% allowed to exceed the PM FEL cap would 

apply to all engines above 750 hp. 

Under the Tier 4 program, there will 	 horsepower engines during the NOX out engines’’), engines will certify to the 

be two different groups of 75–750 phase-in period. In one group (‘‘phase- applicable Tier 3 NMHC+NOX standard
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 39001 

and will be subject to the NMHC+NOX 

ABT restrictions and allowances 

previously established for Tier 3. In the 

other group (‘‘phase-in engines’’), 

engines will certify to the 0.30 g/bhp-hr 

NOX standard, and will be subject to the 

restrictions and allowances in this 

program. Although engines in each 

group are certified to different 

standards, we are (as proposed) 

allowing manufacturers to transfer 

credits across these two groups of 

engines with the following adjustment 

to the amount of credits generated. 

Manufacturers will be able to use credits 

generated during the phase-out of 

engines subject to the Tier 3 

NMHC+NOX standard to average with 

engines subject to the 0.30 g/bhp-hr 

NOX standard, but these credits will be 

subject to a 20 percent discount, the 

adjustment reflecting the NMHC 

contribution. Thus, each gram of 

NMHC+NOX credits from the phase-out 

engines will be worth 0.8 grams of NOX 

credits in the new ABT program. The 

ability to average credits between the 

two groups of engines will give 

manufacturers a greater opportunity to 

gain experience with the low-NOX 

technologies before they are required to 

meet the final Tier 4 standards across 

their full production. The 20 percent 

discount will also apply, for the same 

reason, to all NMHC+NOX credits used 

for averaging purposes with the NOX 

standards for engines greater than 75 

horsepower. 

The California Air Resources Board 

supported the proposed discount of 20 

percent on NMHC+NOX credits used for 

NOX compliance. The Engine 

Manufacturer’s Association commented 

that we should eliminate the 20 percent 

‘‘discount’’ on NMHC+NOX credits used 

for NOX compliance. 

We disagree with the Engine 

Manufacturer’s Association comments. 

As noted in the proposal, we have two 

main reasons for adopting this 

adjustment. First, the discounting 

addresses the fact that NMHC 

reductions can provide substantial 

NMHC+NOX credits, which are then 

treated as though they were NOX 

credits. For example, a 2010 model year 

175 horsepower engine emitting at 2.7 

g/bhp-hr NOX and 0.3 g/bhp-hr NMHC 

meets the 3.0 g/bhp-hr NMHC+NOX 

standard in that year, but gains no 

credits. In 2011, that engine, equipped 

with a PM trap to meet the new PM 

standard, will have very low NMHC 

emissions because of the trap, an 

emission reduction already accounted 

for in our assessment of the air quality 

benefit of this program. As a result, 

without substantially redesigning the 

engine to reduce NOX or NMHC, the 

manufacturer could garner nearly 0.3 g/ 

bhp-hr of NMHC+NOX credit for each of 

these engines produced. Allowing these 

NMHC-derived credits to be used 

undiscounted to offset NOX emissions 

on the phase-in engines in 2011 (for 

which each 0.1 g/bhp-hr of margin can 

make a huge difference in facilitating 

the design of engines to meet the 0.30 

g/bhp-hr NOX standard) would be 

inappropriate. Therefore, while we are 

reducing the value of credits earned 

from Tier 2/Tier 3 engines, the 

adjustment accounts for the NMHC 

fraction of the credits which we do not 

believe should be used to demonstrate 

compliance with the NOX-only Tier 4 

standards (such credits would be 

‘‘windfalls’’ because they would 

necessarily occur by virtue of the 

technology needed to meet the PM 

standard) (68 FR 28469, May 23, 2003). 

Second, the discounting will work 

toward providing a small net 

environmental benefit from the ABT 

program, such that the more 

manufacturers use banked and averaged 

credits, the greater the potential 

emission reductions overall. Most 

basically, it is inherently reasonable, in 

using NOX+NMHC reductions to show 

credit with a NOX-only standard, to use 

only that portion which represents NOX 

reductions. (Indeed, for this reason, 

terming the 20 per cent a ‘‘discount 

factor’’ is a misnomer; it apportions the 

NMHC fraction of the reduction.) As 

noted, this is further supported by the 

fact that the NMHC reductions for 

phase-out engines are not extra 

reductions above and beyond what 

would otherwise occur, and therefore 

don’t warrant eligibility as credits. 

We are adopting one additional 

restriction on the use of credits under 

the ABT program. For the Tier 4 

standards, we proposed that 

manufacturers could only use credits 

generated from other Tier 4 engines or 

from engines certified to the previously 

applicable tier of standards (i.e., Tier 2 

for engines below 50 horsepower, Tier 

3 for engines between 50 and 750 

horsepower, and Tier 2 engines above 

750 horsepower). This proposed 

restriction was similar to a restriction 

we currently have that prohibits the use 

of Tier 1 credits to demonstrate Tier 3 

compliance. STAPPA/ALAPCO and the 

Natural Resources Defense Council 

supported the proposed approach that 

limited the use of previous-tier credits 

for Tier 4. The Engine Manufacturer’s 

Association commented that by limiting 

the use of previous-tier credits, we are 

engaged in an unconstitutional taking 

because EPA had guaranteed in the 

previous Tier 2/Tier 3 rulemaking that 

such credits would not expire. We 

disagree that adopting a restriction on 

the use of the previous tier ABT credits 

is an unconstitutional taking. EPA did 

not, and could not, decide in the Tier 2/ 

3 rulemaking that Tier 2/3 credits could 

be used to show compliance with some 

future standards that had not yet even 

been adopted. Thus, EPA in this 

rulemaking is not taking away 

something previously given. We are not 

revisiting the Tier 2/3 standards but 

establishing a new set of engine 

standards. In doing so, we necessarily 

must evaluate the provisions of previous 

rules and their potential impact on the 

future standards being considered. We 

are reasonably concerned that credits 

from engines certified to relatively high 

standards could be used to significantly 

delay the implementation of the final 

Tier 4 program and its benefits, 

resulting in a situation where the 

standards would no longer reflect the 

greatest degree of emission reduction 

available as required under section 

213(a)(3) of the Clean Air Act, or would 

no longer be appropriate under section 

213(a)(4) of the Clean Air Act. 

Therefore, with today’s action, we are 

adopting the proposed provisions 

regarding the use of credits from 

previous tier engines, with one minor 

revision. 

Under today’s action, manufacturers 

may only use credits generated from 

other Tier 4 engines or from engines 

certified to the previously applicable 

tier of standards—except for engines 

between 50 and 75 horsepower. Because 

we are adopting Tier 4 standards that 

take effect as early as 2008 for those 

engines, the same year the previouslyadopted Tier 3 standards are scheduled 

to take effect (see section II.A.1.a above), 

there is no possibility to earn credits 

against the Tier 3 standards for 

manufacturers that certify with the pullahead standards in 2008 for engines 

between 50 and 75 horsepower. 

Therefore, we will allow manufacturers 

to use credits from engines in the Tier 

2 power category that includes 50 to 75 

horsepower (i.e., the 50 to 100 

horsepower category) that are certified 

to the Tier 2 standards if they choose to 

demonstrate compliance with the pullahead Tier 4 standards in 2008 for 

engines between 50 and 75 horsepower. 

Manufacturers that do not choose to 

comply with the 2008 Tier 4 standards 

for engines between 50 and 75 

horsepower and instead comply with 

the 2012 Tier 4 standards for such 

engines will not be allowed to use Tier 

2 credits in Tier 4, but instead will be 

allowed to use Tier 3 credits as allowed 

under the standard provisions regarding 
39002 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

use of previous-tier credits only for Tier 

4 compliance demonstration. 

With regard to other restrictions on 

the use of ABT credits, we are adopting 

one restriction on the use of credits 

across the 750 horsepower threshold. In 

previous rulemakings, EPA has defined 

‘‘averaging sets’’ within which 

manufacturers may use credits under 

the ABT program. Credits may not be 

used outside of the averaging set in 

which they were generated. As 

described in section II.A.4 of today’s 

action, we have revised the Tier 4 

standards for engines above 750 

horsepower. Because the standards for 

Tier 4 engines greater than 750 

horsepower will not be based on the use 

of PM aftertreatment technology in 2011 

or NOX aftertreatment technology for all 

mobile machinery engines in 2015, we 

are adopting provisions that prevent 

manufacturers from using credits from 

model year 2011 and later model year 

engines greater than 750 horsepower to 

demonstrate compliance with engines 

below 750 horsepower. Without such a 

limit, we are concerned that 

manufacturers could use credits from 

such engines to significantly delay 

compliance with the numerically lower 

standards for engines below 750 

horsepower. In addition, without such a 

limit, we are concerned that 

manufacturers could use credits from 

engines below 750 horsepower to delay 

implementation of aftertreatment 

technology for engines above 750 

horsepower. 

One engine manufacturer commented 

that EPA should include a barrier to 

trading credits across the 75 horsepower 

level. They cited concerns over the 

ability of manufacturers that produce a 

large range of engine sizes to use credits 

from high horsepower engines to offset 

emissions from their small horsepower 

engines. We are not adopting any 

averaging set restrictions for Tier 4 

engines below 750 horsepower in 

today’s action. In the current nonroad 

diesel ABT program, there are averaging 

set restrictions. The current averaging 

sets consist of engines less than 25 

horsepower and engines greater than or 

equal to 25 horsepower. We adopted 

this restriction because of concerns over 

the ability of manufacturers to generate 

significant credits from the existing 

engines and use the credits to delay 

compliance with the newly adopted 

standards (63 FR 56977, October 23, 

1998). We believe the Tier 4 standards 

for engines below 750 horsepower are 

sufficiently rigorous to limit the ability 

of manufacturers to generate significant 

credits from their engines. In addition, 

we believe the FEL caps being adopted 

today provide sufficient assurance that 

low-emissions technologies will be 

introduced in a timely manner. 

Therefore, we believe averaging can be 

allowed between all engine power 

categories below 750 horsepower 

without restriction effective with the 

Tier 4 standards. (It should be noted 

that the averaging set restriction placed 

on credits generated from Tier 2 and 

Tier 3 engines will continue to apply if 

they are used to demonstrate 

compliance for Tier 4 engines.) 

EPA also proposed to allow engine 

manufacturers to demonstrate 

compliance with the NOX phase-in 

requirements by certifying evenly split 

engine families at, or below, specified 

NOX FELs (68 FR 28470, May 23, 2003). 

As described in section II.A.2.c above, 

EPA is revising the evenly split family 

provisions for the Tier 4 program and is 

now codifying them as alternative 

standards. (As described in section III.L, 

we also are adopting the proposed 

provisions allowing manufacturers to 

certify ‘‘split’’ engine families during 

the phase-in years.) Because the evenly 

split family provision has evolved into 

a set of alternative NOX standards, we 

believe it is appropriate to allow 

manufacturers to use ABT for them. 

Table III.A–3 presents the FEL caps that 

will apply to engines certified to the 

alternative NOX standards during the 

phase-in years. The FEL caps for these 

alternative standards have been set at 

levels reasonably close to the alternative 

standards and are intended to ensure 

sizeable emission reductions from the 

previously-applicable Tier 3 standards. 

(For engines between 75 and 175 

horsepower certified under the reduced 

phase-in option, the FEL cap is the 

NOX-only equivalent of the previously 

applicable NMHC+NOX standards 

because the alternative standard is 

sufficiently close to the Tier 3 standard.) 

TABLEIII.A–3.—NOX FEL CAPSFORENGINESCERTIFIEDTOTHEALTERNATIVENOX STANDARDS

Power category 

Alternative 

NOX standard 

(g/bhp-hr) 

NOX FEL cap (g/bhp-

hr) 

50/50/100 phase-in option for 75 ≤ hp < 175 (56 ≤ kW <130)...................................................................1.72.2. 

25/25/25/100 phase-in option for 75 ≤ hp < 175 (56 ≤ kW <130)..............................................................2.53.3 (for 75–100 hp). 

2.8 (for 100–175 hp) 

175 ≤ hp ≤ 750 (130 ≤ kW ≤ 560)...............................................................................................................1.52.0. 

Because we are allowing 40 percent over the first four years the NMHC+NOX standards. For 

manufacturers to use ABT for Tier 4 standards take effect as described manufacturers certifying under the 

demonstrating compliance with the earlier). Table III.A–4 presents the NOX reduced phase-in (25 percent) option, 

alternative standards for engines FEL caps that would apply to engines because the FEL caps are the NOX-only between 75 and 750 horsepower, we are certified under the alternative standards equivalent of the Tier 3 NMHC+NOX 

allowing manufacturers to exceed the (limited by the 40 percent cap over the standards, they may not exceed the FEL FEL caps noted in table III.A–3 and first four years). The higher NOX FEL cap during the years the alternative include them in the count of engines caps are set at the estimated NOX-only standard applies. allowed to exceed the FEL caps (i.e., the equivalent of the previous-tier 

TABLEIII.A–4.—LIMITED-USENOX FEL CAPSUNDERTHEALTERNATIVENOX STANDARDS

Power category Model years NOX FEL cap (g/bhp-

hr) 

50/50/100 phase-in option for 75 ≤ hp < 175a............................................................................................2012–20133.3 for hp <100. 

(56 ≤ kW <130)............................................................................................................................................2.8 for hp ≥100. 

175 ≤ hp ≤ 750............................................................................................................................................2011–20132.8. 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 39003 

TABLEIII.A–4.—LIMITED-USENOX FEL CAPSUNDERTHEALTERNATIVENOX STANDARDS—Continued

Power category Model years NOX FEL cap (g/bhp-

hr) 

(130 ≤ kW ≤ 560).........................................................................................................................................

For reasons explained in section 

II.A.1.b.i above, we are also adopting 

unique phase-in requirements for NOX 

standards for engines between 75 and 

175 horsepower in order to ensure 

appropriate lead time for these engines. 

Because of these unique phase-in 

provisions, as proposed, we are 

adopting slightly different provisions 

regarding 75 to 175 horsepower engines’ 

use of previous-tier credits. Under 

today’s action, manufacturers that 

choose to demonstrate compliance with 

these phase-in requirements (i.e., 50 

percent in 2012 and 2013 and 100 

percent in 2014) or the 1.7 g/bhp-hr 

alternative NOX standard (which is 

based on the 50 percent phase-in 

option) will be allowed to use Tier 2 

NMHC+NOX credits generated by 

engines between 50 and 750 horsepower 

(even though they are not generated by 

previous-tier engines), along with any 

other allowable credits, to demonstrate 

compliance with the Tier 4 NOX 

standards for engines between 75 and 

175 horsepower during model years 

2012, 2013 and 2014 (the years of the 

phase-in) only. These Tier 2 credits will 

be subject to the power rating 

conversion already established in our 

ABT program, and to the 20% credit 

adjustment being adopted today for use 

of NMHC+NOX credits as NOX credits. 

The requirements for manufacturers 

that choose to demonstrate compliance 

with the optional reduced phase-in 

requirement for engines between 75 and 

175 horsepower (i.e, the 25/25/25 

percent phase-in option; see Table II.A.– 

2, note b) or the 2.5 g/bhp-hr alternative 

NOX standard (which is based on the 25 

percent phase-in option) are different. 

Under the reduced phase-in 

requirement, use of credits will be 

allowed in accordance with the general 

ABT program provisions. In other 

words, manufacturers will not have the 

special allowance to use Tier 2 

NMHC+NOX credits generated by 

engines between 50 and 750 horsepower 

noted above to demonstrate compliance 

with the Tier 4 standards. In addition, 

manufacturers choosing the reduced 

phase-in option will not be allowed to 

generate NOX credits from engines in 

this power category in 2012, 2013, and 

most of 2014, except for use in 

averaging within this power category 

(i.e., no banking or trading, or averaging 

with engines in other power categories 

will be permitted). This restriction will 

apply throughout this period even if the 

reduced phase-in option is exercised 

during only a portion of this period. We 

believe that this restriction is important 

to avoid potential abuse of the added 

flexibility allowance, considering that 

larger engine categories will be required 

to demonstrate substantially greater 

compliance levels with the 0.30 g/bhphr NOX standard several years earlier 

than engines built under the reduced 

phase-in option. 

As described in section II.A.3.a of 

today’s action, and as proposed, we are 

adopting an optional PM standard for 

air-cooled, hand-startable, direct 

injection engines under 11 horsepower 

effective in 2010. In order to avoid 

potential abuse of this standard, engines 

certified under this requirement will not 

be allowed to generate any credits as 

part of the ABT program. Credit use by 

these engines will be allowed. The 

restriction on generating credits should 

not be a burden to manufacturers, as it 

will apply only to those air-cooled, 

hand-startable, direct injection engines 

under 11 horsepower that are certified 

under the optional approach, and the 

production of credit-generating engines 

would be contrary to the standard’s 

purpose. No adverse comments were 

submitted to EPA on this issue. 

The current ABT program contains a 

restriction on trading credits generated 

from indirect injection engines greater 

than 25 horsepower. The restriction was 

originally adopted because of concerns 

over the ability of manufacturers to 

generate significant credits from existing 

technology engines (63 FR 56977, 

October 23, 1998). With today’s action, 

there will be no restriction prohibiting 

manufacturers from trading credits 

generated on Tier 4 indirect fuel 

injection engines greater than 25 

horsepower. Based on the certification 

levels of indirect injection engines, we 

do not believe there is the potential for 

manufacturers to generate significant 

credits from their currently certified 

engines against the Tier 4 standards. 

Therefore, as proposed, we are not 

adopting any restrictions on the trading 

of credits generated on Tier 4 indirect 

injection engines to other 

manufacturers. The restriction placed 

on the trading of credits generated from 

Tier 2 and Tier 3 indirect injection 

engines will continue to apply in the 

Tier 4 timeframe. No adverse comments 

were submitted to EPA on this issue. 

As explained in the proposal, we are 

not applying a specific discount to Tier 

3 PM credits used to demonstrate 

compliance with the Tier 4 standards 

(68 FR 28471, May 23, 2003). PM credits 

generated under the Tier 3 standards are 

based on testing performed over a 

steady-state test cycle. Under the Tier 4 

standards, the test cycle is being 

supplemented with a transient test (see 

section III.F.1 below). Because in-use 

PM emissions from Tier 3 engines will 

vary depending on the type of 

application in which the engine is used 

(most applications having higher in-use 

PM emissions, some having lower inuse PM emissions), the relative ‘‘value’’ 

of the Tier 3 PM credits in the Tier 4 

timeframe will differ. Instead of 

requiring manufacturers to gather 

information to estimate the level of inuse PM emissions compared to the PM 

level of the steady-state test, we believe 

allowing manufacturers to bring Tier 3 

PM credits directly into the Tier 4 time 

frame without any adjustment is 

appropriate because it discounts their 

value for use in the Tier 4 timeframe 

(since the initial baseline being reduced 

is higher than measured in the Tier 2 

test procedure for most applications). 

No adverse comments were submitted to 

EPA on this issue. 

3. Are We Expanding the Nonroad ABT 

Program To Include Credits From 

Retrofit of Nonroad Engines? 

In the proposal, we requested 

comment on expanding the scope of the 

standards by setting voluntary new 

engine emission standards applicable to 

the retrofit of nonroad diesel engines (68 

FR 28471, May 23, 2003). As described 

in the proposal, retrofit nonroad engines 

would be able to generate PM and NOX 

credits which would be available for use 

by new nonroad engines in the 

certification ABT program. We received 

a significant number of comments on a 

retrofit ABT program. A number of 

commenters associated with the 

agricultural sector were concerned 

retrofits would be mandatory. Some 

commenters were opposed to a retrofit 

credit program that would allow use of 

the credits under the certification ABT 

program. However, a number of 

commenters supported the concept of a 

retrofit program, but noted a number of 
39004 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

concerns regarding the details of such a 

program, including making sure that 

any credits earned would be verifiable 

and enforceable. Some commenters 

suggested that EPA consider the 

establishment of a retrofit credit 

program through a separate rulemaking 

because there were many details of the 

program that needed to be explored 

more fully before adopting such a 

program. In response to the comments, 

we are not adopting a retrofit credit 

program with today’s action. Although 

we provided a detailed explanation of a 

potential program at proposal, 62 we 

believe it is important to more fully 

consider the details of a nonroad engine 

retrofit credit program and work with 

interested parties in determining 

whether a viable program can be 

developed. EPA intends to explore the 

possibility of a voluntary, opt-in 

nonroad retrofit credit program through 

a separate action later this year. Such a 

program would be based on the 

generation of credits beyond the scope 

of any existing retrofit program. The 

final rule contains no requirements for 

retrofitting existing engines or 

equipment. 

B. Transition Provisions for Equipment 

Manufacturers 

1. Why Are We Adopting Transition 

Provisions for Equipment 

Manufacturers? 

As EPA developed the 1998 Tier 2/3 

standards for nonroad diesel engines, 

we determined, as an aspect of 

determining an appropriate lead time 

for application of the requisite 

technology (pursuant to section 213(b) 

of the Act), that provisions were needed 

to avoid unnecessary hardship and to 

create additional flexibility for 

equipment manufacturers. The specific 

concern is the amount of work required 

and the resulting time needed for 

equipment manufacturers to incorporate 

all of the necessary equipment redesigns 

into their applications in order to 

accommodate engines that meet the new 

emission standards. We therefore 

adopted a set of provisions for 

equipment manufacturers to provide 

them with reasonable lead time for the 

transition process to the newly adopted 

standards. The program consisted of 

four major elements: (1) A percent-ofproduction allowance, (2) a smallvolume allowance, (3) availability of 

hardship relief, and (4) continuance of 

the allowance to use up existing 

inventories of engines (63 FR 56977– 

62 See memorandum referenced at 68 FR 28471 

(May 23, 2003), footnote 299. 

56978, October 23, 1998 and 68 FR 

28472–28476, May 23, 2003). 

Given the levels of the newly adopted 

Tier 4 standards, we believe that there 

will be engine design and other changes 

at least comparable in magnitude to 

those involved during the transition to 

Tier 2/3. Therefore, with a few 

exceptions described in more detail 

below, we are adopting transition 

provisions for Tier 4 that are similar to 

those adopted with the previous Tier 2/ 

3 rulemaking. We also note that 

opportunities for greater flexibility 

arises from the structure of the Tier 4 

rule. For example, Tier 4 consolidates 

the nine power categories in Tier 2/3 

into five categories, providing 

opportunities for more flexibility by 

allowing more engine families within 

each power category, with consequent 

increased averaging possibilities. The 

NOX phase-in also provides increased 

flexibility opportunities, as do the 

longer Tier 4 lead times. 

We are adding new notification, 

reporting, and labeling requirements to 

the Tier 4 program. We believe these 

additional provisions are necessary for 

EPA to gain a better understanding of 

the extent to which these provisions 

will be used and to ensure compliance 

with the Tier 4 transition provisions. 

We are also adopting new provisions 

dealing specifically with foreign 

equipment manufacturers and the 

special concerns raised by the use of the 

transition provisions for equipment 

imported into the U.S. The following 

section describes the Tier 4 transition 

provisions available to equipment 

manufacturers. (Section III.C of this 

preamble describes all of the provisions 

that will be available specifically for 

small businesses.) 

As under the existing Tier 2/Tier 3 

provisions, equipment manufacturers 

are not obligated to use any of these 

provisions, but all equipment 

manufacturers are eligible to do so. 

Also, as under the existing program, all 

entities under the control of a common 

entity, and that meet the regulatory 

definition of a nonroad vehicle or 

nonroad equipment manufacturer, must 

be considered together for the purpose 

of applying exemption allowances. This 

will not only provide certain benefits for 

the purpose of pooling exemptions, but 

will also preclude the abuse of the 

small-volume allowances that would 

exist if companies could treat each 

operating unit as a separate equipment 

manufacturer. 

2. What Transition Provisions Are We 

Adopting for Equipment Manufacturers? 

The following section describes the 

transition provisions being adopted 

with today’s action. Areas in which we 

have made changes to the proposed 

transition program are highlighted. A 

complete summary of comments 

received on the proposed transition 

program and our response to those 

comments are contained in the 

Summary and Analysis of Comments 

document for this rule. 

EPA believes that the lead time 

provided through the equipment maker 

transition flexibilities, as adopted in this 

rule, will be sufficient, as has proved 

the case in past tiers. These flexibilities 

provide equipment manufacturers with 

the selective ability to delay use of the 

Tier 4 engines in those applications 

where additional time is needed to 

successfully incorporate the redesigned 

engines into their equipment. 

Ingersoll-Rand, an equipment 

manufacturer, submitted a number of 

comments arguing that significant 

expansions of the proposed flexibility 

program are needed if equipment 

manufacturers are to produce compliant 

applications within the effective dates 

of the standards. One suggestion was for 

EPA to include provisions that provide 

a definitive period of lead time for 

incorporation of Tier 4 engines into 

nonroad equipment. Ingersoll-Rand 

would have the rules specify a ‘‘made 

available’’ date before which each 

engine supplier must provide technical 

and performance specifications, 

complete drawings, and a final 

compliant engine to EPA and the open 

market. After the mandated ‘‘made 

available’’ date, equipment 

manufacturers should be provided a 

minimum 18 months of lead time to 

incorporate the new engines into 

nonroad equipment. One form of the 

suggestion also entailed a prohibition on 

design changes once the engine, 

specifications, drawings, etc. had been 

initially provided to EPA and to the 

open market. As an alternative, 

Ingersoll-Rand urged that the percent of 

production allowance flexibility be 

expanded to 150 percent for the power 

categories between 75 and 750 

horsepower and 120 percent for the 

power category between 25 and 75 

horsepower. Ingersoll-Rand believes 

these levels correspond proportionately 

to the increased challenges facing 

equipment manufacturers during Tier 4 

as opposed to Tier 2 and Tier 3. 

As discussed in greater detail in the 

Summary and Analysis of Comments, as 

well as in later parts of this section of 

this preamble and elsewhere in the 

administrative record, we disagree with 

most of Ingersoll-Rand’s suggestions. 

Our fundamental disagreement is with 

Ingersoll-Rand’s premise that Tier 4 will 

create a situation where need for 
Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 39005 

expanded equipment maker lead time is 

the norm rather than the exception so 

that the rule must provide a drastic, 

across-the-board expansion of 

equipment manufacturer lead time. We 

believe that the lead time provided for 

equipment makers in this rule is 

adequate, and that the equipment maker 

flexibilities we are adopting provide a 

reasonable and targeted safety valve to 

deal with isolated problems. There is no 

across-the-board problem necessitating a 

drastic expansion of equipment 

manufacturer lead time, or a drastic 

expansion of equipment manufacturer 

flexibilities. We base these conclusions 

largely on three factors: (a) Our 

investigation and understanding of the 

engineering process by which engine 

makers and equipment manufacturers 

bring new products to market; (b) the 

specific engineering challenges which 

equipment manufacturers will address 

in complying with the Tier 4 rule; and 

(c) past practice of equipment 

manufacturers under previous rules 

providing transition flexibilities for 

nonroad equipment. 

Because it is in both parties’ interest 

for new engines and new equipment 

applications to reach the market 

expeditiously, engine makers and 

equipment manufacturers usually adopt 

concurrent engineering programs 

whereby the new equipment design 

process occurs simultaneous to the new 

engine development process. We believe 

that this concurrent process should 

work well for Tier 4 because, in many 

important ways, the engineering 

challenges facing equipment 

manufacturers can be anticipated and 

dealt with early in the design process. 

We expect that relatively early in the 

design process, engine manufacturers 

will be able to define the size and 

characteristics of the emission control 

technologies (e.g., NOX adsorbers and 

CDPFs), based on the same systems that 

will be in production for on-highway 

engines. The equipment manufacturers 

will concurrently redesign their 

equipment to accommodate these new 

technologies, including designing, 

mounting and supporting the catalytic 

equipment similar to current exhaust 

muffler systems. 

Moreover, while we expect the 

redesign challenge for Tier 4 equipment 

to be similar to that for Tier 2/3, we also 

expect the redesign to be better and 

more clearly defined well in advance of 

the Tier 4 introduction dates. This is 

because we do not expect the catalyst 

system size or shape to change 

significantly during the last 24 months 

of the engine design and validation 

process.63 

We also have studied the extent to 

which equipment manufacturers have 

used their flexibilities under the Tier 2/ 

3 program. Although at an early stage in 

the Tier 2/3 process, initial indications 

are that the flexibility program is being 

used by many equipment 

manufacturers, but in general, 

manufacturers do not appear to be using 

the full level of allowances.64 It appears 

that the flexibilities are being used as 

EPA intended, providing manufacturers 

with flexibility to deal with specific 

limited situations, rather than to deal 

with an across-the-board problem. 

The emerging pattern is thus the one 

on which the flexibility program is 

predicated: there is not a need for 

across-the-board drastic expansion of 

equipment manufacturer lead time. 

Indeed, such an expansion would be 

inconsistent with the lead time-forcing 

nature of section 213 (b) of the Act. This 

is not to say that there is no need for 

equipment manufacturer flexibilities, or 

that the Tier 2/3 flexibility format need 

not be adjusted to accommodate 

potential problems to be faced under the 

Tier 4 regime. Instances where 

additional lead time could be justified 

are where resource constraints prevent 

completion of certain applications, or 

where for business reasons it makes 

sense for equipment manufacturers to 

delay completion of small volume 

families in order to complete larger 

volume equipment applications. In 

addition, the Tier 2/3 experience 

illustrates that there can be instances 

where emission control optimization 

which necessitates equipment design 

changes occurs late in the design cycle, 

resulting in a need for additional 

equipment manufacturer lead time. The 

equipment manufacturer flexibilities 

adopted in today’s rule accommodate 

these possibilities. 

We have specific objections to 

Ingersoll-Rand’s preferred approach of a 

mandated made available date, followed 

by 18 months of additional lead time for 

equipment manufacturers. 

Superimposing a government mandate 

on the engine maker—equipment 

manufacturer business relationship 

insinuates EPA into the middle of 

contractual/market relationships (e.g., 

when is an objectively reasonable 

delivery date?), forcing EPA to prejudge 

myriad differing business relationships/ 

engineering situations. Moreover, 

63 ‘‘Tier 4 Nonroad Diesel Equipment Flexibility 

Provisions,’’ memorandum from Byron Bunker, et 

al., (EPA) to EPA Air Docket OAR–2003–0012. 

64 ‘‘Tier 4 Nonroad Diesel Equipment Flexibility 

Provisions,’’ memorandum from Byron Bunker, et 

al., (EPA) to EPA Air Docket OAR–2003–0012. 

selection of any single made available 

date is bound to be arbitrary in most 

situations. We also believe that the 18-

month lead time following a made 

available date entails a mandated 18-

month period (at least) with no return 

on investment to engine suppliers (i.e. 

the period between when the Tier 4 

engine would be produced and when it 

could lawfully be sold), which would 

increase the engine cost, and discourage 

design changes (since such changes 

would entail more investment with 

delayed return on that investment). The 

ultimate result would be a costlier rule 

and less environmental benefit due to 

the delay in introducing Tier 4 engines. 

Even were EPA to put forth such a 

regulation, it is not clear that it could be 

enforced or that it would help the 

situation. It would only be natural for 

engine manufacturers to continue to 

improve its products even after the 

predefined ‘‘made available date’’ and 

equipment manufacturers would want 

to use this improved product even if it 

meant they had to make last minute 

changes to the equipment design. For 

EPA to preclude engine manufacturers 

from changing their product designs 

over the period between the certification 

date and the equipment manufacturer 

date would be both unusual and 

counterproductive to our goal of seeing 

the best possible products available in 

the market. Moreover, EPA sees no need 

to interfere with the concurrent design 

market mechanism, which allows 

engine makers and equipment 

manufacturers to negotiate optimal 

solutions. We believe it is better to leave 

to the market participants the actual 

decision for how and when to conduct 

concurrent engineering designs. 

The California Air Resources Board 

commented that EPA should eliminate 

or reduce the amount of flexibilities 

provided for less than 25 horsepower 

engines, because the Tier 4 engine 

standards are not aftertreatment-based. 

The Engine Manufacturers Association 

commented that we should expand the 

amount of flexibilities for engines 

greater than 750 horsepower, given the 

difficulty of complying with the 

proposed standards for engines above 

750 horsepower. With today’s action, 

we are applying the same flexibility for 

all power categories, including engines 

below 25 horsepower and engines above 

750 horsepower. While it is true that the 

Tier 4 standards for engines below 25 

horsepower are not aftertreatmentbased, we believe there will be changes 

in engine design for many of those 

engines in response to the Tier 4 

standards. As engine designs change, 

there is the potential for impacts on 
39006 Federal Register / Vol. 69, No. 124 / Tuesday, June 29, 2004 / Rules and Regulations 

equipment design as well (as shown in 

implementing the Tier 2/3 rule). 

Therefore, we believe providing 

equipment manufacturer flexibility for 

engines below 25 horsepower is 

appropriate and we are adopting the 

same flexibilities for engines below 25 

horsepower as for other power 

categories. With regard to engines above 

750 horsepower, we are retaining the 

same flexibilities for those engines as for 

other power categories. As described in 

section II.A.4, the Tier 4 standards being 

adopted today for engines above 750 

horsepower have been revised from the 

proposal. We believe that these 

revisions have appropriately 

accommodated concerns for the most 

difficult to design applications (i.e., 

NOX adsorbers for engines in mobile 

applications), so that additional 

equipment flexibilities are not 

warranted for these engines. 

The Engine Manufacturers 

Association commented that some 

equipment manufacturers may be 

capable of making an on-time transition 

to the interim Tier 4 standards (e.g. the 

2011 standards applicable for 175–750 

horsepower engines) without the use of 

flexibilities. Such equipment 

manufacturers would like the ability to 

start the seven-year period in which 

they may use flexibilities in the year the 

final Tier 4 standards (the 

aftertreatment-based standards for both 

PM and NOX) take effect. Put another 

way, they would not need more lead 

time for equipment to meet the interim 

standards, but could need more lead 

time for equipment required to meet the 

final standards. In addition, the 

commenter suggested a modified 

approach that could lead to earlier 

emission reductions than under the 

proposed rule: Requiring delayed 

flexibility engines to meet the interim 

Tier 4 standards instead of meeting the 

Tier 2/3 standards (as would have been 

allowed under the proposal if the 

flexibilities started in the first year of 

the interim Tier 4 standards). 

EPA wants to encourage the 

implementation of the Tier 4 standards 

as early as possible. Therefore, we 

believe it makes sense to provide 

incentives to equipment manufacturers 

to use interim Tier 4 compliant engines 

in their equipment during the transition 

to the final Tier 4 standards. Moreover, 

it is reasonable to expect that more lead 

time will be needed for the 

aftertreatment-based standards than for 

the interim standards. Therefore, in 

response to these comments, we are 

revising the proposed flexibility 

provisions to allow equipment 

manufacturers to have the option of 

starting the seven-year period in which 

flexibility engines may be used in either 

the first year of the interim Tier 4 

standards or the first year of the final 

Tier 4 standards. For engines between 

25 and 75 horsepower, the final Tier 4 

standards may begin in 2012 or 2013 

depending on whether the manufacturer 

chooses to comply with the interim 

2008 Tier 4 standards. An equipment 

manufacturer who does not use 

flexibilities in 2008 thus may need 

flexibilities as early as 2012. Therefore, 

the seven-year period for the final Tier 

4 standards for engines between 25 and 

75 horsepower will begin in 2012 

instead of 2013. Moreover, it is clearly 

appropriate that these delayed 

flexibility engines meet the interim Tier 

4 standards, in order not to backslide 

from existing levels of performance. 

Table III.B–1 shows the years in 

which manufacturers could choose to 

start the Tier 4 flexibilities given the 

standards being adopted today. (The 

seven-year period for engines below 25 

horsepower takes effect in 2008 as 

proposed, because there are no interim 

standards for such engines.) 

TABLEIII.B–1.—FLEXIBILITYPERIODSFORTHETIER4 STANDARDS

Power category 

Model year

flexibility

period

options 

Standards to which flexibility en-

gines would have to certify 

25 ≤ hp < 75...........................................................................................................................2008–2014 Tier 2 standards. 

(19 ≤ kW < 56).......................................................................................................................2012–2018 Model Year 2008 Tier 4 standards. 

75 ≤ hp < 175.........................................................................................................................2012–2018 Tier 3 standards. 

(56 ≤ kW <130)......................................................................................................................2014–2020 Model Year 2012 Tier 4 standards. 

175 ≤ hp ≤ 750.......................................................................................................................2011–2017 Tier 3 standards. 

(130 ≤ kW ≤ 560)...................................................................................................................2014–2020 Model Year 2011 Tier 4 standards. 

>750 hp..................................................................................................................................2011–2017 Tier 2 standards. 

(>560 kW)...............................................................................................................................2015–2021 Model Year 2011 Tier 4 standards. 

Under today’s action, and as 

proposed, only those nonroad 

equipment manufacturers that install 

engines and have primary responsibility 

for designing and manufacturing 

equipment will qualify for the 

allowances or other relief provided 

under the Tier 4 transition provisions. 

As a result of this definition, importers 

that have little involvement in the 

manufacturing and assembling of the 

equipment will be ineligible to receive 

any allowances. The Engine 

Manufacturers Association and one 

engine manufacturer commented that 

the proposed definition of equipment 

manufacturer needed to be revised to 

cover situations in which a 

manufacturer contracts out the design 

and production of equipment to another 

manufacturer. While we understand 

there are many different types of 

relationships between equipment 

manufacturers, we believe it is 

important to establish firm criteria for 

determining eligibility to use the 

equipment manufacturer allowances. 

We are concerned that the change to the 

equipment manufacturer definition 

suggested by the commenters would 

allow entities that have little or no 

involvement in the actual design, 

manufacture and assembly of equipment 

(e.g., companies that only import 

equipment) to claim they contracted 

with an equipment manufacturer to 

produce equipment for them and 

therefore claim allowances. This is the 

exact situation we are attempting to 

prevent with the changes to the 

eligibility requirements for the 

allowances. Therefore, we are adopting 

the proposed requirement that only 

those nonroad equipment manufacturers 

that install engines and have primary 

responsibility for designing, and 

manufacturing equipment will qualify 

for the allowances or other relief 

provided under the Tier 4 transition 

provisions. However, we are revising 

the provisions regarding which engines 

an equipment manufacturer may 

include in its total count of U.S.-

directed equipment production, which 

in turn affects the number of allowances 

an equipment manufacturer may claim. 

Under today’s action, an equipment