[Federal Register: December 7, 2007 (Volume 72, Number 235)]
[Proposed Rules]
[Page 69521-69552]
[DOCID:fr07de07-21]

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Part IV

Environmental Protection Agency

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40 CFR Parts 9 and 94

Control of Emissions From New Marine Compression-Ignition Engines at or
Above 30 Liters per Cylinder; Proposed Rule

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 9 and 94

[EPA-HQ-OAR-2007-0121; FRL-8502-5]
RIN 2060-AO38

Control of Emissions From New Marine Compression-Ignition Engines
at or Above 30 Liters per Cylinder

AGENCY: Environmental Protection Agency (EPA).

ACTION: Advance notice of proposed rulemaking.

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SUMMARY: EPA is issuing this Advance Notice of Proposed Rulemaking
(ANPRM) to invite comment from all interested parties on our plan to
propose new emission standards and other related provisions for new
compression-ignition marine engines with per cylinder displacement at
or above 30 liters per cylinder. We refer to these engines as Category
3 marine engines. We are considering standards for achieving large
reductions in oxides of nitrogen (NOX) and particulate
matter (PM) through the use of technologies such as in-cylinder
controls, aftertreatment, and low sulfur fuel, starting as early as
2011.
    Category 3 marine engines are important contributors to our
nation's air pollution today and these engines are projected to
continue generating large amounts of NOX, PM, and sulfur
oxides (SOX) that contribute to nonattainment of the
National Ambient Air Quality Standards (NAAQS) for PM2.5 and
ozone across the United States. Ozone and PM2.5 are
associated with serious public health problems including premature
mortality, aggravation of respiratory and cardiovascular disease,
aggravation of existing asthma, acute respiratory symptoms, chronic
bronchitis, and decreased lung function. Category 3 marine engines are
of concern as a source of diesel exhaust, which has been classified by
EPA as a likely human carcinogen. A program such as the one under
consideration would significantly reduce the contribution of Category 3
marine engines to national inventories of NOX, PM, and
SOX, as well as air toxics, and would reduce public exposure
to those pollutants.

DATES: Comments must be received on or before March 6, 2008.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2007-0121, by one of the following methods:
     http://www.regulations.gov: Follow the on-line instructions for

submitting comments.
     E-mail<EMAIL_ADDRESS>     Fax:<PHONE_NUMBER>
     Mail: Environmental Protection Agency, Mail Code: 6102T,
1200 Pennsylvania Ave., NW., Washington, DC, 20460. Please include two
copies.
     Hand Delivery: EPA Docket Center (Air Docket), U.S.
Environmental Protection Agency, EPA West Building, 1301 Constitution
Avenue, NW., Room: 3334 Mail Code: 2822T, Washington, DC. Such
deliveries are only accepted during the Docket's normal hours of
operation, and special arrangements should be made for deliveries of
boxed information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2007-0121. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information provided,

unless the comment includes information claimed to be Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. Do not submit information that you consider to
be CBI or otherwise protected through http://www.regulations.gov or e-mail.

The http://www.regulations.gov Web site is an ``anonymous access'' system,

which means EPA will not know your identity or contact information
unless you provide it in the body of your comment. If you send an e-
mail comment directly to EPA without going through http://www.regulations.gov

your e-mail address will be automatically captured and included as part
of the comment that is placed in the public docket and made available
on the Internet. If you submit an electronic comment, EPA recommends
that you include your name and other contact information in the body of
your comment and with any disk or CD-ROM you submit. If EPA cannot read
your comment due to technical difficulties and cannot contact you for
clarification, EPA may not be able to consider your comment. Electronic
files should avoid the use of special characters, any form of
encryption, and be free of any defects or viruses. For additional
information about EPA's public docket visit the EPA Docket Center
homepage at http://www.epa.gov/epahome/dockets.htm.

    Docket: All documents in the docket are listed in the
http://www.regulations.gov index. Although listed in the index, some

information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in http://www.regulations.gov or in hard copy at the EPA Docket Center, EPA/

DC, EPA West, Room 3334, 1301 Constitution Avenue, 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<PHONE_NUMBER>, and the telephone number for the
Air Docket is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: Michael Samulski, Assessment and
Standards Division, Office of Transportation and Air Quality, 2000
Traverwood Drive, Ann Arbor, MI, 48105; telephone number: (734) 214-
4532; fax number:<PHONE_NUMBER>; e-mail address:
<EMAIL_ADDRESS>

SUPPLEMENTARY INFORMATION:

I. General Information

A. Does This Action Apply to Me?

    This action will affect companies that manufacture, sell, or import
into the United States new marine compression-ignition engines for use
on vessels flagged or registered in the United States; companies and
persons that make vessels that will be flagged or registered in the
United States and that use such engines; and the owners or operators of
such U.S. vessels. Owners and operators of vessels flagged elsewhere
may also be affected, to the extent they use U.S. shipyards or
maintenance and repair facilities; see also Section VII.E regarding
potential application of the standards to foreign vessels that enter
U.S. ports. Finally, this action may also affect companies and persons
that rebuild or maintain these engines. Affected categories and
entities include the following:

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                                                                                Examples of potentially affected
               Category                             NAICS code \a\                          entities
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Industry..............................  333618................................  Manufacturers of new marine
                                                                                diesel engines.
Industry..............................  336611................................  Manufacturers of marine vessels.
Industry..............................  811310................................  Engine repair and maintenance.

Industry..............................  483...................................  Water transportation, freight
                                                                                and passenger.
Industry..............................  324110................................  Petroleum Refineries.
Industry..............................  422710, 422720........................  Petroleum Bulk Stations and
                                                                                Terminals; Petroleum and
                                                                                Petroleum Products Wholesalers.

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\a\ North American Industry Classification System (NAICS).

This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. To determine whether particular activities may be affected by
this action, you should carefully examine the regulations. You may
direct questions regarding the applicability of this action as noted in
FOR FURTHER INFORMATION CONTACT.

B. What Should I Consider as I Prepare My Comments for EPA?

    1. Submitting CBI. Do not submit this information to EPA through
http://www.regulations.gov or e-mail. Clearly mark the part or all of the

information that you claim to be CBI. For CBI information in a disk or
CD-ROM that you mail to EPA, mark the outside of the disk or CD-ROM as
CBI and then identify electronically within the disk or CD-ROM the
specific information that is claimed as CBI. In addition to one
complete version of the comment that includes information claimed as
CBI, a copy of the comment that does not contain the information
claimed as CBI must be submitted for inclusion in the public docket.
Information so marked will not be disclosed except in accordance with
procedures set forth in 40 CFR part 2.
    2. Tips for Preparing Your Comments. When submitting comments,
remember to:
     Identify the rulemaking by docket number and other
identifying information (subject heading, Federal Register date and
page number).
     Follow directions--The agency may ask you to respond to
specific questions or organize comments by referencing a Code of
Federal Regulations (CFR) part or section number.
     Explain why you agree or disagree, suggest alternatives,
and substitute language for your requested changes.
     Describe any assumptions and provide any technical
information and/or data that you used.
     If you estimate potential costs or burdens, explain how
you arrived at your estimate in sufficient detail to allow for it to be
reproduced.
     Provide specific examples to illustrate your concerns, and
suggest alternatives.
     Explain your views as clearly as possible, avoiding the
use of profanity or personal threats.
     Make sure to submit your comments by the comment period
deadline identified.

II. Additional Information About This Rulemaking

    The current emission standards for new compression-ignition marine
engines with per cylinder displacement at or above 30 liters per
cylinder were adopted in 2003 (see 68 FR 9746, February 28, 2003). This
ANPRM relies in part on information that was obtained for that rule,
which can be found in Public Docket EPA-HQ-OAR-2003-0045. This docket
is incorporated into the docket for this action, EPA-HQ-OAR-2007-0121.

Table of Contents

I. Overview
    A. Background: EPA's Current Category 3 Standards
    B. Program Under Consideration
II. Why Is EPA Considering New Controls?
    A. Ozone and PM Attainment
    B. Public Health Impacts
    1. Particulate Matter
    2. Ozone
    3. Air Toxics
    C. Other Environmental Effects
    1. Visibility
    2. Plant and Ecosystem Effects of Ozone
    3. Acid Deposition
    4. Eutrophication and Nitrification
    5. Materials Damage and Soiling
III. Relevant Clean Air Act Provisions
IV. International Regulation of Air Pollution From Ships
V. Potential Standards and Effective Dates
    A. NOX Standards
    B. PM and SOX Standards
VI. Emission Control Technology
    A. Engine-Based NOX Control
    1. Traditional In-Cylinder Controls
    2. Water-Based Technologies
    3. Exhaust Gas Recirculation
    B. NOX Aftertreatment
    C. PM and SOX Control
    1. In-Cylinder Controls
    2. Fuel Quality
    3. Exhaust Gas Scrubbers
VII. Certification and Compliance
    A. Testing
    1. PM Sampling
    2. Low Power Operation
    3. Test Fuel
    B. On-off Technologies
    C. Parameter Adjustment
    D. Certification of Existing Engines
    E. Other Compliance Issues
    1. Engines on Foreign-Flagged Vessels
    2. Non-Diesel Engines
VIII. Potential Regulatory Impacts
    A. Emission Inventory
    1. Estimated Inventory Contribution
    2. Inventory Calculation Methodology
    B. Potential Costs
IX. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    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
    H. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
    I. National Technology Transfer Advancement Act
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations

I. Overview

    In recent years, EPA has adopted major new programs designed to
reduce emissions from diesel engines. When fully phased in, these new
programs for highway \1\ and land-based nonroad \2\ diesel engines will
lead to the elimination of over 90 percent of harmful regulated
pollutants from these sources. The public health and welfare benefits
of these actions are very significant, projected at over $70 billion
and $83 billion for our highway and land-based nonroad diesel programs,
respectively. In contrast, the corresponding cost of these programs
will be a small fraction of this amount. We have estimated the annual
cost at $4.2 billion and $2 billion, respectively in 2030. These
programs are being implemented over the next decade.
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    \1\ 66 FR 5001, January 18, 2001.
    \2\ 69 FR 38957, June 29, 2004.
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    We have also recently proposed a new emission control program for
locomotives and marine diesel engines.\3\ The proposed standards would
address all types of diesel locomotives (line-haul, switch, and
passenger rail) and all types of marine diesel engines below 30 liters
per cylinder displacement (including propulsion engines used on vessels
from recreational and small fishing boats to super-yachts, tugs and
Great Lakes freighters, and auxiliary engines ranging from small
generator sets to large generators on ocean-going

vessels).\4\ The proposal consists of a three-part program. First, we
are proposing more stringent standards for existing locomotives that
would apply when they are remanufactured; we are also requesting
comment on a program that would apply a similar requirement to existing
marine diesel engines up to 30 liters per cylinder displacement when
they are remanufactured. Second, we are proposing a set of near-term
emission standards, referred to as Tier 3, for newly-built locomotives
and marine engines up to 30 liters per cylinder displacement that
reflect the application of in-cylinder technologies to reduce engine-
out NOX and PM. Third, we are proposing longer-term
standards for locomotive engines and certain marine diesel engines,
referred to as Tier 4 standards, that reflect the application of high-
efficiency catalytic aftertreatment technology enabled by the
availability of ultra-low sulfur diesel (ULSD) fuel.
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    \3\ 72 FR 15937, April 3, 2007.
    \4\ Marine diesel engines at or above 30 l/cyl displacement are
not included in this program.
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    Marine diesel engines above 30 liters per cylinder, called Category
3 marine diesel engines, are significant contributors to our national
mobile source emission inventory. Category 3 marine engines are
predominantly used in ocean-going vessels (OGV). The contribution of
these engines to national inventories is described in section VIII.A of
this preamble. These inventories are expected to grow significantly due
to expected increases in foreign trade. Without new controls, we
anticipate that their overall contribution to mobile source oxides of
nitrogen (NOX) and fine diesel particulate matter
(PM2.5) emissions will increase to about 34 and 45 percent
respectively by 2030. Their contribution to emissions in port areas on
a percentage basis would be expected to be significantly higher.
    Reducing emissions from these engines can lead to improvements in
public health and would help states and localities attain and maintain
the PM and ozone national ambient air quality standards. Both ozone and
PM2.5 are associated with serious public health problems,
including premature mortality, aggravation of respiratory and
cardiovascular disease (as indicated by increased hospital admissions
and emergency room visits, school absences, lost work days, and
restricted activity days), changes in lung function and increased
respiratory symptoms, altered respiratory defense mechanisms, and
chronic bronchitis. In addition, diesel exhaust is of special public
health concern. Since 2002 EPA has classified diesel exhaust as likely
to be carcinogenic to humans by inhalation at environmental
exposures.\5\ Recent studies are showing that populations living near
large diesel emission sources such as major roadways,\6\ rail yards,
and marine ports \7\ are likely to experience greater diesel exhaust
exposure levels than the overall U.S. population, putting them at
greater health risks. We are currently studying the size of the U.S.
population living near a sample of approximately 50 marine ports and
will place this information in the docket for this ANPRM upon
completion.
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    \5\ 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.
 This document is

available in Docket EPA-HQ-OAR-2007-0121.
    \6\ Kinnee, E.J.; Touman, J.S.; Mason, R.; Thurman, J.; Beidler,
A.; Bailey, C.; Cook, R. (2004) Allocation of onroad mobile
emissions to road segments for air toxics modeling in an urban area.
Transport. Res. Part D 9: 139-150.
    \7\ State of California Air Resources Board. Roseville Rail Yard
Study. Stationary Source Division, October 14, 2004. This document
is available electronically at: http://www.arb.ca.gov/diesel/documents/rrstudy.htm
 and State of California Air Resources Board.

Diesel Particulate Matter Exposure Assessment Study for the Ports of
Los Angeles and Long Beach, April 2006. This document is available
electronically at: http://www.arb.ca.gov/regact/marine2005/portstudy0406.pdf.
 This document is available in Docket EPA-HQ-OAR-

2007-0121.
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    Category 3 marine engines are currently subject to emission
standards that rely on engine-based technologies to reduce emissions.
These standards, which were adopted in 2003 and went into effect in
2004, are equivalent to the NOX limits in Annex VI to the
MARPOL Convention, adopted by a Conference of the Parties to the
Convention in 1997. The opportunity to gain large additional public
health benefits through the application of advanced emission control
technologies, including aftertreatment, lead us to consider more
stringent standards for these engines. In order to achieve these
emission reductions on the ship, however, it may be necessary to
control the sulfur content of the fuel used in these engines. Finally,
because of the international nature of ocean-going marine
transportation, and the very large inventory contribution from foreign-
flagged vessels, we may also consider the applicability of federal
standards to foreign vessels that enter U.S. ports (see Section VII.E).
    In this ANPRM, we describe the emission program we are considering
for Category 3 marine diesel engines and technologies we believe can be
used to achieve those standards. The remainder of this section provides
background on our current emission control program and gives an
overview of the program we are considering. Section II provides a brief
discussion of the health and human impacts of emissions from Category 3
marine diesel engines. Section III identifies relevant Clean Air Act
provisions and Section IV summarizes our interactions with the
International Maritime Organization (IMO). In Sections V and VI, we
describe the potential emission limits and the emission control
technologies that can be used to meet them. Section VII discusses
several compliance issues. In Section VIII, we summarize the
contribution of these engines to current mobile source NOX
and PM inventories in the United States and describe our plans for our
future cost analysis. Finally, Section IX contains information on
statutory and executive order reviews covering this action. We are
interested in comments covering all aspects of this ANPRM.

A. Background: EPA's Current Category 3 Standards

    EPA currently has emission standards for Category 3 marine diesel
engines. The standards, adopted in 2003, are equivalent to the MARPOL
Annex VI NOX limits. They apply to any Category 3 engine
installed on a vessel flagged or registered in the United States,
beginning in 2004.
    In our 2003 final rule, we considered adopting standards that would
achieve greater emission reductions through expanding the use and
optimization of in-cylinder controls as well as through the use of
advanced emission control technologies including water technologies
(water injection, emulsification, humidification) and selective
catalytic reduction (SCR). However, we determined that it was
appropriate to defer a final decision on the longer-term Tier 2
standards to a future rulemaking. While there was a certain amount of
information available at the time about the advanced technologies,
there were several outstanding technical issues concerning the
widespread commercial use of those technologies. Deferring the Tier 2
standards to a second rulemaking allowed us the opportunity to obtain
important additional information on the use of these advanced
technologies that we expected to become available over the next few
years. This new information was expected to include: (1) New
developments as manufacturers continue to make various improvements to
the technology and address any remaining concerns, (2) data or
experience from recently initiated in-use installations using the
advanced technologies, and (3) information from

longer-term in-use experience with the advanced technologies that would
be helpful for evaluating the long-term durability of emission
controls. An additional reason to defer the adoption of long-term
standards for Category 3 engines was to allow the United States to
pursue further negotiations in the international arena to achieve more
stringent global emission standards for marine diesel engines.\8\
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    \8\ 68 FR 9748, February 28, 2003.
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    Finally, because the standards adopted in our 2003 rulemaking were
equivalent to the international standards, we determined that it was
appropriate to defer a decision on the application of federal standards
to engines on foreign-flagged vessels that enter U.S. ports. We
indicated that we would consider this issue again in our future
rulemaking, and we intend to evaluate how best to address emissions
from foreign vessels in this action. We expect our proposal to reflect
an approach similar to the emission program recently proposed by the
United States in the current discussions at the IMO to amend the MARPOL
Annex VI standards to a level that achieves significant reductions in
NOX, PM, and SOX emissions from Category 3 marine
diesel engines.\9\ We will evaluate progress at the IMO and, as
appropriate, consider the application of new EPA national standards to
engines on foreign-flagged vessels that enter U.S. ports under our
Clean Air Act authority.
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    \9\ ``Revision of the MARPOL Annex VI, the NOX
Technical Code and Related Guidelines; Development of Standards for
NOX, PM, and SOX,'' submitted by the United
States, BLG 11/5, Sub-Committee on Bulk Liquids and Gases, 11th
Session, Agenda Item 5, February 9, 2007, Docket ID EPA-HQ-OAR-2007-
0121-0034. This document is also available on our Web site: http://

http://www.epa.gov/otaq/oceanvessels.com.

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B. Program Under Consideration

    As described in Section VI, continuing advancements in diesel
engine control technology support the adoption of long-term technology-
forcing standards for Category 3 engines. With regard to NOX
control, SCR has been applied to many land-based applications, and the
technology continues to be refined and improved. More propulsion
engines have been fitted with the technology, especially on vessels
operating in the Baltic Sea, and it is being found to be very effective
and durable in-use. These improvements, in addition to better
optimization of engine-based controls, have the potential for
significant NOX reductions. PM and SOX emissions
from Category 3 engines are primarily due to the sulfur content of the
fuel they use. In the short term, these emissions can be decreased by
using fuel with a reduced sulfur content or through the use of exhaust
gas cleaning technology; this is the idea behind the SOX
Emission Control Areas (SECAs) provided for in Annex VI. More
significant reductions can be obtained by using distillate fuel, and at
least one company has been voluntarily switching from residual fuel to
distillate fuel while their ships are operating within 24 nautical
miles of certain California ports.\10\ Their experience demonstrates
that this type of fuel switching can be done safely and efficiently,
although the higher price of distillate fuel may limit this approach to
near-coast and port areas. In addition, emission scrubbing techniques
are improving, which have the potential for significant PM reductions
from Category 3 engines.
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    \10\ See ``Maersk Line Announces Fuel Switch for Vessels Calling
California'' at http://www.maerskline.com/globalfile/?path=/pdf/environment_fuel_initiative
.

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    We are currently considering an emission control program for new
Category 3 marine diesel engines that takes advantage of these new
emission reduction approaches. The program we are considering,
described in more detail in Section V, would focus on NOX,
PM, and SOX control from new and existing engines. This
program is similar to the one recently proposed at the IMO by the U.S.
government.
    For NOX control for new engines, we are considering a
two-phase approach. In the first phase, called Tier 2, we are
considering a NOX emission limit for new engines that would
be 15 to 25 percent below the current NOX limits as defined
by the NOX curve in the current Tier 1 standards. These
standards would apply at all times. In the second phase, called Tier 3,
we are considering a NOX emission limit that would achieve
an additional 80 percent reduction from the Tier 2 limits. We are
considering the Tier 2 limits as early as 2011 and Tier 3 limits in the
2016 time frame. Because Tier 3 standards are likely to be achieved
using aftertreatment technologies, the application of the standards
could be geographically-based thereby allowing operators to turn the
system off while they are outside of a specified geographic area. That
area could be the same as the compliance area for PM and SOX
reductions (see below). This two-part approach would permit near-term
emission reductions while achieving deeper reductions through long-term
standards.
    We believe a two-phase approach under consideration is an effective
way to maximize NOX emission reductions from these engines.
While we continue to believe that the focus of the emission control
program should be on meaningful long-term standards that would apply
high-efficiency catalytic aftertreatment to these engines, short-term
emission reductions could be achieved through incremental improvements
to existing engine designs. These design improvements can be consistent
with a long-term, after treatment-based Tier 3 program. The recent
experience of engine manufacturers in applying advanced control
technologies to other mobile sources suggests that incremental changes
of the type that would be used to achieve the Tier 2 standards may also
be used in strategies to achieve the Tier 3 standards. For example,
Tier 2 technologies may allow engine manufacturers to size their
aftertreatment control systems smaller. A more stringent Tier 2 control
program, however, may risk diverting resources away from Tier 3 and may
result in the application of emission reduction strategies that are not
consistent with high-efficiency catalytic aftertreatment-based
controls.
    For PM and SOX control, we are considering a performance
standard that would reflect the use of low-sulfur distillate fuels or
the use of exhaust gas cleaning technology (e.g., scrubbers), or a
combination of both. These standards would apply as early as 2011 and
would potentially achieve SOX reductions as high as 95
percent and substantial PM reductions as well. We believe a performance
standard would be a cost-effective approach for PM emission reductions
since it allows ship owners to choose from a variety of mechanisms to
achieve the standard, including fuel switching or the use of emission
scrubbers. Compliance with the PM and SOX emissions could be
limited to operation in a defined geographical area. For example, ships
operating in the defined coastal areas (i.e., within a specified
distance from shore) would be required to meet the requirements while
operating within the area, but could ``turn off'' the control mechanism
while on the open sea. This type of performance standard could apply to
all vessels, new or existing, that operate within the designated area.
An important advantage of a geographic approach for PM and
SOX control, as well as the Tier 3 standards, is that it
would result in emission reductions that are important for health and
human welfare while reducing the costs of the program since ships will
not be required to comply with the limits while they are operating
across large areas of the open sea.

    We are also considering NOX emission controls for
existing Category 3 engines that would begin in 2012. There are at
least two approaches that could be used for setting NOX
emission limits for existing engines. The first would be to set a
performance standard, for example a reduction of about 20 percent from
the Tier 1 NOX limits; how this reduction is achieved would
be left up to the ship owner. Alternatively, the second approach would
be to express the requirement as a specified action, for example an
injector change known to achieve a particular reduction; this approach
would simplify verification, but the emission reduction results may
vary across engines. We will be exploring both of these alternative
approaches and seek comment on the relative merits of each.

II. Why Is EPA Considering New Controls?

    Category 3 marine engines subject to today's ANPRM generate
significant emissions of fine particulate matter (PM2.5),
nitrogen oxides (NOX) and sulfur oxides (SOX)
that contribute to nonattainment of the National Ambient Air Quality
Standards for PM2.5 and ozone. NOX is a key
precursor to ozone and secondary PM formation while SOX is a
significant contributor to ambient PM2.5. These engines also
emit volatile organic compounds (VOCs), carbon monoxide (CO), and
hazardous air pollutants or air toxics, which are associated with
adverse health effects. Diesel exhaust is of special public health
concern, and since 2002 EPA has classified it as likely to be
carcinogenic to humans by inhalation at environmental exposures. In
addition, emissions from these engines also cause harm to public
welfare, contributing to visibility impairment, and other detrimental
environmental impacts across the U.S.

A. Ozone and PM Attainment

    Many of our nation's most serious ozone and PM2.5
nonattainment areas are located along our coastlines where vessels
using Category 3 marine engine emissions contribute to air pollution in
or near urban areas where significant numbers of people are exposed to
these emissions. The contribution of these engines to air pollution is
substantial and is expected to grow in the future. Currently more than
40 major U.S. ports \11\ along our Atlantic, Great Lakes, Gulf of
Mexico, and Pacific coast lines are located in nonattainment areas for
ozone and/or PM2.5 (See Figure II-1).
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    \11\ American Association of Port Authorities (AAPA), Industry
Statistics, 2005 port rankings by cargo tonnage.
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    The health and environmental effects associated with these
emissions are a classic example of a negative externality (an activity
that imposes uncompensated costs on others). With a negative
externality, an activity's social cost (the cost borne by society
imposed as a result of the activity taking place) exceeds its private
cost (the cost to those directly engaged in the activity). In this
case, emissions from Category 3 marine engines impose public health and
environmental costs on society. However, these added costs to society
are not reflected in the costs of those using these engines and
equipment. The market system itself cannot correct this negative
externality because firms in the market are rewarded for minimizing
their operating costs, including the costs of pollution control. In
addition, firms that may take steps to use equipment that reduces air
pollution may find themselves at a competitive economic disadvantage
compared to firms that do not. The emission standards that EPA is
considering for Category 3 marine diesel engines would help address
this market failure and reduce the negative externality from these
emissions by providing a positive incentive for engine manufacturers to
produce engines that emit fewer harmful pollutants and for vessel
builders and owners to use those cleaner engines.
    When considering vessel operations in the United States' Exclusive
Economic Zone (EEZ), emissions from Category 3 marine engines account
for a substantial portion of the United States' ambient
PM2.5 and NOX mobile source emissions.\12\ We
estimate that annual emissions in 2007 from these engines totaled more
than 870,000 tons of NOX emissions and 66,000 tons of
PM2.5. This represents more than 8 percent of U.S. mobile
source NOX and 15 percent of U.S. mobile source
PM2.5 emissions. These numbers are projected to increase
significantly through 2030 due to growth in the use of Category 3
marine engines to transport overseas goods to U.S. markets and U.S.
produced goods overseas. Furthermore, their proportion of the emission
inventory is projected to increase significantly as regulatory controls
on other major emission categories take effect. By 2030, NOX
emissions from these ships are projected to more than double, growing
to 2.1 million tons a year or 34 percent of U.S. mobile source
NOX emissions while PM2.5 emissions are expected
to almost triple to 170,000 tons annually comprising 45 percent of U.S.
mobile source PM2.5 emissions.\13\ In 2007 annual emission
of SOX from Category 3 engines totaled almost 530,000 tons
or more than half of mobile source SOX and by 2030 these
emissions are expected to increase to 1.3 million tons or 94 percent of
mobile source emissions.
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    \12\ In general, the United States Exclusive Economic Zone (EEZ)
extends to 200 nautical miles from the U.S. coast. Exceptions
include geographic regions near Canada, Mexico and the Bahamas where
the EEZ extends less than 200 nautical miles from the U.S. coast.
See map in Figure VIII-1, below.
    \13\ These projections are based on growth rates ranging from
1.7 to 5.0 percent per year, depending on the geographic region. The
growth rates are described in Section VIII.A.
---------------------------------------------------------------------------

    Both ozone and PM2.5 are associated with serious public
health problems, including premature mortality, aggravation of
respiratory and cardiovascular disease (as indicated by increased
hospital admissions and emergency room visits, school absences, lost
work days, and restricted activity days), increased respiratory
symptoms, altered respiratory defense mechanisms, and chronic
bronchitis. Diesel exhaust is of special public health concern, and
since 2002 EPA has classified it as likely to be carcinogenic to humans
by inhalation at environmental exposures.\14\
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    \14\ 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.
 This document is available in Docket

EPA-HQ-OAR-2007-0121.
---------------------------------------------------------------------------

    Recent studies are showing that populations living near large
diesel emission sources such as major roadways \15\, railyards, and
marine ports \16\ are likely to experience greater diesel exhaust
exposure levels than the overall U.S. population, putting them at
greater health risks. As part of our current locomotive and marine
diesel engine rulemaking (72 FR 15938, April 3, 2007), we are studying
the U.S. population living near a sample of 47 marine ports which are
located along the entire east and west coasts of the U.S. as well as
the Gulf of Mexico and the Great Lakes region. This information

will be placed in the docket for this rulemaking when the study is
completed. The PM2.5 and NOX reductions which
would occur as a result of applying advanced emissions control
strategies to Category 3 marine engines could both reduce the amount of
emissions that populations near these sources are exposed to and assist
state and local governments as they work to reduce NOX and
PM2.5 inventories.
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    \15\ Kinnee, E.J.; Touman, J.S.; Mason, R.; Thurman,J.; Beidler,
A.; Bailey, C.; Cook, R. (2004) Allocation of onroad mobile
emissions to road segments for air toxics modeling in an urban area.
Transport. Res. Part D 9: 139-150.
    \16\ State of California Air Resources Board. Roseville Rail
Yard Study. Stationary Source Division, October 14, 2004. This
document is available electronically at: http://www.arb.ca.gov/diesel/documents/rrstudy.htm
 and State of California Air Resources

Board. Diesel Particulate Matter Exposure Assessment Study for the
Ports of Los Angeles and Long Beach, April 2006. This document is
available electronically at: http://www.arb.ca.gov/regact/marine2005/portstudy0406.pdf.
 These documents are available in

Docket EPA-HQ-OAR-2007-0121.
---------------------------------------------------------------------------

    Today millions of Americans continue to live in areas that do not
meet existing air quality standards. As of June 2007 there are
approximately 88 million people living in 39 designated areas (which
include all or part of 208 counties) that either do not meet the
current PM2.5 NAAQS or contribute to violations in other
counties, and 149 million people living in 94 areas (which include all
or part of 391 counties) designated as not in attainment for the 8-hour
ozone NAAQS. These numbers do not include the people living in areas
where there is a significant future risk of failing to maintain or
achieve either the PM2.5 or ozone NAAQS.
    Figure II-1 illustrates the widespread nature of these problems and
depicts counties which are currently (as of March 2007) designated
nonattainment for either or both the 8-hour ozone NAAQS and
PM2.5 NAAQS. It also shows the location of mandatory class I
federal areas for visibility. Superimposed on this map are top U.S.
ports many of which receive significant port stops from ocean going
vessels operating with Category 3 marine engines. Currently more than
40 major U.S. deep sea ports are located in these nonattainment areas.
Many ports are located in areas rated as class I federal areas for
visibility impairment and regional haze. It should be noted that
emissions from ocean-going vessels are not simply a localized problem
related only to cities that have commercial ports. Virtually all U.S.
coastal areas are affected by emissions from ships that transit between
those ports, using shipping lanes that are close to land. Many of these
coastal areas also have high population densities. For example, Santa
Barbara, which has no commercial port, estimates that engines on ocean-
going marine vessels currently contribute about 37 percent of total
NOX in their area.\17\ These emissions are from ships that
transit the area, and ``are comparable to (even slightly larger than)
the amount of NOX produced onshore by cars and truck.'' By
2015 these emissions are expected to increase 67 percent, contributing
61 percent of Santa Barbara's total NOX emissions. This mix
of emission sources led Santa Barbara to point out that they will be
unable to meet air quality standards for ozone without significant
emission reductions from these vessels, even if they completely
eliminate all other sources of pollution. Interport emissions from OGV
also contribute to other environmental problems, affecting sensitive
marine and land ecosystems. As discussed above, EPA recently completed
estimates of the contribution of Category 3 engines to emission
inventories. We recognize that air quality effects may vary from one
port/coastal area to another with differences in meteorology, because
of spatial differences in emissions with ship movements within regional
areas. In addition, these emissions may also affect adjacent coastal
areas. For these reasons, we plan to study several different port areas
to better assess the air quality effects of emissions from Category 3
engines. We believe that there are additional port and adjacent coastal
areas affected by emissions from Category 3 marine engines. We will be
performing air quality modeling specific to this issue to better assess
these impacts.

    \17\ Memorandum to Docket A-2001-11 from Jean-Marie Revelt,
Santa Barbara County Air Quality News, Issue 62, July-August 2001
and other materials provided to EPA by Santa Barbara County,'' March
14, 2002.
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BILLING CODE 6560-50-P

[GRAPHIC] [TIFF OMITTED] TP07DE07.024

BILLING CODE 6560-50-C

    Emissions from Category 3 marine engines account for a substantial
and growing portion of the U.S.'s coastal ambient PM2.5 and
NOX levels. The emission reductions from tightened Category
3 marine engine standards could play an important part in states'
efforts to attain and maintain the NAAQS in the coming decades,
especially in coastal nonattainment areas, where these engines comprise
a large portion of the remaining NOX and PM2.5
emissions inventories. For example, 2001 emission inventories for
California's South Coast ozone and PM nonattainment areas \18\ indicate
that ocean-going vessels (OGVs) contribute about 30 tons per day (tpd)
of NOX and 2\1/2\ tpd of PM2.5 to regional
inventories--and absent additional emission controls, this number would
almost triple in 2020 to 86 tpd of NOX and 8 tpd of
PM2.5 as port-related activities continue to grow. The
Houston-Galveston-Beaumont area is also faced with growing OGV
inventories which continue to hamper their area's effort to achieve and
maintain clean air. Today, OGVs in the Houston nonattainment area
annually contribute about 27 tpd of NOX emissions and this
is projected to climb to 30 tpd by 2009.\19\ In the Corpus Christi
area, OGVs in 2001 were responsible for about 16 tpd of
NOX.\20\ Finally, in the New York/Northern New Jersey
nonattainment area, 2000 inventories \21\ indicated that OGVs
contributed 12 tpd of NOX emissions and about 0.75 tpd of
PM2.5 emissions to PM inventories. We request comment on the
impact Category 3 marine engines have on state and local emission
inventories as well as their efforts to meet the ozone and
PM2.5 NAAQS.
---------------------------------------------------------------------------

    \18\ California Air Resources Board (2006). Emission Reduction
Plan for Ports and Goods Movements, (April 2006) Appendix B-3,
Available electronically at http://www.arb.ca.gov/gmp/docs/finalgmpplan090905.pdf
.

    \19\ Texas Commission On Environmental Quality (2006) Houston-
Galveston-Brazoria 8-Hour Ozone State Implemental Plan & Rules,
Informational Meeting Presentation, Kelly Keel, Air Quality Planning
Section.
    \20\ Air Consulting and Engineering Solutions, Final Report
Phase II Corpus Christi Regional Airshed, (August 2001) Project
Number 21-01-0006.
    \21\ The Port Authority of New York & New Jersey, (2003), The
New York, Northern New Jersey, Long Island Nonattainment Area
Commercial Marine Vessel Emissions Inventory, Prepared by Starcrest
Consulting Group, LLC.
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    Recently, new studies \22\ from the State of California provide
evidence that PM2.5 emissions within marine ports contribute
significantly to elevated ambient concentrations near these sources. A
substantial number of people experience exposure to Category 3 marine
engine emissions, raising potential health concerns. Additional
information on marine port emissions and ambient exposures can be found
in section II.B.3 of this ANPRM.
---------------------------------------------------------------------------

    \22\ State of California Air Resources Board. Roseville Rail
Yard Study. Stationary Source Division, October 14, 2004. This
document is available electronically at: http://www.arb.ca.gov/diesel/documents/rrstudy.htm
 and State of California Air Resources

Board. Diesel Particulate Matter Exposure Assessment Study for the
Ports of Los Angeles and Long Beach, April 2006. This document is
available electronically at: ftp://ftp.arb.ca.gov/carbis/msprog/offroad/marinevess/documents/portstudy0406.pdf.
 These documents are

available in Docket EPA-HQ-OAR-2007-0121.
---------------------------------------------------------------------------

    In addition to public health impacts, there are serious public
welfare and environmental impacts associated with ozone and
PM2.5. Specifically, ozone causes damage to vegetation which
leads to crop and forestry economic losses, as well as harm to national
parks, wilderness areas, and other natural systems. NOX,
SOX and PM2.5 can contribute to the substantial
impairment of visibility in many parts of the U.S., where people live,
work, and recreate, including national parks, wilderness areas, and
mandatory class I federal areas. The deposition of airborne particles
can also reduce the aesthetic appeal of buildings and culturally
important articles through soiling, and can contribute directly (or in
conjunction with other pollutants) to structural damage by means of
corrosion or erosion. Finally, NOX and SOX
emissions from diesel engines contribute to the acidification,
nitrification, and eutrophication of water bodies.
    While EPA has already adopted many emission control programs that
are expected to reduce ambient ozone and PM2.5 levels,
including the Clean Air Interstate Rule (CAIR) (70 FR 25162, May 12,
2005), the Clean Air Nonroad Diesel Rule (69 FR 38957, June 29, 2004),
the Heavy Duty Engine and Vehicle Standards and Highway Diesel Fuel
Sulfur Control Requirements (66 FR 5002, Jan. 18, 2001), and the Tier 2
Vehicle and Gasoline Sulfur Program (65 FR 6698, Feb. 10, 2000), the
PM2.5 and NOX emission reductions resulting from
tightened standards for Category 3 marine diesel engines would greatly
assist nonattainment areas, especially along our nation's coasts, in
attaining and maintaining the ozone and the PM2.5 NAAQS in
the near term and in the decades to come.
    In September 2006, EPA finalized revised PM2.5 NAAQS.
Nonattainment areas will be designated with respect to the revised
PM2.5 NAAQS in early 2010. EPA modeling, conducted as part
of finalizing the revised NAAQS, projects that in 2015 up to 52
counties with 53 million people may violate the daily, annual, or both
standards for PM2.5 while an additional 27 million people in
54 counties may live in areas that have air quality measurements within
10 percent of the revised NAAQS. Even in 2020 up to 48 counties, with
54 million people, may still not be able to meet the revised
PM2.5 NAAQS and an additional 25 million people, living in
50 counties, are projected to have air quality measurements within 10
percent of the revised standards. The PM2.5 inventory
reductions that would be achieved from applying advanced emissions
control strategies to Category 3 engines could be useful in helping
coastal nonattainment areas, to both attain and maintain the revised
PM2.5 NAAQS.
    State and local governments are working to protect the health of
their citizens and comply with requirements of the Clean Air Act (CAA
or ``the Act''). As part of this effort they recognize the need to
secure additional major reductions in both PM2.5 and
NOX emissions by undertaking state level action.\23\
However, they also seek further Agency action for national standards,
including the setting of stringent new Category 3 marine engine
standards since states are preempted from setting new engine emissions
standards for this class of engines.\24\
---------------------------------------------------------------------------

    \23\ For example, see: California Air Resources Board (2006).
Emission Reduction Plan for Ports and Goods Movements, (April 2006),
Available electronically at http://www.arb.ca.gov/gmp/docs/finalgmpplan090905.pdf
.

    \24\ For example, see letter dated November 29, 2006 from
California Environmental Protection Agency to Administrator Stephen
L. Johnson and January 20, 2006 letter from Executive Director,
Puget Sound Clean Air Agency to Administrator Stephen L. Johnson.
---------------------------------------------------------------------------

B. Public Health Impacts

1. Particulate Matter
    The emission control program for Category 3 marine engines has the
potential to significantly reduce their contribution to
PM2.5 inventories. In addition, these engines emit high
levels of NOX which react in the atmosphere to form
secondary PM2.5, ammonium nitrate. Category 3 marine engines
also emit large amounts of SO2 and HC which react in the
atmosphere to form secondary PM2.5 composed of sulfates and
organic carbonaceous PM2.5. The emission control program
being considered would reduce the contribution of Category 3 engines to
both directly emitted diesel PM and secondary PM emissions.

(a) Background
    Particulate matter (PM) represents a broad class of chemically and
physically diverse substances. It can be principally characterized as
discrete particles that exist in the condensed (liquid or solid) phase
spanning several orders of magnitude in size. PM is further described
by breaking it down into size fractions. PM10 refers to
particles generally less than or equal to 10 micrometers ([mu]m).
PM2.5 refers to fine particles, those particles generally
less than or equal to 2.5 [mu]m in diameter. Inhalable (or
``thoracic'') coarse particles refer to those particles generally
greater than 2.5 [mu]m but less than or equal to 10 [mu]m in diameter.
Ultrafine PM refers to particles less than 100 nanometers (0.1 [mu]m).
Larger particles tend to be removed by the respiratory clearance
mechanisms (e.g. coughing), whereas smaller particles are deposited
deeper in the lungs.
    Fine particles are produced primarily by combustion processes and
by transformations of gaseous emissions (e.g., SOX,
NOX and VOCs) in the atmosphere. The chemical and physical
properties of PM2.5 may vary greatly with time, region,
meteorology, and source category. Thus, PM2.5, may include a
complex mixture of different pollutants including sulfates, nitrates,
organic compounds, elemental carbon and metal compounds. These
particles can remain in the atmosphere for days to weeks and travel
through the atmosphere hundreds to thousands of kilometers.
    The primary PM2.5 NAAQS includes a short-term (24-hour)
and a long-term (annual) standard. The 1997 PM2.5 NAAQS
established by EPA set the 24-hour standard at a level of 65[mu]g/
m3 based on the 98th percentile concentration averaged over
three years. (This air quality statistic compared to the standard is
referred to as the ``design value.'') The annual standard specifies an
expected annual arithmetic mean not to exceed 15[mu]g/m3
averaged over three years. EPA has recently finalized PM2.5
nonattainment designations for the 1997 standard (70 FR 943, Jan 5,
2005).\25\ All areas currently in nonattainment for PM2.5
will be required to meet these 1997 standards between 2009 and 2014.
---------------------------------------------------------------------------

    \25\ U.S. EPA, Air Quality Designations and Classifications for
the Fine Particles (PM2.5) National Ambient Air Quality
Standards, December 17, 2004. (70 FR 943, Jan 5, 2005) This document
is available in Docket EPA-HQ-OAR-2007-0121. This document is also
available on the Web at: http://www.epa.gov/pmdesignations/.

---------------------------------------------------------------------------

    EPA has recently amended the NAAQS for PM2.5 (71 FR
61144, October 17, 2006). The final rule, signed on September 21, 2006
and published in the Federal Register on October 17, 2006, addressed
revisions to the primary and secondary NAAQS for PM to provide
increased protection of public health and welfare, respectively. The
level of the 24-hour PM2.5 NAAQS was revised from 65[mu]g/
m3 to 35[mu]g/m3 to provide increased protection
against health effects associated with short-term exposures to fine
particles. The current form of the 24-hour PM2.5 standard
was retained (e.g., based on the 98th percentile concentration averaged
over three years). The level of the annual PM2.5 NAAQS was
retained at 15[mu]g/m3, continuing protection against health
effects associated with long-term exposures. The current form of the
annual PM2.5 standard was retained as an annual arithmetic
mean averaged over three years, however, the following two aspects of
the spatial averaging criteria were narrowed: (1) The annual mean
concentration at each site shall be within 10 percent of the spatially
averaged annual mean, and (2) the daily values for each monitoring site
pair shall yield a correlation coefficient of at least 0.9 for each
calendar quarter.
    With regard to the secondary PM2.5 standards, EPA has
revised these standards to be identical in all respects to the revised
primary standards. Specifically, EPA has revised the current 24-hour
PM2.5 secondary standard by making it identical to the
revised 24-hour PM2.5 primary standard and retained the
annual PM2.5 secondary standard. This suite of secondary
PM2.5 standards is intended to provide protection against
PM-related public welfare effects, including visibility impairment,
effects on vegetation and ecosystems, and material damage and soiling.
    The 2006 standards became effective on December 18, 2006. As a
result of the 2006 PM2.5 standard, EPA will designate new
nonattainment areas in early 2010. The timeframe for areas attaining
the 2006 PM NAAQS will likely extend from 2015 to 2020.
(b) Health Effects of PM2.5
    Scientific studies show ambient PM is associated with a series of
adverse health effects. These health effects are discussed in detail in
the 2004 EPA Particulate Matter Air Quality Criteria Document (PM
AQCD), and the 2005 PM Staff Paper.26 27 28
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    \26\ U.S. EPA (1996) Air Quality Criteria for Particulate
Matter, EPA 600-P-95-001aF, EPA 600-P-95-001bF. This document is
available in Docket EPA-HQ-OAR-2007-0121.
    \27\ U.S. EPA (2004) Air Quality Criteria for Particulate Matter
(Oct 2004), Volume I Document No. EPA600/P-99/002aF and Volume II
Document No. EPA600/P-99/002bF. This document is available in Docket
EPA-HQ-OAR-2007-0121.
    \28\ U.S. EPA (2005) Review of the National Ambient Air Quality
Standard for Particulate Matter: Policy Assessment of Scientific and
Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This
document is available in Docket EPA-HQ-OAR-2007-0121.
---------------------------------------------------------------------------

    Health effects associated with short-term exposures (hours to days)
to ambient PM include premature mortality, increased hospital
admissions, heart and lung diseases, increased cough, adverse lower-
respiratory symptoms, decrements in lung function and changes in heart
rate rhythm and other cardiac effects. 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, show associations between long-term exposure to ambient
PM2.5 and both total and cardiovascular and respiratory
mortality.\29\ In addition, a reanalysis of the American Cancer Society
Study shows an association between fine particle and sulfate
concentrations and lung cancer mortality.\30\ The Category 3 marine
engines covered in this proposal contribute to both acute and chronic
PM2.5 exposures.
---------------------------------------------------------------------------

    \29\ 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.
    \30\ Pope Ca, III; Thun, MJ; Namboodiri, MM; Docery, DW; Evans,
JS; Speizer, FE; Heath, CW. 1995. Particulate air pollution as a
predictor of mortality in a prospective study of U.S. adults. Am J
Respir Crit Care Med 151:669-674.
---------------------------------------------------------------------------

    The health effects of PM2.5 have been further documented
in local impact studies which have focused on health effects due to
PM2.5 exposures measured on or near roadways.\31\ Taking
account of all air pollution sources, including both spark-ignition
(gasoline) and diesel powered vehicles, these latter studies indicate
that exposure to PM2.5 emissions near roadways, dominated by
mobile sources, are associated with potentially serious health effects.
For instance, a recent study found associations between concentrations
of cardiac risk factors in the blood of healthy young police officers
and PM2.5 concentrations measured in vehicles.\32\ Also, a
number of studies have shown associations between residential or school
outdoor concentrations of some

constituents of fine particles found in motor vehicle exhaust and
adverse respiratory outcomes, including asthma prevalence in children
who live near major roadways.33 34 35 Although the engines
considered in this proposal differ with those in these studies with
respect to their applications and fuel qualities, these studies provide
an indication of the types of health effects that might be expected to
be associated with personal exposure to PM2.5 emissions from
Category 3 marine engines. By reducing their contribution to
PM2.5 inventories, the emissions controls under
consideration also would reduce exposure to these emissions,
specifically exposure near marine ports and shipping routes.
---------------------------------------------------------------------------

    \31\ Riekider, M.; Cascio, W.E.; Griggs, T.R.; Herbst, M.C.;
Bromberg, P.A.; Neas, L.; Williams, R.W.; Devlin, R.B. (2003)
Particulate Matter Exposures in Cars is Associated with
Cardiovascular Effects in Healthy Young Men. Am. J. Respir. Crit.
Care Med. 169: 934-940.
    \32\ Riediker, M.; Cascio, W.E.; Griggs, T.R.; et al. (2004)
Particulate matter exposure in cars is associated with
cardiovascular effects in healthy young men. Am J Respir Crit Care
Med 169: 934-940.
    \33\ Van Vliet, P.; Knape, M.; de Hartog, J.; Janssen, N.;
Harssema, H.; Brunekreef, B. (1997). Motor vehicle exhaust and
chronic respiratory symptoms in children living near freeways. Env.
Research 74: 122-132.
    \34\ Brunekreef, B., Janssen, N.A.H.; de Hartog, J.; Harssema,
H.; Knape, M.; van Vliet, P. (1997). Air pollution from truck
traffic and lung function in children living near roadways.
Epidemiology 8:298-303.
    \35\ Kim, J.J.; Smorodinsky, S.; Lipsett, M.; Singer, B.C.;
Hodgson, A.T.; Ostro, B (2004). Traffic-related air pollution near
busy roads: The East Bay children's respiratory health study. Am. J.
Respir. Crit. Care Med. 170: 520-526.
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2. Ozone
    The emissions reduction program under consideration for Category 3
marine engines would reduce the contribution of these engines
NOX inventories. These engines currently have high
NOX emissions due to the size of the engine and because they
are relatively uncontrolled. NOX contributes to the
formation of ground-level ozone pollution or smog. People in many areas
across the U.S. continue to be exposed to unhealthy levels of ambient
ozone.
(a) Background
    Ground-level ozone pollution is formed by the reaction of VOCs and
NOX in the atmosphere in the presence of heat and sunlight.
These two pollutants, often referred to as ozone precursors, are
emitted by many types of pollution sources, such as highway and nonroad
motor vehicles and engines, power plants, chemical plants, refineries,
makers of consumer and commercial products, industrial facilities, and
smaller ``area'' sources.
    The science of ozone formation, transport, and accumulation is
complex.\36\ Ground-level ozone is produced and destroyed in a cyclical
set of chemical reactions, many of which are sensitive to temperature
and sunlight. When ambient temperatures and sunlight levels remain high
for several days and the air is relatively stagnant, ozone and its
precursors can build up and result in more ozone than typically would
occur on a single high-temperature day. Ozone also can be transported
from pollution sources into areas hundreds of miles downwind, resulting
in elevated ozone levels even in areas with low local VOC or
NOX emissions.
---------------------------------------------------------------------------

    \36\ U.S. EPA Air Quality Criteria for Ozone and Related
Photochemical Oxidants (Final). U.S. Environmental Protection
Agency, Washington, D.C., EPA 600/R-05/004aF-cF, 2006. This document
may be accessed electronically at: http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_cd.html.
 This document is available in

Docket EPA-HQ-OAR-2007-0121.
---------------------------------------------------------------------------

    The highest levels of ozone are produced when both VOC and
NOX emissions are present in significant quantities on clear
summer days. Relatively small amounts of NOX enable ozone to
form rapidly when VOC levels are relatively high, but ozone production
is quickly limited by removal of the NOX. Under these
conditions NOX reductions are highly effective in reducing
ozone while VOC reductions have little effect. Such conditions are
called ``NOX-limited''. Because the contribution of VOC
emissions from biogenic (natural) sources to local ambient ozone
concentrations can be significant, even some areas where man-made VOC
emissions are relatively low can be NOX limited.
    When NOX levels are relatively high and VOC levels
relatively low, NOX forms inorganic nitrates (i.e.,
particles) but relatively little ozone. Such conditions are called
``VOC-limited.'' Under these conditions, VOC reductions are effective
in reducing ozone, but NOX reductions can actually increase
local ozone under certain circumstances. Even in VOC-limited urban
areas, NOX reductions are not expected to increase ozone
levels if the NOX reductions are sufficiently large.
    Rural areas are usually NOX-limited, due to the
relatively large amounts of biogenic VOC emissions in many rural areas.
Urban areas can be either VOC- or NOX-limited, or a mixture
of both, in which ozone levels exhibit moderate sensitivity to changes
in either pollutant. Ozone concentrations in an area also can be
lowered by the reaction of nitric oxide with ozone, forming nitrogen
dioxide (NO2); as the air moves downwind and the cycle
continues, the NO2 forms additional ozone. The importance of
this reaction depends, in part, on the relative concentrations of
NOX, VOC, and ozone, all of which change with time and
location.
    The current ozone NAAQS has an 8-hour averaging time. The 8-hour
ozone NAAQS is met at an ambient air quality monitoring site when the
average of the annual fourth-highest daily maximum 8-hour average ozone
concentration over three years is less than or equal to 0.084 ppm. On
June 20, 2007 EPA proposed to strengthen the ozone NAAQS. The proposed
revisions reflect new scientific evidence about ozone and its effects
on public health and welfare.\37\ The final ozone NAAQS rule is
scheduled for March 2008.
---------------------------------------------------------------------------

    \37\ EPA proposes to set the 8-hour primary ozone standard to a
level within the range of 0.070-0.075 ppm. The agency also requests
comments on alternative levels of the 8-hour primary ozone standard,
within a range from 0.060 ppm up to and including retention of the
current standard (0.084 ppm). EPA also proposes two options for the
secondary ozone standard. One option would establish a new form of
standard designed specifically to protect sensitive plants from
damage caused by repeated ozone exposure throughout the growing
season. This cumulative standard would add daily ozone
concentrations across a three month period. EPA is proposing to set
the level of the cumulative standard within the range of 7 to 21
ppm-hours. The other option would follow the current practice of
making the secondary standard equal to the proposed 8-hour primary
standard.
---------------------------------------------------------------------------

(b) Health Effects of Ozone
    The health and welfare effects of ozone are well documented and are
assessed in EPA's 2006 ozone Air Quality Criteria Document (ozone AQCD)
and EPA staff papers.\38\ \39\ Ozone can irritate the respiratory
system, causing coughing, throat irritation, and/or uncomfortable
sensation in the chest. 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 activity. Ozone can
also aggravate asthma, leading to more asthma attacks that require a
doctor's attention and/or the use of additional medication. Animal
toxicological evidence indicates that with repeated exposure, ozone can
inflame and damage the lining of the lungs, which may lead to permanent
changes in lung tissue and irreversible reductions in lung function.
People who are more susceptible to effects associated with

exposure to ozone include children, the elderly, and individuals with
respiratory disease such as asthma. As of the 2006 review, there was
suggestive evidence that certain people may have greater genetic
susceptibility. Those with greater exposures to ozone, for instance due
to time spent outdoors (e.g., children and outdoor workers), are also
of concern.
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    \38\ U.S. EPA Air Quality Criteria for Ozone and Related
Photochemical Oxidants (Final). U.S. Environmental Protection
Agency, Washington, D.C., EPA 600/R-05/004aF-cF, 2006. This document
is available in Docket EPA-HQ-OAR-2007-0121. This document may be
accessed electronically at: http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_cd.html
.

    \39\ U.S. EPA (2006) Review of the National Ambient Air Quality
Standards for Ozone, Policy Assessment of Scientific and Technical
Information. OAQPS Staff Paper Second Draft.EPA-452/D-05-002. This
document is available in Docket EPA-HQ-OAR-2007-0121. This document
is available electronically at: http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_sp.html
.

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    The recent ozone AQCD also examined relevant new scientific
information which has emerged in the past decade, including the impact
of ozone exposure on such health effect indicators as changes in lung
structure and biochemistry, inflammation of the lungs, exacerbation and
causation of asthma, respiratory illness-related school absence,
hospital admissions and premature mortality. Animal toxicological
studies have suggested potential interactions between ozone and PM with
increased responses observed to mixtures of the two pollutants compared
to either ozone or PM alone. The respiratory morbidity observed in
animal studies along with the evidence from epidemiologic studies
supports a causal relationship between acute ambient ozone exposures
and increased respiratory-related emergency room visits and
hospitalizations in the warm season. In addition, there is suggestive
evidence of a contribution of ozone to cardiovascular-related morbidity
and non-accidental and cardiopulmonary mortality.
3. Air Toxics
    People experience elevated risk of cancer and other noncancer
health effects from exposure to air toxics. Mobile sources are
responsible for a significant portion of this exposure. According to
the National Air Toxic Assessment (NATA) for 1999, mobile sources,
including Category 3 marine engines, were responsible for 44 percent of
outdoor toxic emissions and almost 50 percent of the cancer risk among
the 133 pollutants quantitatively assessed in the 1999 NATA. Benzene is
the largest contributor to cancer risk of all the assessed pollutants
and mobile sources were responsible for about 68 percent of all benzene
emissions in 1999. Although the 1999 NATA did not quantify cancer risks
associated with exposure to diesel exhaust, EPA has concluded that
diesel exhaust ranks with the other air toxic substances that the
national-scale assessment suggests pose the greatest relative risk.
    According to the 1999 NATA, nearly the entire U.S. population was
exposed to an average level of air toxics that has the potential for
adverse respiratory noncancer health effects. This potential was
indicated by a hazard index (HI) greater than 1.\40\ Mobile sources
were responsible for 74 percent of the potential noncancer hazard from
outdoor air toxics in 1999. About 91 percent of this potential
noncancer hazard was from acrolein; \41\ however, the confidence in the
RfC for acrolein is medium \42\ and confidence in NATA estimates of
population noncancer hazard from ambient exposure to this pollutant is
low.\43\ It is important to note that NATA estimates of noncancer
hazard do not include the adverse health effects associated with
particulate matter identified in EPA's Particulate Matter Air Quality
Criteria Document. Gasoline and diesel engine emissions contribute
significantly to with particulate matter concentration.
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    \40\ To express chronic noncancer hazards, we used the RfC as
part of a calculation called the hazard quotient (HQ), which is the
ratio between the concentration to which a person is exposed and the
RfC. (RfC is defined by EPA as, ``an estimate of a continuous
inhalation exposure to the human population, including sensitive
subgroups, with uncertainty spanning perhaps an order of magnitude,
that is likely to be without appreciable risks of deleterious
noncancer effects during a lifetime.'') A value of the HQ less than
one indicates that the exposure is lower than the RfC and that no
adverse health effects would be expected. Combined noncancer hazards
were calculated using the hazard index (HI), defined as the sum of
hazard quotients for individual air toxic compounds that affect the
same target organ or system. As with the hazard quotient, a value of
the HI at or below 1.0 will likely not result in adverse effects
over a lifetime of exposure. However, a value of the HI greater than
1.0 does not necessarily suggest a likelihood of adverse effects.
Furthermore, the HI cannot be translated into a probability that
adverse effects will occur and is not likely to be proportional to
risk.
    \41 \ U.S. EPA. U.S. EPA (2006) National-Scale Air Toxics
Assessment for 1999. This material is available electronically at
http://www.epa.gov/ttn/atw/nata1999/risksum.html.

    \42\ U.S. EPA (2003) Integrated Risk Information System File of
Acrolein. National Center for Environmental Assessment, Office of
Research and Development, Washington, DC 2003. This material is
available electronically at http://www.epa.gov/iris/subst/0364.htm.

    \43\ U.S. EPA (2006) National-Scale Air Toxics Assessment for
1999. This material is available electronically at http://www.epa.gov/ttn/atw/nata1999/risksum.html
.

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    It should be noted that the NATA modeling framework has a number of
limitations which prevent its use as the sole basis for setting
regulatory standards. These limitations and uncertainties are discussed
on the 1999 NATA Web site.\44\ Even so, this modeling framework is very
useful in identifying air toxic pollutants and sources of greatest
concern, setting regulatory priorities, and informing the decision
making process.
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    \44\ U.S. EPA (2006) National-Scale Air Toxics Assessment for
1999. http://www.epa.gov/ttn/atw/nata1999.

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    The following section provides a brief overview of air toxics which
are associated with nonroad engines, including Category 3 marine
engines, and provides a discussion of the health risks associated with
each air toxic.
(a) Diesel Exhaust (DE)
    Category 3 marine engines emit diesel exhaust (DE), a complex
mixture comprised of carbon dioxide, oxygen, nitrogen, water vapor,
carbon monoxide, nitrogen compounds, sulfur compounds and numerous low-
molecular-weight hydrocarbons. A number of these gaseous hydrocarbon
components are individually known to be toxic including aldehydes,
benzene and 1,3-butadiene. The diesel particulate matter (DPM) present
in diesel exhaust consists of fine particles (<  2.5 [mu]m), including a
subgroup with a large number of ultrafine particles (<  0.1 [mu]m).
These particles have large surface area which makes them an excellent
medium for adsorbing organics and their small size makes them highly
respirable and able to reach the deep lung. Many of the organic
compounds present on the particles and in the gases are individually
known to have mutagenic and carcinogenic properties. Diesel exhaust
varies significantly in chemical composition and particle sizes between
different engine types (heavy-duty, light-duty), engine operating
conditions (idle, accelerate, decelerate), and fuel formulations (high/
low sulfur fuel).\45\ After being emitted in the engine exhaust, diesel
exhaust undergoes dilution as well as chemical and physical changes in
the atmosphere. The lifetime for some of the compounds present in
diesel exhaust ranges from hours to days.
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    \45\ U.S. EPA (2002) Health Assessment Document for Diesel
Engine Exhaust. EPA/600/8-90/057F Office of Research and
Development, Washington DC. Pp1-1 1-2. This document is available in
Docket EPA-HQ-OAR-2007-0121. This document is available
electronically at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060
.

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(1) Diesel Exhaust: Potential Cancer Effect of Diesel Exhaust
    In EPA's 2002 Diesel Health Assessment Document (Diesel HAD),\46\
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, California EPA, and the U.S.
Department of Health and Human Services) have made similar
classifications. However, EPA also 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 limited quantitative exposure histories in occupational groups
investigated for lung cancer.
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    \46\ 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 in Docket
EPA-HQ-OAR-2007-0121.
    This document is available electronically at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060
.

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    For the Diesel HAD, EPA reviewed 22 epidemiologic studies on the
subject of the carcinogenicity of workers exposed to diesel exhaust in
various occupations, finding increased lung cancer risk, although not
always statistically significant, in 8 out of 10 cohort studies and 10
out of 12 case-control studies within several industries, including
railroad workers. Relative risk for lung cancer associated with
exposure ranged from 1.2 to 1.5, although a few studies show relative
risks as high as 2.6. Additionally, the Diesel HAD also relied on two
independent meta-analyses, which examined 23 and 30 occupational
studies respectively, which found statistically significant increases
in smoking-adjusted relative lung cancer risk associated with diesel
exhaust, of 1.33 to 1.47. These meta-analyses demonstrate the effect of
pooling many studies and in this case show the positive relationship
between diesel exhaust exposure and lung cancer across a variety of
diesel exhaust-exposed occupations.47 48 49
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    \47\ U.S. EPA (2002) Health Assessment Document for Diesel
Engine Exhaust. EPA/6008-90/057F Office of Research and Development,
Washington DC. This document is available in Docket EPA-HQ-OAR-2007-
0121.
    \48\ Bhatia, R., Lopipero, P., Smith, A. (1998) Diesel exposure
and lung cancer. Epidemiology 9(1):84-91.
    \49\ Lipsett, M: Campleman, S; (1999) Occupational exposure to
diesel exhaust and lung cancer: a meta-analysis. Am J Public Health
80(7): 1009-1017.
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    In the absence of a cancer unit risk, the Diesel HAD sought to
provide additional insight into the significance of the diesel exhaust-
cancer hazard by estimating possible ranges of risk that might be
present in the population. An exploratory analysis was used to
characterize a possible risk range by comparing a typical environmental
exposure level for highway diesel sources to a selected range of
occupational exposure levels. The occupationally observed risks were
then proportionally scaled 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 to as
high as 10-3, reflecting 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- or 10-5, and a zero
risk from diesel exhaust exposure was not ruled out.
    Retrospective health studies of railroad workers have played an
important part in determining that diesel exhaust is a likely human
carcinogen. Key evidence of the diesel exhaust exposure linkage to lung
cancer comes from two retrospective case-control studies of railroad
workers which are discussed at length in the Diesel HAD.
(2) Diesel Exhaust: Other Health Effects
    Noncancer health effects of acute and chronic exposure to diesel
exhaust emissions are also of concern to the Agency. EPA derived an RfC
from consideration of four well-conducted chronic rat inhalation
studies showing adverse pulmonary effects.50 51 52 53 The
RfC is 5 [mu]g/m\3\ for diesel exhaust as measured by diesel PM. This
RfC does not consider allergenic effects such as those associated with
asthma or immunologic effects. There is growing evidence, discussed in
the Diesel HAD, that exposure to diesel exhaust can exacerbate these
effects, but the exposure-response data were found to be lacking to
derive an RfC. The EPA Diesel HAD states, ``With DPM [diesel
particulate matter] being a ubiquitous component of ambient PM, there
is an uncertainty about the adequacy of the existing DE [diesel
exhaust] noncancer database to identify all of the pertinent DE-caused
noncancer health hazards. (p. 9-19).
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    \50\ Ishinishi, N; Kuwabara, N; Takaki, Y; et al. (1988) Long-
term inhalation experiments on diesel exhaust. In: Diesel exhaust
and health risks. Results of the HERP studies. Ibaraki, Japan:
Research Committee for HERP Studies; pp. 11-84.
    \51\ Heinrich, U; Fuhst, R; Rittinghausen, S; et al. (1995)
Chronic inhalation exposure of Wistar rats and two different strains
of mice to diesel engine exhaust, carbon black, and titanium
dioxide. Inhal. Toxicol. 7:553-556.
    \52\ Mauderly, JL; Jones, RK; Griffith, WC; et al. (1987) Diesel
exhaust is a pulmonary carcinogen in rats exposed chronically by
inhalation. Fundam. Appl. Toxicol. 9:208-221.
    \53\ Nikula, KJ; Snipes, MB; Barr, EB; et al. (1995) Comparative
pulmonary toxicities and carcinogenicities of chronically inhaled
diesel exhaust and carbon black in F344 rats. Fundam. Appl. Toxicol.
25:80-94.
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(3) Ambient PM2.5 Levels and Exposure to Diesel Exhaust PM
    The Diesel HAD briefly summarizes health effects associated with
ambient PM and discusses the EPA's annual NAAQS of 15 [mu]g/m\3\. In
addition, both the 2004 AQCD and the 2005 Staff Paper for PM2.5
have more recent information. There is a much more extensive body of
human data showing a wide spectrum of adverse health effects associated
with exposure to ambient PM, of which diesel exhaust is an important
component. The PM2.5 NAAQS is designed to provide protection
from the noncancer and premature mortality effects of PM2.5
as a whole, of which diesel PM is a constituent.
(4) Diesel Exhaust PM Exposures
    Exposure of people to diesel exhaust depends on their various
activities, the time spent in those activities, the locations where
these activities occur, and the levels of diesel exhaust pollutants in
those locations. The major difference between ambient levels of diesel
particulate and exposure levels for diesel particulate is that exposure
accounts for a person moving from location to location, proximity to
the emission source, and whether the exposure occurs in an enclosed
environment.
Occupational Exposures
    Occupational exposures to diesel exhaust from mobile sources,
including Category 3 marine engines, can be several orders of magnitude
greater than typical exposures in the non-occupationally exposed
population.
    Over the years, diesel particulate exposures have been measured for
a number of occupational groups resulting in a wide range of exposures
from 2 to 1,280 [mu]g/m\3\ for a variety of occupations. Studies have
shown that miners and railroad workers typically have higher diesel
exposure levels than other occupational groups studied, including
firefighters, truck dock workers, and truck drivers (both short and
long haul).\54\ As discussed in the Diesel HAD, the National Institute
of Occupational Safety and Health (NIOSH) has estimated a total of
1,400,000 workers are occupationally exposed to diesel exhaust from on-
road and nonroad vehicles.
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    \54\ Diesel HAD Page 2-110, 8-12; Woskie, SR; Smith, TJ;
Hammond, SK: et al. (1988a) Estimation of the DE exposures of
railroad workers: II. National and historical exposures. Am J Ind
Med 12:381-394.

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Elevated Concentrations and Ambient Exposures in Mobile Source-Impacted
Areas
    Regions immediately downwind of marine ports and shipping channels
experience elevated ambient concentrations of directly-emitted
PM2.5 from Category 3 marine engines. Due to the unique
nature of marine ports, emissions from a large number of Category 3
marine engines are concentrated in a relatively small area.
    A recent study conducted by the California Air Resources Board
(CARB) examined the air quality impacts of railroad operations at the
J.R. Davis Rail Yard, the largest service and maintenance rail facility
in the western United States.\55\ This is relevant in that locomotives
use diesel engines similar to those used in marine vessels. The yard
occupies 950 acres along a one-quarter mile wide and four mile long
section of land in Roseville, CA. The study developed an emissions
inventory for the facility for the year 2000 and modeled ambient
concentrations of diesel PM using a well-accepted dispersion model
(ISCST3). The study estimated substantially elevated concentrations in
an area 5,000 meters from the facility, with higher concentrations
closer to the rail yard. Using local meteorological data, annual
average contributions from the rail yard to ambient diesel PM
concentrations under prevailing wind conditions were 1.74, 1.18, 0.80,
and 0.25 [mu]g/m\3\ at receptors located 200, 500, 1000, and 5000
meters from the yard, respectively. Several tens of thousands of people
live within the area estimated to experience substantial increases in
annual average ambient PM2.5 as a result of rail yard
emissions.
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    \55\ Hand, R.; Pingkuan, D.; Servin, A.; Hunsaker, L.; Suer, C.
(2004) Roseville rail yard study. California Air Resources Board.
[Online at http://www.arb.ca.gov/diesel/documents/rrstudy.htm]

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    Another study from CARB evaluated air quality impacts of diesel
engine emissions within the Ports of Long Beach and Los Angeles in
California, one of the largest ports in the U.S.\56\ The study found
that ocean going vessels comprised 53% of the diesel PM emissions while
ship auxiliary engines' hoteling comprised another 20% of PM emissions
for the marine ports. Like the earlier rail yard study, the port study
employed the ISCST3 dispersion model. Also using local meteorological
data, annual average concentrations were substantially elevated over an
area exceeding 200,000 acres. Because the ports are located near
heavily-populated areas, the modeling indicated that over 700,000
people lived in areas with at least 0.3 [mu]g/m\3\ of port-related
diesel PM in ambient air, about 360,000 people lived in areas with at
least 0.6 [mu]g/m\3\ of diesel PM, and about 50,000 people lived in
areas with at least 1.5 ug/m\3\ of ambient diesel PM directly from the
port. The study found that impacts could be discerned up to 15 miles
from the marine port.
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    \56\ Di, P.; Servin, A.; Rosenkranz, K.; Schwehr, B.; Tran, H.
(2006) Diesel particulate matter exposure assessment study for the
Ports of Los Angeles and Long Beach. California Air Resources Board.
[Online at http://www.arb.ca.gov/msprog/offroad/marinevess/marinevess.htm
]

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    Overall, while these studies focus on only two large marine port
and railroad facilities, they highlight the substantial contribution
these facilities make to elevated ambient concentrations in populated
areas.
    We initiated a study in 2006 to better understand the populations
that are living near rail yards and marine ports nationally. As part of
this effort, a computer geographic information system (GIS) is being
used to identify the locations and property boundaries of these
facilities nationally, and to determine the size and demographic
characteristics of the population living near these facilities. We
anticipate that the results of this study will be completed in late
2007 and we intend to add this report to the public docket.
(b) Other Air Toxics-Benzene, 1,3-butadiene, Formaldehyde,
Acetaldehyde, Acrolein, POM, Naphthalene
    Category 3 marine engine emissions contribute to ambient levels of
other air toxics known or suspected as human or animal carcinogens, or
that have non-cancer health effects. These other compounds include
benzene, 1,3-butadiene, formaldehyde, acetaldehyde, acrolein,
polycyclic organic matter (POM), and naphthalene. All of these
compounds, except acetaldehyde, were identified as national or regional
risk drivers in the 1999 National-Scale Air Toxics Assessment (NATA).
That is, for a significant portion of the population, these compounds
pose a significant portion of the total cancer and noncancer risk from
breathing outdoor air toxics. Furthermore, a significant portion of
total nationwide emissions of these pollutants result from mobile
sources. However, EPA does not have high confidence in the NATA data
for all these compounds. Reducing the emissions from Category 3 marine
engines would help reduce exposure to these harmful substances.
    Air toxics can cause a variety of cancer and noncancer health
effects. A number of the mobile source air toxic pollutants described
in this section are known or likely to pose a cancer hazard in humans.
Many of these compounds also cause adverse noncancer health effects
resulting from inhalation exposures. These include neurological,
cardiovascular, liver, kidney, and respiratory effects as well as
effects on the immune and reproductive systems.

C. Other Environmental Effects

    There are a number of public welfare effects associated with the
presence of ozone and PM2.5 in the ambient air including the
impact of PM2.5 on visibility and materials and the impact
of ozone on plants, including trees, agronomic crops and urban
ornamentals.
1. Visibility
    Visibility can be defined as the degree to which the atmosphere is
transparent to visible light. Visibility impairment manifests in two
principal ways: as local visibility impairment and as regional
haze.\57\ Local visibility impairment may take the form of a localized
plume, a band or layer of discoloration appearing well above the
terrain as a result of complex local meteorological conditions.
Alternatively, local visibility impairment may manifest as an urban
haze, sometimes referred to as a ``brown cloud.'' This urban haze is
largely caused by emissions from multiple sources in the urban areas
and is not typically attributable to only one nearby source or to long-
range transport. The second type of visibility impairment, regional
haze, usually results from multiple pollution sources spread over a
large geographic region. Regional haze can impair visibility in large
regions and across states.
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    \57\ See discussion in U.S. EPA , National Ambient Air Quality
Standards for Particulate Matter; Proposed Rule; January 17, 2006,
Vol71 p 2676. This document is available in Docket EPA-HQ-OAR-2007-
0121. This information is available electronically at http://epa.gov/fedrgstr/EPA-AIR/2006/January/Day-17/a177.pdf
.

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    Visibility is important because it has direct significance to
people's enjoyment of daily activities in all parts of the country.
Individuals value good visibility for the well-being it provides them
directly, where they live and work, and in places where they enjoy
recreational opportunities. Visibility is also highly valued in
significant natural areas such as national parks and wilderness areas
and special emphasis is given to protecting visibility in these areas.
For more information on visibility

see the final 2004 PM AQCD \58\ as well as the 2005 PM Staff Paper.\59\
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    \58\ U.S. EPA (2004) Air Quality Criteria for Particulate Matter
(Oct 2004), Volume I Document No. EPA600/P-99/002aF and Volume II
Document No. EPA600/P-99/002bF. This document is available in Docket
EPA-HQ-OAR-2007-0121.
    \59\ U.S. EPA (2005) Review of the National Ambient Air Quality
Standard for Particulate Matter: Policy Assessment of Scientific and
Technical Information, OAQPS Staff Paper. EPA-452/R-05-005. This
document is available in Docket EPA-HQ-OAR-2007-0121.
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    Fine particles are the major cause of reduced visibility in parts
of the United States. EPA is pursuing a two-part strategy to address
visibility. First, to address the welfare effects of PM on visibility,
EPA set secondary PM2.5 standards which would act in
conjunction with the establishment of a regional haze program. In
setting this secondary standard EPA concluded that PM2.5
causes adverse effects on visibility in various locations, depending on
PM concentrations and factors such as chemical composition and average
relative humidity. Second, section 169 of the Clean Air Act provides
additional authority to address existing visibility impairment and
prevent future visibility impairment in the 156 national parks, forests
and wilderness areas categorized as mandatory class I federal areas (62
FR 38680-38681, July 18, 1997).\60\ In July 1999 the regional haze rule
(64 FR 35714) was put in place to protect the visibility in mandatory
class I federal areas. Visibility can be said to be impaired in both
PM2.5 nonattainment areas and mandatory class I federal
areas.
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    \60\ These areas are defined in section 162 of the Act as those
national parks exceeding 6,000 acres, wilderness areas and memorial
parks exceeding 5,000 acres, and all international parks which were
in existence on August 7, 1977.
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    Category 3 marine engines contribute to visibility concerns in
these areas through their primary PM2.5 emissions and their
NOX and SO2 emissions which contribute to the
formation of secondary PM2.5.
    Recently designated PM2.5 nonattainment areas indicate
that, as of June 20, 2007, almost 90 million people live in
nonattainment areas for the 1997 PM2.5 NAAQS. Thus, at least
these populations would likely be experiencing visibility impairment,
as well as many thousands of individuals who travel to these areas. In
addition, while visibility trends have improved in mandatory Class I
federal areas the most recent data show that these areas continue to
suffer from visibility impairment. In summary, visibility impairment is
experienced throughout the U.S., in multi-state regions, urban areas,
and remote mandatory class I federal areas.61 62
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    \61\ U.S. EPA, Air Quality Designations and Classifications for
the Fine Particles (PM2.5) National Ambient Air Quality
Standards, December 17, 2004. (70 FR 943, Jan 5. 2005) This document
is available in Docket EPA-HQ-OAR-2007-0121. This document is also
available on the web at: http://www.epa.gov/pmdesignations/.

    \62\ U.S. EPA. Regional Haze Regulations, July 1, 1999. (64 FR
35714, July 1, 1999) This document is available in Docket EPA-HQ-
OAR-2007-0121.
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2. Plant and Ecosystem Effects of Ozone
    Ozone contributes to many environmental effects, with impacts to
plants and ecosystems being of most concern. Ozone can produce both
acute and chronic injury in sensitive species depending on the
concentration level and the duration of the exposure. Ozone effects
also tend to accumulate over the growing season of the plant, so that
even lower concentrations experienced for a longer duration have the
potential to create chronic stress on vegetation. Ozone damage to
plants includes visible injury to leaves and a reduction in food
production through impaired photosynthesis, both of which can lead to
reduced crop yields, forestry production, and use of sensitive
ornamentals in landscaping. In addition, the reduced food production in
plants and subsequent reduced root growth and storage below ground, can
result in other, more subtle plant and ecosystems impacts. These
include increased susceptibility of plants to insect attack, disease,
harsh weather, interspecies competition and overall decreased plant
vigor. The adverse effects of ozone on forest and other natural
vegetation can potentially lead to species shifts and loss from the
affected ecosystems, resulting in a loss or reduction in associated
ecosystem goods and services. Lastly, visible ozone injury to leaves
can result in a loss of aesthetic value in areas of special scenic
significance like national parks and wilderness areas. The final 2006
ozone Air Quality Criteria Document (ozone AQCD) \63\ presents more
detailed information on ozone effects on vegetation and ecosystems.
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    \63\ U.S. EPA Air Quality Criteria for Ozone and Related
Photochemical Oxidants (Final). U.S. Environmental Protection
Agency, Washington, DC, EPA 600/R-05/004aF-cF, 2006. This document
is available in Docket EPA-HQ-OAR-2007-0121. This document may be
accessed electronically at: http://www.epa.gov/ttn/naaqs/standards/ozone/s_o3_cr_cd.html
.

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    As discussed above, Category 3 marine engine emissions of
NOX contribute to ozone and therefore the NOX
standards discussed in this action would help reduce crop damage and
stress on vegetation from ozone.
3. Acid Deposition
    Acid deposition, or acid rain as it is commonly known, occurs when
NOX and SO2 react in the atmosphere with water,
oxygen and oxidants to form various acidic compounds that later fall to
earth in the form of precipitation or dry deposition of acidic
particles. It contributes to damage of trees at high elevations and in
extreme cases may cause lakes and streams to become so acidic that they
cannot support aquatic life. In addition, acid deposition accelerates
the decay of building materials and paints, including irreplaceable
buildings, statues, and sculptures that are part of our nation's
cultural heritage.
    The proposed NOX and SOX standards would help
reduce acid deposition, thereby helping to reduce acidity levels in
lakes and streams throughout the coastal areas of our country and help
accelerate the recovery of acidified lakes and streams and the revival
of ecosystems adversely affected by acid deposition. Reduced acid
deposition levels will also help reduce stress on forests, thereby
accelerating reforestation efforts and improving timber production.
Deterioration of historic buildings and monuments, vehicles, and other
structures exposed to acid rain and dry acid deposition also will be
reduced, and the costs borne to prevent acid-related damage may also
decline. While the reduction in nitrogen acid deposition will be
roughly proportional to the reduction in NOX emissions, the
precise impact of new standards would differ across different areas.
4. Eutrophication and Nitrification
    The NOX standards discussed in this action would help
reduce the airborne nitrogen deposition that contributes to
eutrophication of watersheds, particularly in aquatic systems where
atmospheric deposition of nitrogen represents a significant portion of
total nitrogen loadings. Eutrophication is the accelerated production
of organic matter, particularly algae, in a water body. This increased
growth can cause numerous adverse ecological effects and economic
impacts, including nuisance algal blooms, dieback of underwater plants
due to reduced light penetration, and toxic plankton blooms. Algal and
plankton blooms can also reduce the level of dissolved oxygen, which
can adversely affect fish and shellfish populations. In recent decades,
human activities have greatly accelerated nutrient impacts, such as
nitrogen and phosphorus, causing excessive growth of algae and leading
to degraded water

quality and associated impairment of freshwater and estuarine resources
for human uses.\64\
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    \64\ Deposition of Air Pollutants to the Great Waters, Third
Report to Congress, June 2000, EPA-453/R-00-005. This document is
available in Docket EPA-HQ-OAR-2007-0121. It is also available at
http://www.epa.gov/oar/oaqps/gr8water/3rdrpt/obtain.html.

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    Severe and persistent eutrophication often directly impacts human
activities. For example, losses in the nation's fishery resources may
be directly caused by fishkills associated with low dissolved oxygen
and toxic blooms. Declines in tourism occur when low dissolved oxygen
causes noxious smells and floating mats of algal blooms create
unfavorable aesthetic conditions. Risks to human health increase when
the toxins from algal blooms accumulate in edible fish and shellfish,
and when toxins become airborne, causing respiratory problems due to
inhalation. According to the NOAA report, more than half of the
nation's estuaries have moderate to high expressions of at least one of
these symptoms--an indication that eutrophication is well developed in
more than half of U.S. estuaries.\65\
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    \65\ Bricker, Suzanne B., et al., National Estuarine
Eutrophication Assessment, Effects of Nutrient Enrichment in the
Nation's Estuaries, National Ocean Service, National Oceanic and
Atmospheric Administration, September, 1999.
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5. Materials Damage and Soiling
    The deposition of airborne particles can reduce the aesthetic
appeal of buildings and culturally important articles through soiling,
and can contribute directly (or in conjunction with other pollutants)
to structural damage by means of corrosion or erosion.\66\ Particles
affect materials principally by promoting and accelerating the
corrosion of metals, by degrading paints, and by deteriorating building
materials such as concrete and limestone. Particles contribute to these
effects because of their electrolytic, hygroscopic, and acidic
properties, and their ability to adsorb corrosive gases (principally
sulfur dioxide). The rate of metal corrosion depends on a number of
factors, including the deposition rate and nature of the pollutant; the
influence of the metal protective corrosion film; the amount of
moisture present; variability in the electrochemical reactions; the
presence and concentration of other surface electrolytes; and the
orientation of the metal surface. The PM standards discussed in this
action would help reduce the airborne particles that contribute to
materials damage and soiling.
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    \66\ U.S. EPA (2005) Review of the National Ambient Air Quality
Standards for Particulate Matter: Policy Assessment of Scientific
and Technical Information, OAQPS Staff Paper. This document is
available in Docket EPA-HQ-OAR-2007-0121.
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III. Relevant Clean Air Act Provisions

    Section 213 of the Clean Air Act (the Act) gives us the authority
to establish emission standards for nonroad engines and vehicles.
Section 213(a)(3) requires the Administrator to set (and from time to
time revise) standards for NOX, VOCs, or carbon monoxide
emissions from new nonroad engines, to reduce ambient levels of ozone
and carbon monoxide. That section specifies that the ``standards shall
achieve the greatest degree of emission reductions 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
lead time, noise, energy, and safety factors associated with the
application of such technology. Section 213(a)(4) authorizes the
Administrator to establish standards on new engines to control
emissions of pollutants, such as PM, which ``may reasonably be
anticipated to endanger public health and welfare.'' In setting
appropriate standards, EPA is instructed to take into account costs,
noise, safety, and energy factors.
    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 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.

IV. International Regulation of Air Pollution From Ships

    Annex VI to the International Convention for the Prevention of
Pollution from Ships (MARPOL) addresses air pollution from ships. Annex
VI was adopted by the Parties to MARPOL at a Diplomatic Conference on
September 26, 1997, and it went into force May 20, 2005. As of July 31,
2007, the Annex has been ratified by 44 countries, representing 74.1
percent of the world's merchant shipping tonnage.\67\
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    \67\ See http://www.imo.org Go to Conventions, Status of

Conventions--Summary.
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    Globally harmonized regulation of ship emissions is generally
recognized to be the preferred approach for addressing air emissions
from ocean-going vessels. It reduces costs for ship owners, since they
would not be required to comply with a patchwork of different standards
that could occur if each country was setting its own standards, and it
can simplify environmental protection for port and coastal states.
    The significance of international shipping to the United States can
be illustrated by port entrance statistics. In 1999, according to U.S.
Maritime Administration (MARAD) data, about 90 percent of annual
entrances to U.S. ports were made by foreign-flagged vessels (75,700
total entrances; 67,500 entrances by foreign vessels; entrances are for
vessels engaged in foreign trade and do not include Jones Act \68\
vessels). At the same time, however, only a small portion of those
vessels account for most of the visits. In 1999, of the 7,800 foreign
vessels that visited U.S. ports, about 12 percent accounted for about
50 percent of total vessel entrances; about 30 percent accounted for
about 75 percent of the vessel entrances.\69\
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    \68\ 46 USCS Appx Sec.  688.
    \69\ Final Regulatory Support Document: Control of Emissions
from New Marine Compression-Ignition Engines at or Above 30 Liters
per Cylinder. EPA420-R-03-004, January 2003, pg. 3-50. This document
is available at http://www.epa.gov/otaq/regs/nonroad/marine/ci/r03004.pdf.
 We will update these statistics for more recent years;

however, these results are not expected to change significantly
given the U.S. share of the ownership of ocean-going vessels. MARAD
data from 2005 indicates that while about 4.7 percent of all ocean-
going vessels are owned by citizens of the United States (5th
largest fleet) only about 1.9 percent of all ocean-going vessels are
flagged here. Also according to that data, while Greece, Japan,
China, and Germany account for the largest fleets in terms of
ownership (15.3, 13.0, 11, and 8.9 percent, respectively), Panama
and Liberia account for the largest fleets by flag (21.6 and 8.9
percent, respectively).
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    The emission control program contained in Annex VI was the first
step for the international control of air pollution from ships.
However, as early as the 1997 conference, many countries ``already
recognized that the NOX emission limits established in
Regulation 13 were very modest when compared with current technology
developments.'' \70\ Consequently, a Conference Resolution was adopted
at the 1997 conference that invited the Marine Environment Protection
Committee (MEPC) to review the NOX emission limits at a
minimum of five-year intervals after entry into force of the protocol
and, if appropriate, amend

the NOX limits to reflect more stringent controls.
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    \70\ Proposal to Initiate a Revision Process, Submitted by
Finland, Germany, Italy, the Netherlands, Norway, Sweden and the
United Kingdom. MEPC 53/4/4, 15 April 2005. Marine Environment
Protection Committee, 53rd Session, Agenda Item 4.
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    The United States began advocating a review of the NOX
emission limits in 1999.\71\ However, MEPC did not formally consider
the issue until 2005, after the Annex went into effect. Negotiations
for amendments to the Annex VI standards, including NOX and
SOX emission limits, officially began in April 2006, with
the most recent round of negotiations taking place in April 2007. The
United States submitted a paper to that meeting (April 2007 Bulk
Liquids and Gases Sub-Committee meeting, referred to as BLG-11) setting
out an approach for new international engine and fuel standards. That
approach forms the basis of the program outlined in this ANPRM.\72\
Discussions are expected to continue through Summer 2008 and are
expected to conclude at the October 2008 MEPC meeting. We will continue
to coordinate our national rule for Category 3 emission limits with our
activities at IMO.
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    \71\ Revision of the NOX Technical Code, Tier 2
Emission Limits for Diesel Marine Engines At or Above 130 kW,
submitted by the United States. MEPC 44/11/7, 24 December 1999.
Marine Environment Protection Committee, 44th Session, Agenda Item
11.
    \72\ ``Revision of the MARPOL Annex VI, the NOX
Technical Code and Related Guidelines; Development of Standards for
NOX, PM, and SOX,'' submitted by the United
States, BLG 11/5, Sub-Committee on Bulk Liquids and Gases, 11th
Session, Agenda Item 5, February 9, 2007, Docket ID EPA-HQ-OAR-2007-
0121-0034. This document is also available on our Web site: http://www.epa.gov/otaq/oceanvessels.com
.

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V. Potential Standards and Effective Dates

    Over the past several years, remarkable progress has been made for
land-based highway and nonroad diesel engines in reducing
NOX and PM emissions. Current EPA standards for those land-
based sources are anticipated to achieve emission reductions of more
than 90 percent relative to uncontrolled NOX and PM levels.
In contrast, Category 3 marine engines are subject to modest
NOX standards only. In this rulemaking, we are considering a
comprehensive program that would set long-term standards based on the
use of high-efficiency catalytic aftertreatment. These standards would
achieve substantial reductions in NOX, PM, and
SOX exhaust emissions.
    The program we are considering is based on the the U.S. Government
proposal to IMO, which consists of near- and long-term NOX
limits for new engines based on engine controls and aftertreatment
technology; NOX limits for certain existing engines based on
engine controls; and PM/SOX limits that can be achieved
through the use of exhaust gas cleaning or low sulfur fuel. To reduce
the costs of the international program, the long-term new engine
NOX limits and the PM/SOX limits would not apply
while ships are operating on the open ocean; instead, they would in
specified geographic areas to be defined under the treaty.
    This section describes in greater detail how we are considering
that emission control program for our federal action under the Clean
Air Act.

A. NOX Standards

    Tier 2 NOX limits: We are considering new NOX emission
standards for Category 3 marine diesel engines. As discussed in Section
VI, emission control technology for Category 3 marine engines has
progressed substantially in recent years. Significant reductions can be
achieved in the near term through in-cylinder controls with little or
no impact on overall vessel performance. These technologies include
traditional engine-out controls such as electronically controlled high
pressure common-rail fuel systems, turbocharger optimization,
compression-ratio changes, and electronically controlled exhaust
valves. Further emission reductions could be achieved through the use
of water-based technologies such as water emulsification, direct water
injection, or intake-air humidification or through exhaust gas
recirculation. We request comment on setting a near term NOX
emission standard requiring a reduction of 15 to 25 percent below the
current Tier 1 standard. We are considering applying this near term
standard to new engines as early as 2011.
    Tier 3 NOX limits: In the longer term, we believe that much greater
emission reductions could be achieved through the use of selective
catalytic reduction (SCR). More than 300 SCR systems have been
installed on marine vessels, some of which have been in operation for
more than 10 years and have accumulated 80,000 hours of operation.
While many of these applications have been limited to certain vessel
classes, we believe that the technology is feasible for application to
most engines given adequate lead time. As discussed in Section VI, SCR
systems are capable of reducing NOX on the order of 90 to 95
percent compared to current emission levels. We further believe that an
80 percent reduction from the Tier 2 levels discussed above is
achievable throughout the life of the vessel. We are requesting comment
on setting a NOX standard 80 percent below the Tier 2
standards in the 2016 timeframe. Low sulfur distillate fuel would help
in achieving these limits due to the impact of sulfur on catalyst
operation; however, we do not believe low sulfur fuel is necessary to
achieve these reductions. SCR systems have been used on residual fuel,
with sulfur levels as high as 2.5 to 3 percent. However low sulfur
distillate fuel would allow SCR systems to be smaller, more efficient,
less costly, and simpler to operate.
    NOX limits for existing engines: Due to the very long life of
ocean-going vessels and the availability of known in-cylinder technical
modifications that provide significant and cost-effective
NOX reductions, the U.S. proposal to IMO presents potential
NOX emission limits for engines on vessels built prior to
the Tier 1 limits. We are requesting comment on requiring engines on
these vessels to be retrofitted to meet the Tier 1 standard. The U.S.
submittal proposed that this requirement would start in 2012. Although
the Tier 1 standards went into effect in the United States in 2004,
manufacturers have been building engines with emissions that meet this
limit since 2000 due to the MARPOL Annex VI NOX standard.
Although the Annex VI standards did not go into force until 2005, they
apply to engines installed on vessels built on or after January 1,
2000.
    Engines may be retrofitted to achieve meaningful emission reduction
by applying technology used by manufacturers to meet the Tier 1 limits.
These technologies include slide-valve fuel injectors and injection
timing retard. Manufacturers have indicated that they can reduce
NOX emissions by approximately 20 percent using this
technology. However, some engines have higher baseline emissions than
average and would require more than a 20 percent emission reduction to
meet Tier 1 standards. Manufacturers have expressed concerns that they
would not necessarily be able to reduce emissions to the Tier 1
standards for such engines through a simple retrofit. Therefore, the
U.S. proposal to IMO considers a standard based on percent reduction
rather than an absolute numerical limit. Specifically, these engines
would need to be modified to reduce NOX emissions by 20
percent from their existing baseline emission rate. Alternatively, we
request comment on requiring vessel operators to perform a specific
action, such as a valve or injector change, that would be known to
achieve a particular NOX reduction. In this case, the
certification and compliance provisions would be based on the
completion of this action rather than achieving a specified emission
reduction.
    Over time, engine manufacturers have changed their engine platforms
as new

technologies have become available. Many of the technologies that can
be used to reduce NOX emissions on modern engines may not be
easily applied to older engine designs. Based on conversations with
engine manufacturers we believe that engines built in the mid-1980s and
later are compatible with the lower NOX components.
Therefore we are requesting comment on excluding engines installed on a
vessel prior to 1985 from this requirement. We request comment on what
generation of engines can be retrofitted to achieve NOX
reductions. Also, we request comment on the feasibility, costs, and
other business impacts that would result from retrofitting existing
engines to meet a NOX standard as discussed above.

B. PM and SOX Standards

    For PM and SOX emission control, we are considering
emission performance standards that would reflect the use of low-sulfur
distillate fuels or the use of exhaust gas cleaning technology, or a
combination of both. As discussed in Section VI, SOX
emissions and the majority of the direct PM emissions from Category 3
marine engines operated on residual fuels are a direct result of fuel
quality, most notably the sulfur in the fuel. In addition,
SOX emissions form secondary PM in the atmosphere. Other
components of residual fuel, such as ash and heavy metals, also
contribute directly to PM. Significant PM and SOX reductions
could be achieved by using low sulfur fuel residual fuel or distillate
fuel. Alternatively, direct and indirect sulfur-based PM can be reduced
through the use of a seawater scrubber in the exhaust system. Recent
demonstration projects have shown that scrubbers are capable of
reducing SOX emissions on the order of 95 percent and can
achieve substantial reductions in PM as well.
    We request comment on setting a PM standard on the order of 0.5 g/
kW-hr and a SOX standard on the order of 0.4 g/kW-hr. We
believe that the combination of these two performance-based standards
would be a cost-effective way to approach both primary and secondary PM
emission reductions because ship owners would have a variety of
mechanisms to achieve the standard, including fuel switching or the use
of emission scrubbers. This standard would apply as early as 2011 and
would result in more than a 90 percent reduction in SOX and
approximately a 50-70 percent reduction in PM. We request comment on
performance based PM and SOX standards for Category 3 marine
engines, what the standards should be, and an appropriate
implementation date. We also request comment on allowing vessel
operators the option to comply with the standards by simply using a
distillate fuel with a maximum allowable sulfur level, such as 1,000
ppm. Under this option, no exhaust emission testing would be required
to demonstrate compliance with the standard.

VI. Emission Control Technology

A. Engine-Based NOX Control

1. Traditional In-Cylinder Controls
    Engine manufacturers are meeting the Tier 1 NOX
standards \73\ for Category 3 marine engines today through traditional
in-cylinder fuel and air management approaches. These in-cylinder
emission control technologies include electronic controls, optimizing
the turbocharger, higher compression ratio, valve timing, and optimized
fuel injection which may include common rail systems, timing retard,
increased injection pressure, rate shaping, and changes to the number
and size of injector holes to increase fuel atomization. Although U.S.
standards became effective in 2004, most manufacturers began selling
marine engines in 2000 that met the MARPOL Annex VI NOX
standard in anticipation of its ratification.
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    \73\ This NOX standard is the same as the
internationally negotiated NOX standards established by
the International Maritime Organization (IMO) in Annex VI to the
International Convention on the Prevention of Pollution from Ships,
1973, as Modified by the Protocol of 1978 Relating Thereto (MARPOL).
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    Manufacturers have indicated that they would be able to use in-
cylinder engine control strategies to achieve further NOX
emission reductions beyond the Tier 1 standards. EUROMOT, which is an
association of engine manufacturers, submitted a proposal to the
International Maritime Organization for new Category 3 marine engine
NOX standards 2 g/kW-hr below the Tier 1 NOX
standard.\74\ In this submission, they pointed to the following
technologies for Category 3 marine engines operating on residual fuel:
Fuel injection timing, high compression ratio, modified valve timing on
4-stroke engines, late exhaust valve closing on 2-stroke engines, and
optimized fuel injection system and combustion chamber. EUROMOT stated
that the limiting factors for NOX design and optimization
are increases in low load smoke and thermal load, PM and CO2
emissions, fuel consumption, and concerns about engine reliability and
load acceptance. We request comment on potential emission reductions
beyond the Tier 1 NOX standards that may be achieved through
traditional in-cylinder technology and what the impact of the low
NOX designs would be on fuel consumption, maintenance, and
on PM exhaust emissions.
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    \74\ ``MARPOL Annex VI Revision--Proposals Related to Future
Emission Limits and Issues for Clarification,'' Submitted by EUROMOT
to the IMO Subcommittee on Bulk Liquids and Gases, BLG 10/14/12,
January 26, 2006, Docket ID EPA-HQ-OAR-2007-0121-0014.
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    Many of the same in-cylinder control technologies used to meet the
Tier 1 NOX standards can be used as retrofit technology on
existing engines built prior to the Tier 1 standards. An example of
this is retrofitting older fuel injectors with new injectors using
slide-valve nozzle tips. The slide-valve in the nozzle tip limits fuel
``dripping'' which leads to higher HC, PM, and smoke emissions and
engine fouling. This fuel nozzle can be combined with low-
NOX engine calibration to achieve about a 20 percent
reduction in NOX emissions through an engine retrofit.\75\
This retrofit is relatively simple on engine platforms similar to those
used for the Tier 1 compliant engines, but the slide-valve injectors
may not be compatible with older engines. We request comment on the
costs and other business impacts of retrofitting Category 3 marine
engines built before 2000 to meet the Tier 1 NOX standard.
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    \75\ Henningsen, S., ``2007 Panel Discussion on Emission
Reduction Solutions for Marine Vessels; Engine Technologies''
presentation by MAN B&W at the Clean Ships: Advanced Technology for
Clean Air Conference, February 8, 2007, Docket ID EPA-HQ-OAR-2007-
0121-0031.
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2. Water-Based Technologies
    NOX emissions from Category 3 marine engines can be
reduced by introducing water into the combustion process in combination
with appropriate in-cylinder controls. Water can be used in the
combustion process to lower the maximum combustion temperature, and
therefore lower NOX formation without a significant increase