States. \53\ 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.
---------------------------------------------------------------------------

    \53\ 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].

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

    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.\54\ 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/m3 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 [mu]g/m 3 of ambient diesel PM directly from
the port.
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    \54\ 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 have recently initiated a study to better understand the
populations that are living near rail yards and marine ports
nationally. As part of the study, 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
complete in 2007 and we intend to add this report to the public docket.
(a) Gaseous Air Toxics--Benzene, 1,3-butadiene, Formaldehyde,
Acetaldehyde, Acrolein, POM, Naphthalene
    Locomotive and marine diesel engine exhaust 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) and have significant inventory contributions from mobile
sources. 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. The reductions in locomotive
and marine diesel engine emissions proposed in this rulemaking 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 chronic,\55\

subchronic,\56\ or acute \57\ inhalation exposures. These include
neurological, cardiovascular, liver, kidney, and respiratory effects as
well as effects on the immune and reproductive systems.
---------------------------------------------------------------------------

    \55\ Chronic exposure is defined in the glossary of the
Integrated Risk Information (IRIS) database (http://www.epa.gov/iris
) as repeated exposure by the oral, dermal, or inhalation route

for more than approximately 10 percent of the life span in humans
(more than approximately 90 days to 2 years in typically used
laboratory animal species).
    \56\ Defined in the IRIS database as exposure to a substance
spanning approximately 10 percent of the lifetime of an organism.
    \57\ Defined in the IRIS database as exposure by the oral,
dermal, or inhalation route for 24 hours or less.
---------------------------------------------------------------------------

    Benzene: The EPA's Integrated Risk Information (IRIS) database
lists benzene as a known human carcinogen (causing leukemia) by all
routes of exposure, and that exposure is associated with additional
health effects, including genetic changes in both humans and animals
and increased proliferation of bone marrow cells in
mice.58 59 60 EPA states in its IRIS database that data
indicate a causal relationship between benzene exposure and acute
lymphocytic leukemia and suggests a relationship between benzene
exposure and chronic non-lymphocytic leukemia and chronic lymphocytic
leukemia. A number of adverse noncancer health effects including blood
disorders, such as preleukemia and aplastic anemia, have also been
associated with long-term exposure to benzene.61 62 The most
sensitive noncancer effect observed in humans, based on current data,
is the depression of the absolute lymphocyte count in
blood.63 64 In addition, recent work, including studies
sponsored by the Health Effects Institute (HEI), provides evidence that
biochemical responses are occurring at lower levels of benzene exposure
than previously known.65 66 67 68 EPA's IRIS program has not
yet evaluated these new data.
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    \58\ U.S. EPA. 2000. Integrated Risk Information System File for
Benzene. This material is available electronically at http://www.epa.gov/iris/subst/0276.htm
.

    \59\ International Agency for Research on Cancer, IARC
monographs on the evaluation of carcinogenic risk of chemicals to
humans, Volume 29, Some industrial chemicals and dyestuffs,
International Agency for Research on Cancer, World Health
Organization, Lyon, France, p. 345-389, 1982.
    \60\ Irons, R.D.; Stillman, W.S.; Colagiovanni, D.B.; Henry,
V.A. (1992) Synergistic action of the benzene metabolite
hydroquinone on myelopoietic stimulating activity of granulocyte/
macrophage colony-stimulating factor in vitro, Proc. Natl. Acad.
Sci. 89:3691-3695.
    \61\ Aksoy, M. (1989). Hematotoxicity and carcinogenicity of
benzene. Environ. Health Perspect. 82:193-197.
    \62\ Goldstein, B.D. (1988). Benzene toxicity. Occupational
medicine. State of the Art Reviews. 3:541-554.
    \63\ Rothman, N., G.L. Li, M. Dosemeci, W.E. Bechtold, G.E.
Marti, Y.Z. Wang, M. Linet, L.Q. Xi, W. Lu, M.T. Smith, N. Titenko-
Holland, L.P. Zhang, W. Blot, S.N. Yin, and R.B. Hayes (1996)
Hematotoxicity among Chinese workers heavily exposed to benzene. Am.
J. Ind. Med. 29:236-246.
    \64\ U.S. EPA 2002 Toxicological Review of Benzene (Noncancer
Effects). Environmental Protection Agency, Integrated Risk
Information System (IRIS), Research and Development, National Center
for Environmental Assessment, Washington, DC. This material is
available electronically at http://www.epa.gov/iris/subst/0276.htm.

    \65\ Qu, O.; Shore, R.; Li, G.; Jin, X.; Chen, C.L.; Cohen, B.;
Melikian, A.; Eastmond, D.; Rappaport, S.; Li, H.; Rupa, D.;
Suramaya, R.; Songnian, W.; Huifant, Y.; Meng, M.; Winnik, M.; Kwok,
E.; Li, Y.; Mu, R.; Xu, B.; Zhang, X.; Li, K. (2003). HEI Report
115, Validation & Evaluation of Biomarkers in Workers Exposed to
Benzene in China.
    \66\ Qu, Q., R. Shore, G. Li, X. Jin, L.C. Chen, B. Cohen, et
al. (2002). Hematological changes among Chinese workers with a broad
range of benzene exposures. Am. J. Industr. Med. 42: 275-285.
    \67\ Lan, Qing, Zhang, L., Li, G., Vermeulen, R., et al. (2004).
Hematotoxically in Workers Exposed to Low Levels of Benzene. Science
306: 1774-1776.
    \68\ Turtletaub, K.W. and Mani, C. (2003). Benzene metabolism in
rodents at doses relevant to human exposure from Urban Air. Research
Reports Health Effect Inst. Report No.113.
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    1,3-Butadiene: EPA has characterized 1,3-butadiene as carcinogenic
to humans by inhalation.69 70 The specific mechanisms of
1,3-butadiene-induced carcinogenesis are unknown. However, it is
virtually certain that the carcinogenic effects are mediated by
genotoxic metabolites of 1,3-butadiene. Animal data suggest that
females may be more sensitive than males for cancer effects; while
there are insufficient data in humans from which to draw conclusions
about sensitive subpopulations. 1,3-Butadiene also causes a variety of
reproductive and developmental effects in mice; no human data on these
effects are available. The most sensitive effect was ovarian atrophy
observed in a lifetime bioassay of female mice.\71\
    Formaldehyde: Since 1987, EPA has classified formaldehyde as a
probable human carcinogen based on evidence in humans and in rats,
mice, hamsters, and monkeys.\72\ EPA is currently reviewing recently
published epidemiological data. For instance, recently released
research conducted by the National Cancer Institute (NCI) found an
increased risk of nasopharyngeal cancer and lymphohematopoietic
malignancies such as leukemia among workers exposed to
formaldehyde.73 74 NCI is currently performing an update of
these studies. A recent National Institute of Occupational Safety and
Health (NIOSH) study of garment workers also found increased risk of
death due to leukemia among workers exposed to formaldehyde.\75\ Based
on the developments of the last decade, in 2004, the working group of
the International Agency for Research on Cancer (IARC) concluded that
formaldehyde is carcinogenic to humans (Group 1), on the basis of
sufficient evidence in humans and sufficient evidence in experimental
animals--a higher classification than previous IARC evaluations.
---------------------------------------------------------------------------

    \69\ U.S. EPA. 2002. Health Assessment of 1,3-Butadiene. Office
of Research and Development, National Center for Environmental
Assessment, Washington Office, Washington, DC. Report No. EPA600-P-
98-001F. This document is available electronically at http://www.epa.gov/iris/supdocs/buta-sup.pdf
.

    \70\ U.S. EPA. 2002. ``Full IRIS Summary for 1,3-butadiene
(CASRN 106-99-0)'' Environmental Protection Agency, Integrated Risk
Information System (IRIS), Research and Development, National Center
for Environmental Assessment, Washington, DC. http://www.epa.gov/iris/subst/0139.htm
.

    \71\ Bevan, C.; Stadler, J.C.; Elliot, G.S.; et al. (1996)
Subchronic toxicity of 4-vinylcyclohexene in rats and mice by
inhalation. Fundam. Appl. Toxicol. 32:1-10.
    \72\ U.S. EPA (1987). Assessment of Health Risks to Garment
Workers and Certain Home Residents from Exposure to Formaldehyde,
Office of Pesticides and Toxic Substances, April 1987.
    \73\ Hauptmann, M.; Lubin, J.H.; Stewart, P.A.; Hayes, R.B.;
Blair, A. 2003. Mortality from lymphohematopoietic malignancies
among workers in formaldehyde industries. Journal of the National
Cancer Institute 95: 1615-1623.
    \74\ Hauptmann, M..; Lubin, J.H.; Stewart, P.A.; Hayes, R.B.;
Blair, A. 2004. Mortality from solid cancers among workers in
formaldehyde industries. American Journal of Epidemiology 159: 1117-
1130.
    \75\ Pinkerton, L.E. 2004. Mortality among a cohort of garment
workers exposed to formaldehyde: an update. Occup. Environ. Med. 61:
193-200.
---------------------------------------------------------------------------

    Formaldehyde exposure also causes a range of noncancer health
effects, including irritation of the eyes (tearing of the eyes and
increased blinking) and mucous membranes.
    Acetaldehyde: Acetaldehyde is classified in EPA's IRIS database as
a probable human carcinogen, based on nasal tumors in rats, and is
considered toxic by the inhalation, oral, and intravenous routes.\76\
The primary acute effect of exposure to acetaldehyde vapors is
irritation of the eyes, skin, and respiratory tract.\77\ The agency is
currently conducting a reassessment of the health hazards from
inhalation exposure to acetaldehyde.
---------------------------------------------------------------------------

    \76\ U.S. EPA. 1988. Integrated Risk Information System File of
Acetaldehyde. Research and Development, National Center for
Environmental Assessment, Washington, DC. This material is available
electronically at http://www.epa.gov/iris/subst/0290.htm.

    \77\ U.S. EPA. 1988. Integrated Risk Information System File of
Acetaldehyde. Research and Development, National Center for
Environmental Assessment, Washington, DC. This material is available
electronically at http://www.epa.gov/iris/subst/0290.htm.

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

    Acrolein: Acrolein is intensely irritating to humans when inhaled,
with acute exposure resulting in upper respiratory tract irritation and
congestion. EPA determined in 2003 using the 1999 draft cancer
guidelines that the human carcinogenic potential of acrolein could not
be determined because the available data were inadequate. No
information was

available on the carcinogenic effects of acrolein in humans and the
animal data provided inadequate evidence of carcinogenicity.\78\
---------------------------------------------------------------------------

    \78\ U.S. EPA. 2003. Integrated Risk Information System File of
Acrolein. Research and Development, National Center for
Environmental Assessment, Washington, DC. This material is available
electronically at http://www.epa.gov/iris/subst/0364.htm.

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

    Polycyclic Organic Matter (POM): POM is generally defined as a
large class of organic compounds which have multiple benzene rings and
a boiling point greater than 100 degrees Celsius. Many of the compounds
included in the class of compounds known as POM are classified by EPA
as probable human carcinogens based on animal data. One of these
compounds, naphthalene, is discussed separately below.
    Recent studies have found that maternal exposures to PAHs in a
population of pregnant women were associated with several adverse birth
outcomes, including low birth weight and reduced length at birth, as
well as impaired cognitive development at age three.79 80
EPA has not yet evaluated these recent studies.
---------------------------------------------------------------------------

    \79\ Perera, F.P.; Rauh, V.; Tsai, W-Y.; et al. (2002) Effect of
transplacental exposure to environmental pollutants on birth
outcomes in a multiethnic population. Environ Health Perspect. 111:
201-205.
    \80\ Perera, F.P.; Rauh, V.; Whyatt, R.M.; Tsai, W.Y.; Tang, D.;
Diaz, D.; Hoepner, L.; Barr, D.; Tu, Y.H.; Camann, D.; Kinney, P.
(2006) Effect of prenatal exposure to airborne polycyclic aromatic
hydrocarbons on neurodevelopment in the first 3 years of life among
inner-city children. Environ Health Perspect 114: 1287-1292.
---------------------------------------------------------------------------

    Naphthalene: Naphthalene is found in small quantities in gasoline
and diesel fuels but is primarily a product of combustion. EPA recently
released an external review draft of a reassessment of the inhalation
carcinogenicity of naphthalene.\81\ The draft reassessment recently
completed external peer review.\82\ Based on external peer review
comments, additional analyses are being considered. California EPA has
released a new risk assessment for naphthalene, and the IARC has
reevaluated naphthalene and re-classified it as Group 2B: possibly
carcinogenic to humans.\83\ Naphthalene also causes a number of chronic
non-cancer effects in animals, including abnormal cell changes and
growth in respiratory and nasal tissues.\84\
---------------------------------------------------------------------------

    \81\ U.S. EPA. 2004. Toxicological Review of Naphthalene
(Reassessment of the Inhalation Cancer Risk), Environmental
Protection Agency, Integrated Risk Information System, Research and
Development, National Center for Environmental Assessment,
Washington, DC. This material is available electronically at http://www.epa.gov/iris/subst/0436.htm
.

    \82\ Oak Ridge Institute for Science and Education. (2004).
External Peer Review for the IRIS Reassessment of the Inhalation
Carcinogenicity of Naphthalene. August 2004. http://cfpub2.epa.gov/ncea/cfm/recordisplay.cfm?deid=86019
.

    \83\ International Agency for Research on Cancer (IARC). (2002).
Monographs on the Evaluation of the Carcinogenic Risk of Chemicals
for Humans. Vol. 82. Lyon, France.
    \84\ U.S. EPA. 1998. Toxicological Review of Naphthalene,
Environmental Protection Agency, Integrated Risk Information System,
Research and Development, National Center for Environmental
Assessment, Washington, DC. This material is available
electronically at http://www.epa.gov/iris/subst/0436.htm.

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    In addition to reducing substantial amounts of NOX and
PM2.5 emissions from locomotive and marine diesel engines,
the standards being proposed today would also reduce air toxics emitted
from these engines. This will help mitigate some of the adverse health
effects associated with operation of these engines.

C. Other Environmental Effects

    There is a number of public welfare effects associated with the
presence of ozone and PM2.5 in the ambient air. In this
section we discuss 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.\85\ Visibility impairment manifests in
two principal ways: as local visibility impairment and as regional
haze.\86\ 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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    \85\ National Research Council, 1993. Protecting Visibility in
National Parks and Wilderness Areas. National Academy of Sciences
Committee on Haze in National Parks and Wilderness Areas. National
Academy Press, Washington, DC. This document is available in Docket
EPA-HQ-OAR-2005-0036. This book can be viewed on the National
Academy Press Web site at http://www.nap.edu/books/0309048443/html/.

    \86\ See discussion in U.S. EPA, National Ambient Air Quality
Standards for Particulate Matter; Proposed Rule; January 17, 2006,
Vol 71 p 2676. This information is available electronically at
http://epa.gov/fedrgstr/EPA-AIR/2006/January/Day-17/a177.pdf.

    \87\ 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-2005-0036.
    \88\ 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-2005-0036.
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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 as well
as the 2005 PM Staff Paper.87 88

    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 38680-81, July 18, 1997).\89\ 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.\90\
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    \89\ 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.
    \90\ As mentioned above, the EPA has recently proposed to amend
the PM NAAQS (71 FR 2620, Jan. 17, 2006). The proposal would set the
secondary NAAQS equal to the primary standards for both
PM2.5 and PM10-2.5. EPA
also is taking comment on whether to set a separate PM2.5
standard, designed to address visibility (principally in urban
areas), on potential levels for that standard within a range of 20
to 30 [mu]g/m\3\, and on averaging times for the standard within a
range of four to eight daylight hours.
---------------------------------------------------------------------------

    Locomotives and marine engines contribute to visibility concerns in
these areas through their primary PM2.5 emissions and their
NOX emissions which contribute to the formation of secondary
PM2.5.
Current Visibility Impairment
    Recently designated PM2.5 nonattainment areas indicate
that, as of March 2, 2006, 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.\91\ \92\ The mandatory
federal class I areas are listed in Chapter 2 of the draft RIA for this
action. The areas that have design values above the 1997
PM2.5 NAAQS are also listed in Chapter 2 of the draft RIA
for this action.
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    \91\ US 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 also available on the Web at: http://www.epa.gov/pmdesignations/.

    \92\ US EPA. Regional Haze Regulations, July 1, 1999. (64 FR
35714, July 1, 1999).
---------------------------------------------------------------------------

Future Visibility Impairment

    Recent modeling for this proposed rule was used to project
visibility conditions in the 116 mandatory class I federal areas across
the U.S. in 2020 and 2030 resulting from the proposed locomotive and
marine diesel engine standards. The results suggest that improvement in
visibility would occur in all class I federal areas although areas
would continue to have annual average deciview levels above background
in 2020 and 2030. Table II-2 groups class I federal areas by regions
and illustrates that regardless of geographic area, reductions in
PM2.5 emissions from this rule would benefit visibility in
each region of the U.S. in mandatory class I federal areas.

          Table II-2.--SUmmary of Modeled 2030 Visibility Conditions in Mandatory Class I Federal Areas
                                            [Annual average deciview]
----------------------------------------------------------------------------------------------------------------
                                                        Predicted 2030
                                                          visibility        Predicted 2030     Change in annual
                       Region                         baseline  w/o rule    visibility with    average deciview
                                                             rule            rule  control
----------------------------------------------------------------------------------------------------------------
                                                     Eastern
----------------------------------------------------------------------------------------------------------------
Southeast...........................................               17.52               17.45                 .07
Northeast/Midwest...................................               14.85               14.80                 .05
----------------------------------------------------------------------------------------------------------------
                                                     Western
----------------------------------------------------------------------------------------------------------------
Southwest...........................................                9.36                9.32                 .04
West (CA-NV-UT).....................................                9.99                9.92                 .07
Rocky Mountain......................................                8.37                8.33                 .04
Northwest...........................................                9.11                9.05                 .06
National Class I Area Average.......................               10.97               10.91                 .06
----------------------------------------------------------------------------------------------------------------
Notes:
(a) Background visibility conditions differ by regions: Eastern natural background is 9.5 deciview (or visual
  range of 150 kilometers) and the West natural background is 5.3 deciview (or visual range of 230 kilometers).
(b) The results average visibility conditions for mandatory Class I Federal areas in the regions.
(c) The results illustrate the type of visibility improvements for the primary control options. The proposal
  differs based on updated information; however, we believe that the net results would approximate future PM
  emissions.

(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 Criteria
Document presents more detailed information on ozone effects on
vegetation and ecosystems.
    As discussed above, locomotive and marine diesel engine emissions
of NOX contribute to ozone and therefore the proposed
NOX standards will 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 standards would help reduce acid
deposition, thereby helping to reduce acidity levels in lakes and
streams throughout the country and helping 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 this rule will
differ across different areas.
(4) Eutrophication and Nitrification
    The NOX standards proposed in this action will 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 fresh water and
estuarine resources for human uses.\93\
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    \93\ Deposition of Air Pollutants to the Great Waters, Third
Report to Congress, June 2000, EPA-453/R-00-005. This document can
be found in Docket No. OAR-2002-0030, Document No. OAR-2002-0030-
0025. 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 fish kills 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.\94\
---------------------------------------------------------------------------

    \94\ 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.
---------------------------------------------------------------------------

    (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.\95\ 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.
---------------------------------------------------------------------------

    \95\ 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-2005-0036.
---------------------------------------------------------------------------

    The PM2.5 standards proposed in this action will help
reduce the airborne particles that contribute to materials damage and
soiling.

D. Other Criteria Pollutants Affected by This NPRM

    Locomotive and marine diesel engines account for about 1 percent of
the mobile sources carbon monoxide (CO) inventory. Carbon monoxide (CO)
is a colorless, odorless gas produced through the incomplete combustion
of carbon-based fuels. The current primary NAAQS for CO are 35 ppm for
the 1-hour average and 9 ppm for the 8-hour average. These values are
not to be exceeded more than once per year. As of October 2006, there
are 15.5 million people living in 6 areas (10 counties) that are
designated as nonattainment for CO.
    Carbon monoxide enters the bloodstream through the lungs, forming
carboxyhemoglobin and reducing the delivery of oxygen to the body's
organs and tissues. The health threat from CO is most serious for those
who suffer from cardiovascular disease, particularly those with angina
or peripheral vascular disease. Healthy individuals also are affected,
but only at higher CO levels. Exposure to elevated CO levels is
associated with impairment of visual perception, work capacity, manual
dexterity, learning ability and performance of complex tasks. Carbon
monoxide also contributes to ozone nonattainment since carbon monoxide
reacts photochemically in the atmosphere to form ozone. Additional
information on CO related health effects

can be found in the Air Quality Criteria for Carbon Monoxide.\96\
---------------------------------------------------------------------------

    \96\ U.S. EPA (2000). Air Quality Criteria for Carbon Monoxide,
EPA/600/P-99/001F. This document is available in Docket EPA-HQ-OAR-
2004-0008.
---------------------------------------------------------------------------

E. Emissions From Locomotive and Marine Diesel Engines

(1) Overview
    The engine standards being proposed in this rule would affect
emissions of particulate matter (PM2.5), oxides of nitrogen
(NOX), volatile organic compounds (VOCs), and air toxics.
Carbon monoxide is not specifically targeted in this proposal although
the technologies applied to control these other pollutants are expected
to also reduce CO emissions.
    Locomotive and marine diesel engine emissions are expected to
continue to be a significant part of the mobile source emissions
inventory both nationally and in ozone and PM2.5
nonattainment areas in the coming years. In the absence of new
emissions standards, we expect overall emissions from these engines to
decrease modestly over the next ten to fifteen years than remain
relatively flat through 2025 due to existing regulations such as lower
fuel sulfur requirements, the phase in of locomotive and marine diesel
Tier 1 and Tier 2 engine standards, and the Tier 0 locomotive
remanufacturing requirements. Beginning thereafter, emission
inventories from these engines would once again begin increasing due to
growth in the locomotive and marine sectors. Under today's proposed
standards, by 2030, annual NOX emissions from these engines
would be reduced by 765,000 tons, PM2.5 emissions by 28,000
tons, and VOC emissions by 42,000 tons.
    In this section we first present base case emissions inventory
contributions for locomotive and marine diesel engines and other mobile
sources assuming no further emission controls beyond those already in
place. The 2001 inventory numbers were developed and used as an input
into our air quality modeling. Individual sub-sections which follow
discuss PM2.5, NOX, and VOC pollutants, in terms
of expected emission reductions associated with the proposed standards.
The tables and figures illustrate the Agency's analysis of current and
future emissions contributions from locomotive and marine diesel
engines.
(2) Estimated Inventory Contribution
    Locomotive and marine diesel engine emissions contribute to
nationwide PM, NOX, VOC, CO, and air toxics inventories. Our
current baseline and future year estimates for NOX and
PM2.5 inventories (50-state) are set out in Tables II-3 and
II-4. Based on our analysis undertaken for this rulemaking, we estimate
that in 2001 locomotives and marine diesel engines contributed almost
60,000 tons (18 percent) to the national mobile source diesel
PM2.5 inventory and about 2.0 million tons (16 percent) to
the mobile source NOX inventory. In 2030, absent the
standards proposed today, these engines would contribute about 50,000
tons (65 percent) to the mobile source diesel PM2.5
inventory and almost 1.6 million tons (35 percent) to the mobile source
NOX inventory.
    The national locomotives and marine diesel engine PM2.5
and NOX inventories in 2030 would be roughly twice as large
as the combined PM2.5 and NOX inventories from
on-highway diesel and land-based nonroad diesel engines. In absolute
terms--locomotives and marine diesel engines, in 2030, would annually
emit 22,000 more tons of PM2.5 and 890,000 more tons of
NOX than all highway and nonroad diesels combined. This
occurs because EPA has already taken steps to bring engine emissions
from both on-highway and nonroad diesels to near-zero levels, while
locomotives and marine diesel engines continue to meet relatively
modest emission requirements. Table II-4 shows that in 2001 the land-
based nonroad diesel category contributed about 160,000 tons of
PM2.5 emissions and by 2030 they drop to under 18,000 tons.
Likewise, in 2001, annual PM2.5 emissions from highway
diesel engines totaled about 110,000 tons falling in 2030 to about
10,000 tons. Table II-3 shows a similar downward trend occurring for
annual NOX emissions. In 2001, NOX emissions from
highway diesel engines' amounted to over 3.7 million tons but by 2030
they fall to about 260,000 tons. Finally, land-based nonroad diesels in
2001 emitted over 1.5 million tons of NOX but by 2030 these
emissions drop to approximately 430,000 tons.
    Marine diesel engine and locomotive inventories were developed
using multiple methodologies. Chapter 3 of the draft RIA provides a
detailed explanation of our approach. In summary, the quality of data
available for locomotive inventories made it possible to develop more
detailed estimates of fleet composition and emission rates than we have
previously done. Locomotive emissions were calculated based on
estimated current and projected fuel consumption rates. Emissions were
calculated separately for the following locomotive categories: line-
haul locomotives in large railroads, switching locomotives in large
railroads (including Class II/III switch railroads owned by Class I
railroads), other line-haul locomotives (i.e., local and regional
railroads), other switch/terminal locomotives, and passenger
locomotives. Our inventories for marine diesel engines were created
using the inventory for marine diesel engines up to 30 liters per
cylinder displacement including recreational, commercial, and auxiliary
applications was developed by using a methodology based on engine
population, hours of use, average engine loads, and in-use emissions
factors.

                                               Table II-3.--Nationwide Annual NOX Baseline Emission Levels
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                2001                                         2030
                                                                ----------------------------------------------------------------------------------------
                                                                                Percent
                            Category                                                                                of
                                                                 NOX short tons    Percent of      Percent of          NOX         Percent of     total
                                                                                mobile source       total                       mobile source   short
                                                                                tons
--------------------------------------------------------------------------------------------------------------------------------------------------------
Locomotive.....................................................       1,118,786             9.0             5.1         854,226            19.0   8.1
Recreational Marine Diesel.....................................          40,437             0.3             0.2          48,155             1.1   0.5
Commercial Marine (C1 & C2)....................................         833,963             6.7             3.8         679,973            15.1   6.4
Land-Based Nonroad Diesel......................................       1,548,236            12.5             7.1         434,466             9.7   4.1
Commercial Marine (C3)*........................................         224,100             1.8             1.0         531,641            11.8   5.0
Small Nonroad SI...............................................         100,319             0.8             0.5         114,287             2.5   1.1
Recreational Marine SI.........................................          42,252             0.3             0.2          92,188             2.1   0.9
SI Recreational Vehicles.......................................           5,488             0.0             0.0          20,136             0.4   0.2
Large Nonroad SI (>25hp).......................................         321,098             2.6             1.5          46,253             1.0   0.4

Aircraft.......................................................          83,764             0.7             0.4         118,740             2.6   1.1
Total Off Highway..............................................       4,318,443            34.8            19.8       2,940,066            65.5  27.7
Highway Diesel.................................................       3,750,886            30.2            17.2         260,915             5.8   2.5
Highway non-diesel.............................................       4,354,430            35.0            20.0       1,289,780            28.7  12.2
Total Highway..................................................       8,105,316            65.2            37.2       1,550,695            34.5  14.6
Total Diesel (distillate) Mobile...............................       7,292,308            58.7            33.5       2,277,735            50.7  21.5
Total Mobile Sources...........................................      12,423,758             100            57.0       4,490,761             100  42.4
Stationary Point and Area Sources..............................       9,355,659               -            43.0       6,111,866               -  57.6
Total Man-Made Sources.........................................      21,779,418               -             100      10,602,627               -   100
--------------------------------------------------------------------------------------------------------------------------------------------------------
* This category includes emissions from Category 3 (C3) propulsion engines and C2/3 auxiliary engines used on ocean-going vessels.

                                              Table II-4.--Nationwide Annual PM2.5 Baseline Emission Levels
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              2001                                             2030
                                                       -------------------------------------------------------------------------------------------------
                       Category                           PM2.5 short      Percent of      Percent of      PM2.5 short      Percent of      Percent of
                                                             tons        diesel mobile    mobile source       tons        diesel mobile    mobile source
--------------------------------------------------------------------------------------------------------------------------------------------------------
Locomotive............................................          29,660              8.9            6.36          25,109             32.2           10.01
Recreational Marine Diesel............................           1,096              0.3            0.24           1,141              1.5            0.45
Commercial Marine (C1 & C2)...........................          28,728              8.6            6.16          23,758             30.5            9.47
Land-Based Nonroad Diesel.............................         164,180             49.2           35.2           17,934             23.0            7.1
Commercial Marine (C3)................................          20,023  ...............            4.30          52,682  ...............           20.99
Small Nonroad SI......................................          25,575  ...............            5.5           35,761  ...............           14.3
Recreational Marine SI................................          17,101  ...............            3.7            6,378  ...............            2.5
SI Recreational Vehicles..............................          12,301  ...............            2.6            9,953  ...............            4.0
Large Non road SI (>25hp).............................           1,610  ...............            0.3            2,844  ...............            1.1
Aircraft..............................................           5,664  ...............            1.22           8,569  ...............            3.41
Total Off Highway.....................................         305,939  ...............           65.6          184,129  ...............           73.4
Highway Diesel........................................         109,952             33.0           23.6           10,072             12.9            4.0
Highway non-diesel....................................          50,277  ...............           10.8           56,734  ...............           22.6
Total Highway.........................................         160,229  ...............           34.4           66,806  ...............           26.6
Total Diesel (distillate) Mobile......................         333,618            100             71.6           78,014            100             31.1
Total Mobile Sources..................................         466,168  ...............          100            250,934  ...............          100
Stationary Point and Area Sources Diesel..............           3,189  ...............  ..............           2,865  ...............  ..............
Stationary Point and Areas Sources non-diesel.........       1,963,264  ...............  ..............       1,817,722  ...............  ..............
Total Stationary Point and Area Sources...............       1,966,453  ...............  ..............       1,820,587  ...............  ..............
    Total Man-Made Sources............................       2,432,621  ...............  ..............       2,071,521  ...............  ..............
--------------------------------------------------------------------------------------------------------------------------------------------------------

(3) PM2.5 Emission Reductions
    In 2001 annual emissions from locomotive and marine diesel engines
totaled about 60,000 tons. Table II-4 shows the distribution of these
PM2.5 emissions: locomotives contributed about 30,000 tons,
recreational marine diesel roughly 1,000 tons, and commercial marine
diesel (C1 and C2) 29,000 tons. Due to current standards, annual
PM2.5 emissions from these engines drop to 50,000 tons in
2030 with roughly proportional emission reductions occurring in both
the locomotive and commercial marine diesel categories while the
recreational marine diesel category experiences a slight increase in
PM2.5 emissions. Both Tables II-5 and Figure II-4 show
PM2.5 emissions nearly flat through 2030 before beginning to
rise again due to growth in these sectors.
    Table II-5 shows how the proposed rule would begin reducing
PM2.5 emissions from the current national inventory baseline
starting in 2015 when annual reductions of 7,000 tons would occur. By
2020 that number would grow to 15,000 tons of PM2.5, by 2030
to 28,000 annual tons, and reductions would continue to grow through
2040 to about 39,000 tons of PM2.5 annually.

        Table II-5.--Locomotive and Marine Diesel PM2.5 Emissions
                            [Short tons/year]
------------------------------------------------------------------------
                                 2015       2020       2030       2040
------------------------------------------------------------------------
Without Proposed Rule.......     51,000     50,000     50,000     54,000
With Proposed Rule..........     44,000     35,000     22,000     15,000
Reductions From Proposed          7,000     15,000     28,000     39,000
 Rule.......................
------------------------------------------------------------------------

[GRAPHIC] [TIFF OMITTED] TP03AP07.003

    Although this proposed rule results in large nationwide
PM2.5 inventory reductions, it would also help urban areas
that have significant locomotive and marine diesel engine emissions in
their inventories. Table II-6 shows the percent these engines
contribute to the mobile source diesel PM2.5 inventory in a
variety of urban areas in 2001 and 2030. In 2001, a number of
metropolitan areas saw locomotives and marine diesel engines contribute
a much larger share to their local inventories than the national
average including Houston (42 percent), Los Angeles (32 percent), and
Baltimore (23 percent). In 2030, each of these metropolitan areas would
continue to see locomotive and marine diesel engines comprise a larger
portion of their mobile source diesel PM2.5 inventory than
the national average as would other communities including Cleveland (72
percent), Chicago (70 percent) and Chattanooga (70 percent).

 Table II-6.--Locomotive and Marine Diesel Contribution to Mobile Source
Diesel PM2.5 Inventories in Selected Metropolitan Areas in 2001 and 2030
------------------------------------------------------------------------
                                                       2001       2030
              Metropolitan area (MSA)                Percent    Percent
------------------------------------------------------------------------
National Average..................................         18         65
Los Angeles, CA...................................         32         73
Houston, TX.......................................         42         85
Chicago, IL.......................................         25         70
Philadelphia, PA..................................         20         64
Cleveland-Akron-Lorain, OH........................         26         72
St. Louis, MO.....................................         22         68
Seattle, WA.......................................         17         61
Kansas City, MO...................................         21         68
Baltimore, MD.....................................         23         68
Cincinnati, OH....................................         24         70
Boston, MA........................................          8         41
Huntington-Ashland WV-KY-OH.......................         53         91
New York, NY......................................          4         21
San Joaquin Valley, CA............................          9         39
Minneapolis-St. Paul, MN..........................         11         48
Atlanta, GA.......................................          6         30
Phoenix-Mesa, AZ..................................          5         27
Birmingham, AL....................................         17         58
Detroit, MI.......................................          5         26
Chattanooga, TN...................................         22         70
Indianapolis, IN..................................          5         30
------------------------------------------------------------------------

(4) NOX Emissions Reductions
    In 2001 annual emissions from locomotive and marine diesel engines
totaled about 2.0 million tons. Table II-3 shows the distribution of
these NOX emissions: locomotives contributed about 1.1
million tons, recreational marine diesel roughly 40,000 tons, and
commercial marine diesel (C1 and C2) 834,000 tons. Due to current
standards, annual NOX emission from these engines drop to
1.6 million tons in 2030 with roughly proportional emission reductions
occurring in both the locomotive and commercial marine diesel
categories while the recreational marine diesel category experiences an
increase in PM2.5 emissions. Both Table II-7 and Figure II-5
show NOX

emissions remaining nearly flat through 2030 before beginning to rise
again due to growth in these sectors.
    Table II-7 shows how the proposed rule would begin reducing
NOX emissions from the current national inventory baseline
starting in 2015 when annual reductions of 84,000 tons would occur. By
2020 that number would grow to 293,000 tons of NOX, by 2030
to 765,000 annual tons, and reductions would continue to grow through
2040 to about 1.1 million tons of NOX annually.
    These numbers are comparable to emission reductions projected in
2030 for our already established nonroad Tier 4 program. Table II-8
provides the 2030 NOX emission reductions (and PM
reductions) for this proposed rule compared to the Heavy-Duty Highway
rule and Nonroad Tier 4 rule. The 2030 NOX reductions of
about 740,000 tons for the Nonroad Tier 4 are similar to those from
this proposed rule.

                             Table II-7.--Locomotive and Marine Diesel NOX Emissions
                                                [Short tons/year]
----------------------------------------------------------------------------------------------------------------
                                                              2015          2020          2030          2040
----------------------------------------------------------------------------------------------------------------
Without Proposed Rule...................................     1,633,000     1,582,000     1,582,000     1,703,000
With Proposed Rule......................................     1,549,000     1,289,000       817,000       579,000
Reductions From Proposed Rule...........................        84,000       293,000       765,000     1,124,000
----------------------------------------------------------------------------------------------------------------

   Table II-8.--Projected 2030 Emissions Reductions From Recent Mobile
                              Source Rules
                              [Short tons]
------------------------------------------------------------------------
                       Rule                            NOX       PM2.5
------------------------------------------------------------------------
Proposed Locomotive and Marine....................    765,000     28,000
Nonroad Tier 4....................................    738,000    129,000
Heavy-Duty Highway................................  2,600,000    109,000
------------------------------------------------------------------------

                                                               [GRAPHIC] [TIFF OMITTED] TP03AP07.004

    Although this proposed rule results in large nationwide
NOX inventory reductions, it would also help urban areas
that have significant concentrations of locomotive and marine diesel
engines in their inventories. Table II-9 shows the percent these
engines contribute to the mobile source diesel NOX inventory
in a variety of urban areas in 2001 and 2030. In 2001, a number of
metropolitan areas saw locomotives and marine diesel engines contribute
a much larger share to their local inventories than the national
average including Houston (32 percent), Kansas City (20 percent), and
Los Angeles (19 percent). In 2030, each of these metropolitan areas
would continue to see locomotive and marine diesel engines comprise a
larger portion of their mobile source diesel PM2.5 inventory
than the national average as would other communities including
Birmingham (43 percent), Chicago (42 percent) and Chattanooga (40
percent).

 Table II-9.--Locomotive and Marine Diesel Engine Contribution to Mobile
 Source NOX Inventories in Selected Metropolitan Areas in 2001 and 2030
------------------------------------------------------------------------
                                                       2001       2030
             Metropolitan areas (MSA)                Percent    Percent
------------------------------------------------------------------------
National Average..................................         16         35
Los Angeles, CA...................................         19         38
Houston, TX.......................................         32         45
Chicago, IL.......................................         20         42
Philadelphia, PA..................................         14         19
Cleveland-Akron-Lorain, OH........................         19         40
New York, NY......................................          5          8
St. Louis, MO.....................................         16         37
Seattle, WA.......................................         14         31
Kansas City, MO...................................         20         44
Cincinnati, OH....................................         18         39
Huntington-Ashland, WV-KY-OH......................         39         37
Boston, MA........................................          7         11
San Joaquin Valley, CA............................          9         26
Minneapolis-St. Paul, MN..........................          9         20
Atlanta, GA.......................................          5         13
Birmingham, AL....................................         17         43
Baltimore, MD.....................................          8         10
Phoenix-Mesa, AZ..................................          6         15
Detroit, MI.......................................          3          9
Chattanooga, TN...................................         16         40
Indianapolis, IN..................................          5         13
------------------------------------------------------------------------

(5) Volatile Organic Compounds Emissions Reductions
    Emissions of volatile organic compounds (VOCs) from locomotive and
marine diesel engines based on a 50-state inventory are shown in Table
II-10, along with the estimates of the reductions in 2015, 2020, 2030
and 2040 we expect would result from the VOC exhaust emission standard
in our proposed rule. In 2015 15,000 tons of VOCs would be reduced and
by 2020 reductions would almost double to 27,000 tons annually from
these engines. Over the next ten years annual reductions from
controlled locomotive and marine diesel engines would produce annual
VOC reductions of 42,000 tons in 2030 and 54,000 tons in 2040.
    Figure II-6 shows our estimate of VOC emissions between 2005 and
2040 both with and without the proposed standards of this rule. We
estimate that VOC emissions from locomotive and marine diesel engines
would be reduced by 60 percent by 2030 and by 70 percent in 2040.

        Table II-10.--Locomotive and Marine Diesel VOC Emissions
                           [ short tons/year]
------------------------------------------------------------------------
                                 2015       2020       2030       2040
------------------------------------------------------------------------
Without Proposed Rule.......     72,000     71,000     72,000     78,000
With Proposed Rule..........     57,000     44,000     30,000     24,000
Reductions From Proposed         15,000     27,000     42,000     54,000
 Rule.......................
------------------------------------------------------------------------

                                                               [GRAPHIC] [TIFF OMITTED] TP03AP07.005

III. Emission Standards

    This section details the emission standards, implementation dates,
and other major requirements of the proposed program. Following brief
summaries of the types of locomotives and marine engines covered and of
the existing standards, we describe the proposed provisions for
setting:
     Tier 3 and Tier 4 standards for newly-built locomotives,
     Standards for remanufactured Tier 0, 1, and 2 locomotives,

     Standards and other provisions for diesel switch
locomotives,
     Requirements to reduce idling locomotive emissions, as
well as possible ways to encourage emission reductions through the
optimization of multi-locomotive teams (consists), and
     Tier 3 and Tier 4 standards for newly-built marine diesel
engines.
    As discussed in sections I.A(2) and VII.A(2), we are also
soliciting comment on setting standards for remanufactured marine
diesel engines.
    A detailed discussion of the technological feasibility of the
proposed standards follows the description of the proposed program. The
section concludes with a discussion of considerations and activities
surrounding emissions from large Category 3 engines used on ocean-going
vessels, although we are not proposing provisions for these engines in
this rulemaking.
    To ensure that the benefits of the standards are realized in-use
and throughout the useful life of these engines, and to incorporate
lessons learned over the last few years from the existing test and
compliance program, we are also proposing revised test procedures and
related certification requirements. In addition, we are proposing to
continue the averaging, banking, and trading (ABT) emissions credits
provisions to demonstrate compliance with the standards. These
provisions are described further in section IV.

A. What Locomotives and Marine Engines Are Covered?

    The regulations being proposed would affect locomotives currently
regulated under part 92 and marine diesel engines and vessels currently
regulated under parts 89 and 94, as described below.\97\
---------------------------------------------------------------------------

    \97\ All of the regulatory parts referenced in this preamble are
parts in Title 40 of the Code of Federal Regulations, unless
otherwise noted.
---------------------------------------------------------------------------

    With some exceptions, the regulations apply for all locomotives
that operate extensively within the United States. See section IV.B for
a discussion of the exemption for locomotives that are used only
incidentally within the U.S. The exceptions include historic steam-
powered locomotives and locomotives powered solely by an external
source of electricity. In addition, the regulations generally do not
apply to existing locomotives owned by railroads that are classified as
small businesses.\98\ Furthermore, engines used in locomotive-type
vehicles with less than 750 kW (1006 hp) total power (used primarily
for railway maintenance), engines used only for hotel power (for
passenger railcar equipment), and engines that are used in self-
propelled passenger-carrying railcars, are excluded from these
regulations. The engines used in these smaller locomotive-type vehicles
are generally subject to the nonroad engine requirements of Parts 89
and 1039.
---------------------------------------------------------------------------

    \98\ This small business provision is limited to railroads that
are classified as small businesses by the Small Business
Administration (SBA). Many but not all Class II and III railroads
qualify as small businesses for this provision. See the 1998
locomotive rule (63 FR 18978, April 16, 1998) for a complete
discussion of the basis and application of this provision.
---------------------------------------------------------------------------

    There are currently three tiers of locomotive emission standards.
The Tier 0 standards apply only to locomotives originally manufactured
before 2002, the Tier 1 standards apply to new locomotives manufactured
in 2002-2004, and the Tier 2 standards apply to new locomotives
manufactured in 2005 and later. Under the existing regulations, the
applicability of the Tier 1 and Tier 2 standards is based on the date
of manufacture of the locomotive, rather than the engine. Thus, a newly
manufactured engine in 2005 that is used to repower a 1990 model year
locomotive would be subject to the Tier 0 emission standards, which are
also applicable to all other 1990 model year locomotives. As described
in section IV.B, we are proposing some changes to this approach.
    The marine diesel engines covered by this rule would include
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 gensets to large generators on ocean-going
vessels.\99\ Marine diesel engines are categorized both by per cylinder
displacement and by rated power. Consistent with our existing marine
diesel emission control program, the proposed standards would apply to
any marine diesel engine with per cylinder displacement below 30 liters
installed on a vessel flagged or registered in the United States.
According to our existing definitions, a marine engine is defined as an
engine that is installed or intended to be installed on a marine
vessel.
---------------------------------------------------------------------------

    \99\ Marine diesel engines at or above 30 l/cyl displacement are
not included in this program. See Section 3E, below.
---------------------------------------------------------------------------

    While marine diesel engines up to 37 kW (50 hp) are currently
covered by our nonroad Tier 1 and Tier 2 standards, they were not
included in the nonroad Tier 3 and Tier 4 programs. Instead, they are
covered in this rule, making this a comprehensive control strategy for
all marine diesel engines below 30 liters per cylinder displacement.
This is a very broad range of engines and they are grouped into several
categories for the existing standards, as described in detail in
Chapter 1 of the draft RIA.
    Consistent with our current marine diesel engine program, the
standards described in this proposal would apply to engines
manufactured for sale in the United States or imported into the United
States beginning with the effective date of the standards. Any engine
installed on a new vessel flagged or registered in the U.S. would be
required to meet the appropriate emission limits. Also consistent with
our current marine diesel engine program, the standards would also
apply to any engine installed for the first time in a marine vessel
flagged or registered in the U.S. after having been used in another
application subject to different emission standards. In other words, an
existing nonroad diesel engine would become a new marine diesel engine,
and subject to the marine diesel engine standards, when it is marinized
for use in a marine application.
    Our current marine diesel engine emission controls do not apply to
marine diesel engines on foreign vessels entering U.S. ports. At this
time we believe it is appropriate to postpone consideration of the
application of our national standards to engines on foreign vessels to
a future rulemaking that would consider controls for Category 3 engines
on ocean-going vessels. This will allow us consider the engines on
foreign vessels as an integrated system, to better evaluate the
regulatory options available for controlling their overall emission
contribution to U.S. ambient air quality.
    Nevertheless, we are soliciting comment on whether the emission
standards we are proposing in this action should apply to engines below
30 liters per cylinder displacement installed on foreign vessels
entering U.S. ports, and to no longer exclude these engines from the
emission standards under 40 CFR 94.1(b)(3). Commenters are also invited
to suggest when the standards should apply to foreign vessels. For
example, the standards could apply based on the date the engine is
built or, consistent with MARPOL Annex VI, the date the vessel is
built.

B. Existing EPA Standards

    NOX emission levels from newly-built locomotives have
been reduced over the past several years from unregulated levels of
over 13 g/bhp-hr (17 g/kW-hr) to the current Tier 2 standard level for
newly-built locomotives of 5.5 g/bhp-hr

(7.3 g/kW-hr)--a 60 percent reduction.\100\ PM reductions on the order
of 50 percent have also been achieved under a Tier 2 standard level of
0.20 g/bhp-hr (0.27 g/kW-hr). EPA emission standards for marine diesel
engines vary somewhat due to the ranges in size and application of
engines included; however Tier 2 levels for recreational and commercial
marine engines are generally comparable in stringency to those adopted
for locomotives, and are now in the process of phasing in over 2004-
2009. See Chapter 1 of the draft RIA for a complete listing of the
existing standards, including standards for remanufactured locomotives.
---------------------------------------------------------------------------

    \100\ Consistent with past EPA rulemakings, our regulations
generally express standards, power ratings, and other quantities in
international SI (metric) units--kW, g/kW-hr, etc. One exception to
this is Part 92 (locomotives), which for historical reasons
expresses standards in g/bhp-hr. This proposal retains these
established norms for locomotive and marine engine regulations.
However, in this preamble we have chosen to express standards in
units of g/bhp-hr, to provide a common frame of reference. Where
helpful for clarity, we have also included g/kW-hr standards in
parentheses. In any compliance questions that might arise from
differences in these due to, for example, rounding conventions, the
regulations themselves establish the applicable requirements.
---------------------------------------------------------------------------

    The Tier 2 emissions reductions have been achieved largely through
engine calibration optimization and engine hardware design changes
(such as improved fuel injectors and turbochargers, increased injection
pressure, intake air after-cooling, combustion chamber design, reduced
oil consumption and injection timing) Although these reductions in
locomotive and marine emissions are important, they only bring today's
cleanest locomotives and marine diesels to roughly the emissions levels
of new trucks in the early 1990's, on the basis of grams per unit of
work done.

C. What Standards Are We Proposing?

(1) Locomotive Standards
(a) Line-Haul Locomotives
    We are proposing new emission standards for newly-built and
remanufactured line-haul locomotives. Our proposed standards for newly-
built line-haul locomotives would be implemented in two tiers: First, a
new Tier 3 PM standard of 0.10 g/bhp-hr (0.13 g/kW-hr) taking effect in
2012, based on engine design improvements; second, new Tier 4 standards
of 0.03 g/bhp-hr (0.04 g/kW-hr) for PM, 0.14 g/bhp-hr (0.19 g/kW-hr)
for HC (both taking effect in 2015), and 1.3 g/bhp-hr (1.8 g/kW-hr) for
NOX (taking effect in 2017), based on the application of the
high-efficiency catalytic aftertreatment technologies now being
developed and introduced in the highway diesel sector. Our proposed
standards for remanufactured line-haul locomotives would apply to all
Tier 0, 1, and 2 locomotives and are based on engine design
improvements. The feasibility of the proposed standards and the
technologies involved are discussed in detail in section III.D. Table
III-1 summarizes the proposed line-haul locomotive standards and
implementation dates. See section III.C(3) for a discussion of the HC
standards.

                              Table III-1.--Proposed Line-Haul Locomotive Standards
                                                   [g/bhp-hr]
----------------------------------------------------------------------------------------------------------------
             Standards apply to:                             Date                    PM        NOX         HC
----------------------------------------------------------------------------------------------------------------
Remanufactured Tier 0 & 1....................  2008 as Available, 2010 Required       0.22    \a\ 7.4   \a\ 0.55
Remanufactured Tier 2........................  2008 as Available, 2013 Required       0.10        5.5       0.30
 New Tier 3..................................  2012............................       0.10        5.5       0.30
New Tier 4...................................  PM and HC 2015 NOX 2017.........       0.03        1.3       0.14
----------------------------------------------------------------------------------------------------------------
\a\ For Tier 0 locomotives originally manufactured without a separate loop intake air cooling system, these
  standards are 8.0 and 1.00 for NOX and HC, respectively.

(i) Remanufactured Locomotive Standards
    We have previously regulated remanufactured locomotive engines
under section 213(a)(5) of the Clean Air Act as new locomotive engines
and we propose to continue to do so in this rule. Under our proposed
standards, the existing fleet of locomotives that are currently subject
to Tier 0 standards (our current remanufactured engine standards) would
need to comply with a new Tier 0 PM standard of 0.22 g/bhp-hr (0.30 g/
kW-hr). They would also need to comply with a new Tier 0 NOX
line-haul standard of 7.4 g/bhp-hr (9.9 g/kW-hr), except that Tier 0
locomotives that were built without a separate coolant loop for intake
air (that is, using engine coolant for this purpose) would be subject
to a less stringent Tier 0 NOX standard of 8.0 g/bhp-hr
(10.7 g/kW-hr) on the line-haul cycle.
    These non-separate loop locomotives were generally built before
1993, though some are of more recent model years. Because of their age,
many of them are likely to be retired and not remanufactured again, and
many are entering lower use applications within the railroad industry.
Correspondingly, their contribution to the locomotive emissions
inventory is diminishing. Our analysis indicates that it is feasible to
obtain a NOX reduction for them on the order of 15 percent,
from the current Tier 0 line-haul NOX standard of 9.5 g/bhp-
hr to the proposed 8.0 g/bhp-hr standard. However, we expect that any
further reduction would require the addition of a separate intake air
coolant loop, which provides more efficient cooling and therefore lower
NOX. This would be a fairly expensive hardware change and
could have sizeable impacts on the locomotive platform layout and
weight constraints. We are aware that this group of older, non-separate
loop Tier 0 locomotives is fairly diverse, and that achieving even a
8.0 g/bhp-hr NOX standard along with a stringent Tier 0 PM
standard will be more difficult on some of these models than on others.
We request comment on whether there are any locomotive families within
this group for which meeting the proposed 8.0 g/bhp-hr standard may not
be feasible, especially considering the cost of doing so and the age of
the locomotives involved. Commenters should discuss feasibility and
projected costs, and should also discuss the extent to which this
concern is mitigated by the prospect that these locomotives will be
retired rather than remanufactured anyway, or will be moved to lower
usage switcher or small railroad applications, and therefore will be
less likely to be remanufactured under the new Tier 0 standards.
    We propose to apply the new Tier 0 standards (and corresponding
switch-cycle standards) when the locomotive is remanufactured on or
after January 1, 2008. However, if no certified emissions

control system exists for the locomotive before October 31, 2007, these
standards will instead apply 3 months after such a system is certified,
but no later than January 1, 2010. This would provide an incentive to
develop and certify systems complying with these standards as early as
possible, but allow the railroad to avoid having to delay planned
rebuilds if a certified system is not available when the program is
expected to begin in 2008. We also propose to include a reasonable cost
provision, described in section IV.B, to protect against the unlikely
event that the only certified systems made available when this program
starts in 2008 will be exorbitantly priced.
    Although under this approach, certification of new remanufacture
systems before 2010 is voluntary, we believe that developers would
strive to certify systems to the new standards as early as possible,
even in 2008, to establish these products in the market, especially for
the higher volume locomotive models anticipated to have significant
numbers coming due for remanufacture in the next few years. This focus
on higher volume products also maximizes the potential for large
emission reductions very early in this program, greatly offsetting the
effect of slow turnover to new Tier 3 and Tier 4 locomotives inherent
in this sector.
    We are also proposing to set new more stringent standards for
locomotives currently subject to Tier 1 and Tier 2 standards, to apply
at the point of next remanufacture after the proposed implementation
dates. Tier 1 locomotives would need to comply with the same new PM
standard of 0.22 g/bhp-hr (0.30 g/kW-hr) required of Tier 0 locomotives
(they are already subject to the 7.4 g/bhp-hr (9.9 g/kW-hr)
NOX standard). This in essence expands the model years
covered by the Tier 1 standards from 2002-2004 to roughly 1993-2004,
greatly increasing the size of the Tier 1 fleet while at the same time
reducing emissions from this broadened fleet. Under the proposal, Tier
2 locomotives on the rails today or built prior to the start of Tier 3
would need to comply with a new Tier 2 PM line-haul standard of 0.10 g/
bhp-hr (0.13 g/kW-hr). Because this is equal to the Tier 3 standard, it
essentially adds the entire fleet of Tier 2 locomotives to the clean
Tier 3 category over a period of just a few years, as they go through a
remanufacture cycle.
    The implementation schedule for the new Tier 1 standard would be
the same as the 2008/2010 schedule discussed above for Tier 0
locomotives. Meeting the new Tier 2 standard would be required somewhat
later, in 2013, reflecting the additional redesign challenge involved
in meeting this more stringent standard, and the need to spread the
redesign and certification workload faced by the manufacturers overall.
However, as for Tier 0 and Tier 1 locomotives, we are proposing that if
a certified Tier 2 remanufacture system meeting the new standard is
available early, anytime after January 1, 2008, this system would be
required to be used, starting 3 months after it is certified, subject
to a reasonable cost provision as with early Tier 0 and Tier 1
remanufactures. We request comment on whether use of certified Tier 2
remanufacture systems should be required on the same schedule as Tier
3, that is, starting in 2012, given that we expect the upgraded Tier 2
designs to be very similar to newly-built Tier 3 designs, and the
likelihood that substantial numbers of Tier 2 locomotives may be
approaching their first scheduled remanufacture by 2012.
    These proposed remanufactured locomotive standards represent PM
reductions of about 50 percent, and (for Tier 0 locomotives with
separate loop intake air cooling) NOX reductions of about 20
percent. Significantly, these reductions would be substantial in the
early years. This would be important to State Implementation Plans
(SIPs) being developed to achieve attainment with national ambient air
quality standards (NAAQS), owing to the 2008 start date and relatively
rapid remanufacture schedule (roughly every 7 years, though it varies
by locomotive model and age).
(ii) Newly-Built Locomotive Standards
    We are requesting comment on whether additional NOX
emission reductions would be feasible and appropriate for Tier 3
locomotives in the 2012 timeframe. There are proven diesel technologies
not currently employed in Tier 2 locomotives that can significantly
reduce NOX emissions, most notably cooled exhaust gas
recirculation (EGR). Although employed successfully in the heavy-duty
highway diesel sector since 2003, a considerable development and
redesign program would need to be undertaken by locomotive
manufacturers to apply cooled EGR to Tier 3 locomotives. This
development work would not be limited to the engine but would include
substantial changes to the locomotive chassis to handle the higher
levels of heat rejection (engine cooling demand) required for cooled
EGR. We project that it would require a similar degree of engineering
time and effort to develop a cooled EGR solution for locomotive diesel
engines as it will to develop the urea SCR based solution upon which we
are basing our proposed Tier 4 NOX standard. Therefore, we
have not considered the application of cooled EGR in setting our
proposed Tier 3 standard.
    It may be possible to reoptimize existing Tier 2 NOX
control technologies, most notably injection timing retard (used to
some degree on all diesel locomotives), to achieve a more modest
NOX reduction of 10 to 20 percent from the current Tier 2
levels. In fact, a version of General Electric's Tier 2 locomotive is
available today that achieves such NOX reductions for
special applications such as the California South Coast Locomotive
Fleet Average Emissions Program. In general, the use of injection
timing retard to control NOX emissions comes with a tradeoff
against fuel economy, durability and increased maintenance depending
upon the degree to which injection timing retard is applied. Experience
with on-highway trucks suggests that a 20 percent NOX
reduction based solely on injection timing retard could result in an
increase of fuel consumption as much as 5 percent. We request comment
on the feasibility and other impacts of applying technologies such as
these in the Tier 3 timeframe. We also request comment on the extent to
which any workload-based impediments to applying such technologies in
Tier 3 could be addressed via balancing it by obtaining less than the
proposed NOX reductions from remanufactured locomotives. We
believe that a Tier 3 NOX standard below 5 g/bhp-hr might be
achievable with a limited impact if additional engineering resources
were invested to optimize such a system for general line-haul
application. We encourage commenters supporting lower NOX
levels for Tier 3 locomotives to address whether some tradeoff in
engineering development (or emissions averaging) between new Tier 3
locomotives and remanufactured Tier 0 locomotives might be appropriate.
For example, would it be appropriate to set a Tier 3 NOX
standard at 4.5 g/bhp-hr, but relax the NOX standard for
later model Tier 0 locomotives to 8.0 g/bhp-hr instead of 7.4 g/bhp-hr?
    We are proposing that a manufacturer may defer meeting the Tier 4
NOX standard until 2017. However, we expect that each
manufacturer will undertake a single comprehensive redesign program for
Tier 4, using this allowed deferral to work through any implementation
and technology prove-out issues that might arise with advanced
NOX control technology, but relying on the same basic
locomotive platform and overall emission control space allocations for
all Tier 4 product years. For this reason we are proposing

that locomotives certified under Tier 4 in 2015 and 2016 without Tier 4
NOX control systems have this system added when they undergo
their first remanufacture, and be subject to the Tier 4 NOX
standard thereafter.
    We are proposing that, starting in Tier 4, line-haul locomotives
will not be required to meet standards on the switch cycle. Line-haul
locomotives were originally made subject to switch cycle standards to
help ensure robust control in use and in recognition of the fact that
many line haul locomotives have in the past been used for switcher
service later in life. As explained in section III.C(1)(b), the latter
is of less concern today. Also, we expect that the aftertreatment
technologies used in Tier 4 will provide effective control over a broad
range of operation, thus lessening the need for a switch cycle to
ensure robust control. We propose that newly-built Tier 3 locomotives
and Tier 0 through Tier 2 locomotives remanufactured under this program
be subject to switch cycle standards, set at levels above the line-haul
cycle standards (Table III-1) in the same proportion that the original
Tier 0 through Tier 2 switch cycle standards are above their
corresponding line-haul cycle standards. See section III.C(1)(b) for
details.
(b) Switch Locomotives
    Our 1998 locomotive rule included some provisions aimed at
addressing emissions from switch locomotives. We adopted a set of
switcher standards and a switcher test cycle. This cycle made use of
the same notch-by-notch test data as the line haul cycle, but
reweighted these notch-specific emission results to correspond to
typical switcher duty. In addition to controlling emissions from
dedicated switchers, we viewed this cycle as adding robustness to the
line-haul emissions control program. For this reason, and because aging
line-haul locomotives have often in the past found utility as
switchers, we subjected all regulated locomotives to the switch cycle.
We also allowed for dedicated switch locomotives, defined as
locomotives designed or used primarily for short distance operation and
using an engine with rated power at 2300 hp (1700 kW) or less, to be
optionally exempted from the line-haul cycle standards.
    There have been a number of changes in the rail industry since our
1998 rulemaking that are relevant to switchers. First, locomotives
marketed for line-haul service have continued to increase in size, to a
point where today's 4000+hp (3000+kW) line-haul locomotives are too
large for practical use in switching service. Second, there have been
practically no U.S. sales of newly-built switchers by the primary
locomotive builders, EMD and GE, for many years. Third, smaller
builders have entered this market, selling new or refurbished
locomotives with one to three newly-built diesel engines originally
designed for the nonroad equipment market, but recertified under Part
92, or sold under the 40 CFR 92.907 provisions that allow limited sales
of locomotives using nonroad-certified engines. Fourth, although this
new generation of switchers has shown great promise, their purchase
prices on the order of a million dollars or more, compared to the
relatively low cost of maintaining old switchers, have limited sales
primarily for use in California and Texas where state government
subsidies are available.
    All of these factors together have produced a situation in which
the current fleet of old switchers, including many pre-1973 locomotives
not subject to any emissions standards, is maintained and kept in
service. Because they have relatively light duty cycles and generally
operate very close to repair facilities, they can be maintained almost
indefinitely. Though many have poor fuel economy, this alone is not of
great enough concern to the railroads to warrant replacing them because
even very busy switchers consume a fraction of the fuel used by long-
distance line-haul locomotives.
    At the same time, these older switch locomotives have come under
increasing public scrutiny. When operated in railyards located in urban
neighborhoods, they have often become the focus of complaints from
citizens groups about noise, smoke, and other emissions, and state and
local governments have begun to place a higher priority on reducing
their emissions.\101\
---------------------------------------------------------------------------

    \101\ See, for example, letter from Catherine Witherspoon,
Executive Director of the California Air Resources Board, to EPA
Administrator Stephen Johnson, September 7, 2006.
---------------------------------------------------------------------------

    We note that switchers (or any other locomotives) that have not
been remanufactured to EPA standards are not considered covered by the
full preemption of state and local emission standards in section
209(e)(1) of the Clean Air Act, which applies to standards relating to
the control of emissions from new locomotive engines. Similarly, the
preemption that does apply for locomotives that are certified to EPA
standards does not generally apply for any locomotive that has
significantly exceeded its useful life. The provisions of section
209(e)(2) pertaining to other nonroad engines would apply for such
engines, as well as other engines used in locomotives excluded from the
definition of ``new.'' Such engines may be subject to regulation by
California and other states.
    As discussed in section II.B, we too are concerned that emissions
from locomotives in urban railyards, many of which are switch
locomotives, are causing substantial adverse health effects. Some
railroads have been attempting to address these concerns, adopting
voluntary idling restrictions and, where government subsidies are
available, replacing older switchers with cleaner, quieter new-
generation switchers. In light of these trends and market realities, we
believe it is appropriate to propose standards and other provisions
specific to switch locomotives, aimed at obtaining substantial overall
emission reductions from this important fleet of locomotives.
    We are proposing Tier 3 and 4 emission standards for newly-built
switch locomotives, shown in Table III-2, based on the capability of
the Tier 3 and 4 nonroad engines that will be available to power switch
locomotives in the future under our clean nonroad diesel program. We
propose to retain the existing switch locomotive test cycle upon which
compliance with these standards would be measured, but not to apply the
line-haul standards and cycle to Tier 3 and 4 switchers, in light of
the divergence that has occurred in the design of newly-built switch
and line-haul locomotives. We also propose that Tier 0, 1, and 2 switch
locomotives certified only on the switch cycle (as allowed in our Part
92 regulations), be subject to a set of remanufactured locomotive
standards equivalent to our proposed program for remanufactured line-
haul locomotives, with proportional levels of emission reductions.
These standards are also the switch cycle standards for the Tier 3 and
earlier line-haul locomotives that are subject to compliance
requirements on the switch cycle. In the case of the Tier 3 line-haul
locomotives, we are proposing that the Tier 2 switch cycle standards be
applied rather than the Tier 3 standards for dedicated switchers
because the latter are based on nonroad engines.

                        Table III-2.--Proposed Emission Standards for Switch Locomotives
                                                   [g/bhp-hr]
----------------------------------------------------------------------------------------------------------------
  Switch locomotive standards
           apply to:                 PM        NOX         HC                          Date
----------------------------------------------------------------------------------------------------------------
Remanufactured Tier 0..........       0.26       11.8       2.10  2008 as available, 2010 required.
Remanufactured Tier 1..........       0.26       11.0       1.20  2008 as available, 2010 required.
Remanufactured Tier 2..........       0.13        8.1       0.60  2008 as available, 2013 required.
Tier 3.........................       0.10        5.0       0.60  2011.
Tier 4.........................       0.03        1.3       0.14  2015.
----------------------------------------------------------------------------------------------------------------

    Standards and implementation dates for large nonroad engines vary
by horsepower and by whether or not the engine is designed for portable
electric power generation (gensets), as shown in Table III-3. This is
significant for the switch locomotive program because it has been the
practice for switch locomotive builders to use a variety of nonroad
engine configurations. For example, a manufacturer building a 2100 hp
switcher using nonroad engines in 2011 could team three 700 hp engines
designed to the nonroad Tier 4 standards of 0.01 g/bhp-hr PM and 0.30
g/bhp-hr NOX, or two 1050 hp engines at 0.075/2.6 g/bhp-hr
PM/NOX, or a single 2100 hp engine at 0.075/0.50 or 0.075/
2.6 g/bhp-hr PM/NOX, depending on if the engine is a genset
engine or not.
    As discussed in the nonroad Tier 4 rulemaking in which we set these
standards, we believe that the standards set for all of these nonroad
engines achieve the greatest degree of emission reduction achievable
through the application of technology which the Administrator
determines will be available, with appropriate consideration to factors
listed in the Clean Air Act. There are reasons for a switcher
manufacturer to choose one configuration of engines over another
related to function, packaging, reliability and other factors. We
believe that limiting a manufacturer's choice to only the cleanest
configuration in any given year would hinder optimum designs and
thereby would tend to work against our goal of encouraging the turnover
of the current fleet of old switchers. Furthermore, we note that there
is no single large engine category that consistently has the most
stringent nonroad Tier 4 PM and NOX standards from year to
year. We also note that, because State subsidies for the purchase of
new switch locomotives have been clearly tied to their lower emissions,
and also because the use of lower-emitting engines can generate
valuable ABT credits, there is likely to be continuing pressure driving
the industry toward the cleanest nonroad engines available in whatever
new switcher market does develop.

                               Table III-3.--Large Nonroad Engine Tier 4 Standards
                                                   [g/bhp-hr]
----------------------------------------------------------------------------------------------------------------
                           Rated power                                 PM             NOX           Model year
----------------------------------------------------------------------------------------------------------------
[lE]750 hp.......................................................       0.01  \a\ 3.0 (NOX+NMHC)            2011
                                                                        0.01                0.30            2014
750-1200 hp......................................................      0.075                 2.6            2011
                                                                        0.02            \b\ 0.50            2015
>1200 hp.........................................................      0.075            \b\ 0.50            2011
                                                                        0.02            \b\ 0.50            2015
----------------------------------------------------------------------------------------------------------------
a 0.30 NOX for 50% of sales in 2011-2013, or alternatively 1.5 g NOX for 100% of sales.
b 2.6 for non-genset engines--setting the long-term Tier 4 standard for these engines was deferred in the
  Nonroad Tier 4 Rule.

    There is one exception to this approach that we consider necessary.
In the Tier 4 nonroad engine rule, we deferred setting a final Tier 4
NOX standard for non-genset engines over 750 hp. These are
typically used in large bulldozers and mine haul trucks. This was done
in order to allow additional time to evaluate the technical issues
involved in adapting NOX control technology to these
applications and engines (69 FR 38979, June 29, 2004). We believe it is
appropriate to propose a Tier 4 NOX standard for switch
locomotives in 2015 based on SCR technology, as we are proposing for
line-haul locomotives in 2017. We believe this to be feasible because
the switch locomotive designer will have a variety of nonroad engine
choices equipped with SCR available in 2015, such as multiple < 750 hp
engines or larger genset engines, an opportunity that is not available
to large nonroad machine designers due to functional and packaging
constraints. To set a non-SCR based standard for switch locomotives
indefinitely, or to wait to do so after we set the final Tier 4
NOX standard for mobile machine engines above 750 hp, would
create significant uncertainty for the manufacturers and railroads, and
would be contrary to our intent to reduce locomotive emissions in
switchyards. We note too that SCR introduction in the fairly limited
fleet of newly-built switchers likely to exist in 2015 and 2016
provides an opportunity for railroads to become familiar with urea
handling and SCR operation in accessible switchyards, before large
scale introduction in the far-ranging line-haul fleet.
    Although we are factoring the current practice of building new
switchers powered by nonroad-certified engines into the design of the
program, it is not our intent to discourage the development and sale of
traditional medium-speed engine switch locomotives. We have evaluated
the proposed Tier 3 and 4 standards in this context and have concluded
that they will be feasible for switchers using medium-speed engines as
well as higher-speed nonroad engines.
    Because in today's market the certifying switch locomotive
manufacturer is typically a purchaser of nonroad engines and not
involved in their design, we see the value in providing a streamlined
option to help in the early implementation of this program. As
described in Section IV, we are proposing that, for a program start-

up period sufficient to encourage the turnover of the existing switcher
fleet to the new cleaner engines, switch locomotives may use nonroad-
certified engines without need for certification under the locomotive
program. Because of large differences in how the locomotive and nonroad
programs operate in such areas as useful life and in-use testing, we do
not believe it appropriate to allow locomotive ABT credits to be
generated or used by locomotives sold under this option, though of
course this would not preclude nonroad engine ABT credits under that
program. For the same reasons, we also think it makes sense to
eventually sunset this option after it has served its purpose of
encouraging the early introduction of new low-emitting switch
locomotives. We propose that the streamlined path be available for 10
years, through 2017, and ask for comment on whether a shorter or longer
interval is appropriate, taking into account the turnover incentive
provisions described below. We are proposing other compliance and ABT
provisions relevant to switch locomotives as discussed in section
IV.B(1), (2), (3), and (9).
    Finally, we are proposing a rewording of the definition of a switch
locomotive to make clear that it is the total switch locomotive power
rating that must be below 2300 hp to qualify, not the engine power
rating, and to drop the unnecessary stipulation that it be designed or
used primarily for short distance operation. This clears up the
ambiguity in the current definition over multi-engine switchers.
(c) Reduction of Locomotive Idling Emissions
    Even in very efficient railroad operations, locomotive engines
spend a substantial amount of time idling, during which they emit
harmful pollutants, consume fuel, create noise, and increase
maintenance costs. A significant portion of this idling occurs in
railyards, as railcars and locomotives are transferred to build up
trains. Many of these railyards are in urban neighborhoods, close to
where people live, work, and go to school.
    Short periods of idling are sometimes unavoidable, such as while
waiting on a siding for another train to pass. Longer periods of idling
operation may be necessary to run accessories such as cab heaters/air
conditioners or to keep engine coolant (generally water without anti-
freeze to maximize cooling efficiency) from freezing and damaging the
engine if an auxiliary source of heat or power is not installed on the
locomotive. Locomotive idling may also occur due to engineer habits of
not shutting down the engine, and the associated difficulty in
determining just when the engine can be safely shut down and for how
long.
    Automatic engine stop/start (AESS) systems have been developed to
start or stop a locomotive engine based on parameters such as: ambient
temperature, battery charge, water and oil temperature, and brake
system pressure. AESS systems have been proven to reliably and safely
reduce unnecessary idling. Typically they will shutdown the locomotive
after a specified period of idling (typically 15-30 minutes) as long as
the parameters are all within their required specifications. If one of
the aforementioned parameters goes out of its specified range, the AESS
will restart the locomotive and allow it to idle until the parameters
have returned to their required limits. Although developed primarily to
save fuel, AESS systems also reduce idling emissions and noise by
reducing idling time. Any emissions spike from engine startup has been
found to be minor, and thus idle emissions are reduced in proportion to
idling time eliminated. It is expected that overall PM and
NOX idling emission reductions of up to 50 percent can be
achieved through the use of AESS.
    A further reduction in idling emissions can be achieved through the
use of onboard auxiliary power units (APUs), either as standalone
systems or in conjunction with an AESS. There are two main
manufacturers of APUs, EcoTrans which manufacturers the K9 APU, and Kim
Hotstart which manufactures the Diesel Driven Heating System (DDHS). In
contrast to AESS, which works to reduce unnecessary idling, the APU
goes further by also reducing the amount of time when locomotive engine
idling is necessary, especially in cold weather climates. APUs are
small (less than 50 hp) diesel engines that stop and start themselves
as needed to provide heat to both the engine coolant and engine oil,
power to charge the batteries and to run necessary accessories such as
those required for cab comfort. This allows the much larger locomotive
engine to be shut down while the locomotive remains in a state of
readiness thereby reducing fuel consumption without the risk of the
engine being damaged in cold weather. If an APU does not have the
capability of an AESS built in, it may need to be installed in
conjunction with one in order to receive the full complement of idle
reductions that the combination of technologies can provide. The APUs
are nonroad engines compliant with EPA or State of California nonroad
engine standards, and emit at much lower levels than an idling
locomotive.
    Installation of an APU today costs approximately $25,000 to
$35,000; while an AESS can cost anywhere from $7,500 to $15,000.\102\
The costs vary depending on the model and configuration of the
locomotive on which the equipment is being installed, and would likely
be substantially lower if incorporated into the design of a newly-built
locomotive. The amount of idle reduction each system can provide is
also dependent on a number of variables, such as what the function of
the locomotive is (e.g. a switcher or a line-haul), where it operates
(i.e. geographical area), and what its operating characteristics are
(e.g. number of hours per day it operates). The duty cycles in 40 CFR
92.132, based on real world data available at the time they were
adopted in 1998, indicate a line haul locomotive idles nearly 40% of
its operating time, and a switcher locomotive idles nearly 60% of its
operating time. This idling time can be further divided into low idle
(when there is no load on the engine) and normal idle (when there is a
load on the engine). Only low idle can be reduced by an AESS, while an
APU can reduce normal idle (or idle in a higher notch such as notch 3
which can burn up to 11 gallons per hour). Another difference between
the two types of idle is the fuel consumption rate which is less at low
idle than normal idle (2.4-3.6 gallons per hour vs. 2.9-5.4 gallons per
hour, based on Tier 2 certification data).
---------------------------------------------------------------------------

    \102\ Jessica Montanez and Matthew Mahler, ``Reducing Idling
Locomotives Emissions'', NC Department of Environment and Natural
Resources, DAQ http://daq.state.nc.us/planning/locoindex.shtml.

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

    Although there is a gradual trend in the railroad industry toward
wider use of these types of idle control devices, we believe it is
important for ensuring air quality benefits to propose that idle
controls be required as part of a certified emission control system. We
are proposing that at least an AESS system be required on all new Tier
3 and Tier 4 locomotives, and also installed on all existing
locomotives that are subject to the new remanufactured engine
standards, at the point of first remanufacture under the new standards,
unless the locomotive is already equipped with idle controls.
Specifically, we are requiring that locomotives equipped with an AESS
device under this program must shut down the locomotive engine after no
more than 30 continuous minutes of idling, and be able to stop and
start the engine at least six times per day without

causing engine damage or other serious problems. The system must
prevent the locomotive engine from being restarted to resume extended
idling unless one of the following conditions necessitates such idling:
to prevent engine damage such as damage caused by coolant freezing, to
maintain air brake pressure, to perform necessary maintenance, or to
otherwise comply with applicable government regulations. EPA approval
of alternative criteria could be requested provided comparable idle
emissions reduction is achieved.
    As described in the RIA, it is widely accepted that for most
locomotives, the fuel savings that result in the first several years
after installation of an AESS system will more than offset the cost of
adding the system to the locomotive. Given these short payback times
for adding idle reduction technologies to a typical locomotive, normal
market forces have led the major railroads to retrofit many of their
locomotives with such controls. However, as is common with pollution,
market forces generally do not account for the external social costs of
the idling emissions. This proposal addresses those locomotives for
which the railroads determine that the fuel savings are insufficient to
justify the cost of the retrofit. We believe that applying AESS to
these locomotives is appropriate when one also considers the very
significant emissions reductions that would result, as well as the
longer term fuel savings. We request comment on the need for this
requirement. We also request comment regarding the reasons why a
railroad might choose not to apply AESS absent this provision. Are
there costs for AESS and retrofits that are higher than our analysis
would suggest? Are there other reasons that would lead a railroad to
not adopt AESS universally?
    Even though we are proposing to require only AESS systems, we
encourage the additional use of APUs by providing in our proposed test
regulations a way for the manufacturer to appropriately account for the
emission benefits of greater idle reduction. See Section IV.B(8) for
further discussion. We are not proposing that APUs must be installed on
every locomotive because it is not clear how much additional benefit
they would provide outside of regions and times of the year where low
temperatures or other factors that warrant the use of an APU exist, and
they do involve some inherent design and operational complexities that
could not be justified without commensurate benefits. We are however
asking for comment on requiring that some subset of new locomotives be
equipped with APUs where feasible and beneficial. We are also asking
for comments on whether to adopt a regulatory provision that would
exempt a railroad from AESS and/or APU requirements if it demonstrated
that it was achieving an equal or greater degree of idle reduction
using some other method.
(d) Load Control in a Locomotive Consist
    A locomotive consist is the linking of two or more locomotives in a
train, typically where the lead locomotive has control over the power
and dynamic brake settings on the trailing locomotives. For situations
where locomotives are operated in a consist, EPA is requesting comment
on how the engine loads could be managed in a way which reduces the
combined emissions of the consist, and in what way our program can be
set up to encourage such reductions. Consists are commonly used in long
trains to achieve the power and traction levels necessary to move,
stop, and control the train. The trailing locomotives can be directly-
coupled to the lead locomotive, or, they may be placed anywhere along
the train and controlled remotely by the lead. The load settings of the
individual locomotives that make up a consist are not always equal--for
example, if the train has crested a hill, the leading locomotive(s)
could be operating under dynamic brake (to control the speed of the
train) while the trailing locomotives could be producing propulsion
power (to reduce strain on the couplers). Depending on the load, track,
terrain, and weather conditions, it is conceivable that the engine
loads of a consist could be managed to provide the lowest fuel
consumption for the power/traction needed. For example, the train power
can be distributed so that the lead engine is operating at its optimum
brake-specific fuel consumption point while trailing engines are
operated at reduced power settings and/or shut down. The capability to
manage and distribute engine power in a locomotive consist is available
on the market today.
    We have been made aware that it may be possible to optimize the
configuration of locomotives in a consist for emissions performance
without compromising other key goals such as fuel economy and safety.
Our proposed regulations do not explicitly take such possible
optimization into account. However, if commenters believe that
significant emission reductions can be attained by controlling the
engine loads in a consist (beyond those attained by the current
practice of operating the consist to achieve the lowest fuel
consumption rate), we would solicit their views on how to calculate the
emissions reduction and on how the in-use operation of the consist
could be logged and reported. For example, it may be appropriate to
allow a manufacturer to use alternative notch weightings tailored to
operation in an emissions-optimized consist in demonstrating compliance
with the emissions standards, thus providing added flexibility in
designing such locomotives to meet the standards.
(2) Marine Standards
    We are also proposing new emissions standards for newly-built
marine diesel engines with displacements under 30 liters per cylinder,
including those used in commercial, recreational, and auxiliary power
applications. As for locomotives, our ANPRM described a one-step marine
diesel program that would bring about the introduction of high-
efficiency exhaust aftertreatment in this sector. Just as for
locomotives, our analyses of the technical issues related to the
application of aftertreatment technologies to marine engines, informed
by our many discussions with stakeholders, have resulted in a proposal
for new standards in multiple steps, focused especially on the engines
with the greatest potential for large PM and NOX emission
reductions. Our technical analyses are summarized in section III.D and
are detailed in the draft RIA.
    In contrast to the locomotive sector, the marine diesel sector
covered by this rule is quite diverse. Commercial propulsion
applications range from small fishing boats to Great Lakes freighters.
Recreational propulsion applications range from sailboats to super-
yachts. Similarly, auxiliary power applications range from small
gensets, to generators used on barges, to large power-generating units
used on ocean-going vessels. Many of the propulsion engines are used to
propel high-speed planing boats, both commercial and recreational,
where low weight and high power density are critically important. Some
engines are situated in crowded engine compartments accessed through a
hatch in the deck, while others occupy relatively spacious engine
rooms. All of them share a high premium on reliability, considering the
potentially serious ramifications of engine failure while underway.
    The resulting diversity in engine design characteristics is
correspondingly large. Sizes range from a few horsepower to thousands
of horsepower. Historically, we have categorized marine engines for
standards-setting purposes based on

cylinder displacements: C1 engines of less than 5 liters/cylinder, C2
from 5 to 30 liters/cylinder, and Category 3 (C3) at greater than 30
liters/cylinder. (These C3 engines typically power ocean-crossing ships
and burn residual fuel; we are not including such engines in this
proposal). Our past standard-setting efforts have found it helpful to
make further distinctions as well, considering small (less than 37 kW
(50 hp)) engines and C1 recreational engines as separate categories.
    Recreational engines typically power recreational vessels designed
primarily for speed, and this imposes certain constraints on the type
of engine they can use. For a marine vessel to reach high speeds, it is
necessary to reduce the surface contact between the vessel and the
water, and consequently these vessels typically operate in a planing
mode. Planing imposes important design requirements, calling for low
vessel weight and short periods of very high power-- and thus prompting
a need for high power density engines. The tradeoff is less durability,
and recreational engines are correspondingly warranted for fewer hours
of operation than commercial marine engines. These special
characteristics are represented in EPA duty-cycle and useful life
provisions for recreational marine engines.
    Unlike the locomotive sector, the vast majority of marine diesel
engines are derivatives of land-based nonroad diesel engines. Marine
diesel engine sales are significantly lower (by 10 or even 100 fold)
than the sales of the land-based nonroad engines from which they are
derived. For this reason, changes to marine engine technology typically
follow the changes made to the parent nonroad engine. For example, it
may be economically infeasible to develop and introduce a new fuel
system for a marine diesel engine with sales of 100 units annually,
while being desirable to do so for a land-based nonroad diesel engine
with sales of 10,000 or more units annually. Further, having developed
a new technology for land-based diesel engines, it is often cheaper to
simply apply the new technology to the marine diesel engine rather than
continuing to carry a second set of engine parts within a manufacturing
system for a marginal number of additional sales. Recognizing this
reality, our proposed marine standards are phased in to follow the
introduction of similar engine technology standards from our Nonroad
Tier 4 emissions program. In most cases, the corresponding marine
diesel standards will follow the Nonroad Tier 4 standards by one to two
years.
    We are proposing to retain the per-cylinder displacement approach
to establishing cutpoints for standards, but are revising and refining
it in several places to ensure that the appropriate standards apply to
every group of engines in this very diverse sector, and to provide for
an orderly phase-in of the program to spread out the redesign workload
burden:
    (1) We are proposing to move the C1/C2 cutpoint from 5 liters/
cylinder to 7 liters/cylinder, because the latter is a more accurate
cutpoint between today's high- and medium-speed diesels (in terms of
revolutions per minute (rpm)), with their correspondingly different
emissions characteristics.
    (2) We also propose to revise the per-cylinder displacement
cutpoints within Category 1 to better refine the application of
standards.
    (3) An additional differentiation is proposed between high power
density engines typically used in planing vessels and standard power
density engines, with a cutpoint between them set at 35 kW/liter (47
hp/liter). In addition to recreational vessels, the high power-density
engines are used in some commercial vessels, including certain kinds of
crew boats, research vessels, and fishing vessels. Unlike most
commercial vessels, these vessels are built for higher speed, which
allows them to reach research fields, oil platforms, or fishing beds
more quickly. This proposal addresses the technical challenges related
to reducing emissions from engines with high power density.
    (4) In the past, we did not formally include marine diesels under
37 kW (50 hp) in Category 1, but regulated them separately as part of
the nonroad engine program, referring to them elsewhere as ``small
marine engines''. They are typically marinized land-based nonroad
diesel engines. Because we are now proposing to include these engines
in the current marine diesel rulemaking, this distinction is no longer
needed and so we are including these engines in Category 1 for Tier 3
and Tier 4 standards.
    (5) Finally, we would further group engines by total rated power,
especially in regard to setting appropriate long-term aftertreatment-
based standards.
    Note that we are retaining the differentiation between recreational
and non-recreational marine engines within Category 1 because there are
differences in the proposed standards for them.
    Although this carefully targeted approach to standards-setting
results in a somewhat complicated array of emissions standards, we
believe it is justified because it maximizes overall emission
reductions by ensuring the most stringent standards feasible for a
given group of marine engines, and it also helps engine and vessel
designers to implement the program in the most cost effective manner.
The proposed standards and implementation schedules are shown on Tables
III-4-7.
    Briefly summarized, the proposed marine diesel standards include
stringent engine-based Tier 3 standards, phasing in over 2009-2014. In
addition, the proposed standards include aftertreatment-based Tier 4
standards for engines at or above 600 kW (800 hp), phasing in over
2014-2017, except that Tier 4 would not apply to recreational engines
under 2000 kW (2670 hp). For engines of power ratings not included in
the Tier 3 and Tier 4 tables, the previous tier of standards (Tier 2 or
Tier 3, respectively) continues to apply.

         Table III-4.--Proposed Tier 3 Standards for Marine Diesel C1 Commercial Standard Power Density
----------------------------------------------------------------------------------------------------------------
                                                                         PM  g/bhp-   NOX+HC  g/
                       Rated kW                           L/cylinder         hr         bhp-hr      Model year
----------------------------------------------------------------------------------------------------------------
< 19 kW................................................            < 0.9         0.30          5.6            2009
19-< 75 kW.............................................        \a\ < 0.9         0.22          5.6            2009
                                                        ..............     \b\ 0.22      \b\ 3.5            2014
75-3700 kW............................................            < 0.9         0.10          4.0            2012
                                                              0.9-< 1.2         0.09          4.0            2013
                                                              1.2-< 2.5     \c\ 0.08          4.2            2014
                                                              2.5-< 3.5     \c\ 0.08          4.2            2013
                                                              3.5-< 7.0     \c\ 0.08          4.3            2012
----------------------------------------------------------------------------------------------------------------
\a\ < 75 kW engines at or above 0.9 L/cylinder are subject to the corresponding 75-3700 kW standards.
\b\ Option: 0.15 PM/4.3 NOX in 2014.

\c\ This standard level drops to 0.07 in 2018 for < 600 kW engines.

   Table III-5.--Proposed Tier 3 Standards for Marine Diesel C1 Recreational and Commercial High Power Density
----------------------------------------------------------------------------------------------------------------
                                                                         PM  g/bhp-   NOX+HC  g/
                       Rated kW                           L/cylinder         hr         bhp-hr      Model year
----------------------------------------------------------------------------------------------------------------
< 19 kW................................................            < 0.9         0.30          5.6            2009
19-< 75 kW.............................................        \a\ < 0.9         0.22          5.6            2009
                                                        ..............     \b\ 0.22      \b\ 3.5            2014
                                                                  < 0.9         0.11          4.3            2012
75--3700 kW...........................................        0.9-< 1.2         0.10          4.3            2013
                                                              1.2-< 2.5         0.09          4.3            2014