United States Air and Radiation EPA420-F-97-049
Environmental Protection December 1997
Agency
Office of Mobile Sources
vxEPA Regulatory
Announcement
Environmental Benefits of Emission
Standards for Locomotives
The Environmental Protection Agency (EPA) has established emission
standards for oxides of nitrogen (NOx), hydrocarbons (HC), carbon
monoxide (CO), particulate matter (PM) and smoke for newly manufac-
tured and remanufactured locomotives and locomotive engines, which
have previously been unregulated. The new standards will achieve
approximately a two-third reduction in NOx emissions, which is equiva-
lent to removing over thirty million passenger cars from the road. In
addition, HC and PM emissions will be reduced by 50 percent.
Overview of Rulemaking
EPA has finalized emission standards for locomotives that will provide
significant emission reductions, beginning in the year 2000, to help states
comply with National Ambient Air Quality Standards (NAAQS) for
ozone and PM. Since locomotive emissions have not been regulated
before, it was necessary for EPA to create a comprehensive program,
including not only emission standards, but also test procedures and a full
compliance program. There are three separate sets of emission standards,
with applicability of the standards dependent on the date a locomotive is
first manufactured. The first set of standards (Tier 0) apply to locomo-
tives and locomotive engines originally manufactured from 1973 through
2001, any time they are remanufactured in calendar year 2000 or later.
The second and third sets of standards (Tier 1 and Tier 2) apply to loco-
motives and locomotive engines originally manufactured on or after
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January 1, 2002 (Tier 2 standards will take effect on January 1, 2005).
These locomotives and locomotive engines will also be required to meet
the same standards at each subsequent remanufacture. The Agency has
also established a rigorous emission testing program to make sure that
locomotives comply with these standards for the life of the locomotive.
Health and Environmental Concerns
Most locomotives in the U.S. are powered by diesel engines. Thus
locomotives have significant NOx emissions, as well as HC and PM
emissions, all of which have significant health and environmental ef-
fects. NOx is a major component of smog and acid rain. NOx emissions
combine with HC in the atmosphere to form ground-level ozone, the
primary constituent of smog. Ozone is a highly reactive pollutant that
damages lung tissue, causes congestion, and reduces vital lung capacity,
in addition to damaging vegetation. Acid rain damages buildings and
crops, and degrades lakes and streams. NOx also contributes to the
formation of secondary PM, which causes headaches, eye and nasal
irritation, chest pain, and lung inflammation. Environmental impacts of
PM include reduced visibility and deterioration of buildings.
Locomotive Emission Inventories
Locomotive NOx emissions are estimated to represent about 5.5 percent
of NOx emissions from all mobile and stationary sources in the U.S.
Locomotive PM and HC emissions are both estimated to represent less
than one-quarter of one percent of total national emissions. Thus, the
focus of EPAs regulation was on NOx emission reductions. It should be
noted that in some urban areas that have very high rail traffic, such as
Chicago or El Paso, NOx emissions can represent about one-tenth of the
total NOx inventory.
Current National Locomotive Emission Inventories
Pollutant
NOx
PM-10
HC
Metric Tons Per
Year
1,093,000
27,000
42,000
Percent of Total
Inventory
(All Sources)
5.5
0.1
0.2
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Environmental Benefits of New Standards
When fully phased-in, the new emission standards will reduce NOx
emissions from locomotives by nearly two-thirds, and HC and PM
emissions by half. They will also achieve very significant emission
reductions in the near term, however. These reductions, which are shown
below, are being heavily relied upon by those areas that have very high
rail traffic, as well as Southern California, which has moderately high
rail traffic and very significant air quality needs. To put these national
NOx emission reductions into context, the 304,000 ton per year reduc-
tion expected in 2005 would be equivalent to removing nearly 20 mil-
lion passenger cars from the road. In addition, NOx emission reductions
will also lead to reductions in ambient concentrations of secondary PM.
It has been estimated that about 4 tons of nitrate particulate is formed
from every 100 tons of NOx emitted. Thus, the secondary PM reduction
expected in 2005 is about 12,000 tons per year.
Projected National Emission Reductions (Metric Tons)
Pollutant
NOx
PM
HC
Secondary
PM*
Year
2005
304,000
900
1,400
12,000
2010
449,000
4,400
6,300
18,000
2015
496,000
6,000
8,700
20,000
2020
538,000
7,600
11,000
21,000
* Assumes 4 tons of nitrate paniculate formed for each 100 tons of NOx emitted.
Reductions from Existing Locomotive Fleet
Much of the expected reduction in NOx emissions will come early in the
program due to the Tier 0 standards that apply to existing locomotives
when they are remanufactured. These standards are a unique feature of
this regulation, and represent the first time that EPA has regulated the
remanufacturing of an existing fleet on such a large scale. Such regula-
tion of the remanufacturing process is critical because locomotives are
generally remanufactured five to ten times during their total service lives
(typically 40 years or more). Standards that would only apply to loco-
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motives originally manufactured after the effective date of the rule would
not achieve significant emissions reductions until those future locomo-
tives replaced a significant number locomotives in the existing fleet. For
the first 10 years of the program, the majority of projected NOx emission
reductions will be the result of the Tier 0 emission standards that apply to
existing locomotives.
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For More Information
The final rule and other documents on locomotives are available elec-
tronically from the EPA Internet server at:
http://www.epa.gov/OMSWWW/locomotv.htm
Document information is also available by contacting Russ Banush at:
U.S. Environmental Protection Agency
2565 Plymouth Road
Ann Arbor, MI 48105
(734)668-4333.
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