United States Air and Radiation EPA420-F-99-001
Environmental Protection January 1999
Agency
Office of Mobile Sources
v>EPA Regulatory
Update
EPA's Nonroad Engine Emissions
Control Programs
In response to environmental and public health concerns, the U.S.
Environmental Protection Agency (EPA) has established emission
standards for several nonroad engine categories. The categories of
nonroad engines currently being addressed by EPA cover a variety of
applications, including farm and construction equipment, lawn and
garden equipment, marine vessels, and locomotives. As a whole, EPA's
nonroad programs will significantly reduce the impact of nonroad
equipment on the nation's air quality.
Background
EPA has been regulating highway cars and trucks since the early 1970s
and continues to set increasingly stringent standards for such vehicles.
After so much progress has been made in controlling the emissions from
highway vehicles, EPA turned its attention to nonroad categories of
mobile sources, which also contribute significantly to air pollution.
These nonroad control programs assist states in complying with the
National Ambient Air Quality Standards (NAAQS).
The 1990 Clean Air Act Amendments specifically directed EPA to study
the contribution of nonroad engines to urban air pollution, and regulate
them if warranted. "Nonroad" is a term that covers a diverse collection of
engines, equipment, and vehicles. Also referred to as "off-road" or "off-
highway," the nonroad category includes outdoor power equipment,
recreational equipment, farm equipment, construction equipment, lawn
and garden equipment, and marine vessels. Though dealt with separately
I Printed on Recycled Paper
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in the Clean Air Act, locomotives and
aircraft can also be considered categories
of nonroad engines. Except for aircraft,
nonroad engines were not regulated by
EPA prior to the mid-1990s.
In 1991, EPA released a study documenting
emission levels across a broad spectrum of
nonroad equipment that were higher than
expected. The EPA study showed that
emissions from nonroad engines are a
significant source of oxides of nitrogen
(NOx), volatile organic compound (VOC),
and particulate matter (PM) emissions.
1994 Nonroad NOx Emissions Inventory
Locomotives
30.6%
Source: EPA Trends Report, 10/95
Note: 1% = 31,000 tons
(Recreational Equipment is
<0.1% of inventory)
1994 Nonroad VOC Emissions Inventory
Locomotives
1.9%
Source: EPA Trends Report, 10/95
In some areas of the country, emissions
from nonroad engines represent a third of
the total mobile source NOx and VOC
inventory and over two-thirds of the mobile
source PM inventory.
1994 Nonroad PM-10 Emissions Inventory
Source: EPA Trends Report, 10/95
Note: 1%= 4,000
In response, EPA initiated regulatory
programs for several categories of nonroad
engines. The following sections summarize
the status of EPA s regulatory programs for
the various nonroad equipment categories.
Land-Based Diesel Engines
Nonroad diesel engines, also referred to as
compression-ignition engines, dominate the
large nonroad engine market and comprise
approximately 25 percent of the current
mobile source NOx emissions inventory
and 40 percent of the current mobile source
PM emissions inventory. Examples of
applications falling into this category
include: agricultural equipment such as
tractors; construction equipment such as
backhoes; material handling equipment
such as heavy forklifts; and utility equip-
ment such as generators and pumps.
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Under EPA regulations, diesel engines
greater than 50 horsepower (hp) must
comply with Tier 1 emissions standards
that are being phased in between 1996 and
2000, depending on the size of the engine.
Under the Tier 1 standards, EPA projects
that NOx emissions from new diesel
nonroad equipment will be reduced by over
30 percent from uncontrolled levels of
unregulated engines. The Tier 1 standards
do not apply to engines used in under-
ground mining equipment, locomotives,
and marine vessels. (The Mine Safety and
Health Administration is responsible for
setting requirements for underground
mining equipment. Locomotives and
marine vessels are covered by separate
EPA programs, as described below.)
Examples of Cl Equipment
tractors backhoes
bulldozers forklifts
generators pumps
In August 1998, EPA adopted more strin-
gent emission standards for NOx, hydro-
carbons (HC), and PM for new nonroad
diesel engines, to be phased in over several
years beginning in 1999. Engines used in
underground mining equipment, locomo-
tives, and marine vessels over 50 hp are not
included. This comprehensive new program
includes the first set of standards for
nonroad diesel engines less than 50 hp to
be phased in from 1999 to 2000. It also
phases in more stringent Tier 2 standards
for all engine sizes from 2001 to 2006, and
yet more stringent Tier 3 standards for
engines over 50 hp from 2006 to 2008.
Finally, the new program includes a volun-
tary program to encourage the production
of advanced, very-low emitting engines.
Under these new standards, EPA projects
that emissions from new nonroad diesel
equipment will be further reduced by 60
percent for NOx and 40 percent for PM
compared to the emission levels of engines
meeting the Tier 1 standards.
Small Land-Based Spark-
Ignition Engines
Small spark-ignition (SI) engines (e.g.,
engines operating on gasoline, natural gas,
propane, or methanol) at or below 25 hp
(19 kilowatts) comprise about 9 percent of
the mobile source VOC inventory. These
small engines are used primarily in lawn
and garden equipment, such as lawn-
mowers, string trimmers, edgers, chain
saws, commercial turf equipment, and lawn
and garden tractors.
Under Phase 1 of EPAs regulations, new
small SI engines must comply with emis-
sion standards for HC, CO, and NOx
beginning in 1997. The Phase 1 standards
apply to all SI engines at or below 25 hp,
except for those used in aircraft, marine
vessels, and recreational equipment. EPA
expects that these Phase 1 standards will
result in a 32 percent reduction in HC
emissions from small SI engines.
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Examples of Small SI Equipment
augers brush cutters
chainsaws edgers
lawn mowers tillers
leaf blowers trimmers
Phase 2 regulations, including more strin-
gent emission levels and new provisions to
ensure low in-use emissions, are being
developed. The Phase 2 program may
reduce combined emissions of HC plus
NOx from these engines by approximately
60 percent beyond Phase 1 levels.
Large Land-Based Spark-
Ignition Engines
Spark-ignition engines above 25 hp are
currently not regulated by EPA. These
engines are used in a variety of industrial
equipment, including forklifts, airport
ground-service equipment, generators, and
compressors. The California Air Resources
Board adopted new emission standards for
these engines in October 1998. EPA in-
tends to pursue an emission control pro-
gram for these engines that would extend
the California requirements to the rest of
the nation. Application of basic automotive
emission control technologies to this
engine category would reduce NOx and
HC emissions by 70 to 90 percent.
Examples of Large SI Equipment
forklifts
airport ground-service equipment
generators
compressors
Engines used in recreational applications,
such as go-carts, all-terrain vehicles, and
snowmobiles, are not currently regulated
by EPA. EPA intends to pursue appropriate
emission standards for these engines.
Marine Engines
Like land-based nonroad engines, marine
engines serve a wide variety of applica-
tions. The smallest marine engines, virtu-
ally all of which use gasoline, are used in
recreational outboards and personal water-
craft. Small gasoline or diesel marine
engines provide auxiliary power on many
vessels. Larger marine engines provide
propulsion for both recreational and com-
mercial applications. Recreational
sterndrive and inboard engines tend to be
gasoline, though diesel engines are making
inroads into that market.
Commercial engines, virtually all diesel,
power vessels such as tugs, ferries, and
crew/supply boats. These engines also
provide auxiliary power on larger vessels.
The largest marine diesel engines, some-
times exceeding 60,000 hp, propel ocean-
going vessels. EPA intends to have emis-
sion control requirements for all marine
engines. Engines are grouped under three
control programs reflecting their applica-
tion and, to some extent, the fuel they use.
Gasoline Outboards and Personal
Watercraft Marine Engines
Gasoline outboards and personal watercraft
contribute about 5 percent of the national
mobile source VOC inventory. However, in
areas with large boat populations, the
contribution of these recreational marine
engines may exceed 10 percent of the
regional HC inventory. These engines
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typically employ 2-stroke technology,
which changed very little over the last 50
years.
Regulations to control exhaust emissions
from new outboards and personal water-
craft went into effect in July 1996. The
emission controls for these engines involve
increasingly stringent standards over the
course of a nine-year phase-in period
beginning in model year 1998. By the end
of the phase-in, each manufacturer must
meet an emission standard, on a corporate-
average basis, that represents a 75 percent
reduction in HC compared to unregulated
levels. The gradually decreasing emission
standard allows manufacturers to determine
the best approach to achieving the targeted
reductions over time. Manufacturers are
able to phase in the types of control tech-
nologies in the most sensible way, while
minimizing the cost impact to the con-
sumer.
Commercial Diesel Marine Engines
Commercial diesel marine engines contrib-
ute about 8 percent of the national mobile
source NOx inventory, and about 1 percent
of the national mobile source PM inven-
tory. In areas with large commercial ports
or near busy shipping lanes, the contribu-
tion of diesel marine engines to the local
NOx and PM inventory may be much
higher.
EPA proposed regulations for the control of
exhaust emissions from new marine diesel
engines in November 1998. The proposed
emission limits, which vary depending on
the size of the engine, are similar to emis-
sion limits for corresponding land-based
nonroad or locomotive engines. These
limits would apply beginning with engines
manufactured in 2004. In addition, a more
stringent set of emission limits based on
the nonroad Tier 3 approach will be evalu-
ated in 2003. At that time, EPA will con-
firm the Tier 3 limits or adjust them to
reflect the technologies manufacturers can
apply at that time. The more stringent Tier
3 emission limits would apply beginning
with engines manufactured in 2008.
The proposed emission limits for very large
commercial marine diesel engines are the
same as those contained in Annex VI of the
International Convention on the Prevention
of Pollution from Ships (MARPOL).
Consistent with MARPOL Annex VI, these
proposed limits will apply to engines
installed on ships constructed on or after
January 1, 2000.
Recreational Sterndrive and Inboard
Engines
Recreational sterndrive and inboard en-
gines can be either gasoline or diesel
engines. While their contribution to na-
tional mobile VOC and NOx levels is
smaller than the other two marine engine
categories, their emissions are expected to
increase due to the growing number of
recreational vessels. EPA did not finalize
emission limits for gasoline sterndrive and
inboard engines as part of the 1996 marine
rule. Likewise, EPA did not propose limits
for recreational diesel engines in the
commercial diesel engine rule. Conse-
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quently, these recreational engines remain
unregulated at this time. EPA has started in
a separate rulemaking to consider emission
limits for these engines however.
Locomotives
Locomotives are estimated to contribute
about 9 percent of the nationwide mobile
source NOx emissions inventory. These
engines are generally larger and last longer
than any land-based nonroad diesel en-
gines. In April 1998, EPA finalized emis-
sion standards for NOx, HC, carbon mon-
oxide (CO), PM, and smoke for locomo-
tives. The new standards are expected to
reduce NOx emissions by two-thirds, while
HC and PM emissions from these engines
will decrease by 50 percent.
A unique feature of the locomotive pro-
gram is that it includes emission standards
for remanufactured engines, including all
those that were originally built since 1973.
Regulation of the remanufacturing process
is critical because locomotives are gener-
ally remanufactured 5 to 10 times during
their total service lives, which is typically
40 years or more.
Three separate sets of emission standards
have been adopted, with applicability of the
standards dependent on the date a locomo-
tive is first manufactured. The first set of
standards (Tier 0) apply to locomotives and
locomotive engines originally manufac-
tured from 1973 through 2001, any time
they are manufactured or remanufactured.
The second set of standards (Tier 1) apply
to locomotives and locomotive engines
originally manufactured from 2002 through
2004. These locomotives and locomotive
engines will be required to meet the Tier 1
standards at the time of original manufac-
ture and at each subsequent remanufacture.
The final set of standards (Tier 2) apply to
locomotives and locomotive engines
originally manufactured in 2005 and later.
Tier 2 locomotives and locomotive engines
will be required to meet the applicable
standards at the time of original manufac-
ture and at each subsequent remanufacture.
Electric locomotives, historic steam-
powered locomotives, and locomotives
originally manufactured before 1973 do not
contribute significantly to the emissions
problem and, thus, are not included in this
rulemaking.
Aircraft
Aircraft emissions comprise less than 2
percent of the mobile source NOx emis-
sions inventory, but they are significant
contributors to the NOx inventory in some
cities. In addition, commercial aircraft
emissions are a fast growing segment of the
transportation emissions inventory. Aircraft
emissions are potentially important con-
tributors to global climate change and may
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also contribute to the depletion of the
stratospheric ozone layer.
Emission standards for gas turbine engines
that power civil aircraft have been in place
for about 20 years. Such engines are used
in virtually all commercial aircraft, includ-
ing both scheduled and freight airlines. The
standards do not apply to military or
general aviation aircraft. Controls on
engine smoke and prohibitions on fuel
venting were instituted in 1974 and have
been revised several times since then.
Beginning in 1984, limits were placed on
the amount of unburned HC gas turbine
engines can emit per landing and takeoff
cycle.
In April 1997, EPA adopted the existing
International Civil Aviation Organization
(ICAO) NOx and CO emission standards
for gas turbine engines. ICAO, a special-
ized agency of the United Nations, is the
most appropriate forum for first establish-
ing commercial aircraft engine emission
standards due to the international nature of
the aviation industry.
EPA is also exploring other ways to reduce
the environmental effects associated with
air travel throughout the nation. EPA is
working with the Federal Aviation Admin-
istration (FAA) to encourage continuing
progress in reducing emissions from airport
ground service equipment and aircraft
auxiliary power units. EPA sponsored
compilation of technical data and emission
inventory methods, which the FAA will use
to develop an Advisory Circular for airlines
and airport authorities interested in reduc-
ing emissions from these sources.
For More Information
Additional documents on nonroad engine
programs are available electronically from
the EPA Internet server at:
www.epa.gov/oms/nonroad.htm
Document information is also available by
writing to:
U.S. Environmental Protection Agency
Office of Mobile Sources
2000 Traverwood Drive
Ann Arbor, Michigan 48105
EPA has additional fact sheets that go into
more detail on these nonroad engine
control programs:
General:
• Emission Standards Reference Guide for
Heavy-Duty and Nonroad Engines,
October 1997: map format (EPA420-F-
97-014); poster (EPA420-H-97-001).
• Nonroad Engines and Air Pollution
(EPA420-F-94-003), May 1996.
Land-Based Diesel Engines:
• New Emission Standards for Nonroad
Diesel Engines (EPA420-F-98-034),
August 1998.
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« Notice of Proposed Rulemaking:
Nonroad Diesel Engine Emissions
(EPA420-F-97-020), October 1997.
• Statement of Principles for Nonroad
Diesel Engines (EPA420-F-96-015),
September 1996.
Small Spark-Ignition
Engines:
« Small Engine Emission Standards
Answers to Commonly Asked Questions
from Dealers and Distributors (EPA420-
'p-98-025), September 1998.
« Proposed Phase 2 Standards for Small
Spark-Ignited Engines (EPA420-F-97-
045), December 1997.
• Nonroad. Phase 2 Small Spark-Ignited
Engines Advance Notice of Proposed
Rulemaking (EPA420-F-97-001), March
1997.
« Statement of Principles for Small
Nonhandheld Spark-Ignited Engines
(EPA420-F-97-002), January 1997.
« Statement of Principles for Small
Handheld, Gasoline Engines (EPA420-F-
96-001), May 1996.
• Be a Grower, Not a Mower (EPA420-F-
96-018), April 1997.
Spark-Ignition
Engines:
* Proposed Finding on Emission Stan-
dards for New Large Spark-Ignition
Nonroad Engines (EPA420-F-99-004),
January 1999.
• Proposed Emission Standards for New
CIMarine Engines (EPA420-F-98-044),
November 1998.
• Advance Proposal for Emission Stan-
dards/or New Diesel Marine Engines
(EPA420-F-98-006), May 1998.
• Emission Standards for New Gasoline
Marine Engines (EPA420-F-96-012),
August 1996.
• Emission Standards for New Spark-
Ignition Marine Engines: Information
for the Marine Industry (EPA420-F-96-
013), August 1996.
* Boating Pollution Prevention Tips
(EPA420-F-96-003), July 1996.
Locomotives:
• Final Emission Standards for Locomo-
tives (EPA420-F-97-048), December
1997.
* Federal Preemption of State and Local
Control of Locomotives (EPA420-F-97-
050), December 1997.
• Environmental Benefits of Emission
Standards for Locomotives (EPA420-F-
97-049), December 1997.
• Emission Factors of Locomotives
(EPA420-F-97-051), December 1997.
Aircraft:
• Adopted A ircraft Engine Emission
Standards (EPA420-F-97-010), April
1997.
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