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Regulatory

Announcement

 Printed on Recycled Paper

United States

Environmental Protection

Agency

Air and Radiation EPA420-F-99-008

March 1999

Office of Mobile Sources

New Phase 2 Standards for Small

Spark-Ignition Nonhandheld Engines

History of Rulemaking

In July 1995, EPA finalized the first federal regulations affecting small

nonroad SI engines at or below 19 kilowatts (kW), or 25 horsepower.

The regulations, commonly known as “Phase 1,” took effect for most

new handheld and nonhandheld engines beginning in model year 1997

and are expected to result in a 32 percent reduction in hydrocarbon (HC)

emissions from these engines. (See Table 1 for examples of small

nonroad SI engines.)

The U.S. Environmental Protection Agency (EPA) is setting stringent

new Phase 2 emission standards for nonroad small spark-ignition (SI)

nonhandheld engines that will reduce hydrocarbons plus oxides of

nitrogen (HC+NOx) by an additional 59 percent beyond the current

Phase 1 standards. The adopted rule includes provisions that give

industry flexibility and ease the transition to the more stringent Phase 2

program, especially for small volume engine and equipment

manufacturers. The new standards will be phased in between 2001 and

2007.
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Table 1. Small SI Engine Classes

In September 1993, the Agency initiated a regulatory negotiation to

develop a framework for a “Phase 2” rule. This process ended in February 1996 without a consensus among all the participants on a Phase 2

program. However, EPA continued to work with several former

regulatory negotiation members.

In March of 1997, EPA published an Advance Notice of Proposed

Rulemaking (ANPRM) announcing the Agency’s intent to issue a

proposed rule which would cover both handheld and nonhandheld

engines. This ANPRM also published the text of two Statements of

Principles (SOPs) which were developed between EPA and other interested parties in 1996. In January of 1998, the Agency published a Notice

of Proposed Rulemaking (NPRM) for the Phase 2 regulations for small

SI engines.

Based on the public comments EPA received on the NPRM, this final

rule for nonhandheld engines adopts emission standards considerably

more stringent than those proposed for Class I nonhandheld engines, as

well as compliance program provisions reflecting closer harmonization

with those required by the State of California.

In addition, there have been rapid advances in emission reduction technologies for handheld engines since the publication of the NPRM. EPA

has very recently received information which could potentially support

handheld standards much more stringent than those originally proposed.

In light of this new information, which addresses a new technology that

EPA did not analyze at the NPRM stage, and in the interest of providing

an opportunity for public comment on more stringent levels for
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handheld engine emission standards, Phase 2 regulations for handheld

engines (such as trimmers, brush cutters, and chainsaws) will be addressed in a separate Supplemental Notice of Proposed Rulemaking

(SNPRM) in June of 1999, with a final rule in March of 2000.

Overview of the Final Rule

This final rule adopts emission standards and other regulatory requirements only for Class I and II engines as used in nonhandheld equipment

applications. The adopted Phase 2 program for nonhandheld engines is

expected to result in a shift to cleaner, more durable engine technology.

Notably, the Phase 2 program will lead to increased use of automotivestyle overhead valve (OHV) technology in nonhandheld engines. In

addition, these Phase 2 rules include new programmatic requirements to

ensure that engines meet the tighter standards throughout the useful life

of the equipment. Highlights of the final rule include:

• Tighter emission standards for HC+NOx ( in grams per kilowatt-hour

(g/kW-hr) to be phased-in over a number of years, allowing the manufacturers an orderly and efficient transition of engine designs and

technologies from those complying with the existing Phase 1 standards

to those necessary to meet the Phase 2 requirements.

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Table 2. Phase 2 HC+NOx Emission Standards for Nonhandheld

Engines

• Three useful life categories for nonhandheld engines to account for

widely varying product lives.

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Table 3. Useful Life Categories for Nonhandheld Engines (hours)
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• A compliance program to ensure engines continue meeting the standards for the useful life of the engine, including certification, production line testing, and in-use testing.

Health and Environmental Benefits

EPA’s primary reason for controlling emissions from small SI

nonhandheld engines is the role of their HC emissions in forming ozone,

a significant component of smog. Of the major air pollutants for which

National Ambient Air Quality Standards (NAAQS) have been designated

under the Clean Air Act, the most widespread problem continues to be

ozone. The Phase 2 nonhandheld engine standards should result in a 59

percent reduction in HC + NOx emissions from these engines beyond

the 32 percent reduction expected from the Phase I standards. This is

equivalent to an annual reduction of 390,000 tons of HC+NOx emissions

by year 2027. In addition, this reduction in HC + NOx emissions will be

accompanied by an overall reduction in fuel consumption.

Small SI engines produce approximately one tenth of U.S. mobile source

HC emissions and are the largest single contributor to nonroad HC

inventories. Thus, the final Phase 2 standards would help the States in

their progress towards compliance with the National Ambient Air Quality Standards for ozone.

The final standards will generate significant reductions in emissions

from these engines at very low costs. When fuel savings are considered,

costs are lower and a net savings may actually result for some larger

nonhandheld engines.

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Table 4. Engine Yearly Fuel Savings and Resultant Cost Per Engine

The technological changes necessary to bring these engines into compliance with the emission standards will cause a decrease in fuel consumption of approximately 15 percent for nonhandheld Class I and II sidevalve (SV) engines. For Class I and II engines, EPA assumes that there

will be fuel savings as SV engines are phased-out and replaced with

more fuel efficient overhead-valve (OHV) engines. The high savings per

equipment in Class II are influenced by the fact that the engines in this

class are utilized for longer hours compared to the equipment in Class I.
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Table 5. Cost Effectiveness of Phase 2 Nonhandheld Engine Final

Rule

Effect on Industry

The final rule will require engine manufacturers to:

• build cleaner, more durable engines; and

• certify that those engines will met standards for their full regulatory

useful lives.

One of the technology changes available to achieve these standards

(adopting an overhead-valve configuration) has already been done on

some Class I engines and is also anticipated to be a primary choice for

manufacturers of Class II engines to meet their Phase 2 emission levels.

The rule will not require the use of catalysts for any group of engines.

The final rule includes provisions to ease the transition from Phase 1 to

the Phase 2 program, to ensure that the Phase 2 standards are costeffective and achievable, and to minimize the compliance burden while

maintaining the environmental benefits of the rule. These provisions

include phase-in schedules, a certification averaging, banking, and

trading program, special compliance provisions for very low emitting

engines, and special provisions to ease and/or delay the impact of the

rule on low volume engines and equipment.

For More Information

Additional documents on this small nonroad SI engines are available

electronically from the EPA Internet server at:

 http://www.epa.gov/oms/equip-ld.htm

Document information is also available by writing to:

 U.S. Environmental Protection Agency

 Office of Mobile Sources

 2000 Traverwood Drive

 Ann Arbor, MI 48105

 (734) 214-4278