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Regulatory

Announcement

 Printed on Recycled Paper

United States

Environmental Protection

Agency

Air and Radiation EPA420-F-97-045

December 1997

Office of Mobile Sources

Proposed Phase 2 Standards for

Small Spark-Ignition 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 HC emissions

from these engines. Handheld engines are used in equipment such as

chain saws, string trimmers and leaf blowers. Examples of equipment

using nonhandheld engines include lawn mowers, garden tractors, tillers

and certain construction equipment.

The U.S. Environmental Protection Agency (EPA) is proposing Phase 2

standards for nonroad small spark ignition (SI) engines that will reduce

hydrocarbons plus oxides of nitrogen (HC+NOx) by an additional 30

percent beyond the current Phase 1 standards. The proposed 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 would be

phased in between 2001 and 2005.
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This “Phase 2” proposed rule follows several years of negotiations

between EPA, engine manufacturers and environmental groups. The

proposal is based closely on two Statements of Principles (SOPs) signed

by EPA and industry groups. EPA published an Advance Notice of

Proposed Rulemaking in March 1997 which announced the signing of

the two SOPs and requested comments on all aspects of the SOPs for

purposes of developing the proposed rule. As a result of a suit by the

Sierra Club, EPA is under a court-ordered deadline to complete a final

Phase 2 rule for these engines by December 23, 1998.

While EPA’s and California’s Phase 1 standards for these engines were

essentially the same, California (because of its unique air quality problems) is pursuing a second phase of standards that would be substantially

tighter than EPA’s.

Overview of Proposed Rule

The proposed Phase 2 program is expected to result in a shift to cleaner,

more durable engine technology. Notably, the Phase 2 program will lead

to increased use of automotive-style overhead valve (OHV) technology

in nonhandheld engines. In addition, the proposal includes new programmatic requirements to ensure that engines meet the tighter standards

throughout the useful life of the equipment. Highlights of the proposed

rule include:

• Tighter emission standards for HC+NOx (in grams per kilowatthour (g/kW-hr)) to be phased-in during model years 2001 through 2005.

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2002raeY

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3002raeY

ledoM

4002raeY

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C 0 Issal 2 0 5. 2 0 5. 2 0 5. 2 0 5. 25.

C 0 lass II 1 6 8. 1 0 6. 1 6 5. 1 1 3. 12.

Table 1: Small SI Engine Classes

N d onhandheld Handhel

C I lass I C I lass I C V lass II C V lass I Class

<225 cc ≥2 c 25 cc < c 20 c 20 c ≤XX<50 cc ≥50 cc
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(When compared to Phase 1 standards, Phase 2 standards may not appear

more stringent in all cases. This is because Phase 1 standards are ‘new

engine’ standards and Phase 2 standards are in-use standards)

• Three useful life categories for nonhandheld engines and two useful

life categories for handheld engines to account for widely varying

product lives.

• 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 principle reason for controlling emissions from small SI engines is

the role of their HC emissions in forming ozone, a primary component

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C 0 lass III, IV and V 5 0 30

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C B Cyrogeta C A ategory Category

C 6 lass I 6 0 2 0 5 50

C 0 lass II 2 0 5 5 0 0 100

Table 3: Phase 2 HC+NOx Emission Standards for Handheld Engines

(in g/kW-hr) Showing Phase-in by Percentage of Production

Engine

Class

HC+NOx

Emission

Standard

Model

Year 2002

Model

Year 2003

Model

Year 2004

Model

Year 2005

C 0 lass III 21

2 % 0% 4 % 0 7 % 0 100 C 2 lass IV 17

C 6 lass V 11
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of smog. The Phase 2 standards should result in a 30 percent reduction in

HC+NOx emissions from these engines beyond the 32 percent reduction

expected from the Phase 1 standards. This is equivalent to an annual

reduction of 135,000 tons of HC+NOx emissions by the time a complete

fleet turnover occurs in 2025. This reduction in HC+NOx emissions will

be accompanied by an estimated overall reduction in fuel consumption

of about 9 percent.

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 proposed Phase 2 standards would help the States

in their progress towards compliance with the National Ambient Air

Quality Standards for ozone.

The proposed standards will generate significant reductions in emissions

from these engines at very low costs. Further, they will result in fuel

economy improvements which will offset much of the costs of the

emission reductions.

Effect On Industry

The proposed regulation will require engine manufacturers to:

• build cleaner, more durable engines;

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

useful lives; and

• conduct testing of in-use engines to prove their performance in-use.

The Phase 2 standards will drive virtually all larger (Class 2)

nonhandheld engines to the use of OHV technology. This will improve

the emission durability and fuel economy of these engines. (A trend

toward overhead valves is already underway for these engines.) For

other categories of engines, the standards will require improvements to

existing engine design, but will not require major technological changes.

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

The proposed 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

EPA’s principle

reason for controlling emissions from small

SI engines is the

role of their HC

emissions in

forming ozone, a

primary component of smog.
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trading program for nonhandheld engines, 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.

The cost of meeting the tighter standards are expected to range from less

than a dollar per engine for smaller, lower priced engines, to approximately $18 for larger, more expensive engines. When fuel savings are

considered, costs are lower and a net savings may actually result for

some larger nonhandheld engines.

Public Participation Opportunities

EPA desires full public participation in arriving at final rulemaking

decisions. The Agency solicits comments on all aspects of the proposal

from all interested parties. Wherever applicable, full supporting data and

detailed analysis should also be submitted to allow EPA to make maximum use of the comments. Commenters are especially encouraged to

provide specific suggestions for changes to any aspects of the proposal

that they believe need to be modified or improved. A public hearing will

also be held on February 11, 1998 beginning at 10:00am in Ypsilanti,

Michigan. For additional information on the public hearing, please call

(734) 668-4334.

For instructions on submitting written comments, please see the Federal

Register notice published on January 27, 1998. It is available from the

EPA Air and Radiation Docket by calling 202-260-7548; please refer to

Docket No. A-96-55. In addition, the proposed rule is available electronically via the EPA Internet server at:

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

For More Information

Additional documents on small nonroad SI engines are available electronically at

the Internet site given above, or by contacting Russ Banush at:

U.S. Environmental Protection Agency

Office of Mobile Sources

2565 Plymouth Road

Ann Arbor, MI 48105

734-668-4333