EPA Bonding Resources. EPA has prepared a Bond Requirements Fact Sheet that has a sample bond form attached to it. There is also a Bond Worksheet that each manufacturer will need to fill out and attach to the first application for certification for that manufacturer in a given model year.

Small Engine Regulations

• Summary of EPA Regulations
• Emission Standards for Small Engines
• How to Comply with the Phase 3 Regulations
• Averaging, Banking, and Trading
• Emission Warranty Requirements
• Bond Requirements
• Importer Responsibilities
• State Regulations
• More Resources

Introduction

This web page provides a summary of the United States environmental regulations for small spark ignition engines (≤19 kilowatts or 25 horsepower).  These engines are used in applications such as lawnmowers, chain saws, generators, and similar equipment.  The information is provided for foreign manufacturers and importers who want to export equipment containing these engines to the United States.

The United States is very concerned about air pollution because of the health effects it causes.  This includes respiratory problems, heart disease and cancer.  The U.S. Environmental Protection Agency (EPA) is responsible for writing regulations that limit the amount of air pollution from various sources, including small engines. 

In addition to federal EPA regulations, the State of California has implemented regulations that affect small engines sold in that state.

Summary of EPA Regulations

Small engines are classified by EPA by size, and according to whether they are handheld or non-handheld. Table 1 shows EPA’s classification scheme.

Typical applications for the nonhandheld categories include:

• Class I engines are used primarily in walk-behind lawnmowers.
• Class II engines are used primarily in lawn and garden tractors.

The handheld categories include:

• Class III and IV engines are used primarily in residential equipment such as string trimmers, leaf blowers and small chainsaws.
• Class V engines are used primarily in commercial equipment such as large chainsaws.

Definitions for handheld and nonhandheld engines and other technical terms are published in the regulations (see 40 CFR 90.3 and 40 CFR 90.102 and 40 CFR 1054.801).

The small engine air pollution regulations include specific emission standards for each class of small engines and procedures that must be followed by manufacturers and importers to assure that the standards are met over the useful life of the equipment.  The regulations also include provisions that give manufacturers some flexibility in how they meet these EPA air pollution standards.

The air pollution regulations for small engines were developed in three phases. The regulatory dates for all phases have passed and all rules are now in effect:

• Phase 1 (July 1995) introduced an initial level of emission standards for both handheld and non-handheld equipment and a certification process. The rule set allowable exhaust levels for hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) and it applied to all small engines produced after September 1, 1997 (with some earlier and a few later, depending on type). Allowable Phase 1 emission levels vary, depending on engine size and use.

• Phase 2 (March 1999, April 2000) included tighter emission standards for engines used in handheld equipment applications for HC+NOx (in grams per kilowatt-hour (g/kW-hr)). The standards were phased in over several years, to give the manufacturers time for an orderly and efficient transition of engine designs. In addition, the Phase 2 rule included new requirements to ensure that engines meet the tighter standards throughout the useful life of the equipment.

• Phase 3 (September 2008) for exhaust emission standards for HC+NOx were lowered to 10 g/kW-hr for Class I engines starting in the 2012 model year, and 8 g/kW-hr for Class II engines starting in the 2011 model year.  Most manufacturers met these standards by improving engine combustion and by adding catalytic converters. These standards were consistent with the requirements previously adopted by the California Air Resources Board (see State Initiatives below). With Phase 3, EPA did not change exhaust emission standards for handheld engines. However, they did add evaporative emission standards for both handheld and nonhandheld equipment that included requirements to control fuel tank permeation, fuel line permeation, and diffusion emissions.  For nonhandheld engines, EPA required control of running losses.  Also in Phase 3 regulations are specific provisions for emission control equipment warranties and a bond requirement.

Before a small engine can be imported into the U.S., it must be certified and labeled:

• In order to be certified, test data must be submitted to EPA, together with other information demonstrating that the engine meets applicable standards.
• Before importation, each certified engine must be labeled to indicate compliance with the rules.

If an engine is not labeled, the engine is presumed by U.S government agencies to be uncertified. Therefore, the engine may not be imported into the U.S.

Ordinarily, the engine manufacturer, not the importer, obtains EPA certification for imported engines. However, an engine importer also may apply to EPA for a certificate, on the condition that the importer assumes all the responsibilities of the manufacturer.

Emission Standards for Small Engines

A summary of the exhaust emission standards for small engines is shown in Table 2. 

For Class I small engines, standards allowed different levels of emissions depending on the size of the engine. When Phase 3 standards became effective in model year 2012, only one set of emission standards applied to Class I engines.  Phase 3 emission standards for Classes II, III, IV and V applied starting in model year 2011.

Table 2. Exhaust Emission Standards in Grams per Kilowatt-hour (g/kW-hr)

HC = hydrocarbons
NOx = oxides of nitrogen
CO = carbon monoxide
HC + NOx standards for Class II engines are for years 2005 or later.  HC + NOx standards for handheld engines are for years 2007 or later.  Previous years may have higher pollutant levels.
Source: 40 CFR 90.103 and 40 CFR 1054.103.

Engines are required to meet exhaust emission standards over their full useful life, which is five years or a number of hours of operation, whichever comes first.  EPA has established a procedure and requirements for determining useful life periods.  For more information on useful life periods, see 40 CFR 1054.107.

In addition to exhaust emission standards, the Phase 3 regulations also include emission standards for evaporative losses from the fuel system for both handheld and nonhandheld equipment.  The evaporative standards include:

• fuel line permeation,
• tank permeation, and
• running loss (nonhandheld only).

Evaporative emission standards apply starting in different years, depending on the type of equipment and other factors.  For more information on evaporative emission standards, see 40 CFR 1054.110.

How to Comply with the Phase 3 Regulations

The following is a brief summary of the compliance steps necessary to import a small engine into the U.S. under the Phase 3 regulations.  The complete set of regulations is available in English at 40 CFR 1054.

1. Manufacturers must divide their products into groups of engines called “engine families”. Each engine family is composed of engines having identical physical characteristics and similar emissions characteristics. For more information on selecting engine families see CFR 1054.230.

2. Before the applicable engine is imported into the U.S, manufacturers must obtain a certificate of conformity from EPA for each engine family, and for every model year.  To apply for a certificate of conformity, an applicant must:

• Conduct emissions testing of selected engines using the test procedure specified by EPA. (The testing information is found in 40 CFR 1054.235).  Engine manufacturers are required to evaluate the emissions of engines, and take into account how the performance of the emission control system is expected to deteriorate over the expected useful life of the engine.  Useful life periods for engines are established by EPA, and range from 50 to 1,000 hours, depending on the application.  Useful life categories are published in the regulations (see 40 CFR 1054.107).
• Document other information about the engine, such as its physical characteristics and how the emission control system operates.
• Prepare a certification that states that all engines in the engine family comply with the regulations.
• Submit an application to EPA along with emission testing results, other information and your certification (see 40 CFR 1054.205 for complete application requirements).

If the engine results show that emissions are at or below standards, and if all other information is correctly provided, EPA will issue a certificate of conformity.  If certification is denied, EPA will provide a written explanation.

3. The engine manufacturer must affix a permanent certification label to the engine at the time it is manufactured.   (For more information on labeling see 1054.135).

4. Perform continual testing of production-line engines.  Statistical formulas provided by EPA must be used to determine the required number of production line tests.  Tests results must be sent to EPA. (For more information on production-line testing see 40 CFR 1054 Subpart D.)

5. Maintain records including your application, engineering data and results of emission control tests.  Provide records to EPA, if requested.  (For more information on record keeping see 40 CFR 1054.250).

6. Post a bond to cover and potential compliance or enforcement actions or demonstrate to EPA in your application for certification that you are able to meet any potential compliance or enforcement related obligations. For more information on bonding requirements see 40 CFR 1054.690.

7. Complete EPA Form 3520-21.  This form must be prepared by the importer for each imported engine.

Averaging, Banking and Trading

To give manufacturers flexibility in meeting the exhaust and evaporative standards for small engines, EPA allows averaging, banking and trading:

• Averaging applies only to manufacturers that make more than one engine family.  Averaging allows a manufacturer to certify engine families based on the average emissions over all of the manufacturer’s families, in a given model year.  Thus if one or more engine families are above the applicable emission standard but another engine family is certified below the same emission standard, and if the emissions averaged over all of the manufacturer’s families are at or below the level of the emission standard, the manufacturer can certify all of the families.  (For more information on averaging, see 40 CFR 90.204 for Phases 1 and 2 and 40 CFR 1054.710 for Phase 3).
• Banking allows an engine manufacturer to retain credits for one model year, and use them for averaging or trading in a future model year.  (For more information on banking, see 40 CFR 90.205 for Phases 1 and 2 and 40 CFR 1054.715 for Phase 3).
• Trading allows different engine manufacturers to exchange of emission credits among themselves.  The credits can then can be used for averaging purposes, banked for future use, or traded to another engine manufacturer.  (For more information on trading, see 40 CFR 90.206 for Phases 1 and 2 and 40 CFR 1054.720 for Phase 3).

Emission Warranty Requirements

Under Phase 3 regulations manufacturers must warranty their exhaust emission control system for at least two years unless otherwise allowed by EPA or 50 percent of the useful life of engines equipped with hour meters.  The emission-related warranty must cover all components whose failure would increase an engine’s emissions of any regulated pollutant.  Additionally, to assure that equipment owners will be able to promptly obtain warranty repairs, manufacturers must:

• provide an monitor a toll-free telephone number and an email address for owners to receive information about warranty claims and repairs;
• provide a source of replacement parts in the U.S.; and
• fulfill EPA’s minimum service center requirements or post a bond.

This warranty is separate and apart from any other manufacturer warranty.  For more information on warranty requirements see 40 CFR 1054.120.

Bond Requirements

Staring on January 1, 2010, before importing certified engines into the U.S., manufacturers must post a bond to cover any potential compliance or enforcement actions unless the manufacturer is able to demonstrate to EPA that they are able to meet potential compliance or enforcement obligations.  For more information on compliance bonding requirements see 40 CFR 1054.690.

Manufacturers must also post a bond to cover emission control warranty obligations unless they have a sufficient number of authorized repair facilities in the U.S.  EPA has established specific criteria for making this determination.  For more information on warranty bonding requirements see 40 CFR 1054.120(f)(4).

A single bond may be posted to meet both the compliance and warranty bonding requirements.

Importer Responsibilities

Along with the manufacturer the importer is responsible for ensuring that small engines imported to the United States comply with all certification standards and requirements:

• Importers are prohibited from importing small engines that are not EPA-certified and labeled.  (EPA highly recommends that importers inspect the engines they intend to import to verify that they are EPA-certified and labeled.)  
• Importers are responsible for ensuring that the small engine manufacturer will honor the emissions warranty.
• The importer bears responsibility for any requirements not met by the original engine manufacturer.
• The importer must complete EPA Declaration Form 3520-21, which requires confirmation of EPA certification or a description of the applicable exemption. Form 3520-21 must be submitted to CBP upon request along with other CBP entry documents.
• Importers must keep the forms for five years and make them available promptly upon request.

For more information on importing see: https://www.epa.gov/importing-vehicles-and-engines/learn-about-importing-vehicles-and-engines

State Regulations

With regard to small engine air pollution regulations, only the state of California has developed its own rules.  In all other states, the federal EPA regulations are the only rules that apply.  The California standards are either the same as, or are more stringent than the corresponding federal EPA standards.

California has established two tiers of requirements for small engines sold in that state:

• Tier I was implemented in 1995.  It regulates emissions of hydrocarbons, NOx, particulate matter, and CO to varying degrees, based on the displacement of the engine.
• Tier II became effective for model year 2000, and will continue to regulate hydrocarbons, NOx, particulate matter, and CO emissions through 2010.
• Tier II also established durability requirements for emissions-control systems. Engine manufacturers must demonstrate that the equipment's emissions levels remain low for periods ranging from 50 hours to 500 hours, depending on the displacement of the engines and whether the equipment is residential or commercial.

California also has evaporative emissions performance and design standards for gasoline-fueled, spark-ignited small engines rated at equal to or less than 19 kilowatts, and equipment utilizing such engines.  The standards apply to applicable engines model years 2006 through 2013.  Engine manufacturers may opt to comply with either the emissions or design standards.  (For more information, see California’s small off-road engine (SORE) program).

More Resources

Importing Vehicles and Engines.  Information and points of contact for importers.

Engine Certification Data. These pages provide certification data from various engine manufacturers and vehicle manufacturers for past and current model years.

Lawn and Garden (Small Gasoline) Equipment. A summary of EPA rulemaking with regard to small spark-ignition engines.

Nonroad engines, equipment and vehicles.  Technical information provide by EPA covering nonroad engines.

Nonroad Confirmatory Testing for Small Spark-Ignition (SI) and Compression-Ignition (CI) Engines. This document includes the steps for nonroad confirmatory testing for small spark-ignition (SI) and nonroad compression-ignition (CI) engines at EPA's National Vehicle and Fuel Emissions Laboratory (NVFEL).

40 CFR Part 90: Control of Emissions from Nonroad Spark-Ignition Engines at Or Below 19 Kilowatts. Codified rules pertaining to emissions from nonroad spark-ignition engines at or below 19 kilowatts.