# Control of Emissions of Air Pollution From 2004 and Later Model Year Heavy-Duty Highway Engines and Vehicles; Revision of Light-Duty Truck Definition > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A99-26795 ## Record - **Collection:** Federal Register - **Document type:** Proposed Rule - **Published:** October 29, 1999 - **Citation:** 64 FR 58472 ## Text SUMMARY: We are proposing to take several actions relating to emission standards and test procedures for heavy-duty engines and vehicles intended for operation on roads and highways. The proposed provisions are for the 2004 and later model years. First, we are proposing new more stringent emissions standards and related provisions for all heavy-duty Otto-cycle (e.g., gasoline-fueled) engines and vehicles. Vehicles in this category include large full size pick-up trucks, full size cargo and passenger vans, and the largest sport utility vehicles. For heavy-duty Otto-cycle engines and vehicles, today's proposal would reduce the standards for oxides of nitrogen and hydrocarbons by approximately 75 percent from current standards. Second, we propose to reaffirm that the NMHC+NOX standard promulgated in October, 1997 for diesel heavy-duty engines is both necessary and feasible. This standard represents about a 50 percent reduction in emissions of nitrogen oxides, as well as reductions in hydrocarbons, from diesel trucks and buses. Third, we are proposing to require on-board diagnostics systems for all heavy-duty vehicles and engines at or below 14,000 lbs gross vehicle weight rating (GVWR), and to revise the on- board diagnostics requirements for diesel light-duty vehicles and trucks. These systems will identify the failure of components of the emissions control system. Fourth, we are proposing the addition of new test procedures and associated standards for heavy-duty diesel engines and vehicles. Fifth, we are proposing to include heavy models of gasoline and diesel-fueled sport-utility vehicles and similar heavy- duty vehicles used primarily for personal transportation in the Tier 2 program that EPA proposed earlier this year. Today's proposal would result in lower emissions of oxides of nitrogen and hydrocarbons, as well as lower particulate matter due to reductions in secondary particulate formation (secondary particulate matter is not emitted directly from the engine, but is formed when emissions of oxides of nitrogen react with ammonia in the atmosphere to produce ammonium nitrate particulates), and would assist states and regions facing ozone air quality problems that are causing a range of adverse health effects, particularly respiratory impairment and related illnesses. DATES: We must receive your comments on this NPRM by December 2, 1999. A public hearing will be held on November 2, 1999 (EPA has published notice of this hearing on October 22, 1999 (64 FR 56985).). EPA requests that parties who want to testify notify the contact person listed in the ADDRESSES section of this document one week before the date of the hearing. More information about commenting on this action and on the public hearing may be found in section XI What are the Opportunities for Public Participation? ADDRESSES: Written comments should be submitted (in duplicate, if possible) to: EPA Air and Radiation Docket, Attn: Docket No. A-98-32, Room M-1500 (Mail Code 6102), 401 M Street SW, Washington, DC 20460. EPA requests that a copy of the comments also be sent to the contact person listed below. Materials relevant to this proposal have been placed in Docket Nos. A-98-32 and A-95-27 and may be viewed in Room M- 1500 between 8:00 a.m. and 5:30 p.m., Monday through Friday. The telephone number is (202) 260-7548 and the facsimile number is (202) 260-4400. A reasonable fee may be charged by EPA for copying docket materials. The public hearing will be held at Top of the Tower, 1717 Arch Street, 51st Floor, Philadelphia, PA 19103, telephone: 215-567-8787, fax: 215-557-5171. FOR FURTHER INFORMATION CONTACT: Margaret Borushko, U.S. Environmental Protection Agency, Engine Programs and Compliance Division, 2000 Traverwood Drive, Ann Arbor, MI 48105-2498. Telephone (734) 214-4334; Fax (734) 214-4816; e-mail [email protected]. SUPPLEMENTARY INFORMATION: Regulated Entities Entities potentially regulated by this action are those that manufacture and sell new heavy-duty motor vehicles, new heavy-duty engines, and new diesel light-duty motor vehicles in the United States. Regulated categories and entities include: ------------------------------------------------------------------------ Category Examples of regulated entities ------------------------------------------------------------------------ Industry............................... Manufacturers of new heavy-duty motor vehicles and engines. Manufacturers of new diesel light-duty motor vehicles and engines. ------------------------------------------------------------------------ This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated by this action. This table lists the types of entities that EPA is now aware could potentially be regulated by this action. Other types of entities not listed in the table could also be regulated. To determine whether your activities are regulated by this action, you should carefully examine the applicability criteria in Secs. 86.001-1 and 86.1801-01. If you have questions regarding the applicability of this action to a particular entity, consult the person listed in the preceding FOR FURTHER INFORMATION CONTACT section. Obtaining Rulemaking Documents Through the Internet The preamble, regulatory language, regulatory impact analysis, and other related documents are also available electronically from the EPA Internet Web site. This service is free of charge, except for any cost you already incur for Internet connectivity. The electronic version is made available on the day of publication on the primary Web site listed below. The EPA Office of Mobile Sources also publishes Federal Register notices and related documents on the secondary Web site listed below. 1. http://www.epa.gov/docs/fedrgstr/EPA-AIR/ (either select desired date or use Search feature) 2. http://www.epa.gov/OMSWWW/ (Look in What's New or under the specific rulemaking topic) Please note that due to differences between the software used to develop the document and the software into which the document may be downloaded, changes in format, page length, etc. may occur. Table of Acronyms and Abbreviations ------------------------------------------------------------------------ ------------------------------------------------------------------------ ABT Averaging, Banking, and Trading AECD Auxiliary Emission Control Device ALVW Adjusted Loaded Vehicle Weight ANPRM Advance Notice of Proposed Rulemaking BSFC Brake-Specific Fuel Consumption CAA Clean Air Act CAP 2000 Compliance Assurance Program for the 2000 and later model years CARB California Air Resources Board [[Page 58473]] CASAC Clean Air Scientific Advisory Committee CFF Clean Fuel Fleet CO Carbon Monoxide DF Deterioration Factor DOC Diesel Oxidation Catalyst DRI Desert Research Institute EGR Exhaust Gas Recirculation EMA Engine Manufacturers Association EPA Environmental Protection Agency FEL Family Emission Limit g/bhp-hr grams per brake-horsepower hour g/mi grams per mile GVWR Gross Vehicle Weight Rating HC Hydrocarbons HD Heavy-Duty HDDE Heavy-Duty Diesel Engine HDE Heavy-Duty Engine HDEWG Heavy-Duty Engine Working Group HDV Heavy-Duty Vehicle HEUI Hydraulically Actuated Electronic Unit Injection HLDT Heavy Light-Duty Truck LDT Light-Duty Truck LDV Light-Duty Vehicle LEV Low Emission Vehicle LLDT Light Light-Duty Truck LRT Load Response Test MDV Medium-Duty Vehicle MEUI Mechanically Actuated Electronic Unit Injection MIL Malfunction Indicator Light MY Model Year NAAQS National Ambient Air Quality Standards NCP Non-Conformance Penalty NMHC Non-Methane Hydrocarbon NMOG Non-Methane Organic Gas NOX Nitrogen Oxides NPRM Notice of Proposed Rulemaking OBD On-Board Diagnostics OEM Original Equipment Manufacturer ORVR Onboard Refueling Vapor Recovery PM Particulate Matter PM10 Particulate Matter of 10 microns or less in diameter PM2.5 Particulate Matter of 2.5 microns or less in diameter RIA Regulatory Impact Analysis SIP State Implementation Plan SOP Statement of Principles TW Test Weight UDDS Urban Dynamometer Driving Schedule ULEV Ultra Low Emission Vehicle VGT Variable Geometry Turbocharger VMT Vehicle Miles Traveled VNT Variable Nozzle Turbocharger VOC Volatile Organic Compound ------------------------------------------------------------------------ Table of Contents I. What is EPA Proposing to Do? A. Changes to the Engine-Based Program B. Expanding the Otto-cycle Vehicle-based Program to Certain Heavy- duty Vehicles C. Additional Changes Affecting Heavy-duty Vehicle and Heavy-duty Engine Programs D. Heavy-duty Lead Time Issues and Voluntary Federal Standards II. What is the Environmental Need for this Proposal? A. Need for Additional NOX and NMHC Reductions 1. Health and Welfare Effects from NMHC and NOX 2. Current Compliance with the Ozone NAAQS 3. Future Compliance with the Ozone NAAQS 4. Contribution of HD Diesel and Gasoline Engines to Total VOC and NOX Inventories B. Need for Additional PM Reductions 1. Health and Welfare Effects from PM 2. Current and Future Compliance with the PM10 NAAQS 3. Contribution of HD Diesel and Gasoline Vehicles to PM Inventories a. Contribution to National PM10 Inventories b. Source-apportionment Studies for Diesel PM C. Air Toxics from HD Engines and Vehicles III. What is the Important Background Information for this Proposal? A. Statement of Principles and Rulemaking History B. 1999 Review of Heavy-duty Diesel Engine NMHC+NOX Standards C. Proposal for Heavy-duty Gasoline Engine Standards 1. Summary of Comments on 1996 NPRM 2. Analysis Leading to Decision to not Finalize Otto-cycle Standards D. Consent Decrees with Heavy-duty Diesel Engine Manufacturers IV. What are the Details of this Proposal? A. Reaffirmation of 2004 NMHC + NOX Standard for Heavy- duty Diesel Engines B. Are Changes in Diesel Fuel Quality Necessary to Meet the 2004 Standards? C. Otto-cycle Engine-based Program 1. Engine Exhaust Emissions Standards 2. Averaging, Banking, and Trading for Otto-Cycle Engines D. Supplemental Exhaust Emission Standards and Test Procedures for HD Diesel Engines 1. Introduction/Background 2. Proposed Supplemental Test Procedures and Standards a. Supplemental Steady-State Test b. Not-To-Exceed Limits c. Diesel Supplemental Load Response Test d. Ambient Conditions, Temperature and Humidity, Laboratory and In-use Testing 3. Access to On-board Computer Information E. Otto-cycle Vehicle-based Program 1. Moving to a Vehicle-based Test Procedure and Standards 2. Vehicle Exhaust Emissions Standards 3. Heavy-duty Vehicle Averaging, Banking and Trading a. Background b. Proposal c. Credit exchanges between the engine and chassis-based programs 4. Evaporative standards/onboard refueling vapor recovery a. Enhanced evaporative emissions b. Onboard refueling vapor recovery 5. Compliance Assurance Program a. CAP 2000 for HDVs b. Proposed Modifications to the CAP 2000 Program For Chassis- Based HDVs 6. Useful Life 7. Aftermarket Alternative Fuels Conversions F. Proposal to Revise the Definition of Light-duty Truck 1. Background 2. Proposal 3. Integration into Proposed Tier 2 Program a. Tier 2 Standards for New HLDTs b. Interim Standards for New HLDTs c. Technological Feasibility of Tier 2 Standards for New HLDTs G. On-Board Diagnostics 1. Background on OBD 2. CARB OBDII Requirements 3. Proposed Federal OBD Requirements 4. Federal OBD Malfunction Thresholds and Monitoring Requirements 5. Proposed Standardization Requirements 6. Deficiency Provisions 7. Applicability and Waivers 8. Certification Provisions H. Durability Procedures I. Non-Conformance Penalties V. Additional Heavy-Duty Engine Provisions Under Consideration A. Revision to the Definition of Rated Speed B. A Manufacturer-based In-use Testing Program for Heavy-duty Engines C. On-board Diagnostics for Heavy-duty Engines and Vehicles Above 14,000 Pounds GVWR D. Applying the Not-to-Exceed Approach and Emission Limits to Heavy- duty Otto-cycle Engines VI. Are the Proposed Requirements Technologically Feasible? A. 2004 Emission Standards for Heavy-duty Diesel Engines 1. Probable Emission Control Strategies 2. Feasibility of 2004 HD Diesel Standards B. 2004 Emission Standards for Heavy-duty Otto-cycle Vehicles and Engines 1. Current Technologies 2. Chassis-based standards 3. Engine-based standards 4. Onboard Refueling Vapor Recovery C. On-Board Diagnostics VII. What are the Environmental Benefits of this Proposal? A. 2004 Emission Standards for Heavy-Duty Diesel Engines B. 2004 Emission Standards for Heavy-duty Otto-cycle Vehicles and Engines C. Benefits of the Supplemental Standards and In-Use Control Measures of Today's Proposal VIII. What are the Economic Impacts of the Proposal? A. 2004 Emission Standards for Heavy-duty Diesel Engines 1. Expected Technologies 2. Per Engine Costs 3. Aggregate Costs to Society B. 2004 Emission Standards for Heavy-duty Otto-cycle Vehicles and Engines 1. Expected Technologies 2. Per Vehicle Costs 3. Aggregate Cost to Society [[Page 58474]] IX. What is the Cost-Effectiveness of the Proposal? A. 2004 Emission Standards for Heavy-duty Diesel Engines B. 2004 Emission Standards for Heavy-duty Otto-cycle Vehicles and Engines X. Are Future Reductions in HD Emissions Possible? A. Potential Future Standards for Heavy-duty Diesel Vehicles and Engines 1. Potential Future Reductions in Heavy-duty Diesel NOX and NMHC 2. Potential Future Reductions in Heavy-duty Diesel Engine PM 3. Potential Structure of Future Diesel Emission Standards B. Potential Future Standards for Heavy-duty Otto-cycle Vehicles 1. Exhaust Emission Standards 2. Evaporative standards XI. What are the Opportunities for Public Participation? A. Comments and the Public Docket B. Public Hearing XII. What Administrative Requirements Apply to this Proposal? A. Compliance with Executive Order 12866 B. Impact on Small Entities C. Unfunded Mandates Reform Act D. Reporting and Recordkeeping Requirements E. Compliance with Executive Order 13045 F. Enhancing Intergovernmental Partnerships G. Consultation and Coordination with Indian Tribal Governments H. National Technology Transfer and Advancement Act I. Compliance with Executive Order on Federalism XIII. What is EPA's Statutory Authority for this Proposal? I. What Is EPA Proposing To Do? EPA (or, ``the Agency'') is proposing to take several actions relating to emission standards and test procedures for heavy-duty engines (HDEs) and heavy-duty vehicles (HDVs) intended for highway operation.\1\ The proposed provisions would become effective starting with the 2004 model year (MY). These actions supplement a June 1996 proposed rule (61 FR 33421, June 27, 1996), in which we proposed new emission standards for heavy-duty diesel engines (HDDE) and heavy-duty Otto-cycle engines and vehicles, and a subsequent October 1997 final rule (62 FR 54694, October 21, 1997), in which we finalized new emission standards for heavy-duty diesel engines.\2\ --------------------------------------------------------------------------- \1\ Light-duty vehicles and light-duty trucks are defined as vehicles with a gross vehicle weight rating (GVWR) below 8,500 pounds. Heavy-duty vehicles are vehicles with a GVWR greater than or equal to 8,500 pounds. Heavy-duty engines are engines used in heavy- duty vehicles. \2\ The terms ``diesel'' and ``Otto-cycle'' generally refer to the type of combustion cycle employed by an engine. In a diesel- cycle engine combustion is brought about by the compression of the fuel mixture (compression ignition), whereas in an Otto-cycle engine combustion is achieved by providing a spark to the fuel mixture (spark ignition). Although a generalization for which there are exceptions, diesel-cycle vehicles are generally fueled with diesel fuel and Otto-cycle vehicles are generally fueled with standard gasoline. --------------------------------------------------------------------------- Currently, EPA has a chassis-based regulatory program for light- duty vehicles (LDVs) and light-duty trucks (LDTs), meaning that the vehicle itself is subject to emission standards and testing. For all heavy-duty vehicles the engine alone is tested and must currently meet engine-based standards.\3\ Engine testing currently applies to all diesel-cycle and Otto-cycle heavy-duty vehicles. One of the key elements of today's action is a proposal to begin regulating a subset of heavy-duty vehicles using chassis-based requirements. The heavy-duty vehicles that are proposed to be subject to chassis-based requirements are complete Otto-cycle heavy-duty vehicles with a gross vehicle weight rating (GVWR) below 14,000 pounds.4,5 In addition, some complete gasoline and diesel-fueled heavy-duty vehicles between 8,500 and 10,000 pounds GVWR are proposed to be incorporated into the Tier 2 program proposed by EPA earlier this year (64 FR 26004, May 13, 1999). Today's proposal can generally be separated into those elements relating to the new chassis-based requirements and those elements that affect the engine-based requirements. The proposals listed below are explained in greater detail in the remainder of this document. --------------------------------------------------------------------------- \3\ Engine-based standards are expressed in terms of emissions per unit of work, whereas chassis-based (or vehicle-based) standards are expressed in terms of amount of emissions per mile driven by the vehicle. \4\ ``Complete'' vehicles are those that are manufactured with their primary cargo carrying container or device attached, whereas ``incomplete'' vehicles are those that are manufactured without the primary cargo carrying container or device attached. Incomplete vehicles (basically the engine plus a chassis) are then manufactured into a variety of vehicles, such as recreational vehicles, panel trucks, dump trucks, fire trucks, and tow trucks. \5\ Gross Vehicle Weight Rating (GVWR) is defined by federal regulation in 40 CFR 86.082-2 as ``The value specified by the manufacturer as the maximum design loaded weight of a single vehicle.'' In other words, it is the weight of the vehicle completely loaded with the maximum load that the manufacturer states the vehicle is capable of carrying. --------------------------------------------------------------------------- Some of these proposals would harmonize EPA's regulatory programs with California's current medium-duty vehicle (MDV) program (e.g., vehicle-based standards for complete Otto-cycle heavy-duty vehicles below 14,000 pounds GVWR), while others may differ from California's current requirements. These similarities and differences are outlined in the detailed discussion that follows. We request comments on the proposals described below, and encourage commenters to supply relevant data that would help us further assess the proposals.6 --------------------------------------------------------------------------- \6\ The current federal standards for Clean Fuel Vehicles are less stringent than the proposed Otto-cycle standards and the existing diesel standards for the 2004 and later model years. See 40 CFR 88.105-94. The 2004 and later model year standards proposed today would supercede the current Clean Fuel Vehicle standards, and, if EPA adopts the Otto-cycle standards proposed today and maintains the diesel standards for the 2004 and later model years, the Agency intends to undertake a rulemaking to revise the Clean Fuel Vehicle standards accordingly. --------------------------------------------------------------------------- A. Changes to the Engine-Based Program The first sections of this proposal describe the proposed revisions to the engine-based program. Some of these proposals would apply to both diesel and Otto-cycle engines, and others would apply uniquely to either diesel or Otto-cycle engines. Proposed requirements that affect the engine-based program include: Reaffirmation of the existing 2004 and later model year NMHC+NOx standard for heavy-duty diesel engines. New more stringent emission standards for 2004 and later model year Otto-cycle heavy-duty engines. A revised averaging, banking, and trading (ABT) program for Otto-cycle heavy-duty engines. Revised deterioration factor (DF) requirements for heavy- duty engines. New emission standards for heavy-duty diesel engines to improve the assurance that vehicles are emitting low levels of pollutants over a wide range of operation experienced in actual use. New supplemental test procedures for heavy-duty diesel engines associated with the proposed new emission standards.7 --------------------------------------------------------------------------- \7\ We believe that our compliance program is fundamentally incomplete until a similar form of additional assurance that Otto- cycle engines will meet applicable emission standards in-use can be added to the compliance requirements, but such provisions are not specifically proposed today. Section V of today's proposal describes several important compliance program elements that are not included in today's proposal, but that we intend to finalize such that they can take effect in conjunction with those elements in today's proposal. See section V for more information. --------------------------------------------------------------------------- B. Expanding the Otto-Cycle Vehicle-Based Program to Certain Heavy-Duty Vehicles Additional sections of this proposal describe the proposed chassis- based (or vehicle-based) program for certain heavy-duty vehicles. Many of these proposals result in harmonization with the California Air Resources Board (CARB) Medium-duty Vehicle (MDV) [[Page 58475]] Program. For the vehicle-based program, we are proposing the following elements: New standards for 2004 and later model year complete Otto- cycle heavy-duty vehicles with a GVWR below 14,000 pounds. The incorporation of certain complete Otto-cycle and diesel vehicles between 8,500 and 10,000 pounds GVWR into the Tier 2 light-duty program. These provisions would be limited to those vehicles designed primarily for personal transportation. Vehicle-based testing of all complete heavy-duty Otto- cycle vehicles below 14,000 pounds GVWR for these new standards. An averaging, banking, and trading program. On-board refueling vapor recovery (ORVR) requirements. CAP 2000 provisions.8 --------------------------------------------------------------------------- \8\ The new compliance assurance program for light-duty vehicles and light-duty trucks, known as CAP 2000 (since manufacturers may opt-in for model year 2000), streamlines the existing vehicle certification program, enabling manufacturers to save significant time and money. In addition, it requires manufacturers to test customer-owned in-use vehicles for model year 2001 and beyond. The CAP 2000 program was proposed on July 23, 1998 (63 FR 36954), and finalized on May 4, 1999 (64 FR 23906). --------------------------------------------------------------------------- Revised useful life requirements. C. Additional Changes Affecting Heavy-Duty Vehicle and Heavy-Duty Engine Programs Additional sections describe provisions or issues that apply to both heavy-duty vehicle and engine programs. These proposals include: On-board Diagnostics (OBD) requirements for heavy-duty diesel and Otto-cycle vehicles and engines up to 14,000 pounds GVWR. Non-Conformance Penalties (NCPs). D. Heavy-Duty Lead Time Issues and Voluntary Federal Standards One of the important concepts contained in the rulemaking record, is the need for harmonized, 50-state emission standards for the heavy- duty industry. Consistent national standards provide the states with the emission reductions they need, while providing manufacturers with the knowledge they can design and market one engine design regardless of what state the engine is sold to. Our proposal today would implement nationwide standards which would harmonize with California for the majority HD engines and vehicle in 2004 ( the exception being incomplete HD Otto-cycle engines.) Since the finalization of the 1997 rule for 2004 HD diesels, state and local air quality agencies have been counting on the emission reductions from the 2004 standards in order to meet their long-term air quality needs. In addition, as discussed previously in this proposal, the 2004 standards for HD Otto-cycle engines and vehicles will also provide state and local air quality agencies additional needed emission reductions. However, Section 202 of the Clean Air Act requires EPA to provide manufacturers of heavy-duty engines and vehicles four years of lead time between standards. This would require EPA to issue a final rule by the end of 1999 in order to implement new standards in 2004. We are concerned due to the short amount of time between today's proposal and the end of the calendar year that the final rule for today's proposal may not be final until after December 31, 1999, which may prevent a model year 2004 implementation of the standards proposed today. This concern does not apply for the 2004 model year heavy-duty diesel engine standards which were promulgated in 1997 and meet the lead time requirements. This four year lead time issue for the 2004 standards contained in today's proposal reflects a statutory requirement, not a technological feasibility issue. As demonstrated elsewhere in this proposal, technology is clearly available which will allow manufacturers to meet the proposed HD diesel and HD gasoline standards by 2004. The lack of more stringent federal 49-state HD standards in 2004 may lead some states with incentive to exercise their rights under Section 177 of the Clean Air Act to adopt the California HD diesel and Otto-cycle standards in order to realize the emission reductions associated with covering vehicles produced in 2004. This could result in a patchwork of emission standards across the country and could present the manufacturers with significant difficulties. In the event the Agency is unable to finalize the new standards contained in today's proposal by the end of calendar year 1999, we request comment on the appropriateness of EPA's efforts to manage the implementation of these standards and in particular, of establishing a program for those manufacturers willing to cooperate in meeting the requirements in today's proposal. We would expect that manufacturers participating in this program would merely certify their 2004 model year engines to meet all of the emission standards and requirements included in today's proposal. If the proposed standards are not finalized by the end of 1999, mandatory federal standards would apply in model year 2005, with the goal of putting in place all requirements contained in today's proposal. We request comment on whether manufacturers would need to opt-in to such a program, and how such opt- in would take place. In addition, EPA requests comment on incentives to encourage manufacturers to opt into the voluntary program. II. What Is the Environmental Need for This Proposal? This section presents information on the negative health and environmental impacts from air pollution from heavy-duty (HD) engines and vehicles, as well as EPA's assessment of the need for additional emission reductions from HD engines and vehicles in order to meet the air quality needs of the U.S. A detailed analysis and explanation of the health impacts and air quality needs was presented in the advanced notice of proposed rulemaking, as well as the preamble and the Regulatory Impact Analysis (RIA) for the proposal and final rule of the 1997 rulemaking for the 2004 standards.9 The reader should refer to those documents for additional information on this topic. --------------------------------------------------------------------------- \9\ See ``Control of Air Pollution for Heavy-Duty Engines, Advanced Notice of Proposed Rulemaking'', Available in EPA Air Docket A-95-27, Docket Item # AMS-FRL, and ``Draft Regulatory Impact Analysis: Control of Emissions of Air Pollution from Highway Heavy- Duty Engines'', available in EPA Air Docket A-95-27, Docket Item # III-B-01, and ``Control of Emissions of Air Pollution from Highway Heavy-Duty Engines; Notice of Proposed Rulemaking'' available in EPA Air Docket A-95-27, Docket Item # III-A-01, and ``Final Regulatory Impact Analysis: Control of Emissions of Air Pollution from Highway Heavy-Duty Engines'', available in EPA Air Docket A-95-27, Docket Item # V-B-01, and ``Control of Emissions of Air Pollution from Highway Heavy-Duty Engines; Final Rule,'' available in EPA Air Docket A-95-27, Docket Item # V-A-01. --------------------------------------------------------------------------- A. Need for Additional NOx and NMHC Reductions 1. Health and Welfare Effects From NMHC and NOx Oxides of Nitrogen (NOx) and volatile organic compounds (VOC) are precursors in the photochemical reaction which forms tropospheric ozone. VOC emissions from mobile sources consist mostly of nonmethane hydrocarbons (NMHC). There is a large body of evidence showing that ozone can cause harmful respiratory effects including chest pain, coughing, and shortness of breath, affecting people with compromised respiratory systems and children most severely. In addition, NOx itself can directly harm human health. Beyond their human health effects, other negative environmental effects are also associated with ozone [[Page 58476]] and NOx. Ozone has been shown to injure plants and materials; NOx contributes to the secondary formation of particulate matter (PM) (nitrates), acid deposition, and the overgrowth of algae in coastal estuaries. These environmental effects, as well as the health effects noted above, are described in the Regulatory Impact Analysis, and additional information may be found in EPA's ``staff papers'' and ``air quality criteria'' documents for ozone and nitrogen oxides.10, 11, 12, 13 --------------------------------------------------------------------------- \10\ U.S. EPA, 1996, Review of National Ambient Air Quality Standards for Ozone, Assessment of Scientific and Technical Information, OAQPS Staff Paper, EPA-452/R-96-007. \11\ U.S.EPA, 1996, Air Quality Criteria for Ozone and Related Photochemical Oxidants, EPA/600/P-93/004aF. \12\ U.S. EPA, 1995, Review of National Ambient Air Quality Standards for Nitrogen Dioxide, Assessment of Scientific and Technical Information, OAQPS Staff Paper, EPA-452/R-95-005. \13\ U.S.EPA, 1993, Air Quality Criteria for Oxides of Nitrogen, EPA/600/8-91/049aF. --------------------------------------------------------------------------- 2. Current Compliance With the Ozone NAAQS Today, many states are finding it difficult to show how they can meet or maintain compliance with the current National Ambient Air Quality Standard (NAAQS) for ozone by the deadlines established in the Clean Air Act (CAA, or ``the Act'').14 As of August, 1998, 72 million people outside of California lived in 36 metropolitan areas and two counties designated nonattainment under the 1-hour ozone NAAQS. --------------------------------------------------------------------------- \14\ See 42 U.S.C. 7401 et seq. --------------------------------------------------------------------------- In July 1997, EPA established a new 8-hour ozone NAAQS to better protect against longer exposure periods at lower concentrations than the current 1-hour standard. Under the July 1997 rule, the 1-hour NAAQS would still be applicable in certain areas during the transition to the 8-hour standard (62 FR 38856; July 17, 1997). EPA reviewed ambient ozone monitoring data for the period 1993 through 1995 to determine which counties violated either the 1-hour or 8-hour NAAQS for ozone during this time period.15, 16 Eighty-four counties violated the 1-hour NAAQS during this 3-year period, while 248 counties violated the 8-hour NAAQS. The 84 counties had a 1990 population of 47 million, while the 248 counties had a 1990 population of 83 million. EPA is reviewing more recent air quality data for 1996 and 1997. A preliminary assessment of 1994 through 1996 ozone monitoring data reveals only marginal changes in the number of counties experiencing a nonattainment problem with the 8-hour NAAQS, and essentially no change in the population levels impacted by nonattainment. --------------------------------------------------------------------------- \15\ This use of the term ``nonattainment'' in reference to a specific area is not meant as an official designation or future determination as to the attainment status of the area. \16\ See 63 FR 57356, October 27, 1998, ``Finding of Significant Contribution and Rulemaking for Certain States in the Ozone Transport Assessment Group Region for Purposes of Reducing Regional Transport of Ozone.'' --------------------------------------------------------------------------- On May 14, 1999, a panel of the U.S. Court of Appeals for the District of Columbia Circuit found, by a 2-1 vote, that Clean Air Act sections 108 and 109, as interpreted by EPA in establishing the 8-hour ozone NAAQS (as well as the new NAAQS for PM2.5 and PM10), effect an unconstitutional delegation of Congressional power. American Trucking Ass'ns, Inc., et al., v. Environmental Protection Agency, Nos. 97-1440, 1441 (D.C. Cir. May 14, 1999). The Court remanded the record to EPA. One judge dissented, finding that the majority's opinion ``ignores the last half-century of Supreme Court nondelegation jurisprudence.'' Id., slip op. at 31. The Court also ruled, regarding the 8-hour ozone NAAQS, that the statute permits EPA to promulgate a revised ozone NAAQS and to designate the attainment status of areas. However, the Court curtailed EPA's ability to require states to comply with the revised ozone NAAQS. Further the Court directed the Agency to determine whether tropospheric ozone has a beneficent effect, and if so, assess ozone's net adverse health effect. In general, the Court did not find fault with the scientific basis for EPA's determinations regarding adverse health effects from ozone. On June 28, 1999, EPA filed a petition for rehearing and petition for rehearing en banc seeking review of the panel's decision. The Court's decision does not address the provisions of section 202(a), and does not change EPA's belief that the standards in today's proposal are lawful and appropriate under these criteria. We believe that the information provided in this proposal and the draft Regulatory Impact Analysis, as well as the information that EPA relied on in setting the NAAQS for ozone, support a conclusion that ozone can be reasonably anticipated to endanger the public health or welfare. EPA's belief that it is appropriate to seek reductions of NOX and NMHCs from heavy duty vehicles and engines to protect public health or welfare is not changed by the decision of the court. 3. Future Compliance With the Ozone NAAQS Local, state and federal organizations charged with delivering cleaner air have mounted significant efforts in recent years to reduce air quality problems associated with ground-level ozone, and there are signs of partial success. NOX and VOCs appear to have been reduced, and average levels of ozone seem to have begun gradually decreasing. However, this progress is in jeopardy. EPA projects that reductions in ozone precursors that will result from the full implementation of current emission control programs will fall far short of what would be needed to offset the normal emission increases that accompany economic expansion. By the middle of the next decade, the Agency expects that the downward trends will have reversed, primarily due to increasing numbers of emission sources. By around 2020, EPA expects that NOX levels will have returned to current levels in the absence of significant new reductions.17 To the extent that some areas are seeing a gradual decrease in ozone levels in recent years, EPA believes that the expected increase in NOX will likely result in an increase in ozone problems in the future. --------------------------------------------------------------------------- \17\ See Chapter 2 of the draft Regulatory Impact Analysis for this proposal. --------------------------------------------------------------------------- The Agency has recently finalized a rulemaking requiring 22 States and the District of Columbia to submit State Implementation Plan (SIP) revisions to reduce specified amounts of emissions of NOX for the purpose of reducing NOX and ozone transport across State boundaries in the eastern half of the United States.18 The specified NOX reduction for each State varies. In making this decision EPA relied upon, among other items, ozone modeling studies for the eastern U.S. In the baseline scenario for these modeling runs EPA included the emission reductions expected from the 2004 HDDE standards. These modeling runs concluded that significant additional NOX reductions beyond the baseline case were necessary from 22 eastern States in order to meet the ozone NAAQS standards. The NOX emission reductions from the 2004 HDDE standards are assumed by these models to be part of the reductions that will be needed to meet the ozone NAAQS in these areas. The Agency did not analyze the specified reductions that would be required by the rule if the baseline did not include the 2004 HDDE standards. --------------------------------------------------------------------------- \18\ See 63 FR 57356, October 27, 1998, ``Finding of Significant Contribution and Rulemaking for Certain States in the Ozone Transport Assessment Group Region for Purposes of Reducing Regional Transport of Ozone.'' --------------------------------------------------------------------------- The deadline for submission of SIPs was recently stayed by a panel of the Court of Appeals for the D.C. Circuit pending further review. EPA believes that the October 27, 1998 rule is fully consistent with the Clean Air Act and [[Page 58477]] should be upheld. However, it should be noted that if the emission reductions sought by the SIP call are not achieved, it would be more difficult to attain the NAAQS for ozone. In addition, many states (including western states) have also included the emission reductions projected from the 2004 HDDE standards in their State Implementation Plans. This demonstrates that these states are relying on these emission reductions to meet the ozone NAAQS. 4. Contribution of HD Diesel and Gasoline Engines to Total VOC and NOX Inventories HD engines and vehicles are important contributors to the national inventories of NOX emissions, and they contribute moderately to national VOC pollution. The draft RIA for this proposal describes in detail recent emission inventory modeling completed by EPA for this proposal. Table 1 summarizes EPA's current estimates for national NOX and VOC contributions from major source categories. Table 1.--2000 National NOX and VOC Emissions [thousand short tons per year] ---------------------------------------------------------------------------------------------------------------- Emission source NOX NOX % VOC VOC % ---------------------------------------------------------------------------------------------------------------- Light-Duty Vehicles......................................... 4,420 19 4,098 25 Heavy-Duty Diesel Vehicles.................................. 2,274 10 246 1 Heavy-Duty Gasoline Vehicles................................ 318 1 198 1 Nonroad Engines and Vehicles................................ 5,343 23 2,485 15 Other (Stationary Point and Area Sources)................... 10,656 47 9,567 58 --------------------------------------------------- Total Nationwide Emissions.......................... 22,831 ........... 16,594 ........... ---------------------------------------------------------------------------------------------------------------- It should be noted that Table 1 does not include estimated NOX emission impacts associated with the previously produced HD diesel engines at issue in the recent enforcement action involving the government and several HD diesel engine manufacturers. The relationship of these consent decrees to today's proposed rule is described in section III.D. The excess NOX emissions from these engines are substantial, and would significantly increase the estimated contribution from HD diesel vehicles presented in Table 1. However, as discussed in section VI.A of this preamble, we did not update our emission inventory model to include the impact on these previously produced engines for this proposal. Notwithstanding these excess emissions, Table 1 indicates that HD gasoline and diesel vehicles will represent approximately 11 percent of national NOX emissions and two percent of national VOC emissions in the year 2000. The Regulatory Impact Analysis document for this proposal contains updated emission inventory modeling for HD vehicles. The results show that without additional HD NOX control beyond the 1998 standards, national NOX emissions from HD vehicles would decline between 2000 and 2005, but this trend would stop in 2005. After 2005, NOX emissions from the HD vehicle fleet would increase as a result of future growth in the HD vehicle market without additional emission controls. A similar trend is seen for national NMHC emissions from HD vehicles; however, NMHC emissions are projected to decrease until approximately 2010, after which changes in the make-up of the fleet result in an increase in the NMHC emissions from HD vehicles (see Chapter 5 of the draft RIA). We estimate that the HD diesel and gasoline standards contained in this proposal will result in a combined reduction by the year 2020 of 1,629,000 tons of NOX per year and 54,000 tons of hydrocarbons (HC) per year. Section VI of this preamble (``What are the Environmental Benefits of this Proposal?'') as well as the draft RIA for this proposal contain more detailed information on the Agency's projected benefits from today's proposal. B. Need for Additional PM Reductions 1. Health and Welfare Effects From PM Particulate matter is the general term for the mixture of solid particles and liquid droplets found in the air. Particulate matter includes dust, dirt, soot, smoke, and liquid droplets that are directly emitted into the air from natural and manmade sources, such as windblown dust, motor vehicles, construction sites, factories, and fires. Particles are also formed in the atmosphere by condensation or the transformation of emitted gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds. Particulate matter, like ozone, has been linked to a range of serious respiratory health problems. Scientific studies suggest a likely causal role of ambient particulate matter in contributing to a series of health effects. The key health effects categories associated with particulate matter include premature mortality, aggravation of respiratory and cardiovascular disease (as indicated by increased hospital admissions and emergency room visits, school absences, work loss days, and restricted activity days), changes in lung function and increased respiratory symptoms, changes to lung tissues and structure, and altered respiratory defense mechanisms. PM also causes damage to materials and soiling. It is a major cause of substantial visibility impairment in many parts of the U.S. Motor vehicle particle emissions and the particles formed by the transformation of motor vehicle gaseous emissions (secondary particulates) tend to be in the fine particle range. Fine particles (those less than 2.5 micrometers in diameter) are a health concern because they easily reach the deepest recesses of the lungs. Scientific studies have linked fine particles (alone or in combination with other air pollutants), with a series of significant health problems, including premature death; respiratory related hospital admissions and emergency room visits; aggravated asthma; acute respiratory symptoms, including aggravated coughing and difficult or painful breathing; chronic bronchitis; and decreased lung function that can be experienced as shortness of breath. These effects are discussed further in the RIA for this proposal, as well as the RIA for the 1997 final rule for the 2004 standards, and additional information may be found in EPA's ``staff paper'' and ``air quality criteria document'' for particulate matter.19 --------------------------------------------------------------------------- \19\ U.S. EPA, 1996, Air Quality Criteria for Particulate Matter, EPA/600/P-95/001aF. --------------------------------------------------------------------------- 2. Current and Future Compliance With the PM10 NAAQS The first NAAQS for particulate matter regulated total suspended [[Page 58478]] particulate in the atmosphere. In 1987, EPA replaced that standard with one for inhalable PM (PM10--particles less than ten microns in size), because the smaller particles, due to their ability to reach the lower regions of the respiratory tract, are more likely responsible for the adverse health effects. The major source of PM10 is fugitive emissions from agricultural tilling, construction, fires, and unpaved roads. Some revisions to the PM10 standards were made in 1997. EPA has also recently added new fine particle standards for particles less than 2.5 microns in size (PM2.5). Most of the particulate due to motor vehicles falls in the fine particle category. These standards have both an annual and a daily component. The annual component is set to protect against long-term exposures, while the daily component protects against more extreme short-term events. As noted above, on May 14, 1999, a panel of the U.S. Court of Appeals for the District of Columbia Circuit found, by a 2-1 vote, that Clean Air Act sections 108 and 109, as interpreted by EPA in establishing the new NAAQS for PM2.5 and PM10, effect an unconstitutional delegation of Congressional power. American Trucking Ass'ns, Inc., et al., v. Environmental Protection Agency, Nos. 97-1440, 1441 (D.C. Cir. May 14, 1999). The Court remanded the record to EPA. The court vacated the new PM10 standard, but has not vacated the PM2.5 standard. See American Trucking Ass'ns, Inc., et al., v. Environmental Protection Agency, No. 97-1440 (D.C. Cir. June 18, 1999). Compliance with the current PM10 standard continues to be a problem. According to the 1996 EPA Air Quality and Emissions Trends report, there were 7 million people living in 15 counties across the U.S. which exceeded the PM10 NAAQS in 1996.20 --------------------------------------------------------------------------- \20\ U.S. EPA, January 1998, ``National Air Quality and Emissions Trends Report, 1996'', EPA 454/R-97-0013. --------------------------------------------------------------------------- EPA recently projected ambient PM10 levels and the number of U.S. counties expected to be in violation of the revised PM10 NAAQS in 2010.21 Based on the 1990 census, about 10 million people live in the 11 counties projected to be in nonattainment of the revised PM10 NAAQS. --------------------------------------------------------------------------- \21\ Regulatory Impact Analyses for the Particulate Matter and Ozone National Ambient Air Quality Standards and Proposed Regional Haze Rule, Innovative Strategies and Economics Group, Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, N.C., July 16, 1997. --------------------------------------------------------------------------- 3. Contribution of HD Diesel and Gasoline Vehicles to PM Inventories a. Contribution to National PM10 Inventories The national inventory of PM10 is dominated by natural sources (wind erosion) and so-called miscellaneous sources, which include paved and unpaved road dust, agricultural crops, fugitive dust, and dust from construction activities. Together natural and miscellaneous sources represented approximately 90 percent of national PM10 emissions in 1996. Since these sources are not readily amenable to regulatory standards and controls, it is appropriate to focus on more traditional ``controllable'' portions of the particulate pollution problem when considering the need for PM controls. Excluding natural and miscellaneous sources, HD vehicles (gasoline and diesel) represent approximately five percent of the remaining man-made sources of PM10 in 1996, virtually all (95 percent) of which is from diesel vehicles.22 --------------------------------------------------------------------------- \22\ U.S. EPA, December 1997, ``National Air Pollutant Emission Trends, 1900-1996'', EPA-454/R-97-011. --------------------------------------------------------------------------- In the proposal for the 1997 final rule for the 2004 standards, EPA presented data on future projections of mobile and stationary source PM10 national emission inventories out to the year 2010, as well as a break-down of mobile sources into on-highway light-duty, on- highway heavy-duty, and nonroad categories (see 61 FR 33432-33440, June 27, 1996). These projections showed that without additional future controls on PM or NOX emissions, annual PM emissions (tons/ year) for all mobile sources would begin to rise after the year 2000. The Regulatory Impact Analysis document for this proposal presents the results of updated emission modeling specifically for HD vehicles. These results show that the annual national PM10 emissions from HD vehicles (tons/year) are expected to decline between now and approximately the year 2010, after which increases in the size of the fleet will result in a steady increase into the future (see Chapter 5 of the draft RIA). b. Source-apportionment Studies for Diesel PM Discussion of PM inventories from HD vehicles, and in particular HD diesel vehicles which represent the vast majority of the HD PM emissions, can be discussed in terms other than just contributions to national yearly emission inventories. In recent years several research groups have been looking at the contribution of diesel PM in selected urban and rural areas. In several cases these studies indicate that the contribution from diesels in certain urban areas to PM emissions is much larger than is indicated by national PM inventories. Several studies have been performed in the past several years which have attempted to apportion particulate matter collected at specific sites to individual source categories, i.e., source apportionment studies. These studies collect particulate matter samples in the ambient air which are subsequently analyzed using various chemical techniques in order to estimate what sources contributed to the sample. There have been a number of source apportionment studies for mobile source particulate emissions. Among the most recent and thorough are studies by the state of Colorado (the Northern Front Range Air Quality Study [NFRAQS]) for the Denver area and the California Institute of Technology for the Los Angeles area. These studies emphasize particulate smaller than 2.5 microns. Also, EPA has a cooperative agreement with the Desert Research Institute (DRI); under this agreement, DRI is completing a detailed report on mobile source particulates; a major portion of this report summarizes source apportionment studies for particulates that include those from mobile sources.23 --------------------------------------------------------------------------- \23\ Draft report for EPA from the Desert Research Institute, June 30, 1998, Available in EPA Air Docket A-98-32, Item # --01. --------------------------------------------------------------------------- Source apportionment work involves collecting and analyzing a number of ambient particulate samples from a number of specific sources such as gasoline and diesel vehicles. Some samples of high molecular weight hydrocarbons are frequently also collected and analyzed, these hydrocarbons can be transformed to particulates in the ambient air; such compounds include polycyclic organic matter. These samples are analyzed in detail to determine what specific compounds are present including those in trace amounts that are more common from one source type than from others, these traces are called source signatures. From these analyses, a number of source signatures are developed including those for gasoline and diesel vehicles. Source apportionment work also involves collecting and analyzing a larger number of ambient particulate and, frequently, high molecular weight hydrocarbon. The compounds found in these samples can be compared to the source signatures to determine what and how much individual sources contribute to the ambient particulate. [[Page 58479]] Source apportionment work is subject to complications and uncertainty. Thus, no single study should be considered definitive. Additional information on source apportionment techniques, and the uncertainties associated with the techniques, can be found in Chapter 2 of the RIA for this proposal. The NFRAQS study analyzed ambient particulate samples in the Colorado area including Denver using data it collected on the chemical speciation from specific source types to determine how much various mobile and stationary source types contribute to PM2.5. Authorized by Colorado state legislation, the total study was funded by 37 government, industry, and trade association groups. The many outputs and conclusions from the NFRAQS will not be discussed here, only source apportionment results for diesel engines are summarized. Complete copies of the NFRAQS are available from the following World Wide Web site, http://charon.cira.colostate.edu/. The NFRAQS included several time periods and several locations in and around Denver. Two locations, Brighton and Welby, during the winter of 1997 included the most detailed sampling and analysis, which allowed the researchers to estimate very detailed source specific contributions, including the contributions to PM2.5 from diesel exhaust (all diesel, nonroad and on-highway sources were not differentiated). Based on this work, it was estimated that diesel exhaust sources contributed 10 percent of the total mass of PM2.5 in the areas of Brighton and Welby in the winter of 1997. Similar work has been done for the Los Angeles area by a group of researchers at the California Institute of Technology. This work concluded that direct emissions from diesel exhaust represented approximately 30 percent of fine PM mass on an annual basis in downtown Los Angeles in 1982.24 In follow-on work looking at the city of Claremont, California in 1987, direct diesel exhaust was found to represent approximately 13 percent of PM2.5 mass, and 9 percent of PM10 mass.25 --------------------------------------------------------------------------- \24\ ``Source Apportionment of Airborne Particulate Matter Using Organic Compounds as Tracers'', J.J. Schauer, W.F. Rogge, L.M. Hildemann, M.A. Mazurek, and G.R. Cass, Atmospheric Environment, Vol. 30, No. 22, 1996. \25\ ``Source Contributions to the Size and Composition Distribution of Urban Particulate Air Pollution'', M.J. Kleeman and G.R. Cass, Atmospheric Environment, Vol. 32, No. 16, 1998. --------------------------------------------------------------------------- The California Institute of Technology has also collected ambient particulate in the Boston, MA and Rochester, NY areas. These samples, especially those for Boston, show that carbonaceous particulate is the largest single constituent in PM2.5 for these areas. Mobile source particulate, including diesels, is an important contributor to carbonaceous particulate. The Boston and Rochester samples have not yet been used for source apportionment work. Other ambient samples collected in the eastern U.S. such as Washington, DC show carbonaceous particulate to be an important constituent of PM2.5, although sulfates is a somewhat larger constituent and nitrates a much smaller constituent. Particulate samples collected in the western U.S. such as in Spokane, WA, Phoenix, AZ and the San Joaquin Valley of California show that carbonaceous particulate is the major constituent with sulfates/nitrates being lesser constituents although nitrates are more important in southern California than elsewhere in the United States. This work is summarized in the EPA report ``National Air Pollutant Emission Trends, 1900- 1996.'' 26 --------------------------------------------------------------------------- \26\ ``National Air Pollutant Emission Trends, 1900-1996'', EPA Report 454/R-97-011, December 1997. --------------------------------------------------------------------------- The reports on source apportionment summarized in this section indicate that the contribution of diesel engines to PM inventories in several local areas around the U.S. are much higher than what would be assumed from looking only at the estimates presented in national PM emission inventories. One possible explanation for this is the concentrated use of diesel engines in certain local or regional areas which is not well represented by the national, yearly average presented in national PM emission inventories. C. Air Toxics From HD Engines and Vehicles In addition to contributing to the health and welfare problems associated with exceedances of the National Ambient Air Quality Standards for ozone and PM10, emissions from HD diesel and Otto-cycle vehicles include a number of air pollutants that increase the risk of cancer or have other negative health effects. These air pollutants include benzene, formaldehyde, acetaldehyde, 1,3-butadiene, and diesel particulate matter. For several of these pollutants, motor vehicle emissions are believed to account for a significant proportion of total nation-wide emissions. All of these compounds are products of combustion; benzene is also found in nonexhaust emissions from gasoline-fueled vehicles. These reductions in hydrocarbon emissions from HD vehicles resulting from today's proposal will further reduce the potential cancer risk and other health risks from these air toxics (other than diesel PM) because many of these pollutants are themselves VOCs. Diesel engine particulate matter is also a potential concern because of its possible carcinogenic and mutagenic effects on people. Diesel PM is made of hundreds of chemical species, including many organic and metallic compounds. Researchers have been investigating the potential health hazards associated with exposure to diesel PM for many years.27 EPA's Office of Research and Development is currently updating the EPA's diesel emission health assessment document. However, the document has only been released as a preliminary draft, and is currently undergoing review by the Clean Air Scientific Advisory Committee. A final version is not expected to be available until late 1999.28 --------------------------------------------------------------------------- \27\ ``Diesel Exhaust: A Critical Analysis of Emissions, Exposure, and Health Effects'', Health Effects Institute, April, 1995. \28\ ``Preliminary Draft--Health Assessment Document for Diesel Emissions'', U.S. EPA, February 1998, EPA 600/8-90/057C. --------------------------------------------------------------------------- The California Air Resources Board and the California Office of Environmental Health Hazard Assessment (COEHHA) have undertaken an assessment of the cancer and non-cancer effects from exposure to diesel exhaust, including the particulate matter component of diesel exhaust, to determine whether diesel exhaust should be classified as a Toxic Air Contaminant (TAC) under California law. The evaluation of diesel exhaust by CARB and COEHHA began in 1989, in June of 1998 a Staff Report was published which recommended that diesel exhaust be classified as a TAC.29 In a CARB Board hearing held in August, the Board decided to identify diesel exhaust particulate matter as a TAC.30 --------------------------------------------------------------------------- \29\ California Air Resources Board--Staff Report--``Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant'', June 1998. \30\ California Air Resources Board, Resolution 98-35, August 27, 1998. --------------------------------------------------------------------------- EPA will be addressing the issues raised by air toxics from motor vehicles and their fuels in a separate rulemaking that EPA is initiating in the near future under section 202(l)(2) of the Act. That rulemaking will address the emissions of hazardous air pollutants from motor vehicles and fuels, and the appropriate level of control of hazardous air pollutants from these sources. III. What Is the Important Background Information for This Proposal? Under EPA's classification system, heavy-duty vehicles are those with a [[Page 58480]] GVWR of 8,500 pounds or more.\31\ The State of California classifies the lighter end of this class--up to 14,000 pounds GVWR--as ``medium- duty vehicles.'' Heavy-duty engines are engines used in heavy-duty vehicles. Heavy-duty engines and vehicles are used in a wide range of applications, from large full size pick-up trucks to the largest commercial trucks. Because one type of heavy-duty engine may be used in many different applications, EPA emission standards for the heavy-duty class of vehicles have historically been based on the emissions performance of the engine (and any associated aftertreatment devices) as tested separately from the vehicle chassis. --------------------------------------------------------------------------- \31\ The Clean Air Act defines heavy-duty vehicles as those with a GVWR of 6,000 pounds. However, EPA has classified vehicles between 6,000 and 8,500 pounds GVWR as light-duty vehicles, while treating them as heavy-duty for statutory purposes. Vehicles weighing between 6,000 and 8,500 pounds GVWR are not addressed generally in this proposed rulemaking. --------------------------------------------------------------------------- Highway HDEs are categorized into diesel-cycle (compression- ignited) and Otto-cycle (spark-ignited) engines. Most diesel-cycle engines are fueled by diesel fuel, but heavy-duty diesel-cycle engines can also be fueled by methanol or natural gas. The heavy-duty diesel engine class is further subdivided by EPA into three subclassifications or ``primary intended service classes''; light, medium, and heavy HDDEs (see 40 CFR 86.090-2). HDDEs are categorized into one of the three subclasses depending on the GVWR of the vehicles for which they are intended, the usage of the vehicles, the engine horsepower rating, and other factors. The subclassifications allow EPA to more effectively set requirements that are appropriate for the wide range of sizes and uses of HDDEs. Most highway heavy-duty Otto-cycle vehicles and engines are gasoline-fueled, but may also be fueled with alternative fuels including methanol and gaseous fuels such as natural gas. Heavy-duty Otto-cycle vehicles and engines include large full size pick-up trucks, full size cargo and passenger vans, and the largest sport utility vehicles. Approximately 75 percent of heavy-duty Otto-cycle vehicles are in the 8,500-10,000 pound GVWR range, and the vast majority of these are sold as ``complete'' vehicles. The majority of heavy-duty Otto-cycle vehicles above 10,000 pounds GVWR are sold as ``incomplete'' vehicles, meaning that they are manufactured without their primary cargo carrying container or device attached. These incomplete vehicles (basically the engine plus a chassis) are then manufactured into a variety of vehicles, including recreational vehicles, panel trucks, tow trucks, and dump trucks. EPA's NOX standard for 1998 and later model year diesel and Otto-cycle heavy-duty engines is 4.0 grams per brake horsepower- hour (g/bhp-hr). The hydrocarbon standards for 1998 and later model year Otto-cycle engines are 1.1 g/bhp-hr for engines used in lighter vehicles (8500 to 14,000 pounds GVWR) and 1.9 g/bhp-hr for engines used in heavier vehicles (greater than 14,000 pounds GVWR), and the 1998 and later model year hydrocarbon standard for HDDEs is 1.3 g/bhp-hr. EPA currently requires testing of the engine (with emissions control systems in place) rather than the entire vehicle. Thus, the standards are in units of g/bhp-hr (i.e., grams of emissions per unit of work the engine performs over the test cycle), rather than the grams-per-mile unit currently used for testing passenger cars and light-duty trucks. This proposed rulemaking is the continuation of a rulemaking process for heavy-duty engines which began in 1995 with an Advanced Notice of Proposed Rulemaking (ANPRM) (60 FR 45580, August 31, 1995). As discussed below, a 1996 Notice of Proposed Rulemaking proposed the same NMHC+NOX standards for both Otto-cycle and diesel engines (61 FR 33421, June 27, 1996). However, EPA did not finalize the proposed NMHC+NOX standard for Otto-cycle engines in the final rule published in October 1997 (62 FR 54694, October 21, 1997). EPA did finalize a new NMHC+NOX emission standard for HDDEs, starting with the 2004 model year, but committed to review the appropriateness of this standard in 1999. This NPRM thus addresses two broad issues that remain from earlier rulemaking efforts--a review of the NMHC+NOX standard for diesel engines and a supplemental proposal addressing new NMHC+NOX standards for heavy-duty Otto-cycle engines and vehicles. The previous rulemaking documents, and the documents referenced therein (see EPA Air Docket No. A-95-27), contain extensive background on the engines and vehicles, the affected industry, and the need for lower emissions standards. A. Statement of Principles and Rulemaking History In July of 1995, EPA, the California Air Resources Board, and heavy-duty engine manufacturers representing over 90 percent of annual nationwide engine sales signed a Statement of Principles (SOP) that established a framework for a proposed rulemaking to address concerns regarding the growing contribution of heavy-duty engines to air pollution problems. The SOP contained levels for a new proposed standard for NMHC+NOX that would become effective in model year 2004. The SOP also contained several key provisions in addition to the standards. The SOP discusses the need to review in 1999 the technological feasibility of the NMHC+NOX standard and its appropriateness under the Clean Air Act. Also, the SOP outlines a plan for developing technology with the goal of reducing NOX emissions to 1.0 g/bhp-hr and particulate matter to 0.05 g/bhp-hr while maintaining performance, reliability, and efficiency of the engines. EPA sought early comment on the general regulatory framework laid out in the SOP in an ANPRM on August 31, 1995 (60 FR 45580), then subsequently issued an NPRM on June 27, 1996 (61 FR 33421). On October 21, 1997, EPA issued a final rule (62 FR 54694). The centerpiece of the final rule was the new NOX + NMHC standard of 2.4 g/bhp-hr (or 2.5 g/bhp-hr with a 0.5 g/bhp-hr NMHC cap) for 2004 and later model year heavy-duty diesel-cycle engines. The rule also adopted other related compliance provisions for diesel-cycle heavy-duty engines beginning with the 2004 model year, as well as revisions to the useful life for the heavy heavy-duty diesel engine service class. As explained in the following section, no new standards were finalized for on-highway heavy-duty Otto-cycle engines. The final rule also contained modified ABT provisions for heavy- duty diesel engines, allowing EPA to finalize a more stringent engine standard than might otherwise be appropriate under the CAA, since ABT reduces the cost and improves the technological feasibility of achieving the NMHC+NOX standard. The changes to the ABT program provide the manufacturers with additional product planning flexibility and the opportunity for a more cost-effective introduction of product lines meeting the new standard. We also believe that the ABT program can create an incentive for the early introduction of new emission control technology. EPA did not finalize new ABT provisions for Otto-cycle engines because EPA did not take action at that time on new standards for those engines. In summary, engine manufacturers will be able to generate credits under the new program beginning with the 1998 model year for use only in 2004 and later model years. The credits in the modified program will have unlimited life, as opposed to the three year credit life contained in the current HD program. Also, engines [[Page 58481]] with certification levels at or below a certain cut point are able to generate undiscounted credits. Credits generated by engine families certified above the specified cut point are discounted by 10 percent for purposes of banking and trading. The pre-existing ABT program was retained for engine families using credits before 2004, and for Otto- cycle engines which cannot earn credits in the modified program, as noted above. In 2004, the certification level cut-point is adjusted to reflect the implementation of the new standard. EPA also finalized several provisions to help ensure in-use durability. First, EPA increased the useful life period for heavy heavy-duty diesel engines to 435,000 miles. This new useful life represents a 50 percent increase and is more representative of the durability of current and future heavy heavy-duty diesel engines. In addition, longer allowable maintenance intervals were finalized for some critical emission-control components, including exhaust gas recirculation (EGR) systems, catalysts, and other add-on emissions control components. Generally, the maintenance intervals for the components are set at 100,000 miles for light heavy-duty diesel engines and 150,000 miles for medium and heavy heavy-duty diesel engines. Warranty regulations were also revised to better reflect current industry practices. Other provisions of the October, 1997 final rule address the period after the manufacturer's responsibility for emission control ends, including engine rebuilding. One of those provisions requires engine manufacturers to establish a section in the owner's manual for add-on components that includes recommendations for maintenance and diagnosing malfunction. In addition, all on-board monitoring used to satisfy the engine's allowable maintenance must not be designed to turn off after the end of the useful life. Finally, EPA established provisions to address engine rebuilding which specify what actions are needed to ensure proper operation of emissions control components and ensure that rebuilding does not result in loss of emissions control. Removal or disabling of emissions related components, resulting in a higher emitting vehicle, are considered tampering. B. 1999 Review of Heavy-Duty Diesel Engine NMHC+NOX Standards In addition to the elements of the final rule described above, EPA finalized a regulatory provision providing for a 1999 review of the new NMHC+NOX emission standard for HDDEs. EPA committed to ``reassess the appropriateness of the standards under the Clean Air Act, including the need for and technical and economic feasibility of the standards based on information available in 1999'' (See 62 FR 54699, October 21, 1997). This provision was put in place because the technologies required to meet the 2004 NMHC+NOX standard for HDDEs were, at the time the standard was finalized, not yet fully developed and proven. This commitment was spelled out in regulatory language in the final rule in 40 CFR 86.004-11, paragraph (a)(1)(i)(E), which reads: No later than December 31, 1999, the Administrator shall review the emissions standards set forth in paragraph (a)(1)(i) of this section and determine whether these standards continue to be appropriate under the Act. In the preamble to the 1997 final rule EPA outlined the three potential outcomes of the 1999 review: further tightening of the NMHC+NOX standard, no change to the standard, or a relaxation of the standard. The preamble noted that if EPA determined through the 1999 review process that a tighter standard was feasible and appropriate under the Clean Air Act, such tighter standard would be proposed. Conversely, if EPA's 1999 review process concluded that the 2004 NMHC+NOX standard was not technologically feasible, the 1997 preamble outlined alternative less stringent sets of standards that EPA would propose. These alternative less stringent standards would depend on EPA's conclusions regarding the necessity for diesel fuel changes and, if changes were found to be needed, whether or not EPA took action to require such changes. Specifically, the preamble stated that if EPA finds through the 1999 review process that the existing 2004 NMHC+NOX standard is not feasible, a standard no higher than 2.9 g/bhp-hr NMHC+NOX (or 3.0 g/bhp-hr NMHC+NOX with a limit of 0.6 g/bhp-hr NMHC) would be proposed. If EPA were to find that changes to diesel fuel would be necessary to meet the 2004 NMHC+NOX standards, and if EPA did not engage in a rulemaking to make such changes, then standards no higher than 3.4 g/bhp-hr NMHC+NOX (or 3.5 g/bhp-hr NMHC+NOX with a limit of 0.6 g/bhp-hr NMHC) would be proposed. While the specific regulatory provision is limited to the NMHC+NOX standard for review in 1999, in the preamble to the final rule EPA committed to investigating or seeking comment on several other issues in the context of the 1999 review. These additional issues include: An evaluation of whether the appropriateness and technical feasibility of the 2004 standards depend upon changes to diesel fuel. A reassessment of the appropriateness of the 2004 NMHC+NOX standard in the context of the current PM standard. Non-conformance penalty provisions for the 2004 HDDE standards. C. Proposal for Heavy-Duty Gasoline Engine Standards 1. Summary of Comments on 1996 NPRM As was noted above, EPA proposed the same NMHC+NOX standard for diesel and Otto-cycle heavy-duty engines in the 1996 NPRM. In the comment period following the NPRM, several commenters urged the Agency to reconsider its proposal for Otto-cycle engines. The commenters argued that the proposal ignored the true low emissions capability of gasoline-powered vehicles equipped with advanced three way catalysts. Environmental groups provided comments highlighting manufacturers' certification data for the 1996 model year, which included some engine families with emission levels considerably below the standards proposed for the 2004 model year. One commenter recommended that the proposed standard be phased in earlier than 2004 for Otto-cycle engines since the emissions control technology capable of meeting the NMHC+NOX standard was more advanced for Otto- cycle engines than for diesel engines. Manufacturers commented that the proposed standard was appropriate for Otto-cycle engines and that EPA should not use certification data as a basis for determining the feasibility of a lower standard. Manufacturers noted that due to the potential for in-use deterioration of catalysts and oxygen sensors, they must design to emissions targets and certification levels well below the standards. Catalysts experience wide variations in exhaust temperature due to the wide and varied usage of vehicles in the field. Some vehicles may experience more severe in- use operation than is represented by the durability testing conducted for engine certification. Manufacturers argued that this variation in in-use operation has an impact on emission system durability not represented by engine certification data and deterioration factors. They argued that it is necessary to certify engines to levels well below the standards to ensure in-use compliance of all engines. One manufacturer presented light-duty [[Page 58482]] vehicle and light-duty truck data to demonstrate that certification levels were about half the standard while some vehicles' in-use emissions levels were higher although not above the standard.\32\ --------------------------------------------------------------------------- \32\ Comments from Kelly Brown, Ford Motor Company, to Margo Oge, Director OMS, U.S. EPA, September 9, 1996, Docket A-95-27, IV- D-26. --------------------------------------------------------------------------- 2. Analysis Leading to Decision To Not Finalize Otto-Cycle Standards EPA, in deciding whether to finalize the NMHC+NOX standard as originally proposed, had to determine if the proposed standards met the requirements of section 202(a)(3)(A) of the Clean Air Act.\33\ For Otto-cycle engines, EPA examined 1997 model year certification data and found some engines certified to very low emissions levels. The certification data for 1997 showed a large number of engine families emitting at or below the 2004 levels as they were proposed, with some engines certified at emission levels only ten to twenty percent of the proposed 2004 emission standards. Examples of these engines are listed in Table 2.\34\ --------------------------------------------------------------------------- \33\ Section 202(a)(3)(A) of the Clean Air Act specifies that regulations ``shall contain standards which reflect the greatest degree of emission reduction achievable through the application of technology which the Administrator determines will be available for the model year to which such standards apply, giving appropriate consideration to cost, energy, and safety factors associated with the application of such technology.'' \34\ Note that the text here is a brief assessment of the information EPA had available at the time a decision was made to refrain from finalizing heavy-duty Otto-cycle standards. However, today's proposal, and the accompanying analysis of feasibility in the RIA, uses more recent data. Table 2.--1997 MY Heavy-Duty Otto-Cycle Engine Certification Data ---------------------------------------------------------------------------------------------------------------- NOX HC certification Engine size (liter) certification level (g/bhp- NOX + HC (g/bhp- level (g/bhp-hr) hr) hr) ---------------------------------------------------------------------------------------------------------------- 4.3....................................................... 1.2 0.3 1.5 5.4....................................................... 0.2 0.1 0.4 5.7....................................................... 1.4 0.1 1.5 6.8....................................................... 0.1 0.1 0.2 7.4....................................................... 1.2 0.4 1.6 8.0....................................................... 2.2 0.1 2.3 Emission Standards........................................ 5.0 *1.3 N/A ---------------------------------------------------------------------------------------------------------------- *(1.9 above 14,000 pounds GVWR) EPA also examined certification data for California vehicles. California's MDV program requires all complete heavy-duty vehicles (i.e., all vehicles that exit the manufacturer's assembly line with their cargo carrying device or container attached) up to 14,000 pounds GVWR to be certified on the chassis-based (vehicle) federal test procedure (EPA currently requires engine-based testing of vehicles in this class). Table 3 lists examples of model year 1997 California vehicle certification results for vehicles above 8,500 pounds GVWR.\35\ These vehicles were required to meet the California Tier 1 standards which are listed on the table. Starting with the 1998 MY, California is requiring manufacturers to begin phase-in of vehicles meeting more stringent Low Emission Vehicle (LEV) standards which are also listed in Table 3 for these vehicles. --------------------------------------------------------------------------- \35\ All of the vehicles and standards listed are categorized MDV3 in the medium duty vehicle program which includes vehicles with test weights between 5,751-8,500. Test weight is the average of the curb weight and gross vehicle weight. Table 3.--1997 MY California Medium-Duty Vehicle Certification Data [120,000 mile] ---------------------------------------------------------------------------------------------------------------- NOX level (g/ HC level (g/ NOX+HC (g/ Engine size (liter) mile) mile) mile) ---------------------------------------------------------------------------------------------------------------- 5.4............................................................. 0.20 0.220 0.42 5.7............................................................. 0.88 0.160 1.04 6.8............................................................. 0.42 0.300 0.72 7.4............................................................. 0.48 0.210 0.69 7.5............................................................. 0.24 0.190 0.43 8.0............................................................. 0.51 0.234 0.74 Tier 1 standards................................................ 1.53 0.560 N/A LEV standards................................................... 0.90 0.280 N/A ---------------------------------------------------------------------------------------------------------------- EPA understands that manufacturers have established certification levels which represent typical vehicle usage and that manufacturers have given themselves a significant margin between the certification levels and the standards to account for variability including more severe usage and deterioration. However, EPA found that some 1997 model year engines were certified to very low levels even taking the need for a compliance margin into consideration. At the time, however, EPA did not believe it was appropriate, given the lack of a full opportunity for notice and comment, and the need for more thorough data and analyses, to proceed directly to finalizing standards tighter than those originally proposed for heavy-duty Otto-cycle engines. For these reasons, EPA did not finalize the proposed standards for Otto-cycle engines and asserted that more stringent standards might be reasonably achievable in the 2004 model year time frame. With the lead time available for the 2004 time frame and in the context of EPA's emission control program at the time, EPA concluded in 1997 that final action establishing an appropriate standard for Otto-cycle heavy-duty engines should be the subject of a future action that more thoroughly assessed [[Page 58483]] whether a more stringent standard might be achievable and appropriate for some or all categories of Otto-cycle heavy-duty engines. D. Consent Decrees With Heavy-Duty Diesel Engine Manufacturers The Department of Justice and EPA recently filed proposed consent decrees with seven of the largest heavy-duty diesel engine manufacturers in the U.S. in order to resolve the problems uncovered from current and past heavy-duty diesel engines which the government does not believe meet existing standards and defeat device rules. (See 63 FR 59330-59334; November 3, 1998). In these consent decrees with the Federal Government these manufacturers have agreed, among other things, to meet a 2.5g/bhp-hr limit on NMHC+NOX no later than October 1, 2002. The majority of these engine manufacturers have also agreed to produce engines by October 1, 2002 which meet a 1.25 not-to- exceed limit, a 1.0 Euro III limit (on which the Agency's proposed supplemental steady-state cycle is based), and to test engines over and eventually comply with a load response test and limit. \36\ The fact that these engine manufacturers have agreed to meet the 2004 standards in 2002 gives the Agency additional confidence that the NMHC+NOX standard being reaffirmed in today's proposal is appropriate for the 2004 model year. Other elements of these consent decrees that are carried over to today's proposed rule include the addition of a new steady state certification test and a new ``not-to- exceed'' (NTE) approach to in-use testing. In addition, under the consent decrees the manufacturers are required to invest considerable resources to evaluate instrumentation and methodologies for on-road testing, providing an additional basis for EPA's expectations regarding the advancement of technology in this area. --------------------------------------------------------------------------- \36\ The Consent Decrees establish target limits for a load response test of 1.3 times the federal test procedure (FTP) standard for NMHC+NOX and 1.7 times the FTP standard for PM. These limits would take effect for affected manufacturers after October 1, 2002. However, the Consent Decrees establish a process to determine whether these limits should be modified to ensure that they are the lowest achievable given the technology available at the time. Under this process, manufacturers would submit load response test data with their certification applications starting with the 1999 model year, and by October 1, 2000, the parties to the Consent Decrees would review these data to determine appropriate emission limits. --------------------------------------------------------------------------- The Agency believes these consent decrees will partially address the emission problems from these previously produced engines. However, we do not believe that relying on the current compliance program and the use of enforcement actions in the future is the most appropriate method to assure in-use compliance of heavy-duty engines under all operating conditions. We estimate that the more than 1,000,000 engines at issue in these consent decrees produced since 1988 will have resulted in excess NOX emissions of more than 15 million tons over the lifetime of the engines, with an estimated 1.3 million excess tons of NOX being emitted in 1998 alone. This level of NOX emissions is enormous. To put this in perspective, the Agency's National Air Pollutant Emission Trends report for 1900- 1996 estimates the total U.S. emission inventory for annual NOX emissions was 23.3 million tons. These estimates do not include the previously unknown excess NOX emissions from on- highway heavy-duty diesels. Assuming the total 1998 national NOX emissions are similar to 1996, the 1.3 million tons excess NOX emissions from heavy-duty diesels in 1998 represent approximately five percent of the national total. We believe the new compliance requirements proposed in this NPRM must be put in place in order to assure that the public's health and welfare are protected from these types of excess emissions in the future. IV. What Are the Details of This Proposal? A. Reaffirmation of 2004 NMHC + NOX Standard for Heavy-Duty Diesel Engines In today's proposal, the Agency is reaffirming the technological feasibility, cost-effectiveness, and appropriateness under the Clean Air Act of the 2004 NMHC+NOX standard for HDDEs, including the appropriateness of the current 0.1g/bhp-hr PM standard. In 1997, the Agency finalized on-highway heavy-duty diesel standards for model year 2004 of: 2.4 g/bhp-hr NMHC + NOX or 2.5 g/bhp NMHC + NOX with a limit of 0.5 g/bhp-hr on NMHC For today's proposal, the Agency has conducted a thorough analysis of information and data which has become available since the finalization of these standards in October of 1997. As discussed elsewhere in this preamble and in the RIA for this proposal, manufacturers have made significant progress toward meeting the 2004 standards, and in fact, the Agency believes a large number of manufacturers will be meeting the 2004 model year standards by the end of 2002. Manufacturers have made significant progress in several key technologies for HD diesels which will allow them to meet the 2004 NMHC+NOX standards. These areas included advanced fuel injection systems, EGR, advanced turbocharger systems, and advanced electronic controls. In the relatively short time frame since the finalization of the 1997 rule, manufacturers have either announced or begun to introduce second generation electronically controlled fuel injection systems, such as the Cummins Accumulator Pump system (CAPS), and the Navistar/Caterpillar second generation hydraulicly actuated electronic unit injections (HEUI) and mechanically actuated electronic unit injection (MEUI) systems.\37\ \38\ \39\ \40\ \41\ These newer systems provide manufacturers with enormous capabilities to tailor-fit engine injection pressures, injection rate shaping, and pilot injection (or multiple pilot injections) to lower NOX emissions while still complying with the current PM standard, and maintaining or improving upon the fuel efficiency, performance, and durability expected by HDDE users. These advanced fuel systems will be coupled with new, sophisticated EGR systems. As discussed in the RIA, considerable research has been done in the last few years on the application of EGR to heavy-duty diesels in order to meet the 2004 standards. Based on this relatively recent information, it now appears manufacturers will use a combination of hot and cooled EGR, sometimes at relatively high EGR flow rates, on the order of 40-50 percent under certain operating conditions, to achieve the 2004 NMHC+NOX standards. The Agency believes EGR is perhaps the single most significant advance in emission control technology for HD diesels which will enable the approximately 50 percent reduction in NOX emissions required by the 2004 standards. As discussed in the draft RIA, cooled EGR is very effective at reducing NOX emissions. Laboratory studies have shown that EGR can reduce NOX emissions by up to 90 percent at [[Page 58484]] light load and up to 60 percent at full load near rated speed.42 Other studies have shown similar reductions at other speeds and loads.43 In addition to fuel system changes and EGR, turbocharger manufacturers and engine manufacturers are in the process of developing new variable nozzle turbochargers (VNT, sometimes referred to as variable geometry turbochargers), as well as more advanced, electronically controlled wastegated turbochargers, for both performance and emission reasons. The new VNT systems will allow manufacturers more flexibility in how they design their EGR systems, and provide improved performance for engine users. Finally, engine manufacturers continue to develop and introduce highly sophisticated electronic control management systems based on the latest microprocessor technology available.\44\ These next generation control systems integrate the complete engine/powertrain system, including the injection system, EGR, and turbocharger, which allows the manufacturer to maximize the engine performance as well as emission control system. The RIA for this proposal provides additional detail on these technologies, as well as the Agency's cost analysis for the combination of technologies which EPA expects will be used to meet the 2004 NMHC+NOX standards. Based on the most recent information available, the Agency is confident that engine manufacturers are making sufficient progress in the development of technologies which will allow them to meet the 2004 NMHC+NOX standards. As discussed below, the Agency does not believe changes in diesel fuel quality are needed for engines to meet these standards. --------------------------------------------------------------------------- \37\ SAE paper 973182, ``Advanced Technology Fuel System for Heavy-duty Diesel Engines''. \38\ Diesel Progress, August 1998, ``CAT Gears Up Next Generation Fuel Systems'', available in EPA Air Docket A-98-32, Docket Item #II-D-03. \39\ Diesel Progress, August 1998, ``Next Generation MEUI-B to Debut in 2001'', available in EPA Air Docket A-98-32, Docket Item #II-D-03. \40\ Diesel Progress, October 1998, ``No Mistaking New Cummins ISL Engine'', available in EPA Air Docket A-98-32, Docket Item #II- D-04. \41\ ``Cummins New Midrange Fuel System'', presented by John Youngblood, Cummins Engine Company, at the SAE Diesel Technology TOPTEC, April 22, 1998, available in EPA Air Docket A-98-32, Docket Item #II-D-01. \42\ Dickey D.W., T.W. Ryan III, A.C. Matheaus: ``NOX Control in Heavy-Duty Engines-What is the Limit?'', SAE paper 980174, 1998. Dickey; and, Zelenka P., H. Aufinger, W. Reczek, W. Cartellieri: ``Cooled EGR-A Key Technology for Future Efficient HD Diesels,'' SAE paper 980190, 1998. \43\ Kohketsu S., K. Mori, K. Sakai, T. Hakozaki: EGR Technologies for a Turbocharged and Intercooled Heavy-Duty Diesel Engine,'' SAE paper 970340, 1997; Baert R., D.E. Beckman, A.W.M.J. Veen: ``EGR Technology for Lowest Emissions,'' SAE paper 964112, 1996; and, Heavy-duty Engine Working Group, Mobile Source Technical Advisory Subcommittee of the Clean Air Act Advisory Committee, ``Phase 2 of the EPA HDEWG Program--Summary Document'', available in EPA Air Docket A-98-32. \44\ See for example SAE paper 981035, ``The Cummins Signature 600 Heavy-Duty Diesel Engine'' T.R. Stover, D.H. Reichenbach, and E.K. Lifferth, Cummins Engine Co., Inc., Feb., 1998. --------------------------------------------------------------------------- In addition, as noted in section III.D, the fact that several heavy-duty diesel engine manufacturers have agreed to meet the 2004 standards in 2002 gives the Agency additional confidence that the NMHC+NOX standard being reaffirmed in today's proposal is appropriate for the 2004 model year. As discussed in section IX, and in the draft RIA, EPA does not believe more stringent standards for the 2004 model year are technologically feasible, giving appropriate consideration to cost, energy, and safety factors. Technologies which could reduce emissions significantly below the 2004 standards, such as NOX absorber catalysts, are still in the research and development stage, and do not appear to be ready for the 2004 model year. The Agency has also examined technologies to reduce PM from HD diesel engines, including diesel oxidation catalysts and particulate traps. As discussed in the draft RIA, we believe the current PM standard of 0.1 g/bhp-hr (0.05 for urban buses) continues to be the appropriate standard for the 2004 time frame. However, in section X of today's proposal we discuss the possible feasibility of more stringent standards in later model years, although no specific proposals are made today. B. Are Changes in Diesel Fuel Quality Necessary To Meet the 2004 Standards? The purpose of this section is to assess the current understanding of the role diesel fuel quality plays in the ability of diesel engines to meet the 2004 NMHC+NOX emission standards and to determine whether these standards can be met using currently available fuel. It has long been realized that diesel engine technology alone is not the only mechanism to lower NOX emissions. Diesel fuel quality also plays an important role in emission formation, as well as engine performance. In addition, diesel fuel quality can play a role in the effectiveness of certain emission control technologies, and in some cases can be considered a technology enabler, i.e., some emission control devices may not function because of certain diesel fuel properties, such as sulfur content. In EPA's 1997 final rulemaking for the 2004 standards, we stated that we believed the 2004 standards were appropriate and technologically feasible through diesel engine technology modifications alone, without changes to diesel fuel quality (see 62 FR 54700, Oct. 21, 1997). However, we also stated that this issue would be revisited in the 1999 technology review rulemaking. ``EPA will evaluate in light of any new information whether diesel fuel improvements are needed for the standards to be appropriate for 2004.'' (See 62 FR 54700, Oct. 21, 1997). Section V.A. of this preamble (``2004 Emission Standards for Heavy- duty Diesel Engines'') and Chapter 3 of the draft RIA for this proposal (``Technological Feasibility of HD Diesel and Otto-cycle Standards'') discuss in detail the technologies we believe will enable HD diesel engines to meet the 2004 standards, on existing U.S. HD diesel fuel. These technologies include cooled EGR, advanced fuel injection systems with rate-shaping ability, advanced turbocharger designs (such as variable nozzle turbochargers), and electronic engine management. These technologies have been demonstrated to produce significant emission reduction, independent of changes in current U.S. diesel fuel quality. Based on the information discussed in section V.A. of this preamble and Chapter 3 of the draft RIA, and based on the fact that these emission control technologies can produce substantial emission reductions using current diesel fuel, we conclude no change in diesel fuel quality is necessary to meet the 2004 NMHC+NOX standard. We request comment on this conclusion, and encourage commenters to supply any data and information that may support their comments. Engine manufacturers have recently raised concerns to EPA regarding the potential negative effects of current diesel fuel sulfur levels on engine durability for 2004 technology engines for the full useful life of the engines. As discussed in Chapter 3 of the draft RIA for this rule, the use of cooled EGR systems to meet the 2004 standards can give rise to potentially significant concentrations of sulfuric acid formation in the recirculated exhaust if the EGR system cools the exhaust below the water vapor dew point. In addition, some HD diesel engine manufacturers have expressed specific concern regarding the extended useful life for the heavy-heavy duty diesel service class which goes into effect in 2004. In the 1997 final rulemaking for on- highway heavy-duty diesel engines, EPA revised and extended the useful life for the heavy-heavy service class from 290,000 miles to 435,000 miles (see 62 FR 54700, October 21, 1997). Several manufacturers have suggested EPA should reconsider this useful life extension due to their concerns with engine durability, diesel fuel sulfur, and cooled EGR systems. These manufacturers have suggested EPA implement the extended useful life contingent upon federal diesel fuel standards meeting some threshold maximum fuel sulfur content. However, the Agency believes manufacturers will design cooled EGR systems to limit sulfuric acid formation and to prevent in-use durability problems. As [[Page 58485]] discussed in the RIA (section 3.II.B), EPA expects engine manufacturers to maintain EGR cooler systems slightly above the water vapor dew point, particularly at high load. In addition, EPA expects manufacturers to utilize EGR systems made of sulfuric acid corrosive resistant materials (such as specially treated stainless steel) to prevent deterioration of the EGR system. We request additional information and supporting data on the manufacturers' concerns regarding durability issues associated with the 2004 standards. We request specific comment and supporting data on the manufacturers' concerns, including any in-use or laboratory durability data, and any data which would support or refute the manufacturers' contentions regarding the need for a shorter useful life for the heavy-heavy service class. In the remainder of this section, we review the new information which has become available since the 1997 rulemaking through a study performed by the Heavy-duty Engine Working Group. In anticipation of the need for new information regarding the influence of diesel fuel quality on future emission technologies and achievable levels, in December of 1995 a new Working Group called the Heavy-duty Engine Working Group (HDEWG) was formed under the Mobile Source Technical Advisory Subcommittee of the Clean Air Act Advisory Committee. The HDEWG consists of approximately 30 members, including representatives from EPA, heavy-duty engine original equipment manufacturers (OEMs), the oil industry, state air quality agencies, private consultants and members of academic institutions. The HDEWG formed a steering committee which consisted of representatives from EPA, Cummins, Caterpillar, Navistar, Ford, British Petroleum, Equilon, Mobil Oil, Phillips, the Engine Manufacturers Association, the American Petroleum Institute, and the National Petroleum Refinery Association. The HDEWG set as their research objective to contribute to EPA's 1999 technology review of the NMHC+NOX emission standards for model year 2004 heavy-duty diesel engines by assessing relative merits of achieving 2.5 g/bhp-hr NMHC+NOX level either through engine system modifications alone, or a combination of engine system and fuel modifications. The HDEWG established a three phase process in order to meet their objective. In Phase 1, the goal was to determine whether the combined effects of diesel fuel properties on exhaust emissions of ``black box'',45 advanced prototype engines being developed by engine manufacturers were large enough to warrant a Phase 2. However, the details of each black box engine would not be shared with the HDEWG. In addition, the HDEWG agreed to use one ``transparent'' engine at an independent test facility, Southwest Research Institute (SwRI). During Phase 1, testing was to be performed on the transparent engine at SwRI, as well as the black box engines at manufacturers' own testing facilities, to determine if the transparent engine was representative of the black box engines with respect to diesel fuel effects on NOX emissions. Phase 2 of the program, which would occur upon successful completion of Phase 1, would be used to test a range of relevant fuel properties on the transparent engine at SwRI, in order to determine the effects of various fuel properties on emissions. Finally, Phase 3 of the test program would determine whether or not the results seen during Phase 2 on the transparent engine was in fact representative of black box engines, i.e., advanced prototype engines being developed by engine manufacturers to meet the 2004 standards. Phase 3 would be performed at engine manufacturers' laboratories using a subset of the fuel matrix from Phase 2. --------------------------------------------------------------------------- \45\ ``Black box'' engines are advanced engines being designed by engine manufacturers to meet the 2004 standards. --------------------------------------------------------------------------- At the time of the publication of this proposal, Phase 1 and Phase 2 of the program have been completed. Phase 3 is expected to be completed by the end of 1999. The RIA for this proposal contains a detailed discussion of the Phase 1 and Phase 2 portions of the HDEWG test program. The reader should see Chapter 3 of the draft RIA for this proposal for a detailed description. The HDEWG's primary focus was on the effects of diesel fuel properties on HC and NOX emissions, not on PM emissions, and therefore fuel sulfur level was not investigated. A significant amount of data exists on the effects of diesel fuel sulfur on engine emissions, and in fact this data was summarized recently in a paper published by members of the HDEWG.46 Existing data on recent model year HD engines indicates diesel fuel sulfur level does have a statistically significant effect on PM emissions, but no statistically significant effect on HC, carbon monoxide (CO), or NOX emissions for engines with no exhaust aftertreatment. For this reason, and because of the focus on NMHC and NOX emissions, as well as the limitations of the prototype SwRI transparent engine, the HDEWG did not include fuel sulfur level as a variable in Phase 1, 2 or 3 of their test program, nor were PM emissions measured during Phase 1 or 2. The Phase 3 test program, done at individual engine manufacturers' facilities, will include PM measurement. --------------------------------------------------------------------------- \46\ See Lee, R., Pedley, J., and Hobbs, C., ``Fuel Quality Impact On Heavy-Duty Diesel Emissions:--A Literature Review'', Society of Automotive Engineers paper number 982649, 1998. --------------------------------------------------------------------------- The HDEWG concluded two points based on the results of the Phase 1 testing. First, initial testing on a limited set of diesel fuel formulations (fuel batches with high cetane number and low aromatics) on advanced prototype engines by the engine manufacturers showed a change in NOX emissions which warranted additional testing under Phase 2. Second, the ``transparent'' engine at SwRI performed in a way that was representative of engine manufacturers' advanced prototypes, and was therefore an adequate test engine for Phase 2. The purpose of the Phase 2 component of the test program was to test a range of relevant fuel properties on the transparent engine at SwRI in order to determine the effects of various fuel properties on emissions. All testing during Phase 2 of the test program was done at SwRI on the transparent engine. Based on the results of the Phase 1 testing, as well as the literature review performed under Phase 1, the HDEWG selected four fuel properties for investigation under Phase 2: density, cetane (natural and ``boosted'' 47), monoaromatic content and polyaromatic content. As mentioned previously, fuel sulfur level was not investigated. A test matrix was designed to decouple these fuel properties from each other. The design matrix included two levels of density, monoaromatic hydrocarbons, polyaromatic hydrocarbons, and three levels of cetane, with duplicate test points for both natural and ``boosted'' cetane. The final matrix included eighteen test fuels, with density varying from 830 to 860 kg/m\3\, cetane numbers from 42 to 48 to 53, monoaromatic content from 10 to 25 percent, and polyaromatic content from 2.5 to 10 percent. The test cycle used by SwRI was the AVL 8-mode test. This steady-state test cycle, with associated weighting factors, has been shown in the past to correlate very well with NOX emissions measured over the U.S. heavy-duty federal test procedure (FTP). All emission tests were performed at least in duplicate. The transparent engine used a SwRI is a modern, heavy-heavy duty diesel engine with [[Page 58486]] electronically controlled unit injectors capable of meeting the U.S. 1998 model year emission standards. This engine was modified by SwRI with the addition of a prototype, low-pressure loop, cooled EGR system with manual control of EGR flow rates. For the Phase 2 test program, SwRI selected EGR rates necessary to approach an AVL 8-mode composite NOX level of 2.5g/hp-hr. --------------------------------------------------------------------------- \47\ Boosted cetane is achieved by the addition of a fuel additive, in this case ethylhexyl nitrate. --------------------------------------------------------------------------- The large quantity of test data generated by the test program was evaluated using statistical techniques in order to develop exhaust emission and fuel consumption prediction models based on the four fuel properties. All properties were evaluated using a significance level of five percent. The data generated during Phase 2 indicates that for engines utilizing advanced fuel injection and a cooled EGR system operating at emissions levels near the 2004 standards the effects of large changes in individual fuel properties on HC+NOX emissions are rather small, and for cetane number not statistically significant. A large decrease in fuel density, from 860 to 830 kg/ m3, or in monoaromatic content, from 25 to 10 percent, is predicted to result in a 4.3 percent decrease in HC+NOX emissions. A large decrease in polyaromatics content, from 10 to 2.5 percent, is predicted to result in a 2.3 percent decrease in HC+NOX emissions. The Phase 2 data was also analyzed to predict the combined effects from diesel fuel changes on emissions, not just single property changes. The Phase 2 model was used to predict the effect of fuel modifications from current, average U.S. on-highway diesel fuel to a ``cleaner'', reformulated diesel fuel, one with low density (830 kg/ m3), high cetane (52), low monoaromatics (10 percent), and low polyaromatics (2.5 percent). The Phase 2 model predicts this significant change in U.S. diesel fuel formulation would result in a 8.4 percent decrease in HC+NOX emissions. The Phase 3 results are currently not available. However, based on what has been seen in the Phase 1 and Phase 2 portions of this test program, we do not believe a change in diesel fuel formulation is required to make the 2004 model year NMHC+NOX standards technologically feasible and appropriate under the CAA. The data from the Phase 1 and 2 portions of the HDEWG does indicate that a change in diesel fuel formulation could provide for a small reduction in HC+NOX emissions from HD diesels, on the order of an 8 percent reduction. An assessment of the appropriateness of such a diesel fuel reformulation, beyond the 2004 standards with existing HD diesel fuel, is outside the scope of this rulemaking. C. Otto-Cycle Engine-Based Program We are proposing an NMHC+NOX standard for Otto-cycle engines for 2004 and later model years, but are limiting the applicability of this new standard to engines used in vehicles over 14,000 pounds GVWR and in incomplete vehicles. 48 (We are also proposing new vehicle standards for the remaining engines, as discussed in later sections.) We are not proposing to apply the vehicle standards to these engines at this time. Engines used in incomplete vehicles are manufactured for use in many different kinds of heavy-duty vehicles by many different manufacturers. Vehicles in the weight categories above 14,000 pounds GVWR tend to be quite large and varied compared to pick-up trucks and full-size vans, and most dynamometer test facilities are currently not equipped to accommodate vehicles in this size range. Additionally, this approach is consistent with California which allows engine-based testing for these vehicles in its Medium-duty Vehicle program. --------------------------------------------------------------------------- \48\ Incomplete vehicles less than 14,000 lbs GVWR could optionally certify to the proposed new vehicle standards, as discussed in a later section. --------------------------------------------------------------------------- 1. Engine Exhaust Emissions Standards We propose a NMHC+NOX standard of 1.0 g/bhp-hr for MY 2004 and later for those Otto-cycle engines in the engine-based program. The proposed standard represents a reduction in the NOX and HC standards of over 75 percent. EPA believes that this standard represents the most stringent standard reasonably achievable for these engines, in keeping with the requirements of the CAA. EPA's analysis of the technological feasibility of a 1.0 g/bhp-hr NMHC+NOX standard is contained in Technological Feasibility section below. We also believe that the ABT program proposed for engines provides manufacturers with the needed flexibility to meet the new standard as their product lines become subject to the new engine standards. The ABT provisions are also described below. In their assessment of the feasibility of new engine-based standards, engine manufacturers recommended a standard of 2.0 g/bhp-hr NMHC+NOX. The Technological Feasibility section also contains a discussion of the manufacturer's recommendations. EPA requests specific comment on a range of possible standards, from the proposed standard of 1.0 g/bhp-hr to 1.5 g/bhp-hr, and on the standard of 2.0 g/bhp-hr proposed by engine manufacturers. 2. Averaging, Banking, and Trading for Otto-Cycle Engines As part of proposing more stringent engine-based standards, EPA is proposing a modified ABT program for these engines. The program is similar in design to the program adopted for diesel engines. EPA is proposing ABT modifications to allow more flexibility within the ABT framework to help meet the more stringent standards. ABT credits can help manufacturers with engine configurations that are more difficult to modify, where more time would help reduce costs. Credits can also allow manufacturers to continue with product plans that might call for the retirement of an engine family at some point shortly after 2004. By banking credits manufacturers can also reduce their uncertainty or risk associated with the new standards. In the Summary and Analysis of Comments for the Diesel Final Rule, EPA explained why the modified ABT program adopted in that rulemaking will not decrease emissions reductions associated with the new standards. 49 Similarly, EPA believes that the modified ABT program proposed in this rulemaking also will not decrease emissions reductions associated with the new standards. --------------------------------------------------------------------------- \49\ See EPA Air Docket No. A-95-27. --------------------------------------------------------------------------- The ABT program has been used for only one Otto-cycle engine family to meet the current 4.0 g/bhp-hr NOX standard which went into effect in the 1998 model year. In other cases, advances in catalyst technology and engine/fuel system improvements have allowed manufacturers to meet the standard across their product line. Most engine families have certification levels of less than half the standard. However, with the proposed standard for 2004, EPA expects ABT to become a more important tool for Otto-cycle engine manufacturers. An ABT program allows the Agency to propose and finalize a more stringent engine standard than might otherwise be appropriate under the CAA, since ABT reduces the cost and improves the technological feasibility of achieving the standard. EPA is proposing changes to the ABT program with the intent that the changes would enhance the technological feasibility and cost-effectiveness of the new standard, and thereby help to ensure the new standard would be attainable earlier than would otherwise be possible. The changes would provide manufacturers with additional product planning flexibility and the opportunity for a more cost effective introduction of product lines [[Page 58487]] meeting the new standard. Also, EPA believes that ABT creates an incentive for early introduction of new technology which allows certain engine families to act as trail blazers for new technology. This can help provide valuable information to manufacturers on the technology prior to manufacturers needing to apply the technology throughout their product line. This further improves the feasibility of achieving the standard. This early introduction can also provide valuable information for use in other regulatory programs that may benefit from similar technologies (e.g., nonroad programs). EPA views the effect of the ABT program itself as environmentally neutral because the use of credits by some engines is offset by the generation of credits by other engines. However, when coupled with the new standards, the ABT program would be environmentally beneficial because it would allow the new standards to be implemented earlier than would otherwise be appropriate under the Act. EPA proposes the following provisions for the modified ABT program for Otto-cycle engines: Manufacturers could bank NOX credits beginning in MY 2000 for MYs 2004 and later. Credits would be earned up to a NOX level of 2.0 g/bhp-hr. Credits would be discounted by 10 percent for engine families with FELs above the 1.0 g/bhp-hr NMHC+NOX level (i.e., the proposed standard) and undiscounted for engine families with FELs at or below the 1.0 g cut point. For model year 2004 and later, engine families with FELs above 0.5 g/bhp-hr NMHC+NOX (i.e., one-half of the proposed standard) would be discounted by 10 percent. Engine families with FELs at or below 0.5 g/bhp-hr would earn undiscounted credits. As with the diesel program, NOX credits banked prior to 2004 would be used to meet the combined NMHC+NOX standard in 2004 and later. Credits banked under the modified program would have unlimited credit life. Engine families using credits after MY 2004 may not exceed the previous NOX standard of 4.0 g/bhp-hr. Engine families generating credits prior to 2004 must meet the revised requirements for deterioration factors noted above. Prior to 2004, manufacturers could continue to use the current ABT program. EPA proposes that the current program would end in 2004 and the modified program would remain. Only credits banked under the modified program could be used in 2004 and later. EPA is proposing to end the current program with the 2003 model year because of concern that manufacturers could generate enough credits under the current program to significantly delay the 2004 standards. The current program allows manufacturers to earn credits up to the current NOX standard of 4.0 g/bhp-hr. With most engines currently certified with NOX levels below 2.0 g/bhp-hr, there is potential for substantial credit generation without the application of improved technology under the current ABT program. If manufacturers were to bank these credits, they could potentially use them to delay the introduction of engines meeting the 2004 standards for a large majority of their sales for up to three years. The proposed 2.0 g/bhp-hr ceiling for credit generation in the modified program provides opportunity for manufacturers to earn credits through the use of emissions controls that are superior to the average controls currently being used. EPA believes this approach is consistent with the goals of ABT. EPA requests comment on the proposed 2.0 g/bhp-hr ceiling and on other alternatives for transitioning from the current 4.0 g/bhp-hr NOX standard to the 1.0 g/bhp-hr NOX standard proposed for 2004. One such alternative could be a phase down of the credit generation trigger value during the model years prior to 2004, rather than a single trigger point of 2.0 g/bhp-hr. The changes to credit life and discounting being proposed for Otto- cycle engines are conceptually consistent with the modifications finalized for diesel engines. EPA is proposing to discount credits by 10 percent if the engine has an FEL above a certain value or cut-point. EPA adopted cut points in the diesel program in order to identify the introduction of new technology as opposed to recalibrating or enhancing existing technology. EPA believes that adoption of cutpoints in the HD Otto-cycle engine program will provide similar technology forcing incentives. EPA selected cut-point levels which represent a clear step in emissions control rather than a marginal emissions reduction. The 10 percent discount selected for the HD Otto-cycle engine ABT program is consistent with the program finalized for diesel engines. In that final rule, EPA noted that a 10 percent discount strikes a balance between zero (which significantly reduces the incentive to develop and implement significantly cleaner technology) and 20 percent (which manufacturers indicated in comments was far too large and would create a disincentive for the introduction of cleaner technology). (See 62 FR 54708, October 21, 1997.) EPA requests comment on the selected levels of the cut-points and discount adjustment, including comments on whether a phased-in approach with a decreasing cut-point would be appropriate for this category of engines. For diesels, EPA removed the three year credit life limit which allows manufacturers to earn credits to be used in 2004 and later as early as the 1998 model year. For Otto-cycle engines, MY 2000 will be the earliest model year in which the rule would be effective due to the timing of the rulemaking. Removing the credit life limit will provide an additional year of potential credit banking and allows manufacturers to retain credits after 2004 rather than having them expire after a certain year. We believe that having credits expire would simply encourage manufacturers to use the credits rather than save them; thus, removing the credit life limit should provide a net environmental benefit.50 --------------------------------------------------------------------------- \50\ EPA presented a detailed analysis of its ABT program in the Summary and Analysis of Comments for the Diesel Final Rule, Docket A-95-27, document No. V-C-01. -------- [Text truncated at 120,000 characters. The full text is on the page linked above.] --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A99-26795. Public record. Not legal advice.