# Control of Emissions of Air Pollution From Nonroad Diesel Engines and Fuel > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A03-9737 ## Record - **Collection:** Federal Register - **Document type:** Proposed Rule - **Published:** May 23, 2003 - **Citation:** 68 FR 28328 ## Text Part II Environmental Protection Agency ----------------------------------------------------------------------- 40 CFR Parts 69, 80, 89, et al. Control of Emissions of Air Pollution From Nonroad Diesel Engines and Fuel; Proposed Rule Federal Register / Vol. 68, No. 100 / Friday, May 23, 2003 / Proposed Rules [[Page 28328]] ----------------------------------------------------------------------- ENVIRONMENTAL PROTECTION AGENCY 40 CFR Parts 69, 80, 89, 1039, 1065, and 1068 [AMS-FRL-7485-8] RIN 2060-AK27 Control of Emissions of Air Pollution From Nonroad Diesel Engines and Fuel AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of proposed rulemaking. ----------------------------------------------------------------------- SUMMARY: Nonroad diesel engines contribute considerably to our nation's air pollution. These engines, used primarily in construction, agricultural, and industrial applications, are projected to continue to contribute large amounts of particulate matter (PM), nitrogen oxides (NOX), and sulfur oxides (SOX), all of which contribute to serious public health problems in the United States. These problems include premature mortality, aggravation of respiratory and cardiovascular disease, aggravation of existing asthma, acute respiratory symptoms, chronic bronchitis, and decreased lung function. We believe that diesel exhaust is likely to be carcinogenic to humans by inhalation. Today EPA is proposing new emission standards for nonroad diesel engines and sulfur reductions in nonroad diesel fuel that will dramatically reduce emissions attributed to nonroad diesel engines. This comprehensive national program will regulate nonroad diesel engines and diesel fuel as a system. New engine standards will begin to take effect in the 2008 model year. These standards are based on the use of advanced exhaust emission control devices. We estimate PM reductions of 95%, NOX reductions of 90%, and the virtual elimination of sulfur oxides (SOX) from nonroad engines meeting the new standards. Nonroad diesel fuel sulfur reductions of up to 99% from existing levels will provide significant health benefits as well as facilitate the introduction of high-efficiency catalytic exhaust emission control devices as these devices are damaged by sulfur. These fuel controls would begin in mid-2007. Today's nonroad proposal is largely based on EPA's 2007 highway diesel program. To better ensure the benefits of the standards are realized in-use and throughout the useful life of these engines, we are also proposing new test procedures, including not-to-exceed requirements, and related certification requirements. The proposal also includes provisions to facilitate the transition to the new engine and fuel standards and to encourage the early introduction of clean technologies and clean nonroad diesel fuel. We have also developed provisions for both the proposed engine and fuel programs designed to address small business considerations. The requirements in this proposal would result in substantial benefits to public health and welfare and the environment through significant reductions in emissions of NOX and PM, as well as nonmethane hydrocarbons (NMHC), carbon monoxide (CO), sulfur oxides (SOX) and air toxics. We project that by 2030, this program would reduce annual emissions of NOX, and PM by 827,000 and 127,000 tons, respectively. These emission reductions would prevent 9,600 premature deaths, over 8,300 hospitalizations, and almost a million work days lost, and other quantifiable benefits every year. All told the benefits of this rule would be approximately $81 billion annually by 2030. Costs for both the engine and fuel requirements would be many times less, at approximately $1.5 billion annually. DATES: Comments: Send written comments on this proposal by August 20, 2003. See section IX for more information about written comments. Hearings: We will hold public hearings on the following dates: June 10, 2003; June 12, 2003; and June 17, 2003. Each hearing will start at 9 a.m. local time. If you want to testify at a hearing, notify the contact person listed below at least 10 days before the hearing. See section IX for more information about public hearings. ADDRESSES: Comments: Comments may be submitted by mail to: Air Docket, Environmental Protection Agency, Mailcode: 6102T, 1200 Pennsylvania Ave., NW., Washington, DC 20460, Attention Docket ID No. A-2001-28. Comments may also be submitted electronically, by facsimile, or through hand delivery/courier. Follow the detailed instructions as provided in section IX of the SUPPLEMENTARY INFORMATION section. Hearings: We will hold public hearings at the following three locations: ------------------------------------------------------------------------ ------------------------------------------------------------------------ New York, New York, Park Central New York, June 10, 2003 870 Seventh Avenue at 56th Street, New York, NY 10019, Telephone: (212) 247-8000, Fax: (212) 541-8506. Chicago, Illinois, Hyatt Regency O'Hare, 9300 June 12, 2003. W. Bryn Mawr Avenue, Rosemont, IL 60018, Telephone: (847) 696-1234, Fax: (847) 698- 0139. Los Angeles. California, Hyatt Regency Los June 17, 2003. Angeles, 711 South Hope Street, Los Angeles, California, USA. 90017, Telephone: (213) 683- 1234, Fax: (213) 629-3230. ------------------------------------------------------------------------ See section IX, ``Public Participation'' below for more information on the comment procedure and public hearings. FOR FURTHER INFORMATION CONTACT: U.S. EPA, Office of Transportation and Air Quality, Assessment and Standards Division hotline, (734) 214-4636, [email protected]. Carol Connell, (734) 214-4349; [email protected]. SUPPLEMENTARY INFORMATION: Regulated Entities This action would affect you if you produce or import new heavy- duty diesel engines which are intended for use in nonroad vehicles such as agricultural and construction equipment, or produce or import such nonroad vehicles, or convert heavy-duty vehicles or heavy-duty engines used in nonroad vehicles to use alternative fuels. It would also affect you if you produce, import, distribute, or sell nonroad diesel fuel, or sell nonroad diesel fuel. The following table gives some examples of entities that may have to follow the regulations. But because these are only examples, you should carefully examine the regulations in 40 CFR parts 80, 89, 1039, 1065, and 1068. If you have questions, call the person listed in the FOR FURTHER INFORMATION CONTACT section of this preamble: -------------------------------------------------------------------------------------------------------------------------------------------------------- NAICS SIC Category codes codes Examples of potentially regulated entities \a\ \b\ -------------------------------------------------------------------------------------------------------------------------------------------------------- Industry...................................... 333618 3519 Manufacturers of new nonroad diesel engines. [[Page 28329]] Industry...................................... 333111 3523 Manufacturers of farm machinery and equipment. Industry...................................... 333112 3524 Manufacturers of lawn and garden tractors (home). Industry...................................... 333924 3537 Manufacturers of industrial trucks. Industry...................................... 333120 3531 Manufacturers of construction machinery. Industry...................................... 333131 3532 Manufacturers of mining machinery and equipment. Industry...................................... 333132 3533 Manufacturers of oil and gas field machinery and equipment. Industry...................................... 811112 7533 Commercial importers of vehicles and vehicle components. 811198 7549 Industry...................................... 324110 2911 Petroleum refiners. Industry...................................... 422710 5171 Diesel fuel marketers and distributors. 422720 5172 Industry...................................... 484220 4212 Diesel fuel carriers. 484230 4213 -------------------------------------------------------------------------------------------------------------------------------------------------------- \a\ North American Industry Classification System (NAICS). \b\ Standard Industrial Classification (SIC) system code. How Can I Get Copies of This Document and Other Related Information? Docket. EPA has established an official public docket for this action under Docket ID No. A-2001-28. The official public docket consists of the documents specifically referenced in this action, any public comments received, and other information related to this action. Although a part of the official docket, the public docket does not include Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. The official public docket is the collection of materials that is available for public viewing at the Air Docket in the EPA Docket Center, (EPA/DC) EPA West, Room B102, 1301 Constitution Ave., NW., Washington, DC. The EPA Docket Center Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Reading Room is (202) 566-1742, and the telephone number for the Air Docket is (202) 566-1742. Electronic Access. You may access this Federal Register document electronically through the EPA Internet under the ``Federal Register'' listings at http://www.epa.gov/fedrgstr/. An electronic version of the public docket is available through EPA's electronic public docket and comment system, EPA Dockets. You may use EPA Dockets at http://www.epa.gov/edocket/ to submit or view public comments, access the index listing of the contents of the official public docket, and to access those documents in the public docket that are available electronically. Once in the system, select ``search,'' then key in the appropriate docket identification number. Certain types of information will not be placed in the EPA Dockets. Information claimed as CBI and other information whose disclosure is restricted by statute, which is not included in the official public docket, will not be available for public viewing in EPA's electronic public docket. EPA's policy is that copyrighted material will not be placed in EPA's electronic public docket but will be available only in printed, paper form in the official public docket. To the extent feasible, publicly available docket materials will be made available in EPA's electronic public docket. When a document is selected from the index list in EPA Dockets, the system will identify whether the document is available for viewing in EPA's electronic public docket. Although not all docket materials may be available electronically, you may still access any of the publicly available docket materials through the docket facility identified in section IX. For public commenters, it is important to note that EPA's policy is that public comments, whether submitted electronically or in paper, will be made available for public viewing in EPA's electronic public docket as EPA receives them and without change, unless the comment contains copyrighted material, CBI, or other information whose disclosure is restricted by statute. When EPA identifies a comment containing copyrighted material, EPA will provide a reference to that material in the version of the comment that is placed in EPA's electronic public docket. The entire printed comment, including the copyrighted material, will be available in the public docket. Public comments submitted on computer disks that are mailed or delivered to the docket will be transferred to EPA's electronic public docket. Public comments that are mailed or delivered to the Docket will be scanned and placed in EPA's electronic public docket. Where practical, physical objects will be photographed, and the photograph will be placed in EPA's electronic public docket along with a brief description written by the docket staff. For additional information about EPA's electronic public docket visit EPA Dockets online or see 67 FR 38102, May 31, 2002. Outline of This Preamble I. Overview A. What Is EPA Proposing? 1. Nonroad Diesel Engine Emission Standards 2. Nonroad, Locomotive, and Marine Diesel Fuel Quality Standards B. Why Is EPA Making This Proposal? 1. Nonroad, Locomotive, and Marine Diesels Contribute to Serious Air Pollution Problems 2. Technology and Fuel Based Solutions 3. Basis For Action Under the Clean Air Act II. What Is the Air Quality Impact of the Sources Covered by the Proposed Rule? A. Overview B. Public Health Impacts 1. Particulate Matter a. Health Effects of PM2.5 and PM10 b. Current and Projected Levels i. PM10 Levels ii. PM2.5 Levels 2. Air Toxics a. Diesel exhaust i. Potential Cancer Effects of Diesel Exhaust ii. Other Health Effects of Diesel Exhaust iii. Ambient Levels and Exposure to Diesel Exhaust PM iv. Diesel Exhaust PM Exposures b. Gaseous Air Toxics 3. Ozone a. What are the health effects of ozone pollution? b. Current and projected 8-hour ozone levels C. Other Environmental Effects 1. Visibility a. Visibility is Impaired by Fine PM and Precursor Emissions From Nonroad Engines Subject to this Proposed Rule b. Visibility Impairment Where People Live, Work and Recreate [[Page 28330]] c. Visibility Impairment in Mandatory Federal Class I Areas 2. Acid Deposition 3. Eutrophication and Nitrification 4. Polycyclic Organic Matter Deposition 5. Plant Damage from Ozone D. Other Criteria Pollutants Affected by This NPRM E. Emissions From Nonroad Diesel Engines 1. PM2.5 2. NOX 3. SO2 4. VOC and Air Toxics III. Nonroad Engine Standards A. Why are We Setting New Engine Standards? 1.The Clean Air Act and Air Quality 2. The Technology Opportunity for Nonroad Diesel Engines B. What Engine Standards are We Proposing? 1. Exhaust Emissions Standards a. Standards Timing b. Phase-In of NOX and NMHC Standards c. Rationale for Restructured Horsepower Categories d. PM Standards for Smaller Engines i. X and PM Emissions From Mobile Source Diesel Engines a. PM Control Technologies b. NOX Control Technologies 2. Can These Technologies Be Applied to Nonroad Engines and Equipment? a. Nonroad Operating Conditions and Exhaust Temperatures b. Nonroad Operating Conditions and Durability 3. Are the Standards Proposed for Engines of 75 hp or Higher Feasible? 4.Are the Standards Proposed for Engines =25 hp and X standards 5. Are the Standards Proposed for Engines X standards for engines X Catalysts and the Need for Low Sulfur Fuel a. Sulfur Poisoning (Sulfate Storage) on NOX Adsorbers b. Sulfate Particulate Production and Sulfur Impacts on Effectiveness of NOX Control Technologies G. Reassessment of Control Technology for Engines Less Than 75 hp in 2007 IV. Our Proposed Program for Controlling Nonroad, Locomotive and Marine Diesel Fuel Sulfur A. Proposed Nonroad, Locomotive and Marine Diesel Fuel Quality Standards 1. What Fuel Is Covered by this Proposal? 2. Standards and Deadlines for Refiners, Importers, and Fuel Distributors a. The First Step to 500 ppm b. The Second Step to 15 ppm c. Other Standard Provisions d. Cetane Index or Aromatics Standard B. Program Design and Structure 1. Background 2. Proposed Fuel Program Design and Structure a. Program Beginning June 1, 2007 i. Use of a Marker To Differentiate Heating Oil from NRLM ii. Non-highway Distillate Baseline Cap iii. Setting the Non-highway Distillate Baseline iv. Diesel Sulfur Credit Banking, and Trading Provisions for 2007 b. 2010 i. A Marker To Differentiate Locomotive and Marine Diesel from Nonroad Diesel ii. Diesel Sulfur Credit Banking and Trading Provisions for 2010 c. 2014 3. Other Options Considered a. Highway Baseline and a NRLM baseline for 2007 i. Highway Baseline ii. Nonroad, Locomotive, and Marine Baseline iii. Combined Impact of Highway and NRLM Baselines b. Locomotive and Marine Baseline for 2010 c. Designate and Track Volumes in 2007 i. Replacement for the Non-highway Baseline Approach ii. Designate and Track as a Refiners Option in Addition to the Baseline Approach C. Hardship Provisions for Qualifying Refiners 1. Hardship Provisions for Qualifying Small Refiners a. Qualifying Small Refiners i. Regulatory Flexibility for Small Refiners ii. Rationale for Small Refiner Provisions iii. Limited Impact of Small Refiner Options on Program Emissions Benefits b. How Do We Define Small Refiners for Purposes of the Hardship Provisions? c. What Options Are Available for Small Refiners? i. Delays in Nonroad Fuel Sulfur Standards for Small Refiners ii. Options to Encourage Earlier Compliance by Small Refiners d. How Do Refiners Apply for Small Refiner Status? 2. General Hardship Provisions a. Temporary Waivers From Non-highway Diesel Sulfur Requirements in Extreme Unforeseen Circumstances b. Temporary Waivers Based on Extreme Hardship Circumstances D. Should Any Individual States or Territories Be Excluded From This Rule? 1. Alaska a. How Was Alaska Treated Under the Highway Diesel Standards? b. What Nonroad Standards Do We Propose for Urban Areas of Alaska? c. What Do We Propose for Rural Areas of Alaska? 2. American Samoa, Guam, and the Commonwealth of Northern Mariana Islands a. What Provisions Apply in American Samoa, Guam, and the Commonwealth of Northern Mariana Islands? b. Why Are We Treating These Territories Uniquely? E. How Are State Diesel Fuel Programs Affected by the Sulfur Diesel Program? F. Technological Feasibility of the 500 and 15 ppm Sulfur Diesel Fuel Program 1. What Is the Nonroad, Locomotive and Marine Diesel Fuel Market Today? 2. How Do Nonroad, Locomotive and Marine Diesel Fuel Differ From Highway Diesel Fuel? 3. What Technology Would Refiners Use To Meet the Proposed 500 ppm Sulfur Cap? 4. Has Technology To Meet a 500 ppm Cap Been Commercially Demonstrated? 5. Availability of Leadtime To Meet the 2007 500 ppm Sulfur Cap 6. What Technology Would Refiners Use To Meet the Proposed 15 ppm Sulfur Cap for Nonroad Diesel Fuel? 7. Has Technology To Meet a 15 ppm Cap Been Commercially Demonstrated? 8. Availability of Leadtime To Meet the 2010 15 ppm Sulfur Cap 9. Feasibility of Distributing Nonroad, Locomotive and Marine Diesel Fuels That Meet the Proposed Sulfur Standards a. Limiting Sulfur Contamination b. Potential Need for Additional Product Segregation G. What Are the Potential Impacts of the 15 ppm Sulfur Diesel Program on Lubricity and Other Fuel Properties? 1. What Is Lubricity and Why Might It Be a Concern? 2. A Voluntary Approach on Lubricity [[Page 28331]] 3. What Other Impact Would Today's Actions Have on the Performance of Diesel and Other Fuels? H. Refinery Air Permitting V. Economic Impacts A. Refining and Distribution Costs 1. Refining Costs 2. Cost of Lubricity Additives 3. Distribution Costs 4. How EPA's Projected Costs Compare to Other Available Estimates 5. Supply of Nonroad, Locomotive and Marine Diesel Fuel 6. Fuel Prices B. Cost Savings to the Existing Fleet From the Use of Low Sulfur Fuel C. Engine and Equipment Cost Impacts 1. Engine Cost Impacts a. Engine Fixed Costs i. Engine and Emission Control Device R&D ii. Engine-Related Tooling Costs iii. Engine Certification Costs b. Engine Variable Costs i. NOX Adsorber System Costs ii. Catalyzed Diesel Particulate Filter (CDPF) Costs iii. CDPF Regeneration System Costs iv. Closed-Crankcase Ventilation System (CCV) Costs v. Variable Costs for Engines Below 75 Horsepower and Above 750 Horsepower c. Engine Operating Costs 2. Equipment Cost Impacts a. Equipment Fixed Costs b. Equipment Variable Costs 3. Overall Engine and Equipment Cost Impacts D. Annual Costs and Cost Per Ton 1. Annual Costs for the 500 ppm Fuel Program 2. Cost Per Ton for the 500 ppm Fuel Program 3. Annual Costs for the Proposed Two-Step Fuel Program and Engine Program 4. Cost per Ton of Emissions Reduced for the Total Program 5. Comparison With Other Means of Reducing Emissions E. Do the Benefits Outweigh the Costs of the Standards? 1. What were the results of the benefit-cost analysis? 2. What was our overall approach to the benefit-cost analysis? 3. What are the significant limitations of the benefit-cost analysis? F. Economic Impact Analysis 1. What is an Economic Impact Analysis? 2. What is EPA's Economic Analysis Approach for This Proposal? 3. What Are the Results of This Analysis? a. Expected Market Impacts b. Expected Welfare Impacts VI. Alternative Program Options A. Summary of Alternatives B. Introduction of 15 ppm Nonroad Diesel Sulfur Fuel in One Step 1. Description of the One-Step Alternative 2. Engine Emission Impacts 3. Fuel Impacts 4. Emission and Benefit Impacts C. Applying 15 ppm Requirement to Locomotive and Marine Diesel Fuel D. Other Alternatives VII. Requirements for Engine and Equipment Manufacturers A. Averaging, Banking, and Trading 1. Are we proposing to keep the ABT program for nonroad diesel engines? 2. What are the provisions of the proposed ABT program? 3. Should we expand the nonroad ABT program to include credits from retrofit of nonroad engines? a. What would be the environmental impact of allowing ABT nonroad retrofit credits? b. How would EPA ensure compliance with retrofit emissions standards? c. What is the legal authority for a nonroad ABT retrofit program? B. Transition Provisions for Equipment Manufacturers 1. Why are we proposing transition provisions for equipment manufacturers? 2. What transition provisions are we proposing for equipment manufacturers? a. Percent-of-Production Allowance b. Small-Volume Allowance c. Hardship Relief Provision d. Existing Inventory Allowance 3. What are the recordkeeping, notification, reporting, and labeling requirements associated with the equipment manufacturer transition provisions? a. Recordkeeping Requirements for Engine and Equipment Manufacturers b. Notification Requirements for Equipment Manufacturers c. Reporting Requirements for Engine and Equipment Manufacturers d. Labeling Requirements for Engine and Equipment Manufacturers 4. What are the proposed requirements associated with use of transition provisions for equipment produced by foreign manufacturers? C. Engine and Equipment Small Business Provisions (SBREFA) 1. Nonroad Diesel Small Engine Manufacturers a. Lead Time Transition Provisions for Small Engine Manufacturers i. What the Panel Recommended ii. What EPA Is Proposing b. Hardship Provisions for Small Engine Manufacturers i. What the Panel Recommended ii. What EPA Is Proposing c. Other Small Engine Manufacturer Issues i. What the Panel Recommended ii. What EPA Is Proposing 2. Nonroad Diesel Small Equipment Manufacturers a. Transition Provisions for Small Equipment Manufacturers i. What the Panel Recommended ii. What EPA Is Proposing b. Hardship Provisions for Small Equipment Manufacturers i. What the Panel Recommended ii. What EPA is Proposing D. Phase-In Provisions E. What Might Be Done To Encourage Innovative Technologies? 1. Incentive Program for Early or Very Low Emission Engines 2. Continuance of the Existing Blue Sky Program F. Provisions for Other Test and Measurement Changes 1. Supplemental Transient Test 2. Cold Start Testing 3. Control of Smoke 4. Steady-State Testing 5. Maximum Test Speed 6. Improvements to the Test Procedures G. Not-To-Exceed Requirements H. Certification Fuel I. Labeling and Notification Requirements J. Temporary In-Use Compliance Margins K. Defect Reporting L. Rated Power M. Hydrocarbon Measurement and Definition N. Auxiliary Emission Control Devices and Defeat Devices O. Other Issues VIII. Nonroad Diesel Fuel Program: Compliance and Enforcement Provisions A. Fuel Covered and Not Covered by This Proposal 1. Covered Fuel 2. Special Fuel Provisions and Exemptions a. Fuel Used in Military Applications b. Fuel Used in Research and Development c. Fuel Used in Racing Equipment d. Fuel for Export B. Additional Requirements for Refiners and Importers 1. Transfer of Credits 2. Additional Provisions for Importers and Foreign Refiners Subject to the Credit Provisions or Hardship Provisions 3. Proposed Provisions for Transmix Facilities 4. Highway or Nonroad Diesel Fuel Treated as Blendstock (DTAB) C. Requirements for Parties Downstream of the Refinery or Import Facility 1. Product Segregation and Contamination a. The Period From June 1, 2007 Through May 31, 2010 b. The Period From June 1, 2010 Through May 31, 2014 c. After May 31, 2014 2. Diesel Fuel Pump Labeling To Discourage Misfueling a. Pump Labeling Requirements 2006 b. Pump Labeling Requirements 2007-2010 c. Pump Labeling Requirements 2010-2014 d. Pump Labeling Requirements Beginning June 1, 2014 e. Nozzle Size Requirements or Other Requirements To Prevent Misfueling 3. Use of Used Motor Oil in New Nonroad Diesel Equipment 4. Use of Kerosene in Diesel Fuel 5. Use of Diesel Fuel Additives 6. End User Requirements 7. Anti-Downgrading Provisions D. Diesel Fuel Sulfur Sampling and Testing Requirements 1. Testing Requirements a. Test Method Approval, Recordkeeping, and Quality Control Requirements i. How Can a Given Method Be Approved? ii. What Information Would Have To Be Reported to the Agency? iii. What Quality Control Provisions Would Be Required? b. Requirements To Conduct Fuel Sulfur Testing. 2. Two Part-Per-Million Downstream Sulfur Measurement Adjustment 3. Sampling Requirements 4. Alternative Sampling and Testing Requirements for Importers of Diesel [[Page 28332]] Fuel Who Transport Diesel Fuel by Tanker Truck E. Fuel Marker Test Method 1. How Can a Given Marker Test Method Be Approved? 2. What Information Would Have To Be Reported to the Agency? F. Requirements for Recordkeeping, Reporting, and Product Transfer Documents 1. Registration of Refiners and Importers 2. Application for Small Refiner Status 3. Applying for Refiner Hardship Relief 4. Applying for a Non-Highway Distillate Baseline Percentage 5. Pre-Compliance Reports 6. Annual Compliance Reports and Batch Reports for Refiners and Importers 7. Product Transfer Documents (PTDs) a. The Period From June 1, 2007 Through May 31, 2010 b. The Period from June 1, 2010 Through May 31, 2014 c. The Period After May 31, 2014 d. Kerosene and Other Distillates To Reduce Viscosity e. Exported Fuel f. Additives 8. Recordkeeping Requirements 9. Record Retention G. Liability and Penalty Provisions for Noncompliance 1. General 2. What Are the Proposed Liability Provisions for Additive Manufacturers and Distributors, and Parties That Blend Additives Into Diesel Fuel? a. General b. Liability When the Additive Is Designated as Complying With the 15 ppm Sulfur Standard c. Liability When the Additive Is Designated as Having a Possible Sulfur Content Greater Than 15 ppm H. How Would Compliance With the Sulfur Standards Be Determined? IX. Public Participation A. How and to Whom Do I Submit Comments? 1. Electronically i. EPA Dockets ii. E-mail iii. Disk or CD ROM 2. By Mail 3. By Hand Delivery or Courier B. How Should I Submit CBI to the Agency? C. Will There Be a Public Hearing? D. Comment Period E. What Should I Consider as I Prepare My Comments for EPA? X. Statutory and Executive Order Reviews A. Executive Order 12866: Regulatory Planning and Review B. Paperwork Reduction Act C. Regulatory Flexibility Act (RFA), as Amended by the Small Business Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 U.S.C. 601 et. seq 1. Overview 2. Background 3. Summary of Regulated Small Entities a. Nonroad Diesel Engine Manufacturers b. Nonroad Diesel Equipment Manufacturers c. Nonroad Diesel Fuel Refiners d. Nonroad Diesel Fuel Distributors and Marketers 4. Potential Reporting, Record Keeping, and Compliance 5. Relevant Federal Rules 6. Summary of SBREFA Panel Process and Panel Outreach a. Significant Panel Findings b. Panel Process c. Transition Flexibilities i. Nonroad Diesel Engines ii. Nonroad Diesel Equipment iii. Nonroad Diesel Fuel Refiners iv. Nonroad Diesel Fuel Distributors and Marketers D. Unfunded Mandates Reform Act E. Executive Order 13132: Federalism F. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments G. Executive Order 13045: Protection of Children From Environmental Health and Safety Risks H. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution, or Use I. National Technology Transfer Advancement Act J. Plain Language XI. Statutory Provisions and Legal Authority I. Overview Nonroad diesel engines are the largest remaining contributor to the overall mobile source emissions inventory. We have already taken steps to dramatically reduce emissions from light-duty vehicles and heavy- duty vehicles and engines through the Tier 2 and 2007 highway diesel programs.\1\ With expected growth in the nonroad sector, the relative emissions contribution from nonroad diesel engines is projected to be even larger in future years. This proposed rule sets out emissions standards for nonroad diesel engines used mainly in construction, agricultural, industrial, and mining operations that will achieve reductions in PM and NOX emissions levels from today's engines in excess of 95% and 90%, respectively. Nonroad diesel fuel is currently unregulated. This proposal represents the first time nonroad diesel fuel will be regulated. We are proposing to reduce sulfur levels in nonroad diesel fuel by more than 99 percent to 15 parts per million (ppm). Taken together, controls included in this proposal would result in large public health and welfare benefits. --------------------------------------------------------------------------- \1\ See 65 FR 6698 (February 10, 2000) and 66 FR 5001 (January 18, 2001) for the final rules regarding the Tier 2 and 2007 highway diesel programs, respectively. --------------------------------------------------------------------------- The proposed standards for nonroad diesel engines and sulfur reductions for nonroad diesel fuel represent a dramatic step in emissions control, based on the use of advanced emissions control technology. Until the mid-90's, these engines had no emissions requirements. As a comparison, cars and trucks have been subject to a series of increasingly stringent emissions control programs since the 1970s. In terms of fuel quality requirements, nonroad diesel fuel is currently uncontrolled at the Federal level. EPA has already issued rules ending these disparities for diesel engines used in highway applications. Starting in 2007, these engines will meet standards of the same level of stringency as comparable gasoline vehicles, based on the use of advanced aftertreatment technologies and ultra low sulfur diesel fuel (containing no more than 15 ppm sulfur). This proposal is largely based on the performance of the same advanced aftertreatment technologies, and would bring nonroad diesel fuel to the same 15 ppm cap for sulfur that will be required for highway diesel fuel starting in 2006. We believe it is highly appropriate to propose dramatic steps forward in emissions standards and reductions in sulfur levels in nonroad diesel fuel. As discussed throughout this proposal, such steps represent a feasible progression in the application of advanced emissions control technologies, would achieve needed production of low sulfur diesel fuel to enable the advanced emission control technologies, the standards are cost-effective, and provide very large public health and welfare benefits. We followed certain principles when developing the elements of this proposal. First, the program must achieve reductions in NOX, SOx, and PM emissions as early as possible. This includes reductions from the in-use fleet of nonroad diesel engines. Second, as we did in the 2007 highway diesel program, we are treating vehicles and fuels as a system since we believe this is the best way to achieve the greatest emissions reductions. Third, the implementation of low sulfur requirements for nonroad diesel fuel must in no way interfere with the implementation and expected benefits of introducing ultra low sulfur fuel in the highway market, as required by the 2007 highway diesel program. Lastly, the program must provide sufficient lead time to allow the integration of advanced emissions control technologies from the highway sector onto nonroad diesel engines as well as the expansion of ultra low sulfur fuel production to the nonroad market. This proposal sets out new engine exhaust emissions standards, emissions test procedures, including not-to-exceed requirements, for nonroad engines, and sulfur control requirements for nonroad, locomotive, and marine diesel fuel. The proposed exhaust standards would [[Page 28333]] result in particulate matter (PM) and nitrogen oxide (NOX) emissions levels that are in excess of 95 percent and 90 percent, respectively, below comparable levels in effect today. They will begin to take effect in the 2008 model year, with a phase-in of standards across five different engine power rating groupings. New engine emissions test procedures are proposed to take effect with these new standards to better ensure emissions control over real-world engine operation and to help provide for effective compliance determination. Diesel fuel used in nonroad, locomotive, and marine applications would meet a 500 ppm cap starting in June 2007, a reduction of approximately 90%. There are large benefits to taking this first sulfur reduction action, especially in the reduction of particulate matter from the in- use fleet. In 2010, sulfur levels in nonroad diesel fuel (though not locomotive or marine diesel fuel) would meet a 15 ppm cap, for a total reduction of over 99%. While there are important health and welfare benefits associated with the reduction from 500 ppm to 15 ppm, the main benefit will be to facilitate the introduction of advanced aftertreatment devices on nonroad engines, which would in turn lead to significant benefits. We are also seeking comment on and seriously considering applying the 15 ppm cap to locomotive and marine diesel fuel. The requirements in this proposal would result in substantial benefits to public health and welfare and the environment through significant reductions in emissions of NOX and PM, as well as nonmethane hydrocarbons (NMHC), carbon monoxide (CO), sulfur oxides (SOX) and air toxics. We project that by 2030, this program would reduce annual emissions of NOX, and PM by 827,000, and 127,000 tons, respectively. These annual emission reductions would prevent 9,600 premature deaths, over 8,300 hospitalizations, and almost a million work days lost, among quantifiable benefits. The overall quantifiable benefits of this rule would be approximately $81 billion annually by 2030. Costs for both the engine and fuel requirements would be significantly less, at approximately $1.5 billion annually. A. What Is EPA Proposing? This proposal is a further step in EPA's long-term program to control emissions from nonroad diesel engines. The EPA has taken measures to reduce harmful emissions from nonroad diesel engines in two past regulatory actions. A 1994 final rule, developed under provisions of section 213 of the Clean Air Act, set initial emissions standards for new nonroad diesel engines greater than 50 hp (59 FR 31306, June 17, 1994). These standards gained modest reductions in NOX emissions and are referred to as EPA's ``Tier 1'' standards for large nonroad engines. A subsequent final rule published in 1998 set more stringent Tier 2 and Tier 3 standards for these engines, as well as Tier 1 and Tier 2 standards for the nonroad diesel engines under 50 hp (63 FR 56968, October 23, 1998). Nonroad diesel fuel quality is not presently regulated by the EPA. We also expressed our intent in the 1998 final rule to continue evaluating the rapidly changing state of diesel emissions control technology, and to perform a review in the 2001 timeframe of the technological feasibility of the Tier 3 standards, and of the Tier 2 standards for engines rated under 50 hp. This review was completed in 2001 and documented in an EPA staff technical paper that confirmed the feasibility of those standards, finding that the number of potential control options had expanded since the 1998 final rule to include new technologies and more effective application of existing technologies.\2\ --------------------------------------------------------------------------- \2\ ``Nonroad Diesel Emissions Standards Staff Technical Paper'', EPA420-R-01-052, October 2001. --------------------------------------------------------------------------- There are two basic parts to this proposed program: (1) New exhaust emission standards and test procedures for nonroad diesel engines, and (2) new sulfur limits for nonroad, locomotive, and marine diesel fuel. The systems approach of combining the engine and fuel standards into a single program is critical to the success of our overall efforts to reduce emissions, because the emission standards will not be feasible without the fuel change. This proposal is largely based on the 2007 highway diesel program. We looked at a number of alternative program options, as discussed in more detail in section VI below and chapter 12 of the draft Regulatory Impact Analysis (RIA). For example, we analyzed a program that would require refiners to produce 15 ppm nonroad diesel fuel starting in 2008, with appropriate engine standards phased-in beginning in 2009. Many of these alternatives provided a very similar level of projected emissions control and health and welfare benefits as our proposed program. However, taking into account the need for appropriate lead time, achieving the greatest possible emissions reductions as early as possible, and the interaction of requirements in this proposal with existing highway diesel engine environmental programs, we believe our proposed program provides the best opportunity for achieving all of our goals, as described above, including timely and significant emissions reductions from nonroad diesel engines and the associated introduction of ultra low sulfur nonroad diesel fuel. We are asking for comments on the alternatives discussed in this proposal. The elements of the rule are outlined below. Detailed provisions and justifications for our proposed rule are discussed in subsequent sections and the draft RIA. 1. Nonroad Diesel Engine Emission Standards Today's action proposes standards for nonroad diesel engines ranging from 3 to over 3,000 horsepower. Applicable emissions standards are determined by year for each of five engine power band categories. For engines less than 25 hp, we are proposing new engine standards for PM (0.30 g/bhp-hr) and CO (4.9 g/bhp-hr) to go along with existing NOX standards beginning in 2008. For engines between 25-75 hp, we are proposing standards reflecting approximately 50% reduction in PM control from today's engines applicable in 2008. Then, starting in 2013, PM standards of 0.02 g/bhp-hr and NOX standards of 3.5 g/bhp-hr would apply. For engines between 75-175 hp, the proposed standards would be 0.01 g/bhp-hr for PM, 0.30 g/bhp-hr for NOX, and 0.14 g/bhp-hr for HC beginning in 2012. These same standards would apply for both engines between 175-750 hp and greater than 750 hp starting in 2011. These PM, NOX, and NMHC standards are similar in stringency to the final standards included in the 2007 highway diesel program and are expected to require the use of high-efficiency aftertreatment systems to ensure compliance. Thus, virtually all nonroad diesel engines after 2013 would likely be using advanced aftertreatment systems. We are phasing in many of these proposed standards over a period of three years in order to address lead time, workload, and feasibility considerations. We are also proposing to continue the averaging, banking, and trading nonroad emissions credits provisions to demonstrate compliance with the standards. In addition, we are proposing to include turbocharged diesels in the existing prohibition on crankcase emissions, effective in the same year that the proposed Tier 4 standards first apply in each power category. More specific information on the proposed standards can be found in section III below. [[Page 28334]] To better ensure the benefits of the standards are realized in-use and throughout the useful life of these engines, we are also proposing new test procedures and related certification requirements. We believe the new supplemental transient test, Constant Speed Variable Load transient duty cycle, cold start transient test, and not-to-exceed test procedures and standards will all help achieve our goal. This is a significant and important aspect of this proposal that would bring greater confidence and certainty to the compliance program. The proposal also includes provisions to facilitate the transition to the new engine and fuel standards and to encourage the early introduction of clean technologies. We are also including proposed adjustments to various fuel and engine testing and compliance requirements. These provisions are described further in sections III, IV, and VI. 2. Nonroad, Locomotive, and Marine Diesel Fuel Quality Standards We are proposing that sulfur levels for nonroad diesel fuel be reduced from current uncontrolled levels ultimately to 15 ppm, though we are proposing an interim cap of 500 ppm. Beginning June 1, 2007, refiners would therefore be required to produce nonroad, locomotive, and marine diesel fuel that meets a maximum sulfur level of 500 ppm. This does not include diesel fuel for home heating, industrial boiler, or stationary power uses or diesel fuel used in aircraft. We estimate there are significant health and welfare benefits associated with this proposed reduction, including reductions in sulfate emissions and reduced engine operating expenses. Then, beginning in June 1, 2010, fuel used for nonroad diesel applications (excluding locomotive and marine engines) is proposed to meet a maximum sulfur level of 15 ppm, since all 2011 and later model year nonroad diesel-fueled engines with aftertreatment must be refueled with this new ultra low sulfur diesel fuel. This sulfur standard is based on our assessment of the impact of sulfur on advanced exhaust emission control technologies and a corresponding assessment of the feasibility of ultra low sulfur fuel production and distribution. We are also asking for comment on bringing sulfur levels for locomotive and marine fuel to 15 ppm in 2010 and note that we anticipate beginning the process of developing new engine controls for these two sources in 2004. This proposal includes a combination of provisions available to refiners, especially small refiners, to ensure a smooth transition to ultra low sulfur nonroad diesel fuel. In addition, this proposal includes unique provisions for implementing the ultra low sulfur diesel fuel program in the State of Alaska. We are also proposing that certain U.S. territories be excluded from both the nonroad engine standards and diesel fuel standards. Similar actions were taken as part of the 2007 highway diesel program. The compliance provisions for ensuring diesel fuel quality are essentially consistent with those that have been in effect since 1993 for highway diesel fuel, reflecting updated requirements that were included in the 2007 highway diesel program. Additional compliance provisions are proposed for the transition years of the program concerning the interaction of the nonroad, locomotive, and marine sulfur control requirements with existing highway diesel sulfur control provisions. These provisions could also help discourage misfueling of nonroad equipment utilizing high-efficiency aftertreatment devices. The proposed compliance requirements include provisions that would prohibit equipment operators from fueling their machines with higher sulfur fuels after completion of the shift to lower sulfur nonroad diesel fuels, regardless of the age of their equipment. B. Why Is EPA Making This Proposal? 1. Nonroad, Locomotive, and Marine Diesels Contribute to Serious Air Pollution Problems As discussed in detail in section II and chapter 2 and 3 of draft RIA, emissions from nonroad, locomotive, and marine diesel engines contribute greatly to a number of serious air pollution problems, and these emissions would have continued to do so into the future absent further controls to reduce them. First, these engines contribute to the health and welfare effects associated with ozone, PM, NOX, SOX, and volatile organic compounds (VOCs), including toxic compounds such as formaldehyde. These adverse effects 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 structures, altered respiratory defense mechanisms, chronic bronchitis, and decreased lung function.3 4 5 Second and importantly, in addition to its contribution to ambient PM inventories, diesel exhaust is of specific concern because it has been judged to likely pose a lung cancer hazard for humans as well as a hazard from noncancer respiratory effects. The Agency has classified diesel exhaust as likely to be carcinogenic to humans by inhalation at environmental exposures. Third, ozone and PM cause significant public welfare harm. Specifically, ozone causes damage to vegetation which leads to economic crop and forestry losses, as well as harm to national parks, wilderness areas, and other natural systems. PM causes damage to materials and soiling of commonly used building materials and culturally important items such as statues and works of art. Fourth, NOX, SOX and direct emissions of PM contribute to substantial visibility impairment in many parts of the U.S. where people live, work, and recreate, including mandatory Federal Class I areas. Finally, NOX emissions from nonroad diesel engines contribute to the acidification, nitrification and eutrophication of water bodies. --------------------------------------------------------------------------- \3\ U.S. EPA (1996) Air Quality Criteria for Particulate Matter--Volumes I, II, and III, EPA Office of Research and Development, National Center for Environmental Assessment, July 1996. Report No. EPA/600/P-95/001aF, EPA/600/P-95/001bF, EPA/600/P- 95/001cF. \4\ U.S. EPA (2002), Air Quality Criteria for Particulate Matter--Volumes I and II (Third External Review Draft). This material is available electronically at http://cfpub.epa.gov/ncea/ cfm/partmatt.cfm. \5\ U.S. EPA (1996) Air Quality Criteria for Ozone and Related Photochemical Oxidants. EPA Office of Research and Development, National Center for Environmental Assessment, July 1996. Report No. EPA/600/P-93/004aF. The document is available on the Internet at http://www.epa.gov/ncea/ozone.htm. --------------------------------------------------------------------------- Millions of Americans live in areas with unhealthful air quality that may endanger public health and welfare (i.e., levels not requisite to protect the public health with an adequate margin of safety). Based upon data for 1999-2001, there are 291 counties that are violating the 8-hour ozone NAAQS, totaling 111 million people. In addition, at least 65 million people in 129 counties live in areas where annual design values of ambient PM2.5 violate the PM2.5 NAAQS. There are an additional 9 million people in 20 counties where levels above the PM2.5 NAAQS are being measured, but the data are incomplete. Without emission reductions from the proposed new standards for nonroad engines, there is a significant future risk that 32 counties with 47 million people across the country may violate the 8- hour ozone national ambient air quality standard (NAAQS) in 2030, based on our modeling. Similarly, modeled PM2.5 concentrations in 107 counties where 85 million people live are above specified levels in 2030. An additional 64 million people are projected to live in counties [[Page 28335]] within 10 percent of the PM2.5 standard in 2030, and 44 million people are projected to live in counties within 10 percent of the level of the 8-hour standard in 2030. Thus, our analyses show that these counties face a significant risk of exceeding or failing to maintain the PM2.5 and the 8-hour ozone NAAQS without significant additional controls between 2007 and 2030. Federal, State and local governments are working to bring ozone and particulate levels into compliance with the NAAQS through State Implementation Plan (SIP) attainment and maintenance plans, and to ensure that future air quality reaches and continues to achieve these health- and welfare-based standards. The reductions in this proposed rulemaking will play a critical part in these important efforts to attain and maintain the NAAQS. In addition, reductions from this action will also reduce public health and welfare effects associated with maintenance of the 1-hour ozone and PM10 NAAQS. Emissions from nonroad, locomotive, and marine diesel engines account for substantial portions of the country's ambient PM and NOX levels. NOX is a key precursor to ozone and PM formation. We estimate that these engines account for about ten percent of total NOX emissions and about ten percent of total PM emissions. These proportions are even higher in some urban areas, where these engines contribute up to 19 percent of the total NOX emissions and up to 18 percent of the total PM emissions inventory. Over time, the relative contribution of these diesel engines to air quality problems will go even higher unless EPA takes action to further reduce pollution levels. For example, EPA has already taken steps to bring emissions levels from light-duty and heavy-duty vehicles and engines to near-zero levels by the end of this decade. The PM and NOX standards for nonroad, locomotive, and marine diesel engines in this proposal would have a substantial impact on emissions. By 2030, NOX emissions from these diesel engines under today's standards will be reduced by 827,000 tons, and PM emissions will decline by about 127,000 tons, dramatically reducing this source of NOX and PM emissions. Urban areas, which include many poorer neighborhoods, can be disproportionately impacted by such diesel emissions, and these neighborhoods will thus receive a relatively larger portion of the benefits expected from proposed emissions controls. Diesel exhaust is of special concern because it is associated with increased risk of lung cancer and respiratory disease. EPA recently issued its Health Assessment Document for Diesel Exhaust.\6\ The Agency has classified diesel exhaust as likely to be carcinogenic to humans by inhalation at environmental exposures. State and local governments, in their efforts to protect the health of their citizens and comply with requirements of the Clean Air Act (CAA or ``the Act''), have recognized the need to achieve major reductions in diesel PM emissions, and have been seeking Agency action in setting stringent new standards to bring this about.\7\ --------------------------------------------------------------------------- \6\ U.S. EPA (2002) Health Assessment Document for Diesel Engine Exhaust. EPA/600/8-90/057F Office of Research and Development, Washington DC. This document is available electronically at http:// cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=29060. \7\ For example, see letters dated April 9, 2002, from Agency Secretary of California EPA, Commissioner of NY State DEC, and Commissioner of Texas NRCC to Governor Whitman; dated January 28, 2003 from Western Regional Air Partnership to Governor Whitman, and dated December 17, 2002, from State and Territorial Air Pollution Program Administrators and Association of Local Air Pollution Control Officials and Northeast States for Coordinated Air Use Mangement (and other organizations). --------------------------------------------------------------------------- 2. Technology and Fuel Based Solutions Although the air pollution from nonroad diesel exhaust is challenging, we believe they can be addressed through the application of high-efficiency emissions control technologies. As discussed in much greater detail in section III, the development of diesel emissions control technology has advanced in recent years so that very large emission reductions (in excess of 90 percent) are possible, especially through the use of catalytic emission control devices installed in the nonroad equipment's exhaust system and integrated with the engine controls. These devices are often referred to as ``exhaust emission control'' or ``aftertreatment'' devices. Exhaust emission control devices, in the form of the well-known catalytic converter, have been used in gasoline-fueled automobiles for 28 years. Based on the Clean Air Act requirements in section 213, we are proposing stringent new emission standards that will result in the use of these diesel exhaust emission control devices. We are also proposing changes to nonroad diesel fuel quality standards, under section 211(c) of the Act, in order to enable these high-efficiency technologies. To meet the proposed new standards, application of high-efficiency exhaust emission controls for both PM and NOX will be needed for most engines. High-efficiency PM exhaust emission control technology has been available for several years. This technology has continued to improve over the years, especially with respect to durability and robust operation in use. It has also proved extremely effective in reducing exhaust hydrocarbon emissions. Thousands of such systems are now in use, especially in Europe. It is the same technology we expect to be applied to meet the PM standards in the 2007 heavy-duty highway diesel engine rule. However, as discussed in detail in section III, these systems are very sensitive to sulfur in the fuel. For the technology to be viable and capable of meeting the standards, we believe it will require diesel fuel with sulfur content capped at the 15 ppm level. Similarly, high-efficiency NOX exhaust emission control technology will be needed if nonroad diesel engines are to attain the proposed standards. This is the same technology that we anticipate will be applied to heavy-duty highway diesel engines to meet the NOX standards included in the 2007 highway diesel program. This technology, like the PM technology, is dependant on the 15 ppm maximum nonroad diesel fuel levels being proposed in this action in order to be feasible and capable of achieving the standards. Similar high-efficiency NOX exhaust emission control technology has been quite successful in gasoline direct injection engines that operate with an exhaust composition fairly similar to diesel exhaust and is expected to be used to meet the 2007 and later heavy-duty highway diesel standards. As discussed in section III, application of this technology to nonroad diesels has some additional engineering challenges. In that section, we discuss the current status of this technology as well as the major development issues still to be addressed and the development steps that can be taken. With the lead- time available and the introduction of ultra low sulfur nonroad diesel fuel, we are confident the proposed application of this technology to nonroad diesels would proceed at a reasonable rate of progress and will result in systems capable of achieving the standards. This view is further supported by the fact that manufacturers are already working on developing high-efficiency aftertreatment devices in order to have them available for introduction on highway diesel engines by 2007. EPA issued a progress report in June 2002 which discussed our findings that industry was making substantial progress in developing these devices. Additionally, the Clean Diesel Independent Review Panel issued a report in October 2002 on similar [[Page 28336]] questions and concluded that, while technical issues remain, there were no technical hurdles identified that would prevent market introduction of high-efficiency aftertreatment devices on schedule. The need to reduce sulfur in nonroad diesel fuel is driven by the requirements of the exhaust emission control technology that we project will be needed to meet the proposed standards for most nonroad diesel engines. The challenge in accomplishing the sulfur reduction is driven by the capacity to implement the needed refinery modifications, and by the costs of making the modifications and running the equipment. Today, a number of refiners are acting to provide low sulfur diesel to some markets. We believe that controlling the sulfur content of highway diesel fuel to the 15 ppm level is necessary, feasible, and cost- effective. Additionally, there are health and welfare benefits associated with the initial step of reducing the sulfur level of nonroad, locomotive, and marine diesel fuel to 500 ppm. This proposed action will provide dramatic, immediate reductions in direct sulfate PM and SO2 emissions from the in-use fleet. As described in this proposal, we believe this fuel control strategy is a cost-effective air quality solution as well. 3. Basis for Action Under the Clean Air Act Section 213 of the Act gives us the authority to establish emissions standards for nonroad engines and vehicles. Section 213(a)(3) authorizes the Administrator to set standards for NOX, VOCs, or carbon monoxide, to reduce ambient levels of ozone and carbon monoxide which ``standards shall achieve the greatest degree of emission reduction achievable through the application of technology which the Administrator determines will be available for the engines or vehicles.'' As part of this determination, the Administrator must give appropriate consideration to cost, lead time, noise, energy, and safety factors associated with the application of such technology. Section 213(a)(4) authorizes the Administrator to establish standards to control emissions of pollutants which ``may reasonably be anticipated to endanger public health and welfare''. Here, the Administrator may promulgate regulations that are deemed appropriate for new nonroad vehicles and engines which cause or contribute to such air pollution, taking into account costs, noise, safety, and energy factors. EPA believes the proposed controls for PM in today's rule would be an appropriate exercise of EPA's discretion under the authority of section 213(a)(4). We believe the evidence provided in section III and the Draft Regulatory Impact Analysis (RIA) indicates that the stringent emission standards proposed today are feasible and reflect the greatest degree of emission reduction achievable in the model years to which they apply. We have given appropriate consideration to costs in proposing these standards. Our review of the costs and cost-effectiveness of these standards indicate that they will be reasonable and comparable to the cost-effectiveness of other emission reduction strategies that have been required or could be required in the future. We have also reviewed and given appropriate consideration to the energy factors of this rule in terms of fuel efficiency and effects on diesel fuel supply, production, and distribution, as discussed below, as well as any safety factors associated with these proposed standards. The information in section II and chapter 2 of the draft RIA regarding air quality and the contribution of nonroad, locomotive, and marine diesel engines to air pollution provides strong evidence that emissions from such engines significantly and adversely impact public health or welfare. First, as noted earlier, there is a significant risk that several areas will fail to attain or maintain compliance with the NAAQS for 8-hour ozone concentrations or for PM2.5 concentrations during the period that these new vehicle and engine standards will be phased into the vehicle population, and that nonroad, locomotive, and marine diesel engines contribute to such concentrations, as well as to concentrations of other NAAQS-related pollutants. This risk will be significantly reduced by the standards adopted today, as also noted above. However, the evidence indicates that some risk remains even after the reductions achieved by these new controls on nonroad diesel engines and nonroad, locomotive, and marine diesel fuel. Second, EPA believes that diesel exhaust is likely to be carcinogenic to humans. The risk associated with exposure to diesel exhaust includes the particulate and gaseous components among which are benzene, formaldehyde, acetaldehyde, acrolein, and 1,3-butadiene, all of which are known or suspected human or animal carcinogens, or have serious noncancer health effects. Third, emissions from nonroad diesel engines (including locomotive and marine diesel engines) contribute to regional haze and impaired visibility across the nation, as well as acid deposition, POM deposition, eutrophication and nitrification, all of which are serious environmental welfare problems. EPA has already found in previous rules that emissions from new nonroad diesel engines contribute to ozone and carbon monoxide (CO) concentrations in more than one area which has failed to attain the ozone and carbon monoxide NAAQS. 59 FR 31306 (June 17, 1994). EPA has also previously determined that it is appropriate to establish standards for PM from new nonroad diesel engines under section 213(a)(4), and the additional information on diesel exhaust carcinogenicity noted above reinforces this finding. In addition, we have already found that emissions from nonroad engines significantly contribute to air pollution that may reasonably be anticipated to endanger public welfare due to regional haze and visibility impairment. 67 FR 68242, 68243 (Nov. 8, 2002). We find here, based on the information in section II of this preamble and chapter 2 of the draft RIA, that emissions from the new nonroad diesel engines covered by this proposal likewise contribute to regional haze and to visibility impairment that may reasonably be anticipated to endanger public welfare. Taken together, these findings indicate the appropriateness of the nonroad diesel engine standards proposed today for purposes of section 213(a)(3) and (4) of the Act. Section 211(c) of the CAA allows us to regulate fuels where emission products of the fuel either: (1) Cause or contribute to air pollution that reasonably may be anticipated to endanger public health or welfare, or (2) will impair to a significant degree the performance of any emission control device or system which is in general use, or which the Administrator finds has been developed to a point where in a reasonable time it will be in general use were such a regulation to be promulgated. This rule meets both of these criteria. SOx and sulfate PM emissions from nonroad, locomotive, marine and diesel vehicles are due to sulfur in diesel fuel. As discussed above, emissions of these pollutants cause or contribute to ambient levels of air pollution that endanger public health and welfare. Control of sulfur to 500 ppm for this fuel would lead to significant, cost-effective reductions in emissions of these pollutants. The substantial adverse effect of high sulfur levels on the performance of diesel emission control devices or systems that would be expected to be used to meet the nonroad standards is discussed in detail in section III. Control of sulfur to 15 ppm in nonroad diesel fuel would enable emissions control technology that will achieve significant, cost- [[Page 28337]] effective reduction in emissions of these pollutants, as discussed in section II below. In addition, our authority under section 211(c) is discussed in more detail in Appendix A to the draft RIA. II. What Is the Air Quality Impact of the Sources Covered by the Proposed Rule? With this proposal, EPA is acting to extend highway types of emission controls to another major source of diesel engine emissions, nonroad diesel engines. These emissions are significant contributors to atmospheric pollution from particulate matter, ozone and a variety of toxic air pollutants. In our most recent nationwide inventory used for this proposal (1996), the nonroad diesels affected by this proposal \8\ contribute over 43 percent of diesel PM emissions from mobile sources, up to 18 percent of PM2.5 emissions in urban areas, and up to 14 percent of NOX emissions in urban areas. --------------------------------------------------------------------------- \8\ For NOX and PM2.5 this includes all land-based nonroad diesel engines, but not locomotive, commercial marine vessel, and recreational marine vessel engines. Since the latter three engine categories are affected by the fuel sulfur portions of the proposal, they are included for SO2. --------------------------------------------------------------------------- Without further control beyond those standards we have already adopted, by the year 2020, these engines will emit 62 percent of diesel PM emissions from mobile sources, up to 19 percent of PM2.5 emissions in urban areas, and up to 20 percent of NOX emissions in urban areas. When fully implemented, this proposal would reduce nonroad diesel PM2.5 and NOX emissions by more than 90 percent. It will also virtually eliminate nonroad diesel SOx emissions, which amounted to nearly 230,000 tons in 1996, and would otherwise grow to approximately 340,000 tons by 2020. These dramatic reductions in nonroad emissions are a critical part of the effort by Federal, State and local governments to reduce the health-related impacts of air pollution and to reach attainment of the NAAQS for PM and ozone, as well as to improve other environmental effects such as atmospheric visibility. Based on the most recent data available for this rule (1999-2001), such problems are widespread in the United States. There are over 65 million people living in counties with monitored PM2.5 levels exceeding the PM2.5 NAAQS, and 111 million people living in counties with monitored concentrations exceeding the 8-hour ozone NAAQS. Figure II.-1 illustrates the widespread nature of these problems. Shown in this figure are counties exceeding either or both of the two NAAQS plus mandatory Federal Class I areas, which have particular needs for reductions in atmospheric haze. [GRAPHIC] [TIFF OMITTED] TP23MY03.000 As we will describe later in this preamble, the air quality improvements expected from this proposal is anticipated to produce major benefits to human health and welfare, with a combined value in excess of half a [[Page 28338]] trillion dollars between 2007 and 2030. By the year 2030, this proposed rule would be expected to prevent approximately 9,600 deaths per year from premature mortality, and 16,000 nonfatal heart attacks. It is estimated to also prevent 14,000 acute bronchitis attacks in children, 260,000 respiratory symptoms in children, and nearly 1 million lost work days in 2030. The reductions will also improve visibility. In the remainder of this section we will describe in more detail the air pollution problems associated with emissions from nonroad diesel engines, and the emission and air quality benefits we expect to realize from the fuel and engine controls in this proposal. A. Overview The emissions from nonroad engines that are being directly controlled by the standards in this rulemaking are NOX, PM and NMHC, and to a lesser extent, CO. Gaseous air toxics from nonroad diesels will also be reduced as a consequence of the proposed standards. In addition there will be a substantial reduction in SOx emissions resulting from the proposed reduction in sulfur level in diesel fuel. From a public health perspective, we are primarily concerned with nonroad engine contributions to atmospheric levels of particulate matter in general, diesel PM in particular and various gaseous air toxics emitted by diesel engines, and ozone.\9\ We will first review important public health effects linked to these pollutants, briefly describing the human health effects and the current and expected future ambient levels of direct or indirectly caused pollution. Our presentation will show that substantial further reductions of these pollutants, and the underlying emissions from nonroad diesel engines, are needed to protect public health. --------------------------------------------------------------------------- \9\ Ambient particulate matter from nonroad diesel engine is associated with the direct emission of diesel particulate matter, and with particulate matter formed indirectly in the atmosphere by NOX and SOx emissions (and to a lesser extent NMHC emissions). Both NOX and NMHC participate in the atmospheric chemical reactions that produce ozone. --------------------------------------------------------------------------- Following discussion of health effects, we will discuss a number of welfare effects associated with emissions from diesel engines. These effects include atmospheric visibility impairment, ecological and property damage caused by acid deposition, eutrophication and nitrification of surface waters, environmental threats posed by polycyclic organic matter (POM) deposition, and plant and crop damage from ozone. Once again, the information available to us indicates a continuing need for further nonroad emission reductions to bring about improvements in air quality. Next, we will describe our understanding of the engine emission inventories for the primary pollutants affected by the proposal. As noted above, these include PM, NOX, SOX, Air Toxics and HC. We will present current and projected future levels of emissions for the base case, including anticipated reductions from control programs already adopted by EPA and the States, but without the controls proposed today. Then we will identify expected emission reductions from nonroad engines. These reductions will make important contributions to controlling the health and welfare problems associated with ambient PM and ozone levels and with diesel related air toxics. While the material we will present in this section will describe our understanding of the need for control of nonroad engine emissions and the air quality improvements we expect to realize, this section is not an exhaustive treatment of these issues. For a fuller understanding of the topics treated here, you should refer to the extended presentations in the Draft Regulatory Impact Analysis accompanying this proposal. B. Public Health Impacts 1. Particulate Matter Particulate matter (PM) represents a broad class of chemically and physically diverse substances. It can be principally characterized as discrete particles that exist in the condensed (liquid or solid) phase spanning several orders of magnitude in size. PM10 refers to particles with an aerodynamic diameter less than or equal to a nominal 10 micrometers. Fine particles refer to those particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers (also known as PM2.5), and coarse fraction particles are those particles with an aerodynamic diameter greater than 2.5 microns, but less than or equal to a nominal 10 micrometers. Ultrafine PM refers to particles with diameters of less than 100 nanometers (0.1 micrometers). The health and environmental effects of PM are associated with fine PM fraction and, in some cases, to the size of the particles. Specifically, larger particles (10 [mu]m) tend to be removed by the respiratory clearance mechanisms whereas smaller particles are deposited deeper in the lungs. Also, particles scatter light obstructing visibility. The emission sources, formation processes, chemical composition, atmospheric residence times, transport distances and other parameters of fine and coarse particles are distinct. Fine particles are directly emitted from combustion sources and are formed secondarily from gaseous precursors such as sulfur dioxide (SOX), oxides of nitrogen (NOX), or organic compounds. Fine particles are generally composed of sulfate, nitrate, chloride, ammonium compounds, organic carbon, elemental carbon, and metals. Nonroad diesels currently emit high levels of NOX which react in the atmosphere to form secondary PM2.5 (namely ammonium nitrate). Nonroad diesel engines also emit SO2 and HC which react in the atmosphere to form secondary PM2.5 (namely sulfates and organic carbonaceous PM2.5). Combustion of coal, oil, diesel, gasoline, and wood, as well as high temperature process sources such as smelters and steel mills, produce emissions that contribute to fine particle formation. In contrast, coarse particles are typically mechanically generated by crushing or grinding. They include resuspended dusts and crustal material from paved roads, unpaved roads, construction, farming, and mining activities. These coarse particles can be either natural in source such as road dust or anthropogenic. Fine particles can remain in the atmosphere for days to weeks and travel through the atmosphere hundreds to thousands of kilometers, while coarse particles deposit to the earth within minutes to hours and within tens of kilometers from the emission source. The relative contribution of various chemical components to PM2.5 varies by region of the country. Data on PM2.5 composition are available from the EPA Speciation Trends Network in 2001 and the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network in 1999 covering both urban and rural areas in numerous regions of the U.S. These data show that carbonaceous PM2.5 makes up the major component for PM2.5 in both urban and rural areas in the western U.S. Carbonaceous PM2.5 includes both elemental and organic carbon. Nitrates formed from NOX also play a major role in the western U.S., especially in the California area where it is responsible for about a quarter of the ambient PM2.5 concentrations. Sulfate plays a lesser role in these regions. For the eastern and mid U.S., these data show that both sulfates and carbonaceous PM2.5 are major contributors to ambient PM2.5 in both urban and rural areas. In some eastern areas, carbonaceous PM2.5 is responsible for up to half of ambient PM2.5 concentrations. Sulfate is also a [[Page 28339]] major contributor to ambient PM2.5 in the eastern U.S. and in some areas make greater contributions than carbonaceous PM2.510 11 --------------------------------------------------------------------------- \10\ Rao, Venkatesh; Frank, N.; Rush, A.; and Dimmick, F. (November 13-15, 2002). Chemical speciation of PM2.5 in urban and rural areas (November 13-15, 2002) In the Proceedings of the Air & Waste Management Association Symposium on Air Quality Measurement Methods and Technology, San Francisco Meeting. \11\ EPA (2002) Latest Finds on National Air Quality, EPA 454/K- 02-001. --------------------------------------------------------------------------- Nonroad engines, and most importantly nonroad diesel engines, contribute significantly to ambient PM2.5 levels, largely through emissions of carbonaceous PM2.5. Carbonaceous PM2.5 is a major portion of ambient PM2.5, especially in populous urban areas. Nonroad diesels also emit high levels of NOX which react in the atmosphere to form secondary PM2.5 (namely nitrate). Nonroad diesels also emit SO2 and NMHC which react in the atmosphere to form secondary PM2.5 (namely sulfates and organic carbonaceous PM2.5). For more details, consult the draft RIA for this proposed rule. Diesel particles from nonroad diesel are a component of both coarse and fine PM, but fall mainly in the fine (and even ultrafine) size range. As discussed later, diesel PM also contains small quantities of numerous mutagenic and carcinogenic compounds associated with the particulate (and also organic gases). In addition, while toxic trace metals emitted by nonroad diesel engines represent a very small portion of the national emissions of metals (less than one percent) and a small portion of diesel PM (generally less than one percent of diesel PM), we note that several trace metals of potential toxicological significance and persistence in the environment are emitted by diesel engines. These trace metals include chromium, manganese, mercury and nickel. In addition, small amounts of dioxins have been measured in highway engine diesel exhaust, some of which may partition into the particulate phase; dioxins through out the environment are a major health concern (although the diesel contribution has not been judged significant at this point). Diesel engines also emit polycyclic organic matter (POM), including polycyclic aromatic hydrocarbons (PAH), which can be present in both gas and particle phases of diesel exhaust. Many PAH compounds are classified by EPA as probable human carcinogens. For additional, detailed, information on PM beyond that summarized below, see the draft Regulatory Impact Analysis. a. Health Effects of PM2.5 and PM10 Scientific studies show ambient PM (which is attributable to a number of sources, including nonroad diesel) is associated with a series of adverse health effects. These health effects are discussed in detail in the EPA Criteria Document for PM as well as the draft updates of this document released in the past year.12 13 In addition, EPA's final ``Health Assessment Document for Diesel Engine Exhaust,'' (the Diesel HAD) also reviews health effects information related to diesel exhaust as a whole including diesel PM, which is one component of ambient PM.\14\ --------------------------------------------------------------------------- \12\ U.S. EPA (1996.) Air Quality Criteria for Particulate Matter--Volumes I, II, and III, EPA, Office of Research and Development. Report No. EPA/600/P-95/001a-cF. This material is available electronically at http://www.epa.gov/ttn/oarpg/ticd.html. \13\ U.S. EPA (2002). Air Quality Criteria for Particulate Matter--Volumes I and II (Third External Review Draft) This material is available electronically at http://cfpub.epa.gov/ncea/cfm/ partmatt.cfm. \14\ U.S. EPA (2002). Health Assessment Document for Diesel Engine Exhaust. EPA/600/8-90/057F Office of Research and Development, Washington DC. This document is available electronically at http://cfpub.epa.gov/ncea/cfm/ recordisplay.cfm?deid=29060. --------------------------------------------------------------------------- As described in these documents, health effects associated with short-term variation in ambient particulate matter (PM) have been indicated by epidemiologic studies showing associations between exposure and increased hospital admissions for ischemic heart disease, heart failure, respiratory disease, including chronic obstructive pulmonary disease (COPD) and pneumonia. Short-term elevations in ambient PM have also been associated with increased cough, lower respiratory symptoms, and decrements in lung function. Short-term variations in ambient PM have also been associated with increases in total and cardiorespiratory daily mortality. Studies examining populations exposed to different levels of air pollution over a number of years, including the Harvard Six Cities Study and the American Cancer Society Study suggest an association between exposure to ambient PM2.5 and premature mortality, including deaths attributed to lung cancer.15 16 Two studies further analyzing the Harvard Six Cities Study's air quality data have also established a specific influence of mobile source-related PM2.5 on daily mortality \17\ and a concentration-response function for mobile source- associated PM2.5 and daily mortality.\18\ Another recent study in 14 U.S. cities examining the effect of PM10 on daily hospital admissions for cardiovascular disease found that the effect of PM10 was significantly greater in areas with a larger proportion of PM10 coming from motor vehicles, indicating that PM10 from these sources may have a greater effect on the toxicity of ambient PM10 when compared with other sources.\19\ Additional studies have associated changes in heart rate and/or heart rhythm in addition to changes in blood characteristics with exposure to ambient PM.20 21 For additional information on health effects, see the draft RIA. --------------------------------------------------------------------------- \15\ Dockery, DW; Pope, CA, III; Xu, X; et al. (1993) An association between air pollution and mortality in six U.S. cities. N Engl J Med 329:1753-1759. \16\ Pope, CA, III; Thun, MJ; Namboordiri, MM; et al. (1995) Particulate air pollution as a predictor of mortality in a prospective study of U.S. adults. Am J Respir Crit Care Med 151:669- 674. \17\ Laden F; Neas LM; Dockery DW; et al. (2000) Association of fine particulate matter from different sources with daily mortality in six U.S. cities. Environ Health Perspect 108(10):941-947. \18\ Schwartz J; Laden F; Zanobetti A. (2002) The concentration- response relation between PM(2.5) and daily deaths. Environ Health Perspect 110(10): 1025-1029. \19\ Janssen NA; Schwartz J; Zanobetti A.; et al. (2002) Air conditioning and source-specific particles as modifiers of the effect of PM10 on hospital admissions for heart and lung disease. Environ Health Perspect 110(1):43-49. \20\ Pope CA III, Verrier RL, Lovett EG; et al. (1999) Heart rate variability associated with particulate air pollution. Am Heart J 138(5 Pt 1):890-899. \21\ Magari SR, Hauser R, Schwartz J; et al. (2001) Association of heart rate variability with occupational and environmental exposure to particulate air pollution. Circulation 104(9):986-991. --------------------------------------------------------------------------- The health effects of PM10 are similar to those of PM2.5, since PM10 includes all of PM2.5 plus the coarse fraction from 2.5 to 10 micrometers in size. EPA is also evaluating the health effects of PM between 2.5 and 10 micrometers in the draft revised Criteria Document. As discussed in the Diesel HAD and other studies, most diesel PM is smaller than 2.5 micrometers.\22\ Both fine and coarse fraction particles can enter and deposit in the respiratory system. --------------------------------------------------------------------------- \22\ U.S. EPA (1985). Size specific total particulate emission factor for mobile sources. EPA 460/3-85-005. Office of Mobile Sources, Ann Arbor, MI. --------------------------------------------------------------------------- In addition to the information in the draft revised Criteria Document, the relevance of health effects associated with on-road diesel engine-generated PM to nonroad applications is supported by the observation in the Diesel HAD that the particulate characteristics in the zone around nonroad diesel engines is likely to be substantially the same as published air quality measurements made along busy roadways. Of particular relevance to this rule is a recent cohort study which examined the association between mortality and [[Page 28340]] residential proximity to major roads in the Netherlands. Examining a cohort of 55 to 69 year-olds from 1986 to1994, the study indicated that long-term residence near major roads, an index of exposure to primary mobile source emissions (including diesel exhaust), was significantly associated with increased cardiopulmonary mortality.\23\ Other studies have shown children living near roads with high truck traffic density have decreased lung function and greater prevalence of lower respiratory symptoms compared to children living on other roads.\24\ A recent review of epidemiologic studies examining associations between asthma and roadway proximity concluded that some coherence was evident in the literature, indicating that asthma, lung function decrement, respiratory symptoms, and other respiratory problems appear to occur more frequently in people living near busy roads.\25\ As discussed later, nonroad diesel engine emissions, especially particulate, are similar in composition to those from highway diesel vehicles. Although difficult to associate directly with PM2.5, these studies indicate that direct emissions from mobile sources, and diesel engines specifically, may explain a portion of respiratory health effects observed in larger-scale epidemiologic studies. Recent studies conducted in Los Angeles have illustrated that a substantial increase in the concentration of ultrafine particles is evident in locations near roadways, indicating substantial differences in the nature of PM immediately near mobile source emissions.\26\ --------------------------------------------------------------------------- \23\ Hoek, G; Brunekreef, B; Goldbohm, S; et al. (2002) Association between mortality and indicators of traffic-related air pollution in the Netherlands: a cohort study. Lancet 360(9341): 1203-1209. \24\ Brunekreef, B; Janssen NA; de Hartog, J; et al. (1997) Air pollution from traffic and lung function in children living near motor ways. Epidemiology (8): 298-303. \25\ Delfino RJ. (2002) Epidemiologic evidence for asthma and exposure to air toxics: linkages between occupational, indoor, and community air pollution research. Env Health Perspect Suppl 110(4): 573-589. \26\ Yifang Zhu, William C. Hinds, Seongheon Kim, Si Shen and Constantinos Sioutas Zhu Y; Hinds WC; Kim S; et al. (2002) Study of ultrafine particles near a major highway with heavy-duty diesel traffic. Atmos Environ 36(27): 4323-4335. --------------------------------------------------------------------------- Also, as discussed in more detail later, in addition to its contribution to ambient PM inventories, diesel PM is of special concern because diesel exhaust has been associated with an increased risk of lung cancer. As also discussed later in more detail, we concluded that diesel exhaust ranks with other substances that the national-scale air toxics assessment suggests pose the greatest relative risk. b. Current and Projected Levels There are NAAQS for both PM10 and PM2.5. Violations of the annual PM2.5 standard are much more widespread than are violations of the PM10 standards. Emission reductions needed to attain the PM2.5 standards will also assist in attaining and maintaining compliance with the PM10 standards. Thus, since most PM emitted by diesel nonroad engines is fine PM, the emission controls proposed today should contribute to attainment and maintenance of the existing PM NAAQS. More broadly, the proposed standards will benefit public health and welfare through reductions in direct diesel PM and reductions of NOX, SOX, and NMHCs which contribute to secondary formation of PM. The reductions from these proposed rules will assist States as they implement local controls as needed to help their areas attain and maintain the standards. i. PM10 Levels The current NAAQS for PM10 were established in 1987. The primary (health-based) and secondary (public welfare based) standards for PM10 include both short- and long-term NAAQS. The short- term (24 hour) standard of 150 ug/m3 is not to be exceeded more than once per year on average over three years. The long-term standard specifies an expected annual arithmetic mean not to exceed 50 ug/m3 averaged over three years. Currently, 29 million people live in PM10 nonattainment areas. There are currently 58 moderate PM10 nonattainment areas with a total population of 6.8 million. The attainment date for the initial moderate PM10 nonattainment areas, designated by operation of law on November 15, 1990, was December 31, 1994. Several additional PM10 nonattainment areas were designated on January 21, 1994, and the attainment date for these areas was December 31, 2000. There are an additional 8 serious PM10 nonattainment areas with a total affected population of 22.7 million. According to the Act, serious PM10 nonattainment areas must attain the standards no later than 10 years after designation. The initial serious PM10 nonattainment areas were designated January 18, 1994, and had an attainment date set by the Act of December 31, 2001. The Act provides that EPA may grant extensions of the serious area attainment dates of up to 5 years, provided that the area requesting the extension meets the requirements of section 188(e) of the Act. Four serious PM10 nonattainment areas (Phoenix, Arizona; Coachella Valley, South Coast (Los Angeles), and Owens Valley, California) have received extensions of the December 31, 2001, attainment date and thus have new attainment dates of December 31, 2006.\27\ While all of these areas are expected to be in attainment before the emission reductions from this proposed rule are expected to occur, these reductions will be important to assist these areas in maintaining the standards. --------------------------------------------------------------------------- \27\ EPA has also proposed to grant Las Vegas, Nevada, an extension until December 31, 2006. --------------------------------------------------------------------------- ii. PM2.5 Levels The need for reductions in the levels of PM2.5 is widespread. Figure II-1 at the beginning of this air quality section highlighted monitor locations measuring concentrations above the level of the NAAQS. As can be seen from that figure, high ambient levels are widespread throughout the country. The NAAQS for PM2.5 were established by EPA in 1997 (62 FR 38651, July 18, 1997). The short term (24-hour) standard is set at a level of 65 [mu]g/m3 based on the 98th percentile concentration averaged over three years. (This air quality statistic compared to the standard is referred to as the ``design value.'') The long-term standard specifies an expected annual arithmetic mean not to exceed 15 ug/m3 averaged over three years. Current PM2.5 monitored values for 1999-2001, which cover counties having about 75 percent of the country's population, indicate that at least 65 million people in 129 counties live in areas where annual design values of ambient fine PM violate the PM2.5 NAAQS. There are an additional 9 million people in 20 counties where levels above the NAAQS are being measured, but there are insufficient data at this time to calculate a design value in accordance with the standard, and thus determine whether these areas are violating the PM2.5 NAAQS. In total, this represents 37 percent of the counties and 64 percent of the population in the areas with monitors with levels above the NAAQS. Furthermore, an additional 14 million people live in 41 counties that have air quality measurements within 10 percent of the level of the standard. These areas, although not currently violating the standard, will also benefit from the additional reductions from this rule in order to ensure long term maintenance. Our air quality modeling performed for this proposal also indicates that similar conditions are likely to continue [[Page 28341]] to exist in the future in the absence of additional controls. For example, in 2020 based on emission controls currently adopted, we project that 66 million people will live in 79 counties with average PM2.5 levels above 15 ug/m\3\. In 2030, the number of people projected to live in areas exceeding the PM2.5 standard is expected to increase to 85 million in 107 counties. An additional 24 million people are projected to live in counties within 10 percent of the standard in 2020, which will increase to 64 million people in 2030. Our modeling also indicates that the reductions we are expecting will make a substantial contribution to reducing exposures in these areas.\28\ In 2020, the number of people living in counties with PM2.5 levels above the NAAQS would be reduced from 66 million to 60 million living in 67 counties, which reflects a reduction of 9 percent in potentially exposed population and 15 percent of the number of counties. In 2030, there would be a reduction from 85 million people to 71 million living in 84 counties. These represent even greater improvements than projected for 2020 (numbers of people potentially exposed down 16 percent and number of counties down 21 percent). Furthermore, our modeling also shows that the emission reductions would assist areas with future maintenance of the standards. --------------------------------------------------------------------------- \28\ The results illustrate the type of PM changes for the preliminary control option, as discussed in the Draft RIA in section 3.6. The proposal differs from the modeled control case based on updated information; however, we believe that the net results would approximate future emissions, although we anticipate the PM reductions might be slightly smaller. --------------------------------------------------------------------------- We estimate that the reduction of PM levels expected from this proposed rule would produce nationwide air quality improvements in PM levels. On a population weighted basis, the average change in future year annual averages would be a decrease of 0.33 ug/m\3\ in 2020, and 0.46 ug/m\3\ in 2030. The reductions are discussed in more detail in chapter 2 of the draft RIA. While the final implementation process for bringing the nation's air into attainment with the PM2.5 NAAQS is still being completed in a separate rulemaking action, the basic framework is well defined by the statute. EPA's current plans call for designating PM2.5 nonattainment areas in late-2004. Following designation, Section 172(b) of the Clean Air Act allows states up to three years to submit a revision to their state implementation plan (SIP) that provides for the attainment of the PM2.5 standard. Based on this provision, states could submit these SIPs as late as the end of 2007. Section 172(a)(2) of the Clean Air Act requires that these SIP revisions demonstrate that the nonattainment areas will attain the PM2.5 standard as expeditiously as practicable but no later than five years from the date that the area was designated nonattainment. However, based on the severity of the air quality problem and the availability and feasibility of control measures, the Administrator may extend the attainment date ``for a period of no greater than 10 years from the date of designation as nonattainment.'' Therefore, based on this information, we expect that most or all areas will need to attain the PM2.5 NAAQS in the 2009 to 2014 time frame, and then be required to maintain the NAAQS thereafter. Since the emission reductions expected from this proposal would begin in this same time frame, the projected reductions in nonroad emissions would be used by states in meeting the PM2.5 NAAQS. States and state organizations have told EPA that they need nonroad diesel engine reductions in order to be able to meet and maintain the PM2.5 NAAQS as well as visibility regulations, especially in light of the otherwise increasing emissions from nonroad sources without more stringent standards.29 30 31 Furthermore, this action would ensure that nonroad diesel emissions will continue to decrease as the fleet turns over in the years beyond 2014; these reductions will be important for maintenance of the NAAQS following attainment. The future reductions are also important to achieve visibility goals, as discussed later. --------------------------------------------------------------------------- \29\ California Air Resources Board and New York State Department of Environmental Conservation (April 9, 2002), Letter to EPA Administrator Christine Todd Whitman. \30\ State and Territorial Air Pollution Program Administrators (STAPPA) and Association of Local Air Pollution Control Officials (ALAPCO) (December 17, 2002), Letter to EPA Assistant Administrator Jeffrey R. Holmstead. \31\ Western Regional Air Partnership (WRAP) (January 28, 2003), Letter to Governor Christine Todd Whitman. --------------------------------------------------------------------------- 2. Air Toxics a. Diesel Exhaust A number of health studies have been conducted regarding diesel exhaust including epidemiologic studies of lung cancer in groups of workers, and animal studies focusing on non-cancer effects specific to diesel exhaust. Diesel exhaust PM (including the associated organic compounds which are generally high molecular weight hydrocarbon types but not the more volatile gaseous hydrocarbon compounds) is generally used as a surrogate measure for diesel exhaust. i. Potential Cancer Effects of Diesel Exhaust In addition to its contribution to ambient PM inventories, diesel exhaust is of specific concern because it has been judged to pose a lung cancer hazard for humans as well as a hazard from noncancer respiratory effects. EPA recently released its ``Health Assessment Document for Diesel Engine Exhaust,'' (the Diesel HAD).\32\ There, diesel exhaust was classified as likely to be carcinogenic to humans by inhalation at environmental exposures, in accordance with the revised draft 1996/1999 EPA cancer guidelines. A number of other agencies (National Institute for Occupational Safety and Health, the International Agency for Research on Cancer, the World Health Organization, California EPA, and the U.S. Department of Health and Human Services) have made similar classifications. It should be noted that the conclusions in the Diesel HAD were based on diesel engines currently in use, including nonroad diesel engines such as those found in bulldozers, graders, excavators, farm tractor drivers and heavy construction equipment. As new diesel engines with significantly cleaner exhaust emissions replace existing engines, the conclusions of the Diesel HAD will need to be reevaluated. --------------------------------------------------------------------------- \32\ U.S. EPA (2002). Health Assessment Document for Diesel Engine Exhaust. EPA/600/8-90/057F Office of Research and Development, Washington DC. This document is available electronically at http://cfpub.epa.gov/ncea/cfm/ recordisplay.cfm?deid=29060. --------------------------------------------------------------------------- For the EPA Diesel HAD, EPA reviewed 22 epidemiologic studies in detail, finding increased lung cancer risk in 8 out of 10 cohort studies and 10 out of 12 case-control studies. Relative risk for lung cancer associated with exposure range from 1.2 to 2.6. In addition, two meta-analyses of occupational studies of diesel exhaust and lung cancer have estimated the smoking-adjusted relative risk of 1.35 and 1.47, examining 23 and 30 studies, respectively.33 34 That is, these two studies show an overall increase in lung cancer for the exposed groups of 35 percent and 47 percent compared to the groups not exposed to diesel exhaust. In the EPA Diesel HAD, EPA selected 1.4 [[Page 28342]] as a reasonable estimate of occupational relative risk for further analysis. --------------------------------------------------------------------------- \33\ Bhatia, R., Lopipero, P., Smith, A. (1998). Diesel exhaust exposure and lung cancer. Epidemiology 9(1):84-91. \34\ Lipsett, M: Campleman, S.; (1999). Occupational exposure to diesel exhaust and lung cancer: a meta-analysis. Am J Public Health 80(7):1009-1017. --------------------------------------------------------------------------- EPA generally derives cancer unit risk estimates to calculate population risk more precisely from exposure to carcinogens. In the simplest terms, the cancer unit risk is the increased risk associated with average lifetime exposure of 1 ug/m\3\. EPA concluded in the Diesel HAD that it is not possible currently to calculate a cancer unit risk for diesel exhaust due to a variety of factors that limit the current studies, such as a lack of standard exposure metric for diesel exhaust and the absence of quantitative exposure characterization in retrospective studies. EPA generally derives cancer unit risk estimates to calculate population risk more precisely from exposure to carcinogens. In the simplest terms, the cancer unit risk is the increased risk associated with average lifetime exposure of 1 ug/m\3\. EPA concluded in the Diesel HAD that it is not possible currently to calculate a cancer unit risk for diesel exhaust due to a variety of factors that limit the current studies, such as lack of an adequate dose-response relationship between exposure and cancer incidence. However, in the absence of a cancer unit risk, the EPA Diesel HAD sought to provide additional insight into the possible ranges of risk that might be present in the population. Such insights, while not confident or definitive, nevertheless contribute to an understanding of the possible public health significance of the lung cancer hazard. The possible risk range analysis was developed by comparing a typical environmental exposure level to a selected range of occupational exposure levels and then proportionally scaling the occupationally observed risks according to the exposure ratio's to obtain an estimate of the possible environmental risk. If the occupational and environmental exposures are similar, the environmental risk would approach the risk seen in the occupational studies whereas a much higher occupational exposure indicates that the environmental risk is lower than the occupational risk. A comparison of environmental and occupational exposures showed that for certain occupations the exposures are similar to environmental exposures while, for others, they differ by a factor of about 200 or more. The first step in this process is to note that the occupational relative risk of 1.4, or a 40 percent from increased risk compared to the typical 5 percent lung cancer risk in the U.S. population, translates to an increased risk of 2 percent (or 10-2) for these diesel exhaust exposed workers. The Diesel HAD derived a typical nationwide average environmental exposure level of 0.8 ug./m\3\ for diesel PM from highway sources for 1996. Diesel PM is a surrogate for diesel exhaust and, as mentioned above, has been classified as a carcinogen by some agencies. This estimate was based on national exposure modeling; the derivation of this exposure is discussed in detail in the EPA Diesel HAD. The possible risk range in the environment was estimated by taking the relative risks in the occupational setting, EPA selected 1.4 and converting this to absolute risk of 2% and then ratioing this risk by differences in the occupational vs environmental exposures of interest. A number of calculations are needed to accomplish this, and these can be seen in the EPA Diesel HAD. The outcome was that environmental risks from diesel exhaust exposure could range from a low of 10-4 to 10-5 or be as high as 10-3 this being a reflection of the range of occupational exposures that could be associated with the relative and absolute risk levels observed in the occupational studies. While these risk estimates are exploratory and not intended to provide a definitive characterization of cancer risk, they are useful in gauging the possible range of risk based on reasonable judgement. It is important to note that the possible risks could also be higher or lower and a zero risk cannot be ruled out. Some individuals in the population may have a high tolerance to exposure from diesel exhaust and low cancer susceptibility. Also, one cannot rule out the possibility of a threshold of exposure below which there is no cancer risk, although evidence has not been seen or substantiated on this point. Also, as discussed in the Diesel HAD, there is a relatively small difference between some occupational settings where increased lung cancer risk is reported and ambient environmental exposures. The potential for small exposure differences underscores the appropriateness of the extrapolation from occupational risk to ambient environmental exposure levels is reasonable and appropriate. EPA also recently completed an assessment of air toxic emissions (the National-Scale Air Toxics Assessment or NATA) and their associated risk, and we concluded that diesel exhaust ranks with other substances that the national-scale assessment suggests pose the greatest relative risk.\35\ This assessment estimates average population inhalation exposures to diesel PM in 1996 for nonroad as well as on-road sources. These are the sum of ambient levels in various locations weighted by the amount of time people spend in each of the locations. This analysis shows a somewhat higher diesel exposure level than the 0.8 ug/m\3\ used to develop the risk perspective in the Diesel HAD. The NATA levels are 1.4 ug/m\3\ total with an on-road source contribution of 0.5 ug/m\3\ to average nationwide exposure in 1996 and a nonroad source contribution of 0.9 ug/m\3\. The average urban exposure concentration was 1.6 ug/ m\3\ and the average rural concentration was 0.55 ug/m\3\. In five percent of urban census tracts across the United States, average concentrations were above 4.3 ug/m\3\. The Diesel HAD states that use of the NATA exposure number results instead of the 0.8 ug/m\3\ results in a similar risk perspective. --------------------------------------------------------------------------- \35\ U.S. EPA (2002). National-Scale Air Toxics Assessment. This material is available electronically at http://www.epa.gov/ttn/atw/ nata/. --------------------------------------------------------------------------- In 2001, EPA completed a rulemaking on mobile source air toxics with a determination that diesel particulate matter and diesel exhaust organic gases be identified as a Mobile Source Air Toxic (MSAT).\36\ This determination was based on a draft of the Diesel HAD on which the Clean Air Scientific Advisory Committee of the Science Advisory Board had reached closure. The purpose of the MSAT list is to provide a screening tool that identifies compounds emitted from motor vehicles or their fuels for which further evaluation of emissions controls is appropriate. --------------------------------------------------------------------------- \36\ U.S. EPA (2001). Control of Emissions of Hazardous Air Pollutants from Mobile Sources; Final Rule. 66 FR 17230-17273 (March 29, 2001). --------------------------------------------------------------------------- In summary, even though EPA does not have a specific carcinogenic potency with which to accurately estimate the carcinogenic impact of diesel PM, the likely hazard to humans at environmental exposure levels leads us to conclude that diesel exhaust emissions of PM and organic gases should be reduced from nonroad engines in order to protect public health. ii. Other Health Effects of Diesel Exhaust The acute and chronic exposure-related effects of diesel exhaust emissions are also of concern to the Agency. The Diesel HAD established an inhalation Reference Concentration (RfC) specifically based on animal studies of diesel exhaust. An RfC is defined by EPA as ``an estimate of a continuous inhalation exposure to the human population, including sensitive subgroups, with uncertainty spanning [[Page 28343]] perhaps an order of magnitude, that is likely to be without appreciable risks of deleterious noncancer effects during a lifetime.'' EPA derived the RfC from consideration of four chronic rat inhalation studies showing adverse pulmonary effects. The diesel RfC is based on a ``no observable adverse effect'' level of 144 ug/m\3\ that is further reduced by applying uncertainty factors of 3 for interspecies extrapolation and 10 for human variations in sensitivity. The resulting RfC derived in the Diesel HAD is 5 ug/m\3\ for diesel exhaust as measured by diesel PM. This RfC does not consider allergenic effects such as those associated with asthma or immunologic effects. There is growing evidence that diesel exhaust can exacerbate these effects, but the exposure-response data is presently lacking to derive an RfC. Again, this RfC is based on animal studies and is meant to estimate exposure that is unlikely to have deleterious effects on humans based on those studies alone. The Diesel HAD also briefly summarizes health effects associated with ambient PM and the EPA's annual NAAQS for PM2.5 of 15 ug/m\3\. There is a much more extensive body of human data showing a wide spectrum of adverse health effects associated with exposure to ambient PM, of which diesel exhaust is an important component due to its large contribution to ambient concentrations. The RfC is not meant to say that 5 ug/m\3\ provides adequate public health protection for ambient PM2.5. There may be benefits to reducing diesel PM below 5 ug/m\3\ since diesel PM is a major contributor to ambient PM2.5. Recent epidemiologic studies of ambient PM2.5 do not indicate a threshold of effects at low concentrations.\37\ --------------------------------------------------------------------------- \37\ EPA-SAB-Council-ADV-99-012, 1999. The Clean Air Act Amendments Section 812 Prospective Study of Costs and Benefits (1999): Advisory by the Health and Ecological Effects Subcommittee on Initial Assessments of Health and Ecological Effects, Part 1. July 28, 1999. --------------------------------------------------------------------------- Also, as mentioned earlier in the health effects discussion for PM2.5, there are a number of other health effects associated with PM in general, and motor vehicle exhaust including diesels in particular, that provide additional evidence for the need for significant emission reductions from nonroad diesel sources. For example, the Diesel HAD notes that acute or short-term exposure to diesel exhaust can cause acute irritation (e.g., eye, throat, bronchial), neurophysiological symptoms (e.g., lightheadedness, nausea), and respiratory symptoms (e.g., cough, phlegm). There is also evidence for an immunologic effect such as the exacerbation of allergenic responses to know allergens and asthma-like symptoms. All of these health effects plus the designation of diesel exhaust as a likely human carcinogen provide ample health justification for control. iii. Ambient Levels and Exposure to Diesel Exhaust PM Because diesel PM is part of overall ambient PM and cannot be easily distinguished from overall PM, we do not have direct measurements of diesel PM in the ambient air. Ambient diesel PM concentrations are estimated instead using one of three approaches: (1) Ambient air quality modeling based on diesel PM emission inventories; (2) using elemental carbon concentrations in monitored data as surrogates; or (3) using the chemical mass balance (CMB) model in conjunction with ambient PM measurements. (Also, in addition to CMB, UNMIX/PMF have also been used). Estimates using these three approaches are described below. In addition, estimates developed using the first two approaches above are subjected to a statistical comparison to evaluate overall reasonableness of estimated concentrations. It is important to note that, while there are inconsistencies in some of these studies on the relative importance of gasoline and diesel PM, the studies which are discussed in the Diesel HAD all show that diesel PM is a significant contributor to overall ambient PM. Some of the studies differentiate nonroad from on-road diesel PM. (1) Air Quality Modeling In addition to the general ambient PM modeling conducted for this proposal, diesel PM concentrations specifically were recently estimated for 1996 as part of NATA. In this assessment, the PM inventory developed for the recent regulation promulgating 2007 heavy duty vehicle standards was used. Note that the nonroad inventory used in this modeling was based on an older version of the draft NONROAD Model which showed higher diesel PM than the current version. Ambient impacts of mobile source emissions were predicted using the Assessment System for Population Exposure Nationwide (ASPEN) dispersion model. Overall mean annual national levels for both on-road and nonroad diesels of 2.06 ug/m\3\ diesel PM were calculated with a mean of 2.41 in urban counties and 0.74 in rural counties. These are ambient levels such as would be seen at monitors rather than the exposure levels discussed earlier. Over half of the diesel PM comes from nonroad diesels. Diesel PM concentrations were also recently modeled across a representative urban area, Houston, for 1996, using the Industrial Source Complex Short Term (ISCST3) model. This modeling is designed to more specifically account for local traffic patterns including diesel truck traffic along specific roadways. The modeling in Houston suggests strong spatial gradients for Diesel PM and indicates that ``hotspot'' concentrations can be very high, up to 8 ug/m\3\ at receptor versus a 3 ug/m\3\ average in Houston. Such concentrations are above the RfC for diesel exhaust and indicate a potential for adverse health effects from chronic exposure to diesel PM. These results also suggest that PM from diesel vehicles makes a major contribution to total ambient PM concentrations. Such ``hot spot'' concentrations along certain roadways suggest the presence of both high localized exposures plus higher estimated average annual exposure levels for urban centers than what has been estimated in assessments such as NATA, which are designed to focus on regional and national scale averages. There are similar ``hot spot'' concentrations in the immediate vicinity of use of nonroad equipment such as in urban construction sites. (2) Elemental Carbon Measurements As mentioned before, the carbonaceous component is significant in ambient PM. The carbonaceous component consists of organic carbon and elemental carbon. Monitoring data on elemental carbon concentrations can be used as a surrogate to determine ambient diesel PM concentrations. Elemental carbon is a major component of diesel exhaust, contributing to approximately 60 to 80 percent of diesel particulate mass, depending on engine technology, fuel type, duty cycle, lube oil consumption, and state of engine maintenance. In most areas, diesel engine emissions are major contributors to elemental carbon in the ambient air, with other potential sources including gasoline exhaust, combustion of coal, oil, or wood (including forest fires), charbroiling, cigarette smoke, and road dust. Because of the large portion of elemental carbon in diesel particulate matter, and the fact that diesel exhaust is one of the major contributors to elemental carbon in most areas, ambient diesel PM concentrations can be bounded using elemental carbon measurements. The measured mass of elemental carbon at a given site varies depending on the measurement technique used. Moreover, to estimate diesel PM concentration based on elemental [[Page 28344]] carbon level, one must first estimate the percentage of PM attributable to diesel engines and the percentage of elemental carbon in diesel PM. Thus, there are significant uncertainties in estimating diesel PM concentrations using an elemental carbon surrogate. Depending on the measurement technique used, and assumptions made, average nationwide concentrations for current years of diesel PM estimated from elemental carbon data range from about 1.2 to 2.2 ug/m\3\. EPA has compared these estimates based on elemental carbon measurements to modeled concentrations in NATA and concluded that the two sets of data agree reasonably well. This performance compares favorably with the model to monitor results for other pollutants assessed in NATA, with the exception of benzene, for which the performance of the NATA modeling was better. These comparisons are discussed in greater detail in the draft RIA. (3) Chemical Mass Balance The third approach for estimating ambient diesel PM concentrations uses the CMB model for source apportionment in conjunction with ambient PM measurements and chemical source ``fingerprints'' to estimate ambient diesel PM concentrations. The CMB model uses a statistical fitting technique to determine how much mass from each source would be required to reproduce the chemical fingerprint of each speciated ambient monitor. This source apportionment technique presently does not distinguish between on-road and nonroad but, instead, gives diesel PM as a whole. This source apportionment technique can distinguish between diesel and gasoline PM. Caution in interpreting CMB results is warranted, as the use of fitting species that are not specific to the sources modeled can lead to misestimation of source contributions. Ambient concentrations using this approach are generally about 1 ug/ m\3\ annual average. UNMIX/PMF models show similar results. Results from various studies are discussed in the draft RIA. iv. Diesel Exhaust PM Exposures Exposure of people to diesel exhaust depends on their various activities, the time spent in those activities, the locations where these activities occur, and the levels of diesel exhaust pollutants (such as particulate) in those locations. The major difference between ambient levels of diesel particulate and exposure levels for diesel particulate is that exposure accounts for a person moving from location to location, proximity to the emission source, and whether the exposure occurs in an enclosed environment. (1) Occupational Exposures Diesel particulate exposures have been measured for a number of occupational groups over various years but generally for more recent years (1980s and later) rather than earlier years. Occupational exposures had a wide range varying from 2 to 1,280 ug/m3 for a variety of occupational groups including miners, railroad workers, firefighters, air port crew, public transit workers, truck mechanics, utility linemen, utility winch truck operators, fork lift operators, construction workers, truck dock workers, short-haul truck drivers, and long-haul truck drivers. These individual studies are discussed in the Diesel HAD. As discussed in the Diesel HAD, the National Institute of Occupational Safety and Health (NIOSH) has estimated a total of 1,400,000 workers are occupationally exposed to diesel exhaust from on- road and nonroad equipment. Many measured or estimated occupational exposures are for on-road diesel engines although some (especially the higher ones) are for occupational groups (e.g., fork lift operators, construction workers, or mine workers) who would be exposed to nonroad diesel exhaust. Sometimes, as is the case for the nonroad engines, there are only estimates of exposure based on the length of employment or similar factors rather than a ug/m3 level. Estimates for exposures to diesel PM for diesel fork lift operators have been made that range from 7 to 403 ug/m3 as reported in the Diesel HAD. In addition, the Northeast States for Coordinated Air Use Management (NESCAUM) is presently measuring occupational exposures to particulate and elemental carbon near the operation of various diesel non-road equipment. Exposure groups include agricultural farm operators, grounds maintenance personnel (lawn and garden equipment), heavy equipment operators conducting multiple job tasks at a construction site, and a saw mill crew at a lumber yard. Samples will be obtained in the breathing zone of workers. Some initial results are expected in late 2003. (2) General Ambient Exposures Currently, personal exposure monitors for PM cannot differentiate diesel from other PM. Thus, we use modeling to estimate exposures. Specifically, exposures for the general population are estimated by first conducting dispersion modeling of both on-road and non-road diesel emissions, described above, and then by conducting exposure modeling. The most comprehensive modeling for cumulative exposures to diesel PM is the NATA. This assessment calculates exposures of the national population as a whole to a variety of air toxics, including diesel PM. As discussed previously, the ambient levels are calculated using the ASPEN dispersion model. The preponderance of modeled diesel PM concentrations are within a factor of 2 of diesel PM concentrations estimated from elemental carbon measurements.\38\ This comparison adds credence to the modeled ASPEN results and associated exposure assessment. --------------------------------------------------------------------------- \38\ U.S. EPA (2002). D [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%3A03-9737. Public record. Not legal advice.