# Control of Emissions of Hazardous Air Pollutants From Mobile Sources > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A01-37 ## Record - **Collection:** Federal Register - **Document type:** Rule - **Published:** March 29, 2001 - **Citation:** 66 FR 17230 ## Text ENVIRONMENTAL PROTECTION AGENCY 40 CFR Parts 80, and 86 [AMS-FRL-6924-1] RIN 2060-AI55 Control of Emissions of Hazardous Air Pollutants From Mobile Sources AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: Today's action addresses emissions of hazardous air pollutants (HAPs) from motor vehicles and their fuels. Hazardous air pollutants refer to a range of compounds that are known or suspected to have serious health or environmental impacts. Motor vehicles are significant contributors to national emissions of several hazardous air pollutants, notably benzene, formaldehyde, 1,3-butadiene, acetaldehyde, and diesel particulate matter and diesel exhaust organic gases. In today's action, we list 21 compounds emitted from motor vehicles that are known or suspected to cause cancer or other serious health effects. Our Mobile Source Air Toxics (MSAT) list includes various volatile organic compounds (VOCs) and metals, as well as diesel particulate matter and diesel exhaust organic gases (collectively DPM + DEOG). The selection methodology we used to develop this MSAT list, which may be used to add compounds to or remove compounds from the list in the future as new information becomes available, is also described. In today's action we also examine the mobile source contribution to national inventories of these emissions and the impacts of existing and newly promulgated mobile source control programs, including our reformulated gasoline (RFG) program, our national low emission vehicle (NLEV) standards, our Tier 2 motor vehicle emissions standards and gasoline sulfur control requirements, and our proposed heavy-duty engine and vehicle standards and on-highway diesel fuel sulfur control requirements. Between 1990 and 2020, we project these programs will reduce on-highway emissions of benzene, formaldehyde, 1,3-butadiene, and acetaldehyde by 67 to 76 percent, and will reduce on-highway diesel PM emissions by 90 percent. This action also finalizes new gasoline toxic emission baseline requirements which require refiners to maintain current levels of over-compliance with toxic emissions performance standards that apply to federal reformulated gasoline (RFG) and anti-dumping standards that apply to conventional gasoline (CG). Because the new baseline requirements do not require refiners to install new equipment or use technologies beyond what they were using in the baseline period (1998-2000), we project that this program will impose only negligible costs. The new baseline requirements are designed to prevent backsliding and to ensure that existing overcompliance with current standards continues. We are not setting additional vehicle-based air toxics controls at this time because the technology-forcing Tier 2 light-duty vehicle standards and those standards being developed in response to our recent proposal for heavy-duty engine and vehicle standards represent the greatest degree of toxics control achievable at this time considering existing standards, the availability and cost of the technology, and noise, energy, and safety factors, and lead time. Finally, because of our continuing concern about the potential health impacts of public exposure to air toxics, today's action also describes a Technical Analysis Plan through which we will continue to improve our understanding of the risk posed by air toxics to public health and welfare. It will also allow us to evaluate the need for and appropriateness of additional mobile source air toxics controls for on-highway and nonroad sources, and their fuels. Based on the information developed through this technical analysis plan, we will conduct a future rulemaking, to be completed no later than July 1, 2004. DATES: This rule is effective May 29, 2001. The incorporation by reference of certain publications listed in this rule is approved by the Director of the Federal Register as of May 29, 2001. ADDRESSES: Comments: All comments and materials relevant to today's action have been placed in Public Docket No. A-2000-12 at the following address: U.S. Environmental Protection Agency (EPA), Air Docket (6102), Room M-1500, 401 M Street, SW, Washington, DC 20460. EPA's Air Docket makes materials related to this rulemaking available for review at the above address (on the ground floor in Waterside Mall) from 8:00 a.m. to 5:30 p.m., Monday through Friday, except on government holidays. You can reach the Air Docket by telephone at (202) 260-7548, and by facsimile (202) 260-4400. We may charge a reasonable fee for copying docket materials, as provided in 40 CFR part 2. FOR FURTHER INFORMATION CONTACT: Margaret Borushko, U.S. EPA, National Vehicle and Fuels Emission Laboratory, 2000 Traverwood, Ann Arbor, MI 48105; Telephone (734) 214-4334; FAX: (734) 214-4816; E-mail: borushko.margaret@epa.gov SUPPLEMENTARY INFORMATION: Regulated Entities This action will affect entities that produce new motor vehicles, alter individual imported motor vehicles to address U.S. regulation, or convert motor vehicles to use alternative fuels. It will also affect entities that produce, distribute, or sell gasoline or diesel motor fuel. The table below gives some examples of entities that may have to follow the regulations. Because these are only examples, you should carefully examine the regulations in 40 CFR parts 80 and 86. If you have questions, call the person listed in the FOR FURTHER INFORMATION CONTACT section above. Category NAICS codes (1) SIC codes (2) Examples of potentially regulated entities Industry 336111 3711 Motor Vehicle Manufacturers. 336112 336120 Industry 336112 3711 Engine and Truck Manufacturers. 336120 Industry 336311 3592 Alternative Fuel Vehicle Converters. 336312 3714 422720 5172 454312 5984 811198 7549 541514 8742 541690 8931 Industry 811112 7533 Commercial Importers of Vehicles and Vehicle Components. 811198 7549 541514 8742 Industry 324110 2911 Petroleum Refiners. Industry 422710 5171 Gasoline or Diesel Marketers and Distributors. 422720 5172 Industry 484220 4212 Gasoline or Diesel Carriers. 484230 4213 (1) North American Industry Classification System (NAICS). (2) Standard Industrial Classification (SIC) system code. Access to Rulemaking Documents through the Internet Today's action is available electronically on the day of publication from the Office of the Federal Register Internet Web site listed below. Electronic copies of this preamble and regulatory language as well as the Response to Comments, the Technical Support Document (TSD) and other documents associated with today's action will be available from the EPA Office of Transportation and Air Quality Web site listed below shortly after the rule is signed by the Administrator. This service is free of charge, except any cost that you already incur for Internet connectivity. EPA Federal Register Web Site: http://www.epa.gov/docs/fedrgstr/epa-air/ (Either select a desired date or use the Search feature.) Office of Transportation and Air Quality (OTAQ) Air Toxics Web Site: http://www.epa.gov/otaq/toxics.htm Please note that due to differences between the software used to develop the document and the software into which the document may be downloaded, changes in format, page length, etc., may occur. Outline of this Preamble I. Introduction A. Background B. Basic Components of Today's Program 1. Identification of Mobile Source Air Toxics 2. Assessment of Emission Benefits From Current Standards 3. Consideration of Additional On-Highway Controls 4. Nonroad Air Toxics 5. Technical Analysis Plan and Commitment for Further Rulemaking C. EPA's Statutory Authority for Today's Action II. What Are the Mobile Source Air Toxics? A. Introduction B. The Methodology Used to Identify Our List of Mobile Source Air Toxics 1. Identifying Pollutants Emitted From Mobile Sources 2. Using IRIS to Identify Pollutants With Potential Serious Adverse Health Effects C. List of Mobile Source Air Toxics III. How Are Motor Vehicle Emission Control Programs Reducing MSAT Emissions? A. Baseline Inventories B. Impacts of Motor Vehicle Emission Controls on Emissions Inventories 1. Description of Emission Control Programs 2. Emission Reductions From Control Programs IV. Evaluation of Additional Motor Vehicle-based Controls A. MSATs and Motor Vehicle-based Controls B. Vehicle-based Standards to Reduce MSATs From Light-Duty Vehicles C. Vehicle-based Standards to Reduce MSATs From Heavy-Duty Engines D. Conclusions Regarding Vehicle-based Standards V. Evaluation of Additional Fuel-Based Controls A. Form of the Rule 1. What Is the Form of the Rule EPA Is Promulgating Today? 2. Why Did EPA Change From the Proposed Benzene Fuel Content Form of the Rule to the TPR? 3. What Are the Benefits of the TPR? 4. What Are the Costs of the TPR? B. Issues and Areas of Comment on Non-implementation Related Aspects of the Program 1. What Is the Relationship Between the RFG and Anti-dumping Requirements and the Toxics Anti-backsliding Requirements? 2. How Are Incremental Production Volumes of RFG Affected by This Rule? 3. Does This Rule Contain Any Small Refiner Provisions? 4. Is This Rule Expected to Constraint the Potential for Expanded Use of Ethanol in Conventional Gasoline? 5. Is Diesel Fuel Control a Part of Today's Regulation? C. What Are the Components of the Anti-backsliding Toxics Performance Program? 1. Start Date 2. Separate Compliance Determination for RFG and CG 3. Baseline Development and Submittal 4. Baseline Adjustment 5. Compliance Margin 6. Foreign Refiner Provisions 7. Default Baseline and Applicability 8. Compliance Period and Deficit and Credit Carryforward 9. Hardship Provisions 10. California Gasoline 11. Territories 12. Gasoline excluded D. Why Isn't EPA Adopting Other Fuel Controls to Control MSATs? VI. Nonroad Sources of MSAT Emissions A. Nonroad MSAT Baseline Inventories B. Impacts of Current Nonroad Mobile Source Emission Control Strategies 1. Description of the Emission Control Program 2. Emission Reductions From Current Programs C. Gaps in Nonroad Mobile Source Data VII. Technical Analysis Plan to Address Data Gaps and Commitment for Further Rulemaking A. Technical Analysis Plan to Address Data Gaps B. Commitment for Further Rulemaking VIII. Public Participation IX. Administrative Requirements A. Administrative Designation and Regulatory Analysis B. Regulatory Flexibility Analysis C. Paperwork Reduction Act D. Intergovernmental Relations 1. Unfunded Mandates Reform Act 2. Executive Order 13132: Federalism 3. Executive Order 13084: Consultation and Coordination With Indian Tribal Governments E. National Technology Transfer and Advancement Act F. Executive Order 13045: Children's Health Protection G. Congressional Review Act X. Statutory Provisions and Legal Authority I. Introduction A. Background Air toxics, which are also known as “hazardous air pollutants” or HAPs, are those pollutants known or suspected to cause cancer or other serious health or environmental effects. They include pollutants like benzene, perchloroethylene, methylene chloride, heavy metals like mercury and lead, polychlorinated biphenyls (PCBs), and dioxins. While the harmful effects of air toxics are of particular concern in areas closest to where they are emitted, they can also be transported and affect the health and welfare of populations in other geographic areas. Some can persist for considerable time in the environment and/or bioaccumulate in the food chain. To address concerns about the potentially serious impacts of hazardous air pollutants on public health and the environment, the Clean Air Act (the Act), as amended in 1990, includes a number of provisions that have led EPA to characterize, prioritize, and control these emissions as appropriate. Since 1990, the Agency has worked to comply with the Act through a combination of regulatory approaches, partnerships, ongoing research and assessments, risk initiatives, and education and outreach. We have put in place many programs to reduce air toxic emissions that have resulted, and will continue to result, in reductions in ambient concentrations of air toxics. On the stationary source side, we have developed 46 stationary source standards for 82 different types of sources and have more under development. These standards are required under Sections 112 and 129 of the Act and provide for future evaluation of the need for additional stationary source regulations based on the remaining risk from air toxics after these standards are in effect. These actions have resulted, or are projected to result in, substantial reductions in HAP emissions. On the mobile source side, many of the emission control programs put in place pursuant to the 1990 Clean Air Act Amendments reduce air toxics emissions from a wide variety of mobile sources. These include our reformulated gasoline (RFG) program, which has substantially reduced mobile source air toxics, particularly in urban areas which often have high levels of ambient air toxics, our national low emission vehicle (NLEV) program, our Tier 2 motor vehicle emissions standards and gasoline sulfur control requirements, and standards for nonroad vehicles and equipment, such as locomotives, recreational marine engines, and aircraft. We have also proposed heavy-duty engine and vehicle standards and on-highway diesel fuel sulfur control requirements that would reduce toxics emissions from heavy-duty trucks. 1 Finally, certain other mobile source control programs have been specifically aimed at reducing toxics emissions from mobile sources (e.g., our lead phase-out programs). 1 See final rules: NLEV, 62 FR 31191 (June 6, 1997); Tier 2, 65 FR 6698 (February 10, 2000); land-based diesel nonroad, 63 FR 56968 (October 23, 1998); locomotive, 63 FR 18978 (April 16, 1998); recreational marine, 61 FR 52088 (October 4, 1996); commercial diesel marine, 64 FR 73300 (December 29, 1999); aircraft, 62 FR 25355 (May 8, 1997); RFG, 59 FR 7812 (February 16, 1994). See proposed rule HD2007, 65 FR 35430 (June 2, 2000). While these mobile source standards were put in place primarily to reduce ambient concentrations of criteria pollutants through oxides of nitrogen (NO X ), volatile organic compound (VOC), carbon monoxide (CO) and particulate matter (PM) controls, and thereby to help states and localities come into attainment with the National Ambient Air Quality Standards (NAAQS) for ozone, PM, and CO, they have reduced and will continue to reduce on-highway emissions of air toxics significantly. 2 By 2020, we project these programs will reduce the levels of on-highway emissions of benzene by 73 percent, formaldehyde by 76 percent, 1,3-butadiene by 72 percent, and acetaldehyde by 67 percent from 1990 levels. In addition, by 2020, on-highway diesel PM emission reductions of 94 percent from 1990 levels are projected in a recent NPRM for heavy-duty engines. 3 2 For example, included among the numerous chemicals that make up total VOC emissions—that thus are reduced when VOCs are reduced—are several gaseous toxics (e.g., benzene, formaldehyde, 1,3-butadiene, and acetaldehyde). 3 65 FR 35430, June 2, 2000. Nevertheless, because of the potentially serious effects exposure to air toxics may have on human health, it is reasonable to assess whether it is appropriate to establish additional mobile source controls that are specifically designed to reduce further or minimize increases in national inventories of these pollutants. In today's action, pursuant to Section 202(l)(2) of the Act, the Agency has identified those compounds emitted from mobile sources that should be classified as mobile source air toxics, evaluated whether there are additional controls that can be established at this time, set new toxic emission performance standards, identified existing data gaps in our understanding of the risk posed to the public from mobile source air toxics, and committed to reevaluate the need for additional controls in 2003-2004. Today's action provides the mobile source component of EPA's National Air Toxics Program: The Integrated Urban Strategy (IUATS), published July 19, 1999 (64 FR 38706). The overarching goal of the IUATS is to reduce cancer and noncancer risks associated with all sources of air toxics in urban areas. In urban areas, toxic air pollutants raise special concerns because sources of emissions and people are concentrated in the same geographic areas, leading to large numbers of people being exposed to the emissions of many HAPs from many sources. The IUATS identified 33 “urban HAPs” which pose the greatest threat to human health in the largest number of urban areas. These 33 compounds are a subset of the 188 compounds listed in Section 112(b) of the Clean Air Act and are listed in Table I-1. Thirteen of these compounds are also included on our Mobile Source Air Toxics list (see Section II, below). The IUATS is described in greater detail in Chapter 1 of the Technical Support Document for this rule. Additional information can also be obtained from the EPA's Unified Air Toxics website, http://www.epa.gov/ttn/uatw . Table I-1.—List of Urban HAPs for the Integrated Urban Air Toxics Strategy Acetaldehyde a Coke oven emissions Mercury compounds a Acrolein a 1,2-dibromomethane Methylene chloride. Acrylonitrile 1,2-dichloropropane (propylene dichloride) Nickel compounds. a Arsenic compounds a 1,3-dichloropropene Polychlorinated biphenyls. Benzene a Ethyl dichloride (1,2- Polycyclic organic matter. a Beryllium compounds Ethylene oxide Quinoline. 1,3-Butadiene a Formaldehyde a 2,3,7,8-tetrachlorodibenzo-p-dioxine (and cogeners and TCDF cogeners). a Cadmium compounds Hexachlorobenzene 1,1,2,2-tetrachloroethane. Carbon tetrachloride Hydrazine Tetrachloroethylene. Chloroform Lead compounds a Trichloroethylene. Chromium compounds a Manganese compounds a Vinyl chloride. a Included on our Mobile Source Air Toxics list. Today's rule is our first attempt at addressing mobile source air toxics in a systematic and integrated manner. Additional analysis, however, will be necessary to evaluate the sufficiency of those controls and to determine whether there is a need for additional controls. Today's rule also contains a Technical Analysis Plan (TAP) that identifies key information gaps about the risk posed by mobile source air toxics and the feasibility of additional controls. In order to address these data gaps, the Agency will continue to compile, analyze, and conduct additional research in coordination with other toxics research activities that are ongoing in the Agency, including the National-Scale Air Toxics Assessment (NATA) headed by EPA's Office of Air Quality Planning and Standards (OAQPS) and the Air Toxics Research Strategy (ATRS) headed by EPA's Office of Research and Development (ORD). The results of NATA will be used to identify areas of the country and pollutants where additional investigation is needed. NATA will begin with an analysis of the risks associated with the 33 “urban HAPs” identified in Table I-1. In the future, NATA will evaluate all 188 HAPs currently listed under Section 112(b) of the Act as well as diesel PM. NATA is described in greater detail in Chapter 1 of the Technical Support Document for this rule. Additional information can also be obtained from the NATA website (http://www.epa.gov/ttn/uatw/nata). The Air Toxics Research Strategy (ATRS) is an Agency 10 year plan to guide and prioritize research in air toxics from various sources, including mobile sources. ATRS is also described in Chapter 1 of the Technical Support Document. With this background, we now turn to an overview of today's action. B. Basic Components of Today's Program Today's action addresses mobile source air toxics emissions. In it, we identify our list of 21 mobile source air toxics (MSATs) and set new gasoline toxic emission performance baseline requirements for RFG and conventional gasoline. We also describe a Technical Analysis Plan to continue analysis and research that will aid us in evaluating and assessing the need for additional mobile source air toxics controls. The information acquired through our technical analysis will form the basis for a future mobile source air toxics rulemaking. 1. Identification of Mobile Source Air Toxics There are hundreds of different compounds and elements that are known to be emitted from passenger cars, on-highway trucks, and various types of nonroad equipment. Section II of today's action identifies a list of 21 toxic compounds emitted from motor vehicles and describes the methodology we used to generate this list. This methodology may be used to add compounds to, or remove compounds from, the MSAT list in the future as new information becomes available. 2. Assessment of Emission Benefits From Current Standards Today's action also describes how our current mobile source emission control programs are expected to reduce MSAT emissions. By 2020, we expect existing programs like the reformulated gasoline (RFG) program, national low emission vehicle (NLEV) program, Tier 2 motor vehicle emissions standards and gasoline sulfur control requirements (Tier 2), and our proposed heavy-duty engine and vehicle standards and on-highway diesel fuel sulfur control requirements (HD2007 rule), to significantly reduce on-highway emissions of key air toxics. Section III contains our on-highway toxics emissions inventory analysis and estimates of these expected reductions. 3. Consideration of Additional On-Highway Controls Although we anticipate substantial reductions in emissions of key toxic pollutants by 2020, the serious potential health effects associated with many of these compounds lead us to evaluate whether additional controls are technologically feasible at this time. For the purpose of our analysis, we divide potential control measures into two broad categories: vehicle-based controls and fuel-based controls. Vehicle-based controls include programs that reduce evaporative and exhaust emissions from vehicles and engines. Fuel-based controls explore how changing fuel formulation can reduce air toxic emissions. In performing our analysis of additional controls in Sections IV and V, we followed the requirements specified in Section 202(l)(2) of the Act: these motor vehicle or motor fuel standards must “reflect the greatest degree of emission reduction achievable through the application of technology which will be available, taking into consideration the standards established under [Section 202(a)], the availability and costs of the technology, and noise, energy, and safety factors, and lead time.” Based on our analysis and the comments we received from various stakeholders, we are finalizing gasoline toxic emission performance standards that will help maintain current levels of overcompliance with existing gasoline toxics emission standards. These requirements are refiner-specific, based on each refinery's average 1998-2000 gasoline toxic emission performance levels for RFG and conventional gasoline. Consistent with our proposal, we are not setting additional air toxics emissions standards for motor vehicles in today's action. However, it is important to note that we have proposed stringent new diesel particulate matter standards for heavy-duty vehicles (HDV) that would reduce HDV PM emissions by 90%. We expect to issue a final rule for this category soon. We believe that it is not technologically feasible at this time to set additional motor vehicle controls under Section 202(l)(2) beyond the controls already adopted or proposed by the Agency. This decision is based on consideration of the technical feasibility, cost, and other factors relevant to a proposal of further controls at this time. 4. Nonroad Air Toxics Section 202(l)(2) of the Act specifies that we set standards to control hazardous air pollutants from motor vehicles and motor vehicle fuels which, by definition, do not include nonroad engines or vehicles or their fuels. However, nonroad engines are also important contributors to national inventories of mobile source air toxics emissions. Therefore, we believe it is also helpful to include a discussion of nonroad sources in today's action. In addition, as noted above, today's action is part of EPA's Integrated Urban Air Toxics Strategy. As part of our effort to establish a comprehensive plan that seeks to reduce urban air toxic emissions, we intend to address both on-highway and motor vehicles and evaluate emissions and potential strategies relating to hazardous air pollutants from nonroad engines and vehicles. 5. Technical Analysis Plan and Commitment for Further Rulemaking We believe our evaluation to date of the need for, and appropriateness of, additional mobile source toxics control measures provides adequate support for today's action. At this time, EPA is also engaged in other toxics-related activities as part of NATA, the IUATS, ATRS, and other rulemaking activities. This emerging information will help us to further evaluate potential additional mobile source air toxics controls in the future. Building on these Agency toxics activities, and to increase our understanding of mobile source air toxics, we will implement the Technical Analysis Plan described in Section VII below. This Plan will be coordinated with the other research activities within the Agency in several key areas, including development of emission factors for nonroad sources, analysis of toxics exposures in microenvironments, and examination of additional fuel- and vehicle-based air toxics controls for both motor vehicles and nonroad engines and equipment. Our TAP will be fully coordinated and integrated with activities conducted as part of NATA, the IUATS, and the ATRS. This will allow us to take full advantage of what is collectively learned and provide a solid basis for future action, including a future rulemaking, to be completed no later than July 1, 2004. C. EPA's Statutory Authority for Today's Action Today's action is established pursuant to Section 202(l) of the Clean Air Act. That Section consists of two parts. Section 202(l)(1) calls on EPA to study the need for and feasibility of controlling toxic air pollutants associated with motor vehicles and motor vehicle fuels. That study is to focus on those categories of emissions that pose the greatest risk to human health or about which significant uncertainties remain. The Act specifies that, at a minimum, the study focus on emissions of benzene, formaldehyde, and 1,3-butadiene. We completed the study required under Section 202(l)(1) in April 1993. The report, entitled “Motor Vehicle-Related Air Toxics Study,” is available on our website (http://www.epa.gov/otaq/toxics.htm). Specific pollutants or pollutant categories discussed in the 1993 report include benzene, formaldehyde, 1,3-butadiene, acetaldehyde, diesel particulate, gasoline particulate, gasoline vapors, and selected metals. The emissions and exposure aspects for several of the air toxics covered in this report were recently updated in November 1999. The 1999 report, entitled “Analysis of the Impacts of Control Programs on Motor Vehicle Toxics Emissions and Exposure in Urban Areas and Nationwide,” is also available on our website, and is described in more detail in Section I.E., below. We sought peer review comments on both the 1993 and 1999 reports. We considered the 1993 comments in developing the 1999 document and will consider the 1999 comments in developing our future activities (e.g., in the development of version 4 of the Hazardous Air Pollutant Exposure Model, HAPEM4, described in Section VII, below). Section 202(l)(2) instructs us to set standards to control hazardous air pollutants from motor vehicles, motor vehicle fuels, or both. These standards, which may be revised from time to time, are to reflect the greatest degree of emission reduction achievable through the application of technology which will be available, taking into consideration the motor vehicle standards established under Section 202(a) of the Act, the availability and cost of the technology, and noise, energy and safety factors, and lead time. The regulations are to apply, at a minimum, to benzene and formaldehyde emissions, and are to be set under Section 202(a) or 211(c) of the Act. Section 211(c) of the Act authorizes the Agency to control or prohibit the manufacturer, introduction into commerce, offering for sale, or sale, of any fuel or fuel additive if any emission product of such fuel or fuel additive causes or contributes to air pollution which may reasonably be anticipated to endanger public health or welfare. II. What Are the Mobile Source Air Toxics? A. Introduction There are hundreds of different compounds and elements that are known to be emitted from passenger cars, on-highway trucks, and various nonroad equipment. Several of these compounds may have adverse effects on human health and welfare. 4 In recognition of this fact, Congress instructed EPA, in Section 202(l)(2) of the Act, to set standards for hazardous air pollutants from motor vehicles and their fuels. Except for benzene and formaldehyde (specifically mentioned in 202(l)(2)), the Act does not specify the compounds that should be considered in such a control program. Therefore, the first step in developing a mobile source air toxics control program is to identify the compounds that should be treated as hazardous air pollutants for purpose of Section 202(l)(2). Since EPA data suggest that nonroad engines and on-highway vehicles emit the same pollutants, EPA has identified this list as a list of mobile source air toxics (MSATs). 5 We are listing 21 MSATs using the methodology described below. 4 Our authority under 202(a) and 211(c) allows us to address air pollution that impacts health or welfare. This initial MSAT list focuses on human health. Additional compounds may be added in the future due to their ecological impacts, material damage, or visibility impairment and it is noteworthy that some of the MSATs on the list have important ecological impacts. 5 We have chosen to call our list of toxics a mobile sources list to acknowledge that nonroad sources may also contribute emissions of these pollutants. For purposes of Section 202(l)(2), each of the MSATs is considered a “hazardous air pollutant from motor vehicles and motor vehicle fuels.” B. The Methodology Used to Identify Our List of Mobile Source Air Toxics EPA developed the list of MSATs by first searching for lists of compounds in all available databases and recent studies (i.e., ten years old or less) which speciated emissions from motor vehicles and their fuels. Data for vehicles and engines more than ten years old are considered to be outdated and thus are judged not to be representative of current emissions. The lists did not include emissions from alternative-fueled vehicles, currently in a very small number of vehicles, such as flexible-fueled vehicles. We then compared the speciated lists of compounds in these studies to the list of compounds in EPA's Integrated Risk Information System (IRIS) database. IRIS is a database of compounds that identifies EPA's consensus scientific judgment on the characterization of the potential serious adverse health effects that may result from a lifetime exposure to a substance (discussed in more detail below). By comparing the lists of compounds provided in the emission speciation databases and studies to the list of compounds in IRIS, we generated a list of 21 compounds. An evaluation of the potential for serious adverse health effects as reflected in IRIS and in the ongoing agency scientific assessments of these compounds indicates that these compounds warrant inclusion as MSATs. It is important to note that inclusion on the list is not itself a determination by EPA that emissions of the compound in fact present a risk to public health or welfare, or that it is appropriate to adopt controls to limit the emissions of such a compound from motor vehicles or their fuels. The purpose of the list is to provide a screening tool that identifies those compounds emitted from motor vehicles or their fuels for which further evaluation of emissions controls is appropriate. In conducting any such further evaluation, pursuant to sections 202(a) or 211(c) of the Act, EPA would consider whether emissions of the compound cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare. Such an evaluation would also consider the appropriate level of any controls, based on the criteria established in section 202(l)(2). Inclusion of a compound on the MSAT list does not decide these issues, but instead identifies those compounds for which such an evaluation would appear to be warranted. With regard to emissions from alternative-fueled vehicles, most of the compounds included in the exhaust are included on our list of MSATs (e.g., formaldehyde, acetaldehyde). It should be noted that, depending on the fuel used, these vehicles may also emit unburned ethanol and methanol. EPA compared the lists of compounds emitted from motor vehicles with lists or sources of information on toxic substances other than IRIS to determine the reasonableness of the MSAT list. Based on this comparison, we requested comments on the possible addition of propionaldehyde and 2,2,4-trimethylpentane to the MSAT list. We are not adding these compounds to the MSAT list at this time due to the absence of an Agency consensus view as expressed on IRIS regarding the adverse health effects of these compounds. The MSAT list will be re-evaluated in the future as new information is acquired about emissions and/or health effects for any mobile source pollutant. Compounds may be added to or removed from the list in future rulemaking notices. 1. Identifying Pollutants Emitted From Mobile Sources In identifying a list of MSAT, EPA first searched for lists of compounds from all available databases and recent (i.e., ten years old or less) studies that speciated the emissions from motor vehicles and their fuels. Many toxic air pollutants are hydrocarbons (HCs) by their chemical nature and thus will be identified only if the HCs are chemically separated (speciated). In addition, the compounds that comprise the particulate phase of mobile source emissions must also be chemically speciated. Many test programs that characterize vehicle emissions identify only total hydrocarbons and particulate matter without separating the individual species of hydrocarbons and other elements. The databases and recent studies reporting emissions from light-duty gasoline vehicles (LDGV), heavy-duty diesel vehicles (HDDV), heavy-duty gasoline vehicles (HDGV), and gasoline-powered nonroad engines are identified in Appendix I located at the end of Chapter 2 of the TSD. Data for other vehicle and engine types (e.g., light-duty diesel engines and nonroad diesel engines) either do not exist or are outdated (more than 10 years old) and thus are judged not to be representative of current emissions. However, it is unlikely that the lack of recent data for these particular vehicle and engine types would lead us to overlook compounds that should be included on our list of MSATs, because the combustion processes for these missing vehicle and engine types are similar to those for the vehicle and engine types for which we do have data. 2. Using IRIS to Identify Pollutants With Potential Serious Adverse Health Effects The Integrated Risk Information System (IRIS) is an EPA database of scientific information that contains the Agency consensus scientific positions on the potential serious adverse health effects that may result from lifetime (chronic) exposure to substances found in the environment. 6 IRIS currently provides health effects information on over 500 specific chemical compounds. 6 EPA IRIS Database, http://www.epa.gov/iris/intro.htm IRIS contains chemical-specific summaries of qualitative and quantitative health information. IRIS information may include the reference concentration (RfC) for noncancer health effects resulting from chronic inhalation exposure, the reference dose (RfD) for noncancer health effects resulting from chronic oral exposure, and the carcinogen assessment for both oral and inhalation exposure. The RfC or RfD is an estimate (with uncertainty spanning perhaps an order of magnitude or more) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious noncancer effects during a lifetime. Because of the public health conservative methodology in deriving the RfC or RfD, it is possible that exposure above the RfC or RfD may not pose an appreciable risk; however the significance of exceedances must be evaluated on a case-by-case basis. Combined with information on specific exposure situations, the summary health hazard information in IRIS may be used in evaluating potential public health risks from environmental contaminants. IRIS also lists compounds for which the Agency has reviewed currently available information and concluded that (1) there are insufficient data to calculate an RfC or RfD for the noncancer hazard potentially posed by the compound(s), and/or (2) there is an absence of sufficient information to identify a cancer hazard. Before a substance is listed on the IRIS database, it goes through a thorough scientific evaluation. This consensus and review process, managed by EPA's Office of Research and Development (ORD), consists of (1) an annual Federal Register announcement of the IRIS agenda and a call for scientific information from the public on the selected chemical substances, (2) a search of the current literature, (3) development of health assessment and draft IRIS summaries, (4) internal EPA peer review, (5) external peer review, (6) Agency consensus review and management approval within EPA, (7) preparation of final IRIS summaries and supporting documents, and (8) entry of summaries and supporting documents into the IRIS database. C. List of Mobile Source Air Toxics In our notice of proposed rulemaking we listed 21 MSATs. We received comments on six proposed MSATs as well as other compounds. We are finalizing this list of 21 compounds, but we have changed the listing for diesel exhaust to diesel particulate matter and diesel exhaust organic gases. A discussion of the comments received on the proposed MSAT list is provided below and the MSAT list is provided in Table II-1. Table II-1.—List of Mobile Source Air Toxics (MSATs) Acetaldehyde Diesel Particulate Matter + Diesel Exhaust Organic Gases (DPM + DEOG) MTBE Acrolein Ethylbenzene Naphthalene. Arsenic Compounds 1 Formaldehyde Nickel Compounds. 1 Benzene n-Hexane POM. 3 1,3-Butadiene Lead Compounds 1 Styrene. Chromium Compounds 1 Manganese Compounds 1 Toluene. Dioxin/Furans 2 Mercury Compounds 1 Xylene. 1 Although the different metal compounds generally differ in their toxicity, the onroad mobile source inventory contains emissions estimates for total metal compounds (i.e., the sum of all forms). 2 This entry refers to two large groups of chlorinated compounds. In assessing their cancer risks, their quantitative potencies are usually derived from that of the most toxic, 2,3,7,8-tetrachlorodibenzodioxin. 3 Polycyclic Organic Matter includes organic compounds with more than one benzene ring, and which have a boiling point greater than or equal to 100 degrees centigrade. A group of seven polynuclear aromatic hydrocarbons, which have been identified by EPA as probable human carcinogens, (benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, chrysene, 7,12-dimethylbenz(a)anthracene, and indeno(1,2,3-cd)pyrene) are used here as surrogates for the larger group of POM compounds. By comparing the lists of compounds identified in the motor vehicle emission databases and studies with the toxic compounds listed in IRIS, we identified 21 compounds. Each of these pollutants are known, probable, or possible human carcinogens (Group A, B or C) and/or pollutants for which the Agency has calculated an RfC or RfD. 7 We therefore consider each of these compounds to be MSATs. 7 A further discussion of the potential cancer and noncancer risks, and other dose-response information for each MSAT can be found in Chapter 3 of the TSD. In response to public comments we are changing the way we list diesel exhaust as an MSAT. We believe a better approach is to list diesel particulate matter and diesel exhaust organic gases (DPM + DEOG) as the MSAT. This listing approach is more precise about the components of diesel exhaust expected to contribute to the observed cancer and noncancer health effects and provides a framework for developing regulatory control strategies. Currently available science, while suggesting an important role for the particulate phase component of diesel exhaust, does not attribute the serious cancer and noncancer health effects independently to diesel particulate matter separate from the organic gas phase components. Therefore, this listing approach does not constitute two separate MSAT listings but a single listing meant to capture the collection of emissions potentially responsible for the cancer and noncancer health effects related to diesel exhaust. While this listing departs slightly from the approach described above, we believe this is reasonable because (1) there are several nontoxic components of diesel exhaust (e.g., water vapor, nitrogen, oxygen) that we are excluding from the listing, (2) this listing includes the components of diesel exhaust that are likely to contribute to either the cancer or the noncancer hazard (with the exception of the gaseous phase criteria pollutants such as NO X , SO 2 and CO which are subject to National Ambient Air Quality Standards), (3) the more precise listing provides Federal and State government, industry, and public interest groups an ability to focus on the components of diesel exhaust that pose a potential concern for public health, and (4) this focus provides specific targets for emissions reductions should future analysis indicate that additional controls are necessary. Regarding the listing of metals, we have chosen to list the entire group of metal compounds if any compound of the metal has been detected in motor vehicle exhaust and any compound of the metal is listed in IRIS as potentially causing adverse human health effects. Literature values report only the total amount of the metal compound identified and not the specific form of the metal being emitted in motor vehicle exhaust. For example, chromium (Cr) can be emitted from combustion sources in different forms, the most toxic of which is Cr+6. In the literature, the form of Cr emissions from mobile sources are unidentified. In our list of MSAT, we therefore list chromium compounds generally, and do not attempt to list specific forms of these metals because we lack metal speciation information. When we assess the range of potential health impacts associated with exposure to chromium compounds, we consider the health effects associated with all forms of the compound for which we have health effects information. For chromium, the most toxic form in IRIS is Cr+6; hence the health impacts described for chromium compounds refer to these most serious effects even though it is highly unlikely that all motor vehicle emissions are Cr+6. EPA believes this listing approach is a reasonable, health-protective way to handle the uncertainty surrounding motor vehicle emissions of metals. Moreover, it is consistent with Congress' list of HAP for stationary sources in Section 112(b) of the Act. At the same time we recognize that to accurately assess the actual health risks associated with exposure to metal emissions from mobile sources, identification of the specific forms of the metals emitted would be important. With regard to emissions from alternative-fueled vehicles, most of the compounds included in the exhaust are included on our list of MSATs ( e.g., formaldehyde, acetaldehyde). It should be noted that, depending on the fuel used, these vehicles may also emit unburned ethanol and methanol. Low level ethanol mixtures (10% ethanol and 90% gasoline) are widely used in the United States. Higher level ethanol mixtures (e.g., 85% ethanol) are used as alternative fuel sources in a small number of flexible fuel vehicles. There is a paucity of data on potential inhalation effects of ethanol, and the compound is not listed in IRIS. One commenter responded to our request for comment on the addition of ethanol to the list of MSATs based on the presence of ethanol in alternative fuels and stated that ethanol should not be listed as an MSAT. At this time EPA is not including ethanol in the list of MSATs because we do not have an Agency consensus view as expressed on IRIS regarding the potential adverse health effects associated with exposure to ethanol. The Agency is continuing toxicity testing and risk assessment of potential adverse health effects resulting from exposure to this compound. We will reassess available information regarding potential health effects of exposure to ethanol when we evaluate whether additional controls are appropriate in 2003. We did not include methanol on our proposed list of MSAT because it was not identified in our analysis of speciated emissions from motor vehicles. Instead, in the NPRM, we requested comment on whether methanol and ethanol, by virtue of their use in alternative fuel vehicles, should be included on the list. During the comment period, one commenter directed EPA to studies that identify methanol as an emissions product of motor vehicles burning reformulated gasoline. This commenter suggested that further research needed to be conducted to determine whether methanol should be added to the list of MSAT. Recently submitted comments echoed the need to conduct further research and requested more time to consider the addition of methanol to the MSAT list. In order to provide a full opportunity for public comment and to respond to these comments in more detail, we will address the addition of methanol to the MSAT list in a separate rulemaking. We believe it is reasonable to defer making a decision on listing methanol until after today's rulemaking, because listing in today's rulemaking would not result in additional controls. The existing motor vehicle VOC controls will reduce emissions of methanol along with other gaseous toxics and fuel controls will need to be considered in subsequent rulemakings. As part of the future notice addressing addition of methanol to our list of MSAT, we will also evaluate possible controls in accordance with section 202(l)(2) as appropriate. In the notice of proposed rulemaking we compared lists of emitted compounds to four lists of toxic air pollutants to confirm that our MSAT list was reasonable. The four lists of toxic air pollutants we used were: the Clean Air Act (CAA) Section 112(b) list of hazardous air pollutants; California EPA (CalEPA) list of toxic air contaminants (TAC); U.S. Department of Health and Human Service Agency for Toxic Substances and Disease Registry (ATSDR) list of Minimal Risk Levels (MRLs); and International Agency for Research on Cancer (IARC) monographs on cancer. Comparing these four lists against the emissions speciation studies and databases, we identified two additional compounds not included on our list of MSATs—propionaldehyde and 2,2,4-trimethylpentane. Comments we received on these compounds suggested either that (1) further study was needed to determine the potential for adverse health effects or that (2) both compounds should be added to the list of MSATs based on their presence in the CAA section 112(b) HAP list, or due to the presence of these compounds on the emissions lists. At this time EPA is not including propionaldehyde or 2,2,4-trimethylpentane in the list of MSATs because we do not have an Agency consensus view as expressed on IRIS regarding the potential adverse health effects associated with exposure to these pollutants. EPA assessments of these compounds have been proposed and we will use all currently available information to reassess the possible inclusion of these compounds in the list of MSATs when we evaluate whether additional controls are appropriate in 2003. III. How Are Motor Vehicle Emission Control Programs Reducing MSAT Emissions? In the previous section we identified the 21 MSATs. We now turn to an evaluation of how our various mobile source control programs will affect the inventories of these air toxics. The data and information available on emissions of these 21 MSATs vary considerably. While we have baseline inventory data for all of the MSATs except naphthalene, we do not have inventory projections for all of them. Therefore, we are examining the projected impacts of our current and proposed mobile source control programs by groupings of air toxics. We do have specific projections of future emissions for five gaseous toxics (benzene, formaldehyde, 1,3-butadiene, acetaldehyde, MTBE) and for diesel PM (as the surrogate for DPM + DEOG) and we present these in this section. We do not have emissions projections for the remaining gaseous toxics (acrolein, POM, styrene, toluene, xylene, ethylbenzene, naphthalene, and n-hexane) but, because these compounds are part of VOCs, we believe it is reasonable to utilize VOC emissions inventory projections to estimate the expected impact of our control programs on these other gaseous MSATs. Finally, we also do not have emissions inventory projections for the metals on the MSAT list (arsenic compounds, chromium compounds, mercury compounds, nickel compounds, manganese compounds, and lead compounds) or for dioxins/furans. While metal emissions and dioxin/furans emissions are associated with particles and it is possible that some of these compounds track PM emissions to some extent, we do not have good data on these relationships. Therefore, we are not presenting emission projections for these compounds in this action. We believe this is reasonable because the mobile source contribution to metals inventories is small and comes primarily from engine wear and impurities in engine oil, or from fuel additives. As we describe in the following discussion, there have been and will continue to be significant reductions in MSAT emissions as a result of our mobile source regulations. By 2020, we project on-highway emission control programs (up to and including our Tier 2 control program and our proposed 2007 heavy-duty engine rule) will reduce benzene emissions by 73 percent, formaldehyde emissions by 76 percent, 1,3-butadiene emissions by 72 percent, and acetaldehyde emissions by 67 percent from 1990 levels. Under these same controls we project on-highway diesel PM emissions will be reduced by 94 percent by 2020, as compared with 1990 levels. Nonroad engines and equipment also contribute substantially to levels of MSAT emissions and have only in recent years been subject to emission standards. Since nonroad engines are not subject to the same stringent controls as on-highway vehicles, the reductions from these sources are more moderate than those for on-highway sources. The discussion in this section consists of two parts. First, we describe current inventories of MSAT emissions. Next, we describe how our on-highway emission control programs will reduce these inventories. Interested readers should refer to Chapter 4 of our TSD for more detailed information about the methodology we used to compile these inventories and the results of our analysis. We consider the impacts of our nonroad engine control programs on MSAT emissions in Section VI of this preamble. A. Baseline Inventories We developed inventory estimates for several gaseous MSATs (acetaldehyde, benzene, 1,3-butadiene, formaldehyde, MTBE) and also for diesel PM as part of the 1999 study, “Analysis of the Impacts of Control Programs on Motor Vehicle Toxic Emissions and Exposure in Urban Areas and Nationwide,” (hereafter referred to as the 1999 EPA Motor Vehicle Air Toxics Study, or the 1999 Study). 8 The pollutants examined in the 1999 Study were chosen because we had adequate data to perform a rigorous modeling analysis for those pollutants. The 1999 Study examined the impact of a variety of parameters including fuel properties, emission control technologies, and type of in-use operation on the 1990 and 1996 emissions inventories for these six pollutants. The 1990 baseline represents estimated emissions before any of the programs added by the1990 Clean Air Act Amendments were implemented. The 1996 estimates reflect toxics emissions with some of the new Clean Air Act programs in place, such as Phase 1 of the RFG program. Note that since completion of the 1999 Study, we have updated our estimates of diesel PM emissions and our estimates of toxics emissions from heavy-engines (as part of improvements made with regard to heavy-duty engine modeling). Our updated baseline toxics inventory estimates are presented in Table III-1. It should also be noted that these estimates are only for on-highway vehicles. 8 Analysis of the Impacts of Control Programs on Motor Vehicles Toxics Emissions and Exposure in Urban Areas and Nationwide (Volumes 1 and 2), November 1999. EPA420-R-99-029/030. This report can be accessed at http://www.epa.gov/otaq/toxics.htm. Table III-1.—Annual Emissions From On-Highway Vehicles for Selected Air Pollutants [Short tons per year] a Compound 1990 Emissions 1996 Emissions b 1,3-Butadiene 36,000 24,000 Acetaldehyde 41,000 31,000 Benzene 257,000 171,000 Formaldehyde 139,000 93,000 Diesel PM 235,000 c 182,000 MTBE 55,000 67,000 a In this notice we report emissions in terms of short tons as opposed to metric tons. b The 1996 estimates are based on updated inventories taking into consideration the proposed 2007 and later model year heavy-duty engine standards. c For 1990, we used diesel PM estimates from EPA's Trends Report. The 1996 National Toxics Inventory (NTI) prepared in connection with the Agency's NATA activities also contains emission estimates for 1,3-butadiene, acetaldehyde, benzene, formaldehyde and MTBE. The 1996 NTI emission estimates for these compounds differ slightly from those generated in the 1999 EPA Motor Vehicle Air Toxics Study, due to revisions made to the NTI based on updated vehicle miles traveled (VMT) information provided by a number of states, minor changes to the emissions model used (the MOBTOX model), and revised heavy-duty information. Since DPM + DEOG is not included on the list of 112(b) hazardous air pollutants, which is the focus of the 1996 NTI, DPM + DEOG estimates were not compiled in the 1996 NTI. The 1996 NTI also contains 1996 emissions estimates for several other MSATs, and includes data for nonroad 9 as well as on-highway sources. We present these data in Table III-2. We also indicate the on-highway and nonroad percentages of the national inventories for these MSATs (the total national inventories include emissions from on-highway and nonroad mobile sources, major and area stationary sources, and other sources such as forest fires). Between the 1999 EPA Motor Vehicle Air Toxics Study and the 1996 NTI, we have baseline inventory data for all of the 21 MSATs except naphthalene. 10 (For DPM + DEOG, we do not have inventory data on the DEOG portion. For this analysis, we are using DPM as a surrogate for DPM + DEOG.) While good baseline data exist for many of the MSATs, they do not exist for all. As noted earlier, we plan to conduct additional research in coordination with other toxics research activities that are ongoing in the Agency to improve our characterization of toxics emission from mobile sources. 9 The nonroad inventory in the 1996 NTI includes emissions data for aircraft, commercial marine vessel, locomotives, and other nonroad engines. Note that under the Clean Air Act definition, nonroad vehicles do not include aircraft. For convenience, in this action the term “nonroad” will include aircraft except where otherwise noted. It should be noted that the NONROAD model, on which the estimates for nonroad engines other than locomotive, commercial marine vessels, and aircraft are based, is still draft, and the emissions estimates based on this model are subject to change. 10 Naphthalene emissions are not reported in the 1996 NTI separately from 16-PAH. See Chapter 3 of the TSD for the explanation of the linkage between diesel exhaust and diesel PM. Table III-2.—1996 On-Highway and Nonroad Emission Inventories of Some MSATs From the 1996 NTI [Short tons] Compound On-Highway Tons Percent of Total National Emmissions Nonroad Tons Percent of Total National Emmissions Mobile Sources Tons Percent of Total National Emmissions 1,3-Butadiene a 23,500 42 9,900 18 33,400 60 Acetaldehyde a 28,700 29 40,800 41 69,500 70 Acrolein a 5,000 16 7,400 23 12,400 39 Arsenic Compounds a 0.25 0.06 2.01 0.51 2.26 0.57 Benzene a 168,200 48 98,700 28 266,900 76 Chromium Compounds a 14 1.2 35 3 49 4.2 Dioxins/Furans a, b 0.0001 0.2 N.A. N.A. 0.0001 0.2 Ethylbenzene 80,800 47 62,200 37 143,000 84 Formaldehyde a 83,000 24 86,400 25 169,400 49 Lead Compounds a 19 0.8 546 21.8 565 22.6 Manganese Compounds a 5.8 0.2 35.5 1.3 41.3 1.5 Mercury Compounds a 0.2 0.1 6.6 4.1 6.8 4.2 MTBE 65,100 47 53,900 39 119,000 86 n-Hexane 63,300 26 43,600 18 106,600 44 Naphthalene N.A. N.A. N.A. N.A. N.A. N.A. Nickel Compounds a 10.7 0.9 92.8 7.6 103.5 8.5 POM (as sum of 7 PAH) a 42.0 4 19.3 2 61.3 6 Styrene 16,300 33 3,500 7 19,800 40 Toluene 549,900 51 252,200 23 802,100 74 Xylene 311,000 43 258,400 36 569,400 79 a These compounds are also on the list of urban HAPs for the Integrated Urban Air Toxics Strategy. b Mass given in tons of TEQ (toxic equivalency quotient). The EPA Office of Research and Development (ORD) has recently developed an inventory for dioxin and dioxin-like compounds using different methods than those used in the 1996 NTI. For 1995, the EPA-ORD estimate of on-highway emissions of dioxin compounds is 0.00005 tons TEQ, comprising 1.5 percent of the national inventory in that year. (The TEQ rates the toxicity of each dioxin and furan relative to that of 2,3,7,8-TCDD, which is assigned a TEQ of 1.0.) The above inventory data reflect certain interesting characteristics of mobile source air toxics emissions. First, mobile sources account for the majority of the national inventory of three of the gaseous MSATs that are included on the urban HAP list. These three are 1,3-butadiene (60 percent), acetaldehyde (70 percent), and benzene (76 percent). Mobile sources account for 39 percent of the national inventory of acrolein, and 49 percent of the national inventory of formaldehyde, two other gaseous urban HAPs. All of these MSATs are formed as part of the combustion process except for benzene, which is also released through evaporative emissions from gasoline. Second, with regard to the other MSATs that are included on the urban HAP list, the mobile source contribution generally is small (arsenic compounds, chromium compounds, manganese compounds, mercury compounds, nickel compounds, POM, and dioxins/furans). The sole exception is lead compounds. Mobile sources contribute 23 percent to national inventories of lead compound emissions, due primarily to nonroad sources and, more specifically, to the use of a lead-additive package used to boost the octane of aviation gasoline. 11 The mobile source contribution to the other metals on the urban HAP list comes primarily from engine wear, some fuel additives, or impurities in engine oil. 11 Aviation gasoline is used by a relatively small number of aircraft, those with piston engines, which are generally used for personal transportation, sightseeing, crop dusting, and similar activities. With regard to the gaseous MSATs that are not included on the urban HAP list (ethylbenzene, MTBE, n-hexane, toluene, and xylene), mobile source contributions are high because of the presence of these compounds in gasoline. In addition, mobile sources account for almost all diesel PM emissions. A limited number of stationary sources, such as large generators, do operate on diesel fuel. Because there are relatively few stationary sources that operate on diesel fuel, we believe that diesel PM from stationary sources is relatively small compared to diesel PM from mobile sources. (However, for this analysis we have not generated an estimate of diesel PM from stationary sources.) As shown in Table III-1, above, we estimate that 1996 on-highway diesel PM emissions are approximately 182,000 tons. We estimate that 1996 nonroad diesel PM emissions are approximately 346,000 tons, as discussed in Section VI of this notice. 12 12 It should be noted that the nonroad diesel PM emissions estimate is based on the draft NONROAD model and is subject to change. B. Impacts of Motor Vehicle Emission Controls on Emission Inventories 1. Description of Emission Control Programs Many of the programs that we have put in place since the passage of the 1990 Clean Air Act Amendments to achieve attainment of the National Ambient Air Quality Standards (NAAQS) for ozone, PM and CO have also reduced MSAT emissions. For example, measures to control hydrocarbons from motor vehicles are also effective in controlling gaseous toxics. In addition, certain programs address air toxics directly, such as the RFG program and the gasoline lead phase-out. In this section we briefly describe several categories of mobile source emission control measures that have helped reduce inventories of these harmful compounds. These programs include: • More stringent vehicle standards and test procedures. The 1990 Clean Air Act Amendments set specific emission standards for hydrocarbons and for PM. Air toxics are present in both of these pollutant categories. As vehicle manufacturers develop technologies to comply with the hydrocarbon and particulate standards ( e.g., more efficient catalytic converters), we expect air toxics to be reduced as well. Since 1990, we have developed a number of programs to address exhaust and evaporative hydrocarbon emissions and PM emissions. Some of the key programs are the Tier 1 and NLEV standards for light-duty vehicles and trucks; enhanced evaporative emissions standards; the supplemental federal test procedures (SFTP); urban bus standards; and heavy-duty diesel and gasoline standards for the 2004/2005 time frame. • Recent motor vehicle/fuel control initiatives. Two of our recent initiatives to control emissions from motor vehicles and their fuels are the Tier 2 control program and our proposed 2007 heavy-duty engine rule. Together these two initiatives define a set of comprehensive standards for light-duty and heavy-duty motor vehicles and their fuels. In both of these initiatives, we treat vehicles and fuels as a system. The Tier 2 control program establishes stringent tailpipe and evaporative emission standards for light-duty vehicles and a reduction in sulfur levels in gasoline fuel beginning in 2004. The proposed 2007 heavy-duty engine rule would establish stringent exhaust emission standards for heavy-duty engines and vehicles for the 2007 model year as well as reductions in diesel fuel sulfur levels starting in 2006. • Limits on gasoline volatility. Volatility is a measure of how easily a liquid evaporates. As described earlier, some toxics such as benzene are present in gasoline and get into the air when gasoline evaporates. We imposed limits on gasoline volatility in the early 1990s to control evaporative emissions of both hydrocarbon and toxic compounds (most air toxics are hydrocarbons, so programs designed to reduce hydrocarbon emissions also reduce air toxics). • Reformulated gasoline. The 1990 Clean Air Act Amendments required reformulated gasoline to be introduced in the nation's most polluted cities beginning in 1995. From 1995 through 1999, these gasolines were required to provide a minimum 16.5 percent reduction in air toxics emissions over typical 1990 gasolines, increasing to a 21.5 percent minimum reduction beginning in the year 2000. The air toxics reductions have been achieved mainly by further reducing gasoline volatility and by reducing the benzene, aromatics, sulfur, and olefin content of the gasoline. • Phase-out of lead in gasoline. One of the first programs to control toxic emissions from motor vehicles was the removal of lead from gasoline. Beginning in the mid-1970s, unleaded gasoline was phased in to replace leaded gasoline. The phase-out of leaded gasoline was completed January 1, 1996 when lead was banned from motor vehicle gasoline. The removal of lead from gasoline has essentially eliminated on-highway mobile source emissions of this highly toxic substance. • Ensuring emissions are controlled throughout the vehicle's life. Many of our vehicle standards require certification of new engines and vehicles, but ensuring continued performance of emission controls can be difficult. The Clean Air Act establishes several programs to make sure vehicle emission controls are functioning properly in actual use. These programs include requirements for periodic emission inspections (I/M, or inspection and maintenance programs) and for computerized on-board diagnostic systems that alert drivers and mechanics to malfunctioning emission controls. We encourage the interested reader to refer to Chapter 1 of our TSD for more detailed information about these programs. 2. Emission Reductions From Control Programs We expect the mobile source emissions control programs described above to have beneficial impacts on national inventories of MSATs. The remainder of this section summarizes our MSAT inventory projections. First, we present an overview of the methodologies used to project future emissions inventories. Next, we present the results of our inventory projections. We encourage interested readers to refer to Chapter 4 of our TSD for a more detailed discussion of these projections and how we developed them. The inventory projections in this section are for on-highway vehicles only. Projections of nonroad MSAT emissions are included in Section VI of this preamble. a. Overview of Inventory Sources We developed inventory projections that reflect our current and proposed control programs, described above, for five gaseous MSATs, for VOC, and for diesel PM for the years 2007 and 2020. The inventory projections for the five gaseous toxics are based on the 1999 EPA Motor Vehicle Air Toxics Study, updated to incorporate a variety of new information on on-highway vehicles. The 1999 Study estimated on-highway motor vehicle air toxics emissions for ten urban areas (Atlanta, Chicago, Denver, Houston, Minneapolis, New York City, Philadelphia, Phoenix, Spokane, and St. Louis) and 16 geographic regions. These areas were selected to reflect the range of potential fuels, temperatures, and I/M programs observed in the United States. Every county in the country was then “mapped” to one of these modeled areas or regions. Mapping was done based on a combination of geographic proximity, I/M program, and fuel control programs. The estimation methodology used in the 1999 Study was similar to that used in our original 1993 Motor Vehicle Related Air Toxics Study. In our approach, the MOBILE model is used to generate total organic gas (TOG) emissions from on-highway motor vehicles by vehicle class and model year. Toxics fractions, developed as a percentage of the toxic compound of interest contained in TOG emissions, are then applied to the MOBILE-based TOG emission rates (reported in grams per mile) to arrive at toxics emission rates (reported in grams per mile or milligrams per mile). For light-duty vehicles, information developed for the Complex Model was used to develop these relationships. These toxics fractions are developed as a function of vehicle class ( e.g., light-duty, heavy-duty), fuel type ( e.g., gasoline or diesel), fuel composition, and technology type ( e.g., non-catalyst, catalyst). We do not have detailed emissions data for gaseous MSATs other than the five gaseous MSATs examined in the 1999 Study. However, we expect the trend for other gaseous MSATs, including acrolein, POM, styrene, xylene, toluene, ethylbenzene, naphthalene, and n-hexane, to follow that of VOC, since all of these compounds are VOCs. We recognize that some gaseous MSATs may not decrease at the same rate as VOCs overall. Without having more detailed emission data for each of the MSATs, however, we are unable to project how those rates may differ. Because we do not have emissions data for DEOG, we are using diesel PM as the surrogate for the MSAT listed as DPM and DEOG. Where we have data regarding specific constituents in the diesel exhaust organic gas phase we present that information. Our VOC and diesel PM emission estimates are derived from several sources. The 1996 and later values are based on updated modeling that factors in the impact of the proposed 2007 heavy duty engine standards. The 1990 VOC emission estimate is based on the 1999 EPA Motor Vehicle Air Toxics Study, 13 and the 1990 diesel PM is from EPA's Trends Report. 14 13 The analysis methodology is described in a memorandum from Meredith Weatherby, Eastern Research Group, to Rich Cook, EPA, entitled “Estimating of 1990 VOC and TOG Emissions” in EPA Air Docket A-2000-12. 14 EPA, 2000. National Air Pollution Emission Trends, 1900-1998 (March 2000). Office of Air Quality Planning and Standards, Research Triangle Park, NC. Report No. 454/R-00-002. We are not reporting inventory trends for the metals on our list of MSATs (arsenic compounds, chromium compounds, mercury compounds, nickel compounds, manganese compounds, and lead compounds) or for dioxins/furans because we do not have good data on these relationships at this time. Metals in mobile source exhaust can come from fuel, fuel additives, engine oil, engine oil additives, or engine wear. Formation of dioxin and furans requires a source of chlorine. Thus, while metal emissions and dioxin/furan emissions are associated with particles and it is possible that some of these compounds track PM emissions to some extent, there are a number of other factors that contribute to emissions, and we do not have good data on these relationships. We did receive one comment regarding inputs to the emission inventory modeling performed for the NPRM. The National Petrochemical and Refiners Association (NPRA) commented that the vehicle miles traveled (VMT) growth rates for heavy-duty vehicles, which were based on 1998 estimates from the Energy Information Agency (EIA), were too high. In support of their comments, NPRA submitted EIA's 1999 estimates which were lower than those from 1998 used by EPA. For the inventory projections contained in today's action, we have retained the same growth rates used in the NPRM analysis. Based on discussions with EIA, we believe the 2000 growth estimates will be higher than both the 1999 estimates NPRA referenced and the 1998 estimates we used in the NPRM analysis. 15 However, because the final 2000 numbers are not yet available from EIA, we are retaining the use of the growth rates used in the NPRM as a more reasonable estimate than the 1999 growth estimates. 15 “Early Release of the Annual Energy Outlook 2001,” available at www.eia.doe.gov/oaif/aeo/earlyrelease/index.html, Energy Information Administration, downloaded from EIA web site on December 12, 2000. b. Emission Reductions Table III-3 presents the annual emission projections for on-highway vehicles for five gaseous toxics, VOC, and diesel PM with our current on-highway control programs and the proposed 2007 and later model year heavy-duty engine standards. The 1996 inventories presented in Table III-3 are slightly higher than the 1996 inventories presented in Table III-2 because the estimates of heavy-duty vehicle VMT have been updated and improved since the VMT estimates for the 1996 NTI were prepared. Table III-3.—Annual Emmissions Inventories From On-Highway Vehicles a [Thousand short tons per year] Compound 1990 1996 2007 2020 1,3 Butadiene 36 24 12 10 Acetaldehyde 41 31 17 13 Benzene 257 171 89 68 Formaldehyde 139 93 43 34 Diesel PM 235 182 85 15 MTBE b 55 67 26 18 VOC 7,585 4,933 3,028 2,153 a Includes the impact of our current on-highway control programs and the proposed 2007 and later model year heavy-duty engine standards. b These estimates do not include consideration of EPA's examination of options to phase down or otherwise control the use of MTBE under the Toxic Substances Control Act, or legislative authority that EPA has asked Congress to provide the Agency to address MTBE use in gasoline. Table III-4 summarizes the percent reductions we expect in on-highway emissions of gaseous MSATs, VOC, and diesel PM from 1990 and 1996 levels in 2007 and 2020 as a result of our current on-highway control programs and the proposed 2007 and later model year heavy-duty engine standards. Table III-4.—Reductions in On-Highway Vehicle Emissions a Compound Reduction in 2007 From 1990 (Percent) From 1996 (Percent) Reduction in 2020 From 1990 (Percent) From 1996 (Percent) 1,3 Butadiene 67 50 72 57 Acetaldehyde 58 46 67 57 Benzene 65 48 73 60 Formaldehyde 69 54 76 64 Diesel PM 64 53 94 92 MTBE b 52 61 67 73 VOC 60 39 72 56 a Includes the impact of our current on-highway control programs and the proposed 2007 and later model year heavy-duty engine standards. b These estimates do not include consideration of EPA's examination of options to phase down or otherwise control the use of MTBE under the Toxic Substances Control Act, or legislative authority that EPA has asked Congress to provide the Agency to address MTBE use in gasoline. The results of this analysis show that on-highway emissions of the five gaseous MSATs examined are expected to decline by 67 to 76 percent by 2020 from 1990 levels with our existing and proposed control programs. For some gaseous MSATs, the reductions are even greater. Likewise, VOC inventories from on-highway vehicles are projected to decrease by 72 percent between 1990 and 2020 and we assume that other gaseous toxics would decrease by approximately 72 percent as well. Finally, diesel PM emissions are projected to decline by 94 percent by 2020 from 1990 levels. IV. Evaluation of Additional Motor Vehicle-Based Controls We are not establishing new standards for motor vehicles in this rulemaking to control MSAT emissions. Based on the information available to the Agency at this time, we have determined that our proposed and current control programs for VOC and diesel PM emissions from motor vehicles will achieve the greatest degree of MSAT control that is feasible when cost and other relevant factors are considered. This section summarizes our rationale for this determination, including the relationship between EPA's vehicle-based control programs and the control of MSATs (especially for those programs established after the 1990 Clean Air Act Amendments), the impact of our most recent efforts to control VOCs, and the possibility of additional control. The Technical Support Document contains additional information. It is important to note that while we are not adopting new vehicle-based controls in this rulemaking, we will continue to consider the need for, and feasibility of, vehicle-based controls in the future and as part of our Technical Analysis Plan. As we have in the past, we will also continue to look for opportunities to control MSAT emissions in conjunction with other pollutants ( e.g., NO X , SO 2 , VOC). Most of the vehicle-based comments focused on these types of controls. These comments are addressed in the Response To Comments document. A. MSATs and Motor Vehicle-Based Controls The majority of gaseous MSATs are hydrocarbons that are primarily the result of incomplete combustion of petroleum fuels. Since a small amount of raw fuel passes through the engine unburned, MSATs present in the fuel are also emitted in the exhaust. In either case, the technologies used to reduce exhaust hydrocarbons also reduce the hydrocarbon species listed as MSATs. This is true whether control is achieved through engine or component modifications, add-on devices, or the use of aftertreatment devices such as oxidation or three-way catalysts. We are not aware of vehicle or engine technologies that selectively reduce MSATs without reducing other hydrocarbons to a similar degree. The other major source of hydrocarbon emissions from motor vehicles is fuel vapors. These emissions occur when components of the liquid fuel (gasoline or diesel) evaporate when on board the vehicle. The emissions are normally separated into refueling emissions and evaporative emissions (hot soak, diurnal, and running losses). The nature and amount of potential MSATs associated with fuel vapors depend primarily on the fuel composition and the temperatures involved. Gasoline is volatile and evaporates at normal ambient temperatures, while diesel fuel is relatively non-volatile. Thus evaporative emissions are only a significant issue for gasoline-fueled vehicles (or vehicles using volatile alternative fuels). Evaporative and refueling emissions are controlled by eliminating sources of potential liquid and vapor leaks within the vehicle fuel system and venting any vapors to an activated carbon canister or similar device. Activated carbon effectively adsorbs most hydrocarbon compounds, including the common evaporative-related MSATs. Particulate matter emissions from motor vehicles are primarily composed of partially burned carbon and hydrocarbons from the fuel and engine oil, and to a lesser degree, metals and other inorganic compounds from contaminants or additives in the fuel or engine oil, or products of engine wear in the oil. Since our PM exhaust emission standards apply without regard to the source of the PM, manufacturers must account for all of these emissions. Manufacturers have significantly reduced PM emissions associated with unburned fuel and engine oil through combustion system and engine modifications. In some cases, they have also achieved reductions using aftertreatment. To understand the relationship between the Agency's current emission control program for on-highway vehicles and the control of MSATs, it is important to first understand the structure and scope of our current emission control programs. EPA's emission control program for on-highway vehicles has historically been divided into two broad vehicle/engine categories that we regulate: “light-duty” (vehicles 8,500 pounds gross vehicle weight rating (GVWR) or less) and “heavy-duty” (vehicles above 8,500 pounds GVWR). 16 Within these light-duty and heavy-duty categories, we further distinguish vehicles and sometimes establish different emission limits based on vehicle size or other factors. 16 EPA recently created the new category of “medium-duty passenger vehicles” (MDPVs) that includes passenger vehicles 8,500-10,000 pounds GVWR. B. Vehicle-Based Standards To Reduce MSATs From Light-Duty Vehicles Before we began regulating automobile exhaust, vehicles typically emitted more than 9 grams per mile (gpm) HC in exhaust emissions. Our HC emission standards in the 1970s and 1980s cut these levels by more than an order of magnitude, to 0.41 gpm in 1980. In 1991, we finalized Tier 1 controls for light-duty vehicles and light-duty trucks to be phased in from 1994 to 1996 (56 FR 25724). In 1998, we developed an innovative, voluntary nationwide program to make new cars, called National Low Emission Vehicles (NLEV), significantly cleaner than Tier 1 cars (63 FR 926). The NLEV program went into effect in the Northeast states in 1999 and will go into effect in the rest of the country in 2001. Table IV-1 illustrates the declining HC exhaust standards through the NLEV program. 17 Also shown in the table are the number of miles for which the standards apply, which has increased with time. Thus manufacturers need to make their emission control systems more durable and reliable over a longer period of time. 17 Our programs achieve VOC reductions through standards that limit HC, NMHC, or NMOG. Table IV-1.—Hydrocarbon (HC) Exhaust Emission Standards for Light-Duty Vehicles [GPM] Year 1972 1975 1980 1994 2001 Standard 3.4 1.5 0.41 a 0.31 b 0.09 Applicability (Miles) 50,000 50,000 50,000 100,000 120,000 a The 1994 standard is a nonmethane hydrocarbon (NMHC) standard. b The 2001 standard is a nonmethane organic gas (NMOG) standard. This standard will be replaced by the new multi-level Tier 2 NMOG standards, but the average standard level should remain at approximately 0.09 gpm. In December 1999, the Agency finalized the Tier 2/sulfur rule establishing light-duty requirements that will be phased-in beginning with the 2004 model year. These requirements phase-in a set of tailpipe emission standards that will, for the first time, apply the same standards to passenger cars, light-duty trucks (LDTs), and larger passenger vehicles. To enable the very clean Tier 2 vehicle emission control technology to be introduced and to maintain its effectiveness, nationwide gasoline sulfur requirements were also put into place. The Tier 2 program begins in 2004 for passenger cars and light LDTs (LDTs up to 6,000 pounds GVWR), while an interim program begins in 2004 for heavy LDTs (LDTs over 6,000 pounds GVWR). For heavy LDTs and MDPVs (medium-duty passenger vehicles), the Tier 2 standards will be phased in beginning in 2008, with full compliance in 2009. Thus, when fully implemented, all vehicles designed for passenger use will have to meet the stringent new emission standards. The Tier 2 program is designed to focus on reducing the ozone and particulate matter air quality impact of these vehicles. Ozone reductions will be achieved through control of nitrogen oxides and non-methane hydrocarbons. As discussed above, it is the control of HC through the NMOG standards that results in the control of the gaseous toxics. The Tier 2 rule also established stringent PM standards. Control of PM emissions will occur through reductions in gasoline sulfur and the use of aftertreatment for diesel vehicles. Because all Tier 2 standards are fuel neutral, the PM standards apply to both gasoline and diesel vehicles. The Tier 2 standards will reduce new vehicle NO X levels to an average of 0.07 grams per mile. The NMOG standards vary depending on which of the various “bins” (i.e., certification categories) the manufacturers choose to use in complying with the average NO X standard. However, we expect significant reductions in NMOG emissions from these vehicles as a result of the more stringent NMOG standards in the bins and the need to select bins to meet the NO X average. When fully phased-in, we expect fleet average NMOG levels at or below the 0.09 g/mi level. This will represent a 99 percent reduction from uncontrolled pre-1970 levels. Since these controls should be at least as effective at reducing MSATs, these standards should also reduce MSATs to a similar extent from uncontrolled levels. The Tier 2 rule also finalized formaldehyde standards that harmonize federal standards with the California's LEV II program. Section 202(l)(2) of the Clean Air Act instructs the Agency to promulgate regulations that, at a minimum, apply to emissions of benzene and formaldehyde. We believe that the shift to a toxics emissions performance requirement will limit emissions of these two pollutants. In response to comments, we also considered setting more stringent vehicle-based formaldehyde standards in this FRM. However, since we are not aware of any technology that could specifically reduce formaldehyde emissions, we have no confidence that more stringent vehicle or engine formaldehyde standards would be feasible. Nevertheless, we remain confident that the combination of our Toxics Performance Standard, Tier 2 formaldehyde standards and Tier 2 NMOG standards described above will achieve significant reductions in formaldehyde emissions. In order to meet strict Tier 2 standards on a fleet-wide average, manufacturers will have to use a combination of sophisticated calibration changes and emission system hardware modifications to increase and maintain high control system efficiency. They will be challenged to maintain tight air-fuel control and improved catalyst performance, especially achieving better catalyst thermal management. Minimizing the time necessary for the catalyst to reach its operating temperature will be especially critical, since the vast majority of emissions occur in the minute or less which passes before the catalyst “lights off.” Many manufacturers are going to have to depend more on the precious metal palladium for oxidation of NMOG and CO emissions, as well as the reduction of NO X . Palladium is more tolerant to high temperatures and will enable manufacturers to increase catalyst efficiency in a broad range of in-use conditions. These technologies will be highly effective at reducing MSATs, including benzene and formaldehyde. Our existing regulations also contain test procedures to measure evaporative hydrocarbon emissions during a simulated parking event (diurnal emissions) and immediately following a drive (hot soak emissions). In 1993, we finalized more stringent evaporative emission test procedures which apply to light-duty and heavy-duty gasoline vehicles. That rule also addressed fuel spitback and spillage during refueling. These procedures were fully phased in by 1999 (58 FR 16002). The Tier 2 rule included even more stringent requirements. The Tier 2 evaporative standards represent, for most vehicles, more than a 50-percent reduction in diurnal plus hot soak standards from those that will be in effect in the years immediately preceding Tier 2 implementation. These standards should achieve similar reductions in gaseous MSATs. In fact, since the activated carbon used to capture evaporative emissions preferentially adsorbs larger organic molecules, these controls may achieve a greater degree of control of MSATs, which are generally larger and heavier than many other gasoline components. Under these requirements, it is likely that manufacturers will also need to upgrade materials and both increase the reliability of fuel/vapor hose connections and fittings and reduce the number used in the system. We have also finalized on-board refueling vapor recovery (ORVR) requirements for light-duty gasoline vehicles (59 FR 16262, April 6, 1994). ORVR is a nationwide program for capturing refueling emissions by collecting vapors from the vehicle gas tank and storing them in the vehicle during refueling. The fuel vapors are then purged into the engine air intake to be burned while the vehicle is being driven. Taken as a whole, the Tier 2 program presents the manufacturers with significant challenges in the coming years. It will require the use of hardware and emission control techniques and strategies not used in the fleet today. Bringing essentially all passenger vehicles under the same emission control program regardless of their size, weight, and application is a major engineering challenge. While there may be other prototype technologies on the horizon which could potentially reduce cold-start emissions and therefore air toxics, we have concluded that it would not be appropriate to set tighter standards in this FRM based on these prototype technologies. We are not convinced that these technologies would be feasible and cost effective on a fleet-wide basis in the near future. This is discussed in more detail in Chapter 6 of the TSD. C. Vehicle-Based Standards To Reduce MSATs From Heavy-Duty Engines Table IV-2 summarizes the hydrocarbon and PM standards for heavy-duty engines. Also shown in the table are estimates of emission rates from uncontrolled engines. In addition, the standards in our recently proposed 2007 heavy-duty rulemaking are also shown in the table. 18 18 65 FR 35429, June 2, 2000. Table IV-2.—HC and PM Exhaust Emissions and Standards for Heavy-Duty Engines Gasoline (Otto-Cycle) Exhaust HC Diesel Exhaust HC Exhaust PM Uncontrolled Emissions 10-13 g/bhp-hr 4 g/bhp-hr 0.7 g/bhp-hr. Current Standards 1.1 g/bhp-hr a 1.3 g/bhp-hr 0.10 g/bhp-hr. 2004/5 Standards 0.25 g/bhp-hr b 0.4 g/bhp-hr c 0.10 g/bhp-hr. Proposed 2007 Standards 0.14 g/bhp-hr 0.14 g/bhp-hr 0.01 g/bhp-hr. a Current standard is 1.9 g/bhp-hr for Otto-cycle vehicles over 14,000 GVWR. b Standard was set as a 2005 NMHC+NO X standard; level shown is estimated equivalent NMHC standard. c Standard is a 2004 NMHC+NO X standard; level shown is estimated equivalent NMHC standard. With regard to exhaust emission standards, the proposed 2007 heavy-duty engine standards would reduce hydrocarbon emissions to levels approaching 0.1 g/bhp-hr for both gasoline and diesel. This would result in a significant reduction even when compared to the 2004 standards. Similarly, the new exhaust PM standard for heavy-duty diesel engines is stringent. This standard (0.01 g/bhp-hr) is a 90-percent reduction from current standards which are currently being achieved with significant combustion chamber and engine modifications. Achieving a 0.01 g/bhp-hr standard will require the use of catalyzed PM traps. This technology will also result in HC emission reductions. It is further worth noting that the proposed 2007 standards include provisions for a closed crankcase for turbocharged diesel engines. Crankcase emissions from these engines are a significant source of MSATs (PM and hydrocarbons) that has previously remained uncontrolled. For chassis-certified gasoline-powered heavy-duty vehicles, EPA proposed that beginning in 2007 they meet exhaust hydrocarbon standards of similar stringency to those discussed above for Tier 2. These include hydrocarbon standards of 0.195 g/mi for vehicles of 8,500-10,000 lbs GVWR and 0.23 g/mi for vehicles of 10,001-14,000 lbs GVWR. Fuel quality changes will enable gasoline and diesel-powered vehicles/engines to meet the more stringent standards over their full life. As part of the Tier 2 rule, EPA promulgated provisions limiting gasoline sulfur levels to 30 ppm average and 80 ppm cap. This program phases in beginning in 2004, and will enable a new generation of vehicle emission control for heavy-duty gasoline vehicles and also improve the emission performance of the current fleet. Sulfur is a fuel contaminant, and controlling sulfur will also reduce sulfate PM emissions. The 2007 heavy-duty proposal mentioned above also includes provisions that would greatly reduce the sulfur content of current on-highway diesel fuel. Not only would this reduction enable the emission control technology now under development, but it would also reduce sulfate PM emissions . We have recently extended our onboard diagnostic (OBD) requirements to heavy-duty gasoline engines up to 14,000 pounds GVWR (65 FR 59896, October 6, 2000). These OBD provisions require that vehicle manufacturers install dashboard indicators that alert drivers to the need for emission-related maintenance, and electronic monitors that store codes in the vehicle's computer to assist mechanics in the diagnosis and repair of the malfunction. As some of the commenters noted, requiring that all highway vehicles incorporate these OBD systems will ensure good control of in-use emissions, including MSAT emissions. We are in the process of developing a proposal that would address OBD provisions for all other heavy-duty vehicles. We have also proposed in the 2007 rulemaking more stringent evaporative standards, which will force even further refinements in fuel/vapor systems. Beginning in 2005, onboard refueling vapor control will be required for all heavy-duty gasoline-powered vehicles (65 FR 59896, October 6, 2000). This would reduce emissions by 95 percent from current uncontrolled levels. In addition, as part of the proposed 2007 rulemaking, EPA proposed to reduce evaporative emission standards by 50 percent over current standards. Both refueling controls and further evaporative controls will reduce evaporative emissions of air toxics from heavy-duty vehicles even further. The proposed rulemaking for 2007 heavy-duty engine and vehicle standards contains extensive analysis and discussion of the technological feasibility of potential HC and PM emission controls for heavy-duty engines. That draft analysis demonstrated EPA's belief at the time of the proposal that those heavy-duty standards would be the greatest degree of emission reduction achievable through the application of technology that will be available considering costs and other relevant factors. EPA believes that the proposed rule to establish 2007 model year standards for heavy-duty diesel engines satisfies the criteria in section 202(a) as well as 202(l)(2) and therefore defers to the technical decisions made in that rulemaking. D. Conclusions Regarding Vehicle-Based Standards We are not establishing new standards for motor vehicles in this rulemaking to control MSAT emissions. We believe our decision in this regard is appropriate given the information currently available. We are also confident that our existing programs (and proposed programs, if finalized) will continue to achieve very significant reductions in MSAT emissions. The Tier 2 program represents a comprehensive, integrated package of exhaust, evaporative, and fuel quality standards. The Tier 2 program will achieve significant reductions in NMHC, NO X , and PM emissions from all light-duty vehicles in the program. These reductions will include reductions in MSATs. Emission control in the Tier 2 program will be based on the widespread implementation of advanced catalyst and related control system technology. The standards are very stringent and will require manufacturers to make full use of nearly all available emission control technologies. To illustrate this point, it is worth noting that about 80 percent of all remaining emissions from a well-maintained Tier 2 vehicle will occur in the first 60 seconds of operation, before the catalyst “lights-off.” Manufacturers will have to optimize both their cold-start strategies and the efficiency of warmed systems to achieve the Tier 2 levels. Compliance with the Tier 2 standards will require the application of emission technology not widely used in the light-duty fleet today and in some cases the use of technological approaches still under development. Based on the information available to the Agency at this time, we believe that the technologies that will be applied to meet the Tier 2 requirements provide the greatest achievable reductions in emissions of air toxics as well, considering costs and other relevant factors. The existing emission control program for heavy-duty engines and vehicles has already achieved major reductions in MSAT emissions . New more stringent emission standards for heavy-duty engines will take effect in 2004 and 2005. We have also proposed a further initiative that would require additional control of heavy-duty vehicle/engine emissions (65 FR 35430, June 2, 2000). This would establish new heavy-duty engine and vehicle emission standards beginning with model year 2007. The 2007 rulemaking is being finalized separately in a broader rulemaking that addresses the complicated implementation issues associated with proposed emission standards. In developing a final rule that would establish these standards, the Agency intends to adopt standards that would result in the greatest achievable reductions in emissions of air toxics as well, considering costs and other relevant factors. We have also made significant progress in the area of in-use operation. To address the malmaintenance issue, we have established OBD requirements for manufacturers (both light-duty and heavy-duty). To address both the malmaintenance and tampering issues, we are working with states to develop and optimize inspection and maintenance (I/M) programs that monitor the emission performance of in-use vehicles. Historically, these programs have relied on tailpipe testing to identify high-emitting vehicles. However, these programs have begun to rely more on the OBD systems to identify the high-emitting vehicles, as well as the cause of the emission problem. We are also investigating ways in which we could encourage the use of new emission controls on older vehicles. As described in the Response to Comments, these are not being finalized in this FRM. V. Evaluation of Additional Fuel-Based Controls The previous section evaluated motor vehicle controls in the context of mobile source air toxics (MSATs). The primary purpose of this section is to discuss the fuel program being promulgated today. We discuss the form of the rule, major areas of comment including our response and final decisions on those aspects, and the details of the fuels program. We also discuss why we are not at this time considering other fuel controls as a means of reducing MSATs. The details of our technical analyses of these fuel issues can be found in Chapter 7 of the Technical Support Document (TSD). The Response to Comments Document contains our responses to all of the relevant comments on the fuels aspects of this rulemaking. A. Form of the Rule 1. What Is the Form of the Rule EPA Is Promulgating Today? We are finalizing new toxics emissions performance requirements (TPR) for gasoline. This anti-backsliding program will require, beginning with calendar year 2002, that a refinery's or importer's annual average total toxics emissions performance, as predicted by the Complex Model, for its baseline production volume of reformulated gasoline (RFG) not exceed its 1998-2000 baseline RFG total toxics emissions performance. Likewise for conventional gasoline (CG), this rule will require that the exhaust toxics emissions performance of a refinery's or importer's baseline production volume of CG not exceed its 1998-2000 baseline exhaust toxics emissions performance for CG. The 1998-2000 baseline RFG or CG toxics emissions performance value is the average performance of the gasoline produced at the refinery (or imported) over the three year period 1998 through 2000. Emission values are determined using the Complex Model, 19 and compliance with the program is determined separately for RFG and CG. We have included in our program a number of compliance flexibilities, such as a deficit and credit carryforward, and a compliance margin, to offset unexpected or unusual variances in the gasoline quality of a refinery (or importer). We believe that these provisions will help to ensure that this program does not require new capital investments or changes in refinery operations, and thus will not pose an additional burden on refiners. Were this program to require new investments in the refining sector, we would be concerned that it would impose an economic burden on refiners that would be inconsistent with our finding that an anti-backsliding program at negligible cost is the most stringent program that we can justify in the near term. 19 The Complex Model is a regulatory tool for estimating emissions for the reformulated gasoline and anti-dumping programs. The Complex Model inputs are eight specified fuel parameters: benzene, oxygen content (by oxygenate type), sulfur, Reid Vapor Pressure, aromatics, olefins and the percents evaporated at 200°F and 300°F (E200 and E300). Complex Model outputs are the estimated emissions (VOC, toxics, NO X ) resulting from the fuel parameters specified. The Complex Model also calculates percent reductions of the input slate of fuel parameters and resulting emissions compared to a base set of fuel parameters and resulting base emissions. The current rule is designed to avoid increases in toxic emissions from gasoline while imposing the least cost on the refining industry. Some have claimed that a refinery-specific performance requirement is inherently unfair because those refineries that have overcomplied to the greatest extent will receive the most stringent new baseline requirement. We recognize generally that setting standards based on current production may appear to penalize those who have voluntarily overcomplied. In fact, there is at least one refinery that has sought and received Agency recognition for its efforts to voluntarily overcomply with existing requirements. The Agency recognizes as a general matter the importance of providing appropriate incentives for the regulated community to take actions consistent with improving the environment. However, in this case, we believe that setting refinery-specific standards is the most appropriate and equitable approach to ensuring that emissions do not increase above current levels. As we explained in the NPRM, we believe that these refineries that have overcomplied have done so primarily because it was economically advantageous. In most cases, the financial incentive to overcomply is due to proximity to a market for chemical benzene. If the Agency were to establish a single, nationwide standard, commenters could legitimately characterize such an action as penalizing those refineries that are not located near petrochemical markets. Since each refinery is unique in terms of construction and location, any single standard will create varying degrees of challenges. Faced with a situation where a significant number of refineries have overcomplied with existing standards, the Agency has sought to craft a rule that represents the greatest degree of emission reductions achievable considering costs. The regulation that we finalize today achieves these goals. 2. Why Did EPA Change From the Proposed Benzene Fuel Content Form of the Rule to the TPR? In the Notice of Proposed Rulemaking, we proposed a benzene content requirement in order to capture the significant amount of overcompliance above and beyond the requirements of the federal reformulated gasoline and anti-dumping programs. Average benzene levels in 1998 and 1999 were 0.66 volume percent for RFG and 1.11 volume percent for conventional gasoline. These national average benzene levels are significantly below current requirement of 0.95 volume percent for RFG and average conventional gasoline baselines of 1.3 volume. Benzene emissions account for roughly 70% of motor vehicle air toxics (i.e., benzene, formaldehyde, acetaldehyde, 1,3-butadiene and POM). The Agency asked for comment on two other forms of the rule: benzene emissions performance and toxics emissions performance. The Agency did not propose a toxics performance form because of concerns that capping the total mass of toxics would allow benzene emissions to potentially increase if other air toxics declined. However, subsequent refinery modeling showed that benzene emissions would be unlikely to increase in the future following implementation of RFG Phase II and Tier 2 low sulfur gasoline standards, and the proposed low sulfur diesel standards. We viewed a benzene emissions requirement as tantamount to a benzene content requirement, but more difficult to quantify and enforce because there is not currently such a rule in effect. We received a significant number of comments on this proposal during the public hearing and in written comments submitted to the Agency. In general, commenters from the petroleum industry stated that there are significant costs associated with the benzene content form of the rule. These same commenters pointed out that there was little environmental benefit to the proposed requirements to justify their costs. Others commented that the Agency's concern about benzene emissions would be better served by a performance requirement since there is expected to be upward pressure on aromatics due to future environmental regulations and capping benzene fuel content will not prevent increases in fuel aromatics. Several commenters found that the rule did not go far enough to protect public health and welfare from the potential risk from mobile source air toxics. In response to these comments, and based on refinery modeling performed for this rulemaking, the Agency will finalize a toxics performance requirement instead of a benzene content requirement. The Agency's general rationale is twofold: a toxics performance requirement captures a larger amount of the overcompliance with the existing standards while imposing less costs on the refining industry than the proposed benzene content requirement. This action is consistent with comments received from the regulated industry and the Agency's updated refinery modeling. Evaluation of a Benzene Content Standard The Agency evaluated the benzene content standard in terms of its expected environmental performance and its potential cost to industry. Section 112(k) of the Clean Air Act identifies five toxic air pollutants related to gasoline—benzene, 1,3-butadiene, acetaldehyde, formaldehyde and POM. Benzene emissions are about 70 percent of the total mass of these toxics, but all of these toxics are known or probable human carcinogens and pose a risk to public health and welfare. Benzene emissions are a function of benzene fuel content, but other components in the fuel also influence benzene emissions, such as total aromatics, sulfur, and Reid Vapor Pressure. Controlling the benzene content of RFG and CG would in effect control only a portion of the benzene emissions, which in turn are only a portion of total toxic emissions. The Agency is concerned ultimately with reducing ambient concentrations and exposure to air toxics. The costs related to a benzene content standard were calculated using a refinery model. The Agency found that a benzene content standard would impose aggregate annual costs (including amortized capital and all the operating costs) of $74 million for refineries in PADDs I, II, and III. On a per gallon basis, the annual cost of the proposed benzene content standard was predicted to be 0.0702 c/gal. Since gasoline production in PADDs I, II, and III represents about 91% of the national gasoline supply without California refiners, if we extrapolate this cost to the rest of the U.S., the aggregate cost would be approximately $81 million for the nation. California gasoline production is not included in this cost analysis because this regulation does not apply to California gasoline. It is important to note that there are some advantages related to fuel content standards. Compliance and enforcement are aided by the ability to test the fuel rather than relying on estimates derived from a model. A fuel content standard does not rely on an emissions model that may not fully estimate emissions from the vehicle fleet on the road today or in the future. Thus the decision to shift from a fuel content to an emissions based requirement in this rule should not be viewed by the reader as suggesting that the Agency in a general sense is no longer interested in controls on specific fuel components. It is simply in this particular case that we found an emissions performance requirement to be superior under a combined consideration of broader environmental benefits and lower costs. Evaluation of a Toxics Performance Requirement There are several advantages for adopting a toxics performance requirement. It allows for a more comprehensive approach to capping air toxics emissions at current levels. By focusing on the five toxic compounds modeled by the Complex Model instead of only benzene, the mass emissions of air toxics placed under anti-backsliding constraints is substantially increased. Also, by focusing on emissions instead of fuel content, the new rule will establish an appropriate performance requirement while simultaneously providing some additional flexibility to regulated entities. Finally, it offers broader protection to public health because all five toxics included in the toxics performance requirement are known or probable human carcinogens. Section 202(l)(2) of the Clean Air Act instructs the Agency to promulgate regulations that, at a minimum, apply to emissions of benzene and formaldehyde. The shift to a toxics emissions performance requirement will limit emissions of these two pollutants along with emissions of 1,3-butadiene, POM and acetaldehyde. Thus, while refiners will have the ability to adjust fuel parameters in ways that will increase the emissions of one or more of these pollutants, any such increase must be offset by reductions in the emissions of the other pollutants. All of the pollutants covered by the toxics performance control are carcinogens. The nationwide inventories and ambient concentrations of all of these five pollutants are heavily influenced by motor vehicle emissions. Without today's anti-backsliding program, the current standards would leave room for toxics emissions from gasoline-fueled motor vehicles to increase by 70,000 tons per year (based on 1996 inventory levels) as described in the Technical Support Document. This would amount to a 14% increase, on average, in RFG areas, and a 18% increase, on average, in CG areas. Capping the overall toxics emissions performance of gasoline to reflect current overcompliance is an appropriate means of addressing the potential adverse public health impacts that could occur if this backsliding from current levels were to occur. While we are not able to quantify the risk to public health that would result if backsliding were to occur, we believe a precautionary approach is appropriate. By adopting anti-backsliding controls, this precautionary approach will protect public health by reducing the potential risks to public health from backsliding. The Act also instructs the Agency to take costs into consideration. As stated previously, numerous petroleum refineries provided written testimony that a benzene content requirement would impose significant costs on the industry. The Agency conducted refinery modeling for this rule which accounted for the impact on refinery operations and fuel properties of Tier 2 low sulfur gasoline and low sulfur diesel fuel. This modeling analysis, discussed in more detail in the TSD, found that the costs associated with the benzene content requirement were significantly higher than the costs that a toxics performance requirement would impose on the industry. 3. What Are the Benefits of the TPR? The purpose of today's action is to prevent future increases above the current level of air toxic emissions derived from existing fuel properties. This anti-backsliding measure will ensure that mass emission rates (in milligrams per mile, mg/mi) of air toxics from motor vehicles do not increase while the Agency gathers additional information for a forthcoming rulemaking in 2003-2004. The Clean Air Act identified five air toxics in the federal reformulated gasoline program: benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and POM. The RFG program established a toxics emissions performance standard for RFG, and an anti-backsliding toxics standard for conventional gasoline based on 1990 baseline toxics levels for each refinery. On average, refineries have overcomplied with the toxics emissions performance standards for both RFG and CG. Table V-1 compares the percent reductions required for RFG Phase I and the national average CG mass toxics emissions with actual national average performance in 1998, which was the most recent year for which complete and accurate data was available. On a national average, greater overcompliance was experienced for RFG than for CG. Table V-1.—Overcompliance With Toxics Performance Standards for RFG and CG Phase I Standards 1998 Average Percent difference in emissions (Percent) RFG, Percent Reduction from statutory baseline, Total Toxics Performance (equivalent mg/mi) 16.5% reduction (45.3 mg/mi) 28.1% reduction (38.4 mg/mi) 15% CG, Mass Emissions, 47.3 mg/mi a 44.7 mg/mi 6% Exhaust Toxics Performance a Volume-weighted average of refinery-specific standards. The 1998 average values were based on volume-weighted toxics performance values for batch reports for all refineries in the U.S. which produced gasoline in 1998. The data available to us at this time does not allow us to account for the impact of imports on these nationwide average values. The values in Table V-1 differ slightly from those in the NPRM because we excluded noncomplying refineries from the analysis and volume-weighted only actual emissions in units of mg/mi instead of percent change values for each refinery. Overcompliance with RFG standards resulted in substantial toxics reductions beyond what was required by law. We have estimated reductions in the total toxics inventories due to overcompliance of 70 thousand tons in 1996 and 40 thousand tons in 2007, using the inventories from the 1999 EPA Motor Vehicle Air Toxics Study (see TSD). While we do not believe that refiners are likely to increase their toxics content in the absence of this regulation, it is nonetheless important to ensure that these benefits are maintained in the event of unforeseen circumstances that may otherwise result in backsliding on toxics standards up to existing legal limits. Without this regulation, such backsliding could occur if refineries increase benzene or aromatics to increase octane levels, or if they change their refinery operations in reaction to unforeseen future circumstances. 4. What Are the Costs of the TPR? In conjunction with this rulemaking, we analyzed refinery modeling results for gasoline production regions in the Atlantic and Gulf Coasts, specifically PADDs 20 I and III. This modeling analysis used the average regional gasoline fuel properties produced in 1999 to quantify the emissions performance of gasoline in these regions in 1999. The refinery modeling also predicted the likely regional fuel properties after refineries modified their operations to comply with the future requirements for Phase II RFG, Tier 2 low sulfur gasoline, and proposed low sulfur diesel fuel (hereafter future fuel regulations). The Agency applied the Complex Model to evaluate the projected emissions performance of the predicted gasoline properties in these regions. The reader should refer to the TSD which accompanies this rule for more detailed discussion of the refinery modeling. 20 Petroleum Administration for Defense Districts. The Agency is currently pursuing a separate rulemaking under the Toxic Substances Control Act (TSCA) to address the use of MTBE, and thus we have deferred consideration of MTBE controls to that rulemaking. Note that the EPA and the United States Department of Agriculture jointly announced, on March, 2000, the Administration's legislative principles for protecting drinking water supplies, preserving clean air benefit and promoting renewable fuels and urged Congress to take action consistent with these principles. These actions were based initially on recommendations of EPA's Blue Ribbon Panel on Oxygenates in Gasoline. The Agency recognizes that the use of MTBE does have an impact on emissions of toxic air pollutants from motor vehicles. The Blue Ribbon Panel found that present toxic emission performance of RFG can be attributed, to some degree, to the use of oxygenates. Further, the Panel recommended that any future change in the use of MTBE in gasoline should “ensure that there is no loss of current air quality benefits.” 21 The anti-backsliding nature of this rulemaking is consistent with the Panel's recommendations. Should the Agency take action in the future to limit the amount of MTBE in fuel, its impact on emissions of air toxics—and the potential for additional costs due to today's action—would be carefully considered. As EPA develops any regulatory actions to address MTBE and water resource issues, the Agency will consider the overall impact on the refining industry of any such action and, along with today's rule, and other relevant factors. 21 Achieving Clean Air and Clean Water: The Report of the Blue Ribbon Panel on Oxygenates in Gasoline, EPA420-R-99-21, September, 1999, at 6-7. Because the new baseline requirements do not require refiners to install new equipment or use new technologies beyond what they were using in the baseline period (1998-2000), this program imposes only negligible costs. This conclusion is based on our analyses of likely refiner behavior based on the expected requirements in the time frame applicable for this rulemaking. Unforeseen circumstances could change a refiner's actions needed to comply with this rule, which in turn could lead to additional costs depending on their chosen course of action. In contrast, the proposed benzene content standard was predicted to impose higher costs while capturing a smaller amount of the existing overcompliance with toxic standards. As stated previously, the Agency found that a benzene content standard would impose aggregate annual costs (including amortized capital and all the operating costs) of $74 million for refineries in PADDs I, II, and III. On a per gallon basis, the annual cost of the proposed benzene content standard was predicted to be 0.0702 c/gal. Since gasoline production in PADDs I, II, and III represents about 91% of the national gasoline supply without California refiners, if we extrapolate this cost to the rest of the U.S., the aggregate cost would be approximately $81 million for the nation. California gasoline production is not included in this cost analysis because this regulation does not apply to California gasoline. There are limitations to the ability of a refinery model to predict the costs associated with each refinery. This inherent limitation of refinery modeling is of particular concern with the refinery-specific requirement that is adopted today. To help ensure that each refinery affected by this rule is faced with the type of costs estimated by the Agency's refinery modeling, we incorporated several flexibilities into the final rule. We have expanded the baseline period from two to three years, provided a one-year carryforward for credits and deficits, and adopted compliance margins for RFG and CG. B. Issues and Areas of Comment on Non-implementation Related Aspects of the Program 1. What Is the Relationship Between the RFG and Anti-dumping Requirements and the Toxics Anti-backsliding Requirements? The reformulated gasoline program established a toxics performance standard for gasoline used in those metropolitan areas with the worst ozone levels. An anti-dumping toxics standard was established for gasoline used in those areas not required to have RFG and which did not opt to use RFG. The anti-dumping toxics standard was intended to prevent refineries from shifting certain less desirable fuel components into the conventional gasoline pool as a result of RFG production. The anti-dumping program was an anti-backsliding program for exhaust toxics and NO X relative to the baseline year of that program, 1990. Today's anti-backsliding requirements are in addition to the applicable RFG or anti-dumping requirements for gasoline. Today we are establishing refinery-specific toxics performance requirements (TPR) for reformulated and conventional gasoline. A refiner will now have to meet both today's toxics requirements and the applicable toxics performance for RFG or anti-dumping. In the NPRM, we asked for comment on repealing the anti-dumping program. We received comments from many refiners in support of this recommendation from the National Petrochemical & Refiners Association (NPRA). However, we find that we cannot repeal the anti-dumping program. The anti-dumping program is required by the [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%3A01-37. Public record. Not legal advice.