[Federal Register Volume 78, Number 98 (Tuesday, May 21, 2013)]
[Proposed Rules]
[Pages 29815-30191]
[FR Doc No: 2013-08500]

Vol. 78

Tuesday,

No. 98

May 21, 2013

Part II

Environmental Protection Agency

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40 CFR Parts 79, 80, 85 et al.

 Control of Air Pollution From Motor Vehicles: Tier 3 Motor Vehicle
Emission and Fuel Standards; Proposed Rule

Federal Register / Vol. 78 , No. 98 / Tuesday, May 21, 2013 /
Proposed Rules

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 79, 80, 85, 86, 600, 1036, 1037, 1065, and 1066

[EPA-HQ-OAR-2011-0135; FRL-9785-8]
RIN 2060-AQ86

Control of Air Pollution From Motor Vehicles: Tier 3 Motor
Vehicle Emission and Fuel Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed Rule.

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SUMMARY: This action would establish more stringent vehicle emissions
standards and reduce the sulfur content of gasoline beginning in 2017,
as part of a systems approach to addressing the impacts of motor
vehicles and fuels on air quality and public health. The proposed
gasoline sulfur standard would make emission control systems more
effective for both existing and new vehicles, and would enable more
stringent vehicle emissions standards. The proposed vehicle standards
would reduce both tailpipe and evaporative emissions from passenger
cars, light-duty trucks, medium-duty passenger vehicles, and some
heavy-duty vehicles. This would result in significant reductions in
pollutants such as ozone, particulate matter, and air toxics across the
country and help state and local agencies in their efforts to attain
and maintain health-based National Ambient Air Quality Standards. Motor
vehicles are an important source of exposure to air pollution both
regionally and near roads. These proposed vehicle standards are
intended to harmonize with California's Low Emission Vehicle program,
thus creating a federal vehicle emissions program that would allow
automakers to sell the same vehicles in all 50 states. The proposed
vehicle standards would be implemented over the same timeframe as the
greenhouse gas/fuel efficiency standards for light-duty vehicles, as
part of a comprehensive approach toward regulating emissions from motor
vehicles.

DATES: Comments. Comments must be received on or before June 13, 2013.
    Public Hearing: The public hearings were held on April 24, 2013 in
Philadelphia, PA and April 29, 2013 in Chicago, IL.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2011-0135, by one of the following methods:
     www.regulations.gov: Follow the on-line instructions for
submitting comments.
     Email<EMAIL_ADDRESS>     Mail: Air and Radiation Docket and Information Center,
Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania
Ave. NW., Washington, DC 20460. In addition, please mail a copy of your
comments on the information collection provisions to the Office of
Information and Regulatory Affairs, Office of Management and Budget
(OMB), Attn: Desk Officer for EPA, 725 17th St. NW., Washington, DC
20503.
     Hand Delivery: EPA Docket Center, EPA West Building, Room
3334, 1301 Constitution Ave. NW., Washington, DC 20460. Such deliveries
are only accepted during the Docket's normal hours of operation, and
special arrangements should be made for deliveries of boxed
information.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-
2011-0135. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
www.regulations.gov, including any personal information provided,
unless the comment includes information claimed to be Confidential
Business Information (CBI) or other information whose disclosure is
restricted by statute. Do not submit information that you consider to
be CBI or otherwise protected through www.regulations.gov or email. The
www.regulations.gov Web site is an ``anonymous access'' system, which
means EPA will not know your identity or contact information unless you
provide it in the body of your comment. If you send an email comment
directly to EPA without going through www.regulations.gov your email
address will be automatically captured and included as part of the
comment that is placed in the public docket and made available on the
Internet. If you submit an electronic comment, EPA recommends that you
include your name and other contact information in the body of your
comment and with any disk or CD-ROM you submit. If EPA cannot read your
comment due to technical difficulties and cannot contact you for
clarification, EPA may not be able to consider your comment. Electronic
files should avoid the use of special characters, any form of
encryption, and be free of any defects or viruses. For additional
information about EPA's public docket visit the EPA Docket Center
homepage at http://www.epa.gov/epahome/dockets.htm. For additional
instructions on submitting comments, go to Section I.B of the
SUPPLEMENTARY INFORMATION section of this document.
    Docket: All documents in the docket are listed in the
www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in hard copy.
Publicly available docket materials are available either electronically
in www.regulations.gov or in hard copy at the Air and Radiation Docket
and Information Center, EPA/DC, EPA West, Room 3334, 1301 Constitution
Ave. NW., Washington, DC. The Public Reading Room is open from 8:30
a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The
telephone number for the Public Reading Room is<PHONE_NUMBER>, and the
telephone number for the Air Docket is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: JoNell Iffland, Office of
Transportation and Air Quality, Assessment and Standards Division
(ASD), Environmental Protection Agency, 2000 Traverwood Drive, Ann
Arbor, MI 48105; Telephone number:<PHONE_NUMBER>; Fax number: (734)
214-4816; Email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this action apply to me?

    Entities potentially affected by this proposed rule include
gasoline refiners and importers, ethanol producers, gasoline additive
manufacturers, transmix processors, terminals and fuel distributors,
light-duty vehicle manufacturers, independent commercial importers,
alternative fuel converters, and manufacturers and converters of
vehicles between 8,500 and 14,000 lbs gross vehicle weight rating
(GVWR).
    Potentially regulated categories include:

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                                                                                Examples of potentially affected
                 Category                   NAICS \a\ Code     SIC \b\ Code                 entities
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Industry.................................            324110              2911  Petroleum refineries (including
                                                                                importers).
Industry.................................            325110              2869  Butane manufacturers.

Industry.................................            325193              2869  Ethyl alcohol manufacturing.
Industry.................................            211112              1321  Natural gas liquids extraction
                                                                                and fractionation.
Industry.................................            325199              2869  Other basic organic chemical
                                                                                manufacturing.
Industry.................................            486910              4613  Natural gas liquids pipelines,
                                                                                refined petroleum products
                                                                                pipelines.
Industry.................................            424690              5169  Chemical and allied products
                                                                                merchant wholesalers.
Industry.................................            325199              2869  Manufacturers of gasoline
                                                                                additives.
Industry.................................            424710              5171  Petroleum bulk stations and
                                                                                terminals. E51-83 manufacturers.
Industry.................................            493190              4226  Other warehousing and storage-
                                                                                bulk petroleum storage.
Industry.................................           336111,              3711  Light-duty vehicle and light-duty
                                                     336112                     truck manufacturers.
Industry.................................           811111,             7538,  Independent commercial importers.
                                                    811112,             7533,
                                                     811198              7534
Industry.................................           335312,             3621,  Alternative fuel converters.
                                                    336312,             3714,
                                                    336322,             3519,
                                                    336399,             3599,
                                                     811198              7534
Industry.................................           333618,             3699,  On-highway heavy-duty engine &
                                                    336120,             3711,   vehicle (>8,500 lbs GVWR)
                                                    336211,             3713,   manufacturers.
                                                     336312              3714
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\a\ North American Industry Classification System (NAICS).
\b\ Standard Industrial Classification (SIC).

    This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
proposed action. This table lists the types of entities that EPA is now
aware could potentially be regulated by this proposed action. Other
types of entities not listed in the table could also be regulated. To
determine whether your activities would be regulated by this proposed
action, you should carefully examine the applicability criteria in 40
CFR parts 79, 80, 85, 86, 1065, and 1066 and the referenced
regulations. If you have any questions regarding the applicability of
this proposed action to a particular entity, consult the person listed
in the preceding FOR FURTHER INFORMATION CONTACT section.

B. What should I consider as I prepare my comments for EPA?

1. Submitting CBI
    Do not submit this information to EPA through www.regulations.gov
or email. Clearly mark the part or all of the information that you
claim to be CBI. For CBI information in a disk or CD ROM that you mail
to EPA, mark the outside of the disk or CD ROM as CBI and then identify
electronically within the disk or CD ROM the specific information that
is claimed as CBI. In addition to one complete version of the comment
that includes information claimed as CBI, a copy of the comment that
does not contain the information claimed as CBI must be submitted for
inclusion in the public docket. Information so marked will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2.
2. Tips for Preparing Your Comments
    When submitting comments, remember to:
     Identify the rulemaking by docket number and other
identifying information (subject heading, Federal Register date and
page number).
     Follow directions--The agency may ask you to respond to
specific questions or organize comments by referencing a Code of
Federal Regulations (CFR) part or section number.
     Explain why you agree or disagree, suggest alternatives,
and substitute language for your requested changes.
     Describe any assumptions and provide any technical
information and/or data that you used.
     If you estimate potential costs or burdens, explain how
you arrived at your estimate in sufficient detail to allow for it to be
reproduced.
     Provide specific examples to illustrate your concerns, and
suggest alternatives.
     Explain your views as clearly as possible, avoiding the
use of profanity or personal threats.
     Make sure to submit your comments by the comment period
deadline identified.

C. Did EPA conduct a peer review before issuing this notice?

    This regulatory action was supported by influential scientific
information. Therefore, EPA conducted peer reviews in accordance with
OMB's Final Information Quality Bulletin for Peer Review. Specifically,
EPA conducted six peer reviews in connection with data supporting the
proposed Tier 3 program, including new research on the effects of fuel
properties changes (including sulfur effects) on exhaust and
evaporative emissions of Tier 2 vehicles. The refinery-by-refinery cost
model was also peer reviewed. The peer review reports are located in
the docket for today's action, as well as the agency's response to the
peer review comments.

Table of Contents

I. Executive Summary and Overview of Proposed Program
    A. Introduction
    B. What are the basic components of the proposed program?
    1. Proposed Standards for Light-Duty Vehicle, Light-Duty Truck,
and Medium-Duty Passenger Vehicle Tailpipe Emissions
    2. Proposed Heavy-Duty Vehicle Tailpipe Emissions Standards
    3. Proposed Evaporative Emission Standards
    4. Onboard Diagnostic Systems (OBD)
    5. Emissions Test Fuel
    6. Fuel Standards
    7. Regulatory Streamlining and Technical Amendments
    C. What would the impacts of the proposed standards be?
II. Why is EPA making this proposal?
    A. Basis for Action Under the Clean Air Act
    1. Clean Air Act Section 202
    2. Clean Air Act Section 211
    B. Overview of Public Health Impacts of Motor Vehicles and Fuels
    1. Ozone
    2. Particulate Matter
    3. Nitrogen Oxides and Sulfur Oxides
    4. Carbon Monoxide

    5. Mobile Source Air Toxics
    6. Near-Roadway Pollution
    7. Environmental Impacts of Motor Vehicles and Fuels
III. How would this proposal reduce emissions and air pollution?
    A. Effects of the Proposed Vehicle and Fuel Changes on Mobile
Source Emissions
    1. How do vehicles produce the emissions addressed in this
proposal?
    2. How would the proposed changes to gasoline sulfur content
affect vehicle emissions?
    B. How would emissions be reduced?
    1. NOX
    2. VOC
    3. CO
    4. Direct PM2.5
    5. Air Toxics
    6. SO2
    7. Greenhouse Gases
    C. How would air pollution be reduced?
    1. Ozone
    2. Particulate Matter
    3. Nitrogen Dioxide
    4. Air Toxics
    5. Visibility
    6. Nitrogen and Sulfur Deposition
    7. Environmental Justice
IV. Proposed Vehicle Emissions Program
    A. Tailpipe Emission Standards for Light-Duty Vehicles, Light-
Duty Trucks, and Medium-Duty Passenger Vehicles
    1. Overview
    2. Summary of Proposed FTP and SFTP Tailpipe Standards
    3. Proposed FTP Standards
    4. Proposed SFTP Standards
    5. Feasibility of the Proposed NMOG+NOX and PM
Standards
    6. Impact of Gasoline Sulfur Control on the Feasibility of the
Proposed Vehicle Emission Standards
    7. Other Provisions
    B. Tailpipe Emissions Standards for Heavy-Duty Vehicles
    1. Overview
    2. HDV Exhaust Emissions Standards
    3. Supplemental FTP Standards for HDVs
    4. HDV Emissions Averaging, Banking, and Trading
    5. Feasibility of HDV Standards
    6. Other HDV Provisions
    C. Evaporative Emissions Standards and Onboard Diagnostic System
Requirements
    1. Tier 3 Evaporative Emission Standards
    2. Evaporative Emissions Program Structure and Implementation
Flexibilities
    3. Heavy-Duty Gasoline Vehicle (HDGV) Requirements
    4. Test Procedures and Certification Test Fuel
    5. Improvements to In-Use Performance of Fuel Vapor Control
Systems
    6. Other Initiatives
    D. Emissions Test Fuel
    1. Proposed Changes to Gasoline Emissions Test Fuel
    2. Proposed Flexible Fuel Vehicle Test Fuel
    3. Proposed Implementation Schedule
    4. Potential Implications on CAFE Standards, GHG Standards, and
Fuel Economy Labels
    5. Consideration of Nonroad, Motorcycle, and Heavy-Duty Engine
Emissions Test Fuel
    6. Consideration of CNG and LPG Emissions Test Fuel
    E. Small-Business Provisions
    1. Lead Time for Exhaust and Evaporative Emission Standards
    2. Assigned Deterioration Factors
    3. Reduced Testing Burden
    4. Hardship
    5. Applicability of Flexibilities
    F. Compliance Provisions
    1. Exhaust Emission Test Procedures
    2. Reduced Test Burden
    3. Miscellaneous Provisions
    4. Manufacturer In-Use Verification Testing (IUVP) Requirements
V. Proposed Fuel Program
    A. Proposed Tier 3 Gasoline Sulfur Standards
    1. Overview
    2. Proposed Annual Average Sulfur Standard
    3. Per-Gallon Sulfur Caps
    B. Refinery Air Permitting Interactions
    1. Background on New Source Review Programs
    2. Background on NSR Experience Under the Tier 2 Fuel Program
    3. Changes in the NSR Permitting Program since Tier 2 Final Rule
    4. Assessment of Tier 3 Refinery Changes and Permitting
Implications
    5. New Source Performance Standards and National Emission
Standards for Hazardous Air Pollutants for Refineries
    6. Steps for Streamlining the Permitting Process
    C. Standards for Denatured Fuel Ethanol and Other Oxygenates
    D. Standards for Fuel Used in Flexible Fueled Vehicles
    1. Standards for E51-83
    2. Standards for Mid-Level Ethanol Blends (E16-50)
    E. Proposed Program Flexibilities
    1. Averaging, Banking, and Trading Program
    2. Regulatory Flexibility Provisions
    3. Provisions for Refiners Facing Hardship Situations
    F. Compliance Provisions
    1. Registration, Reporting, and Recordkeeping Requirements
    2. Sampling and Testing Requirements
    3. Small Refiner Compliance
    4. Small Volume Refinery Compliance
    5. Attest Engagements, Violations, and Penalties
    6. Special Fuel Provisions and Exemptions
    G. Statutory Authority for Proposed Tier 3 Fuel Controls
    1. Section 211(c)(1)(A)
    2. Section 211(c)(1)(B)
VI. Technical Amendments and Regulatory Streamlining
    A. Amendments to 40 CFR Parts 79 and 80
    1. Regulatory Streamlining
    2. Subpart I Technical Amendments
    3. Performance-Based Measurement Systems (PBMS)
    4. Downstream Pentane Blending
    B. Engine, Vehicle and Equipment Programs
    1. Fuel Economy Labeling
    2. Removing Obsolete Regulatory Text
    3. Motorcycle Driving Schedules
    4. Updating Reference Procedures
VII. What are the cost impacts of the proposed rule?
    A. Estimated Costs of the Vehicle Standards
    B. Estimated Costs of the Fuel Program
    1. Overview
    2. Methodology
    3. Summary of Costs Without ABT Program
    4. Summary of Costs With ABT Program
    5. Other Cost Estimates
    C. Summary of Proposed Program Costs
    D. Cost per Ton of Emissions Reduced
VIII. What are the estimated benefits of the proposed rule?
    A. Overview
    B. Quantified Human Health Impacts
    C. Monetized Benefits
    D. What are the limitations of the benefits analysis?
    E. Illustrative Analysis of Monetized Impacts Associated With
the Proposal in 2017
IX. Alternatives Analysis
    A. Vehicle Emission Standards
    1. Shorter NMOG+NOX Standard Phase-in
    2. Longer NMOG+NOX Standards Phase-in Due to Early
Credits
    3. Shorter PM Standards Phase-in
    4. NMOG+NOX Standards
    5. PM Standards
    B. Fuel Sulfur Standards
X. Economic Impact Analysis
    A. Introduction
    B. Vehicle Sales Impacts
    C. Impacts on Petroleum Refinery Sector Production
    D. Employment Impacts
    1. Employment Impacts in the Auto Sector
    2. Refinery Employment Impacts
XI. Public Participation
    A. How do I submit comments?
    B. How should I submit CBI to the Agency?
    C. What should I consider as I prepare my comments for EPA?
    D. Will there be a public hearing?
XII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    1. Overview
    2. Background
    3. Reason for Today's Proposed Rule
    4. Legal Basis for Agency Action
    5. Summary of Potentially Affected Small Entities
    6. Potential Reporting, Recordkeeping, and Compliance
    7. Related Federal Rules
    8. Summary of SBREFA Panel Process and Panel Outreach
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That

Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
XIII. Statutory Provisions And Legal Authority

I. Executive Summary and Overview of Proposed Program

A. Introduction

    In this action, EPA is proposing a major program designed to reduce
air pollution from passenger cars and trucks. This program includes new
standards for both vehicle emissions and the sulfur content of
gasoline, considering the vehicle and its fuel as an integrated system.
We refer to this proposed program as the ``Tier 3'' vehicle and fuel
standards.
    This proposed rule is part of a comprehensive approach to address
the impacts of motor vehicles on air quality and public health. Over
158 million Americans are currently experiencing unhealthy levels of
air pollution, which are linked with respiratory and cardiovascular
problems and other adverse health impacts that lead to increased
medication use, hospital admissions, emergency department visits, and
premature mortality.\1\ Motor vehicles are a particularly important
source of exposure to air pollution, especially in urban areas. By 2014
we project that in many nonattainment areas, cars and light trucks will
contribute 30-45 percent of total nitrogen oxides (NOX)
emissions, 20-25 percent of total volatile organic compound (VOC)
emissions, and 5-10 percent of total direct particulate matter
(PM2.5) emissions.\2\ These compounds form ozone, PM, and
other air pollutants, whose health and environmental effects are
described in more detail in Section II. Cars and light trucks also
continue to be a significant contributor to air pollution directly near
roads, with gasoline vehicles accounting for more than 50 percent of
near-road concentrations of some criteria and toxic pollutants.\3\ More
than 50 million people live, work, or go to school in close proximity
to high-traffic roadways, and the average American spends more than one
hour traveling along roads each day.4 5 Almost 90 percent of
daily trips use personal vehicles.\6\
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    \1\ Data come from Summary Nonattainment Area Population
Exposure Report, current as of December 14, 2012 at: http://www.epa.gov/oar/oaqps/greenbk/popexp.html and contained in Docket
EPA-HQ-OAR-2011-0135.
    \2\ Mobile source contributions derived from inventories
developed for the Final Cross-State Air Pollution Rule (76 FR 48208,
August 8, 2011). For more information on these inventories see the
``Technical Support Document (TSD) for the final Transport Rule,
Docket ID No. EPA-HQ-OAR-2009-0491, Emissions Inventory Final Rule
TSD,'' available on the web at ftp://ftp.epa.gov/EmisInventory/2005v4_2/transportrulefinal_eitsd_28jun2011.pdf.
    \3\ For example, see Fujita, E.M; Campbell, D.E.; Zielinska, B.;
Arnott, W.P.; Chow, J.C. (2011) Concentrations of Air Toxics in
Motor Vehicle-Dominated Environments. Health Effects Institute
Research Report 156. Available at http://www.healtheffects.org
    \4\ U.S. Census Bureau (2011). Current Housing Reports, Series
H150/09, American Housing Survey for the United States: 2009. U.S.
Government Printing Office, Washington, DC. Available at http://www.census.gov/hhes/www/housing/ahs/ahs09/ahs09.html. (Note that
this survey includes estimates of homes within 300 feet of highways
with four or more lanes, railroads, and airports.)
    \5\ Drago, R. (2011). Secondary activities in the 2006 American
Time Use Survey. U.S. Bureau of Labor Statistics Working Paper 446.
Available at http://www.bls.gov.
    \6\ U.S. Department of Transportation, Bureau of Transportation
Statistics (2003). National Household Travel Survey 2001 Highlights
Report. Government Printing Office, Washington, DC. Available at
http://www.bts.gov/publications/highlights_of_the_2001_national_household_travel_survey/.
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    The standards set forth in this proposed rule would significantly
reduce levels of multiple air pollutants (such as ambient levels of
ozone, PM, nitrogen dioxide (NO2), and mobile source air
toxics (MSATs)) across the country, with immediate impacts expected due
to the proposed sulfur control standards starting in 2017. These
reductions would help state and local agencies in their effort to
attain and maintain health-based National Ambient Air Quality Standards
(NAAQS). Few other national strategies exist that would deliver the
same magnitude of multi-pollutant reductions projected to result from
the proposed Tier 3 standards. In the absence of additional controls,
many areas will continue to have ambient ozone concentrations exceeding
the NAAQS in the future. See Section III.C for more details.
    The Clean Air Act authorizes EPA to establish emissions standards
for motor vehicles to address air pollution that may reasonably be
anticipated to endanger public health or welfare (section 202). EPA
also has authority to establish fuel controls to address such air
pollution (section 211). These statutory authorities are described in
Section II.A.
    The vehicle and gasoline sulfur standards we are proposing
represent a ``systems approach'' to reducing vehicle-related exhaust
and evaporative emissions by addressing the vehicle and fuel as a
system. The systems approach enables emission reductions that are both
technologically feasible and cost-effective beyond what would be
possible looking at vehicle and fuel standards in isolation. We first
applied such an approach with our Tier 2 vehicle/gasoline sulfur
standards (finalized in 2000).\7\ We believe that a similar approach
for the proposed Tier 3 standards would be a cost-effective way to
achieve substantial additional emissions reductions.
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    \7\ 65 FR 6698 (February 10, 2000).
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    The proposed Tier 3 standards include new light- and heavy-duty
vehicle emission standards for exhaust emissions of VOC (specifically,
non-methane organic gases, or NMOG), NOX, and PM, as well as
evaporative emissions standards. The proposed standards for light-duty
vehicle, light-duty truck, and medium-duty passenger vehicle tailpipe
emissions are an 80 percent reduction in fleet average
NMOG+NOX compared to current standards, and a 70 percent
reduction in per-vehicle PM standards. The proposed Tier 3 heavy-duty
vehicle tailpipe emissions standards provide reductions in both
NMOG+NOX and PM that are on the order of 60 percent,
compared to current standards. The proposed evaporative emissions
standards represent a 50 percent reduction from current standards.
    The vehicle emission standards, combined with the proposed
reduction of gasoline sulfur content from the current 30 parts per
million (ppm) average down to a 10-ppm average, would result in
dramatic emissions reductions for NOX, VOC, direct
PM2.5, carbon monoxide (CO) and air toxics. For example, in
2030, when Tier 3 vehicles would make up the majority of the fleet as
well as vehicle miles travelled, NOX and VOC emissions from
on-highway vehicles would be reduced by about one quarter, and CO
emissions would be reduced by about 30 percent. Emissions of many air
toxics would also be reduced by 10 to nearly 40 percent of national
emissions from on-highway vehicles. Reductions would continue beyond
2030 as more of the fleet is composed of Tier 3 vehicles. For example,
the Tier 3 program would reduce on-highway emissions of NOX
and VOC nearly 40 percent by 2050, when Tier 3 vehicles would comprise
almost the entire fleet.
    Gasoline vehicles depend to a great degree on catalytic converters
to reduce levels of pollutants in their exhaust, including NMOG and
NOX, as well as PM (specifically, the volatile hydrocarbon
fraction), CO, and most air toxics. The catalytic converters become
significantly less efficient when sulfur

from the gasoline is deposited (adsorbed) onto the precious metals that
catalyze the reactions to reduce the emissions. The Tier 2 rulemaking
required refiners to take steps to reduce sulfur levels in gasoline by
approximately 90 percent, to an average of 30 ppm. As discussed in
Section IV.A.6, subsequent research provides a compelling case that
even this level of sulfur not only degrades the emission performance of
vehicles on the road today, but also inhibits necessary further
reductions in vehicle emissions performance to reach the proposed Tier
3 standards. Thus, the proposed Tier 3 10-ppm average sulfur standard
is significant in two ways: it enables vehicles designed to the
proposed Tier 3 tailpipe exhaust standards to meet these standards in-
use for the duration of their useful life, and it facilitates immediate
emission reductions from all the vehicles on the road at the time the
sulfur controls are implemented. Lower sulfur gasoline also facilitates
the development of lower-cost technologies to improve fuel economy.
Sulfur in the fuel quickly causes the fuel economy benefits of lean-
burn technologies to disappear due to its effect on NOx adsorber
operation requiring more fuel to be burned. We are not the first
regulatory agency to recognize the need for lower-sulfur gasoline.
Agencies in Europe and Japan have already imposed gasoline sulfur caps
of 10 ppm, and the State of California is already averaging 10 ppm
sulfur with a per gallon cap of 20 ppm. Other states are preempted by
the Clean Air Act from adopting new fuel programs to meet air quality
objectives. Consequently, they could not receive the air quality
benefits of lower sulfur gasoline without federal action.
    This proposal is one aspect of a comprehensive national program
regulating emissions from motor vehicles. EPA's recent final rule for
reducing greenhouse gas (GHG) emissions from light-duty (LD) vehicles
starting with model year (MY) 2017 (referred to here as the ``2017 LD
GHG'' standards) is another aspect of this comprehensive program.\8\
The Tier 3 proposal addresses interactions with the 2017 LD GHG rule in
a manner that aligns implementation of the two actions, to achieve
significant criteria pollutant and GHG emissions reductions while
providing regulatory certainty and compliance efficiency. As vehicle
manufacturers introduce new vehicle platforms for compliance with the
GHG standards, they will be able to design them for compliance with the
Tier 3 standards at the same time. The proposed Tier 3 standards are
also closely coordinated with California's Low Emission Vehicle (LEV
III) program to create a vehicle emissions program that would allow
automakers to sell the same vehicles in all 50 states. (In December
2012 EPA approved a waiver of Clean Air Act preemption for the
California Air Resources Board's (CARB's) LEV III program with
compliance beginning in 2015. Ten states have adopted the LEV III
program under Section 177 of the Clean Air Act.\9\) We have worked
closely with individual vehicle manufacturers and their trade
associations, who have emphasized the importance of a harmonized
national program. Together, the Tier 3, 2017 LD GHG, and LEV III
standards would maximize reductions in GHGs, criteria pollutants and
air toxics from motor vehicles while streamlining programs and enabling
manufacturers to design a single vehicle for nationwide sales, thus
reducing their costs of compliance. In this way, the Tier 3 proposal
responds to the May 21, 2010 Presidential Memorandum that requested
that EPA develop a comprehensive approach toward regulating motor
vehicles, including consideration of non-GHG emissions standards.\10\
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    \8\ 77 FR 62623 (October 15, 2012).
    \9\ These states include Connecticut, Maryland, Maine,
Massachusetts, New Jersey, New York, Pennsylvania, Rhode Island,
Washington, and Vermont.
    \10\ The Presidential Memorandum is found at: http://www.whitehouse.gov/the-press-office/presidential-memorandum-regarding-fuel-efficiency-standards.
---------------------------------------------------------------------------

    As part of the systems approach to this program, we are considering
the future fuels on which vehicles will be operating. In particular,
the renewable fuels mandate that was revised by the Energy Independence
and Security Act (EISA) and is being implemented through the Renewable
Fuel Standards program (RFS2)\11\ will result in significant amounts of
ethanol-blended gasoline in the implementation timeframe of the
proposed Tier 3 program. We are proposing to update the specifications
of the certification test fuel with which vehicles demonstrate
compliance with emissions standards, in order to better reflect the
ethanol content and other properties of gasoline that will be in use.
---------------------------------------------------------------------------

    \11\ 75 FR 14670 (March 26, 2010).
---------------------------------------------------------------------------

    This section provides an overview of the vehicle- and fuel-related
standards we are proposing as well as the impacts of the proposed
standards. The public health issues and statutory requirements that
have prompted this proposal are described in Section II, and our
discussion of how the proposal would reduce emissions and air pollution
is presented in Section III. Details of proposed standards and how they
would be implemented can be found in Sections IV through VI. Sections
VII through X contain our discussion of the proposed standards'
technological feasibility and cost, benefits, alternatives and economic
impacts.

B. What are the basic components of the proposed program?

    In the more than 10 years since EPA finalized the Tier 2 Vehicle
Program, manufacturers of light-duty vehicles have continued to develop
a wide range of improved technologies capable of reducing key exhaust
emissions, especially VOC, NOX, and PM. The California LEV
II program has been instrumental in the continuous technology
improvements by requiring year after year reductions in the fleet
average hydrocarbon levels, in addition to requiring the introduction
of advanced exhaust and evaporative emission controls in partial zero
emission vehicles (PZEVs). This progress in vehicle technology has made
it possible for manufacturers to achieve emission reductions well
beyond the requirements of the Tier 2 program if gasoline sulfur levels
are lowered further.
    As a result, we are proposing new standards for exhaust emissions
of NMOG, NOX, and PM, as well as evaporative emissions
standards. These standards would phase in beginning with MY 2017. The
proposed Tier 3 standards are very similar in structure to those in the
existing Tier 2 program. As with the Tier 2 program, the proposed
standards would apply to all light-duty vehicles (LDVs, or passenger
cars), light-duty trucks (LDT1s, LDT2s, LDT3s, and LDT4s) and Medium-
Duty Passenger Vehicles (or MDPVs). We are also proposing separate but
closely related standards for heavy-duty vehicles up to 14,000 lbs
Gross Vehicle Weight Rating (GVWR). These vehicles were not included in
Tier 2 but were made subject to new standards in a final rule that
covered the broad heavy-duty sector (66 FR 5002, January 18, 2001). We
have concluded that the proposed vehicle emissions standards, in
conjunction with the reductions in fuel sulfur also proposed in this
action, are feasible across the fleet in the proposed time frame.
    In the discussions of the various elements of our proposed program
for light- and heavy-duty vehicles throughout this preamble, we
describe how the provisions would be consistent with the California Air
Resources Board (CARB) LEV III program. Auto

manufacturers have stressed to us the importance of their being able to
design and produce a single fleet of vehicles in all 50 states that
would comply with requirements under the Tier 3 program and the LEV III
program, as well as greenhouse gas/Corporate Average Fuel Economy
(CAFE) requirements in the same timeframe. Consistency among the
federal and California programs means that special versions of vehicles
with different emission control hardware and calibrations would not be
necessary for different geographic areas. This would allow
manufacturers to avoid the additional costs of parallel design,
development, calibration, and manufacturing. Consistency among programs
would also eliminate the need to supply aftermarket parts for repair of
multiple versions of a vehicle. To that end, we worked closely with
CARB and with the vehicle manufacturers, both with individual companies
and with their trade associations, to align the two programs in most
respects.
    We have also designed the proposed Tier 3 program to be implemented
in the same timeframe as the federal and California GHG emissions and
fuel economy standards for model years 2017-2025. We expect that in
response to these programs, manufacturers will be developing entirely
new powertrains for most of their vehicles. Because the Tier 3
standards would phase in over the same timeframe, manufacturers would
be in a position to simultaneously respond to all of these
requirements.
1. Proposed Standards for Light-Duty Vehicle, Light-Duty Truck, and
Medium-Duty Passenger Vehicle Tailpipe Emissions
    We are proposing a comprehensive program that would include new
fleet-average standards for the sum of NMOG and NOX tailpipe
emissions (presented as NMOG+NOX) and for PM.\12\ These
proposed standards, when applied in conjunction with reduced gasoline
sulfur content, would result in very significant improvements in
vehicle emissions from the levels of the Tier 2 program. For these
pollutants, we are proposing standards as measured on test procedures
that represent a range of vehicle operation, including the Federal Test
Procedure (or FTP, simulating typical driving) and the Supplemental
Federal Test Procedure (or SFTP, a composite test simulating higher
temperatures, higher speeds, and quicker accelerations). In addition to
the standards, we are also proposing to extend the regulatory useful
life period during which the standards apply and to make test fuel more
representative of expected real-world fuel (see Section I.B.5 below).
---------------------------------------------------------------------------

    \12\ A discussion of the reasons for combining the two
pollutants for this purpose is in Section IV.A.3.a below.
---------------------------------------------------------------------------

    As discussed in Section IV.A.6., the impact of gasoline sulfur
poisoning on exhaust catalyst performance provides a compelling
argument, particularly for larger vehicles and trucks, that these
vehicle standards would be achievable only with a reduction of gasoline
sulfur content from the current 30-ppm average down to a 10-ppm
average. Sulfur is a well-known catalyst poison. The nature of sulfur's
interactions with active catalytic materials is complex and varies with
catalyst composition, exhaust gas composition and exhaust temperature.
Thus, even if a manufacturer were able to certify a new vehicle to the
proposed new stringent standards, the manufacturer's ability to
maintain the emission performance of that vehicle in-use is greatly
jeopardized if the vehicle is being operated on gasoline sulfur levels
greater than 10 ppm. Vehicle manufacturers, both individually and
through their trade associations, have emphasized that reduced gasoline
sulfur would be required to meet the proposed
standards.13 14 Due to the variation in actual vehicle
operation, any amount of gasoline sulfur will deteriorate catalyst
efficiency. However, we believe that a 10-ppm average sulfur level is
sufficiently low to enable compliance with these proposed Tier 3
vehicle standards, and as described below and in Section V, reducing
sulfur levels further would cause sulfur control costs to quickly
escalate.
---------------------------------------------------------------------------

    \13\ Letter to EPA Administrator Jackson, with white paper, from
Alliance of Automobile Manufacturers, October 6, 2011.
    \14\ Global Automakers letter to EPA Administrator Jackson,
October 21, 2011.
---------------------------------------------------------------------------

    The proposed FTP and SFTP NMOG+NOX standards would be
fleet-average standards, meaning that a manufacturer would calculate
the average emissions of the vehicles it sells in each model year and
compare that average to the applicable standard for that model year.
The manufacturer would certify each of its vehicles to a per-vehicle
``bin'' standard (see Section IV.A.2) and sales-weight these values to
calculate its fleet-average NMOG+NOX emissions for each
model year. The proposed fleet average standards for
NMOG+NOX evaluated over the FTP are summarized in Table I-1.
The standards for light-duty vehicles would begin in MY 2017 at a level
representing a 46 percent reduction from the current Tier 2
requirements. (For vehicles over 6000 lbs GVWR, the standards would
apply beginning in MY 2018). As shown, these proposed fleet-average
standards would decline during the first several years of the program,
becoming increasingly stringent until ultimately reaching an 81 percent
reduction when the transition is complete. The proposed FTP
NMOG+NOX program includes two separate sets of declining
fleet-average standards, with LDVs and small light trucks (LDT1s) in
one grouping and heavier light trucks (LDT2s, LDT3s, LDT4s) and MDPVs
in a second grouping, that would converge at 30 milligram per mile (mg/
mi) in MY 2025 and later.\15\
---------------------------------------------------------------------------

    \15\ Alternatively, a manufacturer could choose to certify its
entire fleet of passenger cars and light trucks to the 30 mg/mi
level beginning in MY 2017 and continuing for all subsequent model
years. A percent phase-in would apply. This would not be a fleet-
average standard.
---------------------------------------------------------------------------

    Manufacturers could also earn credits for fleet average
NMOG+NOX levels below the applicable standard in any model
year. Credits that were previously banked or obtained from other
manufacturers could be used, or credits could be transferred to other
manufacturers (see Section IV.A.7.a). Unused credits would expire after
5 model years. Manufacturers would also be allowed to carry deficits in
their credit balance for up to 3 model years.

                                       Table I-1--Proposed LDV, LDT, and MDPV Fleet Average NMOG+NOX FTP Standards
                                                                         [mg/mi]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Model year
                                                      --------------------------------------------------------------------------------------------------
                                                                                2025 and
                                                        2017 \a\     2018       2019       2020       2021       2022       2023       2024      later
--------------------------------------------------------------------------------------------------------------------------------------------------------
LDV/LDT1 \b\.........................................         86         79         72         65         58         51         44         37         30
LDT2,3,4 and MDPV....................................        101         92         83         74         65         56         47         38         30
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ For vehicles above 6000 lbs GVWR, the fleet average standards would apply beginning in MY 2018.
\b\ These proposed standards would apply for a 150,000 mile useful life. Manufacturers could choose to certify all of their LDVs and LDT1s to a useful
  life of 120,000 miles. If any of these families are certified to the shorter useful life, a proportionally lower numerical fleet-average standard
  would apply, calculated by multiplying the respective 150,000 mile standard by 0.85 and rounding to the nearest mg. See Section IV.A.7.b.

    Similarly, the proposed NMOG+NOX standards measured over
the SFTP would be fleet-average standards, declining from MY 2017 until
MY 2025, as shown in Table I-2. In this case, the same standards would
apply to both lighter and heavier vehicles. In MY 2025, the SFTP
NMOG+NOX standard would reach its final fleet average level
of 50 mg/mi.

                                      Table I-2--Proposed LDV, LDT, and MDPV Fleet Average NMOG+NOX SFTP Standards
                                                                         [mg/mi]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Model year
                                                      --------------------------------------------------------------------------------------------------
                                                                                2025 and
                                                        2017 \a\     2018       2019       2020       2021       2022       2023       2024      later
--------------------------------------------------------------------------------------------------------------------------------------------------------
NMOG + NOX...........................................        103         97         90         83         77         70         63         57         50
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ For vehicles above 6000 lbs GVWR, the fleet average standards would apply beginning in MY 2018.

    We are also proposing PM standards as part of this Tier 3 program,
both on the FTP and US06 cycles (US06 is a component of the SFTP test).
Research has demonstrated that the level of PM from gasoline light-duty
vehicles is more significant than previously thought.\16\ Although many
vehicles today are performing at or near the levels of the proposed
standards, the data indicate that improvements, especially in high-load
fuel control and in the durability of engine components, are possible.
---------------------------------------------------------------------------

    \16\ Nam, E.; Fulper, C.; Warila, J.; Somers, J.; Michaels, H.;
Baldauf, R.; Rykowski, R.; and Scarbro, C. (2008). Analysis of
Particulate Matter Emissions from Light-Duty Gasoline Vehicles in
Kansas City, EPA420-R-08-010. Assessment and Standards Division
Office of Transportation and Air Quality U.S. Environmental
Protection Agency Ann Arbor, MI, April 2008.
---------------------------------------------------------------------------

    Under typical driving, as simulated by the FTP, the PM emissions of
most current-technology gasoline vehicles are fairly low at
certification and in use, well below the Tier 2 p.m. standards. At the
same time we see considerable variation in PM emissions among vehicles
of various makes, models, and designs. As a result, we are proposing a
new FTP PM standard that is set to ensure that all new vehicles perform
at the level already being achieved by well-designed Tier 2 emission
control technologies. The proposed PM standards would apply to each
vehicle separately (i.e., not as a fleet average). Also, in contrast to
the declining NMOG+NOX standards, the proposed PM standard
on the FTP for certification testing is 3 mg/mi for all vehicles and
for all model years. As for the NMOG+NOX standards, for
vehicles over 6000 lbs GVWR, the FTP PM standard would apply beginning
in MY 2018. Manufacturers could phase in their vehicle models as a
percent of U.S. sales through MY 2022. Most vehicles are already
performing at this stringent PM level, and the primary intent of the
proposed standard is to bring all light-duty vehicles to the typical
level of PM performance being demonstrated by the current light-duty
fleet.
    The proposed program also includes a separate in-use FTP PM
standard of 6 mg/mi for the testing of in-use vehicles that would apply
during the percent phase-in period only. This in-use standard would
address the uncertainties that accompany the introduction of new
technologies, and then expire. Table I-3 presents the FTP certification
and in-use PM standards and the phase-in percentages. The proposed
standards represent a significant numerical reduction from the Tier 2
p.m. emission standards of 10 mg/mi for light-duty vehicles.

                                Table I-3--Phase-In for Proposed FTP PM Standards
----------------------------------------------------------------------------------------------------------------
                                                                                2022 and
                                                 2017 \a\     2018       2019       2020       2021      later
----------------------------------------------------------------------------------------------------------------
Phase-In (percent of U.S. sales)..............         20         20         40         70        100        100
Certification Standard (mg/mi)................          3          3          3          3          3          3

In-Use Standard (mg/mi).......................          6          6          6          6          6          3
----------------------------------------------------------------------------------------------------------------
\a\ For vehicles above 6000 lbs GVWR, the proposed FTP PM standards would apply beginning in MY 2018.

    Finally, the proposed Tier 3 program includes certification PM
standards evaluated over the SFTP (specifically the US06 component of
the SFTP procedure) at a level of 10 mg/mi for lighter vehicles and 20
mg/mi for heavier vehicles. PM levels over the SFTP are typically
higher than the PM emitted over the FTP due to the increased load on
the vehicle. Test data show that most current light-duty vehicles are
already performing in the range of the proposed standard. As in the
case of the FTP PM standards, the intent of the proposed standard is to
bring the emission performance of all vehicles to that already being
demonstrated by many vehicles in the current light-duty fleet.
    As with the FTP PM standard, we propose separate in-use US06 p.m.
standards during the percent phase-in only, of 15 and 25 mg/mi for
vehicles up to and above 6,000 lbs (lbs) GVWR, respectively. The US06
p.m. standards would also phase in on the same schedule as the FTP PM
standards, reaching 100 percent of each company's U.S. sales by MY
2022.
2. Proposed Heavy-Duty Vehicle Tailpipe Emissions Standards
    As discussed in detail in Section IV.B, we are proposing Tier 3
exhaust emissions standards for complete heavy-duty vehicles (HDVs)
between 8,501 and 14,000 lb GVWR. Vehicles in this GVWR range are often
referred to as Class 2b (8,501-10,000 lb) and Class 3 (10,001-14,000
lb) vehicles, and are typically full-size pickup trucks and work vans.
Most are built by companies with even larger light-duty truck markets,
and as such they frequently share major design characteristics and
potential emissions control technologies with their LDT counterparts.
However, in contrast to the largely gasoline-fueled LDT fleet, roughly
half of the HD pickup and van fleet in the U.S. is diesel-fueled, which
is a consideration in setting emissions standards, as diesel engine
emissions and control strategies differ from those of gasoline engines.
    The key elements of the proposed Tier 3 program for HDVs would
parallel those proposed for passenger cars and LDTs, with adjustments
in standards levels, emissions test requirements, and implementation
schedules, appropriate to this sector. These key elements include a
combined NMOG+NOX declining fleet average standard, new
stringent PM standards phasing in on a separate schedule, adoption of a
15 percent ethanol by volume (E15) certification test fuel for
gasoline-fueled vehicles, extension of the regulatory useful life to
150,000 miles or 15 years (whichever occurs first), and a new
requirement to meet standards over an SFTP that would address real-
world driving modes not well-represented by the FTP cycle alone.
    We are proposing the separate Class 2b and Class 3 fleet average
NMOG+NOX standards shown in Table I-4. The proposed
standards would become more stringent in successive model years from
2018 to 2022, with voluntary standards made available in 2016 and 2017,
all of which would be set at levels that match those of California's
LEV III program for these classes of vehicles. Each covered HDV sold by
a manufacturer in each model year would contribute to this fleet
average based on the mg/mi NMOG+NOX level of the emission
level (``bin'') declared for it by the manufacturer. Manufacturers
could also earn credits for fleet average NMOG+NOX levels
below the standard in any model year. Tier 3 credits that were
previously banked, obtained from other manufacturers, or transferred
across the Class 2b/Class 3 categories could be used to help
demonstrate compliance. Unused credits would expire after 5 model
years. Manufacturers would also be allowed to carry deficits in their
credit balance for up to 3 model years.

                                                Table I-4--Proposed HDV Fleet Average NMOG+NOX Standards
                                                                         [mg/mi]
--------------------------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                     Voluntary
                                                                 Required program.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Model Year...................................       2016       2017       2018       2019       2020       2021  2022 and later.
Class 2b.....................................        333        310        278        253        228        203  178.
Class 3......................................        548        508        451        400        349        298  247.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    We are proposing PM standards of 8 mg/mi and 10 mg/mi for Class 2b
and Class 3 HDVs, respectively, phasing in as an increasing percentage
of a manufacturer's sales per year. We are proposing the same phase-in
schedule as proposed for the light-duty sector during model years 2018-
2019-2020-2021: 20-40-70-100 percent, respectively, and a more flexible
but equivalent alternative PM phase-in is also being proposed. Tier 3
HDVs would also be subject to more stringent CO and formaldehyde
exhaust emissions standards.
    Finally, we are proposing first-ever SFTP standards for HDVs to
ensure a robust overall control program that precludes high off-FTP
cycle emissions by having vehicle designers consider them in their
choice of compliance strategies. As for light-duty vehicles, we are
proposing that SFTP compliance be based on a weighted composite of
measured emissions from testing over the FTP cycle, the SC03 cycle, and
an aggressive driving cycle, with the latter tailored to various HDV
sub-categories: the US06 cycle for most HDVs, the highway portion of
the US06 cycle for low power-to-weight Class 2b HDVs, and the LA-92 (or
``Unified'') cycle for Class 3 HDVs. The proposed SFTP standards are
the same as those adopted for California LEV III vehicles, and would
apply to NMOG+NOX, PM, and CO emissions.
    Overall, we expect the Tier 3 program we are proposing for HDVs to
result in

substantial reductions in harmful emissions from this large fleet of
work trucks and vans. The final Tier 3 standards levels for
NMOG+NOX and PM are on the order of 60 percent lower than
the current stringent standards that took full effect in the 2009 model
year.
3. Proposed Evaporative Emission Standards
    Gasoline vapor emissions from vehicle fuel systems occur when a
vehicle is in operation, when it is parked, and when it is being
refueled. These evaporative emissions, which occur on a daily basis
from gasoline-powered vehicles, are primarily functions of temperature,
fuel vapor pressure, and activity. EPA first instituted evaporative
emission standards in the early 1970s to address emissions when
vehicles are parked after being driven. These are commonly referred to
as hot soak plus diurnal emissions. Over the subsequent years the test
procedures have been modified and improved and the standards have
become more numerically stringent. We have addressed emissions which
arose from new fuel system designs by putting in place new requirements
such as running loss emission standards and test procedure provisions
to address permeation emissions. Subsequently standards were put in
place to control refueling emissions from all classes of gasoline-
powered motor vehicles up to 10,000 lbs GVWR. Even though evaporative
and refueling emission control systems have been in place for most of
these vehicles for many years, they still contribute about 30-40
percent of the summer on-highway mobile source hydrocarbon inventory.
These fuel vapor emissions are ozone and PM precursors, and also
contain air toxics such as benzene.
    To control evaporative emissions, EPA is proposing more stringent
standards that would require covered vehicles to have essentially zero
fuel vapor emissions in use. These include more stringent evaporative
emissions standards, new test procedures, and a new fuel/evaporative
system leak emission standard. The program also includes refueling
emission standards for a portion of heavy-duty gasoline vehicles
(HDGVs) over 10,000 lbs GVWR. EPA is proposing phase-in flexibilities
as well as credit and allowance programs. The proposed standards,
harmonized with California's ``zero evap'' standards, are designed to
essentially allow for a use of common technology in vehicle models sold
throughout the U.S. The level of the standard remains above zero to
account for nonfuel background emissions from the vehicle hardware
itself.
    Requirements to meet the Tier 3 evaporative emission regulations
would phase-in over a six model year period. We are proposing two
options for the 2017 model year, but after that the sales percentage
requirements are 60 percent for MYs 2018 and 2019, 80 percent for model
years 2020 and 2021, and 100 percent for model years 2022 and later. In
Table I-5 we present the proposed evaporative diurnal plus hot soak
emission standards by vehicle class. The standards are approximately a
50 percent reduction from the existing standards. To enhance
flexibility and reduce costs, EPA is proposing a program that would
allow manufacturers to generate allowances through early certifications
(basically before the 2017 model year) and to demonstrate compliance
using averaging concepts. Manufacturers may comply on average within
each of the four vehicle categories, but not across these categories.
EPA is not proposing any changes to the existing light-duty running
loss or refueling emission standards, with the exception of the
certification test fuel requirement discussed in Section I.B.5 below.

           Table I-5--Proposed Evaporative Emission Standards
                                [g/test]
------------------------------------------------------------------------
                                                  Highest diurnal + hot
                                                  soak level  (over both
                 Vehicle class                   2-day and 3-day diurnal
                                                          tests)
------------------------------------------------------------------------
LDV, LDT1......................................                    0.300
LDT2...........................................                    0.400
LDT3, LDT4, MDPV...............................                    0.500
HDGVs..........................................                    0.600
------------------------------------------------------------------------

    EPA is proposing a new testing requirement referred to as the bleed
emission test procedure to help ensure fuel vapor emissions are
eliminated. Under this proposal, manufacturers would be required to
measure diurnal emissions over the 2-day diurnal test procedure from
just the fuel tank and the evaporative emission canister and comply
with a 0.020 gram per test (g/test) standard for all LDVs, LDTs, and
MDPVs, without averaging. The corresponding canister bleed test
standard for HDGVs would be 0.030 g/test. The proposed Tier 3
evaporative emission standards would be phased in over a period of six
model years between MY 2017 and MY 2022, with the leak test phasing in
beginning in 2018.
    Data from in-use evaporative emissions testing indicates that vapor
leaks from vehicle fuel/evaporative systems are found in the fleet and
that even very small leaks have the potential to make relatively
significant contributions to the mobile source VOC inventory. To help
address this issue, we are also proposing to add a new emission
standard and test procedure to control vapor leaks from vehicle fuel
and vapor control systems. The standard would prohibit leaks with a
cumulative equivalent diameter of 0.02 inches or greater. We are
proposing to add this simple and inexpensive test and emission standard
to help ensure vehicles maintain zero fuel vapor emissions over their
full useful life. New LDV, LDT, MDPV, and HDGV equal to or less than
14.000 lbs GVWR meeting the proposed Tier 3 evaporative emission
regulations would also be required to meet the leak emission standard
beginning in the 2018 model year. The requirement to meet the leak
emission standard would phase-in on the same percentage of sales
schedule as the proposed Tier 3 evaporative emission standard.
Manufacturers would comply with the leak emission standard during
certification and in use. EPA is not proposing that the leak emission
standard apply to HDGVs above 14,000 lbs GVWR.
    EPA is also proposing new refueling emission control requirements
for all HDGVs equal to or less than 14,000 lbs GVWR (i.e., Class 2b/3
HDGVs), starting in the 2018 model year. EPA is proposing to include
these vehicles as part of the same basic implementation scheme used for
LDVs and LDTs. The current refueling emission control requirements
apply to complete Class 2b HDGVs, and EPA is proposing to extend those
requirements to Class 3 HDGVs as well, since the fuel and evaporative
control systems on these vehicles are very similar to those on their
slightly lighter-weight Class 2b counterparts.
4. Onboard Diagnostic Systems (OBD)
    EPA and CARB both have OBD regulations applicable to the vehicle
classes covered by the proposed Tier 3 emission standards. In the past
the requirements have been very similar, so most manufacturers have met
CARB OBD requirements and, as permitted in our regulations, EPA has
generally accepted compliance with CARB's OBD requirements as
satisfying EPA's OBD requirements. Over the past several years CARB has
upgraded its requirements to help improve the effectiveness of OBD in
ensuring good in-use exhaust and evaporative system emissions
performance. We have reviewed these provisions and agree with CARB that
these revisions will

help to improve in-use emissions performance, while at the same time
harmonizing with the CARB program. Toward that end, we are proposing to
adopt and incorporate by reference the current CARB OBD regulations
effective for the 2017 MY. We are also proposing two specific additions
to enhance the implementation of the leak emission standard. EPA would
retain the provision that certifying with CARB's program would permit
manufacturers to seek a separate EPA certificate on that basis.
5. Emissions Test Fuel
    In-use gasoline has changed considerably since EPA's test fuel
specifications were first set and last revised. Gasoline sulfur and
benzene have been reduced and, perhaps most importantly, gasoline
containing 10 percent ethanol by volume (E10) has replaced clear
gasoline (E0) across the country. This has had second-order effects on
other gasoline properties. In-use fuel is projected to continue to
change with the implementation of the RFS2 program (e.g., the potential
expansion of the number of retailers that offer gasoline containing 15
percent ethanol by volume (E15)) as well as today's proposed Tier 3
gasoline sulfur program.
    As a result, we are proposing to update our federal emissions test
fuel to better match today's in-use gasoline and also to be forward-
looking with respect to future ethanol and sulfur content. The new test
fuel specifications would apply to new vehicle certification, assembly
line, and in-use testing. EPA is also proposing changes consistent with
CARB's LEV III emissions test fuel specifications. Key changes include:
     Moving away from ``Indolene'' (E0) to an E15 test fuel;
     Lowering octane to match regular-grade gasoline (except
for premium-required vehicles);
     Adjusting distillation temperatures, aromatics, and
olefins to better match today's in-use fuel and to be consistent with
anticipated E15 composition; and
     Lowering the existing sulfur specification and setting a
benzene specification to be consistent with proposed Tier 3 gasoline
sulfur requirements and recent MSAT2 gasoline benzene requirements.\17\
---------------------------------------------------------------------------

    \17\ 72 FR 8434 (February 26, 2007).
---------------------------------------------------------------------------

    The proposed E15 emissions test fuel specifications are detailed in
Section IV.D.1 as well as Sec.  1065.710 of the proposed regulations.
For more information on how we arrived at the proposed fuel parameters
and ASTM test methods, refer to Chapter 3 of the draft Regulatory
Impact Analysis (RIA).
    In addition to proposing a new E15 emissions test fuel, we are also
proposing for the first time detailed specifications for the E85
emissions test fuel used for flexible fuel vehicle (FFV) certification,
as discussed in Section IV.D.2.\18\ This is intended to avoid
uncertainty and confusion in the certification of FFVs designed to
operate on ethanol levels up to 83 percent. Furthermore, we are
proposing to allow vehicle manufacturers to request approval for an
alternative certification fuel such as a high-octane 30 percent ethanol
by volume (E30) blend for vehicles they might design or optimize for
use on such a fuel. This could help manufacturers that wish to raise
compression ratios to improve vehicle efficiency, as a step toward
complying with the 2017 and later light-duty greenhouse gas and CAFE
standards (2017 LD GHG). This in turn could help provide a market
incentive to increase ethanol use beyond E10 by overcoming the
disincentive of lower fuel economy associated with increasing ethanol
concentrations in fuel, and enhance the environmental performance of
ethanol as a transportation fuel by using it to enable more fuel
efficient engines.
---------------------------------------------------------------------------

    \18\ Flexible fuel vehicles are currently required to meet
emissions certification requirements using both E0 and E85 test
fuels. However, there are currently no detailed regulatory
specifications regarding the composition of E85 test fuels.
---------------------------------------------------------------------------

    In addition to seeking comment on all aspects of the proposed new
emission test fuel requirements, we also seek comment on whether there
are other aspects of today's proposed standards that, if modified,
might provide an incentive for, or remove obstacles to, the development
of highly efficient vehicles optimized for use on higher level ethanol
blends.
6. Fuel Standards
    Under the Tier 3 fuel program, we are proposing that gasoline and
any ethanol-gasoline blend contain no more than 10 ppm sulfur on an
annual average basis by January 1, 2017. Similar to the Tier 2 gasoline
program, the proposed Tier 3 program would apply to gasoline in the
U.S. and the U.S. territories of Puerto Rico and the Virgin Islands,
excluding California. The proposed program would result in gasoline
that contains, on average, two-thirds less sulfur than it does today.
In addition, following discussions with numerous refiners and other
segments of the fuel market (e.g., pipelines, terminals, marketers,
ethanol industry representatives, transmix processors, additive
manufacturers), we are proposing a Tier 3 fuel program that contains
considerable flexibility to ease both initial and long-term
implementation of the program. We are proposing an averaging, banking,
and trading (ABT) program that would allow refiners and importers to
spread out their investments through an early credit program and rely
on ongoing nationwide averaging to meet the 10-ppm sulfur standard. We
are also proposing a three-year delay for small refiners and ``small
volume refineries'' processing less than or equal to 75,000 barrels of
crude oil per day. As a result of the early credit program, even
considering the proposed ABT program and flexibilities offered to small
refiners and small volume refineries, we anticipate considerable
reductions in gasoline sulfur levels prior to 2017, with final refinery
control to the 10-ppm average occurring by January 1, 2020. For more on
the proposed gasoline sulfur program flexibilities, refer to Section
V.D.
    Under today's Tier 3 gasoline sulfur program, we are proposing to
either maintain the current 80-ppm refinery gate and 95-ppm downstream
per-gallon caps or lower them to 50 and 65 ppm, respectively. We also
evaluated and are seeking comment on the potential of lowering the per-
gallon caps to as low as 20 and 25 ppm. There are advantages and
disadvantages with each of the various sulfur cap options (explained in
more detail in Section V.A.3), but under all scenarios, the stringency
of the 10-ppm annual average standard would result in reduced gasoline
sulfur levels nationwide. A summary of the proposed Tier 3 sulfur
standards is provided in Table I-6.

                                                  Table I-6--Proposed Tier 3 Gasoline Sulfur Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Cap Option 1                                                Cap Option 2
Proposed Tier 3 gasoline sulfur ------------------------------------------------------------------------------------------------------------------------
           standards                         Limit                        Effective                       Limit                       Effective
--------------------------------------------------------------------------------------------------------------------------------------------------------
Refinery annual average          10 ppm.......................  January 1, 2017 \a\.........  10 ppm......................  January 1, 2017.\a\
 standard.
Refinery gate per-gallon cap...  80 ppm.......................  Already.....................  50 ppm......................  January 1, 2020.
Downstream per-gallon cap......  95 ppm.......................  Already.....................  65 ppm......................  March 1, 2020.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Effective January 1, 2020 for eligible small refiners and small volume refineries.

    We are proposing that manufacturers of gasoline additives that are
used downstream of the refinery at less than 1 volume percent must
limit the sulfur contribution to the finished gasoline from the use of
their additive to less than 3 ppm when the additive is used at the
maximum recommended treatment rate.
    The proposed vehicle emissions standards are fuel neutral (i.e.
they are applicable regardless of the type of fuel that the vehicle is
designed to use). The sulfur content of highway diesel fuel is already
required to meet a 15ppm sulfur cap. Thus, no further action is needed
to enable diesel fuel vehicles to meet the proposed emissions
standards. There currently are no sulfur standards for the fuel used in
compressed natural gas (CNG) and liquid propane gas (LPG) vehicles. We
request comment on whether it is necessary for EPA to establish sulfur
standards for CNG and LPG, and whether a 15 ppm sulfur cap similar to
that established for highway diesel fuel would be appropriate. Comment
is also requested on whether and how to address the sulfur contribution
from odorants and other additives used in CNG and LPG.
    As the number of flex-fuel vehicles (FFVs) in the in-use fleet
increases, it is now becoming increasingly important that all fuels
used in FFVs, not just gasoline, meet fuel quality standards. A lack of
clarity regarding the standards that apply to fuels used in FFVs could
act to impede the further expansion of ethanol blended fuels with
concentrations greater than 15 volume percent, which is important to
satisfying the requirements of the RFS2 program. For these reasons, we
believe it is important that our gasoline quality standards for not
only sulfur, but also benzene, RVP, detergency, and chemical
composition (i.e., contains only carbon, hydrogen, oxygen, nitrogen,
and sulfur) apply to any fuel used in an FFV. At the same time, it is
not necessarily clear how we should implement such standards within the
context of our existing regulations as these fuels tend to be produced
downstream of the petroleum refinery. For this reason we are seeking
comment on both the need to extend our gasoline standards to all
gasoline-ethanol blends, as well as the appropriate regulatory
mechanisms for doing so.
7. Regulatory Streamlining and Technical Amendments
    We are proposing and requesting comment in this action on a number
of items to help streamline the in-use fuels regulations at 40 CFR part
80. The majority of items involve clarifying vague or inconsistent
language, removal or updating of outdated provisions, and decrease in
frequency and/or volume of reporting burden where data are no longer
needed or are redundant with other EPA fuels programs. In general, we
believe that these changes would reduce burden on industry and allow us
to achieve the standards and resulting environmental benefits as early
as possible with no expected loss in environmental control. In some
cases, these regulatory streamlining items are non-substantive
amendments that correct minor errors or inconsistencies in the
regulations.
    The regulatory streamlining items that we are proposing for the in-
use fuels regulations are changes that we believe are straightforward
and should be made quickly. In addition, there are a number of items
that we believe need further consideration and discussion on which we
are seeking comment.
    The proposal also includes a variety of technical amendments to
certification-related requirements for engine and vehicle emission
standards. We are proposing to revise the fuel economy labeling
requirements to correspond to the new Tier 3 standards. We are also
proposing to remove obsolete regulatory text and make several minor
corrections and clarifications.
    Please refer to Section VI for a complete discussion of technical
amendments and regulatory streamlining provisions and issues.

C. What would the impacts of the proposed standards be?

    The proposed Tier 3 vehicle and fuel standards together would
reduce dramatically emissions of NOX, VOC, PM2.5,
and air toxics. The gasoline sulfur standards, which would take effect
in 2017, would provide large immediate reductions in emissions from
existing gasoline vehicles and engines. NOX emissions would
be reduced by about 284,000 tons, or about 8 percent of emissions from
on-highway vehicles, in 2017 alone. The emission reductions would
increase over time as newer vehicles become a larger percentage of the
fleet. In 2030, when 80 percent of the light-duty fleet (and 90 percent
of the vehicle miles travelled) consists of Tier 3 vehicles, we expect
the NOX and VOC emissions to be reduced by about 525,000
tons and 226,000 tons, respectively, or one quarter of emissions from
on-highway vehicles compared to their 2030 levels without the Tier 3
program. Emissions of CO would decrease by almost 6 million tons, or 30
percent of emissions from on-highway vehicles. Emissions of many air
toxics would also be reduced, including benzene, 1,3-butadiene,
acetaldehyde, formaldehyde, acrolein and ethanol, with reductions
ranging from 10 to nearly 40 percent of national emissions from on-
highway vehicles. We expect these reductions to continue beyond 2030 as
more of the fleet continues to turn over to Tier 3 vehicles; for
example, by 2050, when nearly all of the fleet would have turned over
to Tier 3 standards, we estimate the Tier 3 program would reduce on-
highway emissions of NOX and VOC nearly 40 percent from the
level of emissions projected without Tier 3 controls.\19\
---------------------------------------------------------------------------

    \19\ To estimate the benefits of the proposed Tier 3 rule, we
perfomed air quality modeling for the year 2030.
---------------------------------------------------------------------------

    These reductions in emissions of NOX, VOC,
PM2.5 and air toxics from the proposed Tier 3 standards are
projected to lead to significant decreases in ambient concentrations of
ozone, PM2.5 and air toxics (including notable nationwide
reductions in benzene concentrations) by 2030, and would immediately
reduce ozone in 2017 when the proposed sulfur controls take effect.
Additional information on the emission and air quality impacts of the
proposed Tier 3 program is presented in Sections III.B and C.

    Exposure to ambient concentrations of ozone, PM2.5, and
air toxics is linked to adverse human health impacts such as premature
deaths as well as other important public health and environmental
effects (see Section II.B). The proposed Tier 3 standards would reduce
these adverse impacts and yield significant benefits, including those
we can monetize and those we are unable to quantify. We estimate that
by 2030, the annual emission reductions of the Tier 3 standards would
annually prevent between 670 and 1,700 PM-related premature deaths,
between 160 and 710 ozone-related premature deaths, 81,000 work days
lost, and approximately 1.4 million minor restricted-activity days. The
estimated annual monetized health benefits of the proposed Tier 3
standards in 2030 (2010$) would be between $8.0 and $23 billion,
assuming a 3-percent discount rate (or between $7.4 billion and $21
billion assuming a 7-percent discount rate). \20\ The proposed fuel
standards are projected to cost on average less than one cent per
gallon of gasoline, and the proposed light-duty vehicle standards would
have an average cost that increases in proportion to the increase in
stringency from $50 per vehicle in 2017 to $134 per vehicle when the
standards are fully phased in 2025. The annual cost of the overall
program in 2030 would be approximately $3.4 billion.\21\ The 2030
benefits are 2 to 7 times the costs of the program.
---------------------------------------------------------------------------

    \20\ These benefits estimates have been adjusted to remove
benefits of the Tier 3 program in California. The Tier 3 proposal's
analysis assumed emissions reductions and resulting benefits would
occur nationwide. California was recently granted a Clean Air Act
waiver of preemption for the LEV III vehicle program, and some other
states have adopted it. The Tier 3 final rule analysis will account
for those emission reductions that will occur even in the absence of
Tier 3 vehicle standards, for all states that have adopted LEV III.
See Section VIII of the preamble for more information on the
benefits associated with the Tier 3 program.
    \21\ Costs include estimates for the proposed Tier 3 standards
in all states except California.
---------------------------------------------------------------------------

    The benefits in Table I-7 include all of the human health impacts
we are able to quantify and monetize at this time. However, the full
complement of human health and welfare effects associated with PM,
ozone and air toxics remain unquantified because of current limitations
in methods and/or available data. As a result, the health benefits
quantified in this section are likely underestimates of the total
benefits attributable to the proposed standards. See Sections VII and
VIII for detailed descriptions of the costs and benefits of this
proposal.

   Table I-7--Summary of Annual Benefits and Costs Associated With the
                         Proposed Tier 3 Program
                          [Billions, 2010$] \a\
------------------------------------------------------------------------
                       Description                             2030
------------------------------------------------------------------------
Vehicle Program Costs...................................            $2.1
Fuels Program Costs.....................................             1.3
Total Estimated Costs \b\...............................             3.4
Total Estimated Health Benefits c d e f g...............  ..............
    3 percent discount rate.............................        $8.0-$23
    7 percent discount rate.............................          7.4-21
Annual Net Benefits (Total Benefits--Total Costs):......  ..............
    3 percent discount rate.............................          4.6-20
    7 percent discount rate.............................          4.0-18
------------------------------------------------------------------------
\a\ All estimates represent annual benefits and costs anticipated for
  the year 2030. Totals are rounded to two significant digits and may
  not sum due to rounding.
\b\ The calculation of annual costs does not require amortization of
  costs over time. Therefore, the estimates of annual cost do not
  include a discount rate or rate of return assumption (see Section VII
  of the preamble for more information on vehicle and fuel costs). The
  program costs include the costs associated with the Tier 3 vehicle and
  fuel standards in all states except California.
\c\ The benefits presented in this table have been adjusted to remove
  benefits of the Tier 3 program in California.
\d\ Total includes ozone and PM2.5 benefits. Range was developed by
  adding the estimate from the Bell et al., 2004 ozone premature
  mortality function to PM2.5-related premature mortality derived from
  the American Cancer Society cohort study (Pope et al., 2002) for the
  low estimate and ozone premature mortality derived from the Levy et
  al., 2005 study to PM2.5-related premature mortality derived from the
  Six-Cities (Laden et al., 2006) study for the high estimate.
\e\ Annual benefits analysis results reflect the use of a 3 percent and
  7 percent discount rate in the valuation of premature mortality and
  nonfatal myocardial infarctions, consistent with EPA and OMB
  guidelines for preparing economic analyses.
\f\ Valuation of premature mortality based on long-term PM exposure
  assumes discounting over the SAB recommended 20-year segmented lag
  structure described in the Regulatory Impact Analysis for the 2006 PM
  National Ambient Air Quality Standards (September, 2006).
\g\ Not all possible benefits are quantified and monetized in this
  analysis; the total monetized benefits presented here may therefore be
  underestimated. Potential benefit categories that have not been
  quantified and monetized, due to current limitations in methods and/or
  data availability, are listed in Table VIII-2. For example, we have
  not quantified a number of known or suspected health and welfare
  effects linked with reductions in ozone and PM (e.g., reductions in
  heart rate variability, reduced material damage to structures and
  cultural monuments, and reduced eutrophication in coastal areas). We
  are also unable to quantify health and welfare benefits associated
  with reductions in air toxics.

II. Why is EPA making this proposal?

    The Clean Air Act authorizes EPA to establish emissions standards
for motor vehicles to address air pollution that may reasonably be
anticipated to endanger public health or welfare. EPA also has
authority to establish fuel controls to address such air pollution.
These statutory requirements are described in Section II.A.
    Emissions from motor vehicles and their fuels contribute to ambient
levels of ozone, PM, NO2, sulfur dioxide (SO2)
and CO, which are all pollutants for which EPA has established health-
based NAAQS. These pollutants are linked with respiratory and/or
cardiovascular problems and other adverse health impacts leading to
increased medication use, hospital admissions, emergency department
visits, and premature mortality. Over 158 million people currently live
in areas designated nonattainment for one or more of the current
NAAQS.\22\
---------------------------------------------------------------------------

    \22\ Data come from Summary Nonattainment Area Population
Exposure Report, current as of December 14, 2012 at: http://www.epa.gov/oar/oaqps/greenbk/popexp.html and contained in Docket
EPA-HQ-OAR-2011-0135.
---------------------------------------------------------------------------

    Motor vehicles also emit air toxics, and the majority of Americans
continue to be exposed to ambient concentrations of air toxics at
levels which have the potential to cause adverse health effects,
including cancer, immune system damage, and neurological, reproductive,
developmental, respiratory, and other

health problems.\23\ A more detailed discussion of the health and
environmental effects of these pollutants is included in Section II.B.
---------------------------------------------------------------------------

    \23\ U.S. EPA. (2011) Summary of Results for the 2005 National-
Scale Assessment. www.epa.gov/ttn/atw/nata2005/05pdf/sum_results.pdf.
---------------------------------------------------------------------------

    Cars and light trucks also continue to be a significant contributor
to air pollution directly near roads, with gasoline vehicles accounting
for more than 50 percent of near-road concentrations of some criteria
and toxic pollutants.\24\ More than 50 million people live, work, or go
to school in close proximity to high-traffic roadways, and the average
American spends more than one hour traveling each day, with nearly 90
percent of daily trips occurring by personal
vehicle.25 26 27 Exposure to traffic-related pollutants has
been linked with adverse health impacts such as respiratory problems
(particularly in asthmatic children) and cardiovascular problems.
---------------------------------------------------------------------------

    \24\ For example, see Fujita, E.M; Campbell, D.E.; Zielinska,
B.; Arnott, W.P.; Chow, J.C. (2011) Concentrations of Air Toxics in
Motor Vehicle-Dominated Environments. Health Effects Institute
Research Report 156. Available at http://www.healtheffects.org.
    \25\ U.S. Census Bureau (2011). Current Housing Reports, Series
H150/09, American Housing Survey for the United States: 2009. U.S.
Government Printing Office, Washington, DC. Available at http://www.census.gov/hhes/www/housing/ahs/ahs09/ahs09.html.
    \26\ Drago, R.(2011). Secondary activities in the 2006 American
Time Use Survey. U.S. Bureau of Labor Statistics Working Paper 446.
Available at http://www.bls.gov.
    \27\ U.S. Department of Transportation, Bureau of Transportation
Statistics. (2003) National Household Travel Survey 2001 Highlights
Report. Government Printing Office, Washington, DC. Available at
http://www.bts.gov/publications/highlights_of_the_2001_national_household_travel_survey/.
---------------------------------------------------------------------------

    In the absence of additional controls such as Tier 3 standards,
many areas will continue to have ambient ozone and PM2.5
concentrations exceeding the NAAQS in the future. States and local
areas are required to adopt control measures to attain the NAAQS and,
once attained, to demonstrate that control measures are in place
sufficient to maintain the NAAQS for ten years (and eight years later,
a similar demonstration is required for another ten-year period). The
proposed Tier 3 standards would be a critical part of areas' strategies
to attain and maintain the standards. Maintaining the standards has
been challenging in the past, particularly for areas where high
population growth rates lead to significant annual increases in vehicle
trips and vehicle miles traveled. Our air quality modeling for this
proposal, which is described in more detail in Section III.C, projects
that in 2017 a significant number of counties outside CA will be within
10 percent of the 2008 ozone NAAQS, in the absence of additional
controls. These counties in particular would benefit from the proposed
Tier 3 standards as they work to ensure long-term maintenance of the
NAAQS.
    Section III provides more detail on how this proposal would reduce
motor vehicle emissions and ambient levels of pollution. The proposed
rule would meaningfully reduce ozone concentrations as early as 2017
(the first year of the program), and even more significantly in 2030.
The reductions are of significant enough magnitude to bring ozone
levels in some counties from above the standard to below the standard,
even without any additional controls. We also project that the Tier 3
standards would reduce ambient PM2.5 concentrations.
    Without this proposal to reduce nationwide motor vehicle emissions,
areas would have to adopt other measures to reduce emissions from other
sources under their state or local authority. Few other measures exist
for providing multi-pollutant reductions of the same magnitude and
cost-effectiveness as those expected from the proposed Tier 3
standards. Furthermore, states outside California do not have the
authority to lower the sulfur in gasoline, which is needed to
immediately reduce emissions from the existing fleet and also enable
new vehicles to meet the proposed Tier 3 emissions standards throughout
their useful life.
    The reductions in ambient ozone and PM2.5 that would
result from the proposed Tier 3 standards would provide significant
health benefits. By 2030, the standards would annually prevent between
670 and 1,700 PM-related premature deaths, between 160 and 710 ozone-
related premature deaths, 81,000 work days lost, and approximately 1.4
million minor restricted-activity days (see Section VIII for more
details). This proposal would also reduce air toxics; for example, we
project that in 2030, the proposal would decrease ambient benzene
concentrations by 10-25 percent in some urban areas. Furthermore, the
proposed Tier 3 standards would reduce traffic-associated pollution
near major roads. EPA is proposing Tier 3 vehicle and fuel standards as
part of a comprehensive nationwide program for regulating all types of
air pollution from motor vehicles. EPA recently finalized standards to
reduce GHG emissions from light-duty vehicles, starting with model year
2017.\28\ The Tier 3 standards in this proposal, which address non-
GHGs, would be implemented on the same timeframe, thus allowing
manufacturers to optimize their vehicle redesigns over both sets of
standards. Furthermore, the Tier 3 vehicle and fuel standards are also
closely aligned with California's LEV III program, in such a way that
manufacturers could design a single vehicle for nationwide sales. This
reduces the cost of compliance for auto manufacturers.
---------------------------------------------------------------------------

    \28\ 77 FR 62623 (October 15, 2012).
---------------------------------------------------------------------------

    This Tier 3 proposal responds to the President's request in his May
2010 memorandum for EPA to review the adequacy of its existing non-GHG
standards for new motor vehicles and fuels, and to promulgate new
standards, if necessary, as part of a comprehensive approach to
regulating motor vehicles.\29\ Based on our review, we have concluded
that improved vehicle technology, combined with lower sulfur gasoline,
make it feasible and cost-effective to reduce emissions well below the
current Tier 2 levels. These emission reductions are necessary to
reduce air pollution that is (and projected to continue to be) at
levels that endanger public health and welfare.
---------------------------------------------------------------------------

    \29\ The Presidential Memorandum is found at: http://www.whitehouse.gov/the-press-office/presidential-memorandum-regarding-fuel-efficiency-standards.
---------------------------------------------------------------------------

A. Basis for Action Under the Clean Air Act

1. Clean Air Act Section 202
    We are proposing to set motor vehicle emission standards under the
authority of section 202 of the Clean Air Act. Section 202(a) provides
EPA with general authority to prescribe vehicle standards, subject to
any specific limitations elsewhere in the Act. EPA is also setting
standards for larger light-duty trucks and MDPVs under the general
authority of section 202(a)(1) and under section 202(a)(3), which
requires that standards applicable to emissions of hydrocarbons,
NOX, CO and PM from heavy-duty vehicles \30\ reflect the
greatest degree of emission reduction available for the model year to
which such standards apply, giving appropriate consideration to cost,
energy, and safety. In addition, section 202(k) provides EPA with
authority to issue and revise regulations applicable to evaporative
emissions of hydrocarbons from all gasoline-fueled motor vehicles
during: (1) Operation, and (2) over 2 or more days of nonuse;

under ozone-prone summertime conditions. Regulations under section
202(k) shall take effect as expeditiously as possible and shall require
the greatest degree of emission reduction achievable by means
reasonably expected to be available for production during any model
year to which the regulations apply, giving appropriate consideration
to fuel volatility, and to cost, energy, and safety factors associated
with the application of the appropriate technology. Further, section
206 and in particular section 206(d) of the Clean Air Act authorizes
EPA to establish methods and procedures for testing whether a motor
vehicle or motor vehicle engine conforms with section 202 requirements.
---------------------------------------------------------------------------

    \30\ LDTs that have gross vehicle weight ratings above 6000 lbs
are considered ``heavy-duty vehicles'' under the CAA. See section
202(b)(3)(C). For regulatory purposes, we refer to those LDTs at or
below 8500 lbs GVWR as ``heavy light-duty trucks'' made up of LDT3s
and LDT4s.
---------------------------------------------------------------------------

2. Clean Air Act Section 211
    We are proposing to adopt gasoline sulfur controls pursuant to our
authority under section 211(c)(1) of the CAA. This section allows EPA
to establish a fuel control if at least one of the following two
criteria is met: (1) The emission products of the fuel cause or
contribute to air pollution which may reasonably be anticipated to
endanger public health or welfare; or (2) the emission products of the
fuel will impair to a significant degree the performance of any
emissions control device or system which is either in general use or
which the Administrator finds has been developed to a point where in a
reasonable time it will be in general use were the fuel control to be
adopted. We are proposing gasoline sulfur controls based on both of
these criteria. Under the first criterion, we believe that gasoline
with current levels of sulfur contributes to ambient levels of air
pollution that endanger public health and welfare, as described in
Section II.B. Under the second criterion, we believe that gasoline
sulfur impairs the emissions control systems of vehicles, as discussed
in Section III.A.2.

B. Overview of Public Health Impacts of Motor Vehicles and Fuels

    Motor vehicles emit pollutants that contribute to ambient levels of
ozone, PM, NO2, SO2, CO, and air toxics. Motor
vehicles are significant contributors to emissions of VOC and
NOX, which contribute to the formation of both ozone and
PM2.5. Approximately 159 million people currently live in
counties designated nonattainment for one or more of the NAAQS, and
this figure does not include the people living in areas with a risk of
exceeding the NAAQS in the future.\31\ The majority of Americans
continue to be exposed to ambient concentrations of air toxics at
levels which have the potential to cause adverse health effects.\32\ In
addition, populations who live, work, or attend school near major roads
experience elevated exposure concentrations to a wide range of air
pollutants.\33\
---------------------------------------------------------------------------

    \31\ Data come from Summary Nonattainment Area Population
Exposure Report, current as of July 20, 2012 at: http://www.epa.gov/oar/oaqps/greenbk/popexp.html and contained in Docket EPA-HQ-OAR-
2011-0135.
    \32\ U.S. EPA. (2011) Summary of Results for the 2005 National-
Scale Assessment. www.epa.gov/ttn/atw/nata2005/05pdf/sum_results.pdf.
    \33\ Health Effects Institute Panel on the Health Effects of
Traffic-Related Air Pollution. (2010) Traffic-related air pollution:
a critical review of the literature on emissions, exposure, and
health effects. HEI Special Report 17. Available at http://www.healtheffects.org].
---------------------------------------------------------------------------

    EPA has already adopted many emission control programs that are
expected to reduce ambient pollution levels. As a result of these
programs, the number of areas that continue to violate the ozone and
PM2.5 NAAQS or have high levels of air toxics is expected to
continue to decrease. However, the baseline air quality modeling
completed for this proposed rule predicts that without additional
controls there will continue to be a need for reductions in ozone,
PM2.5 and air toxics concentrations in the future. Section
III.C of this preamble presents the air quality modeling results for
this proposed rule.
1. Ozone
a. Background
    Ground-level ozone pollution is typically formed through reactions
involving VOC and NOX in the lower atmosphere in the
presence of sunlight. These pollutants, often referred to as ozone
precursors, are emitted by many types of pollution sources, such as
highway and nonroad motor vehicles and engines, power plants, chemical
plants, refineries, makers of consumer and commercial products,
industrial facilities, and smaller area sources.
    The science of ozone formation, transport, and accumulation is
complex. Ground-level ozone is produced and destroyed in a cyclical set
of chemical reactions, many of which are sensitive to temperature and
sunlight. When ambient temperatures and sunlight levels remain high for
several days and the air is relatively stagnant, ozone and its
precursors can build up and result in more ozone than typically occurs
on a single high-temperature day. Ozone and its precursors can be
transported hundreds of miles downwind from precursor emissions,
resulting in elevated ozone levels even in areas with low local VOC or
NOX emissions.
b. Health Effects of Ozone
    The health and welfare effects of ozone are well documented and are
assessed in EPA's 2006 Air Quality Criteria Document and 2007 Staff
Paper.34 35 People who are more susceptible to effects
associated with exposure to ozone can include children, the elderly,
and individuals with respiratory disease such as asthma. Those with
greater exposures to ozone, for instance due to time spent outdoors
(e.g., children and outdoor workers), are of particular concern. Ozone
can irritate the respiratory system, causing coughing, throat
irritation, and breathing discomfort. Ozone can reduce lung function
and cause pulmonary inflammation in healthy individuals. Ozone can also
aggravate asthma, leading to more asthma attacks that require medical
attention and/or the use of additional medication. Thus, ambient ozone
may cause both healthy and asthmatic individuals to limit their outdoor
activities. In addition, there is suggestive evidence of a contribution
of ozone to cardiovascular-related morbidity and highly suggestive
evidence that short-term ozone exposure directly or indirectly
contributes to non-accidental and cardiopulmonary-related mortality,
but additional research is needed to clarify the underlying mechanisms
causing these effects. In a report on the estimation of ozone-related
premature mortality published by the National Research Council (NRC), a
panel of experts and reviewers concluded that short-term exposure to
ambient ozone is likely to contribute to premature deaths and that
ozone-related mortality should be included in estimates of the health
benefits of reducing ozone exposure.\36\ Animal toxicological evidence
indicates that with repeated exposure, ozone can inflame and damage the
lining of the lungs, which may lead to permanent changes in lung tissue
and irreversible reductions in lung function. The respiratory effects
observed in controlled human exposure studies and animal studies are
coherent with the evidence from epidemiologic studies supporting a
causal relationship between acute ambient ozone exposures

and increased respiratory-related emergency room visits and
hospitalizations in the warm season. In addition, there is suggestive
evidence of a contribution of ozone to cardiovascular-related morbidity
and non-accidental and cardiopulmonary mortality.
---------------------------------------------------------------------------

    \34\ U.S. EPA. (2006). Air Quality Criteria for Ozone and
Related Photochemical Oxidants (Final). EPA/600/R-05/004aF-cF.
Washington, DC: U.S. EPA.
    \35\ U.S. EPA. (2007). Review of the National Ambient Air
Quality Standards for Ozone: Policy Assessment of Scientific and
Technical Information, OAQPS Staff Paper. EPA-452/R-07-003.
Washington, DC, U.S. EPA.
    \36\ National Research Council. (2008). Estimating Mortality
Risk Reduction and Economic Benefits from Controlling Ozone Air
Pollution. The National Academies Press: Washington, DC.
---------------------------------------------------------------------------

c. Current and Projected Ozone Levels
    Concentrations that exceed the level of the ozone NAAQS occur in
many parts of the country, including many major population centers. In
addition, our modeling without the proposed Tier 3 controls projects
that in the future we will continue to have many areas that will have
ambient ozone concentrations above the level of the NAAQS (see Section
III.C.1). States will need to meet the standard in the 2015-2032
timeframe. The emission reductions and significant ambient ozone
improvements from this proposed rule, which would take effect starting
in 2017, would be helpful to states as they work to attain and maintain
the ozone NAAQS.
    The primary and secondary NAAQS for ozone are 8-hour standards with
a level of 0.075 ppm. The most recent revision to the ozone standards
was in 2008; the previous 8-hour ozone standards, set in 1997, had a
level of 0.08 ppm. In 2004, the U.S. EPA designated nonattainment areas
for the 1997 8-hour ozone NAAQS.37 38 As of December 14,
2012, there were 41 ozone nonattainment areas for the 1997 ozone NAAQS
composed of 221 full or partial counties with a total population of
over 118 million. Nonattainment designations for the 2008 ozone
standard were finalized on April 30, 2012 and May 31, 2012.\39\ These
designations include 46 areas, composed of 227 full or partial
counties, with a population of over 123 million. As of December 14,
2012, over 138 million people are living in ozone nonattainment
areas.\40\
---------------------------------------------------------------------------

    \37\ 69 FR 23858 (April 30, 2004).
    \38\ A nonattainment area is defined in the Clean Air Act (CAA)
as an area that is violating an ambient standard or is contributing
to a nearby area that is violating the standard.
    \39\ 77FR 30088 (May 21, 2012).
    \40\ The 138 million total is calculated by summing, without
double counting, the 1997 and 2008 ozone nonattainment populations
contained in the Summary Nonattainment Area Population Exposure
report (http://www.epa.gov/oar/oaqps/greenbk/popexp.html). If there
is a population associated with both the 1997 and 2008 nonattainment
areas, and they are not the same, then the larger of the two
populations is included in the sum.
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    States with ozone nonattainment areas are required to take action
to bring those areas into attainment. The attainment date assigned to
an ozone nonattainment area is based on the area's classification. Most
ozone nonattainment areas are required to attain the 1997 8-hour ozone
NAAQS in the 2007 to 2013 time frame and then to maintain it
thereafter.\41\ The attainment dates for areas designated nonattainment
for the 2008 8-hour ozone NAAQS are in the 2015 to 2032 timeframe,
depending on the severity of the problem in each area. In addition, EPA
is working to complete the current review of the ozone NAAQS by mid-
2014. If EPA revises the ozone standards in 2014 pursuant to that
review, the attainment dates associated with areas designated
nonattainment for that NAAQS would likely be in the 2019 to 2036
timeframe, depending on the severity of the problem in each area.
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    \41\ The Los Angeles South Coast Air Basin 8-hour ozone
nonattainment area and the San Joaquin Valley Air Basin 8-hour ozone
nonattainment area are designated as extreme and will have to attain
before June 15, 2024. The Sacramento, Coachella Valley, Western
Mojave and Houston 8-hour ozone nonattainment areas are designated
as severe and will have to attain by June 15, 2019.
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    EPA has already adopted many emission control programs that are
expected to reduce ambient ozone levels. As a result of these and other
federal, state and local programs, 8-hour ozone levels are expected to
improve in the future. However, even with the implementation of all
current state and federal regulations, there are projected to be
counties violating the ozone NAAQS well into the future. Thus
additional federal control programs, such as Tier 3, can assist areas
with attainment dates in 2017 and beyond in attaining the NAAQS as
expeditiously as practicable and may relieve areas with already
stringent local regulations from some of the burden associated with
adopting additional local controls.
2. Particulate Matter
a. Background
    Particulate matter is a highly complex mixture of solid particles
and liquid droplets distributed among numerous atmospheric gases which
interact with solid and liquid phases. Particles range in size from
those smaller than 1 nanometer (10-9 meter) to over 100
micrometer ([mu]m, or 10-6 meter) in diameter (for
reference, a typical strand of human hair is 70 [mu]m in diameter and a
grain of salt is about 100 [mu]m). Atmospheric particles can be grouped
into several classes according to their aerodynamic and physical sizes,
including ultrafine particles (<0.1 [mu]m), accumulation mode or `fine'
particles (< 1 to 3 [mu]m), and coarse particles (>1 to 3 [mu]m). For
regulatory purposes, fine particles are measured as PM2.5
and inhalable or thoracic coarse particles are measured as
PM10-2.5, corresponding to their size (diameter) range in
micrometers and referring to total particle mass under 2.5 and between
2.5 and 10 micrometers, respectively. The EPA currently has standards
that measure PM2.5 and PM10.\42\
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    \42\ Regulatory definitions of PM size fractions, and
information on reference and equivalent methods for measuring PM in
ambient air, are provided in 40 CFR parts 50, 53, and 58.
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    Particles span many sizes and shapes and consist of hundreds of
different chemicals. Particles are emitted directly from sources and
are also formed through atmospheric chemical reactions; the former are
often referred to as ``primary'' particles, and the latter as
``secondary'' particles. Particle pollution also varies by time of year
and location and is affected by several weather-related factors, such
as temperature, clouds, humidity, and wind. A further layer of
complexity comes from particles' ability to shift between solid/liquid
and gaseous phases, which is influenced by concentration and
meteorology, especially temperature.
    Fine particles are produced primarily by combustion processes and
by transformations of gaseous emissions (e.g., sulfur oxides
(SOX), nitrogen oxides (NOX), and volatile
organic compounds (VOC)) in the atmosphere. The chemical and physical
properties of PM2.5 may vary greatly with time, region,
meteorology, and source category. Thus, PM2.5 may include a
complex mixture of different components including sulfates, nitrates,
organic compounds, elemental carbon and metal compounds. These
particles can remain in the atmosphere for days to weeks and travel
hundreds to thousands of kilometers.
b. Health Effects of PM
    Scientific studies show ambient PM is associated with a series of
adverse health effects. These health effects are discussed in detail in
EPA's Integrated Science Assessment (ISA) for Particulate Matter.\43\
Further discussion of health effects associated with PM can also be
found in the draft RIA. The ISA summarizes health effects evidence
associated with both short-term and long-term exposures to
PM2.5, PM10-2.5, and ultrafine particles.
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    \43\ U.S. EPA. (2009). Integrated Science Assessment for
Particulate Matter (Final Report). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-08/139F.
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    The ISA concludes that health effects associated with short-term
exposures (hours to days) to ambient PM2.5 include
mortality, cardiovascular effects, such as

altered vasomotor function and myocardial ischemia, and hospital
admissions and emergency department visits for ischemic heart disease
and congestive heart failure, and respiratory effects, such as
exacerbation of asthma symptoms in children and hospital admissions and
emergency department visits for chronic obstructive pulmonary disease
and respiratory infections.\44\ The ISA notes that long-term exposure
(months to years) to PM2.5 is associated with the
development/progression of cardiovascular disease, premature mortality,
and respiratory effects, including reduced lung function growth in
children, increased respiratory symptoms, and asthma development.\45\
The ISA concludes that the currently available scientific evidence from
epidemiologic, controlled human exposure, and toxicological studies
supports a causal association between short- and long-term exposures to
PM2.5 and cardiovascular effects and premature mortality.
Furthermore, the ISA concludes that the collective evidence supports
likely causal associations between short- and long-term
PM2.5 exposures and respiratory effects. The ISA also
concludes that the scientific evidence is suggestive of a causal
association for reproductive and developmental effects including
respiratory-related infant mortality, and cancer, mutagenicity, and
genotoxicity and long-term exposure to PM2.5.\46\
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    \44\ U.S. EPA. (2009). Integrated Science Assessment for
Particulate Matter (Final Report). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-08/139F. Section <IP_ADDRESS>.
    \45\ U.S. EPA. (2009). Integrated Science Assessment for
Particulate Matter (Final Report). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-08/139F. page 2-12, Sections
<IP_ADDRESS> and <IP_ADDRESS>.
    \46\ U.S. EPA. (2009). Integrated Science Assessment for
Particulate Matter (Final Report). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-08/139F. Section 2.3.2.
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    For PM10-2.5, the ISA concludes that the current
evidence is suggestive of a causal relationship between short-term
exposures and premature mortality, cardiovascular effects, and
respiratory effects. Data are inadequate to draw conclusions regarding
the health effects associated with long-term exposure to
PM10-2.5.\47\
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    \47\ U.S. EPA. (2009). Integrated Science Assessment for
Particulate Matter (Final Report). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-08/139F. Section 2.3.4 and Table
2-6.
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    For ultrafine particles, the ISA concludes that there is suggestive
evidence of a causal relationship between short-term exposures and
cardiovascular effects, such as changes in heart rhythm and blood
vessel function. It also concludes that there is suggestive evidence of
association between short-term exposure to ultrafine particles and
respiratory effects. Data are inadequate to draw conclusions regarding
the health effects associated with long-term exposure to ultrafine
particles.\48\
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    \48\ U.S. EPA. (2009). Integrated Science Assessment for
Particulate Matter (Final Report). U.S. Environmental Protection
Agency, Washington, DC, EPA/600/R-08/139F. Section 2.3.5 and Table
2-6.
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c. Current and Projected PM2.5 Levels
    There are many areas of the country that are currently in
nonattainment for the annual and 24-hour PM2.5 NAAQS. Our
modeling without the proposed Tier 3 controls projects that in the
future we will continue to have many areas that will have ambient
PM2.5 concentrations above the level of the NAAQS (see
Section III.C.2). States will need to meet the 24-hour standard in the
2015-2019 timeframe and the annual standard in the 2021-2025 timeframe.
The emission reductions and improvements in ambient PM2.5
from this proposed rule, which would take effect starting in 2017,
would be helpful to states as they work to attain and maintain the
PM2.5 NAAQS.
    There are two NAAQS for PM2.5: an annual standard (12
micrograms per cubic meter ([mu]g/m\3\)) and a 24-hour standard (35
[mu]g/m\3\). The most recent revisions to these standards were in 1997,
2006 and in December 2012. The December 2012 rule revised the level of
the annual PM2.5 standard from 15 [mu]g/m\3\ to 12 [mu]g/
m\3\.\49\
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    \49\ U.S. EPA (2012). National Ambient Air Quality Standards for
Particulate Matter. http://www.epa.gov/PM/2012/finalrule.pdf.
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    In 2005 EPA designated nonattainment areas for the 1997
PM2.5 NAAQS.\50\ As of December 14, 2012, over 91 million
people lived in the 35 areas that are designated as nonattainment for
the 1997 PM2.5 NAAQS. These PM2.5 nonattainment
areas are comprised of 191 full or partial counties. On October 8,
2009, the EPA issued final nonattainment area designations for the 2006
24-hour PM2.5 NAAQS.\51\ These designations include 32 areas
composed of 121 full or partial counties with a population of over 70
million. In total, there are 50 PM2.5 nonattainment areas
with a population of over 105 million people.\52\
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    \50\ 70 FR 19844 (April 14, 2005).
    \51\ 74 FR 58688 (November 13, 2009).
    \52\ Data come from Summary Nonattainment Area Population
Exposure Report, current as of December 14, 2012 at: http://www.epa.gov/oar/oaqps/greenbk/popexp.html and contained in Docket
EPA-HQ-OAR-2011-0135.
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    States with PM2.5 nonattainment areas will be required
to take action to bring those areas into attainment in the future. Most
1997 PM2.5 nonattainment areas are required to attain the
1997 PM2.5 NAAQS in the 2010 to 2015 time frame and then
required to maintain the 1997 PM2.5 NAAQS thereafter.\53\
The 2006 24-hour PM2.5 nonattainment areas will be required
to attain the 2006 24-hour PM2.5 NAAQS in the 2014 to 2019
time frame and then be required to maintain the 2006 24-hour
PM2.5 NAAQS thereafter.\54\ The 2012 PM2.5
nonattainment areas will likely be required to attain the 2012
PM2.5 NAAQS in the 2020 to 2025 time frame, depending on the
severity of an area's fine particle pollution problems and the
availability of pollution controls. The standards proposed here begin
taking effect in 2017.
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    \53\ U.S. EPA. (2007). PM2.5 National Ambient Air
Quality Standard Implementation Rule (Final). Washington, DC: U.S.
EPA. 72 FR 20586, April 25, 2007.
    \54\ U.S. EPA. (2011). PM Standards Revision--2006: Timeline.
Available at http://www.epa.gov/PM/naaqsrev2006.html#timeline.
Accessed December 31, 2011.
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    EPA has already adopted many mobile source emission control
programs that are expected to reduce ambient PM levels. As a result of
these and other federal, state and local programs, the number of areas
that fail to meet the PM2.5 NAAQS in the future is expected
to decrease. However, even with the implementation of all current state
and federal regulations, there are projected to be counties violating
the PM2.5 NAAQS well into the future. Thus additional
federal control programs, such as Tier 3, can assist areas with
attainment dates in 2017 and beyond in attaining the NAAQS as
expeditiously as practicable and may relieve areas with already
stringent local regulations from some of the burden associated with
adopting additional local controls.
3. Nitrogen Oxides and Sulfur Oxides
a. Background
    Nitrogen dioxide (NO2) is a member of the NOX
family of gases. Most NO2 is formed in the air through the
oxidation of nitric oxide (NO) emitted when fuel is burned at a high
temperature. Sulfur dioxide (SO2), a member of the sulfur
oxide (SOX) family of gases, is formed from burning fuels
containing sulfur (e.g., coal or oil derived), extracting gasoline from
oil, or extracting metals from ore.
    SO2 and NO2 and their gas phase oxidation
products can dissolve in water droplets and further oxidize to form
sulfuric and nitric acid which react with ammonia to form sulfates and

nitrates, both of which are important components of ambient PM. The
health effects of ambient PM are discussed in Section II.B.2.b of this
preamble. NOX and VOC are the two major precursors of ozone.
The health effects of ozone are covered in Section II.B.2.1.b.
b. Health Effects of NO2
    Information on the health effects of NO2 can be found in
the EPA Integrated Science Assessment (ISA) for Nitrogen Oxides.\55\
The EPA has concluded that the findings of epidemiologic, controlled
human exposure, and animal toxicological studies provide evidence that
is sufficient to infer a likely causal relationship between respiratory
effects and short-term NO2 exposure. The ISA concludes that
the strongest evidence for such a relationship comes from epidemiologic
studies of respiratory effects including symptoms, emergency department
visits, and hospital admissions. Based on both short- and long-term
studies, the ISA concludes that associations of NO2 with
respiratory health effects are stronger among a number of groups; these
include individuals with preexisting pulmonary conditions (e.g., asthma
or COPD), children and older adults. The ISA also draws two broad
conclusions regarding airway responsiveness following NO2
exposure. First, the ISA concludes that NO2 exposure may
enhance the sensitivity to allergen-induced decrements in lung function
and increase the allergen-induced airway inflammatory response
following 30-minute exposures of asthmatics to NO2
concentrations as low as 0.26 ppm. Second, exposure to NO2
has been found to enhance the inherent responsiveness of the airway to
subsequent nonspecific challenges in controlled human exposure studies
of asthmatic subjects. Small but significant increases in non-specific
airway hyperresponsiveness were reported following 1-hour exposures of
asthmatics to 0.1 ppm NO2. Enhanced airway responsiveness
could have important clinical implications for asthmatics since
transient increases in airway responsiveness following NO2
exposure have the potential to increase symptoms and worsen asthma
control. Together, the epidemiologic and experimental data sets form a
plausible, consistent, and coherent description of a relationship
between NO2 exposures and an array of adverse health effects
that range from the onset of respiratory symptoms to hospital
admission.
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    \55\ U.S. EPA (2008). Integrated Science Assessment for Oxides
of Nitrogen--Health Criteria (Final Report). EPA/600/R-08/071.
Washington, DC: U.S.EPA.
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    Although the weight of evidence supporting a causal relationship is
somewhat less certain than that associated with respiratory morbidity,
NO2 has also been linked to other health endpoints. These
include all-cause (nonaccidental) mortality, hospital admissions or
emergency department visits for cardiovascular disease, and decrements
in lung function growth associated with chronic exposure.
c. Health Effects of SO2
    Information on the health effects of SO2 can be found in
the EPA Integrated Science Assessment for Sulfur Oxides.\56\
SO2 has long been known to cause adverse respiratory health
effects, particularly among individuals with asthma. Other potentially
sensitive groups include children and the elderly. During periods of
elevated ventilation, asthmatics may experience symptomatic
bronchoconstriction within minutes of exposure. Following an extensive
evaluation of health evidence from epidemiologic and laboratory
studies, the EPA has concluded that there is a causal relationship
between respiratory health effects and short-term exposure to
SO2. Separately, based on an evaluation of the epidemiologic
evidence of associations between short-term exposure to SO2
and mortality, the EPA has concluded that the overall evidence is
suggestive of a causal relationship between short-term exposure to