[Federal Register Volume 71, Number 47 (Friday, March 10, 2006)]
[Rules and Regulations]
[Pages 12468-12511]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-2178]



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Part III





Environmental Protection Agency





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40 CFR Part 93



PM2.5 and PM10 Hot-Spot Analyses in Project-Level 
Transportation Conformity Determinations for the New PM2.5 
and Existing PM10 National Ambient Air Quality Standards; 
Final Rule

  Federal Register / Vol. 71, No. 47 / Friday, March 10, 2006 / Rules 
and Regulations  

[[Page 12468]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 93

[EPA-HQ-OAR-2003-0049, FRL-8039-5]
RIN 2060-AN02


PM2.5 and PM10 Hot-Spot Analyses in 
Project-Level Transportation Conformity Determinations for the New 
PM2.5 and Existing PM10 National Ambient Air Quality Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This final rule establishes the criteria for determining which 
transportation projects must be analyzed for local particle emissions 
impacts in PM2.5 and PM10 nonattainment and maintenance areas. This 
rule establishes requirements in PM2.5 areas and revises 
existing requirements in PM10 areas. If required, an 
analysis of local particle emissions impacts is done as part of a 
transportation project's conformity determination. EPA is requiring a 
local particle emissions impacts analysis for certain transportation 
projects to ensure that these projects do not adversely impact the 
national ambient air quality standards and human health. The Clean Air 
Act requires federally supported highway and transit projects to be 
consistent with (``conform to'') the purpose of a state air quality 
implementation plan. EPA has consulted with the Department of 
Transportation (DOT) on the development of this final rule, and DOT 
concurs with its content.

DATES: The final rule is effective April 5, 2006, for good cause found 
as explained in this rule.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-HQ-OAR-2003-0049. All documents in the docket are listed on the 
http://www.regulations.gov Web site. Although listed in the index, some 
information may not be publicly available, e.g., Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute. Certain other material, such as copyrighted material, is 
not placed on the Internet and will be publicly available only in hard 
copy form. Publicly available docket materials are available either 
electronically through http://www.regulations.gov or in hard copy at 
the Air Docket, EPA/DC, EPA West, Room B102, 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 (202) 566-1744, and the 
telephone number for the Air Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Meg Patulski, Transportation and 
Regional Programs Division, Office of Transportation and Air Quality, 
U.S. Environmental Protection Agency, 2000 Traverwood Road, Ann Arbor, 
MI 48105, telephone number: (734) 214-4842, fax number: (734) 214-4052, 
e-mail address: [email protected]; or Rudy Kapichak, Transportation 
and Regional Programs Division, Office of Transportation and Air 
Quality, U.S. Environmental Protection Agency, 2000 Traverwood Road, 
Ann Arbor, MI 48105, telephone number: (734) 214-4574, fax number: 
(734) 214-4052, e-mail address: [email protected].

SUPPLEMENTARY INFORMATION:
    The contents of this preamble are listed in the following outline:

I. General Information
II. Background
III. PM2.5 Hot-spot Analyses
IV. PM10 Hot-spot Analyses
V. Projects of Air Quality Concern and General Requirements for 
PM2.5 and PM10 Hot-spot Analyses
VI. Timing of Quantitative PM2.5 and PM10 Hot-
spot Analyses and Development of Future Guidance
VII. Categorical PM2.5 and PM10 Hot-spot 
Findings
VIII. Minor Change for Exempt Projects Regarding Compliance With 
PM2.5 SIP Control Measures
IX. How Does Today's Final Rule Affect Conformity SIPs?
X. Statutory and Executive Order Reviews

I. General Information

A. Does This Action Apply to Me?

    Entities potentially regulated by the transportation conformity 
rule are those that adopt, approve, or fund transportation plans, 
programs, or projects under title 23 U.S.C. or title 49 U.S.C. 
Regulated categories and entities affected by today's action include:

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                                                Examples of regulated
                 Category                             entities
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Local government..........................  Local transportation and air
                                             quality agencies, including
                                             metropolitan planning
                                             organizations (MPOs).
State government..........................  State transportation and air
                                             quality agencies.
Federal government........................  Department of Transportation
                                             (Federal Highway
                                             Administration (FHWA) and
                                             Federal Transit
                                             Administration (FTA)).
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    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by this 
final rule. This table lists the types of entities of which EPA is 
aware that potentially could be regulated by the conformity rule. Other 
types of entities not listed in the table could also be regulated. To 
determine whether your organization is regulated by this action, you 
should carefully examine the applicability requirements in 40 CFR 
93.102. If you have questions regarding the applicability of this 
action to a particular entity, consult the persons listed in the 
preceding FOR FURTHER INFORMATION CONTACT section.

B. How Can I Get Copies of This Document?

1. Docket
    EPA has established an official public docket for this action under 
Docket ID No. EPA-HQ-OAR-2003-0049. The official public docket consists 
of the documents specifically referenced in this action, any public 
comments received, and other information related to this action. 
Although a part of the official docket, the public docket does not 
include Confidential Business Information (CBI) or other information 
whose disclosure is restricted by statute. The official public docket 
is the collection of materials that is available for public viewing at 
the Air Docket in the EPA Docket Center. See the ADDRESSES section 
above. You may have to pay a reasonable fee for copying docket 
materials.
2. Electronic Access
    You may access this Federal Register document electronically 
through EPA's transportation conformity Web site at http://www.epa.gov/otag/transp/tragconf.htm. You may also access this document 
electronically under the ``Federal Register'' listings at http://www.epa.gov/fedrgstr/.
    An electronic version of the public docket is available through the 
Federal Docket Management System (FDMS), located at http://www.regulations.gov. You may use the FDMS to view public comments, 
access the index listing of the contents of the official public docket, 
and to access those documents in the public docket that are available

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electronically. Although not all docket materials may be available 
electronically, you may still access any of the publicly available 
docket materials through the docket facility identified in B.1. of this 
section. Once in the FDMS electronic docket system, select ``Advanced 
Search-Docket Search,'' then enter the appropriate docket 
identification number (which is EPA-HQ-OAR-2003-0049) in the ``docket 
ID'' field and click ``submit''.

II. Background

A. What Is Transportation Conformity?

    Transportation conformity is required under Clean Air Act section 
176(c) (42 U.S.C. 7506(c)) to ensure that federally supported highway 
and transit project activities are consistent with (``conform to'') the 
purpose of the state air quality implementation plan (SIP). Conformity 
currently applies to areas that are designated nonattainment, and those 
redesignated to attainment after 1990 (``maintenance areas'' with plans 
developed under Clean Air Act section 175A) for the following 
transportation-related criteria pollutants: Ozone, particulate matter 
(PM2.5 and PM10),\1\ carbon monoxide (CO), and 
nitrogen dioxide (NO2). Conformity to the purpose of the SIP 
means that transportation activities will not cause new air quality 
violations, worsen existing violations, or delay timely attainment of 
the relevant national ambient air quality standards (NAAQS or 
``standards'').
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    \1\ Section 93.102(b)(1) of the conformity rule defines 
PM2.5 and PM10 as particles with an 
aerodynamic diameter less than or equal to a nominal 2.5 and 10 
micrometers, respectively.
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B. What Is the History of the Transportation Conformity Rule?

    EPA's transportation conformity rule establishes the criteria and 
procedures for determining whether transportation activities conform to 
the SIP. EPA first promulgated the transportation conformity rule on 
November 24, 1993 (58 FR 62188), and subsequently published a 
comprehensive set of amendments on August 15, 1997 (62 FR 43780) that 
clarified and streamlined language from the 1993 rule. EPA has made 
other smaller amendments to the rule both before and after the 1997 
amendments.
    More recently, on July 1, 2004, EPA published a final rule (69 FR 
40004) that amended the conformity rule to accomplish three objectives. 
The final rule:
     Provided conformity procedures for state and local 
agencies under the new ozone and PM2.5 air quality 
standards;
     Incorporated existing EPA and DOT federal guidance into 
the conformity rule consistent with a March 2, 1999 U.S. Court of 
Appeals decision; and
     Streamlined and improved the conformity rule.

The July 1, 2004 final rule incorporated most of the provisions from 
the November 5, 2003 proposal for conformity under the new ozone and 
PM2.5 standards (68 FR 62690). EPA is conducting its 
conformity rulemakings in the context of EPA's broader strategies for 
implementing the new ozone and PM2.5 standards.
    Finally, on May 6, 2005, EPA promulgated a final rule entitled, 
``Transportation Conformity Rule Amendments for the New 
PM2.5 National Ambient Air Quality Standard: 
PM2.5 Precursors'' (70 FR 24280). This final rule specified 
the transportation-related PM2.5 precursors and when they 
apply in transportation conformity determinations in PM2.5 
nonattainment and maintenance areas.

C. Why Are We Issuing This Final Rule?

    In the November 2003 proposal, EPA presented two options concerning 
hot-spot analyses in PM2.5 and PM10 nonattainment 
and maintenance areas. EPA received substantial comment on this portion 
of the November 2003 proposal. After considering these comments, EPA, 
in consultation with the U.S. Department of Transportation (DOT), 
issued a supplemental notice of proposed rulemaking on December 13, 
2004 (69 FR 72140) which requested further public comment on additional 
options for PM2.5 and PM10 hot-spot requirements 
and those options presented in the original November 2003 proposal. In 
developing today's final rule, EPA considered all of the comments 
received on PM2.5 and PM10 hot-spot analysis 
requirements both in response to the original November 2003 proposal as 
well as the December 2004 supplemental proposal. EPA received over 
5,400 sets of comments on the two proposals from state and local 
transportation and air quality agencies, environmental groups, 
transportation advocates, and the general public.
    EPA has consulted with DOT, our Federal partner in implementing the 
transportation conformity regulation, in developing the final rule, and 
DOT concurs with its content. Please see Sections III. and IV. for more 
information regarding how this final rule impacts project-level 
conformity determinations in PM2.5 and PM10 
areas, including those for projects that are currently under 
development.

III. PM2.5 Hot-spot Analyses

A. Background

1. What Is a Hot-spot Analysis?
    A hot-spot analysis is defined in 40 CFR 93.101 as an estimation of 
likely future localized pollutant concentrations resulting from a new 
transportation project and a comparison of those concentrations to the 
relevant air quality standard. A hot-spot analysis assesses the air 
quality impacts on a scale smaller than an entire nonattainment or 
maintenance area, including, for example, congested roadway 
intersections and highways or transit terminals. Such an analysis is a 
means of demonstrating that a transportation project meets Clean Air 
Act conformity requirements to support state and local air quality 
goals with respect to potential localized air quality impacts.
    Prior to today's final rule, the conformity rule required some type 
of hot-spot analysis for all FHWA and FTA funded or approved non-exempt 
transportation projects in CO and PM10 nonattainment and 
maintenance areas (40 CFR 93.116 and 93.123). This requirement applied 
for all project-level conformity determinations that occur both before 
and after a SIP is submitted for the CO or PM10 air quality 
standards.
    EPA established the type of hot-spot analysis--either quantitative 
or qualitative--based on the potential impact of a given project or 
project location on the air quality standards, so that more rigorous 
quantitative analyses are only required when necessary to meet 
statutory requirements. Since the original November 24, 1993 conformity 
rule, EPA has required quantitative analyses for projects that have the 
highest potential to impact the CO air quality standards (i.e., 
``projects of air quality concern''). The conformity rule also has 
detailed projects that have the highest potential to impact the 
PM10 standards, including new or expanded bus and rail 
terminals or transfer points involving diesel vehicles. These projects 
of air quality concern would be subject to quantitative hot-spot 
analyses once the tools and EPA's future modeling guidance are 
available. In contrast, more streamlined, qualitative hot-spot analyses 
have been required for all other projects.
    Such a tiered approach was intended to utilize state and local 
resources in an efficient manner while meeting statutory requirements. 
Quantitative hot-spot analyses use dispersion modeling to determine the 
potential air quality impact of motor vehicle emissions associated with 
a highway or

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transit project. Qualitative hot-spot analyses involve more streamlined 
reviews of local factors such as local monitoring data near a proposed 
project.
    EPA notes, however, that quantitative PM10 hot-spot 
analyses have not yet been required for projects of air quality concern 
due to a lack of EPA modeling guidance and appropriate methods. Section 
93.123(b)(4) of the conformity rule states that the requirements for 
quantitative PM10 hot-spot analyses will not take effect 
until EPA releases modeling guidance and announces in the Federal 
Register that these requirements are in effect, which EPA has not yet 
done.
    Today's final rule does not impact the existing CO hot-spot 
requirements; however, the final rule revises the PM10 hot-
spot requirements as discussed in Sections IV. and V.
2. Proposed Options
    EPA proposed several options for how PM2.5 hot-spot 
requirements would apply for project-level conformity determinations in 
PM2.5 nonattainment and maintenance areas. In general, these 
options were proposed to apply during the time periods before and after 
a PM2.5 SIP is submitted. EPA is repeating in today's action 
the descriptions of the previously proposed options to assist in 
discussing the final rule and responses to comments. EPA noted in its 
proposals that hot-spot analyses would be based only on directly 
emitted PM2.5 attributable to an individual transportation 
project, since secondary particles formed through PM2.5 
precursors take several hours to form in the atmosphere, giving 
emissions time to disperse beyond the immediate area of concern for 
localized analyses.
    The following five options were proposed for PM2.5 hot-
spot requirements for individual projects in PM2.5 areas 
prior to the submission of a PM2.5 SIP (December 13, 2004, 
69 FR 72144):
     Options 1 and 2: Do not apply any PM2.5 hot-
spot analysis requirements for any PM2.5 area before the 
submission of the PM2.5 SIP \2\;
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    \2\ Options 1 and 2 were originally proposed in the November 5, 
2003 notice as well (68 FR 62712). Option 1 would have not required 
any PM2.5 hot-spot requirement at any time before or 
after a PM2.5 SIP is submitted. Option 2 also would not 
require PM2.5 hot-spot analyses prior to a 
PM2.5 SIP submission, and then only if the SIP identified 
types of projects or locations of air quality concern for a given 
area.
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     Option 3: Apply the existing conformity rule's 
PM10 hot-spot analysis requirements with respect to 
PM2.5 in all PM2.5 areas;
     Option 4: Apply the existing conformity rule's 
PM10 hot-spot analysis requirements with respect to 
PM2.5, unless the EPA Regional Administrator or state air 
agency finds that localized PM2.5 violations are not a 
concern for a given PM2.5 area; or
     Option 5: Apply the existing conformity rule's 
PM10 hot-spot analysis requirements with respect to 
PM2.5, only if the EPA Regional Administrator or state air 
agency finds that localized PM2.5 violations are a concern 
for a given PM2.5 area.
    EPA proposed that an EPA or state air agency finding under Options 
4 and 5 that PM2.5 localized violations are or are not a 
concern prior to PM2.5 SIP submission would be based on a 
case-by-case review of local factors for a given PM2.5 area. 
EPA requested information from commenters about whether sufficient 
local information was available to make such findings.
    EPA also proposed three options for project-level conformity 
determinations after the submission of a PM2.5 SIP (December 
13, 2004, 69 FR 72145):
     Option A: Do not apply any PM2.5 hot-spot 
analysis requirements for any PM2.5 area (i.e., Option 1 
from the November 2003 proposal);
     Option B: Only require quantitative PM2.5 hot-
spot analyses for projects at those types of locations that the 
PM2.5 SIP identifies as a localized PM2.5 air 
quality concern for a given area (i.e., Option 2 from the November 2003 
proposal). No quantitative or qualitative analyses would be required 
for any projects in other types of locations, or in PM2.5 
areas where the SIP does not identify types of locations as a localized 
PM2.5 air quality concern; or
     Option C: Apply the existing conformity rule's 
PM10 hot-spot analysis requirements with respect to 
PM2.5 for all projects in PM2.5 areas, with a 
minor addition.
    Under Option C, EPA proposed to add a new criterion that would 
require that quantitative analyses also be performed at those types of 
project locations that the PM2.5 SIP identifies as a 
PM2.5 hot-spot concern. See the November 5, 2003 proposal 
(68 FR 62712-62713) and the December 13, 2004 supplemental proposal (69 
FR 72144-72149) for further information on all of the proposed options.
    For options involving hot-spot analyses, EPA proposed to not 
require quantitative PM2.5 hot-spot analyses until EPA 
releases its future modeling guidance, consistent with the existing 
provision for PM10 analyses in Sec.  93.123(b)(4). EPA also 
proposed to extend to PM2.5 areas the existing conformity 
rule's flexibility in Sec.  93.123(b)(3) for DOT to make categorical 
hot-spot findings to further streamline analysis requirements when 
modeling shows that additional analyses are not necessary to meet Clean 
Air Act requirements for a given project.
    Last, EPA requested comments on all of the proposed options, and 
invited commenters to submit any data or other information about the 
proposed options, including whether state and local agencies would have 
information available for implementation. In developing this final 
rule, EPA considered all of the comments and information submitted for 
the November 2003 and December 2004 proposals. The December 2004 
supplemental proposal also included proposed regulatory text that 
combined various PM2.5 and PM10 hot-spot options 
as illustrative examples, and EPA noted that any combination of the 
proposed PM2.5 or PM10 hot-spot options could be 
included in the final rule.

B. Description of Final Rule

    In summary, EPA is finalizing a hybrid of some of the proposed 
options by:
    Being generally consistent with Options 3 (for the period before a 
SIP is submitted) and C (for the period after a SIP is submitted) for 
projects of localized air quality concern, and
     Providing the flexibility from other proposed options to 
eliminate qualitative hot-spot analyses for all projects not of air 
quality concern.

The final rule requires quantitative PM2.5 hot-spot analyses 
only for projects of air quality concern, and qualitative hot-spot 
analyses would be done for these projects before EPA releases its 
future modeling guidance and announces that quantitative 
PM2.5 hot-spot analyses are required under Sec.  
93.123(b)(4). EPA specifies in Sec.  93.123(b)(1) that projects of air 
quality concern are highway and transit projects that involve 
significant levels of diesel vehicle traffic, or any other project that 
is identified in the PM2.5 SIP as a localized concern.
    EPA considered several factors in focusing on projects involving 
significant numbers of diesel vehicles in developing today's final 
rule. For example, PM2.5 and PM10 diesel emission 
factors are significantly higher than gasoline vehicles on a per-
vehicle basis. In addition, studies in proximity of vehicular traffic 
tend to show that elevated PM2.5 concentrations occur near 
diesel vehicle operations, but show less consistent evidence near 
locations with high gasoline vehicle operations. See Section V. for 
more information regarding how and why EPA defined projects of air 
quality concern in the final rule.

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    Today's final rule does not require any hot-spot analysis--
qualitative or quantitative--for projects that are not listed in Sec.  
93.123(b)(1) as an air quality concern. These projects are presumed to 
meet Clean Air Act requirements and 40 CFR 93.116 without any explicit 
hot-spot analysis for the reasons explained in full below. State and 
local project sponsors should briefly document in their conformity 
documentation for such projects that an explicit PM2.5 hot-
spot analysis was not completed because Clean Air Act and 40 CFR 93.116 
requirements were met without an explicit PM2.5 hot-spot 
analysis.
    This final rule requires PM2.5 hot-spot analyses for 
projects of air quality concern in PM2.5 nonattainment and 
maintenance areas at all times--both before and after a 
PM2.5 SIP is submitted. EPA had distinguished its proposed 
options for the time periods before and after PM2.5 SIPs are 
submitted, but for reasons discussed further below, this type of 
specificity is no longer necessary. Projects of air quality concern are 
anticipated to have the potential to increase local PM2.5 
concentrations, and as a result, PM2.5 hot-spot analyses are 
needed for such projects to ensure that the local air quality impacts 
of such projects are considered prior to receiving federal funding or 
approval. EPA is finalizing specific criteria about the types of 
projects that require such analyses, based on our November 2003 and 
December 2004 proposals and comments received. See Section V. of this 
notice for further details regarding the regulatory criteria for 
projects of air quality concern and more information on the general 
requirements for performing hot-spot analyses.
    In addition, the final rule allows DOT, in consultation with EPA, 
to make categorical hot-spot findings that would further streamline 
quantitative hot-spot analysis requirements in appropriate cases in 
PM2.5 areas, as the existing conformity rule already allows 
in PM10 areas for some projects. A categorical hot-spot 
finding would be made if there is appropriate modeling that shows that 
a particular category of highway or transit projects of air quality 
concern meet statutory requirements without additional quantitative 
hot-spot modeling for such types of projects individually. See Section 
VII. for further details regarding categorical hot-spot findings.
    This final rule requires a qualitative PM2.5 hot-spot 
analysis to be completed for project-level conformity determinations 
for projects of air quality concern completed in PM2.5 
nonattainment areas on or after April 5, 2006, when PM2.5 
conformity requirements apply.\3\ Quantitative analyses are not 
required for these projects at this time since EPA is not requiring 
quantitative PM2.5 hot-spot analyses under Sec.  
93.123(b)(4) since quantitative hot-spot modeling techniques and 
associated EPA modeling guidance still do not exist. Qualitative 
PM2.5 hot-spot analyses should be completed according to 
joint EPA and DOT guidance. This guidance was developed in consultation 
with DOT, and the guidance will be posted on the Web site provided in 
Section I.B.2. of today's notice. See Section VI. of this final rule 
for more information regarding the timing of EPA's future quantitative 
hot-spot modeling guidance and subsequent application of quantitative 
requirements.
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    \3\ On January 5, 2005 (70 FR 943), EPA designated areas as 
attainment and nonattainment for the PM2.5 standards. 
These designations became effective on April 5, 2005. As a result, 
conformity for the PM2.5 standards will apply to newly 
designated nonattainment areas on April 5, 2006.
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    Finally, EPA notes that its future quantitative hot-spot modeling 
guidance will also address how the current 24-hour and annual 
PM2.5 air quality standards are to be considered in 
quantitative hot-spot analyses. The Clean Air Act and conformity rule 
require that conformity be met for both the 24-hour and annual 
PM2.5 air quality standards in all PM2.5 
nonattainment and maintenance areas. However, transportation plan and 
transportation improvement program (TIP) conformity determinations and 
regional emissions analyses could address only one PM2.5 
standard if meeting conformity for the controlling standard would 
ensure that Clean Air Act requirements are met for both standards. EPA 
will address how PM2.5 hot-spot analyses should consider 
both applicable PM2.5 standards in our future quantitative 
hot-spot modeling guidance. This future guidance will be consistent 
with how potential impacts on the PM2.5 standards are being 
considered in EPA's rulemaking for the PM2.5 implementation 
strategy, which EPA proposed on November 1, 2005 (70 FR 66040). 
Quantitative hot-spot analyses for conformity purposes would consider 
how projects of air quality concern are predicted to impact air quality 
at existing and potential PM2.5 monitor locations which are 
appropriate to allow the comparison of predicted PM2.5 
concentrations to the current PM2.5 standards, based on 
PM2.5 monitor siting requirements (40 CFR part 58). EPA 
developed these monitor siting requirements to determine the level of 
protection of community public health provided by the current 
PM2.5 standards.

C. Rationale

    In its December 2004 supplemental proposal, EPA stated that several 
factors needed to be considered for establishing a PM2.5 
hot-spot requirement. Those factors are as follows:
     The Clean Air Act conformity requirements for individual 
transportation projects;
     The current scientific understanding of PM2.5 
hot-spots and public health effects;
     The feasibility of implementing a PM2.5 hot-
spot requirement; and
     The impact on state and local resources.
    The following paragraphs outline how EPA considered these factors 
in the final rule.
    Clean Air Act legal requirements: EPA believes that the final rule 
allows all federally funded and approved transportation projects in 
PM2.5 areas to meet applicable statutory requirements. Clean 
Air Act section 176(c)(1)(B) is the statutory criterion that must be 
met by all projects in nonattainment and maintenance areas that are 
subject to transportation conformity. Section 176(c)(1)(B) states that 
federally-supported transportation projects must not ``cause or 
contribute to any new violation of any standard in any area; increase 
the frequency or severity of any existing violation of any standard in 
any area; or delay timely attainment of any standard or any required 
interim emission reductions or other milestones in any area.'' The 
Clean Air Act requires that these provisions be met for all FHWA or FTA 
funded or approved projects, except traffic signal synchronization 
projects; it does not distinguish that these requirements apply based 
on whether or not a SIP has been submitted. Through previous 
rulemaking, EPA has determined that the exempt projects listed in 40 
CFR 93.126 have met section 176(c)(1)(B) without further hot-spot 
analyses. Through today's action, EPA is determining that projects not 
identified in the rule as projects of air quality concern have also met 
section 176(c)(1)(B) without further hot-spot analyses. The final rule 
requires that all projects of air quality concern be analyzed for 
localized impacts, regardless of whether or not the PM2.5 
SIP is submitted.
    EPA continues to believe it has discretion to establish the level 
and form of PM2.5 analysis that is necessary to meet Clean 
Air Act section 176(c) statutory requirements. Therefore, EPA is 
finalizing criteria for when PM2.5 hot-spot analyses are 
required based on scientific information available on PM2.5

[[Page 12472]]

hot-spots and emissions from diesel vehicles, and the Agency's 
experience in implementing CO and PM10 hot-spot requirements 
since 1993 for what level of analysis is appropriate and worthwhile. 
The final rule's criteria for what projects require hot-spot analyses 
will ensure that all projects that have the potential to impact the air 
quality standards will be analyzed using appropriate methods before 
they receive Federal funding or approval. The final rule includes 
criteria for what projects of air quality concern require quantitative 
PM2.5 analyses based on existing scientific information and 
comments received, as discussed further in this section and in Section 
V.
    Furthermore, EPA is changing its precedent to date in no longer 
requiring qualitative hot-spot analyses for projects that are not of 
localized air quality concern. As stated previously, since the original 
1993 conformity rule, some type of hot-spot analysis has been required 
to meet statutory requirements for all non-exempt FHWA and FTA projects 
in PM10 nonattainment and maintenance areas. However, based 
on the history of implementation of this provision over the past ten 
plus years, as explained in more detail below, EPA now believes that 
these projects which do not represent a localized air quality concern 
can be presumed to meet Clean Air Act requirements and 40 CFR 93.116 
without any explicit hot-spot analysis.
    Requiring qualitative hot-spot analyses for projects that are not 
an air quality concern is also not a beneficial use of Federal, state, 
or local resources. EPA is basing this conclusion in part on a recent 
review by EPA and DOT field offices of project-level conformity 
determinations involving historical qualitative hot-spot analyses in 
PM10 areas. This review did not find any qualitative hot-
spot analysis in a PM10 nonattainment or maintenance area 
where it was determined that Clean Air Act requirements were not met. 
In other words, qualitative hot-spot analyses for projects that are not 
an air quality concern in PM10 areas did not result in any 
predicted new or worsened air quality violations.
    In addition, EPA and DOT offices evaluated whether any mitigation 
measures had been added to a project in response to a PM10 
qualitative hot-spot analyses. Mitigation measures are sometimes used 
to reduce project emissions and any impact on local air quality, so 
that a project can demonstrate conformity. Whatever the case, the EPA 
and DOT field offices did not identify any cases where any mitigation 
measures were added to reduce emissions from implemented projects to 
meet statutory conformity requirements. EPA found in its review of 
previous qualitative PM10 hot-spot analyses that mitigation 
measures were added in some cases to reduce fugitive dust emissions 
during project construction (e.g., slope covering, street sweeping, use 
of water, quarry spalls). However, these measures were added for other 
mitigation purposes during the construction phase of a project, rather 
than to meet conformity requirements for the time period when 
construction is completed and a project is open to traffic. EPA has 
included a summary of its review in the docket for this rulemaking.
    For all of these reasons and since EPA does not expect these 
projects to ever impact the PM2.5 standards, EPA has not 
finalized any hot-spot analysis requirement for projects that are not 
an air quality concern. EPA concludes that since no such projects will 
have localized air quality impacts of concern, all such projects can 
meet statutory conformity requirements without an explicit hot-spot 
analysis.
    However, as noted elsewhere in today's action, EPA is finalizing a 
qualitative PM2.5 hot-spot requirement for projects of air 
quality concern prior to quantitative guidance and models being 
available. EPA believes that there is value in federal, state, and 
local agencies and the general public discussing the localized air 
quality impacts of a project of air quality concern, even if such 
reviews can only be qualitative in nature at this time. This aspect of 
the final rule is intended to be an environmentally conservative 
approach to meeting Clean Air Act requirements in the time period 
before quantitative hot-spot modeling techniques and future guidance is 
available for projects of localized air quality concern.
    Scientific understanding of potential for transportation-related 
PM2.5 hot-spots: Another critical factor for developing the 
final rule is whether or not transportation projects have the potential 
to affect the PM2.5 standards in local areas. Understanding 
whether or not an individual transportation project can result in a 
PM2.5 hot-spot and if so, under what circumstances, provides 
a basis for considering whether explicit hot-spot analyses must be 
required for conformity purposes, and if so for which types of projects 
or potential project locations.
    As discussed above, EPA believes that highway and transit projects 
that involve significant levels of diesel vehicle emissions have the 
potential to increase local PM2.5 concentrations. As a 
result, PM2.5 hot-spot analyses are needed to ensure that 
the local air quality impacts of such projects are considered prior to 
receiving Federal funding or approval. This finding is based on EPA's 
thorough review of existing scientific papers as well as additional 
technical and anecdotal information that was submitted by state and 
local agencies during the rulemaking process. All of this information 
is contained in the docket for this rulemaking.
    In developing the final rule, EPA completed a thorough review of 
more than 70 studies representing a cross-section of available studies 
looking at particle concentrations near roadways. Some of these studies 
were considered for our previous proposals; others were newly 
considered for the final rule. Some of these studies are discussed in 
today's action; all studies are included in the docket for this final 
rule.
    EPA believes that these studies provide strong evidence of elevated 
PM2.5 concentrations along roadways on a consistent basis 
from certain types of projects. Based on EPA's review of all studies, 
studies identified elevated PM2.5 concentrations of 8% to 
60% for high-traffic roadways to 285% for major truck stops, compared 
to background concentrations. Variables identified in the studies as 
key predictors of PM2.5 concentrations include: Total 
traffic volume; volume of heavy-duty trucks; traffic congestion; and 
proximity to major facilities (within approximately 150 meters). Most 
studies showed elevation in PM2.5, black carbon, or other 
components \4\ associated with major facilities (e.g., truck routes, 
intermodal or bus terminals). Several showed no elevation in 
PM2.5 per se, but did show elevation in black carbon, 
particle number, or some other component of PM2.5. Only one 
study showed no elevation in any component of PM2.5 close to 
roadways.
---------------------------------------------------------------------------

    \4\ Examples of other components that are considered 
PM2.5 include organic carbon and particle-phase 
polycyclic aromatic hydrocarbons.
---------------------------------------------------------------------------

    Overall, major conclusions from these studies are:
     Black/elemental carbon (BC or EC) mass concentrations and 
particle number (e.g., ``ultrafines'') concentrations are consistently 
associated with proximity to traffic (generally within 150 meters).
     PM2.5 is associated with proximity to traffic 
in most, but not all cases.
     Both regional background and local sources contribute to 
site-specific PM2.5 concentrations.
     The ``near-roadway increment'' of PM2.5 tends 
to be comprised of approximately 50-80% black or

[[Page 12473]]

elemental carbon (indicating mobile sources are a key source).
    Some examples of the types of studies we examined include Lena et 
al. (2002), where investigators from Columbia University conducted a 
community-based study in a neighborhood of the South Bronx, NY, with 
heavy freight traffic. Vehicle counts and EC concentrations were 
monitored over a 10-12 hour period at several sites along designated 
truck routes and other neighborhood sites. Within the neighborhood, EC 
was 20-28% of ambient PM2.5 along truck routes, but only 13-
16% at non-trucks sites. Trucks were estimated to contribute between 
5.0-14.2 [mu]g/m3 PM2.5, depending on the level 
of truck traffic.
    In a study by Indale (2004), investigators from the University of 
Tennessee-Knoxville and Oak Ridge National Laboratory conducted air 
quality monitoring and modeling at a large truck stop along a freight 
corridor outside Knoxville, TN. Continuous PM2.5 and 
NOX monitoring took place between December 2003 and 
September 2004. Monthly-averaged PM2.5 ranged from 27-40 
[mu]g/m3 within the truck stop, with the 98th percentile of 
daily values exceeding 65 [mu]g/m3. Regional background 
PM2.5 during the same interval was only 14 [mu]g/
m3. PM2.5 and NOX concentration within 
the truck stop tracked the number of idling trucks within the truck 
stop closely, which was highest at night. Hourly PM2.5 
concentrations within the truck stop averaged 10 [mu]g/m3 
greater than along the interstate highway 200 meters distant. EPA notes 
that the findings of this study are more relevant to how 
PM2.5 air quality would be affected by freight or bus 
terminals, as opposed to highway facilities servicing truck routes.
    Finally, in Brauer et al. (2003), investigators obtained 
``annualized'' average PM2.5 and black carbon at 40-42 
locations in each of three locations: The Netherlands (nationwide), 
Stockholm County (Sweden), and Munich, Germany. Monitoring consisted of 
samples taken 15 minutes of every hour over 4 two-week periods 
throughout a 17-month period, normalized to a central monitor. 
Locations consisted of ``traffic'' sites (>3,000 vehicles/day within a 
50 m radius), ``urban background'' sites, and rural sites. 
PM2.5 was 8-35% higher, and black carbon was 43-84% higher 
at ``traffic'' sites than at ``urban background'' sites. Using 
regression within each area of study, traffic intensity on roads within 
250 meters explained 30-40% of the variability in PM2.5, and 
54-70% of variability in black carbon. Traffic was the strongest 
explanatory variable in all statistical models.
    EPA notes that its understanding of the potential for 
PM2.5 hot-spots from transportation projects has evolved 
over the past three years. In the November 2003 proposal (68 FR 62713), 
EPA proposed options that would have required no PM2.5 hot-
spot analyses, or only analyses in limited cases--which reflected its 
understanding at that time of the limited potential for transportation-
related PM2.5 hot-spots. Most of the research studies that 
had been reviewed by late 2003 indicated that concentrations of some 
components of PM2.5 increased near heavily traveled 
roadways. EPA considered at that time that many of these studies did 
not measure PM2.5 directly, but rather, considered 
concentrations of some components of PM2.5, such as BC and 
ultrafine particles.
    In proposing additional options in the December 2004 supplemental 
proposal after receiving public comment, EPA considered additional 
studies and reconsidered some of its previous statements from the 
November 2003 proposal. For example, EPA now believes that the 
information considered in the November 2003 proposal as well as the 
most recent information available does indicate a potential for higher 
localized emissions and PM2.5 concentrations near certain 
transportation facilities. Since November 2003, EPA has considered how 
information underlying previous statements was developed, including how 
localized emissions increases and existing background concentrations 
relate to the potential for localized violations of the 
PM2.5 standards.
    Furthermore, EPA had stated in the November 2003 proposal that 
PM2.5 monitoring data available at that time indicated that 
PM2.5 air quality problems were similar to ozone in that 
they are both primarily regional in nature, which the Agency now 
believes was an incomplete assessment of the broader PM2.5 
air quality problem. EPA now believes that PM2.5 is both a 
regional and a localized air quality concern in certain circumstances. 
While it is true that secondary formation from PM2.5 
precursors is a critical component to the regional PM2.5 air 
quality problem, directly emitted PM2.5 from certain local 
sources has the potential to cause or contribute to elevated localized 
PM2.5 concentrations. Such elevated concentrations which 
exceed applicable standards can have an effect on local communities and 
populations that the PM2.5 standards were designed to 
protect.
    In the December 2004 supplemental proposal, EPA considered 
additional scientific studies and requested public comment on our 
assessments of such studies. For example, EPA highlighted a new study, 
Burr, et al., (2004), which examined changes in traffic patterns 
associated with a single transportation project that can result in 
statistically significant differences in PM2.5 mass 
concentrations measured along affected roadways. The results of this 
study highlight changes in PM2.5 concentrations along 
roadways resulting from changes in local traffic patterns, rather than 
changes in regional PM2.5 emissions.
    While originally believed to be a predominantly regional pollutant, 
subsequent analyses of EPA's PM2.5 monitoring data reveal 
the influence of both regional and local sources. Pinto et al. (2004) 
reviewed monitoring data from 1999 to 2001 from 27 urban areas 
nationally. This study showed that differences in annual means between 
monitors within a city often reached 5 [mu]g/m3 or higher, 
reflecting the possible influence of local sources in many areas, in 
addition to variations in meteorology and terrain. Although this study 
does not specifically address transportation sources, the study 
highlights the importance of subregional sources that impact local 
PM2.5 air quality.
    Finally, EPA has considered all of the information that commenters 
have provided in response to the November 2003 and December 2004 
proposals. EPA received a range of information from commenters, such 
as:
     Broad observations for targeting PM2.5 hot-spot 
requirements;
     General discussions about monitoring data gathered to date 
on PM2.5 hot-spots;
     Narrative, non-technical descriptions of an individual 
PM2.5 area's considerations for potential PM2.5 
hot-spots;
     Examples of state and local regulations that target 
potential PM2.5 hot-spots from transportation projects; and,
     Plans by individual states and nonattainment areas to 
conduct studies on the existence of PM2.5 hot-spots.
    This and other information received from commenters is included in 
the docket for today's final rule. We will further consider these and 
other state and local information in the development of our future 
quantitative PM2.5 hot-spot modeling guidance and 
implementation for this final rule.
    Feasibility and resource implications: EPA also considered whether 
or not the final rule's requirements were feasible and practical. For 
example, is the

[[Page 12474]]

information needed to implement an option available? Do state and local 
agencies have the methods and experience to implement an option in a 
reasonable time frame? EPA considered these and other questions, so 
that meeting statutory requirements was assured to be completed in an 
efficient manner. EPA rejected options that could not be feasibly 
implemented.
    Targeting projects of air quality concern and not requiring 
qualitative hot-spot analyses for projects that are not of concern will 
streamline project-level conformity determinations in PM2.5 
areas, since many proposed projects in transportation plans and TIPs 
are not expected to be of air quality concern. Allowing DOT to make 
categorical hot-spot findings will provide another opportunity to 
further narrow the focus of quantitative analyses for those projects 
that matter significantly for air quality. All of these aspects of the 
final rule will utilize state and local resources in an efficient and 
reasonable manner while still satisfying Clean Air Act requirements. 
See Sections V. and VII. for further rationale and responses to 
comments on criteria for projects of air quality concern and 
categorical hot-spot findings.

D. Response to Comments on Proposed PM2.5 Hot-spot Options

    EPA received comments on the proposed options for PM2.5 
areas from state and local transportation and air quality agencies, 
environmental groups, transportation advocates, and the general public. 
Certain general trends were evident where the same commenters supported 
similar options during the time periods before and after a 
PM2.5 SIP is submitted. In general, commenters who supported 
finalizing no or limited PM2.5 hot-spot requirements prior 
to PM2.5 SIP submission (Options 1, 2, or 5) also generally 
supported options that would have no hot-spot requirement at all 
(Option A) or rely on the SIP to identify hot-spot requirements (Option 
B) after PM2.5 SIP submission. Similarly, commenters who 
supported applying the existing PM10 hot-spot requirements 
prior to PM2.5 SIPs (Options 3 or 4), also supported doing 
the same after PM2.5 SIPs are in (Option C). In addition, 
there were commenters who believed either that EPA should delay 
finalizing a PM2.5 hot-spot requirement at this time, or 
that EPA should modify the proposed options so that they are more 
environmentally protective. The following paragraphs describe these and 
other comments that EPA considered in the development of the final 
rule, and EPA's responses to those comments.
Comment
    Many commenters supported finalizing PM2.5 hot-spot 
requirements that were consistent with the previous conformity rule's 
provisions for PM10 areas (i.e., Options 3 and C), to meet 
Clean Air Act requirements and protect public health. Commenters 
supported these options because they believed that these options would 
promote consistency with EPA's past legal interpretations regarding how 
federally funded and approved transportation projects met Clean Air Act 
section 176(c)(1)(B) requirements in PM10 areas. Commenters 
believed that it was reasonable to expect that transportation projects 
can cause PM2.5 hot-spots, and that conducting project-level 
PM2.5 hot-spot analyses would provide an environmental 
benefit by characterizing emissions impacts and considering mitigating 
approaches. These commenters also argued that the available scientific 
studies and research demonstrate that all transportation projects, 
including highway and transit projects involving significant diesel 
traffic, have the potential to create PM2.5 hot-spots.
    EPA also received many comments, including over 5,000 form e-mail 
comments from private citizens, expressing concerns about many of the 
proposed options that would require no or limited PM2.5 hot-
spot analyses (e.g., Options 1, 2, 5, A, and B), which they believed 
did not go far enough in protecting public health. These commenters 
were very concerned that all transportation projects, especially major 
highway projects, be evaluated for local PM air quality impacts on 
people living in neighborhoods before these projects receive Federal 
approval or funding. The commenters believed that EPA should consider 
the severity of PM2.5 impacts on the health and welfare of 
adults who work, children who play, and families living in 
neighborhoods near heavily traveled highways. The commenters indicated 
that these populations are at increased risk of suffering from serious 
health effects from PM2.5, including asthma, heart disease, 
lung cancer, and associated premature death. Other commenters also 
cited studies on the serious health effects caused by high 
PM2.5 concentrations, and believed that requiring 
PM2.5 hot-spot analyses for all projects best protects the 
public health for citizens in PM2.5 areas, especially 
vulnerable populations living near proposed transportation projects.
    On the other hand, many other commenters supported options that 
would apply no or only limited PM2.5 hot-spot requirements 
(i.e., Options 1, 2, 5, A, and B), and some preferred that EPA delay 
issuing final PM2.5 hot-spot requirements until certain 
issues are addressed. These commenters believed that there was 
insufficient evidence regarding the existence and prevalence of 
PM2.5 hot-spots. Commenters stated that their preferences 
would be appropriate because PM2.5 is a new pollutant that 
should be further examined at the national and local level before more 
rigorous PM2.5 hot-spot requirements are finalized. Some 
commenters argued that PM2.5 hot-spot requirements are not 
required by the Clean Air Act at all, and therefore, no such 
requirements should ever be finalized in EPA regulations.
    Other commenters were opposed to requiring existing PM10 
hot-spot requirements in PM2.5 areas (under Options 3 and C) 
because they believed these options would require extensive analyses 
without comparable environmental benefits and flexibility. These 
commenters believed it was unnecessary and excessive to require hot-
spot analyses for every project in every PM2.5 nonattainment 
area. Commenters argued that more research is needed to better define 
the situations where hot-spots may be a concern, and how individual 
projects could impact air quality standards under different air quality 
circumstances. Some of these commenters also argued that EPA has not 
demonstrated why performing PM2.5 hot-spot analyses would be 
beneficial to attaining the PM2.5 standards.
Response
    EPA believes that the final rule addresses many of the concerns 
raised by commenters. As described above, EPA concludes that the final 
rule allows all projects in PM2.5 areas to meet Clean Air 
Act section 176(c)(1)(B) requirements during the time periods both 
before and after a PM2.5 SIP is submitted. EPA believes that 
today's final rule is consistent with its past legal interpretations 
for applying hot-spot requirements for projects of air quality concern.
    However, EPA disagrees with commenters who argued that there is not 
enough information at this time to apply a PM2.5 hot-spot 
requirement. Based on our review of scientific studies and information 
gathered during the rulemaking process, as described above, EPA 
believes that there is compelling evidence that certain transportation 
projects of air quality concern have the potential to impact localized 
PM2.5 concentrations. Such impacts, if they would create or 
worsen violations for the PM2.5 standards on communities

[[Page 12475]]

surrounding a project of air quality concern, would be contrary to the 
Clean Air Act's conformity requirements. Furthermore, EPA does not 
agree that it is appropriate to delay finalizing a PM2.5 
hot-spot requirement for such projects until certain comments are 
addressed, for the reasons cited above.
    EPA notes again, as described further elsewhere in this notice, 
that projects which do not represent a localized air quality concern 
can be presumed to meet Clean Air Act requirements and 40 CFR 93.116 
without any explicit hot-spot analysis. This aspect of the final rule 
is expected to streamline PM2.5 hot-spot requirements and 
use state and local resources efficiently.
Comment
    EPA also proposed Options 2 and B that relied solely on the SIP to 
identify projects or project locations of potential PM2.5 
hot-spot concern. Under these options, quantitative PM2.5 
hot-spot analyses would only be required at types of project locations 
identified as a localized air quality concern in a given 
PM2.5 SIP. No quantitative or qualitative analyses would be 
required for projects in other types of locations, or in 
PM2.5 areas where the SIP does not identify types of 
locations as a localized PM2.5 air quality concern. 
Furthermore, no hot-spot analyses would be required for any projects in 
PM2.5 areas prior to PM2.5 SIP submission.
    Many commenters supported these options. Some commenters believed 
that the existence and prevalence of PM2.5 hot-spots was 
uncertain and that the SIP process could assist in identifying what 
projects are of concern in a given area and consequently what level of 
PM2.5 hot-spot analysis is appropriate. Commenters opined 
that Options 2 and B would allow each PM2.5 area to better 
target potential PM2.5 hot-spots and protect the public 
health of their citizens, since the SIP is the appropriate mechanism 
for addressing state and local air quality goals. These options were 
considered by some to provide the necessary flexibility in implementing 
hot-spot requirements both before and after a PM2.5 SIP is 
submitted.
    In contrast, other commenters believed that Options 2 and B would 
not meet Clean Air Act requirements or protect public health. First, 
such commenters indicated that Option 2 would eliminate any requirement 
to perform PM2.5 hot-spot analyses prior to the development 
of a PM2.5 SIP, which would not meet statutory requirements 
that apply during this time period. These commenters argued that 
PM2.5 emissions impacts resulting from transportation 
projects should be assessed and mitigated as part of the conformity 
process at all times, and that such projects if not analyzed could 
significantly degrade air quality and increase the number and severity 
of local PM2.5 violations in the time period prior to SIP 
submission.
    Second, several commenters believed that this option may not be 
feasible in every area because it is unlikely that there is adequate 
data to identify exact locations of local concern in the SIP. This 
could be due to the absence of data or lack of specificity of existing 
data regarding PM2.5 hot-spot locations. Some argued that 
this may be the case due to placement of current monitors away from 
large transportation projects, or the focus on the annual 
PM2.5 standard rather than the 24-hour PM2.5 
standard in SIP development. One commenter believed that 
PM2.5 air quality monitors have historically been located 
more than the 300 feet from where highway projects would have their 
major impact on PM2.5 concentrations.
    Third, commenters were concerned that Option B would place an 
inequitable burden on state and local air agencies that are already 
tasked with developing PM2.5 SIPs to meet other Clean Air 
Act requirements. PM2.5 SIPs are statutorily required to be 
submitted three years from the effective date of PM2.5 
nonattainment designations (i.e., April 5, 2008). Unless possible 
PM2.5 hot-spot locations are well-defined and based on 
developed and verified monitoring data, one commenter argued, it would 
be inappropriate at this time to solely rely on PM2.5 SIPs 
to implement conformity requirements.
    Although two commenters supported the consideration of 
PM2.5 hot-spots in the SIP process, they did not agree that 
solely relying on that process met Clean Air Act conformity 
requirements, for the reasons described above. In addition, these 
commenters argued that it is uncertain whether PM2.5 SIPs 
will be developed on time, based on past history of SIP submissions.
    Finally, some commenters were skeptical regarding whether the SIP 
process was the appropriate forum for identifying transportation-
related hot-spots. These commenters believed that there is no legal 
obligation under the Clean Air Act to identify project locations of air 
quality concern in the SIP. They argued that Option B was deficient 
because states may choose not to identify potential hot-spot locations 
either because sufficient data is not available or out of concern that 
conformity requirements would apply. These commenters also believed 
that air agencies had a poor historical record of developing 
appropriate PM10 SIPs, and that it was unclear whether EPA 
would be willing or able to remedy any PM2.5 SIPs that did 
not identify transportation-related PM2.5 hot-spot 
locations.
Response
    EPA is not finalizing Options 2 and B because these options do not 
sufficiently address all of the factors outlined in the December 2004 
supplemental proposal and today's final rule:
     The Clean Air Act conformity requirements for individual 
transportation projects;
     The current scientific understanding of PM2.5 
hot-spots and public health effects;
     The feasibility of implementing options; and
     The impact on state and local resources.
    EPA has reached this conclusion based on consideration of all of 
the information gathered during the rulemaking process.
    EPA has already stated that any option that is finalized must 
ensure that all federally funded and approved transportation projects 
in PM2.5 areas are consistent with Clean Air Act section 
176(c)(1)(B). As stated in the December 2004 proposal, to meet this 
provision under Option 2, we would need to conclude that it was 
necessary to wait until the SIP is developed to understand the 
potential air quality impacts of projects in any PM2.5 area. 
EPA is unable to support such a conclusion based on our current 
scientific understanding of transportation-related PM2.5 
hot-spots, as described in C. of this section. Delaying the application 
of a PM2.5 hot-spot requirement until SIPs are submitted 
would not ensure that new projects of air quality concern do not cause 
or contribute to any new PM2.5 violations, worsen any 
existing violations, or delay timely attainment prior to SIP 
submission.
    EPA originally proposed Option B in November 2003 because the 
potential for transportation-related PM2.5 hot-spots was not 
clearly understood at that time. Rather than not establish any 
PM2.5 hot-spot requirement due to the scientific uncertainty 
regarding PM2.5 hot-spots, EPA proposed an alternate option 
to allow states to identify project locations of concern through the 
SIP development process, when information for potential 
PM2.5 hot-spots was available. After considering other 
scientific information, EPA revisited Option B in its December 2004 
supplemental proposal, and provided new options to more broadly 
evaluate

[[Page 12476]]

the potential for PM2.5 hot-spots from transportation 
sources.
    EPA also presented a possible legal argument in the November 2003 
and December 2004 proposals that Option B may be consistent with the 
purpose of conformity to ensure that federally funded or approved 
transportation projects are consistent with the SIP in a given 
nonattainment or maintenance area. Section 176(c)(1)(A) requires 
``conformity to an implementation plan's purpose of eliminating or 
reducing the severity and number of violations of the national ambient 
air quality standards and achieving expeditious attainment of such 
standards * * *.'' However, EPA has now determined that Clean Air Act 
section 176(c)(1)(B) requiring that projects not create or worsen NAAQS 
violations is the applicable legal standard for this final rule. This 
legal standard could only be met if PM2.5 SIPs would be 
developed that identify all potential project locations of air quality 
concern for any such project proposed in the transportation plan or TIP 
for years to come.
    In the December 2004 supplemental proposal, EPA further considered 
the feasibility of implementing Option B, as to whether sufficient 
information existed to allow a state to specify all susceptible 
locations where PM2.5 hot-spots are an air quality concern. 
We acknowledged that there may be cases where it is unclear whether 
susceptible locations for hot-spots exist, or where there is a 
potential for localized PM2.5 violations but it is difficult 
to specify which project locations could create hot-spots. EPA also 
requested comment on how the proposed options should be implemented in 
cases where the latest information available on the potential for 
PM2.5 hot-spots is not reflected in the PM2.5 
SIP.
    EPA concludes there are other reasons to believe that Option B does 
not meet Clean Air Act conformity requirements. SIPs are generally 
developed to meet regional air quality concerns that are more in 
parallel with the regional emissions analysis for plan and TIP 
conformity determinations. As such, EPA does not anticipate requiring 
PM2.5 SIP modeling to be performed at a level of detail that 
would identify all potential transportation hot-spots. There are also 
concerns regarding the ability of the SIP to evaluate the local air 
quality impacts of all future projects, even those that are not even 
identified during and after the SIP's development. And finally, it is 
unclear how EPA would enforce a conformity requirement like Option B if 
SIPs do not identify hot-spot concerns when appropriate.
    Based on all of these considerations and the comments received, EPA 
does not believe that it is realistic or practical to expect that 
Option B which bases hot-spot analysis requirements solely on the SIP 
can be sufficiently implemented to meet statutory requirements in all 
PM2.5 areas.
Comment
    A few commenters also argued that EPA may not lawfully finalize 
options that defer PM2.5 hot-spot analyses until after a SIP 
is submitted because such delays are inconsistent with Clean Air Act 
requirements. The commenters cited several legal arguments. First, 
commenters believed that where a SIP of any kind exists, Clean Air Act 
section 176(c)(1) does not require that a state must first have adopted 
a SIP for a given standard before the conformity requirements for that 
standard apply.
    These commenters also argued that the statute requires conformity 
to apply as soon as the one-year conformity grace period expires for 
areas that have Clean Air Act section 110 SIPs in effect. Unless, EPA 
finds that an area lacks a section 110 SIP (which is not the case for 
any area), they believed that conformity determinations that meet all 
statutory requirements are required for projects in areas that have 
previously been designated nonattainment for PM2.5, even if 
they were not previously PM10 nonattainment or maintenance 
areas.
    Furthermore, the commenters stated that the one-year conformity 
grace period does not even apply to PM2.5 nonattainment 
areas that have been previously designated nonattainment for the 
PM10 air quality standards. These commenters believed that 
the grace period does not apply if an area is designated nonattainment 
for a new or revised standard for the same criteria pollutant, in this 
case, the standards for PM2.5 are for the same pollutant as 
for PM10 (i.e., particulates). The commenter cited EPA's 
1997 rulemaking that promulgated the PM2.5 standards, in 
which EPA rejected arguments that PM2.5 was a new pollutant 
that required listing under Clean Air Act section 108 prior to adopting 
a new standard. The commenter also referred to the DC Circuit decision 
that held that PM2.5 has always been regulated as a fraction 
of PM10 and that EPA was not required to list 
PM2.5 as a new pollutant. American Trucking Assns v. U.S. 
EPA, 175 F.3d 1027, 1055 (DC Cir. 1999).
Response
    As explained above, EPA agrees that it is not appropriate to defer 
project level hot-spot analyses until SIPs are developed, and thus has 
not chosen these proposed options in the final rule. EPA also agrees 
that all conformity requirements apply one year after an area is newly 
designated nonattainment with respect to a given NAAQS if the state has 
a general section 110 SIP. To that end, conformity will apply in 
PM2.5 nonattainment areas as of April 5, 2006, since all 
areas of the country do have section 110 SIPs. PM10 
nonattainment areas continue to be subject to conformity requirements 
applicable to the PM10 standards, which are covered by this 
final rule and our existing conformity regulations.
    However, EPA disagrees with the commenter's assertion that the one-
year conformity grace period for newly designated nonattainment areas 
does not apply for PM2.5 nonattainment areas that are also 
PM10 nonattainment or maintenance areas. The grace period is 
clearly applicable by its own terms to an area for one year after it is 
first designated nonattainment for a specific standard. The grace 
period would apply for all new standards, even if they are different 
standards for the same pollutant. Section 176(c)(6) states, 
``Notwithstanding paragraph 5, this subsection shall not apply with 
respect to an area designated nonattainment under section 107(d)(1) 
until 1 year after that area is first designated nonattainment for a 
specific national ambient air quality standard. This paragraph only 
applies with respect to the national ambient air quality standard for 
which an area is newly designated nonattainment and does not affect the 
area's requirements with respect to all other national ambient air 
quality standards for which the area is designated nonattainment or has 
been redesignated from nonattainment to attainment with a maintenance 
plan pursuant to section 175A (including any pre-existing national 
ambient air quality standard for a pollutant for which a new or revised 
standard has been issued).'' (Emphasis added). The statute thus 
expressly differentiates between new and existing standards for a given 
pollutant, and specifically provides the grace period for new standards 
that may apply for the same pollutant. EPA does not believe there is 
any ambiguity in the applicability of the grace period under the 
statute. EPA acknowledges that PM2.5 and PM10 are 
both standards applicable to particulate matter, but concludes that 
given the express language of the statutory grace period there is no 
question that it applies to newly designated PM2.5 
nonattainment areas. In addition, the grace period for PM2.5 
will terminate in April 2006, so

[[Page 12477]]

any concerns about this issue will become moot at that point.
Comment
    EPA also requested comment on how Option B should be implemented in 
cases where the latest information available on the potential of 
PM2.5 hot-spots is not reflected in the SIP (December 13, 
2004; 69 FR 72148). Such cases would result if information becomes 
available outside the SIP process that indicates that there may be 
potential transportation-related hot-spot locations. Some commenters 
were concerned that it may not be possible to identify all types of 
projects or locations that could be an air quality concern in the time 
addressed by the SIP or in future years. New projects of air quality 
concern that are not addressed by a SIP, the commenter argued, should 
require a PM2.5 hot-spot analyses to protect public health.
Response
    EPA considered the concerns raised by commenters. In developing the 
final rule, EPA considered the ability of all PM2.5 SIPs to 
identify every project of air quality concern in the timeframe of the 
SIP and future years, and how such projects at locations not identified 
in the SIP could meet Clean Air Act conformity requirements without a 
PM2.5 hot-spot analysis. EPA did not finalize Option B in 
the final rule, since the Agency concluded that it is unreasonable to 
believe that all projects of air quality concern would be identified by 
the SIP and therefore required to comply with the conformity provisions 
of the Clean Air Act.
Comment
    Some commenters were concerned that the final rule use state and 
local resources effectively. These commenters, however, differed in 
their reasons for supporting various options. First, some commenters 
were concerned that finalizing requirements that required 
PM2.5 hot-spot analyses for all projects (Options 3 and C) 
could result in an inefficient use of state and local resources that 
could be used for SIP development, and additional monitoring of the 
potential and location for PM2.5 hot-spots. A few commenters 
acknowledged that many agencies are also addressing conformity for the 
8-hour ozone standard, which takes away resources for PM2.5. 
Other commenters stated that agencies will not have PM2.5 
data, such as monitoring data and inventory estimates, until SIPs are 
developed or maybe not at all. These commenters stated that the 
majority of PM2.5 monitors have been in place for less than 
five years and many do not collect speciated data, which they believed 
is critical to pinpointing likely sources of PM2.5. Other 
commenters supported not requiring any PM2.5 hot-spot 
analyses (Options 1 and A) or delaying the final rule altogether, which 
would allow state and local agencies to focus resources on other 
planning and SIP efforts.
    Other commenters believed that a more effective use of resources 
would be to identify PM2.5 problem locations during the SIP 
development process (through Options 2 and B), which would allow state 
and local agencies to determine if and where hot-spot analyses would 
apply. The SIP process allows states and regions to acquire necessary 
data and research which allows for more conclusive information. All of 
these commenters believed that focusing PM2.5 hot-spot 
requirements on PM2.5 air quality problem areas and 
potential sources that matter would better use limited state and local 
resources.
    However, other commenters believed that the options involving no 
hot-spot analyses or tying hot-spot analyses to SIPs (Options 1, 2, A, 
and B) would not protect public health since these options would 
eliminate or narrow any requirement to perform PM2.5 hot-
spot analyses. Furthermore, some commenters believed that options that 
were consistent with the existing PM10 hot-spot requirements 
(Options 3 and C) would be easier to implement for areas with previous 
CO or PM10 hot-spot analysis experience. Two commenters 
further stated that these options would be more consistent with how 
their state is already considering PM2.5 localized impacts 
under state environmental requirements.
Response
    EPA believes that the final rule will ensure that state and local 
resources are used in an efficient manner, since hot-spot analyses will 
only be required for projects of air quality concern. Eliminating 
qualitative analyses for projects that are not an air quality concern 
based on EPA's conclusion that such projects will not create or worsen 
air quality violations will significantly reduce any challenges in 
implementing this final rule, since the majority of projects that are 
usually proposed are not projects of air quality concern. Therefore, 
most project-level conformity determinations will not contain a hot-
spot analysis of any kind, since most projects are not in danger of 
impacting the PM2.5 standards.
    As noted above, EPA concludes that requirements keyed only to SIP 
development may not assure conformity of all projects and thus believes 
it cannot address the resource issue through such options. However, EPA 
believes that requiring analyses only for projects of air quality 
concern will both ensure that all projects meet the statutory 
requirements and provide sufficient resources to conduct all necessary 
analyses.
    EPA agrees that there are start-up issues that some state and local 
agencies will need to overcome, especially areas without previous 
experience in implementing a hot-spot requirement in CO or 
PM10 areas. However, EPA and DOT's qualitative hot-spot 
guidance, and our future quantitative hot-spot modeling guidance for 
projects of air quality concern will assist in the implementation of 
this final rule. As always, EPA will continue to, in cooperation with 
DOT, work to assist state and local agencies in implementing the final 
rule's requirements.
    Finally, EPA would like to address the comment that further 
PM2.5 monitoring data needs to be gathered before applying a 
hot-spot requirement. EPA disagrees with this comment. There is 
sufficient evidence that projects of air quality concern can affect 
local PM2.5 concentrations, and therefore, waiting for 
additional monitoring data used in SIP development for every 
PM2.5 area is not necessary to meet statutory conformity 
requirements now. Also, EPA believes that PM2.5 hot-spot 
analyses can be completed for projects of air quality concern even if 
PM2.5 monitoring data is not available for a given project's 
location. EPA will clarify in its future quantitative hot-spot modeling 
guidance how monitoring data of current and past PM2.5 air 
quality can be used in estimating future PM2.5 air quality 
concentrations.
Comment
    Other commenters were concerned that EPA has not yet issued 
PM2.5 quantitative hot-spot analysis guidance and methods. 
Some commenters supported doing little or no hot-spot analyses, in part 
because they asserted that credible tools are not currently available 
and quantitative analyses would not be required until guidance were 
available, possibly just before the April 5, 2008 PM2.5 SIP 
deadline. However, other commenters believed that all of the proposed 
options were insufficient since they would delay quantitative 
PM2.5 hot-spot analyses for years, and in the interim, there 
would be no consideration of the public health impacts of projects 
currently under development.

[[Page 12478]]

    Finally, some commenters believed that EPA needed to issue 
qualitative PM2.5 hot-spot guidance, since the existing 
PM10 qualitative hot-spot guidance was not applicable to 
PM2.5 hot-spot analyses. These commenters noted that 
PM2.5 is chemically different than PM10 and most 
of the PM2.5 areas are violating the annual PM2.5 
standard, whereas most PM10 areas were constrained by the 
24-hour PM10 standard.
Response
    Today's final rule extends Sec.  93.123(b)(4) of the existing 
conformity rule's PM10 hot-spot provisions to 
PM2.5 areas. This provision now requires that quantitative 
PM2.5 hot-spot analyses be performed once EPA announces in 
the Federal Register that quantitative analysis requirements are in 
effect. EPA has not yet made such an announcement because the Agency 
has not approved appropriate motor vehicle emissions factor models for 
localized analyses, and EPA is in the initial stages of developing 
quantitative PM2.5 and PM10 modeling guidance to 
apply existing air quality dispersion models and future emissions 
factor models to implement today's rule. Please see Section VI. of 
today's final rule for further information on the timing of 
quantitative hot-spot requirements.
    EPA agrees that the existing PM10 qualitative hot-spot 
guidance is not applicable to PM2.5 analyses. As a result, 
EPA and DOT have developed qualitative PM2.5 hot-spot 
guidance for immediate use for conformity determinations for projects 
of air quality concern, which is available at the Web site listed in 
Section I.B.2. of today's action.
Comment
    Some commenters believed that EPA could improve on its proposed 
options in the final rule. Some examples of commenters' suggestions are 
as follows:
     Clarifying or expanding the list of projects for which 
quantitative analyses are to be conducted;
     Adopting a screening method or emissions threshold that 
would help define what projects require quantitative hot-spot analyses; 
and,
     Allowing both the MPO and state or local air agency to 
have the opportunity to identify further projects that should undergo 
quantitative review.
    The screening procedure is necessary, one commenter believed, to 
avoid unnecessary effort associated with PM2.5 hot-spot 
analyses and project-level conformity determinations. Still another 
commenter believed that any hot-spot requirement should be limited in 
geographic scope to those parts of the nonattainment area where 
monitors indicate that PM2.5 levels are above a standard or 
forecasts indicate they are projected to reach such levels.
Response
    EPA has responded to similar comments in other sections of today's 
action. The final rule addresses many of the suggestions submitted by 
commenters by further defining what projects need hot-spot analyses to 
meet statutory requirements and conserve resources. See Section V. for 
further information on the regulatory criteria for quantitative hot-
spot analyses. The elimination of qualitative hot-spot analyses for 
many projects in part addresses the motivation for a screening method 
or emissions threshold--i.e., to focus more rigorous quantitative 
analyses on projects of air quality concern.
    EPA also agrees that the air quality circumstances can be 
considered in further narrowing the focus of quantitative hot-spot 
analyses. See Section VII. of this notice for further discussion on how 
such information could be considered for future categorical hot-spot 
findings.
Comment
    EPA also proposed Option 4 and 5 for the time period before 
PM2.5 SIPs are submitted. Two commenters preferred Option 4 
which allowed for a finding that hot-spots were not of air quality 
concern to any other pre-SIP option. One of these commenters preferred 
Option 4 because it offered the best combination of conformity review 
continuity and flexibility in determining which projects required 
PM2.5 hot-spot analyses. The commenter argued that its state 
needed to have PM2.5 hot-spot analyses prior to 
PM2.5 SIP submission because many transportation projects 
would be developed during this time period that could negatively impact 
air quality. Allowing for a ``grace period'' before project impacts are 
considered prior to SIP submission could increase hot-spot emissions, 
the commenter argued. All of these commenters, however, agreed that 
Option 4 was consistent with past practice for applying PM10 hot-spot 
requirements and meeting statutory requirements while providing some 
relief when EPA and the state air agency has information that 
PM2.5 hot-spots are not a concern in a given area. On the 
other hand, other commenters did not support Option 4 for the same 
reasons that they did not support Option 3, which are described in a 
previous summary.
    Some commenters supported Option 5 because they believed that this 
option reflected the current state of scientific understanding, used 
resources efficiently, addressed the learning curve for areas without 
PM experience, and relied on future development of PM2.5 
SIPs. Option 5, commenters argued, is appropriate because it provided 
an opportunity for each PM2.5 area to tailor its hot-spot 
requirements when information exists prior to PM2.5 SIP 
submission. However, other commenters stated specific opposition to 
Option 5; these commenters saw this option as a ``loophole'' for not 
protecting PM2.5 air quality, since it would presume that 
PM2.5 hot-spot analyses were not needed unless a finding was 
made. These commenters expressed doubt that such findings would be done 
at all in any PM2.5 area.
    EPA also requested comment on whether state and local air agencies 
will have the necessary data and other information to make the findings 
described for Options 4 and 5. Comments were mixed on this point. For 
example, three commenters who supported Option 5 believed that there 
would not be sufficient information regarding PM2.5 hot-spot 
potential prior to the development of a PM2.5 SIP in a given 
area. Other commenters who supported either Option 3 or 4 believed that 
there would be information to support making findings based on either 
existing air quality monitoring data, current state screening 
thresholds, or other techniques for what projects need PM2.5 
hot-spot analyses.
Response
    EPA originally proposed Options 4 and 5 because of what was seen at 
the time as the evolving nature of our understanding of 
PM2.5 air quality issues. These options would rely on the 
proposed interpretation stated in the November 2003 proposal (68 FR 
62713): Clean Air Act section 176(c)(1)(B) requirements could be met as 
long as explicit reviews are performed at locations identified in the 
PM2.5 SIP as susceptible to PM2.5 hot-spots. Both 
Options 4 and 5 were intended to allow EPA and states to target hot-
spot requirements in PM2.5 nonattainment areas where hot-
spots may or may not be an air quality concern.
    However, EPA is not finalizing these options either because they do 
not meet statutory requirements as explained above, or the final rule 
already provides the flexibility intended by the originally proposed 
options. In addition, EPA was not convinced based on the comments 
received that either option was feasible

[[Page 12479]]

in identifying all projects of air quality concern.
Comment
    There were a few commenters who believed that PM2.5 hot-
spot analyses would not be an efficient use of resources because of 
their individual PM2.5 nonattainment area's circumstances. 
Several commenters stated that it is inefficient to direct resources to 
PM2.5 hot-spot analyses when transportation may not be a 
significant contributor to the PM2.5 air quality problem in 
a given area, such as smaller areas or cities dominated by other PM 
sources (e.g., wood smoke from residential stoves, fireplaces or other 
forms of residential heating). Another commenter pointed out that the 
only exceedance of the 24-hour PM2.5 standard in his area 
was attributable to a fireworks display. This same commenter believed 
that transportation projects would not impact the annual 
PM2.5 standard, which the commenter stated was more relevant 
in most areas, or jeopardize the 24-hour standard.
    Another commenter believed that his state needed flexibility to 
consider through the SIP process and consultation the hot-spot concerns 
of its remote communities. Another commenter stated that hot-spot 
analyses for projects in non-urbanized areas are never justified 
because such projects lack the size and density to allow other modes to 
effectively serve travel needs. A failed conformity test in these areas 
would simply leave real highway problems unresolved, the commenter 
hypothesized.
    One commenter stated that local agencies, including the MPO, have 
little or no ability to implement or require control measures or make 
project design changes that could impact PM2.5 at the 
project level. Also, the commenter believed transportation agencies 
have no control over existing Federal diesel fuel and off-road 
standards.
Response
    EPA believes that today's final rule protects air quality and 
public health in PM2.5 areas and provide an option for areas 
where on-road motor vehicles are an insignificant regional and local 
contributor to an area's particulate matter problem. Today's final rule 
targets PM2.5 hot-spot analyses on the types of projects 
that are likely to cause or contribute to new or worsened 
PM2.5 violations. Specifically, the rule targets hot-spot 
analyses on those types of projects that result in significant 
increases in diesel vehicle traffic (and therefore emissions), which is 
likely to be a small subset of transportation projects in most areas. 
In addition, the final rule's minor addition to 40 CFR 93.109(k) will 
allow PM2.5 areas with insignificant regional emissions to 
also demonstrate, when appropriate, that individual transportation 
projects will not create new localized violations or make existing 
violations worse.
    For example, isolated rural PM2.5 areas where other 
types of sources such as wood stoves or fireplaces are dominant at the 
regional level would only be required to perform hot-spot analyses for 
the types of projects described in Sec.  93.123(b) until such time as a 
PM2.5 SIP is submitted which demonstrates that regional on-
road motor vehicle PM2.5 emissions are insignificant and 
will not cause new or worsen existing local violations. EPA also notes 
that the impact of the final rule may be minimal in such smaller areas, 
since areas that are dominated by other sources do not typically have 
complex transportation systems needing new project approvals prior to 
PM2.5 SIP submission.\5\
---------------------------------------------------------------------------

    \5\ April 2003, Transportation/Air Quality Issues in Rural 
Areas, FHWA and Dye Management Group; and October 2003, Rural 
Conformity: A Survey of Practice, NCHRP Project 08-36, Task 28, 
prepared by ICF Consulting and Sarah J. Siwek and Associates.
---------------------------------------------------------------------------

    After EPA makes an adequacy finding (or approves) a SIP that 
demonstrates insignificant regional and local emissions, 
PM2.5 hot-spot analyses, would no longer be required in that 
area. EPA discussed its process for evaluating SIPs that claim 
insignificant regional and localized emissions in the June 30, 2003 
proposal (68 FR 38984) and July 1, 2004 final rule (69 FR 40061-40063). 
EPA Regions and states can work together to appropriately expedite the 
processing of such SIPs through such methods as parallel processing or 
direct final rulemaking.
    With regard to the concerns expressed about the appropriateness of 
hot-spot analyses in remote or non-urbanized areas, EPA would like to 
point out that today's final rule limits the need for PM2.5 
hot-spot analyses to only those projects which significantly increase 
diesel vehicle traffic and emissions. As noted above, this is likely to 
be only a small percentage of projects in remote or non-urbanized 
areas.
    With regard to the comment concerning the ability of MPOs to 
influence the design of individual projects and the ability of 
transportation agencies to have control over Federal diesel fuel 
standards and non-road equipment emissions standards, EPA would like to 
point out that in most cases hot-spot analyses are completed by project 
sponsors during the project's environmental review phase. Project 
sponsors are often state departments of transportation which do have 
the ability to modify project designs or take other steps to mitigate 
emissions from the individual project. While it is true that state and 
local transportation agencies cannot influence national diesel fuel 
standards, the state and local agencies can be assured that EPA is 
implementing these standards as planned and that the diesel sulfur 
standard and heavy duty engine rule will be phased in beginning in 
2007.
    With regard to the comment on national non-road emissions 
standards, the commenter is correct that state and local transportation 
agencies do not have control over such standards. EPA notes that non-
road emissions are considered to the extent that they are expected to 
impact background concentrations in PM2.5 hot-spot analyses 
of on-road highway and transit projects of air quality concern. EPA's 
future modeling guidance will address how background concentrations are 
to be calculated for quantitative hot-spot analyses.
Comment
    A few commenters argued that EPA's standards for low sulfur diesel 
fuels in 2006 and heavy-duty engines in 2007 will negate any need for 
PM2.5 hot-spot analyses. The commenters stated that EPA 
should analyze the impacts of these Federal standards on local air 
quality before PM2.5 hot-spot analysis requirements are 
finalized.
Response
    In the December 2004 supplemental proposal (69 FR 72147), EPA 
committed to consider the impact of the new diesel fuel and engine 
standards (January 18, 2001, 66 FR 5002) in the development of the 
final rule. Such standards are expected to significantly impact the 
amount of particulate emissions that will be emitted by new diesel 
vehicles, and consequently may impact the potential for 
PM2.5 transportation-related hot-spots. EPA considered the 
time frame over which these vehicle standards would phase in. According 
to the latest Vehicle Inventory and Use Survey from the Census 
Bureau\6\, in 2002, vehicles three years of age and younger constituted 
only 32.3% of U.S. truck fleet. If the same age distribution holds for 
2010, only about one third of trucks on the road will meet the heavy-
duty engine emissions standards for 2007 and 2010. In this scenario, 
most trucks on the road will still be capable

[[Page 12480]]

of producing elevated concentrations of PM2.5. As such, 
EPA's new emission standards do not eliminate the need for considering 
PM2.5 hot-spots from transportation projects involving a 
significant number of diesel vehicles. However, consideration of EPA's 
diesel fuel and engine standards' impact on background air quality will 
be addressed as part of EPA's future quantitative modeling guidance and 
possibly in modeling used to support categorical hot-spot findings as 
described in Section VII. of today's notice.
---------------------------------------------------------------------------

    \6\ This information can be found at: http://www.census.gov/svsd/www/vius/products.html.
---------------------------------------------------------------------------

Comment
    One commenter mentioned that EPA has never required hot-spot 
analyses prior to SIP development for any other pollutants. The 
commenter stated that significant CO and PM10 conformity 
requirements were not effective until after inventory and air quality 
models were developed and tested, and SIPs were submitted. Agencies 
could build on SIP submissions and technical analyses to perform hot-
spot analyses. For PM2.5, the commenter was concerned that 
planning agencies will not have this technical information nor the 
necessary modeling tools and experience.
Response
    EPA disagrees with this comment. Hot-spot analyses have in the past 
been required in areas before SIPs were developed. In fact, Clean Air 
Act section 176(c)(3)(B)(ii) requires that before CO SIPs were 
developed, projects could only be found to conform if they eliminated 
violations or reduced the number or severity of violations. As a 
result, hot-spot modeling was required to determine whether or not 
violations were being eliminated or the severity or number of 
violations were being reduced.
    As part of today's rulemaking, EPA believes that scientific 
evidence supports the conclusion that certain types of projects, 
particularly those involving significant increases in diesel vehicle 
traffic and emissions, could cause new violations or worsen existing 
violations. Therefore, EPA could not finalize a regulation that solely 
relied on the SIP process to identify locations or types of projects 
that could cause new violations or worsen existing ones with no hot-
spot analyses being required before the submission of a SIP or no 
analyses being required if the SIP did not address this issue. The 
final rule does allow for the SIP to identify additional projects or 
project locations of concern; however, in the face of available 
scientific evidence concerning projects which could adversely effect 
localized air quality, EPA is required to establish hot-spot analysis 
requirements for the types of projects identified in Sec.  
93.123(b)(1).
    As discussed in this preamble, initially areas will be required to 
carry out qualitative analyses until such time as EPA announces in the 
Federal Register that quantitative analysis requirements are in effect. 
The quantitative requirements will not be put into effect until after 
EPA releases appropriate modeling guidance and the MOVES motor vehicle 
emission factor model is released, as described further in Section V. 
of today's action. EPA and DOT have developed guidance on how to 
complete qualitative hot-spot analyses during the period before 
quantitative analyses requirements are put into effect. This guidance 
will be posted on the website provided in Section I.B.2. of today's 
notice. Therefore, conformity implementers will have the tools and 
information necessary in order to carry out hot-spot analyses.
Comment
    Some commenters also noted that EPA acknowledged in its proposals 
that the science surrounding the new PM2.5 standards is 
ongoing. These commenters cited preamble language from the November 
2003 proposal that air quality data indicates that PM2.5 is 
a regional pollutant like ozone, and therefore PM2.5 hot-
spot analyses should not be required until there is scientific evidence 
of localized concerns, especially in areas where exceedances are 
dominated by sources emitting secondary rather than direct 
PM2.5 emissions.
Response
    EPA disagrees with this comment. As noted in C. of this section, 
EPA believes that directly emitted PM2.5 from transportation 
sources can be both a regional and local air quality concern. Based on 
an evaluation of more recent studies, EPA has concluded that certain 
types of projects could be of local air quality concern and therefore 
has finalized the rule to require hot-spot analyses for all such 
projects at all times.
Comment
    One commenter believed that future changes to the current 
PM2.5 air quality standards should be considered, especially 
if EPA selects any option involving identifying hot-spot concerns 
through the SIP. The commenter believed that future SIPs should be 
completed with respect to more protective PM2.5 standards. 
This commenter argued that more stringent PM2.5 standards 
could significantly increase the potential for transportation projects 
to cause or contribute to PM2.5 violations.
    Other commenters noted that existing PM2.5 standards 
were in process of being revised, or that the public health benefits of 
controlling hot-spots indicate that EPA consider more health-protective 
standards.
Response
    EPA did not finalize hot-spot analysis requirements that rely 
solely on an area's SIP to identify the types of projects or project 
locations that require a hot-spot analysis. However, EPA does not 
believe it is appropriate to address the remainder of these comments 
concerning the pending review of the current PM2.5 standards 
at this time.
    The commenters are correct that EPA is in the process of reviewing 
the current PM2.5 air quality standards. As required by 
consent decree, EPA proposed revisions to the current PM2.5 
air quality standards on January 17, 2006 (71 FR 2620). EPA is required 
to finalize this rulemaking by September 27, 2006. When reviewing an 
air quality standard, EPA considers available health effects data. As 
such EPA is considering any available health information related to 
localized elevated PM2.5 concentrations.
    EPA will consider the need to revise the conformity rule if 
appropriate after any changes to the PM2.5 standards are 
finalized. However, today's final rule protects air quality and public 
health in current PM2.5 nonattainment areas according to the 
current standards. This is accomplished by ensuring that projects that 
are likely to cause new or worsen existing violations with respect to 
the currently applicable standards undergo a hot-spot analysis before a 
project-level conformity determination is made.
Comment
    EPA invited commenters to submit studies or data regarding 
PM2.5 hot-spots during the comment period for the December 
2004 supplemental proposal. Comments varied regarding whether or not 
transportation projects could impact the level and forms of the current 
PM2.5 standards at the local level.
Response
    EPA reviewed the information submitted by these commenters along 
with a large number of other studies as discussed above. Based on a 
review of all of the data, EPA concluded that certain types of 
individual transportation projects, particularly

[[Page 12481]]

those which significantly increase diesel vehicle traffic and 
emissions, could lead to new violations or could worsen existing 
violations of either the current annual or 24-hour form of the 
PM2.5 standards. Particularly relevant are the Indale and 
Burr studies cited in C. of this section. The Indale study showed that 
facilities where diesel vehicles idle for prolonged periods, such as 
truck stops or freight terminals, can cause elevated PM2.5 
concentrations in the vicinity of the facility.
    The Burr study showed that individual highway projects can also 
result in significant changes in PM2.5. Specifically, in the 
Burr study, a highway bypass opened which removed traffic from a 
roadway that runs through the affected town. After the bypass opened, 
PM2.5 concentrations decreased in the town near the roadway 
where traffic was removed, thereby documenting the impact that traffic 
had been having on local air quality. Based on this and other 
information in the docket for the final rule, EPA concluded that 
certain projects could cause air quality concerns, and therefore, a 
hot-spot analysis is required for these projects.

E. Responses to Other Comments

    EPA received several comments regarding other issues related to its 
statutory interpretations supporting proposed options. Please note that 
some of these comments were related to both PM2.5 and 
PM10 hot-spot requirements, and for the sake of 
completeness, EPA is including the entire comment and response in 
Section III.
Comment
    EPA noted in its previous proposals that Clean Air Act section 
176(c)(3)(B)(ii) only specifically requires hot-spot analyses for 
projects in CO nonattainment areas, and therefore, EPA has discretion 
to decide if hot-spot analyses are necessary to protect air quality in 
PM2.5 and PM10 nonattainment and maintenance 
areas. EPA received comments concerning this interpretation of the 
Agency's statutory authority during the comment period following the 
November 2003 proposal and invited further comments in the December 
2004 supplemental proposal.
    EPA received several comments on this particular legal argument. 
Four commenters believed that EPA demonstrated in the December 2004 
supplemental proposal that all proposed options complied with Clean Air 
Act requirements and that EPA has discretion in applying PM hot-spot 
requirements. These commenters argued that the Clean Air Act does not 
specifically require PM2.5 or PM10 hot-spot 
requirements for any projects. One of these commenters further 
clarified that EPA has the discretion to specify the form of analyses, 
based on availability of information, feasibility of analysis methods, 
and cost and benefit of performing analyses.
    However, other commenters disagreed with this interpretation, and 
believed that the Clean Air Act does not provide EPA the discretion to 
exempt federally funded or approved projects from project-level 
conformity determinations, including PM2.5 and 
PM10 hot-spot analyses. Rather than being superceded by 
section 176(c)(3)(B)(ii) which establishes a special requirement to 
reduce CO violations, applicable only to CO areas before a SIP is 
approved, these commenters believed that Clean Air Act section 
176(c)(1)(A) and (B) take precedence. Section 176(c)(1)(A) and (B) 
apply for all pollutants for which an area is designated nonattainment 
pursuant to Clean Air Act section 107(d), and ``Conformity to an 
implementation plan'' means that the activity must satisfy these 
statutory requirements ``that such activities will not cause or 
contribute to any new violation of any standard in any area,'' 
``increase the frequency or severity of any existing violation of any 
standard in any area'' or ``delay timely attainment.'' Since EPA does 
not have discretion to waive these statutory requirements, these 
commenters believed that PM2.5 and PM10 hot-spot 
analyses should be required, consistent with the statute, for ``any 
activity'' before it may be approved or funded by a Federal agency.
Response
    EPA agrees that the Clean Air Act sets the legal standard for what 
projects have to meet before receiving Federal funding or approval 
(i.e., that they cannot create or worsen violations of any standard or 
delay attainment). EPA also agrees that Clean Air Act 176(c)(1)(A) and 
(B) set this standard, rather than 176(c)(3)(B)(ii). However, EPA also 
believes it has discretion to not require analyses of localized impacts 
of projects if we have scientific evidence that PM2.5 and 
PM10 hot-spots are not a concern with respect to the 
standards. That is, even under the statutory standards of section 
176(c)(1)(A) and (B), if EPA determines through rulemaking that certain 
types of projects will not cause or contribute to violations of any 
standard or delay attainment, EPA concludes that we have the authority 
to determine through the conformity rule that no additional analysis 
would be necessary to meet section 176(c)(1)(A) and (B). Since section 
176(c)(3)(B)(ii) does not affirmatively require emissions reductions in 
PM2.5 or PM10 areas, EPA believes that conformity 
determinations would satisfy section 176(c)(1)(A) and (B) without a 
hot-spot analysis if EPA has demonstrated that specific types of 
projects will not adversely affect air quality standards. EPA certainly 
did not mean to imply in its proposals that we could arbitrarily 
disregard consideration of PM2.5 and PM10 
localized emissions impacts even if such impacts could impact the air 
quality standards.
    EPA agrees that we do not have authority to waive the requirements 
of Clean Air Act section 176(c)(1)(A) and (B), rather we conclude that 
those requirements can be met in certain circumstances without 
additional hot-spot analyses. Nevertheless, since we have information 
that PM2.5 and PM10 hot-spots are a concern for 
certain projects, we are interpreting the statute to apply a specific 
hot-spot requirement to those projects of air quality concern.
Comment
    Other commenters believed that EPA should revise Sec.  93.116(a) of 
the conformity rule so that proposed transportation projects can meet 
all Clean Air Act conformity requirements. These commenters argued that 
EPA had not reflected in the proposed regulatory text all of the 
requirements of Clean Air Act section 176(c)(1)(A) and (B)(i)(iii) that 
transportation activities must contribute to reducing violations and 
providing for expeditious attainment. According to commenters, the 
Clean Air Act establishes an affirmative responsibility on 
transportation projects to help attain the standards, and as a result, 
the conformity rule should be clarified to prohibit conformity 
determinations for projects that cause or contribute to new or 
increased violations after a statutory attainment deadline, or that 
fail to eliminate transportation-related violations by an attainment 
date.
    The commenters provided an example to illustrate their comments. In 
this example, a CO hot-spot analysis determined that the number of 
current CO violations would be eliminated by 2015, but that continued 
growth in vehicle miles traveled (VMT) thereafter would cause at least 
one new violation by 2020. The concentration for the violating receptor 
represented a decrease in the concentration predicted at the same 
receptor under the no-build scenario. In the commenters' opinion, the 
fact that the violation would be less than current violations, or less 
than would be expected under the no-build scenario, is not enough to 
meet statutory

[[Page 12482]]

requirements after an area has attained, or after the attainment date.
Response
    EPA disagrees with commenters and believes that Sec.  93.116(a) of 
the conformity rule meets all statutory requirements. Section 
176(c)(1)(A) requires ``conformity to an implementation plan's purpose 
of eliminating or reducing the severity and number of violations of the 
national ambient air quality standards and achieving expeditious 
attainment of such standards.'' In general, EPA believes that this 
statutory criterion is met if a transportation project is consistent 
with the emissions projections and control measures in the SIP.
    The SIP process is the venue where state and local agencies decide 
on SIP control strategies for attaining the PM2.5 and 
PM10 standards. Section 93.116(a) of the conformity rule 
allows all projects in PM2.5 and PM10 areas to 
meet section 176(c)(1)(A) because it requires all non-exempt projects 
to demonstrate that ``no new local violations will be created and the 
severity or number of existing violations will not be increased as a 
result of the project.'' This is accomplished by requiring 
PM2.5 and PM10 hot-spot analyses for projects of 
air quality concern, with the presumption that all other projects meet 
this requirement.
    EPA has previously addressed a similar type of comment regarding 
the applicability of section 176(c)(1)(A) and commenters' belief that 
this provision requires transportation activities to specifically 
contribute emissions reductions towards attainment. Although it is true 
that transportation projects need to be consistent with a SIP's purpose 
of reducing violations, this can be accomplished by simply not 
increasing violations; EPA concludes that the statute does not require 
an individual transportation project to reduce emissions by itself. 
Individual transportation projects are not required to reduce all 
transportation-related emissions; they need only prevent worsening air 
quality concentrations. So long as the air quality standards are not 
impacted by a new project, the project will meet all applicable 
statutory requirements by not causing or contributing to new 
violations, not increasing the severity of existing violations, not 
interfering with timely attainment and interim progress, and being 
consistent with the overall purpose of the SIP to eliminate all 
violations.
    In the July 1, 2004 final rule, EPA disagreed with this similar 
comment (69 FR 40031). Clean Air Act section 176(c)(3)(A)(iii) is the 
only provision that requires emissions reductions for transportation 
plans and TIPs in higher classifications of ozone and CO nonattainment 
areas prior to having an adequate or approved SIP. This provision does 
not apply in the case of PM2.5 and PM10 
nonattainment and maintenance areas. EPA has already successfully 
defended this legal interpretation in EDF v. EPA, 82 F.3d 451 (DC Cir. 
1996).
    Furthermore, commenters are incorrect in interpreting section 
176(c)(1)(B)(i) and (iii) as prohibiting project approvals in cases 
where new violations are predicted for a year beyond an attainment year 
and a project's implementation is resulting in lower PM2.5 
and PM10 concentrations. The commenters indicated that in 
this context, ``any new violation'' should be construed to apply to a 
violation that is anticipated in the period after the area attains the 
standards.
    Sections 176(c)(1)(A) and (B) should not be interpreted that ``any 
new violation'' should be construed to imply that an individual 
transportation project must remedy any violation that is projected to 
occur after the attainment date as a result of any emissions sources. 
On the contrary, these provisions only require air quality to not be 
worsened by an individual project than what would have otherwise 
occurred. Where the project itself is improving air quality 
concentrations and thus violations from what they would have been 
without the project, EPA concludes that the project is consistent with 
the SIP and meets the applicable conformity requirements.
    As a result, EPA believes that conformity in the example offered by 
the commenter meets statutory requirements. If the project's 
implementation resulted in lower future concentrations than would have 
otherwise occurred without the project, then statutory conformity 
requirements are met. In fact, such a situation would result in more 
than what is required under the statute, since such a project has 
actually reduced future violations from what they would have been 
absent the project.
Comment
    Two commenters believed that transportation plans and TIPs cannot 
be found to conform if they include projects that do not meet Clean Air 
Act requirements. The commenters stated that the conformity rule does 
not explain how MPOs will implement the Clean Air Act requirement to 
not ``approv[e] any project, program or plan which does not conform.'' 
The commenters believed that if projects are found not to conform after 
the TIP has been approved, there should be a requirement to reconsider 
the TIP so that there is an opportunity to revisit the regional 
allocation of available resources. If this opportunity is not provided, 
commenters were concerned that resources may not be available to remedy 
or mitigate the impacts of a particular project's conformity 
determination.
Response
    EPA believes that MPOs and project sponsors are already fulfilling 
the Clean Air Act requirement to not ``approv[e] any project, program 
or plan which does not conform.'' Furthermore, existing transportation 
planning and conformity requirements already provide the opportunity to 
reconsider the allocation of resources in the event that a project 
cannot meet project-level conformity requirements.
    Section 93.122(a)(1) of the conformity rule requires that regional 
emissions analyses, which serve as the basis for determining whether or 
not an area conforms to an approved or adequate SIP motor vehicle 
emissions budget or passes an interim emissions test before budgets are 
available, include all regionally significant projects expected in the 
nonattainment or maintenance area and account for the VMT from non-
regionally significant projects that are not explicitly modeled. 
Clearly, not all of the expected projects planned for an area would 
have received a project-level conformity determination prior to the 
time that they are included in the regional emissions analysis for a 
nonattainment or maintenance area because project-level determinations 
are not made until a project completes the required National 
Environmental Policy Act (NEPA) process.
    If during the NEPA process a project initially does not meet 
project-level hot-spot requirements, there would be two possible 
outcomes. In most cases the project sponsor would attempt to mitigate 
project emissions that are affecting concentrations either through 
changes in the project's design or through implementation of other 
measures that reduce concentrations within the geographic area impacted 
by the project. If a project sponsor was not able to mitigate the 
impacts of such project, the project could not move forward because a 
project-level conformity determination could not be made. Since 
transportation plans and TIPs are updated on a regular basis, the MPO 
would be able to reallocate the

[[Page 12483]]

funding from the project to other projects at that time.
Comment
    One commenter recommended that EPA not finalize any 
PM2.5 or PM10 hot-spot requirements because doing 
so would be contrary to what Congress originally intended. This 
commenter argued that Congress enacted the 1990 Clean Air Act 
Amendments to focus on the emissions impacts of long-range 
transportation plans and TIPs. The commenter stated that the key 
conformity test is whether emissions from the long-range transportation 
plan or TIP, in their entirety, stay within the SIP's motor vehicle 
emissions budget, and the impact of any single project on plan/TIP 
area-wide emissions could be minimal. Meeting the SIP's budget and 
attaining the air quality standards on a county and regional level, the 
commenter argued, is the primary mechanism for an area reaching 
attainment, rather than a momentary increase in the standards at a 
specific project's location. The commenter believed that projects can 
be found to conform without PM hot-spot analyses as long as such 
projects are part of a conforming plan and TIP. The risk of possible 
legal challenges and delays in streamlining project development would 
not be a productive use of resources, the commenter also argued.
Response
    EPA disagrees with these comments. Clean Air Act section 176(c)(2) 
does require that in order for a project to be found to conform it must 
come from a conforming plan and TIP and/or its emissions must have been 
included in the current conformity determination. However, this is not 
the sole statutory requirement that must be satisfied in order for a 
project-level conformity determination to be made. Transportation 
projects must also satisfy the requirements of section 176(c)(1)(B). 
Section 176(c)(1) is written very broadly to apply to any Federal 
activity, and specifically applies to any project as well as any 
transportation plan or TIP.
    Specifically, projects can only be found to conform if it can be 
shown that they do not cause or contribute to new violations, increase 
the frequency or severity of existing violations, or delay timely 
attainment of the relevant air quality standard. EPA has determined 
that certain types of transportation projects may result in localized 
PM2.5 violations. Therefore, in order to satisfy the 
requirements of Clean Air Act section 176(c)(1)(B), a hot-spot analysis 
is required for such projects in order to ensure that new violations 
are not created, existing violations are not worsened, and timely 
attainment is not delayed. A regional emissions analysis for an area's 
entire planned transportation system is not sufficient to ensure that 
individual projects meet the requirements of section 176(c)(1)(B) where 
projects could have a localized air quality impact.
    EPA agrees that regional emissions analyses are critical for 
ensuring that emissions from an area's planned transportation system 
are consistent with emissions estimates contained in the area's SIP, so 
that the area may meet relevant regional air quality goals such as 
attainment or reasonable further progress. However, based on a complete 
reading of Clean Air Act section 176(c), it is clear that Congress 
intended transportation conformity to apply to transportation projects 
as well as plans and TIPs. Thus, hot-spot analyses are required as well 
where localized impacts could occur.
    Finally, the commenter states that the risk of possible legal 
challenges and delays in streamlining project development would not be 
a productive use of resources. But EPA cannot ignore Clean Air Act 
conformity requirements simply because there is a risk that some 
projects may be delayed due to potential lawsuits. Clean Air Act 
section 176(c)(1)(B) clearly requires that it must be shown that 
individual projects do not adversely impact air quality. In this final 
rule, EPA addresses both the Clean Air Act's requirements for project-
level conformity determinations and concerns over limited resources. To 
that end, the final rule requires hot-spot analyses for only those 
projects that have the likelihood of adversely impacting air quality 
rather than requiring an analysis for each non-exempt project, 
including those that EPA concludes would not represent an air quality 
concern.
Comment
    A few commenters urged EPA to consider information that they had 
previously submitted on the costs of performing conformity analyses for 
the new standards in response to EPA's proposed November 25, 2003, 
Information Collection Request (ICR) and final January 5, 2004, ICR (69 
FR 336).
Response
    EPA believes that conformity procedures must first meet the Clean 
Air Act requirements contained in section 176(c) and that these 
procedures should be sensitive to the resource constraints of 
conformity implementers. EPA recognizes that both air quality agencies 
and metropolitan planning organizations are currently involved in 8-
hour ozone and/or PM2.5 SIP development, implementation of 
conformity requirements for these two air quality standards and MPOs 
are currently adapting to changes made by SAFETEA-LU to transportation 
planning and conformity requirements. The final requirements for 
PM2.5 hot-spot analyses meet Clean Air Act conformity 
requirements and minimize the resource burden on state and local 
agencies by focusing these reviews on only those projects that are 
likely to adversely impact air quality rather than requiring analyses 
for every non-exempt project in PM2.5 nonattainment and 
maintenance areas.
    In addition, EPA has already considered the additional burden 
associated with implementing a PM2.5 hot-spot requirement in 
the ICR that has been approved for implementing transportation 
conformity for the 8-hour ozone and PM2.5 standards. EPA has 
already considered and responded to all comments that were made for 
this ICR, which has been approved and assigned OMB control number 2060-
0561. In fact, this ICR actually overestimated the burden associated 
with implementing a PM2.5 hot-spot requirement as compared 
to this final rule's requirements. For example, the ICR assumed that a 
PM2.5 hot-spot analysis would be required for all non-exempt 
federally funded or approved projects in PM2.5 nonattainment 
or maintenance areas, whereas this final rule only requires such 
analyses for projects of air quality concern.

F. When Are the PM2.5 Hot-Spot Requirements Effective?

    Clean Air Act section 176(c)(6) and 40 CFR 93.102(d) provide a one-
year grace period before conformity applies in areas newly designated 
nonattainment for a new standard. On January 5, 2005 (70 FR 943), EPA 
designated areas as attainment and nonattainment for the 
PM2.5 standards. These designations became effective on 
April 5, 2005. As a result, conformity for the PM2.5 
standards will apply to newly designated PM2.5 nonattainment 
areas on April 5, 2006. Starting on that date, PM2.5 hot-
spot requirements for projects of air quality concern as detailed by 
this rulemaking must be met prior to any new Federal approvals for such 
projects.
    Therefore, EPA finds good cause to determine that the final rule is 
effective on April 5, 2006. EPA normally issues final regulations with 
at least a 30-day effective date after Federal Register publication. 
However, state and local implementers are required by the Clean Air Act 
to meet conformity

[[Page 12484]]

requirements in PM2.5 nonattainment areas for transportation 
plans, TIPs, and non-exempt projects as of April 5, 2006, the end of 
the PM2.5 grace period. And since today's final rule 
describes how to meet statutory requirements for projects in 
PM2.5 areas, it is imperative that conformity implementers 
be able to legally use the requirements in this final rule. Absent this 
determination of good cause, EPA would be placing conformity 
implementers in the unfortunate position of waiting until a 30-day 
effective date before conformity rule requirements could be used to 
proceed with any short-term project approvals. For these reasons, EPA 
believes it has good cause to expedite the effective date of this final 
rule in PM2.5 nonattainment areas.

IV. PM10 Hot-Spot Analyses

A. Background and Proposed Options

    EPA proposed to revisit existing PM10 hot-spot 
requirements in parallel with considering new PM2.5 hot-spot 
requirements. As discussed in Section III., EPA originally established 
a PM10 hot-spot requirement in the November 24, 1993 
conformity rule, which required some type of hot-spot analysis--
quantitative or qualitative--for all FHWA and FTA funded or approved 
non-exempt projects in PM10 nonattainment and maintenance 
areas (40 CFR 93.116 and 93.123). These requirements applied for all 
project-level conformity determinations that occurred before and after 
a PM10 SIP is submitted.
    EPA established the PM10 hot-spot requirements so that 
more rigorous quantitative hot-spot analyses would only be required for 
projects that have the potential to impact the PM10 air 
quality standards (i.e., ``projects of air quality concern''), once 
modeling guidance was released. More streamlined, qualitative hot-spot 
analyses were required for all other non-exempt projects, and for all 
non-exempt projects until EPA's modeling guidance was released. All 
hot-spot analyses were intended to demonstrate that a transportation 
project meets Clean Air Act conformity requirements.
    EPA proposed several options to retain, revise, or delete existing 
PM10 hot-spot analysis requirements for project-level 
conformity determinations in PM10 nonattainment and 
maintenance areas. These options were proposed to apply during the time 
periods before and after a PM10 SIP is submitted. EPA is 
repeating the previously proposed options to assist in discussing the 
final rule in today's action.
    To that end, the following options were proposed for 
PM10 hot-spot requirements prior to the submission of a 
PM10 SIP:
     Option 1: Retain the existing conformity rule's 
PM10 hot-spot analysis requirements in all PM10 
areas;
     Option 2: Apply the existing conformity rule's 
PM10 hot-spot analysis requirements, unless the EPA Regional 
Administrator or state air agency finds that localized PM10 
violations are not a concern for a given PM10 area;
     Option 3: Only apply the existing conformity rule's 
PM10 hot-spot analysis requirements, if the EPA Regional 
Administrator or state air agency finds that localized PM10 
violations are a concern for a given PM10 area; or
     Option 4: Delete the current PM10 hot-spot 
analysis requirements from the conformity rule and impose no hot-spot 
analysis requirements.
    EPA acknowledged in the December 2004 supplemental proposal that 
the above proposed options may impact only a small number of 
PM10 areas, since most PM10 areas already have 
submitted or approved PM10 SIPs. EPA also requested 
information from commenters about whether sufficient local information 
was available to make findings under Options 2 and 3.
    EPA proposed three PM10 hot-spot options for project-
level conformity determinations that occur after PM10 SIP 
submission:
     Option A: Retain the existing conformity rule's 
PM10 hot-spot analysis requirements for FHWA/FTA non-exempt 
projects in all PM10 areas with one minor addition, as 
described below;
     Option B: Only require quantitative PM10 hot-
spot analyses for projects at those types of locations that the 
PM10 SIP for a given area identifies as a localized 
PM10 air quality concern. No quantitative or qualitative 
analyses would be required for projects in other types of locations, or 
in PM10 areas where the SIP does not identify types of 
locations as a localized PM10 air quality concern; or
     Option C: Do not apply any PM10 hot-spot 
analysis requirements for any PM10 area and delete the 
current PM10 requirements from the conformity rule.
    Under Option A, EPA proposed to add a new criterion that would 
require that quantitative analyses also be performed at those types of 
project locations that the PM10 SIP identifies as a 
PM10 hot-spot concern. Neither Option B nor C would require 
some type of hot-spot analysis for all projects in the PM10 
nonattainment or maintenance area, as had been required under the 
previous conformity rule's PM10 hot-spot requirements. In 
addition, EPA noted in the December 2004 supplemental proposal that the 
majority of PM10 areas already had an attainment 
demonstration or a maintenance plan in place; therefore, SIP revisions 
may be necessary under Option B to identify types of locations where 
quantitative analyses must be performed.
    For all relevant options, EPA proposed to rely on the existing 
conformity rule provision in Sec.  93.123(b)(4) that does not require 
any quantitative PM10 hot-spot analyses until EPA releases 
quantitative modeling guidance and announces in the Federal Register 
that quantitative modeling requirements are in effect. EPA also 
proposed to retain the existing conformity rule's flexibility in Sec.  
93.123(b)(3) for FTA to make categorical hot-spot findings to 
streamline PM10 hot-spot analyses as appropriate.
    EPA requested comments on all of the proposed options, and invited 
commenters to submit any relevant data or other information, including 
whether state and local agencies would have information available to 
implement the proposed options. The December 2004 supplemental proposal 
included proposed regulatory text that combined various 
PM2.5 and PM10 hot-spot options as illustrative 
examples, and EPA noted that any combination of the proposed 
PM2.5 or PM10 hot-spot options could be 
finalized. See the November 2003 proposal (68 FR 62713-62714) and 
December 2004 supplemental proposal (69 FR 72149-72153) for more 
information on the proposed options.

B. Description of Final Rule

    Consistent with PM2.5 hot-spot requirements, EPA is 
finalizing a hybrid approach that retains aspects of the previous 
PM10 hot-spot requirements while providing flexibility. The 
final rule requires quantitative PM10 hot-spot analyses only 
for projects of air quality concern, and qualitative hot-spot analyses 
would be done for these projects before EPA releases its future 
modeling guidance and announces that quantitative PM10 hot-
spot analyses are required under Sec.  93.123(b)(4). EPA specifies in 
Sec.  93.123(b)(1) that projects of air quality concern are highway and 
transit projects that involve significant levels of diesel vehicle 
traffic, and any other project that is identified in the 
PM10 SIP as a localized concern.
    Today's final rule does not require any hot-spot analysis--
qualitative or quantitative--for all other projects that are not listed 
in Sec.  93.123(b)(1) as an air quality concern. These projects are 
presumed to meet Clean Air Act requirements and 40 CFR 93.116

[[Page 12485]]

without any explicit hot-spot analysis, because EPA concludes based 
upon the available evidence that such projects would not have an impact 
on local air quality. State and local project sponsors should briefly 
document in their conformity documentation for such projects that an 
explicit PM10 hot-spot analysis was not completed because 
Clean Air Act and 40 CFR 93.116 requirements were met without an 
explicit PM10 hot-spot analysis.
    This final rule requires PM10 hot-spot analyses for 
projects of air quality concern in PM10 nonattainment and 
maintenance areas at all times--both before and after a PM10 
SIP is submitted. These projects are anticipated to have the potential 
to increase local PM10 concentrations, and as a result, 
PM10 hot-spot analyses are needed to ensure that the local 
air quality impacts of such projects are considered prior to receiving 
federal funding or approval. Rather than finalize the proposed and 
previous rule's criteria for PM10 analyses, EPA is 
finalizing more specific criteria about the types of projects that 
require such analyses based on our November 2003 and December 2004 
proposals and comments received. See Section V. of this notice for 
further details regarding the regulatory criteria for projects of air 
quality concern and more information on the general requirements for 
performing hot-spot analyses. See Section IX. of today's action for 
further information regarding when today's change in PM10 
requirements would apply in PM10 areas with and without 
approved conformity SIPs.
    In addition, the final rule does not substantively change the 
existing conformity rule flexibility that allows DOT, in consultation 
with EPA, to make categorical hot-spot findings that would further 
streamline quantitative hot-spot analysis requirements in appropriate 
cases, as described further in Section VII.
    This final rule also makes no change in how qualitative 
PM10 hot-spot analyses are currently performed for projects 
of air quality concern, since the previous conformity rule has always 
required a qualitative PM10 hot-spot analysis for all non-
exempt projects in PM10 nonattainment and maintenance areas 
(under the previous rule's Sec.  93.123(b)(2)). As stated in Section 
III., quantitative PM10 hot-spot analyses are not required 
for projects of air quality concern at this time since EPA has not yet 
required quantitative PM10 hot-spot analyses under Sec.  
93.123(b)(4). Qualitative PM10 hot-spot analyses should be 
completed according to joint EPA and DOT guidance, which will be posted 
on the Web site provided in Section I.B.2. of today's notice. Until 
this new guidance is available, FHWA's existing September 12, 2001 
guidance, ``Guidance for Qualitative Project-Level `Hot-Spot' Analysis 
in PM10 Nonattainment and Maintenance Areas,'' can be used. 
See Section VI. of this final rule for more information regarding the 
timing of EPA's future quantitative hot-spot modeling guidance and 
application of quantitative requirements.
    Finally, EPA notes that its future quantitative modeling guidance 
will address how the current 24-hour and annual PM10 air 
quality standards are to be considered in quantitative hot-spot 
analyses. This future guidance will be consistent with how potential 
impacts on the PM10 standards have historically been 
considered for SIP planning, monitoring, and other applicable 
requirements.

C. Rationale

    EPA considered the following factors in developing the final rule's 
PM10 hot-spot requirements:
     The Clean Air Act conformity requirements for individual 
transportation projects in PM10 areas;
     The current scientific understanding of PM10 
hot-spots and public health effects;
     The feasibility of implementing proposed options; and
     The impact of proposed options on state and local 
resources.
    EPA stated in its proposals that it was important to re-evaluate 
the need for hot-spot analyses for PM10 nonattainment and 
maintenance areas, in conjunction with similar options considered for 
PM2.5 hot-spot requirements. The following paragraphs 
outline how EPA considered the above factors in the final rule.
    When the conformity rule was promulgated in 1993, EPA interpreted 
Clean Air Act section 176(c)(1)(B) to require PM10 hot-spot 
analyses because of the requirement to ensure that transportation 
activities do not create new violations, worsen existing violations or 
delay timely attainment of the air quality standard (January 11, 1993, 
58 FR 3776-3777). EPA continues to believe that this statutory 
provision is the applicable standard that applies for considering a 
final PM10 hot-spot requirement, and that the final rule 
meets this legal standard.
    Furthermore, the Clean Air Act requires that section 176(c)(1)(B) 
be met for all FHWA or FTA funded or approved projects, except for 
traffic signal synchronization projects; it does not distinguish that 
these requirements apply based on whether or not a SIP has been 
submitted. Through previous rulemaking, EPA has determined that the 
exempt projects listed in 40 CFR 93.126 have met section 176(c)(1)(B) 
without further hot-spot analyses. Through today's action, EPA is 
determining that projects not identified in the rule as projects of air 
quality concern have also met section 176(c)(1)(B) without further hot-
spot analyses. The final rule requires that all projects of air quality 
concern be analyzed for localized impacts, regardless of whether or not 
the PM10 SIP is submitted.
    As indicated in Section III. of today's notice and above, EPA 
believes that Clean Air Act section 176(c)(1)(B) is the primary legal 
standard that applies for this final rule. This statutory provision 
requires that federally funded and approved projects not create or 
worsen air quality violations or delay timely attainment. Also, since 
projects of air quality concern have the potential to impact local 
PM10 air quality, then a PM10 hot-spot 
requirement is warranted for such projects in today's final rule at all 
times.
    EPA also continues to believe it has discretion to establish the 
level of PM10 hot-spot analysis that is necessary to meet 
statutory requirements. Therefore, EPA is retaining its previous rule's 
approach for requiring quantitative PM10 hot-spot analyses 
only for projects of air quality concern once EPA's modeling guidance 
is available. EPA is revising some of the existing rule's criteria for 
when PM10 analyses are required based on scientific 
information currently available on PM10 hot-spots, and the 
Agency's experience in implementing CO and PM10 hot-spot 
requirements since 1993 for what level of analysis is appropriate and 
worthwhile. The final rule's criteria for what projects require hot-
spot analyses will ensure that all projects that have the potential to 
impact the air quality standards will be analyzed before they receive 
Federal funding or approval. EPA revised its proposed and previous 
rule's criteria for what projects of air quality concern require 
PM10 analyses based on existing scientific information and 
comments received, as discussed further in this section and in Section 
V.
    Furthermore, as stated in Section III., EPA is changing its 
precedent to date in no longer requiring qualitative hot-spot analyses 
for projects that are not of localized air quality concern. As stated 
previously, since the original 1993 conformity rule, some type of hot-
spot analysis has been required to meet statutory requirements for all 
non-exempt FHWA and FTA projects in

[[Page 12486]]

PM10 nonattainment and maintenance areas. However, based on 
the history of implementation of this provision to date, EPA now 
believes that these projects do not represent a localized air quality 
concern and can be presumed to meet Clean Air Act requirements and 40 
CFR 93.116 without any explicit hot-spot analysis because EPA concludes 
based on available data and experience that these projects will not 
have an impact on local air quality.
    The Agency now believes that requiring qualitative hot-spot 
analyses for projects that are not a concern is also not a beneficial 
use of Federal, state, or local resources. This conclusion is based in 
part on a recent review by EPA and DOT field offices of project-level 
conformity determinations involving historical qualitative hot-spot 
analyses in PM10 areas. See Section III.C. for further 
information on EPA and DOT's review of PM10 qualitative hot-
spot analyses and why EPA concludes that they are no longer necessary 
to meet statutory requirements for projects that are not an air quality 
concern.
    However, EPA continues to believe that projects of air quality 
concern have the potential to impact PM10 air quality 
standards and thus require explicit hot-spot analyses to determine if 
any such impacts will result in specific cases, based on existing 
scientific information and the Agency's historical understanding of 
PM10 hot-spots. As stated in the December 2004 supplemental 
proposal, EPA continues to believe it is appropriate to focus 
conformity resources where air quality issues are significant and thus 
need to be in place to address Clean Air Act requirements.
    In developing this final rule, EPA considered information that was 
available when the original 1993 conformity rule was developed, as well 
as new information that was submitted through the rulemaking process or 
has otherwise become available. For example, in 1993, EPA stated that 
direct PM10 emissions would be capable of causing violations 
in conditions of unusually heavy diesel truck/bus traffic and limited 
dispersion, such as street canyons (January 11, 1993, 58 FR 3780). EPA 
has also acknowledged that the role of re-entrained road dust could be 
a major factor in contributing to potential PM10 hot-spots, 
especially in PM10 areas where road dust is a major 
component of the PM10 motor vehicle emissions inventory.
    EPA also considered in the final rule the impact of our new diesel 
fuel and engine standards (January 18, 2001, 66 FR 5002) for the 
necessity of applying any PM10 hot-spot requirement. Such 
standards are expected to significantly impact the amount of 
particulate emissions that will be emitted by new diesel vehicles, and 
consequently may impact the potential for PM10 
transportation-related hot-spots. We considered the time frame over 
which these vehicle standards would phase in. According to the latest 
Vehicle Inventory and Use Survey from the Census Bureau, in 2002, 
vehicles three years of age and younger constituted only 32.3% of U.S. 
truck fleet. If the same age distribution holds for 2010, only about 
one third of trucks on the road will meet the heavy-duty engine 
emissions standards for 2007 and 2010. In this scenario, most trucks on 
the road will still be capable of producing elevated concentrations. As 
such, EPA's new emission standards do not eliminate the need for 
considering PM10 hot-spots from transportation projects 
involving a significant number of diesel vehicles. However, 
consideration of EPA's diesel fuel and engine standards' impact on 
background air quality will be addressed as part of EPA's future 
quantitative modeling guidance and possibly in modeling used to support 
categorical hot-spot findings as described in Section VII. of today's 
notice.
    As described further below, EPA also considered the feasibility and 
resource implications of implementing the proposed options and the 
final rule's requirements to meet statutory requirements before and 
after PM10 SIP submission.

D. Response to Comments

    EPA received comments from state and local transportation and air 
quality agencies, environmental groups, transportation advocates, and 
the general public with respect to the proposed options for 
PM10 areas. Fewer comments were submitted for 
PM10 options as compared to PM2.5 options, and 
preferences were not as consistent for similar options before and after 
PM10 SIPs are submitted, as compared to preferences for 
PM2.5 options.
Comment
    Several commenters supported finalizing PM10 
requirements that were generally consistent with the previous 
conformity rule's provisions for PM10 areas (i.e., Options 1 
and A) because they believed these options were most protective of 
public health. Commenters also supported these options because they 
would promote consistency with EPA's past legal interpretations 
regarding how federally funded and approved transportation projects 
have historically met Clean Air Act section 176(c)(1)(B) requirements 
in PM10 areas. These commenters believed that existing 
science and experience have shown that transportation projects can 
impact local PM10 air quality, and therefore, previous 
PM10 hot-spot requirements should be retained to meet 
statutory requirements.
    These commenters generally did not support Options 4 and C since 
they required no PM10 hot-spot analyses, and they believed 
that these options were inconsistent with current scientific evidence 
regarding the existence of PM10 hot-spots. A few commenters 
indicated that these options also do not provide the same health 
protections as other options. Similarly, another commenter stated that 
it was not in the public's best interest to eliminate all analyses of 
potential PM10 hot-spots, especially due to the commenter's 
experience with respect to the 24-hour PM10 standard. 
Another commenter argued that hot-spot requirements should not be 
deleted because of the known relationship between PM10 
nonattainment areas and transportation-related sources.
    Some of these commenters acknowledged that in practice, proposed 
options prior to a PM10 SIP's submission would not impact 
most areas, but believed if any projects are approved for areas that 
have yet to submit a PM10 SIP, those projects can only meet 
statutory conformity requirements through a PM10 hot-spot 
analysis. One commenter believed that PM10 areas that still 
do not have SIPs need to complete PM10 hot-spot analyses 
because these SIPs are not reliable in protecting the public health of 
their citizens. Another commenter argued that consistency with existing 
PM10 hot-spot requirements and procedures for conformity 
provides better support during environmental reviews from a NEPA and/or 
state environmental process perspective when determining local or 
project-level impacts.
    Still other commenters supported options that would apply no 
PM10 hot-spot requirements (i.e., Options 4 and C), and some 
even preferred that EPA delay issuing a final rule until certain issues 
are addressed. Some of these commenters believed that there was 
insufficient evidence regarding the existence of PM10 hot-
spots. Some commenters also argued that PM10 hot-spot 
requirements are not required by the Clean Air Act, and therefore, an 
option that required PM10 hot-spot analyses should never be 
finalized.
    These commenters were also opposed to requiring existing 
PM10 hot-spot requirements (under Options 1 and A) because 
they believed these options

[[Page 12487]]

would require extensive analyses without comparable environmental 
benefits and flexibility. These commenters believed it was unnecessary 
to require hot-spot analyses for every project in every PM10 
area.
    One of these commenters stated that they had never identified a 
transportation project that had a negative impact on PM10 
concentrations. This commenter noted that transportation projects 
usually reduce PM10 emissions because most projects involve 
paving unpaved roads and/or shoulders or adding curbs or gutters. The 
commenter noted that in most mountainous western states, 
transportation-related PM10 problems result from highway 
maintenance combined with winter air inversions rather than highway 
improvement projects. This commenter stated that these problems are 
addressed in the SIP through requirements for street sweeping, flushing 
and use of chemical de-icers, all of which reduce road dust. Finally 
the commenter indicated that eliminating PM10 hot-spot 
requirements is preferable because state and local agencies can then 
focus their limited resources on other transportation and air quality 
efforts.
Response
    As described above, EPA believes that today's final rule is the 
appropriate way for projects of air quality concern to meet Clean Air 
Act section 176(c)(1)(B) requirements in all PM10 
nonattainment and maintenance areas. EPA agrees that applying a hot-
spot requirement prior to a PM10 SIP being submitted is 
essential for meeting statutory requirements. EPA agrees that today's 
final rule is consistent with its past legal interpretations for 
applying hot-spot requirements for all projects of air quality concern.
    EPA disagrees with commenters who argued that there is insufficient 
information or limited value in applying a PM10 hot-spot 
requirement. Although some commenters noted limited value in performing 
qualitative PM10 hot-spot analyses to date, EPA believes 
that this information further supports its decision to eliminate 
qualitative PM10 hot-spot analyses for projects that are not 
an air quality concern, rather than eliminate all PM10 hot-
spot requirements.
    Based on our review of scientific studies and information gathered 
during the rulemaking process, as described above, EPA believes that 
projects of air quality concern have the potential to impact 
PM10 concentrations, and as a result, the PM10 
standards. Such impacts on communities surrounding a project would be 
contrary to the Clean Air Act's conformity requirements. Thus, EPA 
concludes that hot-spot analyses are necessary for projects of air 
quality concern. Furthermore, EPA does not agree that it is appropriate 
to delay finalizing a change to the PM10 hot-spot 
requirements, for the reasons cited above. EPA has addressed state and 
local resource concerns by eliminating PM10 qualitative hot-
spot analyses for projects that are not an air quality concern.
Comment
    EPA also proposed Option B that relied solely on the SIP to 
identify projects or project locations of potential PM10 
hot-spot concern. Under this option, quantitative PM10 hot-
spot analyses would only be required at types of project locations 
identified as a localized air quality concern in a given 
PM10 SIP. No quantitative or qualitative analyses would be 
required for projects in other types of locations, or in 
PM10 areas where the current or future SIP does not identify 
types of locations as a localized PM10 air quality concern. 
Furthermore, no hot-spot analyses would be completed for any projects 
prior to PM10 SIP submission, for the limited number of 
PM10 areas without SIPs.
    Several commenters supported Option B because they believed that 
the SIP process could assist in identifying what projects are of 
concern in a given area and what level of PM10 hot-spot 
analysis is appropriate. Commenters believed that Option B would allow 
each PM10 area to target potential PM10 hot-
spots, protect public health, and provide necessary flexibility. A few 
other commenters indicated support for Option B because they did not 
agree that there was evidence that transportation projects are a 
PM10 hot-spot concern. Two other commenters even believed 
that this option should apply only once a SIP is approved, rather than 
when a SIP is submitted, unless EPA were establishing a process similar 
to its adequacy process for submitted SIPs with motor vehicle emissions 
budgets that involves sufficient notice and public review.
    Other commenters opposed Option B because they believed it was not 
feasible, and therefore, would not meet statutory requirements or 
protect public health. Commenters noted that most PM10 areas 
already have SIPs that were developed before EPA's proposed options, 
without consideration for implementing a conformity hot-spot 
requirement. If finalized, the commenters believed that Option B would 
result in new projects in most PM10 areas not meeting 
statutory requirements, since no hot-spot requirement would exist 
(because no current PM10 SIPs were designed to implement 
such a requirement).
    Some commenters believed that Option B is also flawed because a 
state has no obligation under the Clean Air Act or conformity 
regulations to identify project locations of air quality concern in its 
SIP. Commenters argued that if states decline to designate such areas 
in their SIPs--whether from the lack of meaningful evidence of problems 
or out of a desire to avoid the application of conformity 
requirements--statutory requirements would not be met. If such a case 
occurred, this commenter was concerned that there would be no legal 
mechanism to challenge a SIP or enforce statutory conformity 
requirements.
    A commenter who did not support Option B as proposed suggested a 
hybrid option where PM10 areas could rely on Option B if the 
SIP addressed the potential for transportation-related hot-spots, but 
if this was not the case, the existing PM10 requirements 
under Option A would apply.
    Some commenters also provided information and thoughts on 
developing PM10 SIPs to implement Option B. One commenter 
believed that revising existing SIPs to address transportation-related 
PM10 hot-spots would allow state and local agencies to focus 
their resources on meaningful analyses. Some commenters believed that 
available local information and resources to develop SIPs to specify 
project locations of concern will vary among PM10 areas. 
Still another commenter was concerned that Option B could be 
problematic if project locations are not identified during SIP 
development, but are subsequently determined through the consultation 
process to have a hot-spot concern. Other commenters believed that the 
consultation process could be used to identify new projects of concern, 
rather than revise existing SIPs.
    Finally, a few commenters went on to state that EPA's proposed 
options that allow states to determine which projects would require 
hot-spot analyses conflict with a previous court decision. However, the 
commenters did not elaborate on what court decision was involved, or 
how Option B contradicted this judicial decision.
Response
    EPA is not finalizing Option B because this option will not ensure 
that all federally funded and approved transportation projects in 
PM10 areas are consistent with Clean Air Act section 
176(c)(1)(B). As described by

[[Page 12488]]

commenters, most PM10 areas already have SIPs that were 
established prior to EPA's proposed conformity options, and therefore, 
were not designed to implement Option B. Due to limited resources, it 
is doubtful that areas will revise SIPs solely to address 
PM10 hot-spots, and even so, it is unclear whether SIPs 
could be developed with sufficient detail to consider the local impacts 
of current and future projects. Based on all of these considerations 
and the comments received, EPA does not believe that it is realistic or 
practical to expect that Option B can be sufficiently implemented to 
meet statutory requirements in all PM10 areas. Further 
discussion on a similar option for PM2.5 hot-spot analyses 
can be found in Section III. of today's action.
Comment
    A few commenters supported Options 2 or 3 which would apply 
existing PM10 hot-spot requirements depending on whether or 
not new or worsened local PM10 violations could occur in a 
given area prior to PM10 SIP submission. For example, one 
commenter believed Option 3--which would require PM10 hot-
spot analyses if EPA or the state air agency found there to be a hot-
spot concern in a given area--would provide the ability to require 
analyses for certain projects. This commenter highlighted his area's 
experience that two types of projects listed in 40 CFR 93.126 (i.e., 
weight inspection stations and bus terminals) may be a PM10 
hot-spot concern due to a high concentration of diesel vehicles.
Response
    EPA is not finalizing approaches such as Options 2 or 3 because it 
is unclear if they can be implemented in a manner that meets statutory 
requirements. See Section III. of today's action for further rationale 
regarding why such options are not being finalized. However, today's 
final rule provides some of the flexibility intended by these options, 
i.e., targeting PM10 hot-spot analyses for projects that 
have the potential to impact PM10 air quality.
Comment
    A few commenters argued that EPA may not lawfully finalize options 
that defer PM10 hot-spot analyses until after a SIP is 
submitted because such delays are inconsistent with Clean Air Act 
requirements. Commenters believed that Clean Air Act section 176(c)(1) 
does not require that a SIP for a given standard be established before 
conformity requirements for that standard apply. Section 176(c)(1) 
states that Federal and MPO approval actions cannot be done for ``* * * 
any project * * * which does not conform to an implementation plan 
approved or promulgated under section 7410 of this title.''
Response
    EPA agrees that it is not appropriate to defer project-level hot-
spot analyses until PM10 SIPs are developed, and thus has 
not chosen these proposed options in the final rule. See Section III. 
for more on EPA's response to a similar comment raised for 
PM2.5 hot-spot analyses.
Comment
    Some commenters were concerned that finalizing options that 
required PM10 hot-spot analyses for all projects (Options 1 
and A) could result in an inefficient use of state and local resources, 
and therefore, deleting or defining PM10 hot-spot 
requirements through the SIP process was a more appropriate use of 
resources.
    However, as stated above, other commenters believed that having no 
or only limited PM10 hot-spot analyses did not meet 
statutory requirements or protect public health. Furthermore, they 
believed that implementing the previous PM10 hot-spot 
requirements has not been burdensome, so continuing to do this under 
the final rule would be acceptable.
Response
    EPA believes that the final rule will ensure that state and local 
resources are used in an efficient manner, since PM10 hot-
spot analyses will only be required for projects of air quality 
concern. Eliminating qualitative PM10 hot-spot analyses for 
projects that are not an air quality concern will significantly reduce 
any resource challenges in implementing this final rule, since most 
projects should not be considered an air quality concern. As noted 
above, EPA concludes that this does comply with statutory requirements. 
EPA will continue to work with DOT to assist state and local agencies 
in implementing the final rule's requirements.
Comment
    Other commenters were concerned that EPA has yet to issue 
PM10 quantitative hot-spot analysis guidance and methods. 
Some commenters supported doing little or no PM10 hot-spot 
analyses, in part because credible tools are not currently available. 
However, other commenters believed that all of the proposed options 
were insufficient since they would delay quantitative PM10 
hot-spot analyses for years, and in the interim, there would be no 
consideration of the public health impacts of projects currently under 
development.
Response
    Today's final rule retains Sec.  93.123(b)(4) of the existing 
conformity rule that requires quantitative PM10 hot-spot 
analyses once EPA announces in the Federal Register that quantitative 
analysis requirements are in effect. EPA has not yet made such an 
announcement because the Agency believes that appropriate motor vehicle 
emissions factor models are not yet available for localized analyses, 
and EPA is in the initial stages of developing quantitative hot-spot 
modeling guidance to implement today's rule. Please see Section VI. of 
today's final rule for further information on the timing of 
quantitative hot-spot requirements. However, pending development of 
such guidance, the final rule does require qualitative PM10 
hot-spot analyses for all projects of air quality concern, so 
consideration of the public health impacts of proposed projects of air 
quality concern will not be delayed.
Comment
    Some commenters stated that PM10 hot-spot requirements 
should be suspended until (1) it can be demonstrated scientifically 
that re-entrained dust from induced traffic creates PM10 
hot-spots, and (2) there are more reliable techniques to quantify re-
entrained PM10 created by induced traffic on paved roads.
    Another commenter stated that it is reasonable to expect that some 
projects would create localized impacts, especially due to the large 
amounts of re-entrained road dust generated from roadways. This 
commenter believed that EPA should develop criteria and guidance under 
which EPA, state or local air pollution control agencies would have the 
option of requiring project-level PM10 hot-spot analyses. 
Another commenter went on to state that, while re-entrained road dust 
emissions can be a greater contributor to PM10 
concentrations than tailpipe emissions, most projects are done on paved 
roads where re-entrained road dust is less of an issue compared to 
unpaved roads.
Response
    EPA believes based on the available evidence included in the docket 
for this rulemaking that certain transportation projects have the 
potential to impact PM10 air quality standards, and 
therefore, a PM10 hot-spot analysis for these projects is 
needed to meet statutory requirements. Furthermore,

[[Page 12489]]

sufficient scientific information exists to support the final rule's 
requirements, and EPA will consider whether additional information is 
warranted for modeling road dust in its future PM2.5 and 
PM10 quantitative hot-spot modeling guidance.
Comment
    Some commenters believed that EPA could improve on its proposed 
options in the final rule, such as adopting a screening method or 
emissions threshold that would help define what projects require 
quantitative hot-spot analyses.
Response
    EPA believes that today's action addresses this comment by further 
refining what projects are an air quality concern and need 
PM10 hot-spot analyses. See Section V. for further 
information on the criteria for projects of air quality concern 
finalized in today's action. The elimination of qualitative hot-spot 
analyses for projects not of concern in part addresses the motivation 
for a screening method or emissions threshold--e.g., to focus more 
rigorous quantitative analyses on projects of air quality concern.
Comment
    A few commenters argued that applying the previous PM10 
hot-spot requirements was not necessary due to unique circumstances of 
their individual PM10 area. Several commenters stated that 
it is inefficient to direct resources to PM10 hot-spot 
analysis when transportation projects may not be a significant 
contributor to the PM10 problem in a given area, such as 
smaller areas or cities dominated by other PM sources.
    One commenter said there were four PM10 nonattainment 
and maintenance areas in their state where the operation of specific 
industries (e.g., quarries, cement plants, steel fabrication plants) is 
the primary source of direct PM10 emissions. Monitors over 
the last ten years have shown attainment for the PM10 
standards, but the commenter's state had not submitted redesignation 
requests to maintenance for two of the areas due to local concerns for 
specific non-transportation sources. Therefore, this commenter 
supported the option of only requiring PM10 hot-spot 
requirements if a SIP is submitted that identifies transportation 
sources as a significant contributor to the PM10 air quality 
problem.
    Another commenter believed its state needed flexibility to 
consider, through the SIP and consultation processes, the hot-spot 
concerns of its remote communities. The commenter believed the existing 
PM10 hot-spot requirements resulted in a one-size-fits-all 
approach that is not appropriate for its PM10 nonattainment 
and maintenance areas.
Response
    EPA believes that the final rule's PM10 hot-spot 
requirements along with the conformity rule's existing provisions 
concerning areas with insignificant emissions serve to protect air 
quality and public health in PM10 nonattainment and 
maintenance areas. First, today's final hot-spot rule targets 
PM10 hot-spot analyses only for projects that are likely to 
cause or contribute to new or worsened PM10 violations. 
Specifically, the rule targets hot-spot analyses on those types of 
projects that result in significant increases in diesel vehicle traffic 
and emissions, which is likely to be a small subset of projects in many 
areas.
    Second, 40 CFR 93.109(k) already allows PM10 areas with 
insignificant regional motor vehicle emissions to demonstrate, when 
appropriate, that individual projects will not create new localized 
violations or make existing violations worse. Projects in such cases 
would not require PM10 hot-spot analyses. Therefore, areas 
where other types of sources principally contribute to nonattainment 
problems (such as specific stationary sources) would only be required 
to perform PM10 hot-spot analyses for the types of projects 
described in Sec.  93.123(b)(1) until such time as a SIP is submitted 
which demonstrates that regional PM10 on-road emissions are 
insignificant and that projects will not cause new violations or make 
existing violations worse.
    EPA also acknowledges that the practical impact of today's final 
rule may have a minimal impact on the small areas described by 
commenters, since there may not be a large number or any projects of 
air quality concern developed before a PM10 SIP is submitted 
that demonstrates insignificance. After EPA makes an adequacy finding 
on (or approves) such a SIP, PM10 hot-spot analyses would no 
longer be required in that area. EPA Regions and states can work 
together to expedite the processing of such SIPs through such methods 
as parallel processing or direct final rulemaking as appropriate.
    With regard to the concerns expressed about the appropriateness of 
hot-spot analyses in remote or non-urbanized areas, EPA would like to 
point out that today's final rule limits the need for PM10 
hot-spot analyses to only those projects which significantly increase 
diesel vehicle traffic and emissions. As noted in Section III., this is 
likely to be only a small percentage of projects in remote or non-
urbanized areas.
Comment
    A few commenters argued that EPA's standards for low sulfur diesel 
fuels in 2006 and heavy-duty engines in 2007 will negate any need for 
PM10 hot-spot analyses. The commenters stated that EPA 
should analyze the impacts of these federal standards on local air 
quality before the rule is finalized.
Response
    As described in C. of this section, EPA has considered the impacts 
of the new diesel standards, and has determined that PM10 
hot-spot analyses are still warranted for projects of air quality 
concern. However, consideration of EPA's diesel fuel and engine 
standards' impact on background air quality will be addressed as part 
of EPA's future quantitative modeling guidance and possibly in modeling 
used to support categorical hot-spot findings as described in Section 
VII. of today's notice.
Comment
    One commenter expressed support for the previous conformity rule's 
PM10 hot-spot requirements until the current PM10 
standards are replaced by a new PM-coarse air quality standard, because 
current hot-spot requirements protect public health.
Response
    EPA will evaluate the impact of any new air quality standards and 
how they impact the current PM10 transportation conformity 
requirements, including hot-spot requirements, if and when such 
standards are promulgated. However, since the PM10 standards 
and applicable requirements continue to apply at this time, today's 
final rule continues to address the current PM10 standards. 
As explained above, EPA has concluded that requiring hot-spot analyses 
only for projects of air quality concern provides for both compliance 
with statutory requirements and appropriate commitment of resources.

E. Responses to Other Comments

    EPA received several comments on PM2.5 and 
PM10 hot-spot analyses that covered broader legal arguments 
or other topics than the proposed options. Rather than restate all of 
those comments and responses again here, please see Section III.E. for 
further information and response to these comments covering both 
PM2.5 and PM10.

[[Page 12490]]

F. When Are the PM10 Hot-spot Requirements Effective?

    For reasons described in Section III.F., the final rule is 
effective on April 5, 2006. Since the same provisions of the amended 
rule apply in PM10 areas as well as PM2.5 areas, 
EPA finds good cause to have these rules effective on April 5, 2006, 
for PM10 areas as well. EPA believes it would not be in the 
public interest to attempt to draft the regulations to apply to 
different areas on different dates as it would be overly confusing and 
difficult to implement. In addition, this final rule is published 
almost 30 days before April 5, 2006, so PM10 areas should 
not have any difficulty complying with these regulations as of April 5, 
2006. See Section IX. of today's notice for more information on when 
the final rule's PM10 hot-spot provisions will apply in 
PM10 nonattainment and maintenance areas with approved 
conformity SIPs.

V. Projects of Air Quality Concern and General Requirements for 
PM2.5 and PM10 Hot-spot Analyses

A. Background

    This section covers the specific types of projects that are 
required to have PM2.5 and PM10 hot-spot 
analyses. The following paragraphs describe what the conformity rule 
has previously required in PM10 areas as well as what types 
of projects were proposed to receive PM2.5 and 
PM10 hot-spot analyses under the November 2003 and December 
2004 proposals.
    As stated in Sections III. and IV., EPA proposed in the December 
2004 notice a range of options for when quantitative or qualitative 
PM2.5 or PM10 hot-spot analyses would be required 
for the time periods before and after a SIP is submitted. As part of 
some of those options, EPA proposed to require the following projects 
to have PM2.5 and PM10 hot-spot analyses:
     Section 93.123(b)(1)(i): Projects which are located at 
sites at which violations have been verified by monitoring data;
     Section 93.123(b)(1)(ii): Projects which are located at 
sites which have vehicle and roadway emission and dispersion 
characteristics that are essentially identical to those of sites with 
verified violations (including sites near one at which a violation has 
been monitored);
     Section 93.123(b)(1)(iii): New or expanded bus and rail 
terminals and transfer points which significantly increase the number 
of diesel vehicles congregating at a single location; and
     Section 93.123(b)(1)(iv): Projects in or affecting 
locations, areas, or categories of sites which are identified in the 
PM2.5 or PM10 applicable implementation plan or 
implementation plan submission, as appropriate, as sites of violation 
or possible violation.
    These proposed criteria were generally consistent with what the 
conformity rule had required for quantitative hot-spot analyses once 
tools and EPA modeling guidance are released, since the original 1993 
conformity rule in PM10 areas, with a few exceptions.
    First, EPA proposed to clarify that quantitative analyses would be 
required only for new or expanded bus and rail terminals and transfer 
points that significantly increase the number of diesel vehicles 
(rather than any increase of diesel vehicles). Second, EPA proposed to 
add a new criterion--consistent with the current rule's CO quantitative 
hot-spot requirements--to require PM2.5 or PM10 
quantitative hot-spot analyses for those projects that the 
PM2.5 or PM10 SIP identifies as a hot-spot 
concern.
    In addition, in the context of options that would rely on the SIP 
to identify all projects of air quality concern (e.g., Option B), EPA 
provided the following examples of types of projects and locations that 
could be identified in a SIP, and as a result, need PM2.5 or 
PM10 quantitative hot-spot analyses:
     Highly congested intersections,
     Locations of highest traffic volumes,
     Large transit stations or freight terminals where a 
Significant increase in diesel vehicle traffic and engine idling 
occurs,
     Projects involving long or steep grades, or
     Monitors where the PM2.5 or PM10 
standards has been exceeded or violated.
    EPA noted in its proposals that the locations listed above are 
similar to the conformity rule's original requirements in Sec.  
93.123(a)(1)(i)-(iv) and Sec.  93.123(b)(1)(i)-(iii) for projects that 
required quantitative hot-spot analyses in CO and PM10 
areas. EPA requested comment on the above examples and for any other 
information regarding other types of projects and locations where 
potential PM2.5 or PM10 hot-spots could occur in 
a given area. See the November 5, 2003 proposal (68 FR 62712) and 
December 13, 2004 supplemental proposal (69 FR 72144) for further 
background information. EPA also noted that any combination of proposed 
PM2.5 or PM10 hot-spot options could be included 
in the final rule.

B. Projects of Air Quality Concern

1. Description of Final Rule
    This final rule requires PM2.5 and PM10 hot-
spot analyses only for projects that are considered to have the 
potential to impact the air quality standards (i.e., ``projects of air 
quality concern''). Section 93.123(b)(1) of today's final rule requires 
PM2.5 and PM10 hot-spot analyses for the 
following projects of air quality concern:
     Section 93.123(b)(1)(i): New or expanded highway projects 
that have a significant number of or a significant increase in diesel 
vehicles;
     Section 93.123(b)(1)(ii): Projects affecting intersections 
that are at Level-of-Service \7\ D, E, or F with a significant number 
of diesel vehicles, or those that will change to Level-of-Service D, E, 
or F because of increased traffic volumes from a significant number of 
diesel vehicles related to the project;
---------------------------------------------------------------------------

    \7\ Highway Capacity Manual 2000 states on pp. 10-4 through 10-5 
that ``[t]he average travel speed for through vehicles along an 
urban street is the determinant of the operating level of service 
(LOS). The travel speed along a segment, section, or entire length 
of an urban street is dependent on the running speed between 
signalized intersections and the amount of control delay incurred at 
signalized intersections.'' Level-of-service D, E, and F are 
considered the most congested intersections for planning purposes.
---------------------------------------------------------------------------

     Section 93.123(b)(1)(iii): New bus and rail terminals, and 
transfer points, that have a significant number of diesel vehicles 
congregating at a single location;
     Section 93.123(b)(1)(iv): Expanded bus and rail terminals, 
and expanded transfer points, which significantly increase the number 
of diesel vehicles congregating at a single location; and
     Section 93.123(b)(1)(v): Projects in or affecting 
locations, areas, or categories of sites which are identified in the 
PM10 or PM2.5 applicable implementation plan or 
implementation plan submission, as appropriate, as sites of violation 
or possible violation.
    Quantitative hot-spot analyses are required for conformity 
determinations of such projects in PM2.5 and PM10 
areas once EPA provides guidance and announces that such analyses are 
required under Sec.  93.123(b)(4). See Section VI. for more information 
regarding the timing of quantitative hot-spot analyses for projects of 
air quality concern and EPA's future modeling guidance.
    Prior to quantitative analyses being required, section 93.123(b)(2) 
requires qualitative PM2.5 and PM10 hot-spot 
analyses for projects of air quality concern. State and local agencies 
should follow EPA and DOT's guidance document for completing 
qualitative

[[Page 12491]]

PM2.5 and PM10 hot-spot analyses, which will be 
posted on the EPA Web site that is listed in Section I.B.2. of today's 
notice. Until this new guidance is available, FHWA's existing September 
12, 2001 guidance, ``Guidance for Qualitative Project-Level ``Hot-
Spot'' Analysis in PM10 Nonattainment and Maintenance 
Areas,'' can be used for PM10 hot-spot analyses.
2. Examples
    Some examples of projects of air quality concern that would be 
covered by Sec.  93.123(b)(1)(i) and (ii) are:
     A project on a new highway or expressway that serves a 
significant volume of diesel truck traffic, such as facilities with 
greater than 125,000 annual average daily traffic (AADT) and 8% or more 
\8\ of such AADT is diesel truck traffic;
---------------------------------------------------------------------------

    \8\ This percentage is the national average of truck vehicle 
miles traveled (VMT) to total VMT, based on FHWA's Highway 
Statistics publication which can be found at: http://www.fhwa.dot.gov/policy/ohim/hs04/index.htm. EPA's MOBILE6.2 motor 
vehicle emissions model also uses 8% truck VMT as a national 
default.
---------------------------------------------------------------------------

     New exit ramps and other highway facility improvements to 
connect a highway or expressway to a major freight, bus, or intermodal 
terminal;
     Expansion of an existing highway or other facility that 
affects a congested intersection (operated at Level-of-Service D, E, or 
F) that has a significant increase in the number of diesel trucks; and
     Similar highway projects that involve a significant 
increase in the number of diesel transit busses and diesel trucks.
    EPA notes that the above examples are considered to be the most 
likely projects that would require a PM2.5 or 
PM10 hot-spot analysis under today's final rule.
    The following are examples of projects that are not an air quality 
concern under Sec.  93.123(b)(1)(i) and (ii) of this final rule:
     Projects that do not meet the criteria under Sec.  
93.123(b)(1), such as any new or expanded highway project that 
primarily services gasoline vehicle traffic (i.e., does not involve a 
significant number or increase in the number of diesel vehicles), 
including such projects involving congested intersections operating at 
Level-of-Service D, E, or F;
     An intersection channelization project or interchange 
configuration project that involves turn lanes or slots, lanes or 
movements, that are physically separated. These kinds of projects 
improve freeway operations by smoothing traffic flow and vehicle speeds 
by improving weave and merge operations, which would not be expected to 
create or worsen PM2.5 or PM10 violations; and
     Intersection channelization projects, traffic circles or 
roundabouts, intersection signalization projects at individual 
intersections, and interchange reconfiguration projects that are 
designed to improve traffic flow and vehicle speeds, and do not involve 
any increases in idling. Thus, they would be expected to have a neutral 
or positive influence on PM2.5 or PM10 emissions.
    Some examples of projects of air quality concern that would be 
covered by Sec.  93.123(b)(1)(iii) and (iv) are:
     A major new bus or intermodal terminal that is considered 
to be a ``regionally significant project'' under 40 CFR 93.101; \9\ and
---------------------------------------------------------------------------

    \9\ 40 CFR 93.101 defines a ``regionally significant project'' 
as ``a transportation project (other than an exempt project) that is 
on a facility which serves regional transportation needs (such as 
access to and from the area outside of the region, major activity 
centers in the region, major planned developments such as new retail 
malls, sports complexes, etc., or transportation terminals as well 
as most terminals themselves) and would normally be included in the 
modeling of a metropolitan area's transportation network, including 
at a minimum all principal arterial highways and all fixed guideway 
transit facilities that offer an alternative to regional highway 
travel.''
---------------------------------------------------------------------------

     An existing bus or intermodal terminal that has a large 
vehicle fleet where the number of diesel busses increases by 50% or 
more, as measured by bus arrivals.
    Again, the above examples are considered to be the most likely 
projects that would require a PM2.5 or PM10 hot-
spot analysis under today's final rule.
    Examples of projects that are not an air quality concern under 
Sec.  93.123(b)(1)(iii) and (iv) would be:
     A new or expanded bus terminal that is serviced by non-
diesel vehicles (e.g., compressed natural gas or hybrid-electric 
vehicles); and
     A 50% increase in daily arrivals at a small terminal 
(e.g., a facility with 10 buses in the peak hour).
3. Rationale
    Legal rationale for targeting diesel vehicles. EPA continues to 
believe it has discretion to establish the level of PM2.5 
and PM10 hot-spot analysis that is necessary to meet 
statutory requirements. The Clean Air Act requires that projects not 
create new air quality violations, exacerbate existing violations, or 
delay timely attainment, but the statute does not specify what type of 
analysis is needed to meet these requirements. Therefore, EPA is 
finalizing criteria for when hot-spot analyses are required based on 
scientific information available on PM2.5 and 
PM10 hot-spots, and the Agency's experience in implementing 
CO and PM10 hot-spot requirements since 1993 for what level 
of analysis is appropriate and worthwhile. As described in Sections 
III. and IV., the final rule does not require any hot-spot analysis--
qualitative or quantitative--for all other projects that are not listed 
in Sec.  93.123(b)(1) as an air quality concern. These projects are 
presumed to meet Clean Air Act requirements and 40 CFR 93.116 without 
any explicit hot-spot analysis because EPA concludes based on the 
available data that these projects do not have the potential to cause 
or contribute to violations.
    The final rule's criteria for hot-spot analyses targets highway and 
transit projects that involve a significant increase in diesel vehicle 
traffic, since EPA believes that directly emitted particles from diesel 
vehicles are the primary consideration for potential PM2.5 
and PM10 hot-spots. EPA believes the final rule's criteria 
for what projects require hot-spot analyses will ensure that all 
projects that have the potential to impact air quality by causing new 
violations, making existing violations worse or delaying timely 
attainment will be analyzed before they receive federal funding or 
approval. The final criteria are consistent with comments that we 
received, as discussed further below.
    Technical rationale for targeting diesel vehicles. There is 
substantial evidence that sites near concentrated diesel activity can 
experience higher concentrations of PM2.5 and 
PM10 relative to background sites. EPA has considered 
several technical factors in making this conclusion in today's final 
rule.
    First, PM2.5 and PM10 diesel emission factors 
are significantly higher than gasoline vehicles on a per-vehicle basis, 
and direct particulate emissions from gasoline vehicles are more evenly 
distributed across all types of vehicle activity. Current 
PM2.5 and PM10 exhaust emission factors in 
MOBILE6.2 for heavy duty diesel vehicles are approximately 40 to 50 
times the rates for gasoline vehicles, on a per vehicle basis. Even 
with the implementation of tighter heavy duty vehicle emission 
standards beginning in 2007, MOBILE6.2 projects that PM2.5 
and PM10 emission factors for heavy duty diesel vehicles 
will still be 15 to 20 times the rate for gasoline vehicles in 2015. 
Given this difference in emission rates, projects involving increases 
in diesel vehicle activity are much more likely to result in conditions 
associated with a potential air quality concern.

[[Page 12492]]

    Second, several studies examined air quality at sites involving 
high-diesel traffic which showed consistently positive findings; 
whereas, sites with low diesel traffic showed more inconsistent 
results. High levels of vehicle-related particles arise in areas with 
high diesel activity, particularly areas with elevated acceleration or 
in areas with large numbers of trucks operating for long periods in 
close proximity, such as around truck routes, freight terminals or 
truck stops. Studies in proximity of vehicular traffic tend to show 
that elevated PM2.5 concentrations occur near diesel vehicle 
operations, but show less consistent evidence near locations with high 
gasoline vehicle operations.
    For example, one recently-published study (Charron et al., 2005) 
from a site in downtown London, England, conducted a hierarchical 
cluster analysis of PM2.5 concentrations, 
PM2.5-10,\10\ CO, oxides of nitrogen (NOX), 
light-duty traffic, and heavy-duty traffic. Two clusters were found. CO 
clustered with light-duty traffic, in one cluster, while 
PM2.5, PM2.5-10, and NOX clustered 
with heavy-duty traffic in the other. No clusters indicating changes in 
PM2.5 air quality were found for light-duty traffic, which 
further supports EPA's rationale for targeting hot-spot analyses for 
projects involving significant traffic from diesel vehicles. Another 
study (Cyrys et al., 2003) showed that the difference in long-term 
average PM2.5 mass between traffic sites and background 
sites was equal to the difference in elemental carbon mass between the 
two types of sites. Elemental carbon predominantly comes from diesel 
exhaust, as demonstrated in several source apportionment studies. 
Finally, in a Dutch study (Janssen et al., 2001), concentrations of 
PM2.5 measured outside schools were significantly associated 
with truck traffic on nearby motorways and distance from the motorways, 
but not with car traffic.
---------------------------------------------------------------------------

    \10\ PM2.5-10 considers air quality concentrations of 
particles of a diameter of 2.5-10 micrometers.
---------------------------------------------------------------------------

    In addition, studies examining sites with only gasoline vehicle 
traffic show much less consistency in results for whether or not such 
traffic is a PM2.5 or PM10 air quality concern at 
the project level. For example, Kuhn et al. (2005) measured 
PM2.5 concentrations at sites 2.5 meters and about 150 
meters away from a major freeway in Los Angeles that was restricted to 
light-duty vehicle traffic. Traffic volumes during sampling were around 
5700 per hour. Differences in average mass concentrations for 
PM2.5 between upwind and downwind monitors at one site 
ranged from -0.2 [mu]g/m3 for particles with 180-2500 nm 
diameters to 1.8 [mu]g/m3 for smaller particles. At another 
site, total particle mass under 180 nm diameter differed by 3.8 or 4.1 
[mu]g/m3, depending on measurement method. Due to the 
relative inconsistency of PM2.5 results across the study 
area, this study demonstrates that gasoline vehicles do not appear to 
reliably create higher PM2.5 concentrations that could 
create or worsen an air quality violation in a localized area.
    These and other studies provide consistent evidence for elevated 
PM2.5 concentrations associated with nearby diesel vehicle 
activity, while for gasoline vehicle activity, the evidence is less 
consistent. Because diesel vehicle activity tends to be more 
concentrated along truck routes, freight terminals, and truck stops, 
the air quality impact of direct PM2.5 emissions from these 
vehicles is likely to be more geographically focused. Compared to 
diesel vehicles, gasoline vehicles tend to be relatively uniformly 
distributed throughout an urban area.
    In conclusion, EPA believes that it is appropriate to only require 
PM2.5 and PM10 hot-spot analyses for projects 
that involve significant numbers of diesel vehicles, based on current 
information and PM2.5 and PM10 air quality 
standards. EPA will continue to review and evaluate new research on the 
mass and distribution of direct PM2.5 and PM10 
emissions from gasoline and diesel vehicles in the future.
    Rationale for specific criteria for identifying projects of air 
quality concern. EPA has made several revisions to the criteria in 
Sec.  93.123(b)(1) to ensure that PM2.5 and PM10 
hot-spot analyses are completed for all projects of air quality 
concern. Rather than finalize only the proposed criteria for 
PM2.5 and PM10 quantitative analyses, EPA is 
finalizing more specific criteria for the types of projects that 
require evaluation consistent with the discussions in the proposals and 
comments received. The following paragraphs describe in more detail 
EPA's rationale for the specific criteria in this final rule.
    First, EPA is finalizing two criteria to specifically target 
highway projects that involve significant increases in diesel vehicle 
traffic (Sec.  93.123(b)(1)(i) and (ii)), so that highway projects of 
air quality concern are analyzed and therefore meet statutory 
requirements. The final rule requires PM2.5 and 
PM10 analyses for ``new or expanded highway projects that 
have a significant number of or significant increase in diesel 
vehicles,'' and somewhat consistent with a similar criterion for CO 
quantitative hot-spot analyses, ``projects affecting intersections that 
are at Level-of-Service D, E, or F with a significant number of diesel 
vehicles, or those that will change to Level-of Service D, E, or F 
because of increased traffic volumes from a significant number of 
diesel vehicles related to the project.'' \11\
---------------------------------------------------------------------------

    \11\ EPA notes, however, that the CO criterion in 40 CFR 
93.123(a)(1)(ii) focuses on all such intersections. In contrast, 
today's final rule only focuses on such intersections involving 
significant levels of new diesel traffic.
---------------------------------------------------------------------------

    EPA believes that it can finalize these revised criteria for 
highway projects of air quality concern based on information provided 
in preamble discussions, in the proposals, and comments received as 
discussed further below. To omit such highway projects from hot-spot 
analyses would not ensure that these projects meet statutory 
requirements. See Section VII. for how categorical hot-spot findings 
could take into account air quality circumstances for projects of 
concern and ultimately eliminate the need for a quantitative analysis 
for some individual projects.
    Second, EPA is deleting the previous conformity rule's vague 
criteria that would have required quantitative PM2.5 and 
PM10 hot-spot analyses for projects that ``are located at 
sites at which violations have been verified by monitoring'' and 
``which are located at sites which have vehicle and roadway emission 
and dispersion characteristics that are essentially identical to those 
of sites with verified violations (including sites near one at which a 
violation has been monitored).'' EPA also notes that the final rule 
deletes a consultation requirement from Sec.  93.105(c)(1)(v) and Sec.  
93.123(b)(3) of the previous conformity rule, which were intended to 
implement these previous vague criteria. While the air quality 
circumstances at a project's location are an important modeling 
consideration, these previous regulatory criteria are insufficient to 
ensure that all projects of air quality concern are analyzed before 
they receive federal funding or approval. The final rule's criteria 
will ensure that all projects that have the potential to impact a local 
air quality violation will be analyzed. All other projects are not 
expected to impact the air quality standards, even in the case where 
such a project is located near a violating monitor or is similar to a 
project by a violating monitor.
    EPA believes that the critical factor for establishing 
PM2.5 and PM10 hot-spot criteria is whether or 
not a project's direct PM2.5 or PM10 emissions 
could actually cause a new violation or worsen an existing air quality 
violation. The previous criteria did not address

[[Page 12493]]

specific types of projects that have significant levels of diesel 
emissions. Instead, the previous criteria could have resulted in hot-
spot modeling for any project being located near an existing violating 
monitor or for any project that is similar to a project that is near an 
existing violating monitor, even if the project is not anticipated to 
result in enough PM2.5 or PM10 emissions to 
impact local air quality. An example of such a project could be a minor 
arterial that primarily serves gasoline fueled passenger vehicles. As 
discussed above, EPA concludes that quantitative hot-spot modeling for 
such a project is not necessary to meet statutory requirements, and 
would be a waste of limited state and local resources. Further 
discussion on the elimination of these criteria are discussed below in 
the response to comments part of this section.
    Next, EPA is finalizing Sec.  93.123(b)(1)(iii) and (iv) relating 
to bus and rail terminals to be consistent with its December 2004 
supplemental proposal and previous PM10 requirements. EPA 
has split the proposed and previous criterion into two separate 
criteria since the factors to consider for brand new versus expanded 
terminals and transfer points are different. Whereas a new terminal or 
transfer point would look at whether the total number of diesel 
vehicles was significant, an expansion of an existing terminal or 
transfer point would be evaluated based on whether the increase from 
current operations was significant for a given project's circumstances.
    Today's action clarifies Sec.  93.123(b)(1)(iii) and (iv) so that 
quantitative hot-spot analyses would only be required for such projects 
that involve significant increases of diesel vehicle traffic, and not 
insignificant vehicle increases with de minimis localized emissions 
increases. EPA believes that it can finalize these minor clarifications 
to existing PM10 hot-spot requirements and create 
PM2.5 requirements as a logical outgrowth of the December 
2004 proposal and comments received.
    EPA is also finalizing its proposed new criterion for when 
PM2.5 and PM10 hot-spot analyses are completed if 
a PM2.5 or PM10 SIP identifies additional 
projects of air quality concern for a given area. Since the primary 
intent of the Clean Air Act is to ensure consistency between 
transportation decisions and SIP air quality objectives, it is 
appropriate to require more intensive hot-spot analyses in cases where 
the SIP specifically identifies a type of transportation project 
location as having the potential to increase local emissions and worsen 
air quality.
    This is especially true if the SIP identifies a type of project not 
otherwise listed in Sec.  93.123(b)(1) of today's final rule as being 
of air quality concern in the circumstances of a particular area. That 
is, requiring hot-spot analyses to also be completed for types of 
project locations that the SIP identifies will support the SIP's goals 
for an individual area in those cases where a state has the information 
to identify specific types of locations as potential hot-spot concerns. 
Where a state does not have such information, EPA believes that the 
other four regulatory criteria included in today's final rule for when 
analyses are completed sufficiently cover the cases where it is likely 
for a hot-spot to occur.
    EPA again notes that the criterion in Sec.  93.123(b)(1)(v) is 
consistent with a similar criterion in Sec.  93.123(a)(1)(i) of the 
existing rule's requirements for quantitative CO hot-spot analyses. 
That criterion requires quantitative CO hot-spot analyses ``[f]or 
projects in or affecting locations, areas, or categories of sites which 
are identified in the applicable implementation plan as sites of 
violation or possible violation; * * *.''
    Efficient use of state and local resources. Targeting projects of 
air quality concern and eliminating qualitative analyses for projects 
that are not of concern will also streamline conformity determinations 
in PM2.5 and PM10 hot-spot reviews, since the 
majority of proposed projects are not of air quality concern. As a 
result, the final rule will utilize state and local resources in an 
efficient and reasonable manner while still satisfying Clean Air Act 
requirements.
4. Response to Comments
    EPA received many comments regarding what projects should be 
required to have PM2.5 and PM10 hot-spot analyses 
as part of project-level conformity determinations. Many commenters 
believed that the existing and proposed criteria for quantitative hot-
spot analyses were insufficient for meeting Clean Air Act requirements. 
Others only commented on the proposed changes to a specific criterion. 
Many commenters agreed that hot-spot analyses should be focused on 
highway and transit projects involving heavy diesel traffic.
Comment
    Many commenters believed that EPA's proposed regulatory criteria 
for PM2.5 and PM10 hot-spot analyses were 
inadequate. These commenters argued that EPA should specify in the 
conformity rule what types of projects are most likely to cause 
PM2.5 or PM10 hot-spots, and thus where 
quantitative hot-spot analyses should be considered to meet statutory 
requirements. For example, several commenters argued that the final 
regulatory criteria needed to specifically require hot-spot analyses 
for larger highway projects, such as capacity expansions and congested 
intersections with diesel traffic. Another commenter believed that 
heavy diesel traffic at large toll road entrance areas and transit 
tunnel entrances were also a concern, but not specifically addressed by 
the proposed criteria. By establishing more specific regulatory 
criteria, commenters believed all projects of air quality concern will 
meet Clean Air Act requirements by not causing new or more severe or 
more frequent violations, or by not delaying timely attainment.
    Some commenters acknowledged that EPA has already adopted objective 
criteria for when quantitative hot-spot analyses are required for 
certain cases. They cited the current conformity rule's CO quantitative 
hot-spot criteria in Sec.  93.123(a)(1)(ii)-(iv) as a good example for 
establishing objective criteria for PM2.5 and 
PM10 quantitative hot-spot analyses. These commenters also 
supported Sec.  93.123(b)(1)(iii) of the previous conformity rule (now 
covered by Sec.  93.123(b)(1)(iii) and (iv) of today's final rule). 
This criterion, the commenters stated, relied on objective criteria to 
be applied for the circumstances of a given project (i.e., the number 
of diesel vehicles likely to be in an area).
    Two commenters cited several scientific studies that they believed 
showed that highway projects of four lanes or more must be considered 
significant and analyzed under the final rule. Commenters believed that 
studies confirmed that heavily trafficked highways can be expected to 
contribute an increment to urban background of the annual 
PM2.5 standard in the range of 1-3 [mu]g/m3 in 
neighborhoods near the freeway traffic lanes.
    One study cited by commenters was the ``East Bay Children's 
Respiratory Health Study'' (Kim, et al., AJRCCM, Table 2), which showed 
that major freeways contribute at least 3 [mu]g/m3 to 
PM2.5 concentrations in adjacent neighborhoods studied. In 
this study, mean PM2.5 concentrations measured in a school 
yard 60 meters downwind from a freeway with annual average daily trips 
(AADT) of 190,000 was 15 [mu]g/m3, which was 3 [mu]g/
m3 above the levels reported at the regional scale monitors 
operated by air agencies. These commenters concluded that highways of 4 
lanes or larger can be expected to

[[Page 12494]]

contribute at least 1 [mu]g/m3 or more to local 
PM2.5 concentrations. Commenters believed that larger 
highway projects of six lanes or more should be expected to change 
PM2.5 concentrations even further.
    Commenters also cited other information in their comments, and EPA 
notes only a portion of this information here. A study completed by 
Dutch researchers (Netherlands Aerosol Programme, October, 2002), 
commenters believed, was consistent with the East Bay Children's Health 
Study in that highways were estimated to contribute about 3 [mu]g/
m3 at 60 meters from the highway, with the impact tailing 
off to about 1 [mu]g/m3 at 100 meters. In addition, 
commenters cited an April 2004 research project of an interstate in 
downtown Seattle, Washington, where AADT is more than 200,000. The 
project found that the annual mean PM2.5 and black carbon 
concentrations found 20 meters from the interstate were significantly 
higher as compared to another monitoring site 600 meters from the 
interstate.
    Further, some commenters urged EPA to add new regulatory criteria 
that do not rely upon data from existing monitors for the purpose of 
identifying projects that must undergo PM2.5 and 
PM10 hot-spot analyses. Commenters believed that EPA's 
proposed and previous rule's criteria in Sec.  93.123(b)(1)(i) and (ii) 
would not ensure that quantitative analyses would be completed for all 
projects of concern, since sufficient air quality monitoring data does 
not exist to implement these criteria. Two commenters further stated 
that most new major highways, expansions or interchanges will occur at 
sites where no relevant ambient air quality data is available, or where 
current data does not show a violation (although a violation may occur 
when a given project is built). Consequently, the proposed and previous 
criteria in Sec.  93.123(b)(1)(i) and (ii), commenters opined, would be 
arbitrary and capricious since sufficient data is not available to 
identify every potential highway project of concern.
Response
    EPA agrees with the bulk of these comments and has changed the 
final rule in part in response to these comments, as described in EPA's 
rationale above. As stated above, it is essential that a quantitative 
PM2.5 or PM10 hot-spot analysis be performed for 
all projects of air quality concern, as stipulated through the final 
rule's criteria. EPA accomplishes this in the final rule by (1) 
specifically addressing all projects with significant levels of diesel 
traffic, and (2) eliminating previous vague criteria that targeted 
monitoring locations rather than the air quality impacts of projects of 
concern.
    The previous conformity rule's PM10 hot-spot 
requirements and the December 2004's proposed regulatory criteria would 
not have captured all necessary highway projects and possibly resulted 
in an inefficient use of limited state and local resources by requiring 
analyses for projects that are not of concern that are located by 
violating monitors.
    EPA generally agrees with comments that recommend adopting 
regulatory criteria that are similar to the criteria in 40 CFR 
93.123(a)(1). EPA suggested such criteria in its preamble for the 
November 5, 2003 proposal (68 FR 62712) and December 13, 2004 
supplemental proposal (69 FR 72145), where we either cited the CO 
criteria or discussed analyzing heavily congested intersections. 
However, EPA has decided not to finalize specific regulatory criteria 
for quantitative PM2.5 and PM10 hot-spot analyses 
similar to Sec.  93.123(a)(1)(iii) and (iv), which apply to projects 
identified in the SIP as affecting the top three intersections of the 
highest volumes and worst level of service. Such criterion would be 
redundant since the final rule already requires hot-spot analyses for 
projects at large intersections involving significant diesel traffic 
and projects identified in the SIP as an air quality concern.
    EPA has already noted above the types of projects that are most 
likely to be considered projects of air quality concern under today's 
final rule. For example, new highway or expressway facilities that 
serve a significant volume of diesel traffic are considered projects of 
air quality concern under today's final rule.
Comment
    Another commenter stressed the importance of selecting appropriate 
examples of project locations of potential concern in EPA's future 
guidance. This commenter was concerned that the examples given in the 
December 2004 supplemental proposal for PM10 hot-spot 
analyses under proposed Option B concentrated on diesel exhaust 
particulate matter. Although these examples are appropriate for 
PM2.5, this commenter believed that localized 
PM10 concentrations are more likely to be dominated by re-
entrained road dust.
Response
    The final rule will ensure that re-entrained road dust will be 
considered in PM10 hot-spot analyses for projects that have 
the potential to create new or worsen existing air quality violations. 
EPA has determined that these projects of air quality concern are those 
involving significant diesel emissions which is the most critical 
factor in applying a PM10 hot-spot requirement, for reasons 
already stated in this final rule and the original 1993 conformity 
rulemaking (January 11, 1993, 58 FR 3780). In addition, the conformity 
rule requires that road dust be included in all PM10 hot-
spot analyses, as described later in this section.
Comment
    Several commenters supported EPA's proposed clarification to the 
previous rule's Sec.  93.123(b)(1)(iii) (now covered by Sec.  
93.123(b)(1)(iii) and (iv) of the final rule) indicating that 
quantitative PM2.5 and PM10 hot-spot analyses 
would be required for projects that significantly increase the quantity 
of diesel vehicles. EPA also notes that a few commenters supported 
targeting projects addressed by this requirement, such as weight 
inspection stations and bus terminals with significant diesel traffic. 
Commenters also believed that other projects should also be considered 
such as transit maintenance yards, truck stops and school bus terminals 
and maintenance yards.
Response
    The final rule is generally supportive of these comments. The 
interagency consultation process should be used to identify projects 
needing PM2.5 and PM10 hot-spot analyses, and 
EPA's future quantitative modeling guidance will provide further 
information to consider for such analyses. EPA agrees that hot-spot 
analyses should be targeted to projects of air quality concern, which 
involve projects with significant diesel traffic.
Comment
    Some commenters expressed support for the newly proposed criterion 
now in Sec.  93.123(b)(1)(v) of the final rule that would require 
PM2.5 or PM10 hot-spot analyses if the SIP 
identifies other projects of air quality concern. These commenters 
believed that this criterion would support the SIP's air quality goals 
and Clean Air Act conformity requirements in the case where a state 
identified such projects as a hot-spot concern.
    Two of these commenters, however, did not support this criterion if 
it was the sole mechanism for ensuring that projects of concern were 
evaluated for potential PM2.5 or PM10 hot-spots. 
Commenters strongly objected to proposed options (e.g., Option B for 
PM2.5 and PM10 hot-spot analyses after

[[Page 12495]]

SIP submission) to rely upon the SIP to solely identify where hot-spot 
analyses were required for a variety of reasons. For example, 
commenters were concerned that those options depended too heavily on a 
SIP that would not be submitted for several years during which time 
highway projects of concern would be approved that could impact local 
air quality and public health. See Sections III. and IV. of this notice 
for further comments regarding the options cited by commenters.
Response
    EPA agrees with these comments, which are addressed by the final 
rule as described elsewhere in this notice.
Comment
    Some commenters believed that the MPO and the state or local air 
agency should have the opportunity to identify projects to undergo 
quantitative hot-spot analyses. One commenter argued that this 
authority, which should be specifically recognized in Sec.  
93.123(b)(1), is especially important in those portions of 
nonattainment and maintenance areas where small increases in emissions 
may cause a new violation or interfere with an attainment strategy that 
barely achieves attainment.
Response
    EPA agrees that the consultation process--which includes state and 
local transportation and air quality agencies--is critical in 
transportation conformity determinations. EPA has provided examples and 
other information to target projects of air quality concern. Projects 
not of air quality concern are not expected to result in new air 
quality violations, worsen existing violations or delay timely 
attainment of the air quality standards, even in the situations 
described by commenters.
Comment
    Some commenters also believed that EPA should define what projects 
could be ``significant'' and require PM2.5 and PM10 
quantitative hot-spot analyses. There were several variations from 
commenters on this theme, depending on the options EPA proposed and 
would consider in the development of the final rule. A few commenters 
welcomed the opportunity to work with EPA to determine appropriate 
criteria for identifying projects that require quantitative analyses.
    Some commenters suggested that EPA establish significance 
thresholds or a screening methodology that would define when 
quantitative or qualitative hot-spot analyses were required. For 
example, commenters cited significance criteria that New York State and 
New York City have adopted for identifying projects that have a 
``significant'' impact and are required to undergo a detailed impact 
analyses and evaluation of mitigation measures for NEPA purposes.\12\
---------------------------------------------------------------------------

    \12\ These commenters included documentation that New York City 
has adopted guidance requiring an assessment of mitigation measures 
if emissions from a transportation project are expected to add 0.1 
[mu]g/m3 annually, or 5.0 [mu]g/m3 daily of 
PM2.5 to the ambient air.
---------------------------------------------------------------------------

    Two commenters also proposed that highway projects of concern could 
be identified based on specific average daily vehicle trip criteria, 
such as:
     An estimate of daily emissions from a given highway 
segment based upon aggregated hourly emissions expected from traffic 
conditions over the course of current and expected future daily traffic 
patterns for the segment; or
     Traffic loads measured as AADT taking into account the 
variability in emissions that can result from high or low diesel 
vehicle contribution to AADT.
    These commenters provided an example conducted last year by the 
Wisconsin Department of Natural Resources that projected that a 
proposed warehouse and distribution center at which an average of 235 
semi-trailer trucks would arrive and depart each day would contribute, 
on average, 1.6 [mu]g/m3 of PM2.5, and potentially more than 
2.0 [mu]g/m3, to the annual average PM2.5 
standard (Wisconsin DNR memorandum, Revised Air Dispersion Analysis for 
PM2.5 Emissions from Roundy's Warehouse and Distribution Center--
Oconomowoc, April 29, 2004).
Response
    EPA agrees that there should be guidelines for further defining 
which highway or transit projects are considered to have a significant 
number of or a significant increase in diesel vehicles. EPA has 
provided some examples in this notice, along with other commenter 
suggestions. Any project that will cause such a significant number of 
or significant increase in diesel vehicles will require a 
PM2.5 or PM10 hot-spot analysis. EPA and DOT are 
available for further discussions on a particular project.
Comment
    Some commenters requested EPA guidance on what specifically is 
intended by a significant increase in the number of diesel vehicles in 
a location under Sec.  93.123(b)(1)(iii) and (iv) of the final rule. 
One commenter expressed concern that significance be determined solely 
through interagency consultation.
Response
    It is important to consider both the actual number of vehicles 
increased at a project location as well as how this increase relates to 
existing vehicle fleets. For example, a bus terminal expansion that 
increases the number of daily arrivals by more than 50% would be 
significant for an existing bus terminal served by a large fleet. In 
contrast, a 50% increase in daily arrivals at a small terminal (e.g., a 
facility with 10 buses in the peak hour) would not be significant. 
Areas should consider the circumstances involved at an individual 
project's location, including the total vehicle increase and how such 
an increase compares to the size of the existing diesel fleet for a 
given project location. Areas should also consider the type of vehicles 
that are added to an area either through a brand new or expanded 
existing terminal. As noted above, this final rule specifies projects 
of air quality concern as terminals or transfer points involving diesel 
vehicles. Projects involving new or expanded fleets of compressed 
natural gas or hybrid electric vehicles would not be considered to be 
projects of air quality concern.
Comment
    Another commenter stated that, for intersections, a clear, 
scientifically based criterion for ``highly congested'' is needed. The 
commenter gave as examples studies done for the California Department 
of Transportation by the University of California, Davis, in the 1990's 
which failed to find a clear indication of PM10 hot-spots 
near two major intersections with higher traffic volumes and levels of 
congestion than in other areas. The commenter stated that it is still 
unclear at what level of congestion and volume the potential for an 
intersection hot-spot would arise. The commenter believed that 
additional research and technical review is needed before reasonable 
analysis methods (including changes to emission models to better fit 
microscale analysis needs) for such situations can be defined.
Response
    This commenter is referring to the examples of projects provided in 
the December 2004 supplemental proposal that could possibly be 
identified under an option that solely relied on the SIP to identify 
projects needing quantitative hot-spot analyses (e.g., Option B). The 
examples included ``highly congested intersections.''
    EPA is finalizing instead a criterion that was discussed in the 
November 2003 proposal and is more similar to the

[[Page 12496]]

current conformity rule's Sec.  93.123(a)(1)(ii) which involves 
projects in CO areas at intersections of Level-of-Service D, E, and F. 
However, the final rule only requires PM2.5 or 
PM10 hot-spot analyses of such projects involving 
significant levels of diesel traffic. This final rule does not require 
a PM2.5 or PM10 hot-spot analysis for projects at 
intersections of Level-of-Service D, E, and F that are used primarily 
by gasoline vehicles. EPA has provided other examples of what a 
significant level of diesel vehicles could include elsewhere in this 
notice.
Comment
    Another commenter stated that ports and airports should also be 
included in the list of projects that require an analysis for potential 
PM2.5 and PM10 hot-spots. This commenter felt 
that potential air quality impacts from ports and airports need to be 
carefully considered to enable economic growth while ensuring 
appropriate mitigation of emission increases and that ports, their 
transportation support systems, and airports are also often located in 
areas with sensitive populations and environmental justice concerns.
Response
    EPA has not addressed port and airport projects funded or approved 
by the Federal Aviation Administration (FAA) and other federal agencies 
in this final rule, because these types of projects are not covered by 
the transportation conformity rule. These projects are covered by the 
general conformity rule.
    However, EPA notes that any transit or highway projects that are 
intended to service transportation to and from a port or airport 
project would be addressed by transportation conformity, and may 
require PM2.5 or PM10 hot-spot analyses if they 
are a project of air quality concern under Sec.  93.123(b)(1).
Comment
    A commenter supported EPA and DOT developing a list of ``exempt'' 
projects that would not require quantitative hot-spot analyses. The 
commenter also suggested that further consideration should be given to 
refine a list of projects or situations that can be tested through 
qualitative hot-spot analyses as agreed upon through the consultation 
process. One commenter noted that only qualitative PM2.5 and 
PM10 hot-spot analyses would be possible prior to the 
development and release of quantitative methods.
Response
    EPA has addressed this comment in part by removing the requirement 
to perform qualitative hot-spot analyses for projects that are not an 
air quality concern. As described in Sections III. and IV., these 
qualitative analyses for projects that are not expected to impact air 
quality violations are not an efficient use of state and local 
resources, in light of past practice indicating that no such analyses 
have ever found a hot-spot problem in such areas. EPA agrees with the 
commenter that qualitative hot-spot analyses will be required for 
projects of concern before quantitative guidance and tools are 
available. Finally, future categorical hot-spot findings, as described 
in Section VII., could possibly streamline hot-spot requirements 
further for certain projects if it is found that additional analyses 
are not needed to meet statutory requirements.

C. General Requirements

1. Description of Final Rule
    EPA is retaining for PM10 areas and extending for 
PM2.5 areas the general requirements in Sec.  93.123(c) for 
hot-spot analyses of projects of air quality concern. EPA did not 
propose any substantive changes to these requirements, which are:
     Analyzing the total emissions burden of direct 
PM2.5 and PM10 emissions which may result from 
the implementation of the project (including re-entrained road dust and 
construction dust, as described below), summed together with future 
background concentrations;
     Analyzing the entire transportation project, after the 
identification of major design features which will significantly impact 
local concentrations;
     Using consistent assumptions with those used in regional 
emissions analyses for inputs that are required for both analyses 
(e.g., temperature, humidity);
     Assuming the implementation of mitigation or control 
measures only where written commitments for such measures have been 
obtained; and
     Not considering temporary emissions increases from 
construction-related activities which occur only during the 
construction phase and last five years or less at any individual site.
    Re-entrained road dust would be included in all PM10 
hot-spot analyses, since fugitive dust dominates PM10 
inventories. EPA has historically required road dust to be considered 
in all PM10 conformity analyses. In contrast, road dust 
emissions are only to be considered in PM2.5 hot-spot 
analyses if EPA or the state air agency has made a finding that such 
emissions are a significant contributor to the PM2.5 air 
quality problem (40 CFR 93.102(b)(3)). EPA has provided more 
information later in this section in response to a comment on including 
fugitive dust in PM2.5 or PM10 hot-spot analyses.
    EPA continues to believe that construction dust emissions from a 
particular project would not be included in a PM2.5 or 
PM10 hot-spot analysis, if such emissions are considered 
temporary as defined in Sec.  93.123(c)(5). Further information on 
including non-temporary construction emissions for certain projects is 
discussed further below.
    EPA is also extending the requirements of Sec.  93.125(a) for all 
projects in PM2.5 nonattainment and maintenance areas that 
rely on control or mitigation measures in project-level conformity 
determinations. As described in the November 2003 and December 2004 
proposals, FHWA or FTA must obtain from the project sponsor and/or 
operator enforceable written commitments to implement any required 
project-level control or mitigation measures, prior to making a 
project-level conformity determination for projects in PM2.5 
nonattainment or maintenance areas. The final rule does not revise the 
existing commitment requirement for projects in PM10 areas.
    In its previous proposals, EPA had implied that Sec.  93.125(a) 
might only be relevant for proposed options that would require 
PM2.5 and PM10 hot-spot analyses. EPA is 
clarifying in today's preamble that Sec.  93.125(a) applies to all 
project-level conformity determinations that involve projects with 
control or mitigation measures that are:
     Identified as conditions for the NEPA process;
     Identified as conditions for a transportation plan or TIP 
conformity determination's regional emissions analysis; or
     Used in a project-level hot-spot analysis.
Of course, today's final rule does not require any control or 
mitigation measures for project-level conformity determinations in 
PM2.5 areas; it simply requires that sufficient commitments 
be in place if there happen to be any measures for a given project 
before a PM2.5 project-level conformity determination is 
made.
    EPA does not expect this clarification in today's preamble to have 
a practical impact on project implementation. Today's final rule does 
not change the regulatory text that was proposed for Sec.  93.125(a). 
Again, adding a reference for PM2.5 to Sec.  93.125(a) 
simply provides

[[Page 12497]]

added enforcement of measures if any exist for projects in 
PM2.5 areas.
    Today's final rule also includes minor clarifications with respect 
to PM2.5 to various parts of the current conformity rule 
that are consistent with existing CO and PM10 hot-spot 
analysis requirements. For example, EPA is adding PM2.5 to 
the current rule's ``hot-spot analysis'' definition in Sec.  93.101. 
This and other clarifications were proposed in regulatory text in the 
December 2004 supplemental proposal.
2. Rationale
    EPA is extending to PM2.5 areas the current conformity 
rule's general requirements for conducting PM10 hot-spot 
analyses. These changes for PM2.5 do not substantively 
change these PM10 provisions of the current conformity rule 
(e.g., Sec. Sec.  93.123(c) and 93.125(a)), but rather just apply these 
requirements to PM2.5. These provisions are intended to 
produce credible analyses for whether project emissions create new or 
worsen existing air quality violations. EPA intends that the hot-spot 
analysis compare concentrations with and without the project based on 
modeling conditions in the analysis year. The hot-spot analysis is 
intended to assess possible violations due to the project in 
combination with changes in background levels over time. Estimation of 
background concentrations may take into account the effectiveness of 
any anticipated control measures if they are enforceable and 
creditable.
    EPA also believes that conformity should address long-term 
emissions from the transportation system, and that conformity should 
not prevent project implementation because of temporary emissions 
increases. In addition, the NEPA process provides the most appropriate 
forum to analyze construction-related emissions impacts and to 
establish mitigation measures. PM2.5 and PM10 
hot-spot analyses would not have to include construction-related 
activities which cause temporary and self-correcting increases in local 
concentrations, which are defined under the existing and today's final 
rule as those which occur only during the construction phase and last 
five years or less at any individual site. See the preamble for the 
January 1, 1993 proposal (58 FR 3779-3780) and November 24, 1993 final 
rule (58 FR 62212-62213) for further information regarding the intent 
and rationale for these general hot-spot requirements.
3. Response to Comments
    EPA received a limited number of comments on the general 
requirements for performing PM2.5 and PM10 hot-
spot analyses.
Comment
    One commenter supported the EPA proposal that Sec.  93.123(c) 
requirements should be maintained in an effort to develop continuity 
between analysis efforts. The commenter further agreed that Sec.  
93.125(a) requirements should be applied to PM2.5 hot-spot 
analyses so that the implementation of any project-level control or 
mitigation measure is assured.
Response
    EPA agrees for the reasons cited by the commenter. The existing 
requirements have a proven track record since the original 1993 
conformity rule for providing credible and reasonable hot-spot 
analyses.
Comment
    However, another commenter disagreed with EPA's proposal to apply 
Sec. Sec.  93.123(c)(4) and 93.125(a) to PM2.5 hot-spot 
analyses since PM2.5 SIP measures are already enforceable as 
a matter of law based on the Clean Air Act and the NEPA process. The 
commenter argued that EPA should reevaluate its previous rulemaking 
decisions on compliance with PM2.5 and PM10 SIP 
control measures in 40 CFR 93.117 because these requirements are 
duplicative and unnecessary.
Response
    EPA disagrees with this comment and believes that the conformity 
rule is the appropriate context for meeting all Clean Air Act 
conformity requirements. Implementation and enforcement of measures can 
be an important part of reducing emissions for projects, when 
necessary. Without assurance that such measures will be implemented, it 
is not possible to accurately predict what emissions may be for 
project-level conformity determinations, and whether or not projects 
meet statutory requirements.
    EPA also acknowledges that, though these control measures would 
already be applicable to such projects through NEPA and other 
mechanisms, including commitments to them in conformity determinations 
provides an additional enforcement tool that, at times, may be 
necessary.
Comment
    EPA also received comments regarding when Sec.  93.123(c) requires 
fugitive dust to be included in PM2.5 or PM10 
hot-spot analyses. Some commenters did not believe that road dust 
should be included in PM2.5 or PM10 hot-spot 
analyses due to lack of state and local information on the importance 
of dust emissions on air quality. They also argued that road dust 
should only be included in PM2.5 hot-spot analyses if road 
dust has been found to be a significant contributor to the 
PM2.5 air quality problem (40 CFR 93.102(b)(3)). Commenters 
submitted several documents that supported their judgement that further 
research was needed to make decisions regarding significance of road 
dust for PM2.5 areas. The commenters agreed with the 
existing conformity rule's provisions for using the interagency 
consultation process for deciding whether road dust is significant for 
a given PM2.5 area.
    Another commenter believed that EPA's December 2004 supplemental 
proposal was incorrect in stating that there could be cases where 
highway and transit construction emissions from an individual project 
would be included in a PM2.5 or PM10 hot-spot 
analysis pursuant to Sec.  93.123(c)(1). This commenter also cited 
Sec.  93.123(c)(5)'s requirement that PM hot-spot analyses not include 
temporary increases in emissions caused by construction-related 
activities that last 5 years or less at any individual site.
Response
    EPA agrees with some of these comments. In the preamble to the 
December 2004 supplemental proposal, EPA described applying Sec.  
93.123(c)(1) requirements to PM2.5 or PM10 hot-
spot analyses while including re-entrained road dust and construction 
emissions in such analyses only ``as applicable'' (69 FR 72146). 
However, EPA did not elaborate on this caveat in its proposal, so 
further clarification in today's notice is warranted. Whether or not to 
include road or construction dust in PM2.5 or 
PM10 emissions analyses are addressed by different 
provisions in the existing conformity rule.
    Section 93.102(b)(3) states that re-entrained road dust is to be 
considered in any PM2.5 conformity determination, including 
PM2.5 hot-spot analyses, if road dust has been found to be a 
significant contributor to the PM2.5 air quality program in 
a given area. In its July 1, 2004 final rule, EPA highlighted this 
requirement in the context of including such dust emissions in plan and 
TIP regional emissions analyses. However, Sec.  93.102(b)(3) defines 
more broadly what types of emissions are considered in all types of 
conformity determinations for a given pollutant and precursor, and 
consequently, only requires PM2.5 hot-spot analyses to 
include road dust emissions if such emissions have been found 
significant

[[Page 12498]]

through a finding of significance prior to the PM2.5 SIP or 
as part of an adequate PM2.5 SIP motor vehicle emissions 
budget.
    However, EPA disagrees that re-entrained road dust would not be 
included in a PM10 hot-spot analysis, when performed in a 
PM10 nonattainment or maintenance area. Since the 1993 
conformity rule was promulgated, EPA has intended for road dust 
emissions to be included in all conformity analyses of direct 
PM10 emissions because fugitive dust from roadways and other 
sources dominate PM10 emissions inventories. To that end, 
the conformity rule does not include an exception for when road dust 
emissions are not included in PM10 hot-spot analyses, like 
the exception for such emissions in PM2.5 analyses in 40 CFR 
93.102(b)(3). By definition, PM10 includes larger particles 
from fugitive dust including roadway sources, whereas the role of re-
entrained road dust for PM2.5 air quality issues is less 
clear (November 5, 2003, 68 FR 62709).
    As described above, EPA continues to believe that construction dust 
emissions would not be included in PM2.5 and PM10 
hot-spot analyses, if such emissions are considered temporary as 
defined by Sec.  93.123(c)(5). In most cases, EPA anticipates that 
construction emissions would not be included in hot-spot analyses 
because they would be considered temporary. However, there may be 
limited cases where a large project is constructed over a longer time 
period where it may be appropriate to include any non-temporary 
construction emissions, when an analysis year is chosen in which 
construction of the project is still occurring.
Comment
    Another commenter believed that PM2.5 and 
PM10 hot-spot analyses need to meet existing requirements 
for up-to-date and reasonable conformity analyses. The commenter 
specifically cited 40 CFR 93.110 and 93.122 as requiring the latest 
planning assumptions in conformity analyses and reasonable assumptions 
regarding land use projections in regional emissions analyses. 
Furthermore, the commenter believed that EPA should clarify that hot-
spot analyses must be based on honest and accurate assumptions and 
include trip distribution and land use changes in order to meet 
statutory requirements.
    The commenter also argued that project analyses are currently 
inadequate because they rely on unrealistic assumptions for no-build 
cases, and ultimately, understate emissions impacts. This commenter 
believed that almost all transportation agencies apply the growth and 
land use assumptions from the build case also to the no-build case, 
which was found to be inappropriate in a previous court decision. The 
commenter cited EPA's January 2001 guidance entitled, ``Improving Air 
Quality Through Land Use Activities,'' which recommends the interagency 
consultation be used for agencies to agree to use the most reasonable 
and best available assumptions.
Response
    EPA agrees that PM2.5 and PM10 hot-spot 
analyses must be based on the latest planning and land use development 
assumptions before and after a project is expected to be implemented in 
a given analysis year. To do otherwise would not produce credible hot-
spot analyses that meet Clean Air Act requirements. Section 
93.105(c)(1)(i) of the existing conformity rule requires the 
interagency consultation process to be used to evaluate and choose 
models and associated methods and assumptions to be used in 
PM2.5 and PM10 hot-spot analyses.

VI. Timing of PM2.5 and PM10 Quantitative Hot-
spot Analyses and Development of Future Guidance

A. Description of Final Rule

    EPA is finalizing its proposal to not apply quantitative 
PM2.5 and PM10 hot-spot requirements until EPA 
releases quantitative modeling guidance and announces in the Federal 
Register that such requirements are in effect. This action extends the 
existing conformity rule's Sec.  93.123(b)(4) requirements for 
PM10 areas to also cover PM2.5. EPA will consult 
with conformity stakeholders when developing its future quantitative 
modeling guidance.

B. General Rationale

    EPA is finalizing the proposal because we continue to believe that 
appropriate tools and guidance are necessary to ensure credible and 
meaningful quantitative PM2.5 and PM10 hot-spot 
analyses. Before such analyses can be performed, technical limitations 
in applying existing motor vehicle emission factor models must be 
addressed, and proper federal guidance for using dispersion models for 
PM hot-spot analysis must be issued, as described further below.

C. Rationale and Response to Comments About Motor Vehicle Emissions 
Factor Models

1. Rationale
    On February 24, 2004, EPA released MOBILE6.2 as the approved motor 
vehicle emissions factor model for SIP and conformity purposes outside 
of California, where EMFAC2002 is the most recently EPA-approved model 
for that state. With the release of MOBILE6.2, state and local 
transportation agencies now have an approved model for estimating 
regional PM2.5 and PM10 emissions factors in SIP 
inventories and regional emissions analyses for transportation 
conformity. However, MOBILE6.2 has significant limitations that make it 
unsatisfactory for use in microscale analysis of PM2.5 and 
PM10 emissions as necessary for quantitative hot-spot 
analyses. To understand those limitations it is necessary to compare 
how emissions of CO, hydrocarbons (HC), and NOX are 
calculated in MOBILE6.2 with the methods used to calculate 
PM2.5 and PM10 emissions.
    EPA has incorporated CO, HC, and NOX emissions in MOBILE 
from the very first version of the model. EPA has had many years to 
collect data and refine the methodologies used to estimate emissions of 
these pollutants. As a result, MOBILE6.2 incorporates adjustments for 
the effects on CO, HC, and NOX emissions of environmental 
conditions, such as temperature, humidity, altitude; fleet 
characteristics, such as age distribution and mileage accumulation by 
age; activity impacts, such as speed and road type (i.e, driving 
cycle); and fuel characteristics, such as fuel sulfur level. These 
adjustments are incorporated as local input options in MOBILE6.2 and 
changes in any of them can have significant affects on emissions of CO, 
HC, and NOX as determined by the model. Therefore, 
quantitative CO hot-spot analyses have been required since the original 
1993 conformity rule because the MOBILE model has been appropriate for 
these analyses in project-level conformity determinations for CO areas 
(40 CFR 93.123(a)).
    In contrast, emissions estimation for PM2.5 and 
PM10 was only added to MOBILE6.2 in 2004.\13\ Because EPA 
has not since then developed sufficient databases of vehicle 
PM2.5 or PM10 emissions that are as complete as 
those for CO, HC, and NOX, the algorithms used in MOBILE6.2 
for estimating PM emissions are much simpler than those

[[Page 12499]]

used for CO, HC, and NOX. While MOBILE6.2 has the same input 
options for PM as for the other pollutants, most of those input options 
do not have any affect on PM2.5 or PM10 emission 
estimates calculated by the model. For example, there are no 
temperature, humidity, or altitude corrections in MOBILE6.2 for 
PM2.5 or PM10. Speed, driving cycle, engine 
starts, and all of the other activity input options similarly have no 
affect on PM2.5 or PM10 emissions in MOBILE6.2. 
The only conditions that do affect PM2.5 or PM10 
emissions in MOBILE6.2 are fleet and fuel characteristics.
---------------------------------------------------------------------------

    \13\ PM10 emissions were previously estimated using 
an EPA model called PART5, which had the same limitations described 
here for MOBILE6.2.
---------------------------------------------------------------------------

    EPA has already determined that these limitations are not a 
substantial problem for regional scale emissions estimation needed for 
PM2.5 and PM10 SIP inventories and regional 
emissions analyses for conformity. MOBILE6.2 does account for the 
effects of vehicle standards and the impacts of fleet turnover. Growth 
in activity is also accounted for in projections of future VMT which 
are multiplied by emission factors to derive emissions inventories. 
While it is desirable to include other activity effects such as speed 
and driving cycle, differences in these inputs are generalized over a 
larger area in a regional analysis. Even in the absence of data and 
methods to derive adjustment factors for these effects, EPA believes 
that MOBILE6.2 is an adequate tool for evaluation of PM2.5 
and PM10 emissions at the regional level.
    However, at the micro-scale level needed for hot-spot analyses, 
these limitations become very significant. Activity factors such as 
speed, driving cycle, and number and distribution of engine starts per 
day do have an important impact on actual PM2.5 or 
PM10 emissions from motor vehicles. Most, if not all, 
transportation projects that would need to be analyzed would result in 
changes in these activity levels that would need to be incorporated in 
credible hot-spot analyses. For example, the construction of a highway 
interchange would likely result in significant changes to average 
speeds, driving cycles of vehicles, idling time, etc. in the immediate 
vicinity of the interchange. The effects of these changes are an 
important and necessary component of estimating the impact of the new 
interchange on nearby PM2.5 or PM10 
concentrations, but none of these changes can be accounted for in the 
currently available emissions factor models.
    Likewise, the mitigating effects of potential control measures that 
smooth traffic flow, such as synchronization of traffic signals, cannot 
be accounted for in existing models. These limitations apply even to 
projects where changes in vehicle speed are less of an issue. For 
example, long duration idling emissions are also poorly accounted for 
in MOBILE6.2. As a result, it is not an adequate tool for assessing the 
localized impacts of individual projects such as bus, rail or freight 
terminals, or potential mitigation measures for incorporation into such 
projects.
    EPA is working to resolve limitations in MOBILE6.2 through a major 
data collection and model development effort. As part of that effort, 
EPA is collecting data on real-world environmental and activity effects 
on emissions for all pollutants, including PM2.5 and 
PM10. The next version of EPA's motor vehicle emissions 
model (called MOVES) will incorporate PM2.5 or 
PM10 adjustments for environmental and activity conditions 
(including long-duration idling) that are currently missing in 
MOBILE6.2, and relevant to hot-spot modeling as described above. MOVES 
will be specifically designed to work at both the regional and micro-
scale level. EPA believes that MOVES will provide the level of detail 
needed for credible and meaningful PM2.5 or PM10 
hot-spot analysis. A draft version of MOVES that incorporates new 
emissions information for motor vehicles is expected in 2006 with a 
final version in 2007.
    EPA also believes that both an appropriate motor vehicle emissions 
factor model and EPA's guidance on applying air quality models is 
necessary before quantitative PM2.5 and PM10 hot-
spot modeling guidance can be required in California. While EPA has 
approved EMFAC2002 for PM2.5 and PM10 regional 
emissions analysis in California, we do not currently have enough 
information about how it handles vehicle activity effects on 
PM2.5 or PM10 emissions to make a determination 
of its applicability to quantitative PM2.5 and 
PM10 hot-spot analyses. EPA will evaluate the applicability 
of EMFAC2002 for quantitative PM2.5 and PM10 hot-
spot analyses in the context of EPA's future quantitative modeling 
guidance.
2. Response to Comments
    EPA received several comments directed at the application of motor 
vehicle emissions models in quantitative PM2.5 or 
PM10 hot-spot analyses.
Comment
    Some commenters agreed that the current modeling tools do not have 
the ability to evaluate PM2.5 for hot-spot analyses 
adequately. They believed that MOBILE6.2 is insensitive to many 
variables likely to affect localized PM2.5 emissions, 
specifically speed and drive cycles. One commenter supported EPA's 
development of MOVES since it will provide for better PM2.5 
and PM10 analyses in the future. Some of these commenters 
also noted that implementors will now have time to gather data and 
obtain experience for conducting future quantitative analysis of PM 
emissions.
Response
    EPA agrees with these comments for the reasons given above and 
therefore has not required quantitative hot-spot analyses until 
appropriate tools and EPA guidance are available.
Comment
    Other commenters strongly disagreed with EPA's proposed approach to 
extend Sec.  93.123(b)(4) to PM2.5 hot-spot analyses. 
Commenters argued that the absence of emissions factors was the single 
greatest obstacle to modeling PM2.5 motor vehicle emissions, 
and now that EPA has released MOBILE6.2, there is no basis for further 
delaying a requirement that emissions from highways be quantified and 
assessed as part of a project-level conformity determination. Most of 
these commenters argued that continuing to delay quantitative 
PM2.5 or PM10 hot-spot analyses for 
transportation projects is unjustified, given that great advancements 
in modeling tools have been made since the publication of the original 
1993 conformity rule. Because EPA has required the use of MOBILE6.2 for 
SIP development and regional emissions analyses, one commenter also 
believed it would be unlawful not to require its use in 
PM2.5 and PM10 hot-spot analyses.
Response
    EPA disagrees with these commenters based on the technical 
limitations of using MOBILE6.2 for hot-spot analyses as discussed in 
detail above. The use of MOBILE6.2 in hot-spot analyses will produce 
inaccurate results in some cases. For example, a project that would 
actually result in lower net emissions due to traffic flow 
improvements, would appear to result in an increase in emissions in an 
analysis done using MOBILE6.2 if the project also resulted in some 
increase in activity. This is because MOBILE6.2 is insensitive to the 
effects of changes in speed for PM2.5 or PM10. At 
the same time, a project that actually results in increased emissions 
due to increased long-duration idling, might appear to have no impact 
on emissions given that MOBILE6.2 does not properly account for long-
duration

[[Page 12500]]

idling emissions. Further, EPA does not believe that it can be assumed 
that a model is appropriate for a hot-spot analysis simply because EPA 
has approved a model for regional analyses. Any model EPA approves must 
be appropriate for the use to which it will be put. For all the reasons 
explained above, MOBILE6.2 is not appropriate for PM2.5 or 
PM10 hot-spot analyses despite the fact that it may be 
appropriate for regional analyses of those pollutants.
Comment
    One of these commenters also referenced text from pages 40-41 of 
EPA's August 2004 ``Technical Guidance on the Use of MOBILE6.2 for 
Emission Inventory Preparation'' as evidence that MOBILE6.2 can be used 
to estimate emissions from individual transportation projects.
Response
    The commenter incorrectly interpreted the specific text referenced 
in the MOBILE6.2 technical guidance that describes how the model can be 
used to account for differences in emissions by roadway type. Although 
this input accounts for the differences in emissions in stop-and-go 
driving as on an arterial street and continuous speed driving as on a 
freeway, those differences only apply to the estimation of CO, HC, and 
NOX emissions. PM10 and PM2.5 
emissions are not effected by these inputs. As described above, 
differences in emissions by the type of driving that will occur are 
critical to analyses of individual projects and MOBILE6.2 cannot 
account for these differences for PM2.5 or PM10 
hot-spot analyses.

D. Rationale and Response to Comments About Dispersion Models and Other 
Modeling Issues

1. Rationale
    In order to complete appropriate hot-spot modeling, EPA needs to 
specify which air quality dispersion models are appropriate for 
transportation projects and provide additional guidance for estimating 
PM2.5 and PM10 concentrations at the local level. 
Dispersion models estimate air quality concentrations based on the 
emissions produced by a particular project (which will be provided in 
part through models like MOVES) and the background concentrations 
assumed at a project location. There are currently many different 
dispersion models that are being used for air quality modeling, 
including modeling of localized air quality impacts for other 
pollutants. However, as described further below, EPA believes that it 
must first release quantitative modeling guidance that describes how to 
apply existing air quality dispersion models to result in credible 
PM2.5 and PM10 hot-spot analyses.
2. Response to Comments
Comment
    Many commenters supported the final rule approach because they 
believed that EPA guidance is essential for highlighting which 
dispersion models are appropriate and for addressing other modeling 
issues. Some commenters requested clarification on whether hot-spot 
analyses would be compared to the PM2.5 or PM10 
annual or daily standards. Some commenters agreed that guidance is also 
necessary for the projection of future travel activity levels and 
future background concentrations. Other commenters believed that the 
issuance of guidance would provide modeling consistency and eliminate 
redundancy across the country.
Response
    EPA agrees with these comments for the reasons cited by the 
commenters. EPA believes that the future hot-spot modeling guidance 
will provide information that will be essential for addressing PM-
specific modeling issues, which some commenters supported. In addition, 
as stated elsewhere in this section, EPA also believes that its future 
development of the MOVES model is essential to providing credible 
PM2.5 and PM10 hot-spot analyses.
Comment
    Other commenters believed Sec.  93.123(b)(4) was originally 
included in the 1993 conformity rule with EPA's commitment to issue 
timely guidance on quantitative hot-spot analyses, which has not 
occurred. These commenters were very concerned that finalizing the 
proposal would create a loophole for delaying quantitative PM hot-spot 
analyses for projects that could negatively impact air quality and 
public health. These commenters believed that adequate dispersion 
models are already available for PM2.5 and PM10 
quantitative hot-spot analyses, and no additional EPA guidance is 
needed before requiring such analyses. Another commenter believed that 
quantitative hot-spot analyses of transportation projects should either 
apply immediately upon promulgation of the final rule or within a short 
period of time after promulgation (e.g., 120 days), if EPA has not yet 
issued quantitative modeling guidance by that time.
Response
    Although EPA agrees with commenters that quantitative 
PM2.5 and PM10 hot-spot analyses are critical for 
considering the public health implications of transportation projects, 
we strongly disagree with commenters' conclusions. EPA is not using the 
release of its future hot-spot modeling guidance to delay credible and 
meaningful quantitative PM2.5 or PM10 hot-spot 
analyses. In fact, requiring such analyses now without having all 
models and EPA's guidance available could result in analyses that are 
not credible and waste limited state and local resources.
    EPA agrees that adequate air quality dispersion models may be 
available, but having such models is only one aspect of conducting 
credible PM2.5 or PM10 hot-spot analyses. As 
described in C.1. of this section, adequate dispersion models alone are 
not enough to conduct credible PM2.5 or PM10 hot-
spot analyses; adequate motor vehicle emissions factors and guidance 
for using motor vehicle emissions factor and dispersion models is also 
needed. The results from dispersion models would not be reliable for 
PM2.5 and PM10 estimates if the emission factor 
models used to provide input (such as MOBILE6.2) do not provide 
sufficient detail to distinguish changes in activity factors.
    Nevertheless, even if the emission factor models did provide this 
level of detail, EPA would still need to provide guidance on the 
application of dispersion models in determining whether a 
PM2.5 or PM10 hot-spot will occur. Dispersion 
models are complicated tools that, if used incorrectly, could result in 
incorrect conclusions about the impact of an individual project's 
localized concentrations. For example, the location of model receptors 
is particularly important in dispersion modeling of PM2.5 
and PM10 emissions. If the receptors are predominately 
upwind of the project being analyzed, it could lead to false 
conclusions about the likelihood of a violation. Guidance is also 
needed on making model output comparable to the relevant form of the 
air quality standards, and to EPA regulations and guidance for 
PM2.5 monitoring for the 24-hour and annual PM2.5 
standards.
    Another important factor in dispersion modeling is the choice of 
meteorological data used in PM2.5 and PM10 hot-
spot analyses. Areas need guidance in how to choose meteorological 
conditions that are properly representative of conditions

[[Page 12501]]

that might result in a violation. Without proper guidance, areas might 
choose to use meteorological data that lead to under-or over-predicting 
the likelihood of a violation.
    Guidance is also necessary to describe how the projection of future 
travel activity levels and future background concentrations can be used 
as inputs to dispersion modeling. Projects need to be analyzed based on 
assumptions that they are fully utilized, or are experiencing maximum 
predicted emissions, rather than projections of use when they first 
open. Likewise, dispersion modeling has to take into account projected 
changes in background PM2.5 and PM10 
concentrations.
    These are just a few examples of the kinds of issues that modelers 
will face when developing PM2.5 and/or PM10 hot-
spot analyses. EPA is currently researching these kinds of issues so 
that currently available dispersion models can be applied appropriately 
for PM2.5 and PM10 hot-spot analyses. Without 
having all necessary models and detailed guidance, EPA cannot have 
reasonable assurance that the results of dispersion modeling in hot-
spot analyses will be consistent and credible throughout the country, 
and ensure that all projects will meet statutory requirements.
Comment
    Two commenters cited a recent paper \14\ on modeling toxic 
emissions which they interpret as providing strong evidence that 
currently available dispersion models are suitable for estimating local 
PM concentrations. Toxic air pollutants include non-reactive gases that 
would disperse like CO, and others that are aerosols that would 
disperse as particles in the ambient air.
---------------------------------------------------------------------------

    \14\ Robert G. Ireson, ``Dispersion Modeling for Mobile Source 
Air Toxics Exposure,'' (January 9, 2005) Transportation Research 
Board's 84th Annual Meeting of Air Quality Management Consulting.
---------------------------------------------------------------------------

Response
    As discussed in the previous response, EPA agrees that current 
dispersion models may be suitable for estimating PM2.5. or 
PM10 concentrations, provided that accurate emissions inputs 
are available for the dispersion models and that the models are used 
properly, as will be addressed in EPA's future quantitative modeling 
guidance. The limitations of existing emissions information for 
localized analysis have already been discussed in detail in C.1 of this 
section. The need for additional guidance on dispersion models is 
further discussed in this section.
Comment
    Three commenters recommended that new regulatory language be added 
to the conformity rule to require that ``state-of-the-art'' modeling 
tools be used to conduct PM2.5 or PM10 hot-spot 
analyses as determined through the interagency consultation process. By 
having model selection determined through consultation, a commenter 
believed that EPA would have an opportunity to provide guidance on 
specific details even if formal guidance has not yet been issued.
Response
    EPA disagrees with this general approach. The significant technical 
limitations in MOBILE6.2 discussed in C.1. of this section cannot 
simply be resolved through interagency consultation, and EPA's future 
modeling guidance will ensure that credible analyses are conducted. 
However, once an appropriate motor vehicle emissions model and EPA's 
future guidance is available, EPA agrees that the consultation process 
will play an important role in performing PM2.5 or 
PM10 hot-spot analyses. Section 93.105(c)(1)(i) of the 
conformity rule already requires that consultation be used to evaluate 
and choose models and associated methods and assumptions for hot-spot 
analyses. Such consultation must be consistent with the use of EPA-
approved motor vehicle emissions models and our future guidance.
Comment
    One commenter stated that PM2.5 source apportionment 
techniques should first be improved, and that models that simulate the 
chemistry and transport of PM2.5 should be validated at the 
microscale level before hot-spot modeling is required. This same 
commenter also noted that MOBILE6.2 estimates that low-sulfur diesel 
fuel and cleaner vehicles, due to the phase-in of Tier 2 and federal 
heavy duty engine standards, will dramatically reduce PM2.5 
emissions in the future. Therefore, this commenter implied that 
PM2.5 hot-spots may not be as much of a concern once 
PM2.5 source apportionment techniques and chemical/
dispersion models are available, since by that time on-road mobile 
sources may only represent a small fraction of PM2.5 
emissions in nonattainment areas.
Response
    PM source apportionment is not a relevant technique for project-
level air quality modeling, because it pertains to current, observed 
outdoor PM measurements. The air quality impacts of those 
transportation projects that are relevant to a conformity determination 
are estimated in the future, when actual monitoring data is not 
available. As such, source-oriented models that use emissions estimates 
and run them through an air quality model are the only appropriate 
tools for projecting future-year impacts of transportation projects. 
The second part of this comment suggests that chemical transport models 
are required for microscale analysis. However, over the time during 
which air parcels pass from a transportation project to a location 
several hundred meters downwind, where PM hot-spots could be a concern, 
there is insufficient time for chemical reactions to affect PM mass 
concentrations. Dispersion models have been used for this purpose in 
the past, and have been evaluated in the scientific literature. The 
commenter is correct that PM2.5 emissions from motor 
vehicles are expected to decline in the future as a result of new 
vehicle standards and fuels. However, the impact of those new standards 
is gradual and does not preclude the possibility of PM hot-spot 
problems in the future.
Comment
    Two commenters noted that existing tools have already been used in 
a few cases for localized NEPA analyses for PM10, which they 
argued supported the mandatory application of these tools for all 
PM10 and PM2.5 hot-spot analyses.
Response
    EPA disagrees. While it is true that these analyses were done on a 
voluntary basis, it is not clear how well these analyses would stand up 
to review if there was a mandatory requirement for quantitative 
PM2.5 or PM10 hot-spot analyses, for the 
technical reasons discussed above.

E. Process and Timing for Developing Guidance

    As described above, EPA is working to resolve the limitations in 
MOBILE6.2 as part of the development of MOVES, EPA's new emissions 
model for mobile sources. As described above, EPA is currently 
collecting and analyzing data, while simultaneously developing the 
MOVES model itself. A draft version of MOVES that incorporates new 
emissions information for motor vehicles is expected in 2006 with a 
final version in 2007. MOVES will undergo both stakeholder and peer 
review. More information on MOVES can be found at http://www.epa.gov/otaq/ngm.htm. EPA

[[Page 12502]]

will also release SIP and transportation conformity policy guidance for 
the final release of MOVES, which among other issues will describe the 
grace period for using MOVES in regional and hot-spot conformity 
analyses.
    EPA has also dedicated significant resources to conducting research 
that will be used in the development of the Agency's future guidance 
for quantitative PM2.5 and PM10 hot-spot 
analyses, which would be available when states are able to begin using 
MOVES. This guidance will discuss how MOVES and dispersion models can 
be used to complete quantitative PM2.5 and PM10 
hot-spot analyses for the transportation projects specified in today's 
final rule.
Comment
    Several commenters agreed that stakeholders should be involved 
during the development of the future quantitative hot-spot modeling 
guidance. One commenter suggested that this guidance should be 
developed through a formal process similar to rulemakings. Another 
commenter recommended that EPA subject future hot-spot models and 
guidance to peer review.
Response
    EPA agrees that stakeholder input will be important in the guidance 
development process and intends to provide for such input, but has not 
yet determined exactly what that process will be. However, EPA does not 
intend to develop its future hot-spot modeling guidance through notice-
and-comment rulemaking, since this has not been our past practice for 
such guidance or even for motor vehicle emissions factor models like 
MOBILE6.2.

F. Suggestions for Future Guidance

Comment
    Several commenters had specific recommendations for items that 
should be included in EPA's future quantitative PM2.5 and 
PM10 hot-spot guidance. Examples of recommendations include:
     A screening procedure for reducing the number of 
quantitative analyses required;
     A list of potential project-level mitigation measures;
     Information on determining background contributions;
     A new assessment of re-entrained road dust and 
construction dust emission factors; and
     Information about idling emissions.
Response
    EPA will review these suggestions and others as part of the 
stakeholder process during the development of quantitative 
PM2.5 or PM10 hot-spot guidance.

VII. Categorical PM2.5 and PM10 Hot-spot Findings

A. Description of Final Rule

    EPA is finalizing its proposal allowing DOT to make categorical 
hot-spot findings \15\ for appropriate cases in PM2.5 and 
PM10 nonattainment and maintenance areas. A categorical hot-
spot finding would be made if there is appropriate modeling that shows 
that a particular category of highway or transit projects covered by 
Sec.  93.123(b)(1) will not cause or contribute to new or worsened 
local violations. Such findings have the potential to further 
streamline meeting the PM2.5 or PM10 hot-spot 
requirements, since no additional quantitative hot-spot modeling would 
be required to support a qualifying project's conformity 
determination.\16\ A project-level conformity determination relying on 
the categorical finding and meeting all other requirements is still 
required.
---------------------------------------------------------------------------

    \15\ In the December 2004 supplemental proposal and previous 
conformity rule, EPA used the term ``categorical conformity 
determination,'' but now believes this term is misleading. A 
conformity determination that meets all applicable requirements 
continues to be required for projects where a categorical hot-spot 
finding is relied upon. Consequently, the final rule uses the more 
appropriate terminology of ``categorical hot-spot finding.''
    \16\ Of course, categorical hot-spot findings would not be done 
for all other projects that are not an air quality concern since no 
hot-spot analysis--quantitative or qualitative--is required for 
those projects in PM2.5 and PM10 areas. These 
projects are already presumed to meet statutory requirements without 
any hot-spot analysis, as stipulated under Sec.  93.116(a) of the 
final rule.
---------------------------------------------------------------------------

    This final rule provides for FHWA and FTA to make categorical hot-
spot findings as appropriate for PM2.5 and PM10 
hot-spot analyses for projects listed in Sec.  93.123(b)(1) of today's 
final rule. See Section V. for more information about projects of air 
quality concern. EPA notes that the final rule clarifies and improves 
the existing conformity rule's flexibility for FTA to make categorical 
hot-spot findings in PM10 areas, which was originally 
promulgated in the conformity rule in November 24, 1993.\17\ See EPA's 
January 11, 1993 proposal (58 FR 3780) for further information.
---------------------------------------------------------------------------

    \17\ EPA notes that no categorical hot-spot findings have been 
made by FTA to date for transit projects in PM10 
nonattainment and maintenance areas.
---------------------------------------------------------------------------

    Modeling used to support a categorical hot-spot finding must be 
based on appropriate motor vehicle emissions factor models, dispersion 
models, and EPA's future quantitative hot-spot modeling guidance. As a 
result, categorical hot-spot findings will not be made prior to EPA's 
announcement in the Federal Register that quantitative PM2.5 
and PM10 hot-spot analyses are required (40 CFR 
93.123(b)(4)). Modeling used to support categorical hot-spot findings 
must consider the emissions produced from a category of projects based 
on project sizes, configurations, and activity levels. Modeling could 
also consider the emissions produced by a category of projects and the 
resulting impact on air quality under different circumstances.
    Categorical hot-spot findings could apply in a variety of 
situations where modeling shows that such projects will not cause or 
contribute to new or worsened violations. For instance, there may be 
cases where a categorical hot-spot finding could be made for a category 
of projects that would never cause a new air quality violation, worsen 
an existing violation or delay timely attainment in any 
PM2.5 or PM10 area.
    There may be other categories of projects that may be expected to 
meet Clean Air Act requirements without further hot-spot analysis if a 
given area has PM2.5 or PM10 air quality data 
which is significantly below the PM2.5 or PM10 
air quality standards. For example, a categorical hot-spot finding may 
be appropriate for a highway project with significant levels of diesel 
traffic in a PM10 maintenance area if that area is 
significantly below the PM10 standards. FHWA is currently 
examining, in consultation with EPA, whether certain categories of 
highway projects could qualify for a finding based on different levels 
of activity and air quality circumstances.
    EPA, with concurrence from DOT, is clarifying in this final rule 
the general process for making any categorical hot-spot findings. As 
stated above, this final rule does not affect the requirement for 
conformity determinations to be completed for all non-exempt projects 
in PM2.5 and PM10 areas. The modeling on which a 
categorical finding is based would serve to fulfill the quantitative 
hot-spot analysis requirement for qualifying projects. The modeled 
scenarios used by DOT to make categorical hot-spot findings would be 
derived through consultation and participation by EPA.
    Interagency consultation procedures for project-level conformity 
determinations must be followed (40 CFR 93.105). Any project-level 
conformity determination that relies on a categorical hot-spot finding 
would also be subject to the public involvement requirements of the 
NEPA process and the transportation

[[Page 12503]]

conformity rule (40 CFR 93.105(e)), during which commenters can address 
all appropriate issues relating to the categorical finding used in the 
conformity determination. Today's final rule does not create any new 
public participation requirements in project-level conformity 
determinations. See C. of this section for further details on the 
process for making categorical hot-spot findings.

B. Rationale and Response to Comments on Categorical Findings

1. Rationale
    EPA concludes that it is both appropriate and in compliance with 
the Clean Air Act to allow DOT to make categorical hot-spot findings 
with respect to categories of projects of air quality concern, where 
modeling shows that such projects will not cause or contribute to new 
or worsened air quality violations. As long as modeling shows that 
projects do not cause, contribute or worsen violations of the 
standards--either through an analysis of a category of projects or a 
hot-spot analysis for a single project--then statutory conformity 
requirements are met.
    As discussed in Section V., EPA finalized the criteria in Sec.  
93.123(b)(1) of this final rule for when quantitative PM2.5 
or PM10 hot-spot analyses are required, based on the best 
available information to date. Expanding the ability for DOT to make 
categorical hot-spot findings will allow future information to be taken 
into account in an expedited manner, so that quantitative 
PM2.5 and PM10 hot-spot analyses are only 
required for individual projects when necessary to protect public 
health and meet statutory requirements.
    Making hot-spot findings on a category basis will reduce the 
resource burden for state, regional and local agencies, and provide 
greater certainty and stability to the transportation planning process. 
A specific project-level conformity determination, including use of the 
categorical finding, will still be subject to applicable interagency 
consultation and public involvement as described in 40 CFR 93.105(e).
    Categorical hot-spot findings must be supported by credible 
modeling demonstrations showing that project categories will not cause 
or contribute to new or worsened violations of the air quality 
standards. Such modeling would need to be derived in consultation with 
EPA, and consistent with EPA's future PM2.5 and 
PM10 quantitative hot-spot modeling guidance.
2. Response to Comments
    EPA received numerous comments that supported the proposal, as well 
as a number of comments that did not.
Comment
    Several commenters supported the proposal to allow FHWA and FTA to 
make categorical hot-spot findings, if appropriate modeling shows that 
the Clean Air Act requirements are met without additional 
PM2.5 or PM10 hot-spot analyses. These commenters 
believed using Federal resources to make such findings would also 
reduce the resource burden for state, regional and local agencies, and 
provide greater certainty and stability to the transportation planning 
process.
Response
    EPA agrees and is taking final action consistent with the December 
2004 supplemental proposal and these comments.
Comment
    Other commenters objected to EPA's proposal because they believed 
that it would illegally delegate to FHWA and FTA the Agency's statutory 
authority to establish criteria and procedures for PM2.5 and 
PM10 transportation conformity determinations. These 
commenters believed that Congress explicitly required in the 1990 Clean 
Air Act Amendments that EPA, not DOT, promulgate the criteria and 
procedures for determining conformity, including the criteria and 
procedures for making categorical hot-spot findings. Many of these 
commenters stated that the proposal to expand the application of 
categorical hot-spot findings would cede EPA's authority not only to 
identify projects that do not require hot-spot analyses, but also to 
select the models or methods for determining whether emissions will 
cause or contribute to violations or delay timely attainment. These 
commenters believed that it is EPA's statutory responsibility to adopt 
criteria and procedures for any PM10 and PM2.5 
categorical hot-spot findings.
Response
    EPA disagrees with these comments. EPA does not believe that 
allowing DOT to make categorical hot-spot findings in any way delegates 
EPA's statutory obligation to establish criteria and procedures for 
PM2.5 and PM10 transportation conformity 
determinations. EPA, through its regulations and modeling guidance, 
continues to establish the criteria and procedures for PM2.5 
and PM10 transportation conformity determinations, including 
hot-spot analyses. These criteria are contained in Sec. Sec.  93.116 
and 93.123 of the conformity rule, including the revised provisions 
relating to categorical hot-spot findings. The conclusions by DOT in 
making categorical hot-spot findings that certain categories of 
projects will not cause or contribute to new or worsened violations, as 
well as the modeling supporting such findings, will be conducted 
consistent with EPA's conformity rule and future hot-spot modeling 
guidance discussed in Section VI. All aspects of a project-level 
conformity determination--including the reliance on a categorical hot-
spot finding--are subject to interagency consultation and public 
comment as described in 40 CFR 93.105(e).
    Furthermore, the authority to make categorical hot-spot findings 
does not enable DOT to identify projects that do not require hot-spot 
analyses at all. Rather, although hot-spot analyses are still required 
for all projects of air quality concern, this requirement can be 
satisfied by relying on modeling that concludes that certain categories 
of projects will not cause or contribute to new or worsened violations. 
Further, although EPA retains the authority to require hot-spot 
modeling in its conformity procedures and to specify appropriate models 
and methods in its future guidance, DOT has always had the authority to 
make project-level conformity determinations, including deciding 
whether a project meets the hot-spot analysis requirement through a 
categorical hot-spot finding or separate analysis.
Comment
    A few commenters stated that EPA's proposal also conflicts with 
Sec.  93.123(b)(4) of the conformity rule, which one commenter believes 
requires EPA (not DOT) to issue modeling guidance for quantitative 
PM2.5 and PM10 hot-spot analyses. A different 
commenter believed that the proposal conflicted with Sec.  93.123(b)(3) 
of the proposed conformity rule, which required interagency 
consultation be used to identify sites that require a hot-spot 
analysis. This commenter argued that the screening threshold or 
mechanism for identifying projects that do not require hot-spot 
analyses and selection of models or methods for hot-spot analyses need 
to be agreed upon under the interagency consultation process.
Response
    EPA disagrees with commenters. The final rule does not cede any of 
EPA's statutory authority to another Federal agency, and EPA will issue 
modeling

[[Page 12504]]

guidance for quantitative PM2.5 and PM10 hot-spot 
analyses. Furthermore, DOT will follow this guidance in conducting 
modeling to support any future categorical hot-spot findings.
    The final rule merely allows DOT to conduct such a single analysis 
for a category of projects rather than state and local agencies 
conducting a separate analysis for each project in such a category. DOT 
will consult with EPA on categorical hot-spot findings, and project-
level conformity determinations will be subject to interagency 
consultation and public involvement.
Comment
    Some commenters argued that the criteria and procedures for making 
categorical hot-spot findings, including modeling tools or other 
methods, must be established through a revision to the conformity rule 
or in 40 CFR part 51, Appendix W (Guideline on Air Quality Models). 
Such an approach, these commenters argued, would be consistent with 40 
CFR 93.123(a)(1) for quantitative CO hot-spot analyses, which requires 
such analyses to be based on ``applicable air quality models, data 
bases, and other requirements specified in 40 CFR part 51, Appendix W * 
* * unless different procedures developed through the interagency 
consultation process'' are approved by EPA. Finally, one of these 
commenters also specified that criteria for whether a project qualifies 
for a categorical hot-spot finding must be promulgated by EPA through 
notice-and-comment procedures prescribed by 42 U.S.C. 7506(c)(4)(A).
Response
    EPA does not agree that additional rulemaking is required or 
necessary to ensure that credible modeling is done to support 
categorical hot-spot findings. EPA has already requested comment in the 
development of today's final rule on: (1) The criteria for whether a 
project qualifies for a categorical hot-spot finding; and (2) the 
modeling that is used in such findings. The categorical hot-spot 
finding provisions in this final rule do not change the requirement for 
projects to not cause or contribute to PM2.5 or 
PM10 air quality violations under the Clean Air Act and 40 
CFR 93.116.
    EPA also notes that the conformity regulations have historically 
required PM10 hot-spot analyses without reference in its 
regulations to the air quality modeling requirements in Appendix W, 
since the ``Guideline'' includes only general information regarding 
PM2.5 and PM10 air quality modeling that would be 
applicable to such hot-spot analyses. The reference to Appendix W in 
the conformity regulation is due to a historical anomaly resulting from 
the fact that EPA had approved localized CO modeling techniques 
available at the time the original 1993 conformity rule was 
promulgated; however, no such techniques were approved for 
PM2.5 or PM10 hot-spot analyses at that time. EPA 
intends to recommend in its future hot-spot modeling guidance the use 
of air quality models, data bases, and other requirements that are 
consistent with SIP development for those provisions of Appendix W that 
apply. The public will have the opportunity to comment on this 
guidance. For all of these reasons, EPA believes that the final rule is 
consistent with both the Clean Air Act and the public input 
requirements of the Administrative Procedures Act.
Comment
    Some commenters questioned whether FHWA could adequately implement 
categorical hot-spot findings so that Clean Air Act requirements are 
met and protect public health. One commenter believed that FHWA has not 
properly implemented the current PM10 hot-spot requirements 
and FHWA's September 2001 guidance on PM10 qualitative hot-
spot analyses. Other commenters stated that EPA should maintain the 
statutory responsibility Congress transferred in the 1990 Clean Air Act 
Amendments, since EPA was given this authority due to DOT not 
sufficiently implementing the 1977 Clean Air Act conformity 
requirements.
Response
    This final rule requires that project-level conformity 
determinations include hot-spot analyses for projects of air quality 
concern in PM2.5 and PM10 areas. As stated above, 
EPA believes that it is retaining its authority to promulgate 
conformity criteria and procedures in providing for categorical hot-
spot findings in this final rule. It is true that qualitative 
PM10 hot-spot analyses have been required to this point, 
however this is due to the fact that credible quantitative hot-spot 
analyses cannot yet be performed. Finally, prior to the 1977 Clean Air 
Act Amendments, specific requirements on transportation conformity 
determinations including hot-spot analyses did not exist, thus this 
comment is not relevant to implementation of the current statutory 
provisions.
Comment
    One commenter believed that the proposed flexibility for FHWA and 
FTA to make categorical hot-spot findings should be extended to CO 
nonattainment and maintenance areas.
Response
    EPA did not propose expansion of the hot-spot flexibility to CO, 
and therefore can not take final action on such expansion at this time.
Comment
    One commenter who supported options that would define the need for 
PM2.5 hot-spot analyses through the SIP (i.e., Options 2 and 
B) opposed EPA's proposal for categorical hot-spot findings. This 
commenter believed that SIP revisions and consultation procedures could 
best address when categories of projects may be assumed to conform. In 
addition, this commenter stated that SIP revisions should be required 
to detail the types of projects where hot-spots are likely. The 
commenter also believed that quantitative analyses can be performed, 
where appropriate or where data is sufficient.
Response
    EPA concludes that the comment is no longer relevant to this 
rulemaking because the rule will not be defining the need for hot-spot 
analyses solely through the SIP process. Moreover, EPA reiterates that 
categorical hot-spot findings do not provide a determination that 
projects are assumed to conform. Rather, they are a conclusion based on 
modeling that a category of projects will not cause or contribute to 
NAAQS violations. A conformity determination is still required for all 
projects including a localized hot-spot analysis, which would be done 
by reference to the categorical finding. Finally, EPA notes that the 
Agency does not have authority under Clean Air Act section 176(c) to 
impose requirements on the content of SIP revisions relating to types 
of transportation projects that might produce hot-spots. States are 
free to consider this issue when developing PM2.5 attainment 
SIPs and to impose appropriate controls on transportation activities as 
necessary to demonstrate timely attainment.
Comment
    One commenter also recommended that any categorical hot-spot 
findings may need to be subject to a SIP finding should the SIP for an 
area determine that such a categorical finding is inappropriate under 
local conditions.
Response
    Categorical hot-spot findings are a conclusion by DOT based on 
appropriate modeling data that projects

[[Page 12505]]

of a certain type will not worsen air quality. Such findings would be 
used in future conformity determinations to satisfy the requirements of 
40 CFR 93.116 and 93.123 relating to localized PM2.5 and 
PM10 hot-spot analyses for projects of air quality concern. 
Should any SIP include a determination based on modeling that various 
categories of transportation projects would cause or contribute to 
violations of the standards, a categorical hot-spot finding could not 
be made, unless updated modeling and assumptions at a later date showed 
that such projects met statutory requirements.

C. Description of and Response to Comments on Process for Making 
Categorical Hot-spot Findings

1. Description of Process
    In its December 2004 supplemental proposal, EPA stated that it 
would work with DOT to provide additional guidance on making 
categorical hot-spot findings. EPA has consulted with DOT and 
categorical hot-spot findings will be made according to the following 
general process:
     FHWA and/or FTA, as applicable, will develop modeling, 
analyses, and documentation to support the categorical hot-spot 
finding. This would be done with early and comprehensive consultation 
and participation with EPA.
     FHWA and/or FTA will provide EPA an opportunity to review 
and comment on the complete categorical hot-spot finding documentation. 
Any comments would need to be resolved in a manner acceptable to EPA 
prior to issuance of the categorical hot-spot finding. Consultation 
with EPA on issue resolution would be documented.
     FHWA and/or FTA would make the final categorical hot-spot 
finding in a memorandum or letter, which would be posted on EPA's and 
DOT's respective conformity Web sites.
     Subsequently transportation projects that meet the 
criteria set forth in the categorical finding would reference that 
finding in their project-level conformity determination, which would be 
subject to interagency consultation and the public involvement 
requirements of the NEPA process and the conformity rule. The existing 
consultation and public involvement processes would be used to consider 
the categorical hot-spot finding in the context of a particular 
project.
2. Response to Comments
Comment
    Several commenters believed that EPA needed to further define the 
process for DOT to make categorical hot-spot findings for certain 
highway and transit projects. Commenters generally supported the 
proposal to have FHWA consult with EPA on categorical hot-spot 
findings. Several of these commenters stipulated that transportation 
and other conformity stakeholders should also be consulted when FHWA 
and EPA select the types of roadway and intersection projects covered 
and the modeling analyses used to support categorical hot-spot 
findings.
Response
    EPA has outlined the process for making categorical hot-spot 
findings in the preamble to the final rule as requested by commenters. 
DOT will consult with EPA in making the findings as requested by 
commenters. Project-level conformity determinations that rely on 
categorical hot-spot findings will remain subject to interagency 
consultation and public comment, as described in 40 CFR 93.105. As 
discussed under Section VI., EPA also plans to consider stakeholder 
input when preparing its future quantitative hot-spot modeling 
guidance; categorical hot-spot findings must be consistent with this 
guidance.
Comment
    One commenter believed that the proposed options for defining the 
need for PM2.5 hot-spot analyses through the SIP (i.e., 
Options 2 and B) could provide a full public process for categorical 
findings, since the public is involved in the development of SIPs.
Response
    As described in Sections III. and IV., EPA is not finalizing SIP-
based options for applying PM2.5 and PM10 hot-
spot analysis requirements because these options do not meet statutory 
conformity requirements. Furthermore, the conformity rule already 
provides an opportunity for project-level conformity determinations--
including those that rely on a categorical hot-spot finding--to be 
subject to interagency consultation and public comment. The final rule 
relies on these existing requirements.
Comment
    One commenter believed that EPA should make categorical hot-spot 
findings in consultation with FHWA. Another commenter suggested that 
the types of roadway and intersection projects covered by this 
flexibility be developed through EPA and DOT consultation.
Response
    It is not reasonable for EPA to make categorical hot-spot findings 
because EPA does not conduct the analyses to support conformity 
determinations. EPA promulgates criteria and procedures for making 
conformity determinations and then DOT makes the determinations 
consistent with those criteria. It is DOT that determines whether 
appropriate models from EPA's modeling guidance have been used in 
individual conformity determinations, and DOT that makes the final 
conformity determinations. Thus, it is proper for DOT to make all 
findings with respect to localized emission impacts, whether on an 
individual basis or categorically. EPA will participate with DOT on 
final categorical hot-spot findings and the modeling used to support 
such findings, as recommended by the commenter.
Comment
    One commenter believed that EPA and state and local air quality 
agencies must be required to concur on categorical hot-spot findings, 
at a minimum.
Response
    EPA does not believe it is necessary for EPA, state or local air 
agencies to concur in a categorical hot-spot finding. These findings 
are a preliminary step in DOT completion of a conformity determination. 
Neither EPA, states nor local air agencies concur in conformity 
determinations, which are made by DOT after interagency consultation 
with EPA, states and local agencies, as well as public involvement. 
Stakeholders retain all of the input authority they have under EPA and 
DOT rules with respect to conformity determinations in general. DOT is 
authorized to make conformity determinations under the Clean Air Act 
and the conformity regulations without explicit concurrence by other 
stakeholders. EPA concludes that it is appropriate for DOT to continue 
to do so consistent with the Clean Air Act after providing for 
interagency consultation and public comment, including those 
determinations that rely on a categorical hot-spot finding.
Comment
    One commenter was concerned that the proposal appeared to only 
apply to projects in which FHWA is participating. This commenter 
requested that language be added to the final rule to allow state 
transportation agencies to apply for the identified categorical hot-
spot finding for projects that require no Federal funds, if applicable.

[[Page 12506]]

Response
    EPA disagrees with this comment. Under the conformity regulations, 
only projects of air quality concern that require FHWA or FTA funding 
or approval are subject to the requirements of 40 CFR 93.116 and thus 
are required to have conformity determinations and localized hot-spot 
analyses. Therefore, state transportation agencies would have no need 
to conduct categorical hot-spot findings under the Federal conformity 
rule for regionally significant non-federal projects, as the commenter 
suggested. State transportation planners are certainly free to do 
localized hot-spot analyses as part of their transportation planning, 
but such analyses would not need to be conducted pursuant to the 
provisions of the Federal conformity regulations. As a result, EPA 
concludes that it is unnecessary to change the final rule in response 
to this comment.
Comment
    One commenter stated that categorical hot-spot findings should be 
left to the states working through their existing interagency 
consultation processes. This commenter believed that the analysis 
associated with such findings would more appropriately be performed at 
the state level due to variations between projects, emission control 
programs, meteorology, etc. at the local, state, regional and national 
level.
Response
    The final rule relies on the existing rule's interagency 
consultation provisions. Categorical findings are simply a way to 
streamline hot-spot analysis requirements in advance to support 
subsequent project-level conformity determinations that meet statutory 
and regulatory requirements. However, it is DOT, not states that make 
conformity determinations, and thus it is appropriate for DOT to also 
make categorical hot-spot findings that will support future project-
level conformity determinations. Project-level conformity 
determinations that rely on a categorical finding will remain subject 
to interagency consultation and public comment.
    As stated above, states will have input to any conformity 
determinations relying on a categorical hot-spot finding through the 
interagency consultation process on such determinations, and as such 
can provide input on the applicability of the categorical hot-spot 
finding analysis for a particular project's determination.

D. Stakeholder Suggestions for Eligible Projects and Future Federal 
Efforts

    In the December 2004 supplemental proposal, EPA specifically 
requested comment on the types of projects that might be appropriate 
for consideration under a categorical hot-spot finding. EPA received 
numerous helpful suggestions, which are summarized below. EPA has 
decided that it does not have sufficient information at this time to 
specify in the final rule which projects of air quality concern could 
receive future categorical hot-spot findings to streamline meeting the 
quantitative PM2.5 and PM10 hot-spot 
requirements. EPA is instead indicating here that findings could be 
made for any categories of projects addressed in Sec.  93.123(b)(1) for 
which the Federal agencies have adequate modeling to support 
demonstrating that such types of projects will not cause or contribute 
to any new or worsened localized violations.
    However, the suggestions submitted to the docket for this final 
rule will be considered in deciding where to begin to consider the 
development of the technical analyses necessary to support future 
categorical hot-spot findings, and could be considered by DOT in 
deciding whether to make a categorical hot-spot finding. The following 
are some of the suggestions received from commenters for categories of 
projects and different air quality circumstances that could be 
addressed by future findings:
    Types of projects:
     Projects that reduce congestion and idling. One commenter 
suggested that projects that eliminated bottlenecks and reduced 
congestion could be eligible since less congestion means less stop-and-
go traffic, and hence would reduce PM even with a significant increase 
in diesel traffic. This commenter believed that analyses could be 
conducted to quantify this tradeoff so as to determine if and when a 
congestion-reducing project might still trigger hot-spot concerns.
    Types of air quality circumstances:
     Projects in locations with significant margins of safety 
relative to the applicable standards.
     Projects in portions of the nonattainment area where 
current monitoring data and forecasted concentrations show no violation 
of the PM2.5 standards.
    FHWA has recently dedicated resources to begin considering what 
projects could qualify for future categorical hot-spot findings, in 
consultation with EPA. This ongoing effort is focused on evaluating the 
impacts of individual types of projects and air quality circumstances, 
for example the NAAQS level at different kinds of project locations. 
This and other future work may eventually lead to development of 
categorical hot-spot findings through the process identified above, and 
this work will be consistent with EPA's future quantitative 
PM2.5 and PM10 modeling guidance and any models 
that are appropriate for use by state and local implementers in 
individual project analyses.

VIII. Minor Change for Exempt Projects Regarding Compliance With 
PM2.5 SIP Control Measures

    EPA proposed a minor regulatory change in the December 2004 
supplemental proposal in regard to compliance with PM2.5 SIP 
control measures. EPA is finalizing today a small change to the 
footnote at the bottom of Table 2 in 40 CFR 93.126. Section 93.126 is 
titled, ``Exempt projects'' and Table 2 lists these projects under 
several different headings. Projects listed in the table are exempt 
from the requirement to determine conformity, and may proceed even in 
the absence of a conforming transportation plan and TIP.
    Today's final rule adds ``and PM2.5'' after 
``PM10'' in the footnote at the bottom of Table 2. 
Currently, the footnote reads, ``Note: In PM10 nonattainment 
or maintenance areas, such projects are exempt only if they are in 
compliance with control measures in the applicable implementation 
plan.'' However, PM2.5 areas also need to be included in 
this note to make Sec.  93.126 consistent with 40 CFR 93.117. In the 
July 1, 2004 final rule, EPA updated Sec.  93.117, which discusses 
compliance with SIP control measures to also cover PM2.5 
areas. EPA should have updated the footnote in Sec.  93.126 in the July 
1, 2004 rule; we are correcting this oversight in today's action. With 
this change, projects on the exempt list in Sec.  93.126 would be 
exempt in a PM2.5 area only if they are in compliance with 
control measures in the applicable SIP.

IX. How Does Today's Final Rule Affect Conformity SIPs?

A. PM2.5 Areas and PM10 Areas Without Approved 
Conformity SIPs

    All provisions in today's final rule relating to PM2.5 
hot-spots apply immediately in all PM2.5 nonattainment and 
maintenance areas because no prior conformity rules (or approved 
conformity SIPs) address these PM2.5 hot-spot requirements. 
PM10 areas that do not have approved conformity SIPs will be 
able to use immediately all of the conformity amendments related to

[[Page 12507]]

PM10 that are included in today's final rule.

B. PM10 Areas With Approved Conformity SIPs

    In some areas, EPA has already approved conformity SIPs that 
include PM10 hot-spot provisions from previous conformity 
rulemakings that EPA is revising in today's final rule. In these areas, 
the Clean Air Act prohibits today's Federal rule amendments from 
superceding the previously approved state rules. Therefore, the 
PM10 hot-spot rule amendments in today's final rule--
including the new Sec. Sec.  93.116(a) and 93.123(b)--will only be 
effective in areas with approved conformity SIPs that include related 
rule provisions when the state either:
     Withdraws the existing provisions from its approved 
conformity SIP and EPA approves the withdrawal because, as discussed 
below, the Clean Air Act has been amended to streamline conformity SIP 
requirements, or
     Includes the revised PM10 hot-spot requirements 
in a SIP revision and EPA approves that SIP revision.
    EPA has no authority to disregard this statutory requirement for 
those portions of today's final rule.
    The Safe, Accountable, Flexible, Efficient Transportation Equity 
Act: A Legacy for Users (SAFETEA-LU) (Pub. L. 109-59) amended the 
conformity SIP requirements contained in Clean Air Act section 
176(c)(4). Prior to SAFETEA-LU being signed into law, Clean Air Act 
section 176(c)(4)(C) required states to submit revisions to their SIPs 
to reflect all of the Federal criteria and procedures for determining 
conformity.
    SAFETEA-LU section 6011(f)(4) amends Clean Air Act section 
176(c)(4) so that states are now required to address in their 
conformity SIPs only the three sections on the Federal conformity rule 
that are required to be tailored, which are:
     Section 93.105 which addresses consultation procedures;
     Section 93.122(a)(4)(ii) which addresses written 
commitments to control measures that are not included in an MPO's 
transportation plan and TIP which must be obtained prior to a 
conformity determination and the requirement that such commitments must 
be fulfilled; and
     Section 93.125(c) which addresses written commitments to 
mitigation measures which must be obtained prior to a project-level 
conformity determination, and the requirement that project sponsors 
must comply with such commitments.
    SAFETEA-LU eliminates the previous statutory conformity rule 
requirement to also include all other sections of the Federal rule. 
Therefore, states with approved conformity SIPs may decide to withdraw 
the sections which they are no longer required to include in their 
SIPs. EPA will process these SIP revisions as expeditiously as possible 
through flexible administrative techniques such as parallel processing 
and direct final rulemaking, since these provisions are no longer 
required by the Clean Air Act.

C. No New Conformity SIP Deadline Is Created by Final Rule

    EPA believes that no new conformity SIP deadline is triggered by 
this final rule in any PM2.5 or PM10 
nonattainment or maintenance area. However, PM10 areas with 
approved conformity SIPs may decide to update their SIPs to reflect the 
final rule's PM10 hot-spot provisions, as described above.
    With respect to the provisions that now must be included in SIPs 
under SAFETEA-LU, today's final rule does not make any changes to 
either Sec.  93.122(a)(4)(ii) or Sec.  93.125(c). However, today's 
final rule does amend Sec.  93.105 by deleting Sec.  93.105(c)(1)(v) 
from the conformity rule. Section 93.105(c)(1)(v) required areas to 
consult on determining which projects in PM10 nonattainment 
and maintenance areas are located at sites which have vehicle and 
roadway emission and dispersion characteristics which are essentially 
identical to those at sites which have violations verified by 
monitoring, and therefore require a quantitative PM10 hot-
spot analysis. EPA deleted this provision for reasons described in 
Section V. of today's action.
    EPA believes the deletion of Sec.  93.105(c)(1)(v) is not 
significant enough by itself to warrant any states being required to 
update their conformity SIPs within 12 months of the publication of 
today's final rule given that states can continue to effectively 
implement their existing conformity SIPs with this provision remaining 
in place. Although as noted above, a PM10 area with an 
approved SIP may decide to update its SIP in order to use the final 
rule's PM10 hot-spot provisions.
    EPA and DOT have provided guidance on implementing the conformity 
SIP provisions contained in SAFETEA-LU. This guidance is posted on 
EPA's transportation conformity Web site listed in Section I.B.2. of 
today's final rule, and is also available on DOT's Web site at: http://www.fhwa.dot.gov/environment/conformity/sec6011guidmemo.htm.

X. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    Under Executive Order 12866, (58 FR 51735; October 4, 1993) the 
Agency must determine whether the regulatory action is ``significant'' 
and therefore subject to review and the requirements of the Executive 
Order. The Order defines significant ``regulatory action'' as one that 
is likely to result in a rule that may:
    (1) Have an annual effect on the economy of $100 million or more, 
or otherwise adversely affect in a material way the economy, a sector 
of the economy, productivity, competition, jobs, the environment, 
public health or safety, or State, local, or tribal governments or 
communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof;
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    Under the terms of Executive Order 12866, it has been determined 
that amendments to this rule that are related to conformity under the 
current PM2.5 air quality standards are a ``significant 
regulatory action.'' As such, this action was submitted to OMB for 
Executive Order 12866 review. Changes made in response to OMB 
suggestions or recommendations are documented in the public record.

B. Paperwork Reduction Act

    OMB has approved the information collection requirements related to 
PM2.5 contained in this rule for PM2.5 areas 
under the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et 
seq. and has assigned OMB control number 2060-0561.
    Transportation conformity determinations are required under Clean 
Air Act section 176(c) (42 U.S.C. 7506(c)) to ensure that federally 
supported highway and transit project activities are consistent with 
(``conform to'') the purpose of the SIP. Conformity to the purpose of 
the SIP means that transportation activities will not cause or 
contribute to new air quality violations, worsen existing violations, 
or delay timely attainment of the relevant air quality standards. 
Transportation conformity applies under EPA's conformity regulations at 
40 CFR 51.390 and 40 CFR part 93 to areas that are

[[Page 12508]]

designated nonattainment and those redesignated to attainment after 
1990 (``maintenance areas'' with SIPs developed under Clean Air Act 
section 175A) for transportation-source criteria pollutants. The Clean 
Air Act gives EPA the statutory authority to establish the criteria and 
procedures for determining whether transportation activities conform to 
the SIP.
    Provisions in today's final rule that are related to conformity 
requirements in existing PM10 nonattainment and maintenance 
areas do not impose any new information collection requirements from 
EPA that require approval by OMB under the Paperwork Reduction Act, 44 
U.S.C. 3501 et seq. The information collection requirements of 
revisions in today's action for existing PM10 areas are 
covered under the DOT information collection request (ICR) entitled, 
``Metropolitan and Statewide Transportation Planning,'' with the OMB 
control number of 2132-0529.
    EPA provided two opportunities for public comment on the 
incremental burden estimates for transportation conformity 
determinations under the new 8-hour ozone and PM2.5 
standards. EPA received comments on both the initial burden estimates 
provided in the November 5, 2003 proposal (68 FR 62719-62720) and on 
the revised estimates in the January 2004 ICR (69 FR 336). EPA 
responded to all of these comments in the ICR that has been approved by 
OMB. The approved ICR addresses all aspects of the conformity rule as 
it applies to the new 8-hour ozone and PM2.5 air quality 
standards. The approved ICR accounts for PM2.5 hot-spot 
burden associated with the most intensive of the proposed options 
(i.e., requiring PM2.5 hot-spot analyses for all projects in 
PM2.5 areas at all times). Consequently, since this final 
rule only requires hot-spot analyses for a subset of all types of 
projects (i.e., projects of air quality concern), the approved ICR 
addresses--and even overestimates--the actual PM2.5 hot-spot 
burden that will occur under this final rule.
    Burden means the total time, effort, or financial resources 
expended by persons to generate, maintain, retain, disclose or provide 
information to or for a Federal agency. This includes the time needed 
to review instructions; develop, acquire, install and utilize 
technology and systems for the purposes of collecting, validating, and 
verifying information, processing and maintaining information, and 
disclosing and providing information; adjust the existing ways to 
comply with any previously applicable instructions and requirements; 
train personnel to be able to respond to a collection of information; 
search data sources; complete and review the collection of information; 
and, transmit or otherwise disclose the information.
    An agency may not conduct or sponsor, and a person is not required 
to respond to a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations in 40 CFR are listed in 40 CFR part 9. In addition, EPA has 
amended the table in 40 CFR part 9 of currently approved OMB control 
numbers for various regulations to list the regulatory citations for 
the information requirements contained in this final rule.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act, as amended by the Small Business 
Regulatory Enforcement Fairness Act of 1996, requires the Agency to 
conduct a regulatory flexibility analysis of any significant impact a 
rule will have on a substantial number of small entities. Small 
entities include small businesses, small not-for-profit organizations 
and small government jurisdictions.
    For purposes of assessing the impacts of today's final rule on 
small entities, small entity is defined as: (1) A small business as 
defined by the Small Business Administration's (SBA) regulations at 13 
CFR 121.201; (2) a small governmental jurisdiction that is a government 
of a city, county, town, school district or special district with a 
population of less than 50,000; and (3) a small organization that is 
any not-for-profit enterprise which is independently owned and operated 
and is not dominant in its field.
    After considering the economic impacts of today's final rule on 
small entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. This 
regulation directly affects Federal agencies, state departments of 
transportation and metropolitan planning organizations that, by 
definition, are designated under federal transportation laws only for 
metropolitan areas with a population of at least 50,000. These 
organizations do not constitute small entities within the meaning of 
the Regulatory Flexibility Act.

D. Unfunded Mandates Reform Act

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 104-4, establishes requirements for federal agencies to assess the 
effects of their regulatory actions on state, local, and tribal 
governments and the private sector. Under section 202 of the UMRA, EPA 
generally must prepare a written statement, including a cost-benefit 
analysis, for proposed and final rules with ``Federal mandates'' that 
may result in expenditures to State, local, and tribal governments, in 
the aggregate, or to the private sector, of $100 million or more in any 
one year. Before promulgating an EPA rule for which a written statement 
is needed, section 205 of the UMRA generally requires EPA to identify 
and consider a reasonable number of regulatory alternatives and adopt 
the least costly, most cost-effective or least burdensome alternative 
that achieves the objectives of the rule. The provisions of section 205 
do not apply when they are inconsistent with applicable law. Moreover, 
section 205 allows EPA to adopt an alternative other than the least 
costly, most cost-effective or least burdensome alternative if the 
Administrator publishes with the final rule an explanation why that 
alternative was not adopted. Before EPA establishes any regulatory 
requirements that may significantly or uniquely affect small 
governments, including tribal governments, it must have developed under 
section 203 of the UMRA a small government agency plan. The plan must 
provide for notifying potentially affected small governments, enabling 
officials of affected small governments to have meaningful and timely 
input in the development of EPA regulatory proposals with significant 
Federal intergovernmental mandates, and informing, educating, and 
advising small governments on compliance with the regulatory 
requirements.
    EPA has determined that this final rule itself does not contain a 
Federal mandate that may result in expenditures of $100 million or more 
for State, local, and tribal governments, in the aggregate, or the 
private sector in any one year. The primary purpose of this final rule 
is to determine requirements for hot-spot analyses in PM2.5 
and PM10 nonattainment and maintenance areas. Clean Air Act 
section 176(c)(5) requires the applicability of conformity to such 
areas as a matter of law one year after new nonattainment designations. 
Thus, although this rule explains how these analyses should be 
conducted, it merely implements already established law that imposes 
conformity requirements and does not itself impose requirements that 
may result in expenditures of $100 million or more in any year. Thus, 
today's final rule is not subject to the requirements of sections 202 
and 205 of the UMRA and EPA has not prepared a statement with respect 
to budgetary impacts.

[[Page 12509]]

E. Executive Order 13132: Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include regulations that have ``substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government.''
    This final rule does not have federalism implications. It will not 
have substantial direct effects on the States, on the relationship 
between the national government and the States, or on the distribution 
of power and responsibilities among the various levels of government, 
as specified in Executive Order 13132. The Clean Air Act requires 
conformity to apply in certain nonattainment and maintenance areas as a 
matter of law, and this final action merely establishes and revises 
procedures for transportation planning entities in subject areas to 
follow in meeting their existing statutory obligations. Thus, Executive 
Order 13132 does not apply to this final rule.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    Executive Order 13175: ``Consultation and Coordination with Indian 
Tribal Governments'' (65 FR 67249, November 6, 2000) requires EPA to 
develop an accountable process to ensure ``meaningful and timely input 
by tribal officials in the development of regulatory policies that have 
tribal implications.'' ``Policies that have tribal implications'' is 
defined in the Executive Order to include regulations that have 
``substantial direct effects on one or more Indian tribes, on the 
relationship between the Federal government and the Indian tribes, or 
on the distribution of power and responsibilities between the Federal 
government and Indian tribes.''
    Today's amendments to the conformity rule do not significantly or 
uniquely affect the communities of Indian tribal governments, as the 
Clean Air Act requires transportation conformity to apply in any area 
that is designated nonattainment or maintenance by EPA. This final rule 
incorporates into the conformity rule provisions addressing newly 
designated PM2.5 nonattainment and maintenance areas subject 
to conformity requirements under the Clean Air Act that would not have 
substantial direct effects on tribal governments, on the relationship 
between the Federal government and Indian tribes, or on the 
distribution of power and responsibilities between the Federal 
government and Indian tribes, as specified in Executive Order 13175, 
since these rules merely establish procedures for implementing the 
statutory mandates of the conformity provisions which already apply 
under the Clean Air Act as a matter of law. Accordingly, the 
requirements of Executive Order 13175 are not applicable to this final 
rule.

G. Executive Order 13045: Protection of Children From Environmental 
Health and Safety Risks

    Executive Order 13045: ``Protection of Children from Environmental 
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies 
to any rule that: (1) Is determined to be ``economically significant'' 
as defined under Executive Order 12866, and (2) concerns an 
environmental health or safety risk that EPA has reason to believe may 
have a disproportionate effect on children. If the regulatory action 
meets both criteria, the Agency must evaluate the environmental health 
or safety effects of the planned rule on children, and explain why the 
planned regulation is preferable to other potentially effective and 
reasonably feasible alternatives considered by the Agency.
    This final is not subject to Executive Order 13045 because it is 
not economically significant within the meaning of Executive Order 
12866 and does not involve the consideration of relative environmental 
health or safety risks to children.

H. Executive Order 13211: Actions That Significantly Affect Energy 
Supply, Distribution or Use

    This final rule is not subject to Executive Order 13211, ``Action 
Concerning Regulations That Significantly Affect Energy Supply, 
Distribution, or Use'' (66 FR 28355; May 22, 2001) because it will not 
have a significant adverse effect on the supply, distribution, or use 
of energy.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (``NTTAA''), Public Law No. 104-113, section 12(d) (15 
U.S.C. 272 note) directs EPA to use voluntary consensus standards in 
its regulatory activities unless to do so would be inconsistent with 
applicable law or otherwise impractical. Voluntary consensus standards 
are technical standards (e.g., materials specifications, test methods, 
sampling procedures, and business practices) that are developed or 
adopted by voluntary consensus standards bodies. The NTTAA directs EPA 
to provide Congress, through OMB, explanations when the Agency decides 
not to use available and applicable voluntary consensus standards.
    This final rule does not involve technical standards. Therefore, 
the use of voluntary consensus standards does not apply to this final 
rule.

J. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. The EPA will submit this final rule and other required 
information to the U.S. Senate, the U.S. House of Representatives, and 
the Comptroller General of the United States prior to publication of 
the final rule in the Federal Register. This rule is not a ``major 
rule'' as defined by 5 U.S.C. 804(2).
    This final rule is effective April 5, 2006 for good cause found as 
explained in this rule.

K. Petitions for Judicial Review

    Under Clean Air Act section 307(b)(1), petitions for judicial 
review of this action must be filed in the United States Court of 
Appeals for the appropriate circuit by May 9, 2006. Filing a petition 
for reconsideration by the Administrator of this final rule does not 
affect the finality of this rule for the purposes of judicial review, 
nor does it extend the time within which a petition for judicial review 
may be filed, and shall not postpone the effectiveness of such a rule 
or action. This action may not be challenged later in proceedings to 
enforce its requirements. (See section 307(b)(2) of the Administrative 
Procedures Act.)

L. Determination Under Section 307(d)

    Pursuant to Clean Air Act section 307(d)(1)(U), the Administrator 
determines that this action is subject to the provisions of section 
307(d). Section 307(d)(1)(U) provides that the provisions of section 
307(d) apply to ``such other actions as the Administrator may 
determine.'' While the Administrator did not make this determination 
earlier, the Administrator

[[Page 12510]]

believes that all of the procedural requirements, e.g., docketing, 
hearing and comment periods, of section 307(d) have been complied with 
during the course of this rulemaking.

List of Subjects in 40 CFR Part 93

    Environmental protection, Administrative practice and procedure, 
Air pollution control, Carbon monoxide, Intergovernmental relations, 
Nitrogen dioxide, Ozone, Particulate matter, Transportation, Volatile 
organic compounds.

    Dated: February 23, 2006.
Stephen L. Johnson,
Administrator.


0
For the reasons set out in the preamble, 40 CFR part 93 is amended as 
follows:

PART 93--[AMENDED]

0
1. The authority citation for part 93 continues to read as follows:

    Authority: 42 U.S.C. 7401-7671q.


Sec.  93.101  [Amended]

0
2. Section 93.101 is amended in the first sentence of the definition 
for ``Hot-spot analysis'' by removing ``CO and PM10'' and 
adding in its place ``CO, PM10, and/or PM2.5''.


Sec.  93.105  [Amended]

0
3. Section 93.105 is amended by removing paragraph (c)(1)(v) and 
redesignating paragraphs (c)(1)(vi) and (vii) as paragraphs (c)(1)(v) 
and (vi).

0
4. Section 93.109 is amended as follows:
0
a. In Table 1 of paragraph (b), revising both entries for ``Sec.  
93.116'';
0
b. By redesignating paragraphs (i)(1) and (2) as paragraphs (i)(2) and 
(3) and adding new paragraph (i)(1);
0
c. In paragraph (j) by removing ``CO and PM10'' and adding 
in its place ``CO, PM10, and PM2.5'';
0
d. In paragraph (k) by removing ``CO and PM10'' and adding 
in its place ``CO, PM10, and PM2.5''; and
0
e. In paragraph (l)(1) by removing ``CO and PM10'' and 
adding in its place ``CO, PM10, and PM2.5''.


Sec.  93.109  Criteria and procedures for determining conformity of 
transportation plans, programs, and projects: General.

* * * * *
    (b) * * *

                      Table 1.--Conformity Criteria
------------------------------------------------------------------------
 
------------------------------------------------------------------------
 
                                * * * * *
Sec.   93.116.............................  CO, PM10, and PM2.5 hot-
                                             spots.
 
                                * * * * *
Sec.   93.116.............................  CO, PM10, and PM2.5 hot-
                                             spots.
 
                                * * * * *
------------------------------------------------------------------------

* * * * *
    (i) * * *
    (1) FHWA/FTA projects in PM2.5 nonattainment or 
maintenance areas must satisfy the appropriate hot-spot test required 
by Sec.  93.116(a).
* * * * *

0
5. In Sec.  93.116, the section heading and paragraph (a) are revised 
to read as follows:


Sec.  93.116  Criteria and procedures: Localized CO, PM10, 
and PM2.5 violations (hot-spots).

    (a) This paragraph applies at all times. The FHWA/FTA project must 
not cause or contribute to any new localized CO, PM10, and/
or PM2.5 violations or increase the frequency or severity of 
any existing CO, PM10, and/or PM2.5 violations in 
CO, PM10, and PM2.5 nonattainment and maintenance 
areas. This criterion is satisfied without a hot-spot analysis in 
PM10 and PM2.5 nonattainment and maintenance 
areas for FHWA/FTA projects that are not identified in Sec.  
93.123(b)(1). This criterion is satisfied for all other FHWA/FTA 
projects in CO, PM10 and PM2.5 nonattainment and 
maintenance areas if it is demonstrated that during the time frame of 
the transportation plan (or regional emissions analysis) no new local 
violations will be created and the severity or number of existing 
violations will not be increased as a result of the project. The 
demonstration must be performed according to the consultation 
requirements of Sec.  93.105(c)(1)(i) and the methodology requirements 
of Sec.  93.123.
* * * * *

0
6. Section 93.123 is amended as follows:
0
a. Revising the section heading;
0
b. Amending the first sentence in paragraph (a)(1) introductory text by 
removing ``CO and PM10'' and adding in its place ``CO, 
PM10, and PM2.5'';
0
c. Amending paragraph (b) by:
0
i. Revising the paragraph heading;
0
ii. Revising paragraphs (b)(1)(i), (ii) and (iii), and adding new 
paragraphs (b)(1)(iv) and (v); and
0
iii. Revising paragraphs (b)(2) and (b)(3);
0
d. Amending paragraph (c)(4) by removing ``PM10 or CO'' in 
the first sentence and adding in its place ``CO, PM10, or 
PM2.5''; and
0
e. Amending paragraph (c)(5) by removing ``CO and PM10'' in 
the first sentence and adding in its place ``CO, PM10, and 
PM2.5''.


Sec.  93.123  Procedures for determining localized CO, PM10, 
and PM2.5 concentrations (hot-spot analysis).

* * * * *
    (b) PM10 and PM2.5 hot-spot analyses. (1) * * 
*
    (i) New or expanded highway projects that have a significant number 
of or significant increase in diesel vehicles;
    (ii) Projects affecting intersections that are at Level-of-Service 
D, E, or F with a significant number of diesel vehicles, or those that 
will change to Level-of-Service D, E, or F because of increased traffic 
volumes from a significant number of diesel vehicles related to the 
project;
    (iii) New bus and rail terminals and transfer points that have a 
significant number of diesel vehicles congregating at a single 
location;
    (iv) Expanded bus and rail terminals and transfer points that 
significantly increase the number of diesel vehicles congregating at a 
single location; and
    (v) Projects in or affecting locations, areas, or categories of 
sites which are identified in the PM10 or PM2.5 
applicable implementation plan or implementation plan submission, as 
appropriate, as sites of violation or possible violation.
    (2) Where quantitative analysis methods are not available, the 
demonstration required by Sec.  93.116 for projects described in 
paragraph (b)(1) of this section must be based on a qualitative 
consideration of local factors.
    (3) DOT, in consultation with EPA, may also choose to make a 
categorical hot-spot finding that Sec.  93.116 is met without further 
hot-spot analysis for any project described in paragraph (b)(1) of this 
section based on appropriate modeling. DOT, in consultation with EPA, 
may also consider the current air quality circumstances of a given 
PM2.5 or PM10 nonattainment or maintenance area 
in categorical hot-spot findings for applicable FHWA or FTA projects.
* * * * *


Sec.  93.125  [Amended]

0
7. Section 93.125(a) is amended by removing ``PM10 or CO'' 
in the first sentence and adding in its place ``CO, PM10, or 
PM2.5''.


Sec.  93.126  [Amended]

0
8. Section 93.126 is amended in footnote 1 by removing 
``PM10'' and adding in its place ``PM10 and 
PM2.5''.

[[Page 12511]]

Sec.  93.127  [Amended]

0
9. Section 93.127 is amended as follows:
0
a. Amending the second sentence by removing ``or PM10''.
0
b. Adding a new sentence after the second sentence to read as follows: 
``The local effects of projects with respect to PM10 and 
PM2.5 concentrations must be considered and a hot-spot 
analysis performed prior to making a project-level conformity 
determination, if a project in Table 3 also meets the criteria in Sec.  
93.123(b)(1).''

[FR Doc. 06-2178 Filed 3-6-06; 9:21 am]
BILLING CODE 6560-50-P