[Federal Register: March 10, 2006 (Volume 71, Number 47)]
[Rules and Regulations]               
[Page 12467-12511]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr10mr06-14]                         


[[Page 12467]]

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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


[[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: patulski.meg@epa.gov; 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: kapichak.rudolph@epa.gov.

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.

[[Page 12471]]

    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

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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

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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

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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 co