Page 1 of 58

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 93

[EPA-HQ-OAR-2009-0128; FRL-XXXX-X]

RIN 2060-AP57

Transportation Conformity Rule Restructuring Amendments

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

SUMMARY: EPA is amending the transportation conformity 

rule to finalize provisions that were proposed on August 

13, 2010. These amendments restructure several sections of 

the transportation conformity rule so that they apply to 

any new or revised National Ambient Air Quality Standards. 

EPA is also finalizing several clarifications to improve 

implementation of the rule. EPA is not taking a final 

action at this time on the proposal that areas analyze a 

near-term analysis year when using the budget test.

The Clean Air Act requires federally supported 

transportation plans, transportation improvement programs, 

and projects to be consistent with (conform to) the purpose 

of the state air quality implementation plan. EPA 

consulted with the U.S. Department of Transportation and 

they concur in the development of this final rule.
Page 2 of 58

DATES: This final rule is effective on [insert date 30 

days after publication in the Federal Register]. 

ADDRESSES: EPA has established a docket for this action 

under Docket ID No. EPA-HQ-OAR-2009-0128. All documents in 

the docket are listed in the www.regulations.gov index. 

Although listed in the index, some information may not be 

publicly available, e.g., CBI or other information whose 

disclosure is restricted by statute. Certain other 

material, such as copyrighted material, will be publicly 

available only in hard copy. Publicly available docket 

materials are available either electronically in 

www.regulations.gov or in hard copy at the Air and 

Radiation Docket, EPA/DC, EPA West, Room 3334, 1301 

Constitution Ave., NW, Washington, DC. The Public Reading 

Room is open from 8:30 a.m. to 4:30 p.m., Monday through 

Friday, excluding legal holidays. The telephone number for 

the Public Reading Room is (202) 566-1744 and the telephone 

number for the Air and Radiation Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Patty Klavon, 

Transportation and Regional Programs Division, 

Environmental Protection Agency, 2000 Traverwood Drive, Ann 

Arbor, MI 48105, e-mail address: klavon.patty@epa.gov, 

telephone number: (734) 214-4476, fax number: (734) 214-

4052; or Laura Berry, Transportation and Regional Programs 
Page 3 of 58

Division, Environmental Protection Agency, 2000 Traverwood 

Drive, Ann Arbor, MI 48105, e-mail address: 

berry.laura@epa.gov, telephone number: (734) 214-4858, fax 

number: (734) 214-4052.

SUPPLEMENTARY INFORMATION: 

The contents of this preamble are listed in the following 

outline:

I. General Information 

II. Background on the Transportation Conformity Rule

III. Restructure of Section 93.109 -- Tests of 

Conformity for Transportation Plans, TIPs, and 

Projects -- and Changes to Related Sections

IV. Additional Option for Areas That Qualify for 

EPA’s Clean Data Regulations or Policies

V. Restructure of the Baseline Year Test for 

Existing NAAQS and Baseline Year Test for Future 

NAAQS

VI. How Do These Amendments Affect Conformity SIPs?

VII. 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 
Page 4 of 58

U.S.C. or title 49 U.S.C. Chapter 53. Regulated categories 

and entities affected by today’s action include:

Category Examples of regulated entities

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)).

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 transportation 

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 Do I Get Copies of This Document?
Page 5 of 58

1. Docket

EPA has established an official public docket for this 

action under Docket ID No. EPA-HQ-OAR-2009-0128. You can 

get a paper copy of this Federal Register document, as well 

as the documents specifically referenced in this action, 

any public comments received, and other information related 

to this action at the official public docket. See the 

ADDRESSES section for its location. 

2. Electronic Access 

You may access this Federal Register document 

electronically through EPA’s Transportation Conformity 

website at 

www.epa.gov/otaq/stateresources/transconf/index.htm. An 

electronic version of the official public docket is also 

available through www.regulations.gov. You may use 

www.regulations.gov 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 electronically. Once in the system, 

select “search,” then enter the appropriate docket 

identification number. 

Certain types of information will not be placed in the 

electronic public docket. Information claimed as CBI and 

other information for which disclosure is restricted by 
Page 6 of 58

statute is not available for public viewing in the 

electronic public docket. EPA’s policy is that copyrighted 

material will not be placed in the electronic public docket 

but will be available only in printed, paper form in the 

official public docket. 

To the extent feasible, publicly available docket 

materials will be made available in the electronic public 

docket. When a document is selected from the index list in 

EPA Dockets, the system will identify whether the document 

is available for viewing in the electronic public docket. 

Although not all docket materials may be available 

electronically, you may still access any of the publicly 

available docket materials through the docket facility 

identified in the ADDRESSES section. EPA intends to 

provide electronic access in the future to all of the 

publicly available docket materials through the electronic 

public docket.

For additional information about the electronic public 

docket, visit the EPA Docket Center homepage at 

www.epa.gov/epahome/dockets.htm.

II. Background on the Transportation Conformity Rule 

A. What Is Transportation Conformity?

Transportation conformity is required under Clean Air 

Act (CAA) section 176(c) (42 U.S.C. 7506(c)) to ensure that 
Page 7 of 58

transportation plans, transportation improvement programs 

(TIPs) and federally supported highway and transit projects 

are consistent with (conform to) the purpose of the state 

air quality implementation plan (SIP). Conformity to the 

purpose of the SIP means that transportation activities 

will not cause or contribute to new air quality violations, 

worsen existing violations, or delay timely attainment or 

achievement of the relevant National Ambient Air Quality 

Standards (NAAQS) and interim emission reductions or 

milestones. Transportation conformity (hereafter, 

“conformity”) applies to areas that are designated 

nonattainment, and those areas redesignated to attainment 

after 1990 (“maintenance areas”) for transportation-related 

criteria pollutants: carbon monoxide (CO), ozone, nitrogen 

dioxide (NO2) and particulate matter (PM2.5 and PM10).1 

EPA’s conformity rule (40 CFR Parts 51.390 and 93 

Subpart A) establishes the criteria and procedures for 

determining whether transportation activities conform to 

the SIP. EPA first promulgated the conformity rule on 

November 24, 1993 (58 FR 62188), and subsequently published 

several other amendments. DOT is EPA’s federal partner in 

 

1

40 CFR 93.102(b)(1) defines PM2.5 and PM10 as particles with an 

aerodynamic diameter less than or equal to a nominal 2.5 and 10 

micrometers, respectively.
Page 8 of 58

implementing the conformity regulation. EPA consulted with 

the U.S. Department of Transportation (DOT), and they 

concur on this final rule.

B. Why Are We Issuing This Final Rule?

EPA is amending the conformity rule so that its 

requirements will clearly apply to areas designated for any 

future new or revised NAAQS. To achieve this, today’s 

final rule restructures two sections of the conformity 

rule, 40 CFR 93.109 and 93.119, and makes changes to 

certain definitions in 40 CFR 93.101. These amendments are 

intended to minimize the need to make administrative 

updates to the conformity rule merely to reference a 

specific new or revised NAAQS. EPA has already undertaken 

two conformity rulemakings primarily for the purpose of 

addressing a new or revised NAAQS. See the March 24, 2010 

Transportation Conformity Rule PM2.5 and PM10 Amendments (“PM 

Amendments”) final rule and the July 1, 2004 final rule (75 

FR 14260, and 69 FR 40004, respectively). Due to other CAA 

requirements, EPA will continue to establish new or revised 

NAAQS in the future. EPA believes that today’s conformity 

rule revisions provide more certainty to implementers 

without compromising air quality benefits from the current 

program. These changes are described in Sections III. and 

V. of today’s final rule.
Page 9 of 58

EPA is also clarifying in today’s final rule the 

additional conformity test option available to current 

ozone “clean data” areas and is extending that option to 

any nonattainment areas for which EPA has developed a clean

data regulation or policy.2 This provision should eliminate 

the need to update the conformity rule in the future in 

order to extend this conformity option to other NAAQS. See 

Section IV. of today’s final rule for further details.

EPA is also finalizing a change to the wording of 

conformity rule section 93.118(b) that does not change its 

requirements. Section 93.118(b) of the conformity rule 

continues to require consistency3 for any years where the 

SIP establishes a budget and for any years that are 

analyzed to meet the requirements in 40 CFR 93.118(d). 

This change simplifies this provision and eliminates 

repetitiveness within the regulation, but does not change 

the requirements for demonstrating consistency. EPA did 

not receive comments on this section, and we are finalizing 

it as proposed.

 

2 Clean data refers to air quality monitoring data determined by EPA to 

indicate attainment of the NAAQS. Note that we are finalizing a minor

change to the definition of clean data found in conformity rule section

93.101; see Section IV. of today’s notice.

3

That is, transportation plan and TIP emissions must be less than or 

equal to the budget(s) in the applicable SIP.
Page 10 of 58

Section VI. covers how today’s final rule affects 

conformity SIPs. A conformity SIP includes a state’s 

specific criteria and procedures for certain aspects of the 

conformity process.4

In the August 13, 2010 Federal Register notice, EPA 

had proposed that a near-term year would have to be 

analyzed when using the budget test when an area’s 

attainment date has passed or has not yet been established 

(75 FR 49435). EPA is not taking final action on this 

proposal at this time. 

Finally, EPA received several comments requesting that 

we issue a rulemaking, rather than guidance, to address 

conformity requirements in areas designated for a distinct 

secondary NAAQS. Transportation conformity applies to any 

NAAQS for transportation-related criteria pollutants, 

including secondary NAAQS.

5 CAA section 176(c) does not 

distinguish between primary and secondary NAAQS. EPA would 

issue future transportation conformity guidance as needed 

to implement new or revised NAAQS, including a distinct 

secondary NAAQS if one is promulgated in the future.

III. Restructure of Section 93.109 -- Tests of Conformity 

 

4 For more information about conformity SIPs, see EPA’s “Guidance for 

Developing Transportation Conformity State Implementation Plans 

(SIPs)”, (EPA-420-B-09-001, January 2009). 

5 See the preamble to the August 13, 2010 proposal for further 

background (75 FR 49441).
Page 11 of 58

for Transportation Plans, TIPs, and Projects -- and 

Changes to Related Sections

A. Overview

Conformity determinations for transportation plans, 

TIPs, and projects not from a conforming transportation 

plan and TIP must include a regional emissions analysis 

that fulfills CAA requirements. The conformity rule 

provides for several different regional conformity tests 

that satisfy statutory requirements in different 

situations. Once a SIP with a budget is submitted for a 

NAAQS and EPA finds the budget adequate for conformity 

purposes or approves the SIP, conformity must be 

demonstrated using the budget test for that pollutant or 

precursor, as described in 40 CFR 93.118. 

EPA has amended the conformity rule on two prior 

occasions to address a new or revised NAAQS. In the July 

1, 2004 final rule (69 FR 40004), EPA amended 40 CFR 93.109 

by adding new paragraphs to describe the regional 

conformity tests for the 1997 ozone areas that do not have 

1-hour ozone budgets, 1997 ozone areas that have 1-hour 

ozone budgets, and 1997 PM2.5 areas. Also, in the March 24, 

2010 PM Amendments rulemaking (75 FR 14260), EPA amended 40 

CFR 93.109 again by adding two new paragraphs to describe 

the regional conformity tests for 2006 PM2.5 areas without 
Page 12 of 58

1997 PM2.5 budgets, and 2006 PM2.5 areas that have 1997 PM2.5

budgets.

Given that CAA section 109(d)(1) requires EPA to 

revisit the NAAQS for criteria pollutants at least every 

five years, and that EPA is in the process of considering 

revisions to other NAAQS per this requirement, EPA 

anticipates other NAAQS revisions will be made in the 

future that will be subject to conformity requirements. 

Today’s action restructures 40 CFR 93.109 to eliminate 

repetition and reduce the need to update the rule each time 

a NAAQS is promulgated. The same hierarchy of conformity 

tests as described below in B. of this section generally 

applies to all areas where conformity is required, and for 

the reasons described below, EPA believes it would apply to 

future nonattainment and maintenance areas for 

transportation-related pollutants or NAAQS. 

B. Description of the Final Rule

In today’s action, EPA is restructuring 40 CFR 93.109 

so that it contains two paragraphs:

 regional conformity tests, which are covered by 

section 93.109(c); and, 

 project-level conformity tests, which are covered by 

section 93.109(d). 
Page 13 of 58

New paragraph (c). Today’s final rule revises 40 CFR 

93.109(c) so that requirements for using the budget test 

and/or interim emissions tests apply for any NAAQS in the 

following way: 

 First, a nonattainment or maintenance area for a 

specific NAAQS must use the budget test, if the area 

has adequate or approved SIP budgets for that specific 

NAAQS (section 93.109(c)(1)). For example, once a 

2006 PM2.5 nonattainment area has adequate or approved 

SIP budgets for the 2006 PM2.5 NAAQS, it must use those 

budgets in the budget test as the regional test of 

conformity for the 2006 PM2.5 NAAQS;

 Second, if an area does not have such budgets but has 

adequate or approved budgets from a SIP that addresses 

a different NAAQS of the same criteria pollutant, 

these budgets must be used in the budget test. Where 

such budgets do not cover the entire area, the interim 

emissions test(s) may also have to be used (section 

93.109(c)(2)). For example, before a 2006 PM2.5 area 

has adequate or approved budgets for the 2006 PM2.5 

NAAQS, it must use the budget test, using budgets from 

an adequate or approved SIP for the 1997 PM2.5 NAAQS, 

if it has them. If these budgets do not cover the 
Page 14 of 58

entire 2006 PM2.5 area, one of the interim emissions 

tests may also have to be used; 

 Third, if an area has no adequate or approved SIP 

budgets for that criteria pollutant at all, it must 

use the interim emissions test(s) (section 

93.109(c)(3)). For example, if a 2006 PM2.5 area has 

no adequate or approved budgets for any PM2.5 NAAQS, it 

must use one of the interim emissions tests, as 

described in 40 CFR 93.119.

These conformity test requirements are unchanged from 

the previous regulation; today’s rulemaking restates them 

in terms that apply to any NAAQS.

In addition, in conformity rule section 93.109(c)(5), 

EPA is expanding the clean data conformity option to all 

clean data areas for which EPA has a clean data regulation 

or policy.6 See Section IV. below for further information.

New paragraph (d). With regard to project-level 

requirements, today’s final rule places the existing rule’s 

requirements for hot-spot analyses of projects in CO, PM10, 

and PM2.5 nonattainment and maintenance areas together in 

one paragraph (section 93.109(d)(1), (2), and (3)). These 

 

6

Clean data refers to air quality monitoring data determined by EPA to 

indicate attainment of the NAAQS. Note that this action finalizes a 

minor change to the definition of clean data which is found in section 

93.101 of the conformity rule; see Section IV. of today’s rulemaking.
Page 15 of 58

requirements are unchanged from the previous regulation; 

today’s rulemaking simply groups them together under one 

paragraph.7 

Related amendments. Today’s final rule removes the 

definitions for “1-hour ozone NAAQS”, “8-hour ozone NAAQS”, 

“24-hour PM10 NAAQS”, “1997 PM2.5 NAAQS”, “2006 PM2.5 NAAQS”, 

and “Annual PM10 NAAQS” from 40 CFR 93.101. These 

definitions are no longer necessary because the updated 

regulatory text for sections 93.109 and 93.1198 applies to 

any and all NAAQS of those pollutants for which conformity 

applies. In addition, today’s final rule updates 

references to 40 CFR 93.109 found elsewhere in the 

regulation. Finally, today’s final rule corrects a 

reference to the consultation requirements found in 

93.109(g)(2)(iii) which applies to isolated rural areas.

C. Rationale and Response to Comments

EPA is restructuring 40 CFR 93.109 because a recent 

court decision has already established the legal parameters 

for regional conformity tests. In Environmental Defense v. 

EPA, 467 F.3d 1329 (DC Cir. 2006), the Court of Appeals for 

 

7 Project-level conformity determinations are typically developed during 

the National Environmental Policy Act (NEPA) process, although 

conformity requirements are separate from NEPA-related requirements. 

Today’s action to restructure 40 CFR 93.109 does not affect how NEPArelated requirements are implemented in the field.

8 See Section V. of today’s rulemaking for revisions to 40 CFR 93.119.
Page 16 of 58

the District of Columbia Circuit held that where a motor 

vehicle emissions budget developed for the revoked 1-hour 

ozone NAAQS existed in an approved SIP, that budget must be 

used to demonstrate conformity to the 8-hour ozone NAAQS 

until the SIP is revised to include budgets for the new (or 

revised) NAAQS. EPA incorporated the court’s decision for 

ozone conformity tests in its January 24, 2008 final rule 

(73 FR 4434). While the Environmental Defense case 

concerned ozone, EPA believes the court’s holding is 

relevant for other pollutants for which conformity must be 

demonstrated. Consequently, EPA believes the hierarchy of 

regional conformity tests described above, which is already 

found in the existing rule for 1997 ozone and 2006 PM2.5

areas, would apply for any NAAQS of a pollutant for which 

the conformity rule applies.

EPA’s restructuring of 40 CFR 93.109 and elimination 

of certain definitions in 40 CFR 93.101, along with the 

standardization of the baseline year in 40 CFR 93.119 (see 

Section V. of today’s final rule for details), should make 

the rule sufficiently flexible to address any future NAAQS 

changes, including the promulgation of a new or revised 

NAAQS or revocation of a NAAQS, without additional 

rulemakings.

The restructured section 93.109 does not change the 
Page 17 of 58

criteria and procedures for determining conformity of 

transportation plans, TIPs, and projects and is consistent 

with the regional conformity test requirements described in 

the PM Amendments final rule (75 FR 14266-14274). The 

rationale for the required regional tests has been 

described in previous rulemakings.9 The rationale for the 

requirements for project-level conformity tests in CO, 

PM2.5, and PM10 areas has also been described in previous 

rulemakings.10

Today’s restructuring of 40 CFR 93.109 reduces the

likelihood that EPA would have to amend the conformity rule 

when new or revised NAAQS are promulgated, which has 

several benefits. First, implementers will know the 

requirements for regional conformity tests for any 

potential area designated nonattainment for a new or 

revised NAAQS, even before such area’s official 

designation, and will not need to wait for any additional 

conformity rulemaking from EPA to know what type of 

regional conformity test will apply. Second, reducing the 

need to amend the conformity regulation each time a NAAQS 

 

9 See EPA’s March 24, 2010 final rule (75 FR 14266-14273). See also 

EPA’s July 1, 2004 final rule (69 FR 40019-40031).

10 For further details on project-level conformity test requirements, 

please refer to the March 10, 2006 final rule (71 FR 12469-12506). See 

also EPA’s January 24, 2008 final rule (73 FR 4432-4434), EPA’s July 1, 

2004 final rule (69 FR 40036-40038; 40056-40058), the August 15, 1997 

final rule (62 FR 43798), and the November 24, 1993 final rule (58 FR 

62199-62201; 62207-62208; 62212-62213).
Page 18 of 58

change is made will save government resources and taxpayer 

dollars, and will reduce stakeholder efforts needed to keep 

track of regulatory changes. 

All commenters who addressed this proposal supported 

EPA’s approach for restructuring 40 CFR 93.109. Several 

commenters agreed with EPA that these changes will help 

streamline the conformity regulation and reduce the need to 

revise the conformity rule when new or revised NAAQS are 

promulgated. One commenter opined that the restructuring 

of 40 CFR 93.109 provides a clear and concise organization 

of the conformity requirements and agreed with EPA’s 

rationale that it will be beneficial for implementing 

organizations to know the conformity requirements in 

advance of any new or revised NAAQS.

A few commenters requested that EPA clarify whether 

areas that have an adequate or approved NOx SIP budget for 

a specific NAAQS (e.g., the 1997 ozone NAAQS) would have to 

use that NOx budget to demonstrate conformity for another 

pollutant, such as PM2.5. 

A NOx budget in an ozone SIP would apply for 

conformity for an ozone NAAQS only, and could not be used 

as a budget for any other pollutant. CAA section 

176(c)(1)(A) establishes that nonattainment and maintenance 

areas must demonstrate conformity to a SIP’s “purpose of 
Page 19 of 58

eliminating or reducing the severity and number of 

violations of the national ambient air quality standards 

and achieving expeditious attainment of such standards.” 

The purpose of a SIP is tied to the pollutant it addresses. 

The 2006 court case cited above in this section supports 

this point. In that ruling, the court held that where a 

budget developed for the revoked 1-hour ozone NAAQS existed 

in an approved SIP, that budget must be used to demonstrate 

conformity to the 8-hour ozone NAAQS until a SIP is revised 

to include budgets for the new or revised NAAQS. The court 

did not refer to adequate or approved NOx or VOC budgets 

from a SIP that addressed a pollutant other than ozone, and 

did not indicate that such budgets would need to be used. 

In accordance with this court decision, if, for example, a 

1997 ozone area has an approved 1997 ozone attainment 

demonstration with a NOx budget, this NOx budget must be 

used to demonstrate conformity for the 1997 ozone NAAQS and 

could also be used to demonstrate conformity for any future 

ozone NAAQS before the area has a SIP for that ozone NAAQS. 

However, the NOx budget could not be used to demonstrate 

conformity for a PM or NO2 NAAQS because doing so would not 

be consistent with CAA section 176(c) requirements that 

conformity be demonstrated to the relevant SIP. 
Page 20 of 58

Finally, while pollutants may have precursors in 

common, control strategies may differ by pollutant and the 

seasons for which the budget is established may differ by 

pollutant as well. For example, precursor SIP budgets for 

the ozone NAAQS address a typical summer day, because ozone 

is a summertime air quality problem. However, PM2.5

violations in the same geographic area may have occurred 

during winter months. An ozone precursor SIP budget 

established for a typical summer day has no relevance in 

addressing a wintertime PM2.5 problem. 

EPA believes that section 93.109(c)(2) in today’s 

final rule provides sufficient clarity for these situations 

because it specifies that where an area does not have an 

adequate or approved SIP budget for a NAAQS, it would use 

an approved or adequate SIP budget(s) for another NAAQS of 

the same pollutant as the test of conformity. No 

additional changes are necessary.

IV. Additional Option for Areas That Qualify for EPA’s 

Clean Data Regulations or Policies

A. Overview

Prior to today’s final rule, the conformity rule 

provided an additional regional conformity test option for 

certain moderate and above ozone nonattainment areas that 

meet the criteria of EPA’s existing clean data regulation 
Page 21 of 58

and policy. Today’s rule clarifies this option and extends 

it to any nonattainment areas that are covered by EPA’s 

clean data regulations or clean data policies. See Section 

IV. of the August 13, 2010 proposal for further background 

on EPA’s clean data regulations and policies (75 FR 49439).

B. Description of the Final Rule

Today, EPA is clarifying that any nonattainment area 

that EPA determines has air quality monitoring data that 

meet the requirements of 40 CFR parts 50 and 58 and that 

show attainment of a NAAQS - a “clean data” area11 - can 

choose to satisfy the regional conformity test requirements 

by using on-road emissions from the most recent year of 

clean data as the budget(s) for that NAAQS rather than 

using the interim emissions test(s) per 40 CFR 93.119. The 

area may do this if the following are true:

 The state or local air quality agency requests that 

budgets be established by the EPA determination of 

attainment (Clean Data) rulemaking for that NAAQS, 

and EPA approves the request; and,

 The area has not submitted a maintenance plan for 

that NAAQS and EPA has determined (through the Clean 

Data rulemaking) that the area is not subject to the 

CAA reasonable further progress and attainment 

 

11 See conformity rule section 93.101 for a definition of “clean data.”
Page 22 of 58

demonstration requirements for the relevant NAAQS. 

Otherwise, clean data areas for a NAAQS must satisfy 

the regional conformity test requirements using either the 

budget test if they have adequate or approved SIP budgets 

(per 40 CFR 93.109 and 93.118), or the interim emissions 

test(s) per 40 CFR 93.119 if they do not have adequate or 

approved SIP budgets. 

In today’s rule, EPA is not making changes to its 

existing clean data regulations or policies or to the 

conformity option for clean data areas. EPA is merely 

clarifying this conformity option and extending it to any 

nonattainment areas that are covered by EPA’s clean data 

regulations or clean data policies.

The regulatory text for this flexibility is found in 

section 93.109(c)(5) of the conformity rule. This text 

clarifies that before this flexibility may be used: 1) the 

state or local air quality agency must make the request 

that the emissions in the most recent year for which EPA 

determines the area is attaining (i.e., the most recent 

year that the area has clean data) be used as budgets, and 

2) EPA would have to approve that request through noticeand-comment rulemaking.

Today’s rule also updates the definition of "clean 

data" in 40 CFR 93.101 to describe this term more 
Page 23 of 58

accurately. The updated definition references the 

appropriate requirements at 40 CFR part 50, as well as part 

58.

C. Rationale and Response to Comments

EPA believes that it is reasonable to extend the same 

conformity option available to clean data ozone areas to 

all clean data areas for which EPA has a clean data 

regulation or policy. Furthermore, this provision should 

work with any clean data policy or regulation that EPA 

develops; thus, it would eliminate the need to update the 

conformity rule in the future in order to extend this 

conformity option to any NAAQS for which EPA develops a 

clean data policy or regulation. See EPA’s previous 

discussion and rationale for the clean data conformity 

option in July 1, 2004 final rule (69 FR 40019-40021). See 

also the preamble to the 1996 conformity proposal and 1997 

final rule (July 9, 1996, 61 FR 36116, and August 15, 1997, 

62 FR 43784-43785, respectively). 

Several commenters requested that EPA clarify whether 

the use of the most recent year of clean data as the budget 

becomes binding once EPA approves it for use in completing 

regional conformity analyses. These commenters also wanted 

assurance that the state or local air quality agency would 

need to use the interagency and public consultation process 
Page 24 of 58

before such budgets are submitted to EPA for approval. As 

EPA explained in its proposed rule (August 13, 2010, 75 FR 

49439), once the state or local air quality agency makes 

the request that the emissions in the most recent year for 

which the area is attaining be used as the budget, and EPA 

approves that request through a rulemaking, this level of 

emissions becomes the approved budget for conformity 

purposes in the clean data area for the relevant NAAQS.12 

The area may not revert back to using the interim emissions 

test(s) to demonstrate conformity once a budget has been 

established through a rulemaking, regardless of whether 

such budget is approved in a Clean Data rulemaking for a 

NAAQS or is approved as part of a control strategy SIP. 

Note that should EPA subsequently determine that the area 

has violated the relevant NAAQS and withdraw the 

determination of attainment through appropriate 

rulemaking,13 EPA will also withdraw its approval for the 

clean data budget. 

Once a clean data area submits a maintenance plan, and 

its budget(s) are found adequate or approved, the 

 

12 If EPA subsequently finds a different SIP budget adequate or approves 

a SIP containing a budget, then that budget would be used for 

conformity purposes, as applicable, under 40 CFR 93.118.

13 See the November 29, 2005 Phase 2 Ozone Implementation rulemaking for 

the 1997 ozone NAAQS (70 FR 71644-71646), 40 CFR 51.918, and the April 

25, 2007 Clean Air Fine Particle Implementation Rule for the 1997 PM2.5

NAAQS (72 FR 20603-20605), 40 CFR 1004(c).
Page 25 of 58

maintenance plan budget(s) must be used for conformity 

based on the regulation at 40 CFR 93.118(b).

The conformity rule at 93.105(a)(1) requires 

interagency consultation in SIP development. The final 

rule is consistent with prior conformity rulemakings that 

require any clean data budgets to be subject to the 

existing interagency consultation process and public 

comment. EPA established in its August 15, 1997 final rule 

(62 FR 43784-43785) that, regardless of whether a budget is 

created through the SIP process or through a Clean Data 

rulemaking, the interagency consultation process must be 

used and the public must be provided an opportunity to 

comment. See the August 15, 1997 final rule for further 

details. 

For details on EPA’s clean data regulations and 

policies, see the November 29, 2005 Phase 2 Ozone 

Implementation rulemaking for the 1997 ozone NAAQS (70 FR 

71644-71646), 40 CFR 51.918, and the April 25, 2007 Clean 

Air Fine Particle Implementation Rule for the 1997 PM2.5

NAAQS (72 FR 20603-20605, 40 CFR 1004(c)). See also 

various determinations of attainment for PM10 nonattainment 

areas using EPA’s Clean Data policy (October 30, 2006 final 

rule (71 FR 63642), February 8, 2006 final rule (71 FR 

6352), March 14, 2006 final rule (71 FR 13021), March 23, 
Page 26 of 58

2010 proposed rule (75 FR 13710)). 

V. Restructure of the Baseline Year Test for Existing 

NAAQS and Baseline Year Test for Future NAAQS

A. Overview

As stated above, conformity is demonstrated with one 

or both of the interim emissions tests if an adequate or 

approved SIP budget is not available. The interim 

emissions tests include different forms of the “build/nobuild” test and “baseline year” test. In general, the 

baseline year test compares emissions from the planned 

transportation system to emissions that occurred in the 

relevant baseline year. The build/no-build test compares 

emissions from the planned (or “build”) transportation 

system with the existing (or “no-build”) transportation 

system in the analysis year. 

B. Description of Final Rule 

Today’s action revises 40 CFR 93.119 to apply more 

generally to any NAAQS for a given pollutant. First, the 

section has been reorganized to place the baseline years 

for existing NAAQS in one paragraph (revised paragraph 

(e)). Today’s action also revises 40 CFR 93.119 to define 

the baseline year for any NAAQS promulgated after 1997 by 

reference to another requirement. Rather than naming a 

specific year, the conformity rule defines the baseline 
Page 27 of 58

year for conformity purposes as the most recent year for 

which EPA’s Air Emissions Reporting Requirements (AERR) (40 

CFR Part 51.30(b)) requires submission of on-road mobile 

source emissions inventories, as of the effective date of 

EPA’s nonattainment designations for any NAAQS promulgated

after 1997. AERR requires on-road mobile source emission 

inventories to be submitted for every third year, for 

example, 2002, 2005, 2008, 2011, 2014, etc.14

Today’s rule is consistent with the baseline year 

definition finalized for the 2006 PM2.5 NAAQS in the PM 

Amendments final rule. In the PM Amendments final rule, 

this definition applied to only areas designated for any 

PM2.5 NAAQS other than the 1997 PM2.5 NAAQS. Today’s action 

amends the conformity rule to establish the same baseline 

year definition for new or revised NAAQS of any pollutant 

promulgated after 1997, not just the PM2.5 NAAQS. See the 

March 24, 2010 PM Amendments final rule (75 FR 14265-14266) 

for further details. 

This definition will automatically establish a 

relevant baseline year for conformity purposes for any 

areas designated nonattainment for all future NAAQS. For 

all future NAAQS, EPA will identify the baseline year that 

 

14 These are known as Three-Year Cycle Inventories. See 40 CFR Part 

51.30(b) and the EPA’s December 17, 2008 final rule (73 FR 76539) for 

more details. 
Page 28 of 58

results from today’s rule in guidance and will maintain a 

list of baseline years on EPA’s web site.15 Once the 

baseline year is established according to this provision, 

it will not change (i.e., the baseline year would not be a 

rolling baseline year for a given NAAQS). Today’s final 

rule does not change any baseline years already established 

for conformity purposes prior to today’s action. 

The existing interagency consultation process (40 CFR 

93.105(c)(1)(i)) must be used to determine the latest 

assumptions and models for generating baseline year motor 

vehicle emissions to complete any baseline year test. The 

baseline year emissions level that is used in conformity 

must be based on the latest planning assumptions available, 

the latest emissions model, and appropriate methods for 

estimating travel and speeds as required by 40 CFR 93.110, 

93.111, 93.122 of the current conformity rule.

As described in earlier rulemakings, the baseline year 

interim emissions test can be completed with a submitted or 

draft baseline year motor vehicle emissions SIP inventory, 

if the SIP reflects the latest information and models.16 An 

MPO or state DOT, in consultation with state and local air 

agencies, could also develop baseline year emissions as 

 

15 See www.epa.gov/otaq/stateresources/transconf/baseline.htm

16 See the March 24, 2010 final rule (75 FR 14265) and the July 1, 2004 

final rule (69 FR 40015). 
Page 29 of 58

part of the conformity analysis. EPA believes that a 

submitted or draft SIP baseline inventory may be the most 

appropriate source for completing the baseline year tests 

for an area’s first conformity determination under a new or 

revised NAAQS. This is due to the fact that SIP 

inventories are likely to be under development at the same 

time as these conformity determinations, and such 

inventories must be based on the latest available data at 

the time they are developed (CAA section 172(c)(3)). 

C. Rationale and Response to Comments

EPA believes that today’s final rule results in an 

environmentally protective and legal baseline year for 

conformity for any NAAQS promulgated after 1997 and best 

accomplishes several important goals.

First, as described in the August 13, 2010 proposed 

rule (75 FR 49440), EPA believes it is important to 

coordinate the conformity baseline year with the year used 

for SIP planning and an emissions inventory year. This was 

EPA’s rationale for using 2002 as the baseline year for 

interim emissions tests in nonattainment areas for the 1997 

ozone and PM2.5 NAAQS (69 FR 40014-40015). It was also 

EPA’s rationale for finalizing the same baseline year 

definition in today’s final rule for 2006 PM2.5

nonattainment areas in the March 24, 2010 final rule: this 
Page 30 of 58

definition resulted in a conformity baseline year of 2008 

for the 2006 PM2.5 NAAQS (75 FR 14265-14266). Therefore, 

today’s conformity baseline year is consistent with how EPA 

has implemented the conformity baseline year for new or 

revised NAAQS in the past. 

Second, today’s baseline year definition also ensures 

that the baseline year for any future NAAQS is always 

fairly recent, which is appropriate for meeting CAA 

conformity requirements and is environmentally protective. 

Because the AERR requires submission of inventories every 

three years, the baseline year for any NAAQS promulgated 

after 1997 will always be either the same year as the year 

in which designations are effective, or one or two years 

prior to the effective date of the designations. For 

example, in the case of the 2006 PM2.5 NAAQS, nonattainment 

designations became effective on December 14, 2009, and the 

baseline year for conformity purposes is 2008 for areas 

designated nonattainment for the 2006 PM2.5 NAAQS, the year 

before the effective date of the designations (See the PM 

Amendments final rule for details (75 FR 14265-14266)). 

EPA also believes that coordinating the baseline year 

for interim emissions tests with other data collection and 

inventory requirements would allow state and local 

governments to use their resources more efficiently. Given 
Page 31 of 58

that the CAA requires EPA to review the NAAQS for possible 

revision once every five years, today’s baseline year 

provision standardizes the process for selecting an 

appropriate baseline year for any NAAQS promulgated in the 

future. 

Finally, today’s rule for the baseline year definition 

provides implementers with knowledge of the baseline year 

for any future new or revised NAAQS upon the effective date 

of nonattainment designations for that NAAQS, without 

having to wait for EPA to amend the conformity rule. As a 

result, MPOs and other implementers should understand 

conformity requirements for future NAAQS revisions more 

quickly, which should enable them to fully utilize the 12-

month conformity grace period to complete conformity 

determinations for new nonattainment areas. 

Several commenters voiced support for coordinating the 

conformity baseline year with an emissions inventory year, 

in part because EPA could avoid additional rulemakings to 

implement future baseline year changes. Several commenters 

also agreed that this change would be beneficial since 

implementing organizations would know the conformity 

requirements in advance of any new or revised NAAQS. 

Some commenters expressed concern that emissions 

inventories are not always submitted on time and 
Page 32 of 58

recommended that the conformity rule require that the 

baseline year for the baseline year interim emissions test 

be the most recent emissions inventory year that has been 

completed and submitted to EPA. One commenter recommended 

that the baseline year be at least three years older than 

the date the first conformity determination is required and 

that if the most recent completed emissions inventory is 

less than three years old, the previous emissions inventory 

should be used. However, these suggestions could lead to 

different baseline years in areas designated for the same 

NAAQS, which may not meet statutory requirements, and would 

be confusing to track as well as inequitable. EPA’s final 

rule establishes the same baseline year for every area 

designated for a particular NAAQS regardless of whether an 

individual area submitted its inventory on time. If an 

area has not submitted a final AERR inventory for the 

relevant conformity baseline year, there are other options 

for generating on-road mobile source emissions in the 

baseline year, discussed above under B. of this section. 

Another commenter opined that if a later year than 

currently required is used as a baseline year for the 

baseline year interim emissions test, and emissions are on 

a downward trend, the proposed change would make the 

baseline year interim emissions test more stringent than 
Page 33 of 58

what was proposed. The commenter suggested that this 

concern may be mitigated by keeping the baseline year for 

all future NAAQS at or near the year 2002 that was 

established for the 1997 ozone and PM2.5 NAAQS. 

Today’s final rule is intended to ensure the same 

level of stringency for all NAAQS regardless of when the 

NAAQS was promulgated. The conformity baseline year of 

2002 that EPA established for the 1997 ozone and PM2.5 NAAQS 

is several years prior to the effective date of the 1997 

ozone and PM2.5 ozone nonattainment designations. Area 

designations for the 1997 ozone NAAQS became effective on 

June 15, 2004 and area designations for the 1997 PM2.5 NAAQS 

became effective on April 5, 2005 (See the April 30, 2004 

(69 FR 23858) and the January 5, 2005 (70 FR 944) final 

rules, respectively). Further, if there is a downward 

trend in on-road mobile source emissions, it makes sense to 

reflect that downward trend in the interim emissions test. 

Today’s final rule accomplishes that by ensuring that the 

baseline year is always fairly recent.

Finally, EPA would like to clarify a couple of points 

related to this comment. First, the commenter referred to 

the baseline year of 2002 in the “current conformity rule.” 

That baseline year of 2002 was established in 2004 for the 

1997 ozone and PM2.5 NAAQS and it remains the baseline year 
Page 34 of 58

only for these NAAQS. Second, the baseline year definition 

in today’s rule is the same definition EPA established as 

the baseline year for areas designated nonattainment for 

the 2006 PM2.5 NAAQS in the March 24, 2010 PM Amendments 

rule. Thus, today’s definition had already been part of 

the current conformity rule prior to today’s action. 

VI. How Do These Amendments Affect Conformity SIPs?

Today’s action does not affect existing conformity 

SIPs that were prepared in accordance with current CAA 

requirements since the final rule does not affect the 

provisions that are required to be in a conformity SIP. 

CAA section 176(c)(4)(E) requires a conformity SIP to 

include the state’s criteria and procedures for interagency 

consultation (40 CFR 93.105) and two additional provisions 

related to written commitments for certain control and 

mitigation measures (40 CFR 93.122(a)(4)(ii) and 

93.125(c)). 

However, the conformity rule also requires states to 

submit a new or revised conformity SIP to EPA within 12 

months of the Federal Register publication date of any 

final conformity amendments if a state’s conformity SIP 

includes the provisions of such final amendments (40 CFR 

51.390(c)). Therefore, such a conformity SIP revision is 

required to be submitted by [INSERT DATE ONE YEAR AFTER 
Page 35 of 58

PUBLICATION IN THE FEDERAL REGISTER] in states with 

approved conformity SIP’s containing provisions addressed 

by today’s action. EPA encourages these states to revise 

their conformity SIP to include only the three required 

sections so that future changes to the conformity rule do 

not require further revisions to conformity SIPs. EPA will 

continue to work with states to approve such revisions as 

expeditiously as possible through flexible administrative 

techniques, such as parallel processing and direct final 

rulemaking.

Finally, any state that has not previously been 

required to submit a conformity SIP to EPA must submit a 

conformity SIP within 12 months of an area’s nonattainment 

designation (40 CFR 51.390(c)). 

For additional information on conformity SIPs, please 

refer to the January 2009 guidance entitled, “Guidance for 

Developing Transportation Conformity State Implementation 

Plans” available on EPA’s website at 

www.epa.gov/otaq/stateresources/transconf/policy/420b09001.

pdf. 

VII.Statutory and Executive Order Reviews 

A. Executive Order 12866: Regulatory Planning and Review

Under Executive Order 12866, (58 FR 51735; October 4, 

1993), this action is a "significant regulatory action” 
Page 36 of 58

because it raises novel legal and policy issues. 

Accordingly, EPA submitted this action to the Office of 

Management and Budget (OMB) for review under Executive 

Orders 12866 and 13563 (76 FR 3821, January 21, 2011) and 

any changes made in response to OMB recommendations have 

been documented in the docket for this action.

B. Paperwork Reduction Act

This action does not impose any new information 

collection burden. The information collection requirements 

of EPA’s existing transportation conformity regulations and 

the proposed revisions in today’s action are already 

covered by EPA information collection request (ICR)

entitled, “Transportation Conformity Determinations for 

Federally Funded and Approved Transportation Plans, 

Programs and Projects.” The Office of Management and 

Budget (OMB) has previously approved the information 

collection requirements contained in the existing 

conformity regulations under the provisions of the 

Paperwork Reduction Act, 44 U.S.C. 3501 et seq. and has 

assigned OMB control number 2060-0561. The OMB control 

numbers for EPA's regulations in 40 CFR are listed in 40 

CFR Part 9.

C. Regulatory Flexibility Act
Page 37 of 58

The Regulatory Flexibility Act (RFA) generally 

requires an Agency to prepare a regulatory flexibility 

analysis of rules subject to notice and comment rulemaking 

requirements under the Administrative Procedure Act or any 

other statute unless the Agency certifies that the rule 

will not have a significant economic impact on a 

substantial number of small entities. Small entities 

include small businesses, small not-for-profit 

organizations and small government jurisdictions. 

For purposes of assessing the impacts of today’s final 

rule on small entities, small entity is defined as: (1) a 

small business as defined by the Small Business 

Administration’s (SBA) regulations at 13 CFR 121.201; (2) a 

small governmental jurisdiction that is a government of a 

city, county, town, school district or special district 

with a population of less than 50,000; and (3) a small 

organization that is any not-for-profit enterprise that is 

independently owned and operated and is not dominant in its 

field.

After considering the economic impacts of today’s 

final rule on small entities, I certify that this action 

will not have a significant economic impact on a 

substantial number of small entities. This regulation 

directly affects federal agencies and metropolitan planning 
Page 38 of 58

organizations that, by definition, are designated under 

federal transportation laws only for metropolitan areas 

with a population of at least 50,000. These organizations 

do not constitute small entities within the meaning of the 

Regulatory Flexibility Act. Therefore, this final rule 

will not impose any requirements on small entities.

D. Unfunded Mandates Reform Act

This action does not contain a Federal mandate that 

may result in expenditures of $100 million or more for 

state, local, and tribal governments, in the aggregate, or 

the private sector in any one year. This final rule 

implements already established law that imposes conformity 

requirements and does not itself impose requirements that 

may result in expenditures of $100 million or more in any 

year. Thus, this rule is not subject to the requirements 

of Sections 202 and 205 of the UMRA.

This final rule is also not subject to the 

requirements of Section 203 of UMRA because it contains no 

regulatory requirements that might significantly or 

uniquely affect small governments. This rule will not 

significantly or uniquely impact small governments because 

it directly affects federal agencies and metropolitan

planning organizations that, by definition, are designated 
Page 39 of 58

under federal transportation laws only for metropolitan 

areas with a population of at least 50,000. 

E. Executive Order 13132: Federalism

This action does not have federalism implications. It 

will not have substantial direct effects on the states, on 

the relationship between the national government and the 

states, or on the distribution of power and 

responsibilities among the various levels of government, as 

specified in Executive Order 13132. The CAA requires 

conformity to apply in certain nonattainment and 

maintenance areas as a matter of law, and this action 

merely establishes and revises procedures for 

transportation planning entities in subject areas to follow 

in meeting their existing statutory obligations. Thus, 

Executive Order 13132 does not apply to this action.

F. Executive Order 13175: Consultation and Coordination 

with Indian Tribal Governments

This action does not have tribal implications, as 

specified in Executive Order 13175 (65 FR 67249, November 

9, 2000). The CAA requires conformity to apply in any area 

that is designated nonattainment or maintenance by EPA. 

Because today’s amendments to the conformity rule do not 

significantly or uniquely affect the communities of Indian 
Page 40 of 58

tribal governments, Executive Order 13175 does not apply to 

this action. 

G. Executive Order 13045: Protection of Children from 

Environmental Health and Safety Risks

This action is not subject to Executive Order 13045 

(62 FR 19885, April 23, 1997) because it is not 

economically significant as defined in EO 12866, and 

because the Agency does not have reason to believe the 

environmental health or safety risks addressed by this 

action present a disproportionate risk to children. 

H. Executive Order 13211: Actions Concerning Regulations 

That Significantly Affect Energy Supply, Distribution, 

or Use

This action is not a “significant energy action” as 

defined in Executive Order 13211 (66 FR 18355 (May 22, 

2001)), because it is not likely to have a significant 

adverse effect on the supply, distribution, or use of 

energy. It does not create a serious inconsistency or 

otherwise interfere with an action taken or planned by 

another agency regarding energy. 

I. National Technology Transfer and Advancement Act

Section 12(d) of the National Technology Transfer and 

Advancement Act of 1995 (“NTTAA”), Public Law No. 104-113, 

Section 12(d) (15 U.S.C. 272 note) directs EPA to use 
Page 41 of 58

voluntary consensus standards in its regulatory activities 

unless to do so would be inconsistent with applicable law 

or otherwise impractical. Voluntary consensus standards 

are technical standards (e.g., materials specifications, 

test methods, sampling procedures, and business practices) 

that are developed or adopted by voluntary consensus 

standards bodies. NTTAA directs EPA to provide Congress, 

through OMB, explanations when the Agency decides not to 

use available and applicable voluntary consensus standards.

This action does not involve technical standards. 

Therefore, EPA did not consider the use of any voluntary 

consensus standards.

J. Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and LowIncome Populations.

Executive Order (EO) 12898 (59 FR 7629 (Feb. 16, 

1994)) establishes federal executive policy on 

environmental justice. Its main provision directs federal 

agencies, to the greatest extent practicable and permitted 

by law, to make environmental justice part of their mission 

by identifying and addressing, as appropriate, 

disproportionately high and adverse human health or 

environmental effects of their programs, policies, and 
Page 42 of 58

activities on minority populations and low-income 

populations in the United States. 

EPA has determined that this final rule will not have

disproportionately high and adverse human health or 

environmental effects on minority or low-income populations 

because it maintains or increases the level of 

environmental protection for all affected populations 

without having any disproportionately high and adverse 

human health or environmental effects on any population, 

including any minority or low-income population. 

K. Congressional Review Act

The Congressional Review Act, 5 U.S.C. 801 et seq., as 

added by the Small Business Regulatory Enforcement Fairness 

Act of 1996, generally provides that before a rule may take 

effect, the agency promulgating the rule must submit a rule 

report, which includes a copy of the rule, to each House of 

the Congress and to the Comptroller General of the United 

States. EPA will submit a report containing this rule and 

other required information to the U.S. Senate, the U.S. 

House of Representatives, and the Comptroller General of 

the United States prior to publication of the rule in the 

Federal Register. A Major rule cannot take effect until 60 

days after it is published in the Federal Register. This 

action is not a major rule as defined by 5 U.S.C. 804(2). 
Page 43 of 58

This rule will be effective [INSERT DATE 30 DAYS AFTER 

PUBLICATION IN THE FEDERAL REGISTER].
Page 44 of 58

Transportation Conformity Rule Restructuring Amendments –

Page 44 of 58

List of Subjects in 40 CFR Part 93

Administrative practice and procedure, Air pollution 

control, Carbon monoxide, Clean Air Act, Environmental 

protection, Highways and roads, Intergovernmental 

relations, Mass transportation, Nitrogen Dioxide, 

Ozone, Particulate matter, Transportation, Volatile 

organic compounds. 

Dated: _________________________________

_____________________________________________

Lisa P. Jackson, 

Administrator
Page 45 of 58

For the reasons discussed in the preamble, 40 CFR Part 

93 is amended as follows: 

PART 93 – [AMENDED]

1. The authority citation for Part 93 continues to read as 

follows:

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

2. Section 93.101 is amended by removing paragraphs (1) 

through (6) of the definition for “National ambient air 

quality standards (NAAQS)” and by revising the 

definition for “Clean data” to read as follows:

§93.101 Definitions.

* * * * *

Clean data means air quality monitoring data 

determined by EPA to meet the applicable requirements 

of 40 CFR Parts 50 and 58 and to indicate attainment 

of a NAAQS.

* * * * *

§93.105 [Amended]

3. Section 93.105(c)(1)(vi) is amended by removing the 

citation “§93.109(n)(2)(iii)” and adding in its place the 

citation “§93.109(g)(2)(iii)”. 

4. Section 93.109 is amended as follows:
Page 46 of 58

a. By revising paragraphs (b) introductory text, (c), 

and (d);

b. By removing paragraphs (e) through (k), and 

redesignating paragraphs (l), (m), and (n) as 

paragraphs (e), (f), and (g);

c. In newly redesignated paragraph (g)(2),

i. In paragraph (g)(2) introductory text, by 

removing the citation “paragraphs (c) through (m)” 

and adding in its place “paragraph (c)”;

ii. In paragraph (g)(2)(iii), by removing the 

citation “paragraph (n)(2)(ii)” and adding in its 

place “paragraph (g)(2)(ii)”;

iii. In paragraph (g)(2)(iii), by removing the 

citation “paragraph (n)(2)(ii)(C)” and adding in 

its place “paragraph (g)(2)(ii)(C)”;

d. In paragraph (g)(2)(iii), by removing the citation 

“§93.105(c)(1)(vii)” and adding in its place 

“§93.105(c)(1)(vi)”.

§93.109 Criteria and procedures for determining conformity 

of transportation plans, programs, and projects: General.

* * * * *

(b) Table 1 in this paragraph indicates the criteria 

and procedures in §§93.110 through 93.119 which apply for 

transportation plans, TIPs, and FHWA/FTA projects. 
Page 47 of 58

Paragraph (c) of this section explains when the budget and 

interim emissions tests are required for each pollutant and 

NAAQS. Paragraph (d) of this section explains when a hotspot test is required. Paragraph (e) of this section 

addresses conformity requirements for areas with approved 

or adequate limited maintenance plans. Paragraph (f) of 

this section addresses nonattainment and maintenance areas 

which EPA has determined have insignificant motor vehicle 

emissions. Paragraph (g) of this section addresses 

isolated rural nonattainment and maintenance areas. Table 

1 follows:

* * * * *

(c) Regional conformity test requirements for all 

nonattainment and maintenance areas. This provision 

applies one year after the effective date of EPA’s 

nonattainment designation for a NAAQS in accordance with 

§93.102(d) and until the effective date of revocation of 

such NAAQS for an area. In addition to the criteria listed 

in Table 1 in paragraph (b) of this section that are 

required to be satisfied at all times, in such 

nonattainment and maintenance areas conformity 

determinations must include a demonstration that the budget 

and/or interim emissions tests are satisfied as described 

in the following:
Page 48 of 58

(1) In all nonattainment and maintenance areas for a 

NAAQS, the budget test must be satisfied as required by 

§93.118 for conformity determinations for such NAAQS made 

on or after:

(i) The effective date of EPA's finding that a motor 

vehicle emissions budget in a submitted control strategy 

implementation plan revision or maintenance plan for such 

NAAQS is adequate for transportation conformity purposes;

(ii) The publication date of EPA's approval of such a 

budget in the Federal Register; or

(iii) The effective date of EPA's approval of such a 

budget in the Federal Register, if such approval is 

completed through direct final rulemaking.

(2) Prior to paragraph (c)(1) of this section applying 

for a NAAQS, in a nonattainment area that has approved or 

adequate motor vehicle emissions budgets in an applicable 

implementation plan or implementation plan submission for 

another NAAQS of the same pollutant, the following tests 

must be satisfied: 

(i) If the nonattainment area covers the same 

geographic area as another NAAQS of the same pollutant, the 

budget test as required by §93.118 using the approved or 

adequate motor vehicle emissions budgets for that other 

NAAQS;
Page 49 of 58

(ii) If the nonattainment area covers a smaller 

geographic area within an area for another NAAQS of the 

same pollutant, the budget test as required by §93.118 for 

either:

(A) The nonattainment area, using corresponding 

portion(s) of the approved or adequate motor vehicle 

emissions budgets for that other NAAQS, where such 

portion(s) can reasonably be identified through the 

interagency consultation process required by §93.105; or

(B) The area designated nonattainment for that other 

NAAQS, using the approved or adequate motor vehicle 

emissions budgets for that other NAAQS. If additional 

emissions reductions are necessary to meet the budget test 

for the nonattainment area for a NAAQS in such cases, these 

emissions reductions must come from within such 

nonattainment area;

(iii) If the nonattainment area covers a larger 

geographic area and encompasses an entire area for another 

NAAQS of the same pollutant, then either (A) or (B) must be 

met:

(A)(1) The budget test as required by §93.118 for the 

portion of the nonattainment area covered by the approved 

or adequate motor vehicle emissions budgets for that other 

NAAQS; and
Page 50 of 58

(2) the interim emissions tests as required by §93.119 

for one of the following areas: the portion of the 

nonattainment area not covered by the approved or adequate 

budgets for that other NAAQS; the entire nonattainment 

area; or the entire portion of the nonattainment area 

within an individual state, in the case where separate 

adequate or approved motor vehicle emissions budgets for 

that other NAAQS are established for each state of a multistate nonattainment or maintenance area. 

(B) The budget test as required by §93.118 for the 

entire nonattainment area using the approved or adequate 

motor vehicle emissions budgets for that other NAAQS.

(iv) If the nonattainment area partially covers an 

area for another NAAQS of the same pollutant:

(A) The budget test as required by §93.118 for the 

portion of the nonattainment area covered by the 

corresponding portion of the approved or adequate motor 

vehicle emissions budgets for that other NAAQS, where they 

can be reasonably identified through the interagency 

consultation process required by §93.105; and

(B) The interim emissions tests as required by 

§93.119, when applicable, for either: the portion of the 

nonattainment area not covered by the approved or adequate 

budgets for that other NAAQS; the entire nonattainment 
Page 51 of 58

area; or the entire portion of the nonattainment area 

within an individual state, in the case where separate 

adequate or approved motor vehicle emissions budgets for 

that other NAAQS are established for each state of a multistate nonattainment or maintenance area.

(3) In a nonattainment area, the interim emissions 

tests required by §93.119 must be satisfied for a NAAQS if

neither paragraph (c)(1) nor paragraph (c)(2) of this 

section applies for such NAAQS.

(4) An ozone nonattainment area must satisfy the 

interim emissions test for NOX, as required by §93.119, if 

the implementation plan or plan submission that is 

applicable for the purposes of conformity determinations is 

a 15% plan or other control strategy SIP that does not 

include a motor vehicle emissions budget for NOX. The 

implementation plan for an ozone NAAQS will be considered 

to establish a motor vehicle emissions budget for NOX if the 

implementation plan or plan submission contains an explicit 

NOX motor vehicle emissions budget that is intended to act 

as a ceiling on future NOX emissions, and the NOX motor 

vehicle emissions budget is a net reduction from NOX

emissions levels in the SIP’s baseline year.

(5) Notwithstanding paragraphs (c)(1), (c)(2), and 

(c)(3) of this section, nonattainment areas with clean data 
Page 52 of 58

for a NAAQS that have not submitted a maintenance plan and 

that EPA has determined are not subject to the Clean Air 

Act reasonable further progress and attainment 

demonstration requirements for that NAAQS must satisfy one 

of the following requirements:

(i) The budget test and/or interim emissions tests as 

required by §§93.118 and 93.119 as described in paragraphs 

(c)(2) and (c)(3) of this section;

(ii) The budget test as required by §93.118, using the 

adequate or approved motor vehicle emissions budgets in the 

submitted or applicable control strategy implementation 

plan for the NAAQS for which the area is designated 

nonattainment (subject to the timing requirements of 

paragraph (c)(1) of this section); or

(iii) The budget test as required by §93.118, using 

the motor vehicle emissions in the most recent year of 

attainment as motor vehicle emissions budgets, if the state 

or local air quality agency requests that the motor vehicle 

emissions in the most recent year of attainment be used as 

budgets, and EPA approves the request in the rulemaking 

that determines that the area has attained the NAAQS for 

which the area is designated nonattainment.

(6) For the PM10 NAAQS only, the interim emissions 

tests must be satisfied as required by §93.119 for 
Page 53 of 58

conformity determinations made if the submitted 

implementation plan revision for a PM10 nonattainment area 

is a demonstration of impracticability under CAA Section

189(a)(1)(B)(ii) and does not demonstrate attainment. 

(d) Hot-spot conformity test requirements for CO, 

PM2.5, and PM10 nonattainment and maintenance areas. This 

provision applies in accordance with §93.102(d) for a NAAQS 

and until the effective date of any revocation of such 

NAAQS for an area. In addition to the criteria listed in 

Table 1 in paragraph (b) of this section that are required 

to be satisfied at all times, project-level conformity 

determinations in CO, PM10, and PM2.5 nonattainment and 

maintenance areas must include a demonstration that the 

hot-spot tests for the applicable NAAQS are satisfied as 

described in the following:

(1) FHWA/FTA projects in CO nonattainment or 

maintenance areas must satisfy the hot-spot test required 

by §93.116(a) at all times. Until a CO attainment 

demonstration or maintenance plan is approved by EPA, 

FHWA/FTA projects must also satisfy the hot-spot test 

required by §93.116(b).

(2) FHWA/FTA projects in PM10 nonattainment or 

maintenance areas must satisfy the appropriate hot-spot 

test as required by §93.116(a).
Page 54 of 58

(3) FHWA/FTA projects in PM2.5 nonattainment or 

maintenance areas must satisfy the appropriate hot-spot 

test required by §93.116(a).

* * * * *

§93.116 [Amended]

5. Section 93.116(b) is amended by removing the citation 

“§93.109(f)(1)” and adding in its place the citation 

“§93.109(d)(1)”.

6. Section 93.118 is amended:

a. In paragraph (a), by removing the citation 

“§93.109(c) through (n)” and adding in its place 

the citation “§93.109(c) through (g)”; and 

b. By revising paragraph (b) introductory text.

§93.118 Criteria and procedures: Motor vehicle emissions 

budget.

* * * * *

(b) Consistency with the motor vehicle emissions 

budget(s) must be demonstrated for each year for which the 

applicable (and/or submitted) implementation plan 

specifically establishes a motor vehicle emissions 

budget(s), and for each year for which a regional emissions 

analysis is performed to fulfill the requirements in 

paragraph (d) of this section, as follows:

* * * * *
Page 55 of 58

7. Section 93.119 is amended as follows:

a. In paragraph (a), by removing the citation 

“§93.109(c) through (n)” and adding in its place 

the citation “§93.109(c) through (g)”; 

b. In paragraph (b) introductory text, by removing 

“1-hour ozone and 8-hour”;

c. By revising paragraphs (b)(1)(ii) and (b)(2)(ii); 

d. By revising paragraphs (c)(1)(ii) and (c)(2)(ii); 

e. In paragraph (d), 

i. By revising the heading of paragraph (d) to 

read “PM2.5, PM10, and NO2 areas.”;

ii. In paragraph (d) introductory text, by 

removing “PM10 and NO2” and adding in its place 

“PM2.5, PM10, and NO2”; 

iii. By revising paragraph (d)(2); 

f. By revising paragraph (e); and

g. In paragraph (g)(2), by removing “(b)(2)(i), 

(c)(2)(i), (d)(1), and (e)(1)” and adding in its 

place “(b)(2)(i), (c)(2)(i), and (d)(1)”.

§ 93.119 Criteria and procedures: Interim emissions in 

areas without motor vehicle emissions budgets.

(b) * * *

(1) * * *
Page 56 of 58

(ii) The emissions predicted in the “Action” scenario 

are lower than emissions in the baseline year for that 

NAAQS as described in paragraph (e) of this section by any 

nonzero amount. 

(2) * * * 

(ii) The emissions predicted in the “Action” scenario 

are not greater than emissions in the baseline year for 

that NAAQS as described in paragraph (e) of this section.

(c) * * *

(1) * * * 

(ii) The emissions predicted in the “Action” scenario 

are lower than emissions in the baseline year for that 

NAAQS as described in paragraph (e) of this section by any 

nonzero amount. 

(2) * * *

(ii) The emissions predicted in the “Action” scenario 

are not greater than emissions in the baseline year for 

that NAAQS as described in paragraph (e) of this section.

(d) * * *

(2) The emissions predicted in the “Action” scenario 

are not greater than emissions in the baseline year for 

that NAAQS as described in paragraph (e) of this section.

(e) Baseline year for various NAAQS. The baseline 

year is defined as follows: 
Page 57 of 58

(1) 1990, in areas designated nonattainment for the 

1990 CO NAAQS or the 1990 NO2 NAAQS.

(2) 1990, in areas designated nonattainment for the 

1990 PM10 NAAQS, unless the conformity implementation plan 

revision required by §51.390 of this chapter defines the 

baseline emissions for a PM10 area to be those occurring in 

a different calendar year for which a baseline emissions 

inventory was developed for the purpose of developing a 

control strategy implementation plan.

(3) 2002, in areas designated nonattainment for the 

1997 ozone NAAQS or 1997 PM2.5 NAAQS.

(4) The most recent year for which EPA’s Air Emission 

Reporting Rule (40 CFR Part 51, Subpart A) requires 

submission of on-road mobile source emissions inventories 

as of the effective date of designations, in areas 

designated nonattainment for a NAAQS that is promulgated 

after 1997. 

* * * * *

§93.121 [Amended]

8. Section 93.121 is amended:

a. In paragraph (b) introductory text, by removing 

the citation “§93.109(n)” and adding in its place 

the citation “§93.109(g)”.
Page 58 of 58

b. In paragraph (c) introductory text, by removing 

the citation “§93.109(l) or (m)” and adding in 

its place the citation “§93.109(e) or (f)”.