Regulatory Announcement
 

Proposed Rule:
 

Transportation Conformity Rule:
 

PM2.5 and PM10 Amendments
 

The U.S. Environmental Protection Agency (EPA) is proposing 

changes to the transportation conformity rule that primarily 

concern conformity’s implementation in PM2.5 and PM10 nonattainment and maintenance areas. 

•	 EPA is proposing to update the transportation conformity 

regulation in light of the October 17, 2006, final rule that 

strengthened the 24-hour PM2.5 standard and revoked the 

annual PM10 standard. 

•	 EPA is also proposing to clarify the regulations concerning 

project-level air quality analyses to address a court’s remand of 

the transportation conformity hot-spot requirements for further 

explanation. 

This proposed rule would ensure that air quality is protected and 

would clarify requirements for implementers. 

EPA has worked closely with the U.S. Department of Transportation 

in the development of this proposed rule. 

Background 

Transportation conformity is a Clean Air Act requirement that ensures that federally 

supported highway and transit projects are consistent with state air quality implementation plans. Conformity helps protect public health through early consideration of the air quality impacts of transportation decisions in places where air quality 

does not currently meet federal standards or has not met them in the past. 

Office of Transportation and Air Quality 

EPA-420-F-09-005 

May 2009 
 

 

 

 

 

 

 

 

Regulatory Announcement
 

Key Elements of the Proposed Rule 

The proposed rule directly supports EPA’s broader strategy for implementing the revised 2006 

PM2.5 National Ambient Air Quality Standard (NAAQS). Providing clear guidance on how to 

implement transportation conformity under this NAAQS would ensure that transportation and 

air quality planning is coordinated and that clean air is achieved. 

The proposed rule describes when conformity first applies in 2006 PM2.5 nonattainment areas. 

The Clean Air Act and transportation conformity rule allow a one-year grace period before 

conformity applies for the revised NAAQS. This grace period begins upon the effective date of 

EPA’s nonattainment designation. 

The proposed rule also describes the general requirements for demonstrating conformity for the 

2006 PM2.5 NAAQS, including the regional emissions test(s) that would apply before and after 

SIP motor vehicle emissions budgets are established for the revised NAAQS. A motor vehicle 

emissions budget (or “budget”) is the level of emissions from cars and trucks that the state has 

determined to be consistent with local air quality goals. EPA is proposing that all 2006 PM2.5 

nonattainment areas without SIP budgets would have a choice of conformity emissions tests for 

ensuring that transportation decisions are consistent with clean air. Under the proposal, SIP 

budgets for the existing 1997 PM2.5 NAAQS would be used for conformity prior to establishing 2006 PM2.5 SIPs. Using existing 1997 PM2.5 SIP budgets in the interim would ensure that 

progress continues towards achieving the 2006 PM2.5 NAAQS. 

The proposed rule would update the baseline year for the interim emissions test in 2006 PM2.5 

nonattainment areas. EPA is seeking comment on several proposed options. 

The proposed rule would clarify which budgets PM10 nonattainment and maintenance areas 

would use for transportation conformity determinations, now that the annual PM10 standard 

has been revoked. 

The proposed rule would clarify that federally funded or approved highway and transit projects 

in PM2.5, PM10 and CO nonattainment and maintenance areas must not delay timely attainment or achievement of other interim milestones. 

Health and Environmental Benefits 

The proposed rule would improve the health and environmental benefits of the existing transportation conformity program. The proposed rule would ensure that new PM2.5 nonattainment 

areas and existing PM10 nonattainment and maintenance areas use conformity tests that ensure 

that air quality progress continues in areas that need to attain or maintain federal air quality 

standards. The proposed rule would also clarify that hot-spot analyses are performed in a manner consistent with the Clean Air Act’s public health and environmental requirements. 

Public Participation Opportunities 

We welcome your comments on this proposed rule. Comments will be accepted for 30 days 

beginning when this proposal is published in the Federal Register. 

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Regulatory Announcement
 

All comments should be identified by Docket ID No. EPA-HQ-OAR-2008-0540 and submitted 

by one of the following methods: 

• 	 Internet: www.regulations.gov 

• 	 E-mail: a-and-r-docket@epa.gov 

• 	 Fax: (202) 566-9744 

• 	 Mail: 


Air Docket, Environmental Protection Agency 


Mail Code: 2822T 


1200 Pennsylvania Avenue NW 


Washington, DC 20460 


• 	 Hand Delivery: 


EPA West Building 


EPA Docket Center (Room 3334) 


1301 Constitution Avenue NW 


Washington, D.C. 


If a public hearing is requested within ten days after publication of the proposed rule in the 

Federal Register, it will be held in Ann Arbor, Michigan approximately 20 days after publication 

of the proposed rule in the Federal Register. Additional information about the hearing will be 

printed in the Federal Register. Please see the proposed rule for additional information about the 

hearing. 

For More Information 

You can access documents on transportation conformity on EPA’s Office of Transportation and 

Air Quality Web site at: www.epa.gov/otaq/stateresources/transconf 

For further information on this proposed rule, please contact 

Laura Berry 

U.S. Environmental Protection Agency 

Office of Transportation and Air Quality 

2000 Traverwood Drive. 

Ann Arbor, MI 48105 

734-214-4858 

E-mail: berry.laura@epa.gov 

Or 

Patty Klavon 

U.S. Environmental Protection Agency 

Office of Transportation and Air Quality 

2000 Traverwood Drive. 

Ann Arbor, MI 48105 

734-214-4476 

E-mail: klavon.patty@epa.gov