Air Quality

Helping Us All to Breathe Easy

As the number of vehicles on the nation’s roadways increased, air pollution from mobile sources was identified as an important national health concern. Recognizing this connection, the 1990 Clean Air Act Amendments (CAAAs) and the Tennessee and Mississippi Transportation Conformity Rules require the Transportation Improvement Program (TIP), and projects to conform to the purpose of the Tennessee and Mississippi State Implementation Plan (SIP). Conformity to a SIP means that planned transportation activities will not produce new air quality violations, worsen existing violations, or delay timely attainment of the National Ambient Air Quality Standards (NAAQS).

The Transportation Equity Act for the 21st Century (TEA-21) and its successor legislations, the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU), the Moving Ahead for Progress in the 21st Century (MAP-21), and most recently the Fixing America’s Surface Transportation (FAST) Act reinforce the need for coordinated transportation and air quality planning through the metropolitan planning process.

Currently, EPA designates Shelby County, Tennessee and DeSoto County, Mississippi as Attainment/Unclassifiable for the 2015 8-Hour Ozone NAAQS effective January 16, 2018 (Federal Register, Volume 82, Number 220 - 82 FR 54232).   There has been no ruling regarding the revocation of the Attainment/Maintenance area designation for Shelby and DeSoto County under the 2008 8-hour Ozone (O3) standard, therefore the Memphis MPO must demonstrate conformity for the 2008 8-hour ozone standard.  The transportation conformity requirements, under the Clean Air Act (CAA) section 176(c), for the Memphis MPO carbon monoxide (CO) maintenance area, ended on December 26, 2017. 

EPA Transportation Conformity Requirements for Carbon Monoxide (CO) Letter

For more information about project related conformity please visit the Regional Transportation Plan (RTP) and Transportation Improvement Program (TIP) webpages below;

FY 2017-2020 Transportation Improvement Program (TIP)

Livability 2040: Regional Transportation Plan (RTP)




Contact Us

Join our contact list.

Mailing Address:

125 North Main St., Suite 450

Memphis, TN 38103

Tel: (901) 636.7190

Fax: (901) 636.7272






  • This year:  378,915
Go to top