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Subject: New Guidance on CMAQ and Revocation of the 1-Hour Ozone Standard

James M. Shrouds
Director, Office of Natural and Human Environment

Joseph Ossi
FTA Acting Director, Office of Human and Natural Environment

FHWA Division Administrators
FHWA Directors of Field Services
FHWA Federal Lands Highway Division Engineers
FTA Regional Administrators

Date: December 13, 2004

Reply to: HEPN-10/TPE-30

This guidance addresses use of Congestion Mitigation and Air Quality Improvement (CMAQ) program funds in 1-hour ozone areas after the 1-hour ozone standard is revoked. This guidance replaces the section entitled "Revocation of the 1-Hour Ozone Standard" found on pp. 6-7 of the April 28, 1999, CMAQ Program Guidance.


Previous guidance allowed areas to update their Transportation Improvement Programs (TIPs) for a period of 4-months after the revocation of the 1-hour ozone standard. This guidance rescinds that provision. These areas may use the time up to the date of revocation (anticipated on June 15, 2005) to make any adjustments they feel are necessary to their TIPs. As noted below, nonattainment and maintenance areas that have their 1-hour ozone standard revoked may continue to fund the CMAQ projects directed at meeting the 1-hour standard included in the first 3 years of the TIP that is in existence at the time of the revocation. After the date of revocation, such projects may not be added to the TIP.

Areas in nonattainment/maintenance status for the 1-hour ozone standard at the time of revocation

This guidance examines project eligibility for areas that are nonattainment/maintenance for the 1-hour ozone standard. Unless designated for another pollutant, these areas will no longer meet the basic statutory requirement for CMAQ eligibility and will not be eligible to obligate CMAQ funds, except as follows.

CMAQ funds can continue to be obligated for projects that contribute to reduced emissions of ozone precursors included in the first 3 years of the TIP or State TIP that is in place at the time of revocation. CMAQ funds can also be used for projects that contribute to attaining the standard for other pollutants (CO, 8-hour ozone, PM2.5 or PM10) for which the area is designated nonattainment or maintenance. Alternatively, at the discretion of the State DOT, CMAQ funds can instead be redirected toward CMAQ projects in other areas within the State that are in nonattainment/maintenance status for CO, 8-hour ozone, PM2.5 or PM10.

The rules on "mandatory" and "flexible" CMAQ funds still apply, regardless of changes in 1-hour status. Aside from the exception noted in the paragraph above that allows areas to continue to fund projects that reduce ozone precursor emissions, mandatory CMAQ funds must be used for CMAQ projects in nonattainment/maintenance areas, if any exist. If no such areas exist in the State, the funds can be considered flexible, and can be used for CMAQ or STP type projects anywhere in the State. See p.5 of the 1999 CMAQ guidance for more information on programming "mandatory" and "flexible" funds. See Table 4, Part 2 Mandatory/Flexible Spending Amounts Pursuant to 23 USC 149(c) for TEA-21 to see the portion of CMAQ funds that is flexible by fiscal year (


As explained in 23 USC 104(b), CMAQ apportionments are calculated based on the populations of 1-hour ozone and CO nonattainment and maintenance areas only. One-hour ozone areas will no longer be included after the standard is revoked (except for the very few 1-hour maintenance Early Action Compact areas). Any changes to the CMAQ formula will be addressed following enactment of a reauthorization bill, assuming such bill adds PM2.5 and 8-hour ozone areas to the apportionment formula.

Updated: 09/23/2010
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