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Austin-Round Rock: Ozone History

Background and history of Austin-Round Rock (ARR) area compliance with the National Ambient Air Quality Standards (NAAQS) for ground-level ozone.

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2015 Eight-Hour Ozone Standard (2015 to Present)

On October 1, 2015, the United States Environmental Protection Agency (EPA) revised the primary and secondary eight-hour ozone standards to 0.070 parts per million (ppm). The 2015 eight-hour ozone NAAQS became effective on December 28, 2015 ( 80 FR 65292 ).

On November 16, 2017, the EPA designated the majority of Texas, including Travis, Williamson, Bastrop, Hays, and Caldwell Counties, as attainment/unclassifiable for the 2015 eight-hour ozone NAAQS, with an effective date of January 16, 2018 ( 82 FR 54232 ).

2008 Eight-Hour Ozone Standard (2008 to Present)

On March 27, 2008, the EPA revised the primary and secondary eight-hour ozone NAAQS to 0.075 ppm ( 73 FR 16436 ). On March 10, 2009, the governor recommended to the EPA that Travis County be designated nonattainment for the 2008 eight-hour ozone standard (see the governor's letter to EPA region 6 ).

In September 2009, the EPA announced it would reconsider the 2008 NAAQS and, on January 19, 2010, proposed to lower the primary ozone standard to a range of 0.060–0.070 ppm, and proposed a separate secondary standard based on cumulative seasonal average ozone concentrations. On September 2, 2011, President Obama announced that he had requested the EPA withdraw the proposed reconsidered ozone standard.

In a memo dated September 22, 2011 from EPA Assistant Administrator Gina McCarthy, the EPA announced that it would proceed with initial area designations under the 2008 eight-hour ozone standard, starting with the recommendations states made in 2009 and updating them with the most current, certified air quality data (2008 through 2010).

On May 21, 2012, the EPA published in the Federal Register final designations for the 2008 eight-hour ozone NAAQS ( 77 FR 30088 ). Travis, Williamson, Bastrop, Hays, and Caldwell Counties were designated attainment/unclassifiable under the 2008 eight-hour ozone NAAQS, effective July 20, 2012.

1997 Eight-Hour Ozone Standard (1997 to 2015)

Note: Effective April 6, 2015, the 1997 eight-hour ozone standard has been revoked in all areas, although some former 1997 eight-hour ozone nonattainment areas have continuing obligations to comply with the anti-backsliding requirements described in 40 CFR §51.1100(o).

In July 1997, the EPA announced a revised NAAQS for ground-level ozone. The EPA phased out and replaced the previous one-hour standard with an eight-hour standard to protect public health against longer exposure to this air pollutant. The EPA set the new eight-hour ozone standard at 0.08 ppm, which became effective on June 15, 2004, after several years of litigation.

The ARR area periodically measured exceedances of the 1997 eight-hour ozone standard following its promulgation. On December 18, 2002, local governments in the ARR area entered into a voluntary Early Action Compact (EAC) agreement with the TCEQ and the EPA to ensure that the area remained in attainment of the 1997 eight hour ozone standard. In 2003, the ARR area, working with the Capital Area Planning Council, the CLEAN AIR Force, the Greater Austin Chamber of Commerce, and other local organizations worked on developing and implementing an EAC plan. On March 31, 2004, a final plan was submitted to the TCEQ for incorporation into the state implementation plan (SIP). The Austin-area EAC included both voluntary and enforceable emissions-reduction strategies. Voluntary reductions focused on reducing the number of vehicles on ARR area roads because of the influence of vehicles on air pollution in the area.

On November 17, 2004, the commission adopted the Austin EAC SIP Revision , and at the request of the area adopted rule changes to 30 Texas Administrative Code (TAC) Chapters 114 and 115. The Austin EAC SIP revision consists of a 1997 eight-hour ozone attainment demonstration based on the EAC submitted to the TCEQ on March 31, 2004. This revision contains results of photochemical modeling and technical documentation in support of the attainment demonstration. The control strategies include rule revisions implementing a vehicle inspection and maintenance program in Travis and Williamson Counties, locally enforced idling restrictions, revisions to the volatile organic compound rules for degreasing, Stage I vapor recovery, and cutback asphalt use for all five counties in the ARR area. The control strategy for the area also includes locally implemented transportation emission reduction measures, enforceable commitments to reduce NOX emissions from power plants, and eligibility for Texas Emissions Reduction Plan (TERP) funding.

On June 18, 2008, the commission approved the Austin–Round Rock 1997 Eight-Hour Ozone Flex Plan and Memorandum of Agreement. Stakeholders involved in this plan are Bastrop, Caldwell, Hays, Travis, and Williamson counties; the cities of Austin, Bastrop, Elgin, Lockhart, Luling, Round Rock, and San Marcos; the TCEQ; and the EPA. The purpose of the Eight-Hour O3 Flex Program is to encourage eight-hour ozone attainment areas nationwide to reduce ozone emissions to continue to meet the NAAQS for ozone.

One-Hour Ozone Standard

Note: In 1997, the one-hour ozone standard was replaced by the more protective eight-hour ozone standard. The one-hour standard has been revoked in all areas, although some former one-hour ozone nonattainment areas have continuing obligations to comply with the anti-backsliding requirements described in 40 CFR §51.905(a).

Following the 1990 Amendments to the federal Clean Air Act, Austin and its surrounding counties were designated as attainment for the one-hour ozone standard. However, the ARR area sometimes monitored high ozone levels following its designation. On March 28, 2002, Austin area local governments signed a one-hour O3 flex agreement —a voluntary ozone-reduction plan—with the EPA and the TCEQ. The flex agreement was a plan for the area to address ozone problems and avoid a nonattainment designation.

Comprehensive History of the Texas SIP

This SIP History gives a broad overview of the SIP revisions that have been submitted to the EPA by the State of Texas. Some sections may be obsolete or superseded by new revisions but have been retained for the sake of historical completeness.