(a) The Texas Natural Resource Conservation Commission (TNRCC) submitted to the EPA on June 17, 1994, a petition requesting that the Dallas ozone nonattainment area be exempted from the NOX control requirements of section 182(f) of the Clean Air Act (CAA) as amended in 1990. The Dallas nonattainment area consists of Dallas, Tarrant, Denton, and Collin counties. The exemption request was based on a photochemical grid modeling which shows that the Dallas nonattainment area would attain the National Ambient Air Quality Standards (NAAQS) for ozone by the CAA mandated deadline without the implementation of the additional NOX controls required under section 182(f). On November 21, 1994, the EPA conditionally approved this exemption request, conditioned upon the EPA approving the modeling portion of the Dallas attainment demonstration SIP.

(b) The TNRCC submitted to the EPA on June 17, 1994, a petition requesting that the El Paso ozone nonattainment area be exempted from the NOX control requirements of section 182(f) of the Clean Air Act (CAA) as amended in 1990. The El Paso nonattainment area consists of El Paso county, and shares a common airshed with Juarez, Mexico. The exemption request was based on a photochemical grid modeling which shows that the El Paso nonattainment area would attain the NAAQS for ozone by the CAA mandated deadline without the implementation of the additional NOX controls required under section 182(f), but for emissions emanating from Mexico. On November 21, 1994, the EPA conditionally approved this exemption request, conditioned upon the EPA approving the modeling portion of the El Paso attainment demonstration SIP.

(c) The Texas Natural Resource Conservation Commission submitted to the EPA on May 4, 1994, a petition requesting that the Victoria County incomplete data ozone nonattainment area be exempted from the requirement to meet the NOX provisions of the Federal transportation conformity rule. The exemption request was based on monitoring data which demonstrated that the National Ambient Air Quality Standard for ozone had been attained in this area for the 35 months prior to the petition, with the understanding that approval of the State's request would be contingent upon the collection of one additional month of data. The required additional month of verified data was submitted later and, together with the data submitted with the State's petition, demonstrated attainment of the NAAQS for 36 consecutive months. The EPA approved this exemption request on March 2, 1995.

(d) The TNRCC submitted to the EPA on August 17, 1994, with supplemental information submitted on August 31, 1994, and September 9, 1994, a petition requesting that the Houston and Beaumont ozone nonattainment areas be temporarily exempted from the NOX control requirements of section 182(f) of the CAA. The Houston nonattainment area consists of Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, and Waller counties. The Beaumont nonattainment area consists of Hardin, Jefferson, and Orange counties. The exemption request was based on photochemical grid modeling which shows that reductions in NOX would not contribute to attaining the ozone NAAQS. On April 12, 1995, the EPA approved the State's request for a temporary exemption. Approval of the temporary exemption waives the federal requirements for NOX Reasonably Available Control Technology (RACT), New Source Review (NSR), conformity, and vehicle inspection and maintenance (I/M) for the period of the temporary exemption. The temporary exemption automatically expires on December 31, 1996, without further notice from the EPA. Based on the rationale provided in the notice of proposed rulemaking on this action, upon the expiration of the temporary exemption, the requirements pertaining to NOX RACT, NSR, conformity, and I/M will again become applicable, except that the NOX RACT implementation date applicable to the Houston and Beaumont nonattainment areas under section 182(f) shall be as expeditious as practicable but no later than May 31, 1997, unless the State has received a permanent NOX exemption from the EPA prior to that time.

(e) The TNRCC submitted to EPA on March 6, 1996, a petition requesting that the Houston/Galveston and Beaumont/Port Arthur ozone nonattainment areas be granted an extension to a previously-granted temporary exemption from the NOX control requirements of sections 182(f) and 182(b) of the Clean Air Act. The temporary exemption was granted on April 19, 1995. The current petition is based on the need for more time to complete UAM to confirm the need for, and the extent of, NOX controls required. On May 23, 1997, EPA approved the State's request for an extension to the temporary exemption. The temporary extension automatically expires on December 31, 1997, without further notice from EPA. Upon expiration of the extension, the requirements pertaining to NOX RACT, NSR, I/M, general and transportation conformity will become applicable, except that the NOX RACT compliance date shall be implemented as expeditiously as practicable, but no later than May 31, 1999, unless the State has received a contingent NOX exemption from the EPA prior to that time.

(f) The extension of the temporary exemption from NOX control requirements of sections 182(f) and 182(b) of the Clean Air Act for the Houston/Galveston and Beaumont/Port Arthur ozone nonattainment areas granted on May 23, 1997, expired December 31, 1997. Upon expiration of the extension, the requirements pertaining to NOX RACT, NSR, I/M, general and transportation conformity will become applicable and the State is expected to implement the requirements as expeditiously as possible.

(g) The Texas Natural Resource Conservation Commission submitted a letter to EPA requesting rescission of the previously-granted conditional exemption from the NOX control requirements of section 182(f) of the Act for the Dallas/Fort Worth ozone nonattainment area. The letter was sent on November 13, 1998. The conditional exemption was granted on November 21, 1994, conditioned upon EPA approving the modeling portion of the DFW attainment demonstration SIP. The conditional exemption was also approved on a contingent basis. The modeling-based exemption would last only as long as the area's modeling continued to demonstrate attainment without the additional NOX reductions required by section 182(f). The State's request is based on new photochemical modeling which shows the need for NOX controls to help the area attain the ozone National Ambient Air Quality Standards. Furthermore, EPA would not and could not approve the earlier attainment demonstration SIP modeling upon which the condition was based.

(1) On June 21, 1999, the conditional NOX exemption for the DFW area granted on November 21, 1994 is rescinded. Upon rescission, the Federal requirements pertaining to NOX Reasonably Available Control Technology (RACT), New Source Review, vehicle Inspection/Maintenance, general and transportation conformity now apply.

(2) The NOX RACT final compliance date must be implemented as expeditiously as practicable, but no later than March 31, 2001.

[59 FR 60714, Nov. 28, 1994, as amended at 60 FR 5867, Jan. 31, 1995; 60 FR 19522, Apr. 19, 1995; 62 FR 28349, May 23, 1997; 63 FR 7072, Feb. 12, 1998; 64 FR 19286, Apr. 20, 1999]