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Texas, Houston/Galveston Area, Ozone, Attainment Plan Summary

Texas Houston/Galveston Area Ozone Attainment Plan Summary

Purpose of Plan: To demonstrate that the Houston area will meet air quality standards by the attainment deadline of 2007.

Area Covered: Houston/Galveston area, Texas (Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, and Waller counties)

Type of Pollutant: Ozone (caused by reactions between VOCs and NOx)

The Houston/Galveston area (Houston) was designated as a nonattainment area for the 1-hour ozone standard under the Clean Air Act.  Houston was classified as "severe", giving Texas until November 15, 2007, to bring the area into attainment of the one-hour ozone NAAQS.  The Clean Air Act requires that states submit periodic Rate of Progress (ROP) plans to make sure nonattainment areas make continued progress toward attainment.  These ROP plans are submitted in the form of revisions to the State Implementation Plan (SIP).  The first of these ROP plans is the 15% ROP, requiring nonattainment areas to decrease ozone-causing emissions by 15% between 1990 and 1996.  After that, nonattainment areas are required to reduce emissions by 3% every year, averaged over 3 years, until the area reaches attainment.  (See Houston Ozone 15% ROP Plan Summary, Houston Ozone Post-1996 ROP Plan Summary, and Houston Ozone Post-1999 Plans Summary.)

The State is also required to submit an attainment demonstration showing how the Houston area will reach attainment by the 2007 deadline and including all emission control measures necessary for attainment.  Texas submitted its attainment demonstration SIP on May 19, 1998, with revisions November 15, 1999, December 20, 2000, May 30, 2001, and October 2001.  The attainment demonstration SIP identified emission reductions necessary to bring Houston into attainment by the 2007 deadline.  These reductions are to be achieved by a combination of adopted control measures and measures adopted pursuant to enforceable commitments.  (Please note that this is a brief summary of very complex Clean Air Act and SIP provisions.  Consult  the various SIP approvals and their supporting documents for a more detailed and in-depth analysis.)  EPA granted full approval of the Houston one-hour ozone attainment demonstration on November 14, 2001.

Pollution Data:
Texas used a photochemical grid model with a weight of evidence analysis (WOE) component to demonstrate attainment and selected September 8-11, 1993 as a base case episode because of its high ozone concentrations and weather patterns typical of high ozone episodes.  The base case was used to evaluate the model’s ability to reproduce actual monitored air quality values and predict air quality in the attainment year, and the model performed within EPA acceptable ranges.  Texas then generated projected emissions for the year 2007, and used the model with WOE to show that a total of 759.2 tons per day in NOx emissions are necessary to attain the standard by the deadline.

Pollution Control Measures:
The measures in the table below have been adopted by the state of Texas. The "Regulation" column displays the name or number of the regulation.  "FR citation" is the reference number for the Federal Register Notice announcing the EPA’s approval of those SIP revisions.  The Federal Register is an official government publication for rules and proposed rules of federal agencies.  It gives more detailed descriptions and explanations of the Houston SIP than are found here.  The first number represents the volume number - 59 represents the 1994 volume, 60 1995, and so on.  "FR" stands for federal register.  The number after "FR" is the page number.  
Federal Register notices can found at

Earlier Federal Registers can be found at Federal Depository libraries.

Control Measures

Regulation Description State Adoption EPA Approval into SIP FR citation
30 TAC 117 Major Point Sources:  Requires reductions in NOx emissions from Houston point sources 09/26/2001 11/14/2001 66 FR 57230
30 TAC 101.450-453 Inspection and Maintenance: requires annual inspection of motor vehicles in Houston for emissions violations – older cars undergo tailpipe testing, newer cars on-board diagnostic testing 12/6/2000 11/14/2001 66 FR 57261
30 TAC 114.312-319 Low Emission Diesel Fuel: Beginning April 1, 2005, all diesel fuel sold within the 110 counties listed (including Houston) must have no more than 10% aromatic hydrocarbons by volume, maximum of 500 ppm sulfur, and cetane number of 48 or greater 12/06/2000 11/14/2001 66 FR 57196
30 TAC 114.452-459 Small Spark Engine Operating Restrictions: Limits the use of small spark engines (25 hp and below) by commercial operators in Houston between 6 am and noon April 1 through October 31 12/20/2000 11/14/2001 66 FR 57223
Voluntary Mobile Emissions Program (local measure) Includes 14 separate voluntary measures to reduce emissions such as an alternative fuel program, public education, and a vehicle retirement program 09/26/2002 11/14/2002 67 FR 68941
Texas Senate Bill 5 Energy Efficiency: establishes energy efficient building codes and energy efficiency targets for state and local governments 09/26/2000 11/14/2001 66 FR 57159
Texas Senate Bill 5 Texas Emissions Reduction Program: provides incentives for reducing emissions from diesel equipment and purchasing of energy efficient cars 09/26/2000 11/14/2001 66 FR 57159
Speed Limit Reduction (local measure) Speed Limit Reductions: lowers speed limits in Houston that were above 55 miles per hour to 55 miles per hour beginning May 1, 2002 12/09/2000 11/14/2001 66 FR 57159
Agreed Orders 2000-0826-SIP and 2000-0827-SIP Airport GSE: Agreed orders for airport ground support equipment electrification with Continental Airlines and Southwest Airlines 10/18/2000; 12/06/2000 11/14/2001 66 FR 57222
30 TAC 114.420-429 Heavy Equipment Gas Engines: restricts emissions from non-road large spark-ignition engines. 04/19/2000 11/14/2001 66 FR 57219
30 TAC 117.471-479 Gas-fired Water Heaters, Small Boiler, and Process Heaters: reduces NOx emissions from small natural gas fueled water heaters, boilers, and process heaters 09/26/2001 11/14/2001 66 FR 57244
30 TAC 114.500-509 Vehicle Idling Restrictions: Limits idling of heavy duty motor vehicles in Houston to no more than five minutes between April 1 and October 31 12/20/2000 11/14/2001 66 FR 57223
30 TAC 117.206, 203, 475 Stationary Diesel Engines: Requires NOx emission reductions from stationary diesel engines and stationary duel-fuel engines in Houston beginning April 1, 2002 09/26/2001 11/14/2001 66 FR 57230
tation Control Measures  (local measure)
Transportation Control Measures: include measures such as HOV lanes, traffic signal timing improvements, and vanpools 12/09/2000 11/14/2001 66 FR 57159

The above measures represent some of the most stringent and comprehensive controls adopted anywhere in the nation.  Texas also relied upon federal on-road and non-road emission controls.  Taken together, these controls achieve 94 percent of the NOx reductions needed for attainment.  The final element of the State’s control strategy - which represents the remaining six percent (56 tons per day) of NOx reductions needed for attainment - is an enforceable commitment to adopt and implement additional NOx controls on a fixed schedule.  Texas provided EPA with a list of not-yet-available, cutting-edge, developing technologies and innovative ideas, with associated ranges of potential emissions reductions.  They include, for example, diesel emulsion, fuel cells, diesel NOx reduction systems, energy efficiency measures and several innovative ideas, such as marine loading operations and episodic emission controls.  The State also explained that, based on its analysis, the developing technologies and innovative ideas would achieve at least 56 tons per day of NOx emissions reductions, and perhaps as many as 123 tons per day. Because the committed-to remaining measures represent a limited portion of the overall emissions reductions needed, are on the cutting edge of technology but based on the State’s record should become available in sufficient time to be adopted and implemented by 2007, the commitment was for a reasonable and appropriate period of time and the State adopted such a comprehensive nature of control measures, the EPA determined that the State’s limited use of the enforceable commitment was appropriate.

Enforceable Commitments:
An enforceable commitment is a written commitment by the State, adopted after notice-and-comment and a public hearing,  to adopt and implement control measures in the future.  The State must also commit to submit the control measures as SIP revisions within specified timeframes.  These commitments can be enforced in court by both the EPA and affected citizens. Listed below are the enforceable commitments included in the Houston SIP attainment demonstration:

*  By May 1, 2004, perform and submit to the EPA as a SIP revision, a mid-course review evaluating the accuracy of the modeling analysis used in the attainment demonstration, and additional adopted control measures if determined to be necessary for attainment.

*  Perform new mobile emissions modeling using MOBILE6, EPA’s new on-road mobile emissions factor model, within 24 months of the release of MOBILE6.

*  Adopt rules that result in reduction of NOx emissions by at least an additional 56 tons per day - the amount needed to achieve ozone attainment levels.  These rules should be adopted and enforced as quickly as possible, but none of them shall require additional limits on highway construction.  Measures to achieve the first 25% of these reductions must be adopted and submitted to the EPA as a SIP revision by December 1, 2002.  Measures to achieve the remaining required reductions must be adopted and submitted as a SIP revision by May 1, 2004.  (This is the final element of the State’s control strategy which addresses the remaining 56 tons per day of NOx emission reductions needed to attain by 2007, as discussed in the previous section.)

*  If additional control measures reduce the Motor Vehicle Emissions Budget, submit to the EPA those reductions as revisions to the attainment demonstration.

Subsequent Action and Events:
Texas had planned to fund TERP with taxes on out-of-state vehicle registrations, but this tax was found to be unconstitutional in February of 2002, leaving Texas without the funds it needed to achieve the projected emission reductions.  In August of 2002, the EPA proposed to find that Texas was not complying with the terms of the attainment demonstration.  However, funding for TERP was restored by Texas House Bill 1365, signed by the Governor June 22, 2003.  The TERP program’s methodology was adopted and submitted to EPA for approval in a December 2002 HGA SIP.  In this 2002 revision, the TCEQ identified the TERP program as meeting the enforceable commitment to achieve the first 25% of  the NOx reductions.  EPA will publish action in a Federal Register notice, and provide an opportunity for comment.  

The TCEQ provided an additional enforceable commitment which EPA approved on November 14, 2002.  This was an enforceable commitment to “backfill” any emission reductions not achieved by the SIP-approved VMEP plan.

Federal Register Actions:

EPA Action Date Federal Register citation
Proposed conditional approval of one-hour attainment demonstration 12/16/1999 64 FR 70548
Proposed approval of one-hour attainment demonstration 07/12/2001 66 FR 36655
Final approval of one-hour attainment demonstration 11/14/2001 66 FR 57159
Final approval of revisions to speed limit and VMEP 11/14/2002 67 FR 68941
Proposed finding of failure to implement Houston ozone SIP 08/01/2002 67 FR 49895

This SIP Citation Was Last Modified on: 08/14/2003