An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Texas, Houston/Galveston Area, Ozone, Post-1996 Rate-of-Progress Plan Summary

Texas Houston/Galveston Area Ozone Post-1996 Rate of Progress Plan

Purpose of Plan: To reduce emissions of Volatile Organic Compounds (VOCs) and Nitrogen Oxides (NOx) by 9% between 1996 and 1999.

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 nitrogen oxides (NOx))

The Houston/Galveston area (Houston) was designated “severe” for nonattainment of the ozone National Ambient Air Quality Standards (NAAQS).  Under the Clean Air Act, Houston was required to reduce emissions of ozone-forming VOCs by 15% between 1990 and 1996 - see Houston Ozone 15% ROP Plan summary.  After 1996 the state is required to further reduce emissions by 3% every year, averaged over three years, until the area attains the NAAQS.

States must submit, for EPA approval, a plan detailing how they will reduce emissions by 9% between 1996 and 1999.  This plan is referred to as the Post-1996 Rate of Progress plan, or the Post-1996 ROP plan.  Texas first submitted a Post-1996 ROP plan for Houston on November 9, 1994, with revisions August 9, 1996.  On March 9, 1998, the EPA proposed to disapprove the Houston Post-1996 ROP plan because the EPA believed Texas overestimated the amount of emissions reduction that would result from control measures in the plan.  On May 19, 1998, Texas submitted revisions to the Post-1996 ROP plan addressing the EPA’s concerns.

Pollution Data:
As required by the Clean Air Act, 1990 emission levels are used as a base from which to calculate emission reductions.  Texas submitted revisions to its 1990 base-year emissions inventory with its Post-1996 ROP plan, calculating that in 1990, Houston VOC emissions totaled 1064.85 tons per day and Houston NOx emissions totaled 1344.33 tons per day.  These numbers must be adjusted to exclude emissions reductions from federal regulations, such as the Federal Motor Vehicle Control Act, that were adopted before 1990.  The adjusted base year emissions inventory was 964.98 tons per day for VOCs and 1269.53 for NOx.  Accordingly, the target level in 1996 for VOCs was 812.77.  Houston’s 15% ROP plan was not required to include control of NOx.

Houston’s Post-1996 ROP plan includes reductions in both VOC and NOx emission levels.  The 1999 target level for VOCs was 772.08 tons per day and for NOx was 1191.77 tons per day.

Pollution Control Measures:
The Houston Post-1996 ROP plan included measures the state would use to achieve 9% emission reductions in the nonattainment area.  Some of these regulations were already included as part of the 15% ROP plan, but because the regulations require more stringent control measures to be implemented between 1996-1999, additional emission reductions could be credited to the Post-1996 ROP plan.  Furthermore, surplus emission reductions from existing control measures relied upon in the 15% ROP plan may be credited to the post-96 ROP plan.

In this table, 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

Federal Regulations

Regulation Description Date FR Citation
Hazardous Organic National Emission Standards Tightens controls on fugitive emissions from sources not covered under the Texas state law 4/22/1994 59 FR 19568
Airport Noise and Capacity Act of 1990 Requires cleaner aircraft with Stage III engines at most airports 9/25/1991 56 FR 48661
Spark-Engine Gasoline Marine Engines Controls emissions from outboard marine engines and personal watercraft 10/4/1996 61 FR 52087
New Non-Road Small Engines Controls emissions from lawn and garden equipment 6/3/1995 60 FR 34581
Tier I Motor Vehicle Control Program Tightens tailpipe emission standards on 1994 and later model light duty vehicles and trucks 7/5/1991 56 FR 25724
Municipal Solid Waste Landfills Tightens emission controls on existing landfills 3/12/1995 61 FR 9905
Pulp and Paper MACT Requires pulp and paper manufacturing facilities to meet Maximum Available Control Technology (MACT) standards 4/15/1998 63 FR 18504

Rule Effectiveness: Texas calculated additional emission reductions by demonstrating improved rule effectiveness for controls on floating roof tanks.  Rule effectiveness refers to the percentage of facilities in compliance with a given regulation.  

Transportation Control Measures: Houston’s Post-1996 ROP plan included local regulations that reduce emissions using transportation control measures such as traffic light timing improvements and high-occupancy vehicle lanes.

Underground Storage Tank Remediation: The Federal Resource Recovery and Conservation Act requires underground storage tanks to be upgraded with leak detection systems.  This will eliminate VOC emissions from leaks.

NOx RACT: Texas added sections 30 TAC 117.101-601 to its state code on June 9, 1993.  These regulations required facilities in non-attainment areas to implement all Reasonably Available Control Technology (RACT) to control NOx emissions.  The Texas NOx RACT includes an emissions cap program (30 TAC 117.223) and an emissions credits trading program (30 TAC 117.570).  

Contingency Measures:
Texas was required to submit contingency measures for Houston along with its Post-1996 ROP plan.  These contingency measures were to be triggered if Houston failed to meet its 1999 emissions reduction goal.  Contingency measures are required, if implemented, to further reduce emissions by 3%.  Houston’s contingency measures can reduce VOC emissions by 2% and NOx emissions by 1%.

VOC contingency measures

Regulation Description State Adoption EPA Approval date FR citation
30 TAC 115.442-449 Offset Lithographic Printing: regulates emissions from offset printing operations producing materials such as magazines, newspapers, and books 5/4/1994 5/22/1997 62 FR 27964
30 TAC 115.552 Dry Cleaning Naphtha:  controls emissions from dry cleaners that use petroleum naphtha 5/4/1994 5/22/1997 62 FR 27964
Spark-Engine Gasoline Marine Engines (2000) Controls emissions from outboard marine engines and personal watercraft.  Contingency reduction credit is taken from additional turnover of boats in the year 2000 Federal Regulation 10/4/1996 61 FR 52087
New Non-Road Small Engines (1999-2000) Controls emissions from lawn and garden equipment.  Contingency reduction credit is taken from availability of cleaner burning lawn equipment in 2000 Federal Regulation 6/3/1995 60 FR 34581
Phase II Reformulated Gasoline Tightens emission requirements on gasoline in certain areas beginning in 2000 Federal Regulation 2/16/1994 59 FR 7716

Houston’s VOC contingency measures also rely on surplus emission reductions from the required 9% ROP reduction.

NOx contingency measures
Houston’s NOx contingency measures include reductions from phase II reformulated gasoline regulations and surplus from the required 9% ROP reduction.

Subsequent Action and Events:
Post-1999 Rate of Progress Plans: (see Houston Ozone Post-1999 Rate of Progress Plans Summary)
The Post-1999 ROP plans reduce emissions in Houston by an additional 9% between 1999-2001, 9% between 2002-2005, and 6% between 2006-2007.  The EPA issued final approval of the Post-1999 ROP plans on November 14, 2001.

Attainment Demonstration:  (see Houston Ozone Attainment Demonstration Summary)
Texas submitted an attainment demonstration for the Houston ozone SIP, including modeling analysis projecting ozone levels in 2007 (Houston’s deadline for achieving NAAQS) and several enforceable commitments.  The EPA approved this attainment demonstration through parallel processing on November 14, 2001.

Texas had planned to fund TERP with taxes on out-of-state vehicle registrations, 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 state Governor June 22, 2003.

Federal Register Notices:

EPA Action Date Federal Register citation
Proposed conditional approval of Texas NOx RACT 10/28/1999 64 FR 58011
Final conditional approval of Texas NOx RACT 3/3/2000 65 FR 11469
Final approval of Texas NOx RACT 9/1/2000 65 FR 53172
Approval of revised motor vehicle inspection and maintenance program 11/14/2001 66 FR 57264
Proposed disapproval of 1994 Post-1996 ROP plan 3/9/1998 63 FR 11387
Direct final approval of 1998 Post-1996 ROP plan 4/25/2001 66 FR 20749


This SIP Citation Was Last Modified on: 08/15/2003