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Progress North Texas 2014


Air Quality, Transportation Closely Linked

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NCTCOG has been working on improving the air quality in the region for years. During this period, some standards were revoked and others were added to protect health. FWTAransportation Department has championed air quality planning efforts because almost 50 percent of ozone precursor emissions come from on-road vehicles. 

Ten North Texas counties1 are in nonattainment for the pollutant ozone under the Environmental Protection Agency’s 2008 National Ambient Air Quality Standard of less than or equal to 75 parts per billion (ppb)2. From 2006 to 2009, North Texas had great success in reducing ozone. The region’s design value decreased by 10 points, going from 96 ppb to 86 ppb. Since then, the design value has stayed relatively flat with slight increases and decreases over the past four years.

Air quality trends
The ozone level in the Dallas- Fort Worth area showed significant improvement between 2006 and 2009, but progress has stagnated recently. Planners have concluded that the average vehicle age, the increase of vehicle registrations and the decrease of AirCheckTexas funding in the 10 nonattainment counties, could be contributing to this trend.  

This stagnation raises several questions that are important to answer to continue the air quality success that were experienced until 2009. Why has the trend in reducing ozone stagnated? What is the key to reaching the 75 ppb standard by 2018, the region’s current attainment deadline? 

Specific trends yield insightful correlations. It is apparent transportation holds a significant stake in the success or failure of reducing ozone. What role do recent developments play? 


1. Slower rate of newer engine technology deployment 
Newer vehicle engines continue to pollute less over time due to federal regulations and new technologies.  However, since the global economic decline of the early 2000s, the average Dallas-Fort Worth vehicle fleet age has increased from seven to nine years old. Older vehicles emit more pollutants, leading to a greater difficulty in controlling emissions and reducing ozone. 

2. North Texas population and vehicle growth 
Since 2006, vehicle registrations in the 10-county nonattainment area have steadily increased. There is a growing number of vehicles – both overall and that are older – contributing to more roadway congestion, lower travel speeds and more exhaust emissions.  

3. 87 percent decrease in funding for reducing high-emitting vehicles 
Dedicated funding to support the AirCheckTexas Drive a Clean Machine program and Local Initiative Project funding significantly increased from 2006 to 2008, stayed steady from 2008 to 2011, then greatly decreased in 2012. Hence, the AirCheckTexas program has been hindered in its ability to assist in replacing old, high-emitting vehicles with newer, cleaner ones. From 2008 to 2011, AirCheckTexas replaced an average of approximately 6,600 high-emitting vehicles per year. After legislative budget cuts were made to the program, the average declined to approximately 1,300 for 2012 and 2013.


Drive a Clean Machine

With funding and programs such as these reduced, the challenge to decrease on-road vehicle emissions grows.  Though certainly not the complete answer to the question, these three points can offer insight as to why the region is struggling to get ozone trends back onto a downward slope.

Air quality trends
1 Those counties are Collin, Dallas, Denton, Ellis, Johnson, Kaufman, Parker, Rockwall, Tarrant and Wise. 
2 In 2008, the EPA revised the 8-hour ozone standard from the 1997 standard of 84 ppb to 75 ppb; the EPA finalized the designations under this new standard in 2012. Under this revised standard, the 10 counties have a December 31, 2018, attainment deadline. 
3 The fourth-highest 8-hour average ozone concentration averaged over a consecutive three-year period. Using the design value reduces the influence of unusual meteorological conditions in any given year, and more accurately reflects actual recurring pollution levels.   

What is the underlying key to reducing ozone? It is another question NCTCOG is working to solve. The answer lies in a combination of multiple efforts, of which every element is important. Here’s a snapshot of such efforts: 

Request for Information (RFI) – In December, NCTCOG issued an RFI to solicit emission-reduction control ideas including policies, projects, programs and technologies. If implemented, these could help minimize emissions from transportation sources. 

Legislation – Federal and state legislation, along with local ordinances, directly impacts air quality programs and may affect whether the region can reach attainment. Funding, rules and regulations adopted and enforced, as well as public support, play an important role in implementing control strategies that help improve air quality.  

Management and Operations – Many strategies are being implemented in an effort to help lower mobile source emissions. Examples are: expediting the use of advanced technologies, implementing demonstration programs to study the feasibility of control measures for possible region-wide deployment, recommending policies and providing support for other stakeholders who are implementing emission-reducing activities. 

Outreach – As policies, projects and programs are implemented to fulfill requirements under a variety of air quality mandates, strategic communication efforts are created and undertaken. They educate and inform the region on current air quality levels, associated impacts, strategies for improvement, funding opportunities and new programs and/or policies. For detailed descriptions of all air quality efforts and programs, visit  

It takes the cooperative work of a region to make the biggest impact. North Texas can meet the ozone standard and produce cleaner air for its residents if everyone does their part to make it happen. To learn more about what we’re doing as well as what you can do to join in on the effort to improve air quality, visit  

The contents of this report reflect the views of the authors who are responsible for the opinions, findings, and conclusions presented herein. The contents do not necessarily reflect the views or policies of the Federal Highway Administration, the Federal Transit Administration or the Texas Department of Transportation. This document was prepared in cooperation with the Texas Department of Transportation and the U.S. Department of Trasnportation, Federal Highway Administration and Federal Transit Administration.

4/24/2018 9/20/2013HC %Arc

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