Photo ©iStockphoto.com/Andrew Dean.
Despite living in one of the fastest growing metropolitan areas in the nation, the more than six-million residents that call the Dallas–Fort Worth (DFW) area home are breathing cleaner air than they were ten, or even five, years ago.
In 2008, for example, the area—which includes Collin, Dallas, Denton, Tarrant, Ellis, Kaufman, Johnson, Parker, and Rockwall counties—measured the lowest levels of ozone in three decades. Ozone readings, which had been at more than 100 parts per billion (ppb) a few years prior, fell to 85 ppb. Design values—statistics that describe the air quality status of a given area relative to the level of the National Ambient Air Quality Standards (NAAQS)—decreased by 16 percent from 2000 to 2009. The area currently has a design value of 86 ppb. Additionally, ozone levels only exceeded the health-based standard of 84 ppb for nine days during the summer of 2008 and 12 days during the summer of 2009, compared to over 40 days in the late 1990s. The DFW area has also been in compliance since 2006 with the previous one-hour ozone standard of 124 ppb.
Control Strategies Reduce NOx Emissions
About 75 percent of the DFW area’s NOx emissions—such as from on-road mobile sources (cars and trucks) and nonroad mobile sources (construction equipment, aircraft, and locomotives)—are under federal jurisdiction. The state, however, has achieved substantial NOx reductions through regulation of point and area source emissions, which make up 22 percent of NOx emission sources. The remaining three percent of NOx emissions is from natural sources, such as microbial soil emissions.
Control strategies adopted by the TCEQ for stationary sources include strict air pollution rules inside the DFW area, which require NOx reductions from power plants, cement kilns, and other major and minor industrial, commercial, and institutional sources. Rules also require NOx reductions from stationary rich-burn, gas-fired internal-combustion engines in 33 attainment counties east and southeast of the area.
TCEQ Initiatives Reduce Ozone Emissions
Hundreds of lane-miles of freeways and interstates move hundreds of thousands of vehicles each year throughout the region. Because transportation-related activities account for nearly one-half of all ozone-causing pollution, the TCEQ has collaborated with local businesses, governments, and communities to implement programs that target mobile-source emissions for reduction.
Two TCEQ programs established by the Texas Legislature have been especially effective. They are the Texas Emissions Reduction Plan (TERP), which was created to reduce emissions from heavy-duty on-road vehicles and nonroad equipment, and the Drive a Clean Machine program, which was initiated as a way to replace older, polluting vehicles with newer, cleaner-running vehicles. (See “TCEQ Programs are Key to State’s Success,” for more about these two programs.)
Fleet turnover has also been a major contributor to getting older vehicles off the road. Furthermore, residents in the DFW area are required to submit their cars for strict emissions-control inspections.
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