State Perspectives on Regulating Background Ozone

On June 21, the Environment Subcommittee of the House Science, Space, and Technology Committee held a hearing on State Perspectives on Regulating Background Ozone. Among those called to testify was Diane Rath, executive director of the Alamo Area Council of Governments (AACOG) in San Antonio, Texas. She provided background on the great progress the San Antonio-New Braunfels Metropolitan Statistical Area (MSA) has made over the years in reducing ozone, and explained some of the complicated factors used to calculate the region’s ozone levels.

For AACOG and other regions facing variables outside of their control, federal ozone standards should be flexible enough to account for background ozone in trying to maintain healthy air quality for their citizens.

Regional Success in Reducing Ozone Levels

“The San Antonio-New Braunfels MSA has experienced significant improvement in its ozone levels in the last several years, with nearly a 20 percent decline in design value from 91 parts per billion (ppb) in 2004 to 73 ppb in 2016,” Ms. Rath noted in her testimony. “These improvements occurred despite a population increase of over 568,000 across the eight-county MSA during that period.”

When discussing what led to this drastic reduction in ozone levels, Ms. Rath stated that “the region’s success in improving ozone levels is due in large part to local voluntary public and private partnerships.” Some of the efforts noted in her written testimony included:

  • Bexar County and Cities of San Antonio, Leon Valley, and Seguin Anti-Idling Ordinances;
  • Participating in the Texas Emission Reduction Program (TERP) to facilitate turnover of older and dirtier diesel engines and engaging in community outreach to spread awareness of TERP among local industry and business leaders;
  • VIA Metropolitan Transit (VIA) began converting its diesel bus fleet to compressed natural gas (CNG) in April 2017 (VIA’s new CNG fueling facility is the largest in North America); and
  • Investments in the latest technology by both the energy industry in the Eagle Ford shale and the cement industry to reduce emissions.
Outside Influences on AACOG’s Ozone Levels

Improving the region’s ozone levels were complicated by multiple variables outside of AACOG’s control. According to Ms. Rath, tropical cyclones landfalling in the southeastern U.S. can cause spikes in local ozone levels, citing the example of Hurricane Irma as an instance where landfall in Florida triggered a high ozone event in San Antonio.

She also stated that “79.5 percent of San Antonio’s ozone is caused by emissions and transport from outside the San Antonio-New Braunfels MSA, that is, outside of local control.” The pie chart below used du

ring Ms. Rath’s opening testimony breaks down the contribution to San Antonio area ozone by geographic region.

background ozone

Questions from Congress

In response to questions from the Committee, Ms. Rath noted that San Antonio has taken aggressive actions to remain in attainment with the 2008 NAAQS. CPS Energy (a municipally-owned electric utility company) implemented cost-saving programs that resulted in savings equal to shutting down a medium-sized coal plant. CPS Energy produced 1500 megawatts of renewable energy capacity two years ahead of schedule, and are shutting down the Deely plant the region’s largest and oldest coal-powered plant.

The AACOG region faces a low estimate of over $117 million annually, and the high estimate is over $1 billion annually in economic consequences of a nonattainment designation. For every year we are in nonattainment, there is the potential for our eight-county MSA to incur over $1 billion in costs.

In addition, the impact of international ozone be taken into consideration when applying NAAQS to various regions in the U.S. How can you hold a community or region responsible for what is totally and completely outside of its control? Ms. Rath noted. If international transport was considered in measuring ozone levels, the region would be well under the limit.

Ms. Rath’s testimony and answers acknowledged the importance of the Environmental Protection Agency’s (EPA) National Ambient Air Quality Standards (NAAQS) for ozone but emphasized the adverse impacts of overly broad standards on regions, especially the San Antonio area. She urged Congress to “take advantage of the flexibility in the Clean Air Act to evaluate and actively consider during NAAQS designation the impact of background ozone levels and all foreign transport on a region.” This would be a step closer to ensuring that regional projects and economies don’t shoulder the full burden of nonattainment from factors outside their control.