SAN ANTONIO — As San Antonio grapples with curbing a steady rise in ozone levels, state environmental officials are telling the Alamo City not to worry about how drilling in the Eagle Ford Shale is contributing to the problem.

Downplaying the impact of oil and gas drilling, Texas Commission on Environmental Quality Chairman Bryan Shaw emphasized repeatedly on Monday that the state wants to “strike a balance” between protecting the environment and business as it helps the city figure out what to do about its ozone levels.

The nation’s seventh-largest city is poised to become the last major city in Texas to be slapped with “nonattainment” status by the U.S. Environmental Protection Agency — and, with it, additional federal regulation and enforcement — because its ozone levels exceed the federal standard.

It was already on track to exceed the old limit of 75 parts per billion, which it had hovered below prior to 2012, according to the agency. When the Obama administration last month finalized a more-stringent 70 parts per billion maximum that San Antonio has not met in decades, it effectively guaranteed that the city would be found out of compliance.

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Any nonattainment designation for the city would come in late 2017, according to state officials. As local officials devise policies to curb ozone levels between now and then, the question of what is causing them to rise has become the subject of more research. 

A few years ago, a report by the Alamo Area Council of Governments suggested shale drilling played a sizable role in the city’s ozone creep — a connection local officials started looking into amid the now-dampened oil and gas boom.

But the council is expected to soon release another report suggesting that shale drilling now plays a smaller role in the city’s ozone levels, said Steven Smeltzer, the council's environmental manager. That's not because there is no causal connection between drilling and ozone-causing emissions such as nitrogen oxides, he said, but because the number of drilling rigs has dropped by more than half in recent years.

The real culprit in ozone pollution, though, has been traffic and tailpipe emissions, state environmental officials told local residents and organizations at an open house on the north side of town, making no mention of the drilling slowdown. 

“Emissions from oil and gas operations are sporadic; They’re localized in nature rather than widespread,” said Shaw, citing research he described as "preliminary." The agency is continuing to collect data on the issue, he said.

Asked whether the drilling slowdown played a role in lower ozone levels registered at a monitoring station closest to the 400-mile swath known as the Eagle Ford Shale, which brushes the southern tip of the San Antonio metropolitan area, Air Quality Division Director David Brymer said in an interview that numbers show it was on the decline even before that.

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San Antonio City Councilman Ron Nirenberg, who spoke Monday before Shaw and two other TCEQ commissioners, said in an interview that local research "increasingly points toward" activities such as shale drilling, energy production for the municipal electric utility and industrial activity like cement production — rather than cars and trucks — as the cause of rising ozone levels.

All contributing factors — including shale drilling — should be accounted for in what will have to be a multifaceted approach to improving air quality, he said. "Emissions reductions across the board are in our best interest," he said.

In keynote speeches Monday, Brymer and Michael Honeycutt, the head of TCEQ’s toxicology division, also presented research they said debunks the public health risks associated with higher levels of ozone — a pollutant known to worsen asthma, lung disease and heart conditions — while also contending that levels would improve even if the city did nothing.

“Your air quality is good and getting better,” said Honeycutt, whose presentation also touched on a decline in benzene levels and apparent inaccuracies of ozone monitoring.

A person would have to exercise vigorously for more than six hours in 95-degree weather with 72 parts per billion ozone levels before his or her ability to breathe would be impacted, Honeycutt explained in his presentation. Even then, he said, the effect on the ability to exhale would be minimal — 10 percent — and quickly would wear off after a period of rest.

TCEQ officials have not been shy in their opposition to the new federal ozone standards that San Antonio — with ozone levels of about 80 parts per billion — and every other major Texas city do not meet.

In 2013, the TCEQ hired an industry-friendly consulting firm, Massachusetts-based Gradient, to help it build a case questioning the public health benefits of reducing smog levels in the state’s big cities — benefits that the vast majority of experts say would be significant. (The agency recently renewed its contract with that firm, which now is also looking into the public health impacts of arsenic.)

Groups such as the American Heart Association and the American Academy of Pediatrics support even stricter ozone standards than the 70 parts per billion maximum that an EPA scientific panel unanimously approved last year. Standards were last lowered in 2008, the final year of George W. Bush’s presidency.

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Still, Shaw said in an interview he is determined to prove the EPA wrong on the new standard.

"There's a lot of data and analysis that would suggest that the (70 parts per billion) standard is more than protective," he said. "There's a lot of things that tell me that ozone is not causing the respiratory issues we have right now. And as long as we continue to think it's ozone, we're missing out on the opportunity to figure out what's really causing those respiratory issues."

That could be "some other emissions that we have that's in the ambient environment or, more likely, what I think is something that's either in our indoor environments — our workplace, our home. People spend 95 percent of their time indoors." 

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