Natural gas production in the Barnett Shale is contributing to higher ozone levels in the western Metroplex, according to a new study by the University of North Texas.
In a review of air quality data from 16 ozone monitors across North Texas, researchers found that although the region’s air has improved since 2000, it has not improved as much in the areas with gas production. Since 2008, ozone levels have risen across the region, part of national trend, but they have risen more in the North Texas counties with gas production, the study found.
The results were presented Thursday at a North Central Texas Council of Governments air quality meeting in Arlington. The research was performed by Mahdi Ahmadi, a graduate student in mechanical and energy engineering, studying under professor Kuruvilla John, associate dean of research and graduate studies in UNT’s College of Engineering.
“The overall trend in air quality has been improving. That’s the good news,” John said in an interview Friday.
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But, he said, “we found that when we compared the eastern half of the Metroplex to the western half, you see that in the Fort Worth and Denton area to the west, the reduction was not as prominent. The only difference is the shale play, or there are sources we are not accounting for.”
Based on the raw ozone data, the area without natural gas production, dubbed the “non-fracking region,” reduced the number of times it exceeded federal ozone standards about 4 percent more than the “fracking region.”
Fracking refers to hydraulic fracturing, a method of completing oil and gas wells, although the majority of emissions from oil and gas production take place after a well is completed.
John said a more worrisome finding came after adjusting the readings to eliminate weather-related factors such as temperature and wind, and looking at just the period after 2008, when ozone levels rose.
Ozone concentrations increased 12 percent during the summer in the fracking region, compared with 4 percent outside it, the study found. And during winter months, ozone levels rose 21 percent in the fracking region, compared with 5 percent outside it.
Ozone, or smog, is formed by the effect of sunlight on ozone precursors. Those include nitrogen oxides, commonly produced by automobiles, and volatile organic compounds, which come from a number of sources, including oil and gas production.
A 10-county area in North Texas is designated as an ozone non-attainment region by the U.S. Environmental Protection Agency. John said that higher ozone levels from natural gas production will make it harder for the entire region to come into compliance with EPA guidelines.
The Barnett Shale came to prominence after 2002 and by 2007 had become the nation’s largest natural gas producer. There were 17,494 wells in the field by the end of 2013, up from 5,720 in 2007, according to the UNT study.
In response to concerns about gas production’s effect on air quality, the Texas Commission on Environmental Quality has installed additional monitors to measure gas-related emissions. There are now a dozen of those devices, which sample the air hourly, in the area.
Those monitors are in addition to 20 monitors that measure ozone concentrations. Ahmadi took about 6 million points of data from 16 of those monitors, which had operated since 1997, for his study.
Ed Ireland, director of the Barnett Shale Energy Education Council, an industry group, said the study “is a modeling exercise based on assumptions that have yet to be revealed.”
John said Ahmadi’s study will undergo peer review for publication, which should produce feedback. He said the measurements from the ozone monitors provided strong data for the study.
Commission officials told WFAA/Channel 8 that they have asked for a copy of the UNT study but had not received it. When they do, officials said, they will evaluate the methodology and conclusions so they can review the work and comment accordingly.
State Rep. Lon Burnam, D-Fort Worth, worked to bring the study before COG as it works on a new smog-reduction plan for the Dallas-Fort Worth area by next summer.
“Until we start bringing these studies out, a lot of people are going to be in denial that we have a new set of problems to deal with,” Burnam told WFAA.