In the ozone


In 2005, smog levels in Wyoming’s Upper Green River Basin surprised even the scientists who study one of smog’s primary components, ground level ozone. Ground level ozone is typically a summertime air pollution problem in traffic-ridden urban areas, like L.A., Salt Lake City and Denver. But in sparsely populated Sublette County, ozone that winter was nearly 25 percent above what the Environmental Protection Agency considers safe for human health. Since ozone levels there exceed federal standards, the EPA declared Sublette County a “nonattainment zone” for ozone which put the eye of the feds on the area and can bring stricter regulation.

Instead of hoards of traffic, Sublette County has oil and gas drilling. The gas itself releases volatile organic compounds and the diesel engines that run gas compressors emit nitrogen oxides—both of the pollutants form ozone when sunlight hits them. Along with Utah’s Uintah Basin it’s one of only two places known to have wintertime, instead of summer, spikes in ozone. Scientists have been working to untangle why these communities suffer from poor winter air quality, while other oil and gas regions may not. Until recently, there wasn’t even basic data on ozone levels in the two rural areas, and as Cally Carswell reported in her 2012 HCN story on the phenomenon, “Many years into a region-wide drilling boom, this points to an uneasy reality: Energy development has significantly outpaced our grasp of its effects on the environment and public health.”

But now, scientists are starting to answer the question of how it affects public health. The Wyoming Department of Health recently released a study linking elevated ozone levels in Sublette County to an increase in visits to local health clinic for problems like, asthma, bronchitis or respiratory infections. They funded the study after locals approached them with concern about air pollution, and found that for every 10 parts per billion increase in ground level ozone there was a three percent increase in the health clinic visits for respiratory problems (for reference, the EPA’s standard is 75 parts per billion).

Kerry Pride, a Center for Disease Control epidemiologist who works with the Wyoming health department, said that the results are in line with other studies of health impacts from ozone. She warned that people should keep in mind that children, the elderly or anyone who already has respiratory issues are going to be worse off. Wyoming’s Department of Environmental Quality provides winter ozone forecasting for Sublette County, so anyone who wants to go for a run or shovel snow on an elevated ozone day can think twice. “People need to remember that ozone, whether it’s in rural places or urban places can cause health effects,” she said.

Meanwhile, scientists are still trying to sort out what’s behind patterns of high wintertime ozone. Ozone formation is a finicky process, and understanding it depends on figuring out how volatile organic compounds and nitrogen oxides react with sunlight to form ozone at the ground. The ozone-chasing scientists that HCN covered last year recently released their results (pdf) from the 2011-2012 Uintah basin ozone study. They confirmed that light reflecting off snowpack plays a role, as does the weather, especially temperature inversions, which contribute to the stagnant air that keeps air pollution hanging around. But they are going to need more data before they can develop the kinds of ozone behavior models that big cities use to help manage their air pollution. Plus, what makes a perfect storm for the Uintah’s ozone may not be the same as what causes Sublette County’s to spike, so Wyoming is working to understand their unique ozone situation as well.

In the meantime, Wyoming’s environment department released an ozone reduction strategy last month. It includes short-term voluntary efforts by industry, better monitoring, and long-term rules to reduce emissions from oil and gas. “We can’t control the weather, but we can certainly work with the industry to reduce volatile organic compounds and nitrogen oxides,” said Keith Guille, a spokesperson for the Wyoming Department of Environmental Quality.

Sublette County and the Uintah Basin were caught off guard by ozone from their drilling frenzies, but hopefully even if drilling continues to grow, as a recent energy outlook suggests it will, there won’t be an excuse to bring bad air along with it.

Sarah Jane Keller is a High Country News intern.

Photo of Jonah Pinedale Anticline gas field in Wyoming’s Upper Green River Basin courtesy of NOAA.

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