Ozone Is Dropping—Except in the Rural West

The Atlantic
Jason Plautz

The citizens’ group is now taking a data-driven approach to protecting their air, installing low-cost monitors around the region and building a record of pollution they hope can persuade researchers and regulators to take action before smog levels become more dangerous. But it’s not just Grand Junction: In 2013, an ozone monitor in Rangely, Colorado (population 2,400) spiked to more than 100 parts per billion (ppb), on par with levels measured in L.A. that same year. Over the past decade, monitors in the upper Green River Basin in Wyoming and the Uinta Basin in Utah have registered pollution levels above the Environmental Protection Agency’s health standards, and swaths of rural Texas have seen high ozone levels.

The phenomenon runs counter to national trends, which have seen ozone levels dropping steadily for decades. But a recent Tropospheric Ozone Assessment Report, which analyzed data from every available ozone monitor worldwide, found that in the Rocky Mountain region, nonurban areas are showing a slower decline than the rest of the country, with some regions even showing rising pollution. Rural monitors have also reported increases in southwestern Colorado and along the New Mexico–Texas border.

Ozone doesn’t come from any one source. Rather, it’s a mix of three ingredients: nitrogen-oxide pollution from motor vehicles, power plants, and industrial operations; volatile organic compounds (VOCs) from household products and other anthropogenic sources, as well as plants; and sunlight. Rural areas in the Far West have historically had fewer emission sources, and yet they have been seeing high ozone readings in the winter, when the air should be cooler and cleaner.

Seth Lyman, the director of Utah State University’s Bingham Entrepreneurship and Energy Research Center, studied the Uinta Basin and said one obvious culprit emerged: “We have nearly 100 percent certainty that oil and natural-gas development are the primary sources of the pollutants that make wintertime ozone,” Lyman said. “The mix of pollutants we measure in air in the Uinta Basin is the same mix that we know comes from the oil-and-gas industry.”

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