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Horse Pool, Uinta Basin • Sleuths prowled canyons and rangelands here this winter for clues about a big scientific mystery in the West's oil and gas lands.

Not so much a whodunit, their investigation has been more like a whatdunit. And, with one of the key suspects — typical winter weather — a no-show, the scientists have turned their attention to elusive, atomic-scale culprits — oxides of nitrogen, volatile organic compounds and oxidizing agents — and their sidekicks, the sun and wind.

"It's a kind of a detective story," said James Roberts, an ozone expert with the National Oceanographic and Atmospheric Administration (NOAA) Earth System Research Laboratory. "The mystery is what's causing high ozone, and the question is what do we need to do to control it."

Billions of dollars and thousands of jobs are on the line — not just in Utah but in the booming energy patches throughout the Mountain West.

That's where a growing body of evidence suggests a link between oil and gas production and surprisingly high levels of ground-level ozone, a pollutant that undermines the health of the sick and vulnerable and harms even healthy people who breathe it.

Normally considered a summertime pollutant in large cities such as Los Angeles and Houston, ozone pollution in the West's remote mountain valleys in the winter was discovered only a few years ago.

Solving the puzzle will make all the difference for people who live and work in the basin and those who count on the jobs and money the energy industry provides. No one — federal regulators included — wants to see needlessly expensive solutions to bring the air quality in line with Clean Air Act standards.

So local, state and national leaders, working with industry, mounted a $5.5 million study this winter to dig into the question: What exactly is causing the high winter ozone?

But there are many secondary questions to answer in what most agree is the biggest air-pollution study in Utah history.

They include: What role does snow cover play? Does the coal-fired Bonanza power plant nearby boost pollution levels? What impact do mountain elevation and sunshine have? And how much of the pollution-making chemicals comes from oil and gas mining?

NOAA, the Energy Dynamics Lab, Utah State University and the Utah Division of Air Quality, the U.S. Environmental Protection Agency, the University of Colorado, the U.S. Bureau of Land Management, the Uintah Impact Mitigation Special Service District and the Western Energy Alliance all are contributing to the study.

Investigative techniques they are using include a network of air-monitoring devices and giant balloons that take measurements up and down the air layers.

NOAA scientist Gabrielle Petron has been cruising the back roads of Uintah and Duchesne counties day and night with a specially equipped van, something like a scientific SWAT team command center to identify "fugitive" components of ozone-pollution chemistry.

"The chemistry itself needs to be shown," said Petron, a member of NOAA's global monitoring division.

The scientific team has many reasons to believe the ozone here is a lot more complex than the normal formula for the pollution. Roberts calls it "a different beast."

In a kind of atmospheric version of a CSI episode, he explored the problem from a remote village of trailers in the heart of the Uintah County gas patch called Horse Pool. His detective tools included one-of-a-kind instruments that record measurements every second, sometimes in fractions as small as parts per trillion.

Though his work focuses on atomic-size data, the answers could have a huge influence on smart solutions. For instance, when NOAA was working in Texas, what scientists learned about the ozone helped decision-makers switch strategies for controlling the pollution. The change averted a multibillion-dollar plan that would not have worked, Roberts said.

There's also hope that the Utah study could help other parts of the West that have seen similar trends.

A study last summer in Colorado found that ozone-forming air pollution from oil and gas fields was twice as bad as previously projected. And, in Wyoming, even after government oversight cut energy-industry emissions, ozone readings in the Upper Green River Basin sometimes rivaled levels seen in the summer in big cities.

Here at Horse Pool, Roberts is looking for a magic bullet for the basin.

Is it the off-the-charts high methane in the basin? That's one chemistry question he and fellow scientists are considering.

"Our mission," said the NOAA scientist, "is to find out what's happening so you can decide what to do."

The biggest complication has been this year's mild winter. Without the usual blanket of snow to bounce the pollution-making sunlight, ozone levels have been low. In fact, they did not reach the federal Clean Air Act standard of 75 parts per billion once this winter.

Last winter, they reached or exceeded the standard 25 times. And the winter before that it was 40, so the investigators already know the snow and inversions somehow play an important role.

"I guarantee you the snow didn't make ozone before the oil and gas came here," Roberts said

Even without the usual snow cover, inversions and bone-chilling cold, scientists have been pleased with the information they've gathered so far.

The silver lining might be that the levels measured this winter will be a good baseline, allowing for better comparisons once they come back and get data for a snowier, presumably more polluted year, said Scott Hill, director of the Energy Dynamics lab in Vernal.

"That will give us a lot of insights," he said.

Scientists working on this year's study have returned to their labs to analyze all the clues they've gathered through the winter. It will take months — perhaps more than a year — to publish their findings.

"We've learned a lot," said NOAA scientist Russ Schnell. "But we've just started to scratch the surface."

No doubt the results are eagerly awaited in the community.

Tom Elder, a high school science teacher in Vernal, said he hopes the study will produce some valuable answers and suggest solutions that will clean up the air without spurring a regulatory crackdown that could cost jobs and cripple the economic vitality as many fear.

"I do hope they follow the evidence to the truth regardless of what they find," he said, applauding the cooperative effort by the local, state and federal regulators and the energy industry. "The reason it came together is because they are scared spitless."

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