A comprehensive analysis of emissions and ozone pollution in the Uintah Basin in eastern Utah concluded that the primary source is oil and gas operations.

The oil-field operations created about 99 percent of the volatile organic chemical emissions and about 70 percent of the nitrogen oxides emitted in the basin.

“It isn’t surprising, this is a rural area,” said Brock LeBaron, who managed the study for the Utah Department of Environmental Quality.

Across the West — from Colorado’s Front Range to Wyoming’s Green River Basin — oil and gas operations have been linked to ozone pollution.

Ozone pollution has become a problem in the Uintah Basin, with levels in 2011 reaching 139 parts per billion, nearly double the federal health standard. About 1,100 wells were drilled that year.

For the past three years, state and federal scientists have been collecting data in the basin and measuring emissions.

The area around Pinedale, Wyo., suffers from the same winter ozone problem.

As the Utah analysis continues, studies are underway by Colorado State University on the Western Slope, by the National Oceanic and Atmospheric Administration on the Front Range and by Wyoming state and university researchers in Pinedale.

“These studies are being driven in part by the ozone standard and in part by health complaints,” said Bruce Baizel, director the Durango-based Oil and Gas Accountability Project.

Leaks from pipes and tanks and fumes from pumps, dryers and compressors were major sources of volatile organics. Drill rigs and fracking were sources of nitrogen oxides and methane, according to the study.

The industry is already taking steps to curb many of the emissions, said Kathleen Sgamma, vice president for government affairs at the Western Energy Alliance, a trade group.

The industry is participating in the Uintah basin and Western Slope studies.

The federal Environmental Protection Agency put new rules in place last October requiring oil and gas operations to capture 95 percent of their emissions.

The EPA rule is similar to a regulation already in place in Colorado.

The Utah study stopped short of prescribing remedial steps.

Mark Jaffe: 303-954-1912, mjaffe@denverpost.com or twitter.com/bymarkjaffe