People living within a half-mile of oil-and-gas well fracking operations were exposed to air pollutants five times above a federal hazard standard, according to a new Colorado study.

The University of Colorado-Denver School of Public Health analysis is one of a string of studies in Wyoming, Utah and eastern Colorado that highlight the air-quality impacts of drilling and hydraulic fracturing, or fracking.

"Our data show that it is important to include air pollution in the national dialogue on natural gas development that has focused largely on water," said Lisa McKenzie, the study's lead author.

The analysis found volatile organic chemicals five times above the federal Environmental Protection Agency's Hazard Index level at which there was little likelihood emissions would cause health problems.

The chemicals can have neurological or respiratory effects that include eye irritation, headaches, sore throat and difficulty breathing, the study said.

"We are seeing indications that oil and gas operations can release chemicals that can be harmful to residents," McKenzie said.

The study used three years of data around Battlement Mesa, where several companies are drilling, collected by Garfield County.

Advertisement

The findings add fuel to the debate in Colorado over how far wells must be set back from residential areas — an issue being reviewed by the Colorado Oil and Gas Conservation Commission.

The state requires a 150-foot setback in rural areas and a 350-foot setback in developed areas.

"This study raises questions about those setback standards," said Frank Smith, energy coordination for the non-profit Western Colorado Congress.

A state Assembly bill that would have raised setbacks to 1,000 feet died in committee in February.

Among the chemicals detected at elevated concentrations were trimethylbenzenes, aliaphatic hydrocarbons, and xylenes, the study said.

"The greatest health impact corresponds to the relatively short-term, but high emission, well completion period," the study said.

Completions involve fracking, a process in which water, sand and trace chemicals are forced down the well under pressure to crack the rock to release more oil and gas, and flowback, when the frack fluid and hydrocarbons return to the surface.

The study did not look at the full range of chemicals released from fracking operations, which also include diesel fumes and methane, or impacts beyond a half-mile, McKenzie said. More research needs to be done, she said.

"Members of the West Slope Colorado Oil & Gas Association concur with Ms. McKenzie's recommendations that additional study is needed," Davis Ludlam, the group's executive director, said in an email.

Ludlam noted that the industry is working with Colorado State University on an air-quality study.

"When good science justifies changing how we do business, our technology and know-how allow us to respond," Ludlam said.

The EPA is set to release new rules April 3 aimed at cutting emissions by 25 percent from oil fields by measures such as controlling for leaks and requiring green completions, which use no toxic chemicals.

"We've also seen studies from Texas showing high emissions from oil and gas fields," said Gwen Lachelt, director of the Durango-based Oil and Gas Accountability Project. "It is getting to the point that the industry has to be able to demonstrate their facilities aren't going to impact public health."

The UC-Denver study will be published in an upcoming edition of Science of the Total Environment.

Mark Jaffe: 303-954-1912 or mjaffe@denverpost.com