Ozone in Colorado mountains surprises researchers

DENVER — Researchers who examined air pollution along northern Colorado's Front Range said they were surprised by how much harmful ozone and ozone-causing chemicals are drifting into the mountains from urban and rural areas below.

"Really, all the way up to the Continental Divide you can find ozone," said Gabriele Pfister, a scientist at the National Center for Atmospheric Research in Boulder and one of the principal investigators on the project.

"People (are) thinking you go into the mountains and you breathe the fresh air — that's not always the case," she said in an interview Wednesday.

Researchers gathered data from aircraft, balloons and ground stations from the south Denver area to Fort Collins, about 60 miles to the north. The aircraft flights started in mid-July and ran until Aug. 18.

The scientists stressed they were in the very early stages of reviewing the data and were hesitant to offer many specifics.

Ozone can worsen breathing problems and damage crops and other vegetation. Oil and gas production, traffic, power plants and agriculture are among the major sources of chemicals that combine to create ozone when subjected to sunlight.

The Denver area sometimes exceeds federal standards for ozone, and the new data is expected to help lawmakers and regulators make decisions about bringing levels down.

Researchers said ozone and ozone-causing chemicals were pushed into the mountain air from lower elevations by wind and temperature-driven air movement.

Ozone was found in Rocky Mountain National Park about 60 miles northwest of Denver, said James Crawford, a research scientist at NASA Langley Research Center in Hampton, Virginia, and principal investigator for the space agency's part of the project.

"We view Rocky Mountain National Park as a refuge, and to learn there are days when it's not as safe as we think of it as, it's something people should know," Crawford said.

In some cases, the ozone levels in the mountains were similar to or greater than levels at lower elevations, said Frank Flocke, another NCAR scientist and a principal investigator.

Some ozone that is created at lower elevations filters to the ground or is diluted as air movement carries it into the mountains, but the precursors continue to produce more ozone as they rise, he said.

Aircraft detected ozone and precursors at 16,500 feet, Flocke said, more than 11,000 feet above Denver and more than 2,000 feet above Longs Peak, the highest point in the northern Rockies.

The consequences of mountain ozone still have to be examined and quantified, Pfister said. Flocke said ozone would have the same harmful effects in the mountains that it has at lower elevations.

The broader ramifications of the discovery are not yet clear. Two scientists with the Environmental Protection Agency didn't immediately return phone calls.

The researchers said they were fortunate to have both high- and low-ozone days during the study period.

"If it's dirty every day, you can't really get at it," Crawford said. "You want to look at a clean day versus a dirty day."

They expect to begin making their data public by the end of the year. They have so much that it will support years of research, Pfister said.

"I think it is a little bit overwhelming in a way, in a good way," she said.

Federal and state scientists and researchers from a dozen universities are participating in the research project.