For the Mile High City, miles to go on smog

A veil of smog over Denver's skyline may not cause alarm; but when the dull gray haze settles over Rocky Mountain National Park, it's another story.

Last summer, air quality at the national park, 70 miles northwest of Denver, exceeded federal ozone standards seven times. Visitors, while admiring Continental Divide peaks soaring over 14,000 feet, breathed ozone concentrations above what's considered safe by the Environmental Protection Agency (EPA).

Now, the EPA is set to designate a huge swath of northern Colorado as a "non - attainment" zone under the Clean Air Act. Encompassing 11 counties in the Denver area, and the national park itself, the proposed region would span from Denver to Fort Collins, and eastward onto the plains. The tentative pollution-zone boundaries are unprecedented for Colorado, and signal a rising urgency to address growth and congestion here.

Ozone, a major component of smog, is a gas created when nitrogen oxides react with other chemicals in the atmosphere, especially in combination with sunlight. While there is no one source of ozone, automobiles and stationary combustion sources are seen as primary contributors.

Although the park doesn't generate significant ozone pollution, it receives dirty air produced in Colorado's densely populated Front Range. As the region registered repeated violations of the federal eight-hour ozone standard last summer, smog wafted into the park. "That has been a concern for the EPA and the National Park Service for some time," says Richard Long, director of the air and radiation program for the EPA's Region 8. "Ozone shows no deference to borders. It doesn't stop at the boundary of Rocky Mountain National Park."

Ozone pollution plagues a number of US cities - notably Los Angeles and Houston - and is considered a regional pollutant. On the East Coast, for example, it's seen as a multistate problem.

In a Dec. 3 letter to Colorado Gov. Bill Owens, the EPA noted that data from several Denver-area counties indicates that ozone standards are violated routinely. A number of factors are to blame - population density, traffic patterns, and the state's growing oil and gas industry - and justify expanding the official pollution zone, says Mr. Long.

The rise in smog is a major setback for Colorado. Little more than a year ago, Denver was being lauded for its success in clearing once-sooty skies.

The EPA at that time lifted the Mile High City's dirty-air label, declaring that it met national air-quality standards. For a city that, decades earlier, was among the nation's smoggiest, exceeding pollution standards 200 days per year, it was a tremendous feat, says Long.

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