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.
But that status was fleeting. By the time the EPA began enforcing stricter ozone standards last year, Denver was hovering at the brink of compliance. Last summer's violations weren't unexpected. Still, the record-high ozone levels were the worst since the mid-1980s. And their geographic range sparked alarm.
"There can be no clearer and more urgent call for comprehensive air-quality measures to protect Rocky Mountain National Park and the citizens of the Front Range," says Vickie Patton, a senior attorney with Environmental Defense's regional office in Boulder. "There is [an] imperative for action now."
State health officials agree. To stave off being cited a high-pollution zone again, Colorado is developing a proposal for reducing ozone levels by 2007. Under a pending agreement with the EPA, the state could avoid the legal restrictions that accompany nonattainment status.
The rub is that once the EPA approves a state proposal for reducing ozone, the city can't continue to violate federal standards. "The hammer is out there, it's cocked. If [Colorado] fails to meet the milestones, the hammer will fall," says Long
But the state isn't complaining. Having a conditional deferral of the pollution zone gives officials a chance to solve the problem independently, says Margie Perkins, director of the Air Quality Control Division for the state health department. "That way, we are allowed a little more flexibility in how we go about meeting requirements."
Under the state proposal - which is still being developed - cleaner-burning blended gasoline and emissions controls for oil-and-gas rigs would be mandatory. Coupled with technology advances in the coming fleet of automobiles, and tougher federal emissions standards for industry, ozone levels should decline significantly, state officials say.
"With these things that are already in the pipeline, we know we're going down in emissions," says Ms. Perkins.
Still, some believe that Colorado's efforts fall short of what's needed for lasting improvement, considering that Denver's population is projected to increase by 1 million in the next 20 years - a surge that places it among the country's fastest-growing regions. And the lack of a unified transit system only exacerbates Denver's infamous congestion - gridlock that makes it the third most congested city in the nation, according to the Texas Transportation Institute.
Reducing ozone concentrations to safe levels is achievable, says Patton. "But it's going to require some tough decisions."
Meanwhile, an expanded smog zone could spur state leaders toward more aggressive action, she says: "The nonattainment designation is really critical in two ways: First, in being honest and forthright with the public; and second, in putting in place a framework for policy solutions and control measures."