Denver Choking on Near Record Smog Levels

A hot morning sun shines down on a bike rider in Denver's Washington Park on Wednesday, July 19, 2006. For all its outdoor splendor and fit residents, the quality of Colorado's air this summer is hazy. Ozone levels along the heavily populated Front Range have been at extremes this summer. (AP Photo/Ed Andrieski) (Ed Andrieski - AP)

DENVER -- Colorado is suffering through a summer of smog.

With temperatures topping 100 degrees this month in Denver and elsewhere along the populous Front Range, routine activities like filling up at the gas station or mowing the lawn are releasing fumes into a perfect cauldron for creating ozone, a major component of smog.

Activists are sounding the alarm. Government officials are keeping watch. Nobody's breathing easy.

Denver is on a pace to eclipse the ozone-choked summer of 2003, the worst in 20 years, when the state issued 42 ozone alerts warning of unhealthy air. As of Wednesday, this summer has had 34.

Christopher Dann, a spokesman for the Colorado health department, said it's hard to point to one factor causing this summer's increase.

"There's no magic bullet out there that anyone can see," Dann said. "We're not out there generating ozone in great amounts, we're emitting precursor pollutants that are chemically changed in the atmosphere into ozone .... As long as human beings burn stuff, we're going to have pollution problems."

Ozone is created when the sun bakes common pollutants such as engine exhaust, wildfire smoke and vapors from everything from paint cans to oil and gas wells.

It's a particularly vexing problem for Denver, which vanquished its "brown cloud" in 2002 only to get tagged by the federal government two years later for missing new ozone standards.

While rebounding with acceptable ozone levels in 2004 and last year, this year's spike puts the region in jeopardy of coming under federal restrictions if it can't rein in the problem.

For most people, heavy ozone is only irritating, but for people with respiratory difficulties _ such as the more than 250,000 Coloradans with asthma _ it can lead to intense breathing problems, said Arthur McFarlane, who works with the state health department's asthma program.

The federal Environmental Protection Agency measures ozone at monitoring stations across the Front Range, using a complicated formula that allows for the effects of unusually hot weather.

If all-day smog ratings at any monitoring station, averaged over a three-year period, exceed the federal limit, the EPA can impose restrictions on the state, including limits on federal highway spending.