Making his descent from the mountaintop Thursday morning, bicyclist Kent Bell rolled smack into the filmy haze coating this resort town. Forty miles away, near Friday’s finish line of the Ride the Rockies endurance test, one of the largest fires in Colorado history raged out of control.

Over the last few days, insulated by clear skies to the west, the 36-year-old rider had heard there was a wildfire somewhere out in the forest, but he wasn’t sure where. Then he saw the smoke.

“It was a shock. Coming down you first see this shroud,” he said. While Bell was confident his lungs would hold out as the race pressed closer to the vast burn area, he worried about the riders behind him.

Like Bell, those cyclists only have to look toward the heavens to see what confronts them. Across the face of the Rocky Mountains’ majestic front range, stinging smoke and ash have blurred the horizon, burned throats and canceled outdoor events.


Officials worry that the mammoth High Park blaze -- now only 10% contained -- could burn all summer, devastating not only the state’s air and water quality, but also its $10-billion annual tourism industry.

Since last weekend, the High Park fire has churned through 78 square miles of forestland, destroyed scores of homes and taken one life. But the blaze -- and its thick smoke plume soaring 34,000 feet into the sky -- is menacing residents miles away in Denver, Colorado Springs and other communities, altering the outdoor aesthetic in one of the nation’s most athletically active states.

The smoke and ash have affected runners, walkers, cyclists, fishermen, swimmers, kayakers and hikers -- threatening to sentence a population used to exercising under the summer sun to an indoor fate.

The state Department of Public Health and Environment has warned the public to avoid outdoor activities as windblown particulates blanket a 150-mile stripe from the Wyoming border to Colorado Springs.


“It’s certainly a challenge in a state like Colorado, which has a real outdoors ethic,” said Christopher Dann, public information officer for the Colorado Air Pollution Control Division. Dann has fielded dozens of calls from concerned citizens, including day care operators in Denver more than 60 miles from the fire, asking if it is safe to let children play outside.

Answer: Depending on the wind and time of day, maybe not.

The High Park fire, the third-largest wildfire in state history, has 1,200 firefighters working around the clock. Colorado Gov. John Hickenlooper declared a state of disaster, allotting $20 million in state funding and the use of the Colorado National Guard.

In Denver and other areas -- where the air sometimes carries the acrid whiff of a campground -- news of the fire has hijacked newspapers and TV bulletins, not to mention conversations at grocery stores, offices and gyms.


In Fort Collins, just east of the fire, ash has coated cars and filled sidewalk cracks. The city’s pool closed for the first time in recent memory, a Father’s Day 5K run has been postponed and activities for seniors and children have been canceled or moved indoors -- including a youth football camp now holding its scrimmages in a former dance hall.

Fourteen miles to the south in Loveland, children’s swim lessons and sports camps have also been canceled for the first time due to a wildfire. “The whole Front Range is a tinderbox,” said Kevin Aggers, recreation division manager in Loveland. “No one is complaining. There are more important things than a swim lesson.”

At Water World, a suburban Denver theme park, the smell of smoke Tuesday trumped that of chlorine, prompting at least one parent to ask operators if it was safe to leave her children.

Miles away, an outdoor outfitter near Fort Collins has had to cancel a dozen rafting and fly fishing trips, and operators worry that even after the fire is out, people may stay away.


The route of the Ride the Rockies Bicycle Tour is being shortened and diverted farther east because some roads along the original route have been closed by the blaze.

The ride, a six-day international event in which 2,000 riders cover 442 miles, scaling five mountain passes, was scheduled to finish Friday. Officials said worsening air quality may prompt some cyclists to take a shuttle to the finish line rather than brave the elements.

The arts have suffered has well. The Mishawaka Amphitheatre in rural Bellvue has canceled outdoor concerts by Bruce Hornsby and others through next weekend.

And effects may continue even after the fire is out, which could be months from now. Greeley and many other communities get their water from the burn area, and officials worry about residual ash washing into the city’s water in coming months.


The size and threat of the High Park blaze reminds many Coloradans of the infamous 2002 Hayman fire, which threatened much of the state. Peering down from an airplane, a stunned Gov. Bill Owens observed that the yellowish smoke “looks like nuclear winter.”

Fallout from the current fire has concerned scientists even outside Colorado. Each year in the U.S., forest fires burn an average of 5 million acres, taking lives and property. But experts say diminished air quality from such blazes carries distinct health risks.

How much gas and pollution a fire spews can depend on the kinds of trees consumed, air temperatures and the extent of brush and other fuel on the ground. Scientists with the nation’s Environmental Protection Agency are studying the pollution role of blazes such as the High Park fire amid hotter temperatures due to global climate change.

“Fire damage goes beyond burned homes or lives taken,” said Bob Yokelson, a chemist at the University of Montana who specializes in climate change. “In the summer, one-third of the pollution we face may be caused by fires.”


And controlling both the cause and fallout of many fires remains elusive. “The government can set standards on auto or power plant pollution,” said Jennifer Logan, a Harvard University atmospheric chemist, “but you can’t control what comes out of a fire.”

In Colorado, Greg Streech has devised his own brand of damage control. The Denver-area resident noticed ash on his deck last weekend. Since then, the particles have wreaked havoc on his allergies.

So the avid mountain biker has traded the great outdoors for his basement and a spin bike. “I’m staying indoors,” he said.

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john.glionna@latimes.com

Special correspondent Deam reported from Colorado and Glionna from Las Vegas.