By Berny Morson
and Deborah Frazier
Denver Rocky Mountain News Staff Writers

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The brown cloud -- a pall of dust and other airborne particulates smudges Dener's skyline in 1996. The city has made important strides in reducing smog that once threatened public health.

A cloud of black smoke billowing from a steam locomotive symbolized progress in 1870, when the railroad linked Denver to the world.

By the mid-20th century, however, Denver residents had become profoundly concerned about smoke from railroads, cars, factories and garbage burning in backyard incinerators.

"I can remember my parents talking about it," recalls Steve Arnold, head of the state health department's air pollution division. "My parents (were) saying, 'I don't ever remember that it looked so bad out there all the time. It just seems that air pollution -- whatever that is -- is getting worse."'

By the 1970s, the pollution hanging over the city had a name -- the brown cloud. And efforts to get rid of it -- as well as less visible pollutants such as carbon monoxide -- became a crusade for Coloradans in the last three decades, winning wide support in poll after poll.

Clean air long had been an important reason people moved to Colorado, even in the 19th century.

By 1900, about 25,000 Denver residents, about a fifth of the population, were pulmonary patients who had moved to the city for the air. They were dubbed "the one-lung army."

But Denver's location at the foot of the Rocky Mountains made it prone to temperature inversions in which warm air traps cooler air near the ground, preventing pollutants from dispersing.

As Denver industrialized, a vile brew of coal smoke from thousands of residential and industrial furnaces besmirched the mountain view. A forest of smokestacks marked the smelters and factories stretching along the South Platte River.

"Throughout the day, the chimneys of the big office buildings and factories pour out tremendous clouds of impenetrable and offensive black smoke, which rapidly spread their inky filth over the business blocks, sift through the windows of offices and smut the faces of pedestrians," The Denver Times newspaper reported on July 11, 1898.

Unfettered by the filters and scrubbers of today, coal furnaces lit the city, warmed homes and businesses, generated steam for fabric mills, cooked gold, silver and lead from ore and propelled steam engines along a dozen major rail lines.

Few streets were paved, adding dust to the messy air. And in 1900, the first car appeared in town, portending more air problems.

The Denver Chamber of Commerce ignored the foul air and campaigned for more factories with promises of pure air, mountain breezes and cheap coal.

But not everyone bought the hype. The Denver Times, on July 2, 1889, noted that disease had started to spread to the entire population. Pollution was to blame, the newspaper said, and the bad air was hurting the city's reputation.

"The bright, sunny Colorado days, famous all over the world, are not to be seen in the city these days and tourists hurry away as fast as possible," the Times said in the unattributed style of the day.

By the mid-1950s, health officials were becoming alarmed.

"The number of communities that consider themselves confronted with an atmospheric pollution problem has been rising steadily, particularly in the last 10 years," said a 1957 report prepared by the U.S. Public Health Service and the Denver Department of Health and Hospitals.

Health professionals weren't alone in their worries. The city logged 1,250 air pollution complaints in 1956 from citizens about excessive smoke or other air problems.

Concentrations of carbon monoxide grew to potentially deadly levels in the late 1960s. On Nov. 20, 1968, the state health department's downtown monitor recorded a carbon monoxide level of 79 parts per million, more than twice the standard allowed today by the Environmental Protection Agency. On other days, mobile monitoring devices found levels of 140 parts per million on some heavily traveled roads.

Studies at the time showed that heart patients began to suffer when carbon monoxide levels reach 50 to 100 parts per million.

By the early 1970s, the public was becoming alarmed about a host of environmental problems, says former state Sen. John Bermingham, R-Denver.

In 1970, the legislature adopted the massive Air Pollution Control Act, with Bermingham as the chief Senate sponsor.

The law authorized preparation of a plan to control air pollution. And it gave the governor a power that today seems almost unimaginable -- the authority to halt all traffic and shut down factories whenever carbon monoxide reached dangerous levels.

Despite the tough language about smog, few people believed pollution would decline.

"I was one of them," says Arnold, the health department air chief, who joined the agency in 1971. "It seemed impossible to do."

For awhile, the skeptics were right.

Denver exceeded the federal carbon monoxide standard 154 times during the peak year of 1972.

Health department officials were on the phone with the governor's office on Nov. 21, 1974, when carbon monoxide reached 70 parts per million -- the level at which the governor could halt all traffic and industry.

That step wasn't taken because the forecast called for weather that would carry the pollution away, Arnold says. But industry leaders were asked to voluntarily halt unnecessary emissions.

Under pressure from the EPA, the state began drafting a plan to improve air quality in 1977. By the mid-1980s, the legislature -- with bipartisan support -- had passed laws mandating oxygenated fuels in winter months, maintenance inspections and wood-burning bans on high-pollution days.

A great ally in the pollution fight was technology. Cars today emit only a fraction of the pollution given off 15 years ago.

Denver now meets the carbon monoxide standard -- a rare lapse occurred Nov. 30 -- though the brown cloud, which sparked public concern in the first place, often is as visible as ever.

That's because the city continues to expand outward, Arnold says.

It's not that the air is more polluted, he explains. The brown cloud is caused by tiny particles, not carbon monoxide. And people's vision of the mountains is being filtered through more miles of dirty air.

New monitoring equipment was installed this year, but improvement could be years away.

Colorado Milestones, which appears Tuesdays, is part of a yearlong project by the Denver Rocky Mountain News, NEWS4 and the Colorado Historical Society. Digital and print copies of historical images available at the Colorado Historical Society (303) 866-2305.

Online: RockyMountainNews.com, keyword 2000.

On TV: Sunday at 10 p.m.: Colorado History: Boom and bust and boom again -- so goes Colorado's economy.

December 7, 1999

Colorado Millennium 2000 is a yearlong project by the Denver Rocky Mountain News, NEWS4 and the Colorado Historical Society
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