When winter comes to Utah and atmospheric conditions trap a soup of pollutants close to the ground, doctors say it turns every resident in the Salt Lake basin into the equivalent of a cigarette smoker.
For days or weeks at a time, an inversion layer in which high pressure systems can trap a roughly 1,300-foot-thick layer of cold air _ and the pollutants that build up inside it _ settles over the basin, leaving some people coughing and wheezing.
"There's no safe level of particulate matter you can breathe," said Salt Lake City anesthesiologist Cris Cowley, who is among a number of Utah doctors raising the alarm over some of the nation's worst wintertime air.
The doctors and a lobby group of Utah mothers are blaming a company that mines nearly a mile deep in the largest open pit in the world for contributing one-third of Salt Lake County's pollution. The rest is from tailpipe and other emissions.
They have filed a lawsuit against Kennecott Utah Copper, accusing it of violating the U.S. Clean Air Act. The company operates with the consent of state regulators who enforce the federal law.
The company is the No. 1 industrial air polluter along Utah's heavily populated 120-mile Wasatch Front and operates heavy trucks and power and smelter plants. It says the claims are "without merit."
Kennecott cites the blessing of Utah regulators for expanded operations and new controls that hold emissions steady.
Utah's chief air regulator, however, acknowledged Kennecott is technically violating a 1994 plan adopted by the U.S. Environmental Protection Agency that limited the company to hauling 150 million tons of ore a year out of the Bingham Canyon Mine.
Utah has twice allowed the company to exceed that limit, most recently to 260 million tons, as the company moves to expand a mine in the mountains west of Salt Lake City. In each case, Utah sought EPA's consent, but the EPA didn't take any action.
The lawsuit could force EPA's hand, said Bryce Bird, director of the Utah Division of Air Quality.
Bird said the old limit would defeat changes Kennecott made to curb dust and emissions since 1994.
The EPA rules that set production instead of emissions limits puts many companies in a similarly "awkward position" and undermines confidence in Utah's air pollution permits, Bird said.
Kennecott disputes the doctors' figure and says it contributes about 16 percent of Salt Lake County's overall emissions.
An examination by The Associated Press of emissions figures provided by Kennecott to state regulators shows the company's share of pollutants ranges from 65 percent of Salt Lake County's sulfur dioxide emissions to 18 percent of its particulates.
Particulates are tiny flecks of dust that doctors say can attract heavy metals. The particulates are ingested through the nose and lungs and can become lodged in brain tissue. They are especially damaging to the development of children.
Medical research has found that the first few minutes of exposure to air pollution does the most damage, with many people's bodies able to react and fight off longer bouts of exposure, the doctors said.
Yet exposure to dust, soot and gaseous chemicals constricts vessels and send blood pressure soaring, making some people's hearts flutter and spiking emergency hospital visits while putting fetuses in the womb at risk, the doctors say.
"Rio Tinto is making our blood vessels act as if they were seven years older," said Dr. Claron Alldredge, an opthamologist at LDS Hospital. "One year after returning to Utah after practicing elsewhere, I began to have high blood pressure myself."
Kennecott is a subsidiary of the international mining conglomerate Rio Tinto, which posts billions of dollars of profit a year and can afford to clean up its act, said Cherise Udell, founder of Utah Moms for Clean Air.
"This is not an attempt to shut down their mine," she said.
Kennecott said its takes improving air quality seriously, and Bird noted that while Kennecott is Salt Lake County's largest industrial source of air pollution, it has accomplished the largest reductions through better emissions controls.
"Kennecott has and continues to operate within the parameters of its air permits and is consistently in compliance with U.S. EPA and Utah Division of Air Quality regulations, which are based on strict standards for protecting human health," the company said.
The doctors are members of Utah Physicians for a Healthy Environment, which joined Udell's group in the lawsuit filed at Salt Lake City's federal court last week by lawyers for WildEarth Guardians of Santa Fe, N.M.