Cheryl Heying, of the Utah Division of Air Quality, said the new pollution standards are certain to mean more EPA oversight for the mountain basins of northern Utah, which suffer high levels of PM (particulate matter) 2.5 during wintertime inversions.
"There is a good probability we will exceed those [proposed EPA] standards," she said.
PM 2.5 is basically made up of soot from combustion, chemically stewed in the air and transformed into particles about one-fortieth the diameter of a human hair. The particles penetrate lung tissue and are blamed for a growing list of lung, heart and other health problems, including cancer.
For many Utahns, when an inversion sets in and traps wintertime pollution, high PM 2.5 levels lead to a scratchy throat, a cough and tightness in the chest. For the very young, the old and people with heart and lung ailments, it means watching for health advisories and limiting exertion outdoors to avoid serious harm.
EPA Administrator Steve Johnson told reporters his decisions were based on "the best science available to date . . . particularly for the most vulnerable among us." And he would not elaborate when asked why he did not opt for the even tougher standards recommended by the agency's science advisers.
This is the EPA's second-generation standard for PM 2.5, and a federal court has determined it must be made final by September. The current standard went to the Supreme Court and is only now being implemented by affected states.
Federal regulators look at levels of PM 2.5 in the air in two ways, a yearly average and a daily average. The annual average of 15 micrograms of PM 2.5 per cubic meter of air will stay the same, under the proposed regulation.
But the daily average standard will drop from 65 micrograms per cubic meter to 35. If an area, such as Salt Lake County, has a certain number of days that exceed that standard in any three-year stretch, then that area comes under special federal scrutiny and must take extra steps to cut pollution.
Salt Lake, Davis, Utah and Weber counties have barely kept under those limits in the few years since the first-generation PM 2.5 standard went into effect. In Logan, a small basin that has seen some of the nation's worst PM 2.5 episodes in the past few years, local officials are braced for a period of sooty air to trigger an EPA clampdown.
Frank O'Donnell of the Washington, D.C.-based Clean Air Watch, said a growing body of scientific evidence shows the health damage from air pollution is serious and widespread. Nine groups sued the agency in 2003 to force the EPA to adopt PM 2.5 curbs focused on public health.
"In this case, real science has been distorted by political science," O'Donnell said.
Dan Riedinger, a spokesman for the utility trade group, the Edison Electric Institute, said stricter regulations ''may yield limited, if any, tangible benefit to public health'' because soot pollution is not as great a threat as it was eight years ago.
In contrast, he said the costs to industry ''can hurt local businesses, drive away new ones, and inflict severe penalties on areas unable to quickly reach compliance.''
Even though the new PM 2.5 regulation is likely to be just as contentious as the first one, some Utahns have already begun to wonder what can be done to cut PM 2.5 further.
"We'll have a period of years to see how we will achieve these standards," Heying said, noting that regulators will need to work with industry to find additional pollution reductions. "All the low-hanging fruit has already been harvested. We're all going to have to figure out the best way to meet the new standard."
Heying said one complicating factor in the West is pollution from forest fires. The state has been at odds with the EPA for several years over smoke pollution and pollution from fireworks. Federal regulators insist these episodes count for the PM 2.5 averages, despite the state's protests.
Kathy VanDame of the Utah Clean Air Coalition knocked the EPA for opting against the standard recommended by its advisers, which would have lowered the annual limit to about 14 micrograms a year and the 24-hour standard to about 30 micrograms per cubic meter. And she agreed that Utah is likely to struggle to meet the new limits.
"There is not going to be a silver bullet," she said. "It is going to take a lot of little things."
The Associated Press contributed to this story.