National leaders in the field joined USU faculty at an air-quality symposium at the Logan campus. They addressed the bowl-shaped topography that makes northern Utah and southern Idaho particularly susceptible to inversions in the winter months.

Just nine months ago, Cache Valley residents from Wellsville to Preston, Idaho, experienced more than 40 days of 500-foot thick haze on the valley floor.

Kent Pinkerton, professor at the Institute of Toxicology and Environmental Health at the University of California at Davis, said short-term exposure to concentrated levels of air pollution, along with low-level exposure for longer periods of time, create chronic illness in human beings.

Arden Pope, professor of economics at BYU, said the physical damage from pollution goes beyond the airways and lungs, and can trigger strokes and heart attacks.

Children, who take 60 percent more breaths than adults, are particularly susceptible to chemicals in the air.

Randy Martin, professor of environmental engineering at USU, presented the results of extensive research in Cache Valley and said his colleagues are laying wagers on what day in the coming winter that air-pollution levels in the valley exceed EPA standards, which would trigger federal intervention. It's not a matter of if it happens, Martin said. He's got his money on Jan. 8.

While cars and cows are the largest contributors of harmful emissions to the air, wood burning stoves, forest trees and even soils add to the particulate levels, according to Anthony Wexler, professor of engineering and land, water and air resources at UC Davis.

Frank Mitloehner, an air-quality extension specialist at UC Davis, said two areas “ripe for picking” to control pollution are the cows and cars.

Farmers could reduce harmful ammonium nitrate emissions by changing what they feed the animals during the winter months. He also suggested implementing mandatory emissions testing for vehicles to “get the dirty cars off the road.”

USU research indicates that 4 percent of automobiles tested cause 25 percent of the air pollution. Martin's research also shows that all of the population centers in Cache Valley have the same concentrations of particulates during an inversion.

“It's everybody's problem,” he said.

abrunson@sltrib.com