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Nicole Boliaux, Deseret News archives
Lt. j.g. J.C. Clark, co-pilot, does his preflight checks on a Twin Otter DHC-6 before takeoff at the Salt Lake City International Airport in Salt Lake City on Sunday, Feb. 12, 2017. The National Oceanic and Atmospheric Administration has been flying over Salt Lake, Cache and Utah valleys to survey chemical conditions responsible for the formation of particulate pollution, known as PM2.5.

SALT LAKE CITY — A first of its kind study that probed the layers of northern Utah's inversions two years ago is unraveling additional layers of information on what pollutants to target.

Specifically, the findings published in Geophysical Research Letters back a slew of rules passed by the Utah Air Quality Board that tamped down emissions of volatile organic compounds in everything from hair spray to paints and solvents.

"This is an issue we have been aware of for some time," said Bryce Bird, director of the Utah Division of Air Quality. "Understanding more about air pollution is an important aspect of what we do. That is why we are focused on the research."

Researchers from the University of Colorado at Boulder, the National Oceanic and Atmospheric Administration and the University of Utah unexpectedly discovered that reducing emissions of nitrogen oxides from burning fossil fuels could actually — at least initially — increase ammonium nitrate pollution.

Jeffrey D. Allred, Deseret News
The sun rises over the smog-filled Salt Lake Valley on Monday, Jan. 14, 2019.

A major component of the Salt Lake area pollution is ammonium nitrate aerosol, which forms from emissions of nitrogen oxides, volatile organic compounds and ammonia, according to researchers.

"No one has looked at air pollution in winter before this way. Our findings could hold true in other areas with severe winter aerosol pollution, including mountain valleys across the U.S. West and urban areas in East Asia and Europe," said Caroline Womack, lead author of the study and a scientist working in the NOAA Earth System Research Laboratory.

John Lin, co-author of the study and a professor of atmospheric sciences at the University of Utah, said the insight arose from some of the most extensive measurements of chemistry involved in the Wasatch Front's wintertime pollution problem.

In February 2017, a Twin Otter airplane carrying research scientists and 2,000 pounds of instrumentation conducted a series of flights charting the anatomy of Utah's wintertime inversions.

The $2 million Utah Winter Fine Particulate Study was the first of its kind in the country to use aircraft and state-of-the-art instruments to study the conditions at play that lead to PM2.5 formation.

Nicole Boliaux, Deseret News archives
Lt. Robert Mitchell, air commander, and Lt. j.g. J.C. Clark, co-pilot are seen in the cockpit of a Twin Otter DHC-6 at the Salt Lake City International Airport in Salt Lake City on Sunday, Feb. 12, 2017. The National Oceanic and Atmospheric Administration (NOAA) has been flying over Salt Lake, Cache and Utah valleys to survey chemical conditions responsible for the formation of particulate pollution, known as PM2.5.
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Researchers gathered pollution data from multiple ground sites from Cache County to Utah County and used the airplane to probe the different layers of the inversion with missed approaches at regional airports dipping down to 15 feet above ground.

Typically, pollution mitigation efforts aimed at reducing high levels of ammonium nitrate aerosol are focused first on shaving nitrogen oxides by reducing the burning of fossil fuels, researchers say.

But Bird said the division has long incorporated a faceted approach going after both nitrogen oxides and volatile organic compounds.

"It is not ignoring one for the other," he said, adding the division is evaluating the results of the study, which was published earlier this month.