Land & Environment

Toward Fewer Bad Air Days

Utah State University chemist Phil Silva recently received a National Science Foundation Small Grant for Exploratory Research to delve more deeply into the chemical reactions responsible for Cache Valley’s winter pollution.

“The grant funds one year of support for unconventional projects that require quick data,” says Silva, assistant professor in the Department of Chemistry and Biochemistry.
The unique landscape of Cache Valley, home of Utah State, contributes to the area’s wintertime air woes. During cold months, the mountain-encircled valley experiences periods of pollution caused by “inversions” or altitudinal increases in temperature. Stagnant high pressure systems trap cold air – along with unhealthy concentrations of pollutants – beneath warm air in the bowl-shaped dale.
The main sources of polluted air come out of the tailpipes of cars and cows.
“Ammonium nitrate accounts for about 50 to 70 percent of northern Utah’s air pollution,” says Silva. “Ammonia is a byproduct of livestock waste. During inversions, our snow-covered valley allows ammonia to accumulate, which reacts with vehicle exhaust to form tiny ammonium nitrate particles.”
A rapidly expanding metropolitan area, Cache Valley has more than 85,000 registered vehicles and provides a busy travel corridor for freight and tourist traffic between the southwestern U.S. and Rocky Mountain recreational areas. The area’s robust dairy and meat industries boast upwards of 75,000 head of cattle, 13,000 hogs and 4,000 sheep.
With colleagues at the University of California at Riverside, Silva will study how organic compounds in agricultural emissions interact with nitrogen oxide emissions from vehicles.
“We hope to generate data on the rates of these reactions,” he says. “Our results should provide information that will assist county and state officials in coming up with plans about how to address pollution levels.”
In recent winters, Cache Valley has racked up unhealthy readings for PM2.5; that is, particles less than 1/40 the diameter of a human hair. Such readings are worrisome because the minute particles settle deep in the lungs and can cause health problems, says Silva, who serves as an advisor to the Bear River Health Department and the State of Utah’s Division of Air Quality.
Understanding the chemistry behind the pollution, he says, is the first step in formulating solutions. “Once we understand the causes, we can implement policies and provide information to the public so that everyone can do their part to lower pollution.”
Related links:
Contact: Phil Silva [], 435-797-8192

Writer: Mary-Ann Muffoletto [], 435-797-1429

Phil Silva

USU chemist Phil Silva received NSF funding to study northern Utah's winter air pollution mix.


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