Scientist studying chemistry of Cache Valley’s winter inversions

Unlike most who conduct air quality studies, a scientist at USU is studying the actual chemistry of pollutants in the air and how they react with each other to create the severe inversions Cache Valley experiences during the winter.

After evaluating conditions in the area, Philip Silva said there is more to poor air quality than a vehicle’s emissions – 60 to 70 percent of pollution is composed of ammonium nitrate, a chemical that is the result of a mix of agricultural and industrial emissions.

“The majority pollutant buildup during the winter is ammonium nitrate,” Silva said. “It is really bad.”

Ammonia is released from agricultural sources including urine, fertilizer, feed lots and other particles found in concentrated livestock facilities, Silva said.

The majority of nitrate emissions come from burning fossil fuels.

When the two chemicals are airborne, they combine and create ammonium nitrate.

“The fundamental chemical is no different than what we all learned back in elementary school,” Silva said.

Ammonium nitrate is a type of pollutant to which most of the state is vulnerable because of agricultural activity and rapid urbanization, he said.

The other fraction of pollution comes from organic carbon. Those sources include diesel, fireplace smoke and, in the summer, barbeque grilling. Even though they make up a smaller percentage of pollution, their effects can be just as serious, Silva said.

“While ammonium nitrate makes up 60 to 70 percent, the other 30 to 40 percent is obviously significant as well,” Silva said.

He said organic carbon is something that hasn’t really been reported on before, so he is continuing to research that kind of emission. He believes there are chemical reactions here that have not previously been seriously studied.

Even after studying conditions in the valley for four years, Silva said there are still questions that need answers.

“There is no silver bullet for the type of problem we have. We have a mix of urban and rural pollution. There is no easy way to fix the problem,” he said. “Basically, at a general level, we know what happens but, in detail, there are still a lot of questions.”

While he knows what the majority of pollutants are and where they come from, Silva said he is still studying the subset reactions of emissions. He is also researching environmental conditions that are unique to this area.

However, he said it is important to remember that studies and efforts made here could have an effect on the future of the world.

Silva serves on boards for the State of Utah’s Division of Air Quality and the Bear River Health Department. Silva said the data he is collecting will be used to create a long-term plan to decrease pollutants in the air and the occurrence of inversions.

For now, Silva said people can focus on vehicle emission control to help lower the severity of inversions.

Silva also said studying chemicals in the air will help the area get a better idea of what needs to be done to live in compliance with regulations set by the EPA. With stricter rules in place, the valley is often in direct violation of the guidelines. The EPA has predicted northern Utah will be experiencing these same conditions until at least 2020.

Silva said he is hoping the data he has collected will be used proactively and people will be cautious.

With the help of colleagues and students, Silva said he is conducting other related studies.

“This is an ongoing process with lots of questions remaining to be answered,” he said. “There are lots of different aspects we don’t have answers to.”

-ariek@cc.usu.edu