Nitrate air pollution is higher in the Yakima Valley than many other places in Washington. The state Department of Ecology noticed the pocket of unusually high amounts of nitrate air pollution and commissioned researchers at Washington State University and Central Washington University to determine its source.
These fine particulates are so tiny that you can't see them, but if you breathe them in at high concentrations, they can cause heart and respiratory problems.
Jeff Johnston, with the Washington Department of Ecology, said three things are needed to create the nitrate pollution: ammonia from agriculture; car exhaust; and cold, humid temperatures.
"It’s formed in the air, so it's going to be harder to control. It's more complicated to control than other sources," Johnston said.
Other sources include wood-burning stoves, the source of most air pollution in Central Washington.
Johnston says fine particulate pollution in the Yakima Valley comes in just under Environmental Protection Agency air quality standards.
Tim VanReken, who helped write the study for Washington State University, says air pollution in the Yakima Valley sometimes can reach unhealthy levels. That usually happens on cold, still winter nights, where inversions don't allow the pollution to disperse.
For their study, researchers used an instrument trailer. They parked the trailer at Yakima Valley Community College for three weeks in January of 2013. They collected extra data out of Toppenish, Wash., during the same time.
The researchers did a similar study in Boise three years ago and found similar results. VanReken says they were able to collect more data for the Yakima study.
"The weather cooperated as well," VanReken says. "We were able to see events in ways that helped us understand the problem better. There's always an element of chance, if you only have a few weeks to go look at a certain situation."
Next, researchers will look at computer models to figure out how to reduce the nitrate air pollution.