While efforts are under way to deal with nitrate pollution in groundwater in the Lower Yakima Valley, concern is now being raised about airborne nitrates that contribute to poor air quality, which, in turn, can impact human health.
Elevated levels of nitrates in Yakima air samples are substantially higher than elsewhere in the state, which has prompted the state Department of Ecology and other stakeholders to launch a study to try to find out why and suggest possible solutions.
Nitrates form in the atmosphere through chemical processes involving the presence of “precursor compounds,” including nitrogen oxide, ammonia and volatile organic compounds. Sources of these precursor compounds are numerous.
As much as 30 percent of the air pollution in Yakima can come from nitrates. Elsewhere in the state — Tacoma, Seattle and Vancouver, for example — nitrates make up as little as 5 percent, Ecology officials said, citing results from speciation monitors that pinpoint amounts of individual pollutants.
Jeff Johnston, manager of science and engineering in Ecology’s Air Quality Program, said the purpose of the study is to try to find the sources of Yakima’s higher levels of aerosol nitrates.
“We don’t know enough at this point. Certainly, there are a lot of agriculture emissions in the Upper Valley and Lower Valley. It might be related to that,” he said. “Where we have speciation monitors, there’s not the concentration of agricultural activity as there is in Yakima. It’s too early to speculate on that.”
A majority of the overall pollution in Yakima’s air comes from wood smoke, vehicle exhaust and dust.