When routine air testing showed that higher-than-usual nitrate levels were detected in the Yakima area, we commissioned research by Washington State University (WSU) and Central Washington University (CWU) to find out what was causing the elevated levels.
About 25 percent of Yakima’s wintertime particle pollution (PM2.5) is made up of nitrate in the air. These nitrate levels were higher than anywhere else in the state. Researchers at WSU and CWU monitored Yakima’s air quality over three weeks in January 2013 to better understand the high nitrate levels. The most likely cause of high nitrate levels was determined to be the interaction of:
- Ammonia from agricultural activities.
- Oxides of nitrogen from vehicles.
- The right weather conditions.
The solution to reduce nitrate particles in Yakima has not yet been determined and requires a detailed air quality modeling study.
In December 2009, EPA classified the Tacoma-Pierce County area as a nonattainment area (not meeting an air quality standard) because fine particle (PM2.5) pollution levels did not meet healthy limits from 2006 – 2008. We were required to develop an air quality plan called a State Implementation Plan (SIP) showing what actions would be taken to control air pollution in the area. Wood smoke was found to contribute more than half of the PM2.5 measured during the winter. Fine particles from wood smoke and industry have declined each year since 2006.
In December 2010, EPA revised the monitoring requirements for measuring lead in the air. The amendments required eight states to conduct one-year monitoring studies at airports with lead emissions between 0.50 and 1.0 tons per year. EPA identified two airports in Washington that met the study criteria: Auburn Municipal and Harvey Field.