Implications of changing PM10 Air Quality Standards on Pacific Northwest communities affected by windblown dust

The US Environmental Protection Agency (EPA) is currently reviewing the National Ambient Air Quality Standards (NAAQS) for Particulate Matter. EPA is considering the recommendation to change both the form and level of the PM10 (particulate matter ≤10 μm in diameter) Standard. The implication of the recommended NAAQS for PM10 on air quality is explored in this study. Daily observations of PM10 were made at Kennewick and Spokane, WA from 2000 through 2010. The number of violations of the PM10 Standard was determined for both the current (not to exceed 150 μg m−3 on more than one day per year) and recommended (not to exceed 65 or 85 μg m−3 based upon the 98th percentile) Standards. The current PM10 Standard has only been violated at Kennewick. Under the recommended PM10 Standards, Kennewick would have violated the Standard at both the 65 and 85 μg m−3 levels while Spokane would have violated the Standard at only the 65 μg m−3 level. The results of this study suggest that the recommended NAAQS for PM10 using a level of 85 μg m−3 will tend to result in fewer violations of the Standard and using a level of 65 μg m−3 will tend to result in more violations of the Standard in the Inland Pacific Northwest. The Exceptional Event Rule and research on management practices to control the emission of fugitive dust will continue to be important strategies for achieving compliance with PM10 Air Quality Standards in the Inland Pacific Northwest.