Complying with Tighter PM10 Air Quality Standards Amid the Dust In the Pacific Northwest.

Windblown dust affects air quality within the Columbia Plateau of the US Pacific Northwest. While the US Environmental Protection Agency (EPA) is considering revising the National Ambient Air Quality Standard for PM10 (particulate matter ≤10 µm in diameter), the implication of adopting a new level and form of the PM10 Standard on compliance with the Standard is unknown in the region. Daily observations of PM10 were made at Kennewick and Spokane, WA from 2000 through 2010. Compliance with the PM10 Standard was determined for both the current (not to exceed 150 µg m-3 on more than one day) and recommended (not to exceed 65 or 85 µg m-3 based upon the 98th percentile) Standards. Spokane, but not Kennewick, complies with the current PM10 Standard. Under the recommended PM10 Standards, both Kennewick and Spokane would violate the Standard at the 65 µg m-3 level. The results of this study suggest that communities within the Columbia Plateau will not comply with the recommended PM10 Standard at a level of 65 µg m-3. The Exceptional Event Rule and research on management practices to windblown dust will continue to be important strategies for achieving compliance with PM10 Air Quality Standards in the region.