title: Windblown dust contributes to high PM2.5concentrations.
abstract: The revised National Ambient Air Quality Standards for PM include fine particulate standards based upon mass measurements of PM2.5. It is possible in arid and semi-arid regions to observe significant coarse mode intrusion in the PM2.5 measurement. In this work, continuous PM10, PM2.5, and PM1.0 were measured during several windblown dust events in Spokane, WA. PM2.5 constituted approximately 30% of the PM10 during the dust event days, compared with approximately 48% on the non-dusty days preceding the dust events. Both PM10 and PM2.5 were enhanced during the dust events. However, PM1.0 was not enhanced during dust storms that originated within the state of Washington. During a dust storm that originated in Asia and impacted Spokane, PM1.0 was also enhanced, although the Asian dust reached Washington during a period of stagnation and poor dispersion, so that local sources were also contributing to high particulate levels. The "intermodal" region of PM, defined as particles ranging in aerodynamic size from 1.0 to 2.5 microns, was found to represent a significant fraction of PM2.5 (approximately 51%) during windblown dust events, compared with 28% during the non-dusty days before the dust events.
authors.affiliation: Department of Civil & Environmental Engineering, Washington State University, Pullman, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Claiborn
authors.forename: D
authors.initials: D
authors.lastname: Finn
authors.forename: T V
authors.initials: TV
authors.lastname: Larson
authors.forename: J Q
authors.initials: JQ
authors.lastname: Koenig
mesh_terms: D000397:Air Pollution / Q000032:analysis*; D003889:Desert Climate; D004391:Dust; D004784:Environmental Monitoring / Q000592:standards; D008962:Models, Theoretical; D010316:Particle Size; D015203:Reproducibility of Results
chemical_list: D004391:Dust