title: Characterization of PM25and PM10in the South Coast Air Basin of Southern California: Part 2-Temporal Variations.
abstract: The South Coast Air Quality Management District (SCAQMD) conducted a 1-year special particulate monitoring study from January 1995 to February 1996. This monitoring data indicates that high PM10and PM2 5concentrations were observed in the fall (October, November, and December), with November concentrations being the highest. During the rest of the year, PM2.5and PM10masses gradually increased from January to September. Monthly PM10mass varied from 20 to 120 |ig/m3, and monthly PM25mass varied from 13 to 63 |j.g/m3. The PM2.5-to-PM10ratio varied daily and ranged between 22 and 96%. Two types of high-PM days were observed. The first type was observed under fall stagnation conditions, which lead to high secondary species concentrations. The second type was observed under high wind conditions, which lead to high primary coarse particles of crustal components. The highest 24-hr average PM10concentration (226.3 |ig/m3) was observed at the Fontana station, while the highest PM25concentration (129.3 |ig/m3) was observed at the Diamond Bar station.
authors.affiliation: a South Coast Air Quality Management District, Planning and Policy , Diamond Bar , California , USA.
authors.forename: Bong Mann
authors.initials: BM
authors.lastname: Kim
authors.affiliation: a South Coast Air Quality Management District, Planning and Policy , Diamond Bar , California , USA.
authors.forename: Solomon
authors.initials: S
authors.lastname: Teffera
authors.affiliation: a South Coast Air Quality Management District, Planning and Policy , Diamond Bar , California , USA.
authors.forename: Melvin D
authors.initials: MD
authors.lastname: Zeldin