Comparison of two winter air quality episodes during the California Regional Particulate Air Quality Study.

The duration, strength, spatial extent, and chemical makeup of particulate matter (PM) are compared for two winter air quality episodes captured during the California Regional Particulate Air Quality Study (CRPAQS). Each episode, from the beginning of the buildup through dissolution, lasted about 3 weeks. The first episode occurred from December 14, 1999, through January 1, 2000, with peak 24-hr average fine particulate matter (PM2.