Abstract
The Biscuit fire burned close to 2,000 km super(2) of forested land in southwestern Oregon in July and August, 2002. August, 2002 also was a time in which PM sub(2.5) concentrations were higher than typical in California Central Valley cities located several hundred kilometers to the southeast. The concentrations of two monosaccharide anhydrides, levoglucosan and mannosan, were measured in aerosol samples collected at four California Air Resource Board sites in Central Valley cities for the purpose of determining how the wildfire smoke affected air quality. Levoglucosan concentrations ranged from the detection limit of 18 ng m super(-3) to about 400 ng m super(-3). While days with high levoglucosan concentrations generally had above average to high PM sub(2.5) concentrations, there were also days with high PM sub(2.5) concentrations with low levoglucosan concentrations. Although mannosan was only detected in a small number of samples, the levoglucosan to mannosan ratios in these samples were consistent with smoke from softwood combustion. A wildfire source levoglucosan to PM sub(2.5) concentration ratio was used to estimate the PM sub(2.5) concentration originating from smoke. From this method, smoke was found to be a significant (greater than 10% of the total PM sub(2.5) concentration) on occassions. The estimated smoke PM sub(2.5) concentration always remained less than 10 [mu]g m super(-3) and contributed to less than a third of the total PM sub(2.5) concentration. Because the PM sub(2.5) concentrations were higher than typical August values, either there were other factors leading to high PM sub(2.5) concentrations in August 2002, or the smoke estimation method underestimated the smoke concentration.