Influence of biomass burning on wintertime fine particulate matter: Source contribution at a valley site in rural British Columbia

Particulate matter (PM) speciation data were collected between November 2004 and August 2006 in the rural valley area of British Columbia, Canada. Source apportionment of PM was performed using a receptor model, positive matrix factorization (PMF), to identify possible sources of PM and determine the influence of each identified source on local air quality. High concentrations of PM2.5 (<2.5 μm) were observed in winter months with an average of 18 μg m−3, while the average concentration in summer months was approximately 6 μg m−3. PMF apportioned the PM2.5 mass into seven factors identified as Na-rich, secondary sulfate, wood burning, wood processing, crustal material, traffic, and winter heating. The most important sources affecting ambient air quality in the deep valley rural area were wood burning and winter heating factors. In winter the wood burning and winter heating sources accounted for approximately 31% and 43% of the total PM2.5 mass, respectively, indicating the significant influence of biomass burning in the rural area. The wood burning and winter heating factors were highly associated with high organic carbon and volatile organic compounds. The identity of the sources was further elucidated by exploring their relationship with other measured parameters; a correlation study was conducted to evaluate relationships between the sources, gaseous pollutants, and meteorological variables.