Ambient fine particulate matter (PM2.5) in Canadian oil sands communities: Levels, sources and potential human health risk.

An investigation of levels and potential sources affecting ambient fine particulate matter (PM2.5) and associated risk to public health was undertaken at two Canadian oil sands communities (Fort McKay and Fort McMurray) using a 4-year dataset (2010-2013). Geometric mean concentrations of PM2.5 at Fort McKay and Fort McMurray are not considered high and were 5.47μg/m3 (interquartile range, IQR=3.02-8.55μg/m3) and 4.96μg/m3 (IQR=3.20-7.04μg/m3), respectively. Carcinogenic risks of trace elements were below acceptable (1×10-6) and/or within tolerable risk (1×10-4), and non-carcinogenic risks were below a safe level of concern (hazard index=1). Positive matrix factorization (PMF) modeling revealed five sources, where fugitive dust appeared as the major contributor to PM2.5 mass (Fort McKay: 32%, Fort McMurray: 46%) followed by secondary sulfate (31%, 42%) and secondary nitrate/biomass burning (26%, 8%). Other minor sources included a mining/mobile and a Mn-rich/Mn-Co-Zn-rich source. Source-specific risk values were also estimated and were well below acceptable and safe level of risks. Further work would be needed to better understand the contribution of secondary organic aerosols to PM2.5 formation in these oil sands communities.