Enhanced Deposition, Polycyclic Aromatic Compounds (Active), Oil Sands Region

Environment Canada has been monitoring ambient air in the oil sands region for polycyclic aromatic compounds (PACs) since December 2010. Ambient air samples collected using the established protocols and schedule of the National Air Pollution Surveillance (NAPS) program are termed active PAC samples. Active sampling is done at three sites (Mannix [AMS5], Lower Camp [AMS11] and Fort McKay South [AMS13], Alberta). Ambient air concentrations in the oil sands region can be used to evaluate regional differences in PAC concentrations and can be compared with levels of PACs measured in other parts of Canada and to ambient air quality objectives. Average PAC levels across the three sites in the oil sands region are comparable to urban/sub-urban levels across Canada and are elevated compared with background rural sites in Canada. Higher concentrations of PACs are measured at sites that are closer to oil sands mining and upgrading facilities compared with sites that are further away. Benzo(a)pyrene (BaP) is a PAC formed mainly as a result of incomplete combustion of carbon-based materials and fuels during industrial and other human activities, as well as natural events such as forest fires. It is associated with heavy molecular weight PACs that may be more carcinogenic. The data from the measurements conducted so far (data exclude May and June 2011 due to forest fires) indicate that BaP levels exceed the Alberta ambient air quality objective of 0.3 ng/m3 as an annual average concentration (based on chronic and carcinogenic human health effects) at one location. The PAC air concentrations will be used to determine the amount of dry deposition, which cannot be measured directly. This information can be integrated with information on other pollutants, and their deposition, to determine cumulative effects on ecosystems and communities in and downwind of the oil sands region.