An “event-based” approach
to characterize complex
air pollutant mixtures was applied in the Oil Sands region of northern
Alberta, Canada. This approach was developed to better-inform source
characterization and attribution of the air pollution in the Indigenous
community of Fort McKay, within the context of the lived experience
of residents. Principal component analysis was used to identify the
characteristics of primary pollutant mixtures, which were related
to hydrocarbon emissions, fossil fuel combustion, dust, and oxidized
and reduced sulfur compounds. Concentration distributions of indicator
compounds were used to isolate sustained air pollution “events”.
Diesel-powered vehicles operating in the mines were found to be an
important source during NOx events. Industry-specific volatile
organic compound (VOC) profiles were used in a chemical mass balance
model for source apportionment, which revealed that nearby oil sands
operations contribute to 86% of the total mass of nine VOC species
(2-methylpentane, hexane, heptane, octane, benzene, toluene, m,p-xylene, o-xylene,
and ethylbenzene) during VOC events. Analyses of the frequency distribution
of air pollution events indicate that Fort McKay is regularly impacted
by multiple mixtures simultaneously, underscoring the limitations
of an exceedance-based approach relying on a small number of air quality
standards as the only tool to assess risk.