We conducted four source apportionment simulations using the Community Multiscale Air Quality (CMAQ) photochemical grid modelling system in order to investigate and assess the relative importance of specific emissions sources and/or geographic regions on ambient ozone and PM air quality in the Alberta Oil Sands Region (AOSR). Local point and area sources, medium range transport of mobile sources and biogenic emissions were examined.The elimination of emissions from local stationary point sources reduced 8-h ozone concentrations and greatly reduces the PM2.5 concentrations in AOSR; similar results are seen in the local area source zero-out simulations but with less ozone and PM2.5 reductions than seen in the local point source zero-out run. Although the mobile source medium-range transport reduced 8-h ozone concentrations in the urban plume from Edmonton that results in some ozone and PM2.5 concentration reductions in the southern part of the AOSR, it has little effect on the elevated ozone and PM2.5 concentrations in the oil sands development area of the AOSR where the highest ozone and PM2.5 concentrations are estimated. The elimination of all anthropogenic emissions in Alberta so that only biogenic emissions remained resulted in large reductions in 8-h ozone concentrations in the AOSR, with the highest remaining ozone in the 50–52 ppb range occurring south of Fort McMurray; very low PM2.5 concentrations are also estimated across Alberta, including the AOSR, when anthropogenic emissions are eliminated in Alberta.

Emission sources sensitivity study for ground-level ozone and PM2.5 due to oil sands development using air quality modelling system: Part II – Source apportionment modelling (PDF Download Available).