Results from the first assessment of air quality over the Canadian oil sands-one of the largest industrial undertakings in human history-using satellite remote sensing observations of two pollutants, nitrogen dioxide (NO₂) and sulfur dioxide (SO₂), are presented. High-resolution maps were created that revealed distinct enhancements in both species over an area (roughly 30 km × 50 km) of intensive surface mining at scales of a few kilometers. The magnitude of these enhancements, quantified in terms of total mass, are comparable to the largest seen in Canada from individual sources. The rate of increase in NO₂between 2005 and 2010 was assessed at 10.4 ± 3.5%/year and resulted from increases both in local values as well as the spatial extent of the enhancement. This is broadly consistent with both surface-measurement trends and increases in annual bitumen production. An increase in SO₂ was also found, but given larger uncertainties, it is not statistically significant. NO2 and SO2 show distinct enhancements over surface mining sites in the oil sandNO2 and SO2 enhancement cover 30x50km2; NO2 increasing at a rate of 11%/yearDemonstrates method for analyzing localized sources using coarse resolution data