Oil sand extraction operations are responsible for the production of large amounts of specific air pollutants known as secondary organic aerosols (SOAs) observed during airborne measurements in Canada, finds a study published in Nature this week.

Oil production from oil sands is the cause of numerous environmental concerns, but the contribution of oil sand exploration to SOAs - a component of atmospheric particulate matter formed from the chemical transformation of atmospheric organic compounds, which are known to affect air quality and climate - has remained unclear.

John Liggio and colleagues combined aircraft measurements taken over Canada, laboratory experiments and a modelling study to provide a quantitative assessment of the contribution of oil sand emissions to SOAs. They find that evaporation and atmospheric oxidation of organic vapours emitted from the mined oil sands are directly responsible for the formation of the majority of SOAs recorded in the airborne measurements, resulting in an SOA production rate of 45-84 tonnes per day.

These findings suggest that oil sands are one of the largest sources of anthropogenic SOAs in North America. The authors propose that these atmospheric effects should be taken into account when assessing the global environmental impacts of current and planned bitumen and heavy oil extraction projects.