The Government of Alberta is reporting to Albertans on the results of a technical investigation of air trigger exceedances for Nitrogen Dioxide (NO2) and Sulphur Dioxide (SO2) at air monitoring stations in the Lower Athabasca Region (LAR) for the year 2012. The investigation was initiated under the Lower Athabasca Region Air Quality Management Framework for Nitrogen Dioxide (NO2) and Sulphur Dioxide (SO2) (LAR AQMF) and helps fulfill a commitment made in the Lower Athabasca Regional Plan to initiate a management response when annual assessments indicate triggers or limits have been exceeded. The monitoring results are found in the 2012 Status of Ambient Environmental Conditions report. The air quality investigation followed the first two steps (verification and preliminary assessment) in the management response and recommendations from the investigation will inform the selection of mitigative management actions. This report presents the findings of the investigation, as described below. The goal of the investigation was to understand the factors that affected ambient levels of SO2 and NO2 at the stations that were at Level 2 or Level 3 under the LAR AQMF in 2012 and to understand possible future changes. Sources of NO2 and SO2 in the LAR from several emissions inventories were reviewed. Relationships between these emission sources and elevated levels of SO2 and NO2 were investigated through the analysis of 2012 ambient NO2 and SO2 data at the Level 2 and Level 3 stations. In order to assess past and future changes in the region, a historical trend analysis and predictions from three modelling studies were also reviewed.