This document examines how air monitoring is used in Ontario to assess local air quality issues. It conducted interviews with Ministry of Environment staff, municipalities, public health units, and others involved in air monitoring. It finds interest in using air monitoring to inform land use and transportation planning by validating models, measuring background levels, and assessing specific locations. However, air monitoring is seen as an expensive tool best used complementarily with modelling. There is no consensus around responsibility for comprehensive local airshed assessments. The document recommends the Ministry of Environment provide support and resources to public health units and municipalities for priority air monitoring studies to inform decision-making.