The Air Quality Transport Corridor Separation overlay applies to identified strategic traffic routes in urban Auckland. The width of the overlay varies depending on the volume of traffic carried by particular roads, or particular stretches of road. The purpose of the overlay is to manage the adverse air quality effects of vehicle emissions on land use activities involving people with particular sensitivities to these emissions. Young children are identified as a group with high sensitivity to the adverse effects of vehicle emissions in terms of their health and overall well-being. The principle activities addressed in this overlay are those associated with childcare facilities.