$^{2}$Importantly, the information provided in this figure is not meant to be definitive or all-inclusive in terms of dictating the type(s) of  air quality assessments that are required for FAA projects or actions . Rather, the information is provided as a guide in determining  which analyses are the most appropriate.  Aviation Emissions and Air Quality Handbook  26$_{ }$ Runway Rehabilitation  Obstruction Removal  Air Traffic Control Tower  Action Type  Increase in Aircraft Operations  Change in Runway Utilization  Change in Fleet Mix  Increase in Taxi Time/Delay  Increase in Motor Vehicle Trips  Air Traffic Procedures < 3,000 ft  Air Traffic Procedures > 3,000 ft  Land Acquisition  Navigational System  $^{1}$The symbols indicate the relative level of appropriateness of an analysis to a project/action:  = High,  = Medium,  = Low 