vehicles transporting airport and tenant employees; and vehicles transporting cargo to and from  the airport.  Air emissions associated with these vehicles  are a function of traffic volumes and speeds,  distances traveled, vehicle operating characteristics, fuel type, and ambient conditions.  Computational methods and modeling techniques for assessing ground access vehicles emissions  are discussed in  Section 6  ( Preparing an Emissions Inventory ) and  Section 7  ( Conducting  Dispersion Modeling ). For detailed instruction and guidance on how to compute  ground access  vehicles emissions refer to  Appendix A4  ( Ground Access Vehicle Emission Inventory for  Criteria Pollutants ).  Stationary and area sources of air emissions at airports consist of both fuel combustion and non- combustion sources. Typical sources include boilers, heaters, generators, snowmelters,  incinerators, live-fire training facilities, aircraft engine testing, fuel storage tanks, cooling towers,  coating and painting operations, de -icing and anti -icing operations, solvent degreasers and  sand/salt piles.  Air emissions associated with fuel combustion are a function of equipment type, equipment size,  fuel type, combustion processes and air emission control measures.  Non-combustion sources  typically emit evaporative emissions (e.g., fuel storage tanks) and/or  fugitive dust emissions  (e.g., sand and salt piles).  Assessment methods and modeling tools for calculating stationary/area source emissions discussed in  Section 6  ( Preparing an Emissions Inventory ) and  Section 7  ( Conducting  Dispersion Modeling ). For detailed instruction and guidance on how to compute stationary/area  emissions refer to  Appendix A5  ( Stationary Sources Emission Inventory for Criteria Pollutants ).  Construction activities are temporary and variable depending on location, duration,  and level of  activity and are generally confined to  a construction site and access/egress roadways.  These  emissions occur predominantly  from the operation of heavy construction equipment ( e.g.,  backhoes, bulldozers), on- and off-road vehicles used for the transport and delivery of supplies  and material (e.g., cement trucks, dump trucks), and on- road vehicles used by construction  workers getting to and from  a construction site (e.g., cars, pick- up trucks). Construction  emissions also include fugitive dust produced from construction materials staging, demolition ,  and earthwork activities, as well as evaporative emissions from asphalt paving operations.  Assessment methods and models for calculating construction-related emissions are discussed in  Section 6.1.2  ( Airport Construction Emissions).  For detailed instruction and guidance on how to  compute construction-related emissions refer to  Appendix A6  ( Construction Emission Inventory  for Criteria Pollutants ).  Other sources of air emissions associated with aviation, in general, and airports, in particular that  are of emerging interest because of their connection to GHG emissions include the following:  3.1.7.  Other Sources  12$_{ }$ 3.1.6.  Construction  3.1.5.  Stationary and Area Sources  Aviation Emissions and Air Quality Handbook 