Equation B-6  ( HAP Emissions – GSE ) can be used to calculate the  HAP emissions from an  individual piece (or type) of equipment. T he THC to TOG conversion factor s (as used in  EDMS/AEDT) for diesel, gasoline, CNG, and LPG equipment are 1.07, 1.043, 1.002, 1.0995, respectively.  On-site ground access vehicles are the various fleets of public and privately -owned motor  vehicles traveling on airport roadways, and in parking lots and parking garages by passengers,  employees, commercial vehicles and cargo carriers. These fleets typically  include cars, vans,  taxis, shuttles, buses and trucks. Ground access vehicles emissions vary by vehicle and fuel type  (gasoline or diesel), travel distance, operating speed, and ambient temperature.  Outside airport property, these ground access vehicles operate on the local and regional roadway  networks while traveling to and from an airport and are difficult to distinguish from background  (i.e., non-airport) traffic.  The EPA has identified 21 HAPs that are designated as Mobile Source Air  Toxics (MSATs) to  signify those HAPs that are emitted by motor vehicles. $^{58 }$MOVES is currently the best tool for  estimating these motor vehicle emissions of MSATs. 59  The MOVES output is expressed in units of grams/vehicle -mile and can be segregated by  vehicle and fuel type (e.g., light duty gas oline, heavy duty diesel, etc.) or combined into a  composite value representative of the entire Ground access vehicle fleet.  B.2.4.1 Methodology  B.2.4  Ground Access Vehicles  Equation B-6. HAP Emissions - GSE  I = L x M/100 x B x D x F x H x 1/60 x 1/1000  APPENDIX B$_{ }$ Where:  I = Mass of THC of interest, expressed in kilograms (kg)  L = Average rated brake horsepower  M = Load factor, expressed as a percentage  B = Time in operation, expressed as minutes  D = THC emissions index, expressed in grams per horsepower-hour (g/hp-hr)  F = THC to TOG conversion factor (unitless)  H= Speciation profile for HAP of interest (mass fraction)  1/60 = Conversion factor from minutes to hours  1/1000 = Conversion factor from grams to kilograms  58  EPA,  Mobile Source Air Toxics ,  http://www.epa.gov/otaq/toxics.htm.  59  Information regarding MOVES, including software and user’s guide can be found at the following websites:  http://www.epa.gov/otaq/models/moves/index.htm#generalinfo.  58$_{ }$