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## A5.2.2.2 Emission Factors 

The uncontrolled emission factors for Equation A5-3 ( Total Pollutant Emissions for Generators - EPA’s AP-42 Method ) for gasoline and diesel engines are given in Chapter 3.3, Gasoline and Diesel Industrial Engines 22 , of EPA’s AP-42. These emission factors can be used for engines that have a rated power of up to 250 horsepower (hp) for gasoline engines and up to 600 hp for diesel engines. Diesel engines greater than 600 hp are covered in Chapter 3.4, Large Stationary Diesel and All Stationary Dual-fuel Engines 23 , of EPA’s AP-42. 

The uncontrolled emission factors for Equation A5-4 ( Total Pollutant Emissions for Generators – U.S. Air Force’s Method ) for generators powered by reciprocating engines are given in Table A5-1 ( Uncontrolled Emission Factors for Generators ). These emission factors are also default values used in EDMS/AEDT. Note that for SO$_{2}$, the percent of sulfur in the fuel must be obtained to calculate the emission factor. The type of fuel and sulfur content should be available from the fuel supplier and/or the airport operator. 

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Source : Emissions and Dispersion Modeling System (EDMS) User’s Manual, FAA-AEE-07-01 (Rev. 10 – 06/07/13), June 2013, http://www.faa.gov/about/office_org/headquarters_offices/apl/research/models/edms_model/media/EDMS_5.1.4_User_Manual.p df; and Jagielski, Kurt D., and Robert J. O'Brien, Calculation Methods for Criteria Air Pollutant Emission Inventories , July 1994. 

Notes: 

$^{1 }$Emission factors are expressed in pounds per thousand gallons for fuel and pounds per million cubic feet for natural gas. $^{2 }$(S) signifies the fuel sulfur content, expressed as weight percent sulfur, which is multiplied by the coefficient given to obtain the emission factor for SO$_{2}$. 

## A5.2.3 Snowmelters 

Snowmelters at airports are used to remove snow from airfield surfaces. They are portable and stationary sources that are typically powered by gasoline or diesel -fuel or natural gas. Emissions are dependent on type of fuel and the amount of fuel being burned over the time period be ing analyzed. 

