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EMFAC 2007 (v2.3) Emission Factors

Table A9-5 of the 1993 Handbook provides a methodology for calculating on-road mobile source emissions using EMFAC output files based on the year of interest, typical average speeds, etc.  When using this methodology, the most current version of EMFAC should be used – DO NOT USE TABLES A9-5-J-1 THROUGH A9-5-J-10 OR TABLES A9-5-K-1 THROUGH A9-5-K-10.  This methodology requires relatively detailed information about a project to be able to calculate on-road mobile source emissions.  To simplify calculating on-road mobile source emissions, the SCAQMD has derived mobile source emission factors using CARB’s EMFAC 2007 (v2.3) BURDEN model.  The emission factors are derived by dividing the total daily district-wide emissions by total daily vehicle miles traveled to obtain emission factors in pounds per mile traveled.  To assist the CEQA practitioner, two sets of emission factors have been developed as described below.  Please note, the on-road emission factors below include CO2 and CH4 emission factors.

The following emission factors have been derived by taking the weighted average of vehicle types and simplifying them into two categories – passenger/light-duty and medium-/heavy-duty vehicles (e.g., delivery trucks).  These emission factors should be used for typical land use projects where passenger/light-duty vehicles generate the majority of the vehicle trips.

Heavy-Heavy-Duty Vehicles


The following emission factors have been derived specifically for the heavy-heavy-duty truck (HHDT) vehicle category.  HHDTs have a vehicle weight ranging between 33,001 to 60,000 pounds.  These emission factors should be used to calculate on-road mobile source emissions for projects where HHDTs comprise a relatively large percentage of the total vehicle trips from a project (approximately 10 percent of more).  These emission factors should be used for projects that generate a large number of HHDT trips per day, such as warehouse/distribution facilities, landfills, etc.  Since these types of projects may also include passenger/light-duty vehicles, the emission factors above should be used to calculate mobile source emissions for the passenger/light-duty vehicles in conjunction with the following emission factors to calculate total on-road mobile source emissions for a project.  The following HHDT factors (or the appropriate EMFAC 2007 emission factors) should also be used when performing a mobile source toxics analysis (see below).

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