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Air Emissions Inventories

Volume 4 - Mobile Sources

This document provides technical documentation of mobile source activity data collection as a part of the ten volumes of the Emissions Inventory Improvement Program (EIIP) materials. These volumes provide standard procedures for calculating air emissions data with targeted quality objectives using cost effective approaches, but in some cases have become outdated. 

“Volume 4 – Mobile Sources” provides a reference for collection of activity data needed as input to onroad and nonroad mobile models. For onroad mobile sources, the chapters include guidance on developing vehicle registration distributions, mileage accumulation, rates from inspection and maintenance programs, development of fleet characteristics, fuel consumption, and vehicle miles travelled. For nonroad mobile sources, the chapters include approaches for estimating lawn and garden equipment activity.

The mobile source emissions sections in this volume have been replaced by onroad and nonroad mobile model documentation available from the Office of Transportation and Air Quality

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