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NARSTO Workshop on Innovative Methods for Emission Inventory Development and Evaluation University of Texas, Austin October 14-17, 2003 |
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Evaluation Of On-road Vehicle Emissions Inventory
Eric M. Fujita1 and Till Stoeckenius2
1 Division of Atmospheric Sciences, Desert Research Institute, Reno, NV 89512-1095
2 ENVIRON International Corp., Novato, CA 94945
This paper provides an overview of methods for evaluating on-road emissions inventories. The methods are described in a guidance document that describes the technical basis, assumptions, limitations, and data requirements for each method and recommends a step-wise application of the methods. The initial steps utilize readily available data to reconcile the spatial and temporal patterns (including long-term trends) in ambient pollutant concentrations and ratios and volatile organic compound (VOC) speciation profiles with corresponding data derived from emission estimates. Additional “top-down” evaluations that may be considered in the second level involve fuel-based inventory, source apportionment by receptor modeling, and performance evaluations of air quality simulation models. This guidance document is intended to allow state and local air pollution agencies to assess the uncertainties associated with on-road emission inventories and to identify areas for improvement. Results of the applications of these evaluation methods in California´s South Coast Air Basin over the past fifteen years will be reviewed as a case study.