Development of a Microscale Emission Factor Model for Particulate Matter (MicroFacPM) for Predicting Real-Time Motor Vehicle Emissions

摘要

The United States Environmental Protection Agency's National Exposure Research Laboratory has initiated a project to improve the methodology for modeling human exposure to motor vehicle emissions. The overall project goal is to develop improved methods for modeling the source through the air pathway to human exposure in significant microenvironments of exposure. The PART models (used in the United States, except California) and EMFAC models (used in California only) used to estimate emissions are suitable only for regional (county) scale modeling and emission inventories because of their dependence on aggregated vehicle-miles-traveled data. These emission models are not designed to estimate real-time emissions needed for human exposure studies near roadways. Therefore, there is a need to develop site-specific realtime emission factor models for PM emissions. A microscale emission factor model for predicting site-specific real-time motor vehicle particulate matter (MicroFacPM) emissions for TSP, PM_(10) and PM_(2.5) has been developed. It uses site-specific available information on the vehicle fleet composition. The algorithm used to calculate emission factors in MicroFacPM is disaggregated based on the site-specific vehicle fleet. The emission factors are calculated from a real-time fleet, rather than from a fleet-wide average estimated by a vehicle-miles-traveled weighting of the emission factors for different vehicle classes. MicroFacPM requires input information necessary to characterize the site-specific real-time fleet being modeled. Other variables required are average vehicle speed, time and day of the year, ambient temperature and relative humidity.