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DEVELOPMENT OF A MICROSCALE EMISSION FACTOR MODEL FOR PARTICULATE MATTER (MICROFACPM) FOR PREDICTING REAL TIME MOTOR VEHICLE EMISSIONS

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http://cfpub.epa.gov/si/si_public_comments.cfm

Citation:

Singh, R. B., A H. Huber, AND J N. Braddock. DEVELOPMENT OF A MICROSCALE EMISSION FACTOR MODEL FOR PARTICULATE MATTER (MICROFACPM) FOR PREDICTING REAL TIME MOTOR VEHICLE EMISSIONS. Presented at PM 2000 AWMA Conference, Charleston, SC, January 24-28, 2000.

Impact/Purpose:

The research is planned to meet the following objectives:

Support is provided to HEASD Tasks by Alan Huber. (60% 9524 New Air Toxics Modeling, ; 10% 5732 PM Population Exposure Modeling; 10% 3948 Next Generation MMMP Exposure Modeling; 10% N533 PM Toxic agent exposure modeling, and 10% 3957 Integrated Human Exposure Source-to-Dose Modeling)

  • Development of data and algorithms for exposure modeling in urban areas, to be used in refined probabilistic exposure models being developed elsewhere, to allow prediction of human exposures for an urban population.

  • Characterize exposures and variability of concentrations in critical microenvironments in urban areas using targeted measurement studies and refined air quality models.

  • Identify critical human activities influencing exposures, especially identifying microenvironments that are key to exposures to urban air toxics.

  • Develop methods (measurements, dispersion modeling, receptor modeling) to distinguish exposures to "near field" sources - like indoor sources, human activities or hobbies, or nearby point or area sources - from "background" concentrations or from distant sources that can be modeled well by compartmental or air quality models.

  • Provide data and algorithms based on a scientific understanding of exposure dynamics for inclusion in NERL human exposure models and other models like OAR's TRIM..

    • Description:

    Health risk evaluation needs precise measurement and modeling of human exposures in microenvironments to support review of current air quality standards. The particulate matter emissions from motor vehicles are a major component of human exposures in urban microenvironments. Current human exposure models using simplified assumptions based on fixed air monitoring stations and regional scale emission models do not represent the actual human exposures and should be improved. A number of independent studies have found that present mobi8le sources particulate emission factor models are not reliable at estimating microscale human exposures in-vehicles and near roadways. The particulate emission factor model PART5 (used in USA except California) and EMFAC (used in California only) calculate the composite emission factors for each vehicle class by weighting the emission factors calculated for each model year by the travel fraction for that model year and then summing the weighted factors. This method is suitable for regional scale emission estimates and for emission invntory, but not for emission factor estimates in microenvironments needed for human exposure models.

    In view of the above, a micro-scale emission factor model (MicroFacPM) for predicting real-time automobile PM 10 and PM 2.5 emissions is being developed, using the same database that was used to develop part 5. The algorithm used to calculate emission factors
    In MicroFacPM is disaggregated. It calculates emission factors in real-time form the on-road vehicle fleet. MicroFacPM fully accounts for exhaust and non-exhaust (such as tire wear, break wear and re-entrained road dust) sources and can also be used near roadway intersections. The model can be applied to estimate emission factors for fleet of vehicles between January 1, 1990, and December 31, 2010, and therefore allows a comparison of current emissions with past and future, or in a contribution of particulate matter from different sources. Microfacpm will be an important tool to characterize the relationship between fixed site monitors and actual human exposures in different microenvironments near roadways. The model is also appropriate for comparative analyses; for example, comparing the potential impact of one traffic control measure versus another.

    Record Details:

    Record Type:DOCUMENT( PRESENTATION/ ABSTRACT)
    Product Published Date:01/25/2000
    Record Last Revised:06/21/2006
    Record ID: 62612