Does California’s EMFAC2017 Vehicle Emissions Model Under-predict California Light-duty Gasoline Vehicle NOx Emissions?

Authors

Gary A. Bishop, University of DenverFollow

Publication Date

2021

Document Type

Article

Organizational Units

Chemistry and Biochemistry

Keywords

Atmospheric chemistry, Emissions, Pollutants, EMFAC

Abstract

On-road remote sensing measurements of light and medium-duty gasoline vehicles collected within California’s South Coast Air Basin since 1999 generally fall within the range of observed summer ambient molar NO_x/CO measurements collected during morning rush hours. Compared with ambient and on-road emissions, the California Air Resources Board EMFAC model under predicts 2018 gasoline vehicle NO_x emission factors by more than a factor of 2.6. Contributing to these differences is that vehicles older than model year 2006 have NO_x emission deterioration rates that are up to 4 time’s higher on-road than predicted by the EMFAC model. A fuel-based inventory using the 2018 on-road gasoline emission factors for CO and NO_x results in total CO emissions similar to the basin inventory but NO_x emissions that are 74% higher than the inventory. The higher NO_x emission estimates from on-road gasoline vehicle measurements makes their contribution to the inventory slightly larger than heavy-duty diesel vehicles. We have found LEV I (1994 - 2003) gasoline vehicles are a major source of these on-road emissions and that significant NO_x reductions in the South Coast Air Basin are being overlooked by not targeting the high emitters for removal.

Copyright Statement / License for Reuse

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

Rights Holder

Gary A. Bishop

Provenance

Received from author

File Format

application/pdf

Language

English (eng)

Extent

35 pgs

File Size

424 KB

Publication Statement

This is an Accepted Manuscript for the article

Bishop, G. A. (2021), Does California’s EMFAC2017 Vehicle Emissions Model Under-predict California Light-duty Gasoline Vehicle NOx Emissions?, J. Air & Waste Manage. Assoc., 71:5, 597-606. DOI: 10.1080/10962247.2020.1869121

Copyright is held by the Air and Waste Management Association

Recommended Citation

Bishop, G. A. (2021), Does California’s EMFAC2017 Vehicle Emissions Model Under-predict California Light-duty Gasoline Vehicle NOx Emissions?, J. Air & Waste Manage. Assoc., 71:5, 597-606. DOI: 10.1080/10962247.2020.1869121

DOI Link

https://doi.org/10.1080/10962247.2020.1869121