Comparison of vehicle emissions by EMFAC-HK model and tunnel measurement in Hong Kong

Xiaoliang Wang (Corresponding Author), Lung-Wen Antony Chen, Kin-Fai Ho, Chi Sing Chan, Zhuozhi Zhang, Shuncheng Lee, Judith C. Chow, John G. Watson

Research output: Journal article publicationJournal articleAcademic researchpeer-review

4 Citations (Scopus)


On-road vehicular emissions were measured in a Hong Kong roadway tunnel and compared to those from a mobile emission model (EMFAC-HK) for the 2003 and 2015 fleets to assess emission changes and effectiveness of emission controls. EMFAC-HK results compared well with tunnel measurement for the 2015 fleet with differences ≤50% for most pollutants. Both measurement and modeled estimates show that non-methane hydrocarbon (NMHC) and PM2.5 decreased by over 40% from 2003 to 2015. Tunnel measurements also show that nitrogen dioxide (NO2) and liquefied petroleum gas (LPG) -related NMHC emissions increased due to expanded installation of diesel oxidation catalysts and LPG fueling. Motorcycles and LPG-fueled public light buses (3.7% of the fleet) contributed disproportionally high fractions of carbon monoxide (CO; 27%) and NMHC (49%) and deserve additional emission controls. Fuel economy improvements did not result in expected carbon dioxide (CO2) emission reductions, indicating that more aggressive CO2 reductions, particularly from heavy-duty vehicles, are needed.
Original languageEnglish
Article number118452
JournalAtmospheric Environment
Publication statusPublished - 1 Jul 2021


  • Air pollution
  • Emission factors
  • Emission model
  • Tunnel study
  • Vehicle emissions

ASJC Scopus subject areas

  • Environmental Science(all)
  • Atmospheric Science


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