Effects of Reformulated Gasoline and Motor Vehicle Fleet Turnover on Emissions and Ambient Concentrations of Benzene

Gasoline-powered motor vehicles are a major source of toxic air contaminants such as benzene. Emissions from light-duty vehicles were measured in a San Francisco area highway tunnel during summers 1991, 1994-1997, 1999, 2001, and 2004. Benzene emission rates decreased over this time period, with a large (54 ± 5%) decrease observed between 1995 and 1996 when California phase 2 reformulated gasoline (RFG) was introduced. We attribute this one-year change in benzene mainly to RFG effects: 36% from lower aromatics in gasoline that led to a lower benzene mass fraction in vehicle emissions, 14% due to RFG effects on total nonmethane organic compound mass emissions, and the remaining 4% due to fleet turnover. Fleet turnover effects accumulate over longer time periods: between 1995 and 2004, fleet turnover led to a 32% reduction in the benzene emission rate. A ~4 g m-3 decrease in benzene concentrations was observed at a network of ambient air sampling sites in the San Francisco Bay area between the late 1980s and 2004. The largest decrease in annual average ambient benzene concentrations (1.5 ± 0.7 g m-3 or 42 ± 19%) was observed between 1995 and 1996. The reduction in ambient benzene between spring/summer months of 1995 and 1996 due to phase 2 RFG was larger (60 ± 20%). Effects of fuel changes on benzene during fall/winter months are difficult to quantify because some wintertime fuel changes had already occurred prior to 1995. (A)

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/0013936X
• Authors:
  • HARLEY, R A
  • HOOPER, D S
  • KEAN, A J
  • KIRCHSTETTER, T W
• Publication Date: 2007-2

Language

• English

Media Info

• Pagination: 5084-5088
• Serial:
  • Environmental Science & Technology
  • Volume: 49
  • Issue Number: 16
  • Publisher: American Chemical Society
  • ISSN: 0013-936X
  • EISSN: 1520-5851
  • Serial URL: http://pubs.acs.org/journal/esthag

Subject/Index Terms

• TRT Terms: Age; Air pollution; Aromatic hydrocarbons; Automobiles; Benzene; Pollutants; Surveillance; Tunnels; Vehicle fleets
• Geographic Terms: United States
• ITRD Terms: 1757: Age; 2452: Air pollution; 7358: Aromatic compounds; 1243: Car; 2442: Emission; 1223: Fleet of vehicles; 9101: Surveillance; 3374: Tunnel; 8122: USA
• Subject Areas: Bridges and other structures; Energy; Environment; Vehicles and Equipment; I15: Environment; I90: Vehicles;

Filing Info

• Accession Number: 01043421
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD
• Created Date: Mar 6 2007 9:06AM