title: Repeat Fuel Specific Emission Measurements on Two California Heavy-Duty Truck Fleets.
abstract: The University of Denver repeated its 2013 fuel specific gaseous and particle emission measurements on two California heavy-duty vehicle fleets. In 2015 1456 measurements at the Port of Los Angeles and 694 measurements at the Cottonwood weigh station in northern California were collected. The Port fleet changed little since 2013, increasing the average age (+1.8 years), accompanied by an increase in particle mass (PM) by +266% (0.03 ± 0.01 to 0.11 ± 0.01 gPM/kg of fuel) and black carbon (BC) by +300% (0.02 ± 0.003 to 0.08 ± 0.01 gBC/kg of fuel). Particle number (PN) also increased (1.5 × 1014± 2.5 × 1013to 2.8 × 1014± 2.8 × 1013PN/kg of fuel) by a smaller percentage (+87%). Chassis model year 2008 and 2009 vehicles currently dominate the fleet, accounting for the majority of these increases. The long-haul Cottonwood fleet decreased in fleet age (-0.6 model years), where half the decreases in fuel specific PM (-66%), BC (-65%), and PN (-19%) emissions are due to the newer fleet; an increased fraction of pre-2008 chassis model year vehicles with retrofit diesel particulate filters (DPFs) account for the remaining reductions. These opposing emissions trends emphasize the importance of fully functional DPFs.
authors.affiliation: Department of Chemistry and Biochemistry, University of Denver , Denver, Colorado 80208, United States.
authors.forename: Molly J
authors.identifier: 0000-0003-2394-7603
authors.initials: MJ
authors.lastname: Haugen
authors.affiliation: Department of Chemistry and Biochemistry, University of Denver , Denver, Colorado 80208, United States.
authors.forename: Gary A
authors.identifier: 0000-0003-0136-997X
authors.initials: GA
authors.lastname: Bishop
mesh_terms: D000393:Air Pollutants; D002140:California; D004784:Environmental Monitoring; D018986:Motor Vehicles; D053260:Soot; D001335:Vehicle Emissions
chemical_list: D000393:Air Pollutants; D053260:Soot; D001335:Vehicle Emissions