Naphthalene is the simplest and most abundant polycyclic aromatic hydrocarbon (PAH) in California fuels, with concentrations of up to 2,600 mg L
in gasoline and 1,600 mg L
in diesel fuel. In this work, naphthalene emission factors for gasoline and diesel vehicles are combined with an activity-based automobile inventory to characterise anthropogenic naphthalene emissions in the South Coast Air Basin of California (SoCAB). A three-dimensional air quality model is used to examine transport and chemical reaction losses of naphthalene in the SoCAB. Inclusion of naphthalene emissions from on-road gasoline and diesel vehicles was found to increase modelled SOA growth by up to 10%. Hence, reductions of naphthalene from both gasoline and diesel fuels may be an effective means of reducing the emissions of an important SOA-forming precursor to the atmosphere of large urban centres with characteristics similar to the SoCAB. The implications of these findings are discussed.
Keywords: air quality modelling, environmental pollution, naphthalene, photochemistry, secondary organic aerosol, SOA, gasoline and diesel emissions factors