Tunnel measurements of the PAH, carbon thermogram and elemental source signature for vehicular exhaust

Abstract To obtain a vehicular signature suitable for source apportionment of carbonaceous aerosols, submicron particulate emissions were sampled from inside the air duct of a 1.1 km freeway tunnel. Samples were analyzed for polyaromatic hydrocarbons, elemental composition and mass. The carbon and nitrogen components were characterized by thermal analysis. Measured elemental loadings (plus values for oxygen and hydrogen scaled to the sulfur nitrogen and carbon) are within 15% of the gravimetrically determined mass. Black carbon and volatile carbon, as distinguished by the thermograms, account for 30–38% and 22–29% of the fine particle mass respectively. Variations in the traffic pattern between midday and evening rush hour were used to distinguish diesel and gasoline vehicles.