The sources of benzo[a]pyrene in diesel exhaust emissions

Results are presented for the combustion of diesel fuel spiked with [7,10-14C]benzo[a]pyrene in a Perkins Prima DI diesel engine. Diesel exhaust samples were collected using the Total Exhaust Solvent Scrubbing Apparatus (TESSA) sampling system. Analysis of the exhaust samples was performed by radio-high performance liquid chromatographic techniques developed for this research. The major radioactive species in the exhaust was identified as [14C]benzo[a]pyrene which had survived combustion. The survival was 0.04% of the original activity. The initial specific activity of the radiochemical in the fuel (248 μCi/mg) was similar to that in the exhaust (200 μCi/mg). It was concluded that benzo[a]pyrene in the fuel surviving combustion was the major source of benzo[a]pyrene in the exhaust. Contributions from other sources including lubricating oil and pyrosynthetic formation within the combustion chamber amounted to no more than 20%.