Polynuclear Aromatic Hydrocarbons in Vehicle Exhaust Gas

Evidence is presented to determine the relationship between fuel composition and polynuclear aromatic hydrocarbons (PNA) formation.

Emission rates of PNA were determined for gasoline engines in simulated city driving; in order to confirm the results, experiments were carried out with a vertical flow reactor. The PNA emission was found to depend on the different aromatic hydrocarbons present in the fuel. The addition of tetraethyl lead (TEL) to gasoline had little effect on PNA emission.

The carcinogenic hydrocarbons like 1.2 benzanthracene and benz(a)pyrene, particularly associated with the more carbonaceous part of the soot, are preferentially deposited on the combustion chamber walls, as pointed out from vertical reactor experiments.