Emission of mutagenic, irritating and odorous substances from gasoline fueled vehicles with different emission control systems

The objective of this study was to evaluate the effect of different engine modifications and emission control systems. Both regulated and unregulated emissions were characterized. Unregulated emissions of special interest were mutagenic and carcinogenic compounds as well as odorous and irritating substances. Three consecutive test runs were performed using 8 cars during two different driving cycles. The results support the understanding that reduction of the regulated emissions CO, HC, and NO x, as well as PAH and other organic compounds, may be gained from modification of the engine in combination with a thermal reactor or an oxidation catalyst. However, the same reduction is not necessarily obtained regarding the emission of particles and mutagenic substances. No good indicator of mutagenic activity was found in this study except PAH. It is recommended that measurement of unregulated emissions should be included in studies regarding engine development work. A car equipped with a three-way catalyst was on a low emission level in most cases.