Analysis of Benzene Emissions from Vehicles and Vehicle Refueling

In recent years, several investigators have characterized and measured hydrocarbon components, including benzene, in vehicle exhaust. This paper presents an analysis of benzene exhaust emission data reported from approximately 100 light-duty vehicles. Results indicate that on average, benzene exhaust emissions from catalyst-equipped vehicles are significantly less than those from non-catalyst vehicles. In addition, benzene exhaust emissions from 3-way catalyst vehicles appear to be significantly less than those from oxidation catalyst vehicles, on average. These observations parallel analogous average reductions in total hydrocarbons, indicating that modern catalyst-based exhaust emission controls reduce benzene emissions to approximately the same degree as they reduce total hydrocarbons. Also, benzene evaporative emissions from 3-way catalyst vehicles appear to be substantially less than those from oxidation catalyst vehicles. Finally, a benzene refueling emission rate was calculated. Its contribution to total benzene emissions appears to be very small.