Emissions of currently non-regulated gaseous pollutants from modern passenger cars

The current vehicle type approval regulation in Europe controls specific exhaust gas constituents, while additional species may prove harmful for the environment and human health. This paper presents emission results of currently non-regulated gaseous pollutants from passenger cars. To this aim, four cars of different powertrain and exhaust aftertreatment technologies have been tested in a wide range of conditions. Ammonia (NH3), nitrous oxide (N2O) and methane (CH4) were included in the measurements, together with the currently regulated gaseous pollutants. The results showed that NH3 forms in the three-way catalyst (TWC) in harsh accelerations, while CH4 is the main hydrocarbon emitted by natural gas and diesel vehicles, the latter equipped with lean NOx trap. In spark-ignition engines, N2O formation was observed during the warm-up period of the TWC.