On-road measurement of NH3 emissions from gasoline and diesel passenger cars during real world driving conditions

NH3is a precursor of PM2.5which deteriorates urban air quality, affects human health and impacts theglobal radiation budget. Since vehicles are important sources of NH3in urban areas, we have satisfac-torily studied the possibility of measuring NH3emissions from gasoline and SCR-equipped diesel light-duty vehicles during real driving on-road operation using a portable FTIR. The performance of theportable FTIR resulted to be comparable to that of a laboratory-based FTIR during a series of experimentsperformed in the Vehicle Emission Laboratory (VELA) using the World-harmonized Light-duty Test Cycle(WLTC). Higher on-road NH3emission factors were obtained for the gasoline vehicle than for the diesel.High NOx emissions were measured from the diesel vehicle, indicating a low efficiency of the DeNOxsystem, SCR. On-road NH3emission factors were ~2 times lower than during the laboratory tests at 23 Cfor both vehiclesNH3emissions were not observed for the diesel vehicle during cold start operation.However, NH3cold start emissions from the gasoline vehicle were up to 2 orders of magnitude higherthan during the entire road trips, ranging from 45 to 134 mg km 1. Cold start emissions are of paramountimportance as they commonly take place in urban areas. Hence, future urban reductions in PM2.5mightneed to take into consideration the introduction of NH3emissions limits for passenger cars
Real driving emissions, Portable measurement, Ammonia, Particulate precursor, Cold start emissions