Time-resolved characterization of primary particle emissions and secondary particle formation from a modern gasoline passenger car
- 1Aerosol Physics Laboratory, Department of Physics, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland
- 2Atmospheric Composition Research, Finnish Meteorological Institute, P.O. Box 503, 00101, Helsinki, Finland
- 3VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, 02044 VTT, Espoo, Finland
- 4Centre for Environmental and Climate research, Lund University, Box 118, 22100 Lund, Sweden
- 5Division of Nuclear Physics, Lund University, Box 118, 22100 Lund, Sweden
- 6Department of Meteorology, Pennsylvania State University, University Park, PA, USA
Abstract. Changes in vehicle emission reduction technologies significantly affect traffic-related emissions in urban areas. In many densely populated areas the amount of traffic is increasing, keeping the emission level high or even increasing. To understand the health effects of traffic-related emissions, both primary (direct) particulate emission and secondary particle formation (from gaseous precursors in the exhaust emissions) need to be characterized. In this study, we used a comprehensive set of measurements to characterize both primary and secondary particulate emissions of a Euro 5 level gasoline passenger car. Our aerosol particle study covers the whole process chain in emission formation, from the tailpipe to the atmosphere, and also takes into account differences in driving patterns. We observed that, in mass terms, the amount of secondary particles was 13 times higher than the amount of primary particles. The formation, composition, number and mass of secondary particles was significantly affected by driving patterns and engine conditions. The highest gaseous and particulate emissions were observed at the beginning of the test cycle when the performance of the engine and the catalyst was below optimal. The key parameter for secondary particle formation was the amount of gaseous hydrocarbons in primary emissions; however, also the primary particle population had an influence.