Oxygenated volatile organic compounds (VOCs) as significant but varied contributors to VOC emissions from vehicles

Abstract. Vehicular emissions are an important source for volatile organic compounds (VOCs) in urban and downwind regions. In this study, we conducted a chassis dynamometer study to investigate VOC from vehicles using gasoline, diesel, liquefied petroleum gas (LPG) as fuel. Time-resolved chemically characterized by proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) with high frequency. Our results show that emission factors of VOCs generally decrease the improvement standards gasoline vehicles, whereas variations diesel more diverse. Mass spectrum analysis PTR-ToF-MS suggests cold starts significantly influence while influences less vehicles. Large differences between observed most species being higher than especially oxygenated (OVOCs) heavier aromatics. These indicate quantification may be characterization vehicular exhausts. suggest pairs (e.g., C14 aromatics / toluene ratio) could potentially provide good indicators distinguishing The fractions OVOCs total determined combining measurements hydrocarbons canisters online observations PTR-ToF-MS. We contribute 9.4 % ± 5.6 (52 %–71 %), highlighting importance detecting these OVOC emissions. demonstrated large number measured