Detailed Speciation of Non-Methane Volatile Organic Compounds in Exhaust Emissions from Diesel and Gasoline Euro 5 Vehicles Using Online and Offline Measurements

International audienceThe characterization of vehicle exhaust emissions of volatile organic compounds (VOCs) isessential to estimate their impact on the formation of secondary organic aerosol (SOA) and, moregenerally, air quality. This paper revises and updates non-methane volatile organic compounds(NMVOCs) tailpipe emissions of three Euro 5 vehicles during Artemis cold urban (CU) and mo-torway (MW) cycles. Positive matrix factorization (PMF) analysis is carried out for the first timeon proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS) datasets of vehicularemission. Statistical analysis helped to associate the emitted VOCs to specific driving conditions,such as the start of the vehicles, the activation of the catalysts, or to specific engine combustionregimes. Merged PTR-ToF-MS and automated thermal desorption gas chromatography mass spec-trometer (ATD-GC-MS) datasets provided an exhaustive description of the NMVOC emission factors(EFs) of the vehicles, thus helping to identify and quantify up to 147 individual compounds. Ingeneral, emissions during the CU cycle exceed those during the MW cycle. The gasoline directinjection (GDI) vehicle exhibits the highest EF during both CU and MW cycles (252 and 15 mg/km),followed by the port-fuel injection (PFI) vehicle (24 and 0.4 mg/km), and finally the diesel vehi-cle (15 and 3 mg/km). For all vehicles, emissions are dominated by unburnt fuel and incompletecombustion products. Diesel emissions are mostly represented by oxygenated compounds (65%)and aliphatic hydrocarbons (23%) up to C22, while GDI and PFI exhaust emissions are composed ofmonoaromatics (68%) and alkanes (15%). Intermediate volatility organic compounds (IVOCs) rangefrom 2.7 to 13% of the emissions, comprising essentially linear alkanes for the diesel vehicle, whilenaphthalene accounts up to 42% of the IVOC fraction for the gasoline vehicles. This work demon-strates that PMF analysis of PTR-ToF-MS datasets and GC-MS analysis of vehicular emissions providea revised and deep characterization of vehicular emissions to enrich current emission inventories