Changes in engine technologies and after-treatment devices can profoundly alter the chemical composition of the emitted pollutants. To investigate these effects, we characterized the emitted particles' chemical composition of three diesel and four gasoline Euro 5 light-duty vehicles tested at a chassis dynamometer facility. The dominant emitted species was black carbon (BC) with emission factors (EFs) varying from 0.2 to 7.1 mg km⁻¹ for direct-injection gasoline (GDI) vehicles, from 0.02 to 0.14 mg km⁻¹ for port fuel injection (PFI) vehicles, and 0.003 to 0.9 mg km⁻¹ for diesel vehicles. The organic matter (OM) EFs varied from 5 to 103 µg km⁻¹ for GDI gasoline vehicles, from 1 to 8 µg km⁻¹ for PFI vehicles, and between 0.15 and 65 µg km⁻¹ for the diesel vehicles. The first minutes of cold-start cycles contributed the largest PM fraction including BC, OM, and polycyclic aromatic hydrocarbons (PAHs). Using a high-resolution time-of-flight mass spectrometer (HR-ToF-AMS), we identified more than 40 PAHs in both diesel and gasoline exhaust particles including methylated, nitro, oxygenated, and amino PAHs. Particle-bound PAHs were 4 times higher for GDI than for PFI vehicles. For two of the three diesel vehicles the PAH emissions were below the detection limit, but for one, which presented an after-treatment device failure, the average PAHs EF was 2.04 µg km⁻¹, similar to the GDI vehicle's values. During the passive regeneration of the catalysed diesel particulate filter (CDPF) vehicle, we measured particles of diameter around 15 nm mainly composed of ammonium bisulfate. Transmission electron microscopy (TEM) images revealed the presence of ubiquitous metal inclusions in soot particles emitted by the diesel vehicle equipped with a fuel-borne-catalyst diesel particulate filter (FBC-DPF). X-ray photoelectron spectroscopy (XPS) analysis of the particles emitted by the PFI vehicle showed the presence of metallic elements and a disordered soot surface with defects that could have consequences on both chemical reactivity and particle toxicity. Our findings show that different after-treatment technologies have an important effect on the emitted particles' levels and their chemical composition. In addition, this work highlights the importance of particle filter devices' condition and performance.

The characterization of vehicle exhaust emissions of volatile organic compounds (VOCs) is essential to estimate their impact on the formation of secondary organic aerosol (SOA) and, more generally, 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 motorway (MW) cycles. Positive matrix factorization (PMF) analysis is carried out for the first time on proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS) datasets of vehicular emission. 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 combustion regimes. Merged PTR-ToF-MS and automated thermal desorption gas chromatography mass spectrometer (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. In general, emissions during the CU cycle exceed those during the MW cycle. The gasoline direct injection (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 vehicle (15 and 3 mg/km). For all vehicles, emissions are dominated by unburnt fuel and incomplete combustion 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 of monoaromatics (68%) and alkanes (15%). Intermediate volatility organic compounds (IVOCs) range from 2.7 to 13% of the emissions, comprising essentially linear alkanes for the diesel vehicle, while naphthalene accounts up to 42% of the IVOC fraction for the gasoline vehicles. This work demonstrates that PMF analysis of PTR-ToF-MS datasets and GC-MS analysis of vehicular emissions provide a revised and deep characterization of vehicular emissions to enrich current emission inventories.

Cigarette smoke is a complex mixture of chemical compounds which are emitted during the processes of tobacco combustion. Electronic cigarettes (e-cigs) are expected to produce less harmful compounds due to the absence of tobacco leaf combustion. However, potential risks of the passive exposure to the aerosol exhaled by e-cig users have been raised in the last decade. In this study, the aerosols with diameter less than 1 μm (PM₁) produced by vaping of various e-cig liquids were compared to those generated by smoking conventional cigarettes in real time. The mass and number concentration along with the number size distribution were measured in a closed room of 35 m³ volume. Our results showed that aerosols emitted from e-cig liquids had a different profile compared to those from conventional cigarettes. Although e-cigs initially produced higher particle mass and number concentrations, their emissions had much shorter lifetime of approximately 10–20 s, in comparison with the conventional and hand-rolling cigarette particulate emissions which had a dissipation time of approximately 1.4 h in a 35 m³ room. E-cigs emitted aerosols which volatilized rapidly, as they probably consisted almost only of propylene glycol and/or vegetable glycerin.