CE22 - Mobilité et systèmes urbains durables

New POLlutant EMIssions from modern Euro 6 CarS: atmospheric transformations and implications for urban air quality and health – POLEMICS

New POLlutant EMIssions from modern Euro 6 CarS: atmospheric transformations and implications for urban air quality and health

The demand for urban mobility is steadily increasing and the growing number of vehicles in cities poses major environmental and health issues. POLEMICS addresses urgent questions on new Euro6 car emissions. The consortium composed by analytical mass spectrometry experts, toxicologists and air quality modellers will investigate the nature, the fate and the impacts on air quality and health (toxicity and genotoxicity) of Euro 6 emissions combining in laboratory and real world measurements.

Impacts of new aftertreatment devices on car emissions and emission transformations in urban environments

The major scientific objectives addressed within POLEMICS are synthetized below: <br />1. to characterize and quantify novel or poorly characterized gaseous compounds are emitted by Euro 6 light-duty vehicles (as reduced nitrogen compounds, oxygenated compounds, intermediate-volatility OCs compounds)<br />2. to characterize and quantify particulate matter in the PM1 range (below 1µm emitted by Euro 6 light-duty vehicles (metals nanoparticles, chemical composition and organic fraction speciation of PAHs including functionalized PAHs)<br />3. to generate a comprehensive database of emitted compounds and deliver the associated emission factors <br />4. To compare emissions at the dynamometer test bench and during real-world driving-based measurements<br />5. To Investigate the atmospheric fate of Euro6 compounds emitted by Euro 6 light-duty vehicles (formation of secondary pollutants)<br />6. To Investigate toxicity and gentotoxicity of the emitted particles and of those formed upon photo-oxidation<br />7. To assess the impact of a fleet change to Euro 6 vehicles on the air quality of a major<br />metropolitan area (Paris)<br />Via its novel and cross-disciplinary approach POLEMICS will provide an integrated and independent<br />assessment of direct (exhaust emissions) or indirect (secondary formed aerosol) traffic contribution to urban air quality and related health impacts.

POLEMICS could take advantage of state-of-the art instrumentation for the analysis of Euro6 light duty vehicles and at the same time we could use the new chassis dynamometer at IFSTTAR (now EASE). Emissions studies of regulated pollutants were analysed with traditional methods (HORIBA) while a series of high performing instruments based on mass spectrometry were deployed for on-line analysis of organic volatile compounds and for PM1 composition. High time resolution (down to 1-10 seconds) was chosen in order to follow the fast changes in emission patterns during acceleration and deceleration of the driving cycles. For the investigation of the atmospheric fate we deployed the simulation chamber available at IFSTTAR which is a 8m3 Teflon chamber. Atmospheric ageing was simulated using the OH radicals with cumulative concentrations corresponding to one or two days exposure in the atmosphere. In addition to the analytical approach to investigate regulated but also novel pollutants POLEMICS focused on the toxicity of the emissions. Filter extracts will be used for genotoxicity tests which are among the few in vitro tools for which values of sensitivity, specificity and predictivity of carcinogenic risk have been established. Additional studies were conducted on the oxidative potential (PO) of the emissions. The emission data obtained here will be used as input for the 0-D model, and ageing will be simulated in 0-D. The model will be modified to include newly identified precursors and to reproduce the observations and then included in air-quality platform (Polyphemus).

As the project suffered significant delays due to the dynamometer renovation in 2019 followed by containment related to COVID-19, only a few preliminary results will be mentioned here. Experimental work started 18 months late and was carried out from September to November 2020. Data analysis is underway. First trends are however observed. The Euro6d standard introduces the addition of GPF (Gasoline Particulate Filter) on gasoline direct injection vehicles, significantly reducing emissions of PN, BC and PAH. VOC emissions from petrol and diesel vehicles have significantly decreased compared to Euro5 standard vehicles, although their chemical composition has remained similar. Emissions from gasoline vehicles predominantly occurred during cold cranking and consisted primarily of monoaromatics from unburned fuel, while emissions from diesel vehicles were primarily comprised of oxidized compounds such as acids and carbonyl compounds.

As the project suffered significant delays due to the dynamometer renovation in 2019 followed by containment related to COVID-19, only a few preliminary results will be mentioned here. Experimental work started 18 months late and was carried out from September to November 2020. Data analysis is underway. First trends are however observed. The Euro6d standard introduces the addition of GPF (Gasoline Particulate Filter) on gasoline direct injection vehicles, significantly reducing emissions of PN, BC and PAH. VOC emissions from petrol and diesel vehicles have significantly decreased compared to Euro5 standard vehicles, although their chemical composition has remained similar. Emissions from gasoline vehicles predominantly occurred during cold cranking and consisted primarily of monoaromatics from unburned fuel, while emissions from diesel vehicles were primarily comprised of oxidized compounds such as acids and carbonyl compounds.

Various publications are currently in preparation: one on primary emissions, another on simulation chamber experiments (secondary aerosol formation) and two on modeling. The experimental results related to primary and secondary emissions will be presented at the European Aerosol Conference 2021.

The demand for urban mobility is steadily increasing and the growing number of vehicles in cities has major environmental consequences. Most of the urban areas in France suffer from poor air quality which results in increased morbidity and mortality rates among the urban population. Legislative authorities have tried to counteract this problem by imposing stringent emission limits on selected air pollutants, nitrogen oxides (NOx) and particulate matter (PM), which have been associated with adverse effects on human health. At the same time, modern cars are also required to produce less carbon dioxide (CO2) for reducing negative impacts on climate. Car manufacturers have responded to these emission regulations by introducing a series of in-engine modifications and exhaust after treatment technologies, e.g. the Diesel Particulate Filter (DPF) or Selective Catalytic Reduction (SCR) of NOx. New cars have nowadays to meet Euro 6 standard. In France, Euro 6 cars currently account for approximately 20% of the total fleet, with the share increasing to 40% and 60% by 2020 and 2025, respectively. Emissions of these cars are still poorly characterized, especially in view of recently discovered manipulation practices. We have recently conducted pilot emission measurements on Euro 6 passenger cars and have observed that, while emissions of pollutants subjected to regulations are indeed reduced, other non-regulated pollutants (e.g. organic nitrogen compounds and selected hydrocarbon classes) are emitted in substantial quantities. Many of the observed compounds are highly reactive in nature and will be rapidly transformed in the atmosphere potentially contributing to the formation of secondary organic aerosols (SOA). The atmospheric fate and toxicity of the mixture of pollutants emitted by Euro 6 light-duty vehicles is yet unknown.

We have gathered an interdisciplinary team composed by emission specialists, atmospheric chemists, analytical mass spectrometry experts, toxicologists and air quality modellers that proposes to investigate the nature, the fate and the impacts of Euro 6 emissions combining in laboratory and real world measurements. Car exhaust will be measured at the tailpipe and after processing in static and dynamic simulation reactors. Primary emissions and oxidation products, both in the gas and the particulate phase, will be analysed using some of the most advanced on-line mass spectrometry techniques. Complementary studies on selected chemicals found in the exhaust will be carried out for elucidating degradation mechanisms and reaction products. The obtained kinetic and product information will implement air quality models. The genotoxic potential of primary and secondary particles will be assessed using standard in vitro assays. The consortium will thus provide a first comprehensive assessment on how the transition to a Euro 6 vehicle fleet will impact urban air quality.

Project coordination

Barbara D'Anna (Laboratoire de Chimie de l'Environnement Laboratoire Chimie de l'Environnement - Mediterranean Institute of marine and terrestrial Biodiversity and Ecology)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

LTE Laboratoire Transport et Environnement
CEREA Centre d'Enseignement et de Recherche en Environnement Atmosphérique
LCE-IMBE Laboratoire de Chimie de l'Environnement Laboratoire Chimie de l'Environnement - Mediterranean Institute of marine and terrestrial Biodiversity and Ecology

Help of the ANR 460,009 euros
Beginning and duration of the scientific project: October 2018 - 36 Months

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