Overview of the French Operational Network for In Situ Observation of PM Chemical Composition and Sources in Urban Environments (CARA Program)

Abstract

The CARA program has been running since 2008 by the French reference laboratory for air quality monitoring (LCSQA) and the regional monitoring networks, to gain better knowledge—at a national level—on particulate matter (PM) chemistry and its diverse origins in urban environments. It results in strong collaborations with international-level academic partners for state-of-the-art, straightforward, and robust results and methodologies within operational air quality stakeholders (and subsequently, decision makers). Here, we illustrate some of the main outputs obtained over the last decade, thanks to this program, regarding methodological aspects (both in terms of measurement techniques and data treatment procedures) as well as acquired knowledge on the predominant PM sources. Offline and online methods are used following well-suited quality assurance and quality control procedures, notably including inter-laboratory comparison exercises. Source apportionment studies are conducted using various receptor modeling approaches. Overall, the results presented herewith underline the major influences of residential wood burning (during the cold period) and road transport emissions (exhaust and non-exhaust ones, all throughout the year), as well as substantial contributions of mineral dust and primary biogenic particles (mostly during the warm period). Long-range transport phenomena, e.g., advection of secondary inorganic aerosols from the European continental sector and of Saharan dust into the French West Indies, are also discussed in this paper. Finally, we briefly address the use of stable isotope measurements (δ15N) and of various organic molecular markers for a better understanding of the origins of ammonium and of the different organic aerosol fractions, respectively.

Modelling aerosol molecular markers in a 3D air quality model: Focus on anthropogenic organic markers

“…Quality control for the quantification of SOA markers and levoglucosan has been achieved by the analysis of the NIST standard reference material SRM 1649b (urban dust). The results obtained were in good agreement with the values available in the literature for such substances not referenced in the certificate of analysis (Albinet et al, 2019;Favez et al, 2021;Verlhac et al, 2013). Urban and suburban sites are labelled by the agglomeration names, except for SIRTA (25 km SW of Paris).…”

“…Non-ideal and ideal tests have also been performed by considering that the marker is only hydrophilic ("Hyphi" and "Hyphi ideal" tests respectively) or only hydrophobic ("Hypho" and "Hypho ideal"). The remaining 10 sites were of urban or sub-urban typologies, located in the main populated areas of France, and are part of the French operational network for in situ observation of PM chemical composition and sources in urban environments (CARA Program) (Favez et al, 2021).…”

“…OPE is a rural site, without any village or industry within several kilometers, and so not directly influenced by anthropic activities(Golly et al, 2019, description available from http://www.andra.fr). SIRTA (Site Instrumental de Recherche par Télédétection Atmospherique, 2.15° E; 48.71° N, http://sirta.ipsl.fr)(Haeffelin et al, 2005;Zhang et al, 2019) is located approximately 25 km southwest of Paris city center and is considered as representative of the background air quality of the Ile-de-France region(Favez et al, 2021;Zhang et al, 2019).…”

Impact of COVID-19 lockdown on particulate matter oxidative potential at urban backgroundversustraffic sites

“…All of these measurements were conducted following the related EN standards (i.e., EN 12341, EN 14902, EN 16909, EN 16913) and inter-laboratory comparison exercises for OC and EC within ACTRIS (Aerosols, Clouds and Trace Gases Research InfraStructure Network). Thanks to long-term observations at these given sites, as well as the presence of complementary monitoring stations in both areas, GRE (10,47,48) and BERN (49) are well-characterized in terms of ambient levels and sources of PM pollution.…”

Chemically speciated mass size distribution, particle density, shape and origin of non-refractory PM<sub>1</sub> measured at a rural background site in central Europe

“…Although measuring the seasonal variability of NR-PM 1 is becoming more common (Bressi et al, 2021), systematic studies considering chemically speciated mass size distributions are still rare. The available studies have also focused on new particle formation and growth, temporal variations, and the origin and sources of particles, including results presented from urban (Drewnick et al, 2004;Dall'Osto et al, 2009;Hersey et al, 2011;Freutel et al, 2013;Salimi et al, 2015;Kubelová et al, 2015), forestry (Allan et al, 2006), mid-altitude (Freney et al, 2011), and rural (Poulain et al, 2011;Milic et al, 2017) background environments.…”