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This study aims to picture the phenomenology of urban ambient total lung deposited surface area (LDSA) (including head/throat (HA), tracheobronchial (TB), and alveolar (ALV) regions) based on multiple path particle dosimetry (MPPD) model during 2017-2019 period collected from urban background (UB, n = 15), traffic (TR, n = 6), suburban background (SUB, n = 4), and regional background (RB, n = 1) monitoring sites in Europe (25) and USA (1). Briefly, the spatial-temporal distribution characteristics of the deposition of LDSA, including diel, weekly, and seasonal patterns, were analyzed. Then, the relationship between LDSA and other air quality metrics at each monitoring site was investigated. The result showed that the peak concentrations of LDSA at UB and TR sites are commonly observed in the morning (06:00-8:00 UTC) and late evening (19:00-22:00 UTC), coinciding with traffic rush hours, biomass burning, and atmospheric stagnation periods. The only LDSA night-time peaks are observed on weekends. Due to the variability of emission sources and meteorology, the seasonal variability of the LDSA concentration revealed significant differences (p = 0.01) between the four seasons at all monitoring sites. Meanwhile, the correlations of LDSA with other pollutant metrics suggested that Aitken and accumulation mode particles play a significant role in the total LDSA concentration. The results also indicated that the main proportion of total LDSA is attributed to the ALV fraction (50 %), followed by the TB (34 %) and HA (16 %). Overall, this study provides valuable information of LDSA as a predictor in epidemiological studies and for the first time presenting total LDSA in a variety of European urban environments.

The 2017-2019 hourly particle number size distributions (PNSD) from 26 sites in Europe and 1 in the US were evaluated focusing on 16 urban background (UB) and 6 traffic (TR) sites in the framework of Research Infrastructures services reinforcing air quality monitoring capacities in European URBAN & industrial areaS (RI-URBANS) project. The main objective was to describe the phenomenology of urban ultrafine particles (UFP) in Europe with a significant air quality focus. The varying lower size detection limits made it difficult to compare PN concentrations (PNC), particularly PN10-25, from different cities. PNCs follow a TR > UB > Suburban (SUB) order. PNC and Black Carbon (BC) progressively increase from Northern Europe to Southern Europe and from Western to Eastern Europe. At the UB sites, typical traffic rush hour PNC peaks are evident, many also showing midday-morning PNC peaks anti-correlated with BC. These peaks result from increased PN10-25, suggesting significant PNC contributions from nucleation, fumigation and shipping. Site types to be identified by daily and seasonal PNC and BC patterns are: (i) PNC mainly driven by traffic emissions, with marked correlations with BC on different time scales; (ii) marked midday/morning PNC peaks and a seasonal anti-correlation with PNC/BC; (iii) both traffic peaks and midday peaks without marked seasonal patterns. Groups (ii) and (iii) included cities with high insolation. PNC, especially PN25-800, was positively correlated with BC, NO2, CO and PM for several sites. The variable correlation of PNSD with different urban pollutants demonstrates that these do not reflect the variability of UFP in urban environments. Specific monitoring of PNSD is needed if nanoparticles and their associated health impacts are to be assessed. Implementation of the CEN-ACTRIS recommendations for PNSD measurements would provide comparable measurements, and measurements of <10 nm PNC are needed for full evaluation of the health effects of this si

The Sydney Particle Study involved the comprehensive measurement of meteorology, particles and gases at a location in western Sydney during February–March 2011 and April–May 2012. The aim of this study was to increase scientific understanding of particle formation and transformations in the Sydney airshed. In this paper we describe the methods used to collect and analyse particle and gaseous samples, as well as the methods employed for the continuous measurement of particle concentrations, particle microphysical properties, and gaseous concentrations. This paper also provides a description of the data collected and is a metadata record for the data sets published in Keywood et al. (2016a, https://doi.org/10.4225/08/57903B83D6A5D) and Keywood et al. (2016b, https://doi.org/10.4225/08/5791B5528BD63).

The Sydney Particle Study involved the comprehensive measurement of meteorology, particles and gases at a location in western Sydney during February-March 2011 and April-May 2012. The aim of this study was to increase scientific understanding of particle formation and transformations in the Sydney airshed. In this paper we describe the methods used to collect and analyse particle and gaseous samples, as well as the methods employed for the continuous measurement of particle concentrations, particle microphysical properties, and gaseous concentrations. This paper also provides a description of the data collected and is a metadata record for the data sets published in Keywood et al. (2016a, line"https://doi.org/10.4225/08/57903B83D6A5D">https://doi.org/10.4225/08/57903B83D6A5D) and Keywood et al. (2016b, line"https://doi.org/10.4225/08/5791B5528BD63">https://doi.org/10.4225/08/5791B5528BD63).

The Jing Ltd. miniature combustion aerosol standard (Mini- CAST) soot generator is a portable, commercially available burner that is widely used for laboratory measurements of soot processes. While many studies have used the Mini-CAST to generate soot with known size, concentration, and organic carbon fraction under a single or few conditions, there has been no systematic study of the burner operation over a wide range of operating conditions. Here, we present a comprehensive characterization of the microphysical, chemical, morphological, and hygroscopic properties of Mini- CAST soot over the full range of oxidation air and mixing N2 flow rates. Very fuel-rich and fuel-lean flame conditions are found to produce organic-dominated soot with mode diameters of 10–60 nm, and the highest particle number concentrations are produced under fuel-rich conditions. The lowest organic fraction and largest diameter soot (70–130 nm) occur under slightly fuel-lean conditions. Moving from fuel-rich to fuel-lean conditions also increases the O:C ratio of the soot coatings from ~0.05 to ~0.25, which causes a small fraction of the particles to act as cloud condensation nuclei near the Kelvin limit (κ ~ 0–10−3). Comparison of these property ranges to those reported in the literature for aircraft and diesel engine soots indicates that the Mini-CAST soot is similar to real-world primary soot particles, which lends itself to a variety of process-based soot studies. The trends in soot properties uncovered here will guide selection of burner operating conditions to achieve optimum soot properties that are most relevant to such studies.

En Afrique de l'ouest, trois types d'aérosols prédominent : les poussières désertiques, les aérosols de feu de biomasse et les sels marins. Le mélange de ces trois types de particules d'aérosols peut impacter à divers degrés les propriétés radiatives de l'atmosphère ainsi que la formation et la précipitation des nuages. Dans le cadre de la campagne de mesures AMMA (Analyse Multidisciplinaire de la Mousson Africaine) et pour caractériser au mieux ces particules, une veine de prélèvement ainsi qu'une plate-forme instrumentale ont été développés et implémentées dans un avion de recherche, l'ATR-42. Deux cas d'étude ont été sélectionnés, en juillet (SOP1) et en août (SOP2) 2006 afin de comprendre l'impact des systèmes convectif de méso-échelle (MCS) sur les propriétés hygroscopiques des aérosols. Les résultats des observations montrent une augmentation des propriétés hygroscopiques des particules due à la présence d'une pellicule de surface composée d'éléments solubles (sulfate, nitrate et chlorure). De façon à mettre en évidence les processus responsables de ces modifications, une simulation numérique a été réalisée. Cette simulation permet de décrire le mélange qui s'opère en phase aqueuse entre des éléments solubles et des poussières désertiques lesquelles, après évaporation, se recouvrent d'une pellicule de surface avant d'être réinjectées dans l'atmosphère., In West Africa, three types of aerosols prevail: desert dusts, biomass burning particles and sea salts. The mixing of these three types of particles may have consequences on atmospheric radiative properties and on cloud formation and precipitation. Within the framework of AMMA (African Monsoon Multidisciplinary Analyses) and to better characterize these particles, an isokinetic inlet as well as an instrumental platform were developed and deployed in the French research aircraft (ATR-42). Two study cases (July SOP1 and August SOP2 2006) illustrate the impact of the meso-scale convective systems (MCS) on the hygroscopic properties of particles. The observed results show an increase of particle hygroscopic properties due to the coating of soluble elements (sulfate, nitrate and chloride). Then, the simulation of the first study case shows the mixing of soluble elements and desert dusts in aqueous phase (i.e. cloud droplets). After evaporation, dust particles coated with soluble elements are released in the atmosphere.