Results of the first European Source Apportionment intercomparison for Receptor and Chemical Transport Models

In this study, the performance of the source apportionment model applications were evaluated by comparing the model results provided by 44 participants adopting a methodology based on performance indicators: z-scores and RMSEu, with pre-established acceptability criteria. Involving models based on completely different and independent input data, such as receptor models (RMs) and chemical transport models (CTMs), provided a unique opportunity to cross-validate them. In addition, comparing the modelled source chemical profiles, with those measured directly at the source contributed to corroborate the chemical profile of the tested model results. The most used RM was EPA- PMF5. RMs showed very good performance for the overall dataset (91% of z-scores accepted) and more difficulties are observed with SCE time series (72% of RMSEu accepted). Industry resulted the most problematic source for RMs due to the high variability among participants. Also the results obtained with CTMs were quite comparable to their ensemble reference using all models for the overall average (>92% of successful z-scores) while the comparability of the time series is more problematic (between 58% and 77% of the candidates’ RMSEu are accepted). In the CTM models a gap was observed between the sum of source contributions and the gravimetric PM10 mass likely due to PM underestimation in the base case. Interestingly, when only the tagged species CTM results were used in the reference, the differences between the two CTM approaches (brute force and tagged species) were evident. In this case the percentage of candidates passing the z-score and RMSEu tests were only 50% and 86%, respectively. CTMs showed good comparability with RMs for the overall dataset (83% of the z-scores accepted), more differences were observed when dealing with the time series of the single source categories. In this case the share of successful RMSEu was in the range 25% - 34%.JRC.C.5-Air and Climat

Investigating the reverse transmigration of neutrophils in human and murine in vitro models of inflammation

The aim of this project was the study of neutrophil recruitment and reverse transmigration using murine and human in vitro models of inflammation. Murine in vitro models of inflammation were developed using an immortalised microvascular cell line (MCEC-1) and primary murine vascular endothelial cells (mEC) isolated from heart and lung. We found that MCEC-1 could recruit murine neutrophils without the requirement of cytokine stimulation, although efficient transmigration did require such a stimulus. Primary cells required cytokine stimulation to recruit mEC. Interestingly, and in contrast to human EC, mEC were relatively insensitive to TNF-α stimulation, although IL-1β was a good stimulus for adhesion and migration. Using the IL-1β driven system we generated reverse migrated murine neutrophils and their phenotype and prolonged survival were assessed. The effect of shear stress and nitric oxide on the regulation of the process of reverse migration was examined. Using adoptive transfer strategies we investigated the fate of mRPMNs in vivo. A significant part of this work involved the study of human reverse migrated neutrophils at a proteomic level using two-Dimensional Fluorescence Gel Electrophoresis methodology to identify changes in neutrophils associated with reverse migration process. We found that murine reverse migrated neutrophils had a very similar surface phenotype to human reverse migrated cells. They also showed prolonged survival. However, our preliminary data on trafficking in vivo did not give a clear indication about their fate upon adoptive transfer into recipient mice. In vitro studies showed that flow generated shear stress and nitric oxide delayed, but did not inhibit, the process of reverse migration. Finally, the proteomics study revealed a number of metabolic, cytoskeletal and regulatory proteins that were differentially expressed in human reverse migrated neutrophils although the functional significance of these changes is yet to be explored

Διερεύνηση της αντίστροφης μετανάστευσης ουδετερόφιλων σε in vitro μοντέλα φλεγμονής ανθρώπινων και ποντικίσιων κυττάρων

The aim of this project was the study of neutrophil recruitment and reverse transmigration using murine and human in vitro models of inflammation. Murine in vitro models of inflammation were developed using an immortalised microvascular cell line (MCEC-1) and primary murine vascular endothelial cells (mEC) isolated from heart and lung. We found that MCEC-1 could recruit murine neutrophils without the requirement of cytokine stimulation, although efficient transmigration did require such a stimulus. Primary cells (mEC) required cytokine stimulation to recruit neutrophils. Interestingly, and in contrast to human EC, mEC were relatively insensitive to TNF-α stimulation, although IL-1β was a good stimulus for adhesion and migration. We used IL-1β to generate murine reverse migrated neutrophils (mRPMN) and their phenotype and prolonged survival were assessed. Using adoptive transfer strategies, we investigated the fate of mRPMNs in vivo. Additionally, the effect of shear stress and nitric oxide on the regulation of the process of reverse migration was examined in human in vitro models of inflammation. A significant part of this work involved the study of human reverse migrated neutrophils (RPMN) at a proteomic level using two-Dimensional Fluorescence Gel Electrophoresis methodology to identify changes in neutrophils associated with reverse migration process. We found that murine reverse migrated neutrophils had a very similar surface phenotype to human reverse migrated cells. They also showed prolonged survival. However, our preliminary data on trafficking in vivo did not give a clear indication about their fate upon adoptive transfer into recipient mice. In vitro studies showed that flow generated shear stress and nitric oxide delayed, but did not inhibit, the process of reverse migration. Finally, the proteomics study revealed a number of metabolic, cytoskeletal and regulatory proteins that were differentially expressed in human reverse migrated neutrophils although the functional significance of these changes is yet to be explored.Ο στόχος της παρούσας διδακτορικής διατριβής ήταν η μελέτη της στρατολόγησης και της αντίστροφης μετανάστευσης ουδετερόφιλων, με χρήση in vitro μοντέλων φλεγμονής από κύτταρα ποντικού και ανθρώπου. Για το σκοπό αυτό αναπτύχθηκαν in vitro μοντέλα φλεγμονής, χρησιμοποιώντας αρχικά μια αθανατοποιημένη κυτταρική σειρά μικροαγγειακών ενδοθηλιακών κυττάρων ποντικού (MCEC-1) και στη συνέχεια πρωτογενή ενδοθηλιακά κύτταρα (mEC) απομονωμένα από την καρδιά και τον πνεύμονα ποντικών. Ανακαλύψαμε ότι τα MCEC-1 μπορούσαν να στρατολογήσουν ποντικίσια ουδετερόφιλα απουσία διέγερσης με κυτταροκίνες, αν και η αποτελεσματική μετανάστευση απαιτούσε ένα τέτοιο ερέθισμα. Τα πρωτογενή κύτταρα mEC απαιτούσαν διέγερση με κυτταροκίνες για να προσελκύσουν ουδετερόφιλα. Σε αντίθεση με τα ανθρώπινα ενδοθηλιακά κύτταρα (EC), τα mEC έδειξαν ελαττωμένη ευαισθησία σε διέγερση με TNF-α, συγκριτικά με την IL-1β, η οποία μπορούσε να επάγει αρκετά αποτελεσματικά την προσκόλληση και τη μετανάστευση των ουδετερόφιλων. Χρησιμοποιώντας IL-1β για την επαγωγή οξείας φλεγμονής στα in vitro μοντέλα, συλλέξαμε ποντικίσια ουδετερόφιλα που είχαν πραγματοποιήσει αντίστροφη μετανάστευση (mRPMN) και αξιολογήθηκε ο φαινότυπος και η παρατεταμένη επιβίωσή τους. Στη συνέχεια, με τη χρήση στρατηγικών μεταφοράς κυττάρων ερευνήσαμε την τύχη των mRPMN in vivo. Παράλληλα, εξετάστηκε η επίδραση της διατμητικής τάσης και του μονοξειδίου του αζώτου στη ρύθμιση της διαδικασίας της αντίστροφης μετανάστευσης των ουδετερόφιλων με τη χρήση ενός in vitro μοντέλου φλεγμονής από ανθρώπινα κύτταρα. Ένα σημαντικό μέρος αυτής της εργασίας περιλάμβανε τη μελέτη των ανθρώπινων ουδετερόφιλων που είχαν πραγματοποιήσει αντίστροφη μετανάστευση (RPMN), σε πρωτεομικό επίπεδο με μεθοδολογία ηλεκτροφόρησης δύο διαστάσεων για τον εντοπισμό αλλαγών στα ουδετερόφιλα που σχετίζονται με τη διαδικασία αντίστροφης μετανάστευσης. Τα αποτελέσματα κατέδειξαν ότι τα ποντικίσια mRPMN είχαν παρόμοιο φαινότυπο με τα ανθρώπινα RPMN όσον αφορά συγκεκριμένους επιφανειακούς δείκτες, ενώ έδειξαν επίσης παρατεταμένη επιβίωση. Ωστόσο, τα προκαταρκτικά μας δεδομένα, όσον αφορά την in vivo κατανομή τους, δεν έδωσαν σαφή ένδειξη σχετικά με την τελική τους τύχη μετά τη μεταφορά τους σε ποντίκια-αποδέκτες. Οι μελέτες στο in vitro μοντέλο φλεγμονής από ανθρώπινα κύτταρα έδειξαν ότι η παρουσία διατμητικής τάσης και το μονοξείδιο του αζώτου καθυστέρησαν, αλλά δεν ανέστειλαν, τη διαδικασία της αντίστροφης μετανάστευσης των ουδετερόφιλων. Τέλος, η πρωτεομική ανάλυση αποκάλυψε τη διαφορική έκφραση ενός αριθμού μεταβολικών, κυτταροσκελετικών και ρυθμιστικών πρωτεϊνών στα ανθρώπινα RPMN, αν και η λειτουργική σημασία αυτών των αλλαγών δεν έχει ακόμη διερευνηθεί

PM_2.5 Source Apportionment and Implications for Particle Hygroscopicity at an Urban Background Site in Athens, Greece

Aerosol hygroscopicity is a key aerosol property, influencing a number of other physical properties, and the impacts of PM pollution on the environment, climate change, and health. The present work aims to provide insight into the contribution of major PM sources to aerosol hygroscopicity, focusing on an urban background site, with a significant impact from both primary and secondary sources. The EPA PMF 5.0 model was applied to PM2.5 chemical composition and hygroscopicity data collected from August 2016 to July 2017 in Athens, Greece. Source apportionment analysis resulted in six major sources, including four anthropogenic sources (vehicular exhaust and non-exhaust, heavy oil combustion, and a mixed source of secondary aerosol formation and biomass burning) and two natural sources (mineral dust and aged sea salt). The mixed source was found to be the main contributor to PM2.5 levels (44%), followed by heavy oil combustion (26%) and vehicular traffic exhaust and non-exhaust emissions (15%). The aerosol hygroscopic growth factor (GF) was found to be mainly associated with the mixed source (by 36%) and heavy oil combustion (by 24%) and, to a lesser extent, with vehicle exhaust (by 19%), aged sea salt (by 14%), and vehicle non-exhaust (by 6%)

Quantitative assessment of the variability in chemical profiles from source apportionment analysis of PM10 and PM2.5 at different sites within a large metropolitan area

The study aims to assess the differences between the chemical profiles of the major anthropogenic and natural PM sources in two areas with different levels of urbanization and traffic density within the same urban agglomeration. A traffic site and an urban background site in the Athens Metropolitan Area have been selected for this comparison. For both sites, eight sources were identified, with seven of them being common for the two sites (Mineral Dust, non-Exhaust Emissions, Exhaust Emissions, Heavy Oil Combustion, Sulfates & Organics, Sea Salt and Biomass Burning) and one, site-specific (Nitrates for the traffic site and Aged Sea Salt for the urban background site). The similarity between the source profiles was quantified using two statistical analysis tools, Pearson correlation (PC) and Standardized Identity Distance (SID). According to Pearson coefficients five out of the eight source profiles present high (PC > 0.8) correlation (Mineral Dust, Biomass Burning, Sea Salt, Sulfates and Heavy Oil Combustion), one presented moderate (0.8 > PC > 0.6) correlation (Exhaust) and two low/no (PC < 0.6) correlation (non-Exhaust, Nitrates/Aged Sea Salt). The source profiles that appear to be more correlated are those of sources that are not expected to have high spatial variability because there are either natural/secondary and thus have a regional character or are emitted outside the urban agglomeration and are transported to both sites. According to SID four out of the eight sources have high statistical correlation (SID < 1) in the two sites (Mineral Dust, Sea salt, Sulfates, Heavy Oil Combustion). Biomass Burning was found to be the source that yielded different results from the two methodologies. The careful examination of the source profile of that source revealed the reason for this discrepancy. SID takes all the species of the profile equally into account, while PC might be disproportionally affected by a few numbers of species with very high concentrations. It is suggested, based on the findings of this work, that the combined use of both tools can lead the users to a thorough evaluation of the similarity of source profiles. This work is, to the best of our knowledge, the first time a study is focused on the quantitative comparison of the source profiles for sites inside the same urban agglomeration using statistical indicators.JRC.C.5-Air and Climat

Estimation of the personal deposited dose of particulate matter and particle-bound metals using data from selected European cities

Summarization: The present study focused on the estimation of the personal dose of airborne particles using an exposure dose model (ExDoM2). Input data from three European cities (Athens, Kuopio, Lisbon) were selected to implement the model that calculates the deposited dose and retention of particles in the respiratory tract, the mass transferred to the oesophagus and the absorption to blood as well as the dose for five particle-bound metals. Model results showed that after one day exposure higher deposited dose in the respiratory tract was obtained for Lisbon as a direct consequence of the higher PM concentration measured in this city. Moreover, the activity profile and the physical characteristics of the exposed subject had strong impact on the estimated deposited dose. Thus, light activity corresponded to higher deposited dose compared to no activity as well as an adult male exhibited higher dose, both findings associated with increased inhalation rate. Regarding the internal dose for particle-bound metals higher dose for four out of the five metals was obtained in lungs followed by the muscles for As, the gastrointestinal tract for Cr, the other tissues for Mn, the intestines for Cd and finally for Pb higher dose was found in bones and blood.Presented on: Atmospher

A new methodology to assess the performance and uncertainty of source apportionment models II: The results of two European intercomparison exercises

The performance and the uncertainty of receptor models (RMs) were assessed in intercomparison exercises employing real-world and synthetic input datasets. To that end, the results obtained by different practitioners using ten different RMs were compared with a reference. In order to explain the differences in the performances and uncertainties of the different approaches, the apportioned mass, the number of sources, the chemical profiles, the contribution-to-species and the time trends of the sources were all evaluated using the methodology described in Belis et al. (2015). In this study, 87% of the 344 source contribution estimates (SCEs) reported by participants in 47 different source apportionment model results met the 50% standard uncertainty quality objective established for the performance test. In addition, 68% of the SCE uncertainties reported in the results were coherent with the analytical uncertainties in the input data. The most used models, EPA-PMF v.3, PMF2 and EPA-CMB 8.2, presented quite satisfactory performances in the estimation of SCEs while unconstrained models, that do not account for the uncertainty in the input data (e.g. APCS and FA-MLRA), showed below average performance. Sources with well-defined chemical profiles and seasonal time trends, that make appreciable contributions (>10%), were those better quantified by the models while those with contributions to the PM mass close to 1% represented a challenge. The results of the assessment indicate that RMs are capable of estimating the contribution of the major pollution source categories over a given time window with a level of accuracy that is in line with the needs of air quality management.JRC.H.2-Air and Climat

Impact of 2020 COVID-19 lockdowns on particulate air pollution across Europe

International audienceAbstract. To fight against the first wave of coronavirus disease 2019 (COVID-19) in 2020, lockdown measures were implemented in most European countries. These lockdowns had well-documented effects on human mobility. We assessed the impact of the lockdown implementation and relaxation on air pollution by comparing daily particulate matter (PM), nitrogen dioxide (NO2) and ozone (O3) concentrations, as well as particle number size distributions (PNSDs) and particle light absorption coefficient in situ measurement data, with values that would have been expected if no COVID-19 epidemic had occurred at 28 sites across Europe for the period 17 February–31 May 2020. Expected PM, NO2 and O3 concentrations were calculated from the 2020 Copernicus Atmosphere Monitoring Service (CAMS) ensemble forecasts, combined with 2019 CAMS ensemble forecasts and measurement data. On average, lockdown implementations did not lead to a decrease in PM2.5 mass concentrations at urban sites, while relaxations resulted in a +26 ± 21 % rebound. The impacts of lockdown implementation and relaxation on NO2 concentrations were more consistent (−29 ± 17 and +31 ± 30 %, respectively). The implementation of the lockdown measures also induced statistically significant increases in O3 concentrations at half of all sites (+13 % on average). An enhanced oxidising capacity of the atmosphere could have boosted the production of secondary aerosol at those places. By comparison with 2017–2019 measurement data, a significant change in the relative contributions of wood and fossil fuel burning to the concentration of black carbon during the lockdown was detected at 7 out of 14 sites. The contribution of particles smaller than 70 nm to the total number of particles significantly also changed at most of the urban sites, with a mean decrease of −7 ± 5 % coinciding with the lockdown implementation. Our study shows that the response of PM2.5 and PM10 mass concentrations to lockdown measures was not systematic at various sites across Europe for multiple reasons, the relationship between road traffic intensity and particulate air pollution being more complex than expected