The water-soluble fraction of particulate matter (PM) is the most bio-accessible and potentially harmful component due to its ability to be absorbed through the respiratory tract. This study evaluates the content of water-soluble organic carbon (WSOC) and water-soluble total nitrogen (WSTN) in PM2.5 and PM10 filters collected in the Lecce area (Italy), focusing on monthly samples from different site typologies and daily samples from a single background site. WSOC was quantified using two methods on aqueous extracts with a TOC-L CPH analyser: (1) the total organic carbon (TOC) method, which determines WSOC as the difference between total carbon (TC) and inorganic carbon (IC); and (2) the non-purgeable organic carbon (NPOC) method, which removes inorganic carbon by acidification and air purging before TC measurement. The analytical parameters of the NPOC method were optimized using a Design of Experiment (DoE), while WSTN, equivalent to total soluble nitrogen in the extract, was measured simultaneously using the NPOC method in N-mode. Results showed a strong correlation and high consistency between the two WSOC methods, with overall combined averages of WSOCTOC = (3.3 +/- 0.5) mu g/m3 and WSOCNPOC = (3.2 +/- 0.4) mu g/m3. OC solubility was high and similar in both PM fractions, averaging 65 % in PM2.5 and 66 % in PM10 but demonstrated a clear seasonal variability, with higher WSOC/OC ratios in the cold season. Furthermore, the NPOC approach facilitates the simultaneous quantification of WSTN with a reduced sample volume, and the data confirmed the limited content of watersoluble organic nitrogen (WSON) in this dataset, thus enhancing analytical efficiency for routine monitoring.

Several research efforts were devoted to investigate long-term trends of carbonaceous aerosols in atmospheric particulate matter. Carbon is known to affect climate, human health, and cultural heritage being an important component also for planning future policies. This work investigates the longest dataset of carbon content (EC and OC) in PM2.5 and PM10 fractions available in south Italy (2015-2022). Equivalent black carbon (eBC) was determined hourly in PM10, using the multi-angle absorption photometer (MAAP), and it was used to evaluate the trend of the mass absorption coefficient (MAC) determined in-situ. PM2.5 and its OC and EC content showed a statistically significant decreasing trend throughout years, since 2017-2018, approximately-5 % yr(-1), falling in the ranges reported for other urban background sites in Europe. The decrease of PM10 and its carbon content was more limited, approximately-2 % yr-1 but it was not statistically significant (p > 0.05). Temporal analysis revealed that seasonality played the most significant role in concentration pattern of PM and carbonaceous species, including secondary organic aerosol (SOC) and EC/OC ratio, compared to weekly or daily variabilities, with the highest daily values in winter/autumn. This was likely due to the contributions of biomass burning (for domestic heating and agricultural practices) and of road traffic both larger at this site during the autumn/winter. The value of MAC in-situ was 12.4 f 1.2 m2g(-1) (as geometric mean f standard deviation) or 12.6 f 2.5 m2g(-1) (as arithmetic mean f standard deviation), showing a slight increase during summer and early autumn compared to the other season. MAC showed an increasing long-term trend of 2.5 % yr(-1).

Carbonaceous aerosols represent a significant component of atmospheric aerosol, with implications for climate and human health. The recent EU Directive 2024/2881 highlights the need to monitor emerging pollutants like black carbon more effectively. This study presents an brief field campaign at an urban background site aimed at characterizing carbonaceous aerosols. Daily samples of PM10 and PM2.5 were analyzed using a Sunset thermal-optical analyzer to determine organic and elemental carbon (OC, EC), while real-time equivalent black carbon (eBC) was measured with three independent instruments: MAAP, AE33, and Giano BC1. Total carbon (TC) was monitored using an online TCA08 thermo-catalytic analyzer. The average concentration of PM10 was 17.1 µg/m3 and 10.4 µg/m3 for PM2.5. On average, OC and EC represented 16.5% and 3.6% of PM10 mass, and 22.6% and 5.5% of PM2.5. SOC accounted for 36% of OC. The in situ Mass Absorption Cross-section (MAC), recalculated for the ECO site, was between 8.0 and 12.2 m2/g. eBC concentrations were modulated by the daily evolution of the planetary boundary-layer height and combustion sources. The apportionment of eBC was 65% from fossil fuel and 35% from biomass burning. Biomass-burning emissions were further confirmed by optical measurements, with BrC contributing 35% of absorption at 370 nm.

Oxidative potential (OP) is a potential indicator of negative health effects of particulate matter (PM). To address mitigation strategies, there is need of understanding how natural and anthropogenic sources influence OP at different sites. This work investigates spatial and seasonal variabilities of PM2.5 and PM10 concentrations, composition, and oxidative potential (OPDTTV, obtained with DTT assay), simultaneously at 22 sites in a central Mediterranean area in south Italy. Source apportionment using PMF5 allowed to evaluate the contributions of eight sources: traffic, biomass burning (BB), nitrate, sulphate-rich, marine, crustal, carbonates/construction, and industrial (only for PM2.5). Nitrate, traffic, and BB had larger contributions during the cold season and presented spatial variability with exclusion of nitrate. Industrial contributions did not have relevant seasonal or spatial variability. The other sources had an opposite trend with larger values during the warm season but only sulphate-rich had non-negligible spatial variability. OPDTTV had relevant spatial variability only during the cold season. Four sources had statistically significant contributions to OPDTTV: traffic, BB, sulphate-rich, and crustal (in descending order). The use of soluble and insoluble fractions of OC and Ca in PMF5 allowed a better separation between traffic and BB sources and allowed to determine the role of local construction works. The results may have implications in future policies for mitigation strategies of OP targeting specific sources categories.

Abstract. Energy-dispersive X-ray fluorescence (ED-XRF) is a versatile non-destructive technique to evaluate elemental composition of atmospheric particulate matter (PM) without the need for sample preparation and with high potentiality in source apportionment studies. It is usually applied on Teflon or polycarbonate substrates; however, it would be preferable to use quartz substrates for the possibility to use the same substrate also for carbon detection. In this work an intercomparison among five laboratories on PM10 samples collected on Teflon and quartz filters was done with the specific purpose of understanding the performance of the ED-XRF technique applied to samples collected on quartz substrates. Limits of detection (LODs) on quartz substrates were significantly larger than those on Teflon for the majority of the elements with the exclusion of Cl, Mn, Cu, and Rb, which had comparable LODs for the two substrates. Repeatability on PM10 samples collected on quartz and Teflon substrates was comparable and, on average, better than 10 % for the majority of the elements analysed and better than 5 % for several elements. Comparisons of analysis on Teflon filters for 20 elements obtained by the different laboratories were in the range of ±15 % of the 1:1 line for most of the elements and laboratories. Comparison of measurements on samples collected on quartz and Teflon substrates showed that 17 elements were well correlated (R > 0.7) with average Cquartz/CTeflon ratios in the range 0.6 ± 0.1 (for light elements, due to self-absorption effects) to 1.1 ± 0.1 for the majority of the cases. This suggested that reasonable results could be obtained on quartz substrates for 17 elements, including Na, Mg, and Al, using calibration on Teflon and the ratios Cquartz/CTeflon as correction factors. However, these correction factors were dependent on the instrument and method used for the analysis.

This study targets to determine the oxidative potential (OP) of fine aerosols in an urban-industrial area of the Lisbon Metropolitan Area (Portugal) and, in addition, to identify which pollution sources may have an impact on the OP levels of fine aerosols. For this purpose, thirty samples were selected from a set of 128 samples collected over one year (Dec 2019-Nov 2020), based on the highest load for each source (both mass and OP_V^DTT ) showed to have a significant positive association with PM2.5 levels (R2 = 0.714). Considering that the mass contributions of the different sources to the PM2.5 levels were known, Spearman correlations were assessed and significant correlations were found between OP_V^DTT and three different sources: vehicle exhaust (ρ = 0.647, p-value = 0.001), fuel-oil combustion (ρ = 0.523, p-value = 0.012) and industry (ρ = 0.463, p-value = 0.018). Using a multiple linear regression analysis, these three sources were found to explain 82 OP_V^DTT , with vehicle exhaust being the most influential source.

Atmospheric particulate matter (PM) is one of the major risks for global health. The exact mechanisms of toxicity are still not completely understood leading to contrasting results when different toxicity metrics are compared. In this work, PM10 was collected at three sites for the determination of acellular oxidative potential (OP), intracellular oxidative stress (OSGC), cytotoxicity (MTT assay), and genotoxicity (Comet assay). The in vitro tests were done on the A549 cell line. The objective was to investigate the correlations among acellular and intracellular toxicity indicators, the variability among the sites, and how these correlations were influenced by the main sources by using PMF receptor model coupled with MLR. The OPDTTV, OSGCV, and cytotoxicity were strongly influenced by combustion sources. Advection of African dust led to lower-than-average intrinsic toxicity indicators. OPDTTV and OSGCV showed site-dependent correlations suggesting that acellular OP may not be fully representative of the intracellular oxidative stress at all sites and conditions. Cytotoxicity correlated with both OPDTTV and OSGCV at two sites out of three and the strength of the correlation was larger with OSGCV. Genotoxicity was correlated with cytotoxicity at all sites and correlated with both, OPDTTV and OSGCV, at two sites out of three. Results suggest that several toxicity indicators are useful to gain a global picture of the potential health effects of PM.

Many countries imposed lockdown (LD) to limit the spread of COVID-19, which led to a reduction in the emission of anthropogenic atmospheric pollutants. Several studies have investigated the effects of LD on air quality, mostly in urban settings and criteria pollutants. However, less information is available on background sites, and virtually no information is available on particle number size distribution (PNSD). This study investigated the effect of LD on air quality at an urban background site representing a near coast area in the central Mediterranean. The analysis focused on equivalent black carbon (eBC), particle mass concentrations in different size fractions: PM2.5 (aerodynamic diameter Da < 2.5 mu m), PM10 (Da < 10 mu m), PM10-2.5 (2.5 < Da < 10 mu m); and PNSD in a wide range of diameters (0.01-10 mu m). Measurements in 2020 during the national LD in Italy and period immediately after LD (POST-LD period) were compared with those in the corresponding periods from 2015 to 2019. The results showed that LD reduced the frequency and intensity of high-pollution events. Reductions were more relevant during POST-LD than during LD period for all variables, except quasi-ultrafine particles and PM10-2.5. Two events of long-range transport of dust were observed, which need to be identified and removed to determine the effect of LD. The decreases in the quasi-ultrafine particles and eBC concentrations were 20%, and 15-22%, respectively. PM2.5 concentration was reduced by 13-44% whereas PM10-2.5 concentration was unaffected. The concentration of accumulation mode particles followed the behaviour of PM2.5, with

Airborne particulate matter (PM) is studied because of its effects on human health and climate change. PM long-term characterisation allows identifying trends and evaluating the outcomes of environmental protection pol-icies. This work is aimed to study the inter-annual variability of PM2.5 and PM10 concentrations and chemical composition in an urban background site (Italy). A dataset of daily PM2.5 and PM10 was collected in the period 2016-2017, including the content of OC, EC, major water-soluble ions, main metals, and compared to a similar dataset collected in the period 2013-2014. Oxidative potential using DTT assay (dithiothreitol) was evaluated and expressed in DTTV as 0.39 nmol/min.m(3) in PM10 and 0.29 in PM2.5 nmol/min.m(3). PM source apportionment was computed using the EPA PMF5.0 model and source contributions compared with those of a previous dataset collected between 2013 and 2014. Multi linear regression analysis identified which source contributed (p < 0.05) to the oxidative potential of each size fraction. Inter-annual trends were more evident on PM2.5 with reductions of biomass burning contribution and increases in traffic contribution in the 2016-2017 period. Crustal contri-butions were similar for the two periods, in both size fractions. Carbonates were comparable in PM10 with a slight increase in PM2.5. Sea spray decreased in PM10. The DTTV of PM2.5 peaked during cold periods, while, the DTTV of the PM10-2.5 fraction peaked in summer, suggesting that different sources, with different seasonality, influence OP in the PM2.5 and PM10-2.5 fractions. Analysis showed that sea spray, crustal, and carbonates sources contribute-13.6% to DTTV in PM2.5 and-62.4% to DTTV in PM10-2.5. Combustion sources (biomass burning and traffic) contribute to the majority of DTTV (50.6%) in PM2.5 and contribute for-26% to DTTV in PM10-2.5. Secondary nitrate contributes to DTTV in both fine and coarse fraction; secondary sulphate contribute to DTTV in PM2.5 with negligible contributions to DTTV in PM10-2.5.

International shipping is growing worldwide for both, commercial and tourist reasons, making harbors key contributors to social and economic development worldwide. However, emissions of atmospheric pollutants from ships have standards and controls that are far less stringent than those of land emission sources. This raised concerns regarding potential impact of ship emissions to air quality, human health, and climate, especially in highly populated coastal areas. This work reviews the current knowledge regarding the impacts of shipping to emissions, contributions to atmospheric concentrations of gaseous and particulate matter criteria and non-criteria pollutants, and impacts to health indicators. The effects of the evolution of legislation standards, relative to sulfur content in marine fuels and enforcement of Emission Control Areas (ECAs), on pollution associated with shipping is discussed putting in evidence the long-term trends. Furthermore, future perspectives and projections related to the increase of energy efficiency of ships and improvement on quality of fuels will be discussed.

Populated coastal areas are exposed to emissions from harbour-related activities (ship traffic, loading/unloading, and internal vehicular traffic), posing public health issues and environmental pressures on climate. Due to the strategic geographical position of Italy and the high number of ports along coastlines, an increasing concern about maritime emissions from Italian harbours has been made explicit in the EU and IMO (International Maritime Organization, London, UK) agenda, also supporting the inclusion in a potential Mediterranean emission control area (MedECA). This work reviews the main available outcomes concerning shipping (and harbours') contributions to local air quality, particularly in terms of concentration of particulate matter (PM) and gaseous pollutants (mainly nitrogen and sulphur oxides), in the main Italian hubs. Maritime emissions from literature and disaggregated emission inventories are discussed. Furthermore, estimated impacts to air quality, obtained with dispersion and receptor modeling approaches, which are the most commonly applied methodologies, are discussed. Results show a certain variability that suggests the necessity of harmonization among methods and input data in order to compare results. The analysis gives a picture of the effects of this pollution source, which could be useful for implementing effective mitigation strategies at a national level.

The aim of this work was characterization of airborne particulates in the port city of Rijeka in order to evaluate impact of ship emissions on air quality. Samples of airborne particulates were collected with a ten stages cascade impactor during two campaigns: autumn and spring. A total of 16 weekly samples were analyzed on mass concentration, ions, metals and carbonaceous species (EC, OC, WSOC). Distribution of airborne fractions showed a bimodal distribution, with two maxima: one in coarse, and other in fine fraction. Source apportionment using PMF receptor model identified six sources of airborne particulates in Rijeka: crustal, biomass burning, sea salt, traffic/metal industry, combustion/SIA and HFO burning, i.e., ship emission (contribution 3%). The contribution of ship traffic to primary emission of particulate matter, using vanadium as tracer, indicated a twofold increase for PM10 and PM2.5 relative to 2012?14. An unusual desert dust event was registered in autumn campaign.

The increase of global commerce and tourism makes the shipping sector an important contributor of atmospheric particles and gaseous pollutants. These have impacts on both health and climate, especially in populated coastal areas. Maritime activities could be an important driver for economic and social development, however, they are also an environmental pressure. Several policies were implemented in the last decades, at local/regional or international levels, mainly focused on reducing the content of sulphur in marine fuels. The last international IMO-2020 regulation was enforced on 1 January 2020. This work reviews some recent studies on this topic delineating current knowledge of the impacts of maritime emissions on air quality and health and the future projections relative to the benefits of the implementation of the new IMO-2020 regulation. In addition, future perspectives for further mitigation strategies are discussed.

A source apportionment study was performed on PM10 samples collected in four sites nearby the largest Italian coal-fired power plant (SE Italy). A multi-model approach, based on integration of receptor (Positive Matrix Factorization - PMF, Chemical Mass Balance - CMB) and dispersion (CALPUFF) models, estimated the contribution of the power plant to primary PM10 and to secondary ammonium sulphate. Maximum PM10 daily concentrations were observed at all sites during winter period, with exceedances of the daily legislation threshold mainly due to biomass burning and road traffic. Chemical analysis explained about 55% of PM10 in the Brindisi area, 62% in the Lecce area. Eight PM sources were identified: crustal and power plant, resuspended dust, traffic, secondary ammonium sulphate, secondary nitrate, marine, biomass burning and harbour – industrial, with a reasonable comparability between receptor models outputs. Combining the information from receptor and dispersion models, the average contribution of the power plant to primary PM10 was 2% (±1%) of PM10 for Lecce site and 3% (±1%) as average of the three sites of Brindisi province. The contribution to secondary ammonium sulphate was ranging between 1.3% (±0.3%) of PM10 and 1.7% (±0.4%). These results were compared with those obtained using the same approach in the area close to Torrevaldaliga Nord (TVN) coal-fired power plant. Results indicate a lower primary contribution to PM10 of the TVN station, likely associated to lower PM emissions at the stack of TVN station and different heights of release, comparable contributions to secondary ammonium sulphate founded.

Shipping contributions to atmospheric particulate matter were estimated by an approach based on high temporal resolution measurements of mass and number size distribution, correlated with meteorological and ship movements data, in two Adriatic harbours. Trends of contributions are discussed. Contribution to particle number concentrations (PNC) was 3–4 times larger than that to PM2.5. In Venice, strategies for reduction of shipping emissions were effective in lowering the PM2.5 primary impact, while PNC contribution was significant in Brindisi. The maximum contribution was found to ultrafine particles (UFP), followed by a minimum at diameters between 1 and 1.5 µm and a growth in the coarse range.

• Chemical characterisation of aerosol was performed in 12 size ranges. • Source apportionment of Venice size-segregated aerosol was carried out. • Impact of ship traffic was studied for the first time on particles below 1 μm. • Impact of ship traffic is higher in nanoparticles compared to larger particles.

Detailed information on in-harbour shipping contribution to size segregated particles in coastal cities are scarce, especially in the busy Mediterranean basin. This poses issues for human exposure and air quality in urban harbour agglomerates, where only criteria pollutants (i.e. PM10 and/or PM2.5) are usually monitored. In this work, particle number and mass size distributions, in a large size range (0.01-31 μm), were obtained in two coastal cities of northern Adriatic Sea: Venice (Italy) and Rijeka (Croatia). Three size ranges were investigated: nanoparticles (diameter D < 0.25 μm); fine particles (0.25 1 μm). Absolute concentrations were larger in Venice for all size ranges showing, using analysis of daily trends, a large influence of local meteorology and boundary-layer dynamics. Contribution of road transport was larger (in relative terms) in Rijeka compared to Venice. The highest contributions of shipping were in Venice, mainly because of the larger ship traffic. Maximum impact was on nanoparticles 7.4% (Venice) and 1.8% (Rijeka), the minimum was on fine range 1.9% (Venice) and <0.2% (Rijeka) and intermediate values were found in the coarse fraction 1.8% (Venice) and 0.5% (Rijeka). Contribution of shipping to mass concentration was not distinguishable from uncertainty in Rijeka (<0.2% for PM1, PM2.5, and PM10) and was about 2% in Venice. Relative contributions as function of particles size show remarkable similitudes: a maximum for nanoparticles, a quick decrease and a successive secondary maximum (2-3 times lower than the first) in the fine range. For larger diameters, the relative contributions reach a minimum at 1-1.5 μm and there is a successive increase in the coarse range. Size distributions showed a not negligible contribution of harbour emissions to nanoparticle and fine particle number concentrations, compared to PM2.5 or PM10, indicating them as a better metric to monitor shipping impacts compared to mass concentrations (PM2.5 or PM10).