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• Development of an integrated modelling-measurement system to estimate harbour pollution. • The system operates near-real-time with harbour data and a low-cost sensor network. • Impact of shipping traffic and harbor-related activities is separately estimated. • The impact of harbour on NO X is that of major concern for air quality in this area. • Shipping gives the highest contribution to SO 2 and the lowest to CO compared to harbour logistics. Several studies focused on harbour impact on air quality of port-cities showing that maritime emissions could be comparable to traffic emissions of a medium-size town having relevant impact on air quality nearby the harbours. In order to plan efficient mitigation strategies, environmental and port authorities have an increasing need of reliable tools for investigating the impact of ships traffic and harbour logistics on atmospheric pollutants. In this work a system based on the integration of measurements collected using a network of low-cost on-line sensors with local scale dispersion modelling was developed. It was implemented, as a pilot action, in the information and management software of the Bari harbour (SE Italy). It can operate in near-real-time, in forecast mode, and on archived data for long-term assessments. It was tested studying the impact of the Bari harbour for the year 2018. The lowest impact was observed for CO, being the pollutant with the lowest share of the contribution of ships (between 8% and 68%) compared with the total harbour contribution. The impacts on PM 2.5 and PM 10 are larger arriving up to 11.8% of concentrations in the harbour area with an influence of shipping between 44% and 97%. The impact on SO 2 is almost solely due to ships and it arrives up to 80% in the harbour area. The impact on NO X ranges from a few percent in the urban area up to 40% in the harbour area and it is the pollutant of major concern regarding compliance with air quality standards. [ABSTRACT FROM AUTHOR]

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: PM 2.5 (aerodynamic diameter D a < 2.5 μm), PM 10 (D a < 10 μm), PM 10-2.5 (2.5 < D a < 10 μm); and PNSD in a wide range of diameters (0.01–10 μm). 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 PM 10-2.5. 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. PM 2.5 concentration was reduced by 13–44% whereas PM 10-2.5 concentration was unaffected. The concentration of accumulation mode particles followed the behaviour of PM 2.5 , with reductions of 19–57%. The results obtained could be relevant for future strategies aimed at improving air quality and understanding the processes that influence the number and mass particle size distributions. [Display omitted] • Average eBC concentration decreased by 15–20% due to COVID-19 policies. • Average concentration of quasi-ultrafine particles decreased by 20%. • Long-range transport of dust complicates the estimate of lockdown effect on coarse (PM 10-2.5) particles. • PM 2.5 concentration decreased during lockdown but PM 10-2.5 concentration was not affected. • Large reductions of concentrations of several air pollutants were observed after lockdown. [ABSTRACT FROM AUTHOR]

Exposure to atmospheric particulate matter (PM) leads to adverse health effects although the exact mechanisms of toxicity are still poorly understood. Several studies suggested that a large number of PM health effects could be due to the oxidative potential (OP) of ambient particles leading to high concentrations of reactive oxygen species (ROS). The contribution to OP of specific anthropogenic sources like road traffic, biomass burning, and industrial emissions has been investigated in several sites. However, information about the OP of natural sources are scarce and no data is available regarding the OP during Saharan dust outbreaks (SDO) in Mediterranean regions. This work uses the a-cellular DTT (dithiothreitol) assay to evaluate OP of the water-soluble fraction of PM 2.5 and PM 10 collected at an urban background site in Southern Italy. OP values in three groups of samples were compared: standard characterised by concentrations similar to the yearly averages; high carbon samples associated to combustion sources (mainly road traffic and biomass burning) and SDO events. DTT activity normalised by sampled air volume (DTT V ), representative of personal exposure, and normalised by collected aerosol mass (DTT M ), representing source-specific characteristics, were investigated. The DTT V is larger for high PM concentrations. DTT V is well correlated with secondary organic carbon concentration. An increased DTT V response was found for PM 2.5 compared to the coarse fraction PM 2.5-10 . DTT V is larger for high carbon content samples but during SDO events is statistically comparable with that of standard samples. DTT M is larger for PM 2.5 compared to PM 10 and the relative difference between the two size fractions is maximised during SDO events. This indicates that Saharan dust advection is a natural source of particles having a lower specific OP with respect to the other sources acting on the area (for water-soluble fraction). OP should be taken into account in epidemiological studies to evaluate the potential health risks associated to ROS in regions affected by high pollution events due to Saharan dust advection. [ABSTRACT FROM AUTHOR]