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In early 2020, SARS-CoV-2 was declared a pandemic by the WHO and Italy was one of the first and most severely affected country in Europe. Despite the global interest about COVID-19 pandemic, several aspects of this infection are still unclear, especially in pediatric population. This study aims to investigate the characteristics of the isolated or quarantined children and adolescents followed by the Public Health Department of the Italian province of Modena during the first wave of COVID-19.The study population included all non-adult subjects aged 0-18 years who underwent isolation or quarantine during the first wave of SARS-CoV-2 pandemic from February 24 to June 18, 2020 in Modena province, Northern Italy.In Modena province, 1230 children and adolescents were isolated in case of SARS-CoV-2 infection (6.3%), or quarantined due to close contact with confirmed cases (88.7%) or travelling from a high-risk area (5.0%). Among 349 individuals who underwent swab testing, 294 (84.2%) reported close contact with an infected cohabiting relative and 158 (45.3%) were symptomatic. Among all tested subjects, 78 (22.4%) resulted positive, with a higher proportion of symptomatic subjects compared with the SARS-CoV-2-negative (78.2% vs. 35.8%). Fever was mostly present in SARS-CoV-2-positive children (48.7% vs. 12.6%). Both anosmia (58.3% vs. 41.7%) and dysgeusia (54.5% vs. 45.5%) had only slightly higher frequency in SARS-CoV-2-positive.These findings allow to expand the knowledge regarding characteristics of non-adult subjects isolated or quarantined during the first wave of SARS-CoV-2 pandemic. (www.actabiomedica.it).

Acidity profoundly affects almost every aspect that shapes the composition of ambient particles and their environmental impact. Thermodynamic analysis of gas-particle composition datasets offers robust estimates of acidity, but they are not available for long periods of time. Fog composition datasets, however, are available for many decades; we develop a thermodynamic analysis to estimate the ammonia in equilibrium with fog water and to infer the pre-fog aerosol pH starting from fog chemical composition and pH. The acidity values from the new method agree with the results of thermodynamic analysis of the available gas-particle composition data. Applying the new method to historical (25 years) fog water composition at the rural station of San Pietro Capofiume (SPC) in the Po Valley (Italy) suggests that the aerosol has been mildly acidic, with its pH decreasing by 0.5–1.5 pH units over the last decades. The observed pH of the fog water also increased 1 unit over the same period. Analysis of the simulated aerosol pH reveals that the aerosol acidity trend is driven by a decrease in aerosol precursor concentrations, and changes in temperature and relative humidity. Currently, NOx controls would be most effective for PM2.5 reduction in the Po valley both during summer and winter. In the future, however, seasonal transitions to the NH3-sensitive region may occur, meaning that the NH3 reduction policy may become increasingly necessary., Paglione, M., Decesari, S., Rinaldi, M., Tarozzi, L., Manarini, F., Gilardoni, S., Facchini, M. C., Fuzzi, S., Bacco, D., Trentini, A., Pandis S. N., and Nenes A. : Historical Changes in Seasonal Aerosol Acidity in the Po Valley (Italy) as Inferred from Fog Water and Aerosol Measurements, Environ. Sci. Technol., May 17, 2021, https://doi.org/10.1021/acs.est.1c00651

The aerosol size-segregated chemical composition was analyzed at an urban (Bologna) and a rural (San Pietro Capofiume) site in the Po Valley, Italy, during June and July 2012, by ion-chromatography (major water-soluble ions and organic acids) and evolved gas analysis (total and water-soluble carbon), to investigate sources and mechanisms of secondary aerosol formation during the summer. A significant enhancement of secondary organic and inorganic aerosol mass was observed under anticyclonic conditions with recirculation of planetary boundary layer air but with substantial differences between the urban and the rural site. The data analysis, including a principal component analysis (PCA) on the size-resolved dataset of chemical concentrations, indicated that the photochemical oxidation of inorganic and organic gaseous precursors was an important mechanism of secondary aerosol formation at both sites. In addition, at the rural site a second formation process, explaining the largest fraction (22 %) of the total variance, was active at nighttime, especially under stagnant conditions. Nocturnal chemistry in the rural Po Valley was associated with the formation of ammonium nitrate in large accumulation-mode (0.42–1.2 µm) aerosols favored by local thermodynamic conditions (higher relative humidity and lower temperature compared to the urban site). Nocturnal concentrations of fine nitrate were, in fact, on average 5 times higher at the rural site than in Bologna. The water uptake by this highly hygroscopic compound under high RH conditions provided the medium for increased nocturnal aerosol uptake of water-soluble organic gases and possibly also for aqueous chemistry, as revealed by the shifting of peak concentrations of secondary compounds (water-soluble organic carbon (WSOC) and sulfate) toward the large accumulation mode (0.42–1.2 µm). Contrarily, the diurnal production of WSOC (proxy for secondary organic aerosol) by photochemistry was similar at the two sites but mostly affected the small accumulation mode of particles (0.14–0.42 µm) in Bologna, while a shift to larger accumulation mode was observed at the rural site. A significant increment in carbonaceous aerosol concentration (for both WSOC and water-insoluble carbon) at the urban site was recorded mainly in the quasi-ultrafine fraction (size range 0.05–0.14 µm), indicating a direct influence of traffic emissions on the mass concentrations of this range of particles.

Measurements of aerosol size distribution and different gas and meteorological parameters, made in three polluted sites in Central and Southern Europe: Po Valley, Italy, Melpitz and Hohenpeissenberg in Germany, were analysed for this study to examine which of the meteorological and trace gas variables affect the number concentration of Aitken (Dp= 50 nm) particles. The aim of our study was to predict the number concentration of 50 nm particles by a combination of in-situ meteorological and gas phase parameters. The statistical model needs to describe, amongst others, the factors affecting the growth of newly formed aerosol particles (below 10 nm) to 50 nm size, but also sources of direct particle emissions in that size range. As the analysis method we used multivariate nonlinear mixed effects model. Hourly averages of gas and meteorological parameters measured at the stations were used as predictor variables; the best predictive model was attained with a combination of relative humidity, new particle formation event probability, temperature, condensation sink and concentrations of SO2, NO2 and ozone. The seasonal variation was also taken into account in the mixed model structure. Model simulations with the Global Model of Aerosol Processes (GLOMAP) indicate that the parameterization can be used as a part of a larger atmospheric model to predict the concentration of climatically active particles. As an additional benefit, the introduced model framework is, in theory, applicable for any kind of measured aerosol parameter.

Atmospheric organic aerosols are generally classified as primary and secondary (POA and SOA) according to their formation processes. An actual separation, however, is challenging when the timescales of emission and gas-to-particle formation overlap. The presence of SOA formation in biomass burning plumes leads to scientific questions about whether the oxidized fraction of biomass burning aerosol is rather of secondary or primary origin, as some studies would suggest, and about the chemical compositions of oxidized biomass burning POA and SOA. In this study, we apply nuclear magnetic resonance (NMR) spectroscopy to investigate the functional group composition of fresh and aged biomass burning aerosols during an intensive field campaign in the Po Valley, Italy. The campaign was part of the EUCAARI project and was held at the rural station of San Pietro Capofiume in spring 2008. Factor analysis applied to the set of NMR spectra was used to apportion the wood burning contribution and other organic carbon (OC) source contributions, including aliphatic amines. Our NMR results, referred to the polar, water-soluble fraction of OC, show that fresh wood burning particles are composed of polyols and aromatic compounds, with a sharp resemblance to wood burning POA produced in wood stoves, while aged samples are clearly depleted of alcohols and are enriched in aliphatic acids with a smaller contribution of aromatic compounds. The comparison with biomass burning organic aerosols (BBOA) determined by high-resolution aerosol mass spectrometry (HR-TOF-AMS) at the site shows only a partial overlap between NMR BB-POA and AMS BBOA, which can be explained by either the inability of BBOA to capture all BB-POA composition, especially the alcohol fraction, or the fact that BBOA account for insoluble organic compounds unmeasured by the NMR. Therefore, an unambiguous composition for biomass burning POA could not be derived from this study, with NMR analysis indicating a higher O/C ratio compared to that measured for AMS BBOA. The comparison between the two techniques substantially improves when adding factors tracing possible contributions from biomass burning SOA, showing that the operational definitions of biomass burning organic aerosols are more consistent between techniques when including more factors tracing chemical classes over a range of oxidation levels. Overall, the non-fossil total carbon fraction was 50-57%, depending on the assumptions about the 14C content of non-fossil carbon, and the fraction of organic carbon estimated to be oxidized organic aerosol (OOA) from HR-TOF-AMS measurements was 73-100% modern

An outline is presented here of the Po Valley Fog Experiment 1989, carried out within the EUROTRAC-GCE project. This experiment is a joint effort by several European research groups from 5 countries. The physical and chemical behaviour of the fog multiphase system was studied experimentally following the temporal evolution of the relevant chemical species in the different phases (gas, droplet, interstitial aerosol) and the evolution of micrometeorological and microphysical conditions, from the pre-fog situation through the whole fog evolution, to the post-fog period. Some general results, useful for describing the general features of the fog system, are presented here, while specific scientific questions on the different processes taking place within the system itself will be addressed in other companion papers of this same issue.DOI: 10.1034/j.1600-0889.1992.t01-4-00002.x