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Identifying the particulate matter (PM) sources is an essential step to assess PM effects on human health and understand PM's behavior in a specific environment. Information about the composition of the organic or/and inorganic fraction of PM is usually used for source apportionment studies. In this study that took place in Dakar, Senegal, the identification of the sources of two PM fractions was performed by utilizing data on the elemental composition and elemental carbon content. Four PM sources were identified using positive matrix factorization (PMF): Industrial emissions, mineral dust, traffic emissions, and sea salt/secondary sulfates. To assess the effect of PM on human health the air quality index (AQI) was estimated. The highest values of AQI are approximately 497 and 488, in Yoff and Hlm, respectively. The spatial location of the sources was investigated using potential source contribution function (PSCF). PSCF plots revealed the high effect of transported dust from the desert regions to PM concentration in the sampling site. To the best of our knowledge, this is the first source apportionment study on PM fractions published for Dakar, Senegal. [ABSTRACT FROM AUTHOR]

Well-type high-purity germanium detectors are well suited for the analysis of small samples, as they combine high detection efficiency with low background radiation. The well geometry however makes efficiency calibration more difficult than that of ordinary HPGe detectors, due to intense true coincidence and possibly random summing effects. Such a detector has been installed at the Environmental Radioactivity Laboratory of the National Centre for Scientific Research "Demokritos". For the calibration of this detector, experimental and Monte Carlo simulation techniques were applied. To this end, calibration sources were produced from the radionuclides available at the Environmental Radioactivity Laboratory. Starting from the geometrical characteristics of the detector as provided by the manufacturer, using the calibration sources and applying Monte Carlo simulation techniques, the detector was characterized and peak efficiency, as well as total-to-peak calibration curves were produced. The results of the calibration finally obtained by simulation are found to be in good agreement with the respective experimental calibration results. [ABSTRACT FROM AUTHOR]

A rare event of mixed biomass-burning and polluted dust aerosols was observed over Athens, Greece (37.9° N, 23.6° E), during 21–26 May 2014. This event was studied using a synergy of a 6-wavelength elastic-Raman-depolarization lidar measurements, a CIMEL sun photometer, and in situ instrumentation. The FLEXPART dispersion model was used to identify the aerosol sources and quantify the contribution of dust and black carbon particles to the mass concentration. The identified air masses were found to originate from Kazakhstan and Saharan deserts, under a rare atmospheric pressure system. The lidar ratio (LR) values retrieved from the Raman lidar ranged within 25–89 sr (355 nm) and 35–70 sr (532 nm). The particle linear depolarization ratio (δaer) ranged from 7 to 28% (532 nm), indicating mixing of dust with biomass-burning particles. The aerosol optical depth (AOD) values derived from the lidar ranged from 0.09–0.43 (355 nm) to 0.07–0.25 (532 nm). An inversion algorithm was used to derive the mean aerosol microphysical properties (mean effective radius (reff), single scattering albedo (SSA), and mean complex refractive index (m)) inside selected atmospheric layers. We found that reff was 0.12–0.51 (±0.04) µm, SSA was 0.94–0.98 (±0.19) (at 532 nm), while m ranged between 1.39 (±0.05) + 0.002 (±0.001)i and 1.63 (±0.05) + 0.008 (±0.004)i. The polarization lidar photometer networking (POLIPHON) algorithm was used to estimate the vertical profile of the mass concentration for the dust and non-dust components. A mean mass concentration of 15 ± 5 μg m−3 and 80 ± 29 μg m−3 for smoke and dust was estimated for selected days, respectively. Finally, the retrieved aerosol microphysical properties were compared with column-integrated sun photometer CIMEL data with good agreement. [ABSTRACT FROM AUTHOR]

The atmospheric concentrations of seventeen elements were measured in air filters at the Finnish Meteorological Institute station in Helsinki, Finland, during a period of 44 years (1962–2005). The mean annual concentrations were calculated and are presented from the lowest values to the highest ones Cr < Ni < Ti < Br < V < Mn < Cu < Zn < Cl < Al < Fe < K < Ca < Na < Pb < Si < S. Most of the elements (Fe, Si, Ti, K, Ca, Zn, Br, Pb, V, Ni, S, Cr, Na, Al, and Cl) present higher values during spring and winter season, while in summer the elements (Ti, Ca, S, and Na) are found in higher concentrationsdue to the weather conditions across seasons and the sources and emissions of air pollutants. There is a strong correlation between the elements (V-Ni, Si-Pb, Fe-Ca, V-Cr, Si-K, K-Ca, Fe-Ti, K-Na, Si-Ca, and V-S), indicating their common source. The identification of the sources of trace elements was performed based on positive matrix factorization analysis, using SoFi software. Four Suspended Particulate Matter (PM) sources were identified: road dust (due to usage of leaded fuel), heavy oil combustion/secondary sulfates, traffic emissions, and natural dust (soil). For the total of 44 years studied, significant decreases in concentrations were observed for all elements, most of which were over 50%: Na (−74%), Al (−86%), Si (−88%), S (−82%), K (−82%), Ca (−89%), Ti (−80%), V (−89%), Cr (−82%), Mn (−77%), Fe (−77%), Ni (−61%), Zn (−72%), and Pb (−95%). In general, a significant decline has been observed in the majority of the elemental concentrations since the end of the 1970s, underlying the effectiveness of different environmental policies that have been applied during the last few decades. [ABSTRACT FROM AUTHOR]

A new gas inlet port combined with a novel ionization scheme have been developed and coupled to a high-resolution time-of-flight mass spectrometer (TOF MS) for the detection and measurement of atmospheric volatile (VOCs) and intermediate volatility organic compounds (IVOCs). Ions are produced predominantly by charge transfer reactions in a low-temperature plasma ionization source with minimal fragmentation. Enhanced sensitivity is accomplished by incorporating an increased-size inlet capillary in a transverse arrangement to maximize throughput in the ionization source. Additional design aspects of the new mass spectrometer enabling superior transmission include a large acceptance ion funnel and a segmented radio frequency (RF) ion guide with increased space charge storage capacity. An orthogonal TOF analyzer equipped with a two-stage reflectron and tuned to second order is employed for the determination of the mass-to-charge ratio of the ions, with a mass resolving power of >20 k at mass 500 Th. The performance of the instrument was evaluated in tests using VOC standards and in atmospheric chamber experiments to demonstrate the ability to measure a wide range of organic compounds with different functional groups. Linear signal response is demonstrated over a wide range of VOCs used in the calibration processes in the ppb range, while the instrument exhibits linear response in the ppt range as well. Detection limits as low as 1 ppt are accomplished. The potential applications of this new TOF MS instrument were demonstrated in a pilot atmospheric simulation chamber experiment. [ABSTRACT FROM AUTHOR]

The current improvements in aerosol mass spectrometers in resolution and sensitivity, and the analytical tools for mass spectra deconvolution, have enabled the in-depth analysis of ambient organic aerosol (OA) properties. Although OA constitutes a major fraction of ambient aerosol, its properties are determined to a great extent by the mixing characteristics of both organic and inorganic components of ambient aerosol. This work applies a new methodology to a year-long ACSM dataset to assess the sources of organic and total non-refractory species in the Athens background aerosol and provides insights into the interactions between organic and inorganic species. The use of innovative tools for applying positive matrix factorization (PMF, rolling window) enables the study of the temporal variability of the contribution of these sources and seasonal changes in their composition. The mass spectra of both organic and inorganic aerosol were obtained by a time-of-flight aerosol mass spectrometer (ToF-ACSM) for PMF analysis. The results revealed five factors when organic aerosol was analysed separately. Three of them were primary OA factors: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA) and biomass burning organic aerosol (BBOA). The remaining two were secondary, less and more oxidized oxygenated organic aerosol (LO-OOA and MO-OOA respectively). The relative contributions of these factors were HOA 15 %, COA 18 %, BBOA 9 %, MO-OOA 34 % and LO-OOA 24 % (yearly averaged). When a combined organic and inorganic aerosol matrix was analysed, two additional factors were identified that were mainly composed of ammonium sulfate (83.5 %) and ammonium nitrate (73 %). Moreover, two secondary factors were resolved, containing both organics and inorganics and were named more (MOA) and less oxidized aerosol (LOA). The relative contributions on a yearly average of these factors were HOA 7 %, COA 9 %, BBOA 3 %, ammonium nitrate 3 %, ammonium sulfate 28 %, MOA 24 % and LOA 26 %. [ABSTRACT FROM AUTHOR]

Although many studies have discussed the impact of Europe's air quality, very limited research focused on the detailed phenomenology of ambient trace elements (TEs) in PM 10 in urban atmosphere. This study compiled long-term (2013–2022) measurements of speciation of ambient urban PM 10 from 55 sites of 7 countries (Switzerland, Spain, France, Greece, Italy, Portugal, UK), aiming to elucidate the phenomenology of 20 TEs in PM 10 in urban Europe. The monitoring sites comprised urban background (UB, n = 26), traffic (TR, n = 10), industrial (IN, n = 5), suburban background (SUB, n = 7), and rural background (RB, n = 7) types. The sampling campaigns were conducted using standardized protocols to ensure data comparability. In each country, PM 10 samples were collected over a fixed period using high-volume air samplers. The analysis encompassed the spatio-temporal distribution of TEs, and relationships between TEs at each site. Results indicated an annual average for the sum of 20 TEs of 90 ± 65 ng/m3, with TR and IN sites exhibiting the highest concentrations (130 ± 66 and 131 ± 80 ng/m3, respectively). Seasonal variability in TEs concentrations, influenced by emission sources and meteorology, revealed significant differences (p < 0.05) across all monitoring sites. Estimation of TE concentrations highlighted distinct ratios between non-carcinogenic and carcinogenic metals, with Zn (40 ± 49 ng/m3), Ti (21 ± 29 ng/m3), and Cu (23 ± 35 ng/m3) dominating non-carcinogenic TEs, while Cr (5 ± 7 ng/m3), and Ni (2 ± 6 ng/m3) were prominent among carcinogenic ones. Correlations between TEs across diverse locations and seasons varied, in agreement with differences in emission sources and meteorological conditions. This study provides valuable insights into TEs in pan-European urban atmosphere, contributing to a comprehensive dataset for future environmental protection policies. • Analysis of 20 trace elements (TEs) in PM 10 across various environments in Europe. • Decade-long, 55-site dataset enhances understanding of TEs dynamics. • TEs concentrations vary significantly between different monitoring sites. • Dominance of Zn, Ti, and Cu indicates diverse pollution sources. • Stricter emission controls and targeted health assessments for urban air quality. [ABSTRACT FROM AUTHOR]

In this study we present the role of the Planetary Boundary Layer Height (PBLH) on the air pollutant concentrations measured at an urban background station at the megacity of Athens, Greece, an area characterized by complex topography. For this purpose, we utilized in situ measurements of aerosol number concentrations at different size bins (10–200 nm) N 10-200nm , (200–550 nm) N 200-550nm , equivalent Black Carbon (eBC), and wind speed data, for the period of May – July 2020. According to our analysis, both horizontal transport and vertical mixing and dispersion of air pollutants play a critical role in air quality. More precisely, PBLH is negatively correlated with aerosol concentration. The increase in the height of the Planetary Boundary Layer (PBL) favors a reduction in aerosol concentration, which, to some extent, compensates for the increase in aerosol load due to emission sources and horizontal transport from the city center. The horizontal advection process is related to the PBLH, since a deep PBL drives the advection, while a shallow PBL is characterized by weak horizontal wind velocities. On the other hand, under stagnant air mass conditions, when the PBL shrinks, the concentrations of air pollutants increase. On average, a 25% increase in the PBLH results in a 15% reduction in aerosol concentration, whereas a 15% reduction in the PBLH may result in a 10% increase in aerosol concentrations. Overall, N 10-200nm particle concentrations increases, when air masses arrive from the S-NW sector (city center) due to traffic and vehicle emissions, while transport of continental pollution mixed with local and regional emissions along the Balkans-Aegean Sea axis, is originating from the NE axis under high wind speeds. The latter is more clearly recognized from aged aerosol components such as sulphate. Whereas, the N 200-550nm and eBC showed increased concentration load under stagnant air mass conditions, independently of the wind direction. [Display omitted] • Horizontal transport, vertical mixing and dispersion of air pollutants play a critical role in air quality. • PBLH is negatively correlated with aerosol concentration. • The increase in the height of the PBL favors a reduction in aerosol concentration, • Under stagnant air mass conditions, when the PBL shrinks, the concentrations of air pollutants increase. [ABSTRACT FROM AUTHOR]

Industrial activities nearby residential areas lead to poor local air quality. Therefore, short-term exposure to an aggravated environment and the subsequent health effects should be the subject of further research. The purpose of this study is to estimate the health risks resulting from such exposure in population groups living in an industrialized area. The risk estimation was performed using different approaches suggested in relative literature. Monitoring of the air quality in an industrial zone of Attica was carried out including 24-h measurements of PM2.5 and analysis of their chemical composition for Polycyclic Aromatic Hydrocarbons and heavy metals (Pb, Cd, As, Ni, Hg, Cu, Zn). Samples of Volatile Organic Compounds were also collected. Health effects on different population subgroups were estimated for the targeted pollutants through different mathematical approaches provided by the literature, taking into consideration different parameters (e.g., age, gender, exposure duration). Inhalation rate and body weight were important parameters to estimate the exposure dose of people, and they can vary greatly depending on the age, gender, and daily activity of the person under consideration. The results indicated that the risk for potential carcinogenic and non-carcinogenic effects varies depending on the applied methodology. In any case, the acceptable limits for cancer risk provided by the OEHHA, EPA, and WHO were not exceeded. [ABSTRACT FROM AUTHOR]

This study analyzed 16070 daily and 608 weekly air filter samples from the Helsinki metropolitan area collected between 1962 and 2005. The aim was to use the Potential Source Contribution Function (PSCF) to determine potential sources of silicon (Si), zinc (Zn), lead (Pb), and radioactive isotope 210Pb. The main sources for Si and Pb were industrial activities, particularly mining, metal industry, and traffic. Common source areas for Zn and 210Pb were identified in the eastern and southeastern parts of the measuring site. • The impact of trace elements on human health. • Time series of forty-four years of elemental concentrations in Finnish air, measured and analyzed by XRF technique. • Decline of Pb concentrations, up to 95%, after the apply of European regulations. • Windblown soil particles, traffic and industrial activities are the main sources of trace elements. [ABSTRACT FROM AUTHOR]

• Studying MAC variability impact on eBC estimation. • Presenting spatial, seasonal and temporal MAC variability in Europe. • Proposing the site-specific MAC as the most effective approach to estimate eBC. • Long-term trend analysis links decreasing EC trends with method-dependent corrected eBC trends. A reliable determination of equivalent black carbon (eBC) mass concentrations derived from filter absorption photometers (FAPs) measurements depends on the appropriate quantification of the mass absorption cross-section (MAC) for converting the absorption coefficient (b abs) to eBC. This study investigates the spatial–temporal variability of the MAC obtained from simultaneous elemental carbon (EC) and b abs measurements performed at 22 sites. We compared different methodologies for retrieving eBC integrating different options for calculating MAC including: locally derived, median value calculated from 22 sites, and site-specific rolling MAC. The eBC concentrations that underwent correction using these methods were identified as LeBC (local MAC), MeBC (median MAC), and ReBC (Rolling MAC) respectively. Pronounced differences (up to more than 50 %) were observed between eBC as directly provided by FAPs (NeBC ; Nominal instrumental MAC) and ReBC due to the differences observed between the experimental and nominal MAC values. The median MAC was 7.8 ± 3.4 m2 g-1 from 12 aethalometers at 880 nm, and 10.6 ± 4.7 m2 g-1 from 10 MAAPs at 637 nm. The experimental MAC showed significant site and seasonal dependencies, with heterogeneous patterns between summer and winter in different regions. In addition, long-term trend analysis revealed statistically significant (s.s.) decreasing trends in EC. Interestingly, we showed that the corresponding corrected eBC trends are not independent of the way eBC is calculated due to the variability of MAC. NeBC and EC decreasing trends were consistent at sites with no significant trend in experimental MAC. Conversely, where MAC showed s.s. trend, the NeBC and EC trends were not consistent while ReBC concentration followed the same pattern as EC. These results underscore the importance of accounting for MAC variations when deriving eBC measurements from FAPs and emphasize the necessity of incorporating EC observations to constrain the uncertainty associated with eBC. [ABSTRACT FROM AUTHOR]

Long-term measurements of carbon in HUmic-LIke Substances (HULIS-C) of ambient size-segregated water soluble organic aerosols were performed using a ten-stage low-pressure Berner impactor from December 2014 to November 2015 at an urban background environment in Ljubljana, Slovenia. The mass size distribution patterns of measured species (PM - particulate matter, WSOC - water-soluble organic carbon and HULIS-C) for all seasons were generally tri-modal (primarily accumulation mode) but with significant seasonal variability. HULIS-C was found to have similar distributions as WSOC, with nearly the same mass median aerodynamic diameters (MMADs), except for winter when the HULIS-C size distribution was bimodal. In autumn and winter, the dominant accumulation mode with MMAD at ca. 0.65 μm contributed 83 and 97% to the total HULIS-C concentration, respectively. HULIS-C accounted for a large fraction of WSOC, averaging more than 50% in autumn and 40% in winter. Alternatively, during warmer periods the contributions of ultrafine (27% in summer) and coarse mode (27% in spring) were also substantial. Based on mass size distribution characteristics, HULIS-C was found to be of various sources. In colder seasons, wood burning was confirmed as the most important HULIS source; secondary formation in atmospheric liquid water also contributed significantly, as revealed by the MMADs of the accumulation mode shifting to larger sizes. The distinct difference between the spring and summer ratios of HULIS-C/WSOC in fine particles (ca. 50% in spring, but only 10% in summer) indicated different sources and chemical composition of WSOC in summer (e.g., SOA formation from biogenic volatile organic compounds (BVOCs) via photochemistry). The enlarged amount of HULIS-C in the ultrafine mode in summer suggests that the important contribution was most likely from new particle formation during higher emissions of BVOC due to the vicinity of a mixed deciduous forest; the higher contribution of HULIS-C in the coarse mode demonstrated that beside soil erosion other sources, such as pollen and plant fragments, could also be responsible. [ABSTRACT FROM AUTHOR]

Atmospheric particulate matter (PM 2.5 ) samples were collected over two one month periods during winter and summer in three Southern European cities (Oporto – traffic site, Florence – urban background, Athens - suburban). Concentrations of 27 polycyclic aromatic hydrocarbons (PAHs), 15 nitro-PAHs (NPAHs), 15 oxygenated-PAHs (OPAHs) and 4 azaarenes (AZAs) were determined. On average, the winter-summer concentrations of ΣPAHs were 16.3–5.60, 7.75–3.02 and 3.44–0.658 ng m − 3 in Oporto, Florence and Athens, respectively. The corresponding concentrations of ΣNPAHs were 15.8–9.15, 10.9–3.36 and 15.9–2.73 ng m − 3 , whilst ΣOPAHs varied in the ranges 41.8–19.0, 11.3–3.10 and 12.6–0.704 ng m − 3 . Concentrations of ΣAZAs were always below 0.5 ng m − 3 . Irrespective of the city, the dominant PAHs were benzo[b + j + k]fluoranthene, retene, benzo[ ghi ]perylene and indeno[1,2,3- cd ]pyrene. The most abundant OPAH in all cities was 1,8-naphthalic anhydride, whereas 5-nitroacenaphthene was the prevailing NPAH. The ΣOPAHs/ΣPAHs and ΣNPAHs/ΣPAHs were higher in summer than in winter, suggesting increasing formation of derivatives by photochemical degradation of PAHs. Molecular diagnostic ratios suggested that, after traffic, biomass burning was the dominant emission source. Apart from being influenced by seasonal sources, the marked differences between winter and summer may indicate that these diagnostic ratios are particularly sensitive to photodegradation, and thus should be applied and interpreted cautiously. The lifetime excess cancer risk from inhalation was, in part, attributable to PAH derivatives, acclaiming the need to include these compounds in regular monitoring programmes. On average, 206, 88 and 26 cancer cases per million people were estimated, by the World Health Organisation method, for the traffic-impacted, urban background and suburban atmospheres of Oporto, Florence and Athens, respectively. [ABSTRACT FROM AUTHOR]

Elemental characterization of air particulate matter samples through the application of X-ray fluorescence (XRF) spectrometry is a widespread analytical technique. This work presents the optimization and calibration methodology of a handheld XRF spectrometer and its subsequent application in elemental quantification of unknown particulate matter samples. The optimization of the handheld spectrometer was conducted through investigation of the elemental sensitivities and Limits of Detection (LoD) at variable excitation conditions (voltage, filter). Accordingly, five optimum operating conditions were obtained each one targeted in different elemental range: 1) Z = 11–12, 2) 12 < Z < 17, 3) 16 < Z < 23, 4) 22 < Z < 31 and 5) 30 < Z < 92. Subsequently, a number of reference (5 multi-element and 42 compound/single-element) materials were used to obtain calibration curves for 24 elements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Pb). Weighted least-square regression analysis was implemented to best fit the experimentally measured intensities with mass loadings resulting for most of the elements to high correlations (Pearson r > 0.98) and low statistical error. In addition, intercomparison of the elemental concentrations from 28 unknown particulate matter samples between the handheld and a benchtop XRF spectrometer showed good agreement. [Display omitted] • A commercial handheld XRF spectrometer was investigated for analysis of PM samples. • Response of the HHXRF revealed limitations arising from instrument blank contributions. • Optimization resulted in 5 operating conditions targeted to different elemental range. • Elemental concentrations were successfully measured by the handheld XRF spectrometer. • Handheld/benchtop inter-comparison showed good agreement and generally comparable limits of detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Source apportionment of organic aerosol in 22 year-long datasets in Europe; • Harmonised source apportionment protocol; • Oxygenated organic aerosol dominates across Europe in all seasons; • Solid-fuel combustion is a significant source in most European sites, especially in winter; • Traffic source is present in both urban and non-urban sites with constant and non-negligible contributions. Organic aerosol (OA) is a key component of total submicron particulate matter (PM 1), and comprehensive knowledge of OA sources across Europe is crucial to mitigate PM 1 levels. Europe has a well-established air quality research infrastructure from which yearlong datasets using 21 aerosol chemical speciation monitors (ACSMs) and 1 aerosol mass spectrometer (AMS) were gathered during 2013–2019. It includes 9 non-urban and 13 urban sites. This study developed a state-of-the-art source apportionment protocol to analyse long-term OA mass spectrum data by applying the most advanced source apportionment strategies (i.e., rolling PMF, ME-2, and bootstrap). This harmonised protocol was followed strictly for all 22 datasets, making the source apportionment results more comparable. In addition, it enables quantification of the most common OA components such as hydrocarbon-like OA (HOA), biomass burning OA (BBOA), cooking-like OA (COA), more oxidised-oxygenated OA (MO-OOA), and less oxidised-oxygenated OA (LO-OOA). Other components such as coal combustion OA (CCOA), solid fuel OA (SFOA: mainly mixture of coal and peat combustion), cigarette smoke OA (CSOA), sea salt (mostly inorganic but part of the OA mass spectrum), coffee OA, and ship industry OA could also be separated at a few specific sites. Oxygenated OA (OOA) components make up most of the submicron OA mass (average = 71.1%, range from 43.7 to 100%). Solid fuel combustion-related OA components (i.e., BBOA, CCOA, and SFOA) are still considerable with in total 16.0% yearly contribution to the OA, yet mainly during winter months (21.4%). Overall, this comprehensive protocol works effectively across all sites governed by different sources and generates robust and consistent source apportionment results. Our work presents a comprehensive overview of OA sources in Europe with a unique combination of high time resolution (30–240 min) and long-term data coverage (9–36 months), providing essential information to improve/validate air quality, health impact, and climate models. [ABSTRACT FROM AUTHOR]

Atmospheric new particle formation (NPF) is a naturally occurring phenomenon, during which high concentrations of sub-10 nm particles are created through gas to particle conversion. The NPF is observed in multiple environments around the world. Although it has observable influence onto annual total and ultrafine particle number concentrations (PNC and UFP, respectively), only limited epidemiological studies have investigated whether these particles are associated with adverse health effects. One plausible reason for this limitation may be related to the absence of NPF identifiers available in UFP and PNC data sets. Until recently, the regional NPF events were usually identified manually from particle number size distribution contour plots. Identification of NPF across multi-annual and multiple station data sets remained a tedious task. In this work, we introduce a regional NPF identifier, created using an automated, machine learning based algorithm. The regional NPF event tag was created for 65 measurement sites globally, covering the period from 1996 to 2023. The discussed data set can be used in future studies related to regional NPF., Competing Interests: Competing interests The authors declare no competing interests. The views expressed are those of the author(s) and not necessarily those of the NIHR, UKHSA or the Department of Health and Social Care., (© 2024. The Author(s).)

Background: Guidelines recommend enteral feeding via gastrostomy should be considered for adult survivors of stroke with dysphagia who cannot eat or drink sufficiently for >4 weeks. Many people continue long-term tube-feeding via this route in the community where healthcare professionals contribute to their care and nutritional management, although little is known about their experiences of or attitudes towards enteral feeding in this situation. The present study aimed to explore the experiences and attitudes of healthcare professionals working with this patient group., Methods: Healthcare professionals were invited to complete a questionnaire devised for the study which comprised closed and open questions about tube-feeding including their patients' participation in feeding processes and mealtimes and how these might be improved. Responses to closed questions were analysed descriptively and free-text responses analysed using thematic analysis., Results: Fifty-seven participants met the inclusion criteria. They identified patients' quality of life (77% of respondents) and nutritional support (75%) as the most important aspects of tube-feeding. Good communication and training with healthcare teams and carers were considered important. Their patients' participation in tube-feed administration and mealtime involvement were described as variable and potentially beneficial, but both were related to patients' choice and health impairment. Blended tube-feeding was considered an option by 89% provided practical and safety conditions were met., Conclusions: Participants' experiences of and attitudes towards tube feeding in adults living with stroke in the community in the sample in the present study are varied and focussed on individual patients' needs, safety and professional standards., (© 2024 The Author(s). Journal of Human Nutrition and Dietetics published by John Wiley & Sons Ltd on behalf of British Dietetic Association.)

This work presents the first comprehensive assessment of PM pollution sources in Dushanbe, Tajikistan. A total of 138 PM 2.5 samples were collected during 2015-2016 and 2018-2019 and were analyzed through gravimetric, ED-XRF, and multi-wavelength absorption techniques. The results show that PM 2.5 concentrations were substantially higher than the European annual limit value and WHO Air Quality Guidelines annual average value, with an average of 90.9 ± 68.5 μg m -3 . The PMF application identified eight sources of pollution that influenced PM 2.5 concentration levels in the area. Coal burning (21.3%) and biomass burning (22.3%) were the dominant sources during the winter, while vehicular traffic (7.7%) contributed more during the warm season. Power plant emissions (17.5%) showed enhanced contributions during the warm months, likely due to high energy demand. Cement industry emissions (6.9%) exhibited significant contribution during the cold period of 2018-2019, while soil dust (11.3%) and secondary sulphates (11.5%) displayed increased contribution during the warm and cold months, respectively. Finally, waste burning (1.5%) displayed the lowest contribution, with no significant temporal variation. Our results highlight the significant impact of anthropogenic activities, and especially the use of coal burning for energy production (both in power plants and for residential heating), and the significant contribution of biomass burning during both warm and cold seasons., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Poor air quality in workplaces constitutes a great concern on human health as a good fraction of our time is spent at work. In Greece, very unique workplaces are the street corner kiosks, which are freestanding boxes placed on sidewalks next to city streets and vehicular traffic, where one can find many consumer goods. As such, its employees are exposed to both outdoor and indoor air pollutants. Very few studies have examined the occupational exposure of kiosk workers to air pollutants, and thus the magnitude of this unique indoor and outdoor exposure remains unknown. The objective of this study is to investigate and compare the levels of indoor and outdoor particulate matter (PM 10 and PM 2.5 ), ultrafine particles (UFPs) and black carbon (BC) in different kiosks located in Athens, Greece, in urban-traffic and urban-background environments. Continuous measurements of the above-mentioned pollutants were carried out on a 24-h basis over 7 consecutive days at three kiosks from September to October 2019. Indoor PM 10 concentrations in the urban kiosk ranged from 19.0 to 44.0 μg/m 3 , PM 2.5 values ranged from 14.0 to 33.0 μg/m 3 , whereas BC concentrations ranged from 1.2 to 7.0 μg/m 3 and UFPs from almost 9.5 to 47.0 × 10 3  pt/cm 3 . Outdoor PM 10 and PM 2.5 measurements ranged from 29.0 to 59.0 μg/m 3 and from 22.0 to 39.0 μg/m 3 , respectively. BC outdoor concentrations ranged from 1.1 to 2.2 μg/m 3 . The mean hazard quotient (HQ) for PM 10 (4.9) and PM 2.5 (4.7) among all participants was >1. The health risk of exposure to PM 10 and PM 2.5 was found to be at moderate hazard levels, although in some cases we observed HQ values higher than 10 due to high PM 10 and PM 2.5 concentrations in the kiosks. Overall our study indicates that people working at kiosks can be exposed to very high concentrations on particulate pollution depending on a number of factors including the traffic that strongly depends on location and the time of the day., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Olga-Ioanna Kalantzi was an Associate Editor of Heliyon Environment until March 2024., (© 2024 The Authors.)

Ultrafine particles (UFP, those with diameters ≤ 100 nm), have been reported to potentially penetrate deeply into the respiratory system, translocate through the alveoli, and affect various organs, potentially correlating with increased mortality. The aim of this study is to assess long-term trends (5-11 years) in mostly urban UFP concentrations based on measurements of particle number size distributions (PNSD). Additionally, concentrations of other pollutants and meteorological variables were evaluated to support the interpretations. PNSD datasets from 12 urban background (UB), 5 traffic (TR), 3 suburban background (SUB) and 1 regional background (RB) sites in 15 European cities and 1 in the USA were evaluated. The non-parametric Theil-Sen's method was used to detect monotonic trends. Meta-analyses were carried out to assess the overall trends and those for different environments. The results showed significant decreases in NO, NO 2 , BC, CO, and particle concentrations in the Aitken (25-100 nm) and the Accumulation (100-800 nm) modes, suggesting a positive impact of the implementation of EURO 5/V and 6/VI vehicle standards on European air quality. The growing use of Diesel Particle Filters (DPFs) might also have clearly reduced exhaust emissions of BC, PM, and the Aitken and Accumulation mode particles. However, as reported by prior studies, there remains an issue of poor control of Nucleation mode particles (smaller than 25 nm), which are not fully reduced with current DPFs, without emission controls for semi-volatile organic compounds, and might have different origins than road traffic. Thus, contrasting trends for Nucleation mode particles were obtained across the cities studied. This mode also affected the UFP and total PNC trends because of the high proportion of Nucleation mode particles in both concentration ranges. It was also found that the urban temperature increasing trends might have also influenced those of PNC, Nucleation and Aitken modes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Carbapenems are considered to be among the last line antibiotics against extended-spectrum β-lactamase producing Enterobacterales. Carbapenem-resistant Klebsiella pneumoniae (CRKP) has been frequently reported and its spread in Europe is indisputable and poses an enormous threat to hospitalized patients which is of growing concern. This review aims to record prevalence of CRKP in the Balkan region and to review the current knowledge about this life-threatening pathogen. In this review, we summarize data about clinical isolates of carbapenem-resistant K. pneumoniae from Greece, Croatia, Romania, Bulgaria, Serbia, Slovenia, Montenegro, Bosnia-Herzegovina and Albania from published reports between 2000 and 2023. Among Balkan countries, Greece and Romania are the ones with the most reports about CRKP. Since 2007, KPCs are the dominant carbapenemases in both countries. KPC-2 and NDM-1-producing K. pneumoniae strains have been identified as the most frequent CRKP in Croatia, Bulgaria, Serbia, and Slovenia. OXA-48 enzyme has been identified in most Balkan countries. In addition, since 2018, CRKP sequence type 11 (ST11) seems to have replaced ST258 in Balkan Peninsula, while ST15 continues to thrive throughout the years. Not only efficacy of colistin against CRKP has decreased dramatically during the last ten years but colistin resistance mechanism is based on alterations of chromosomal mgrB gene, rather than the already known mcr genes.Moreover, ceftazidime-avibactam-resistant CRKP were detected mostly in Greece. Emergence of CRKP poses a severe threat to the Balkan countries. Due to the narrow therapeutic window, it is essential to prevent the spread of multiresistant K. pneumoniae strains.

Recent years have shown that secondary ice production (SIP) is ubiquitous, affecting all clouds from polar to tropical regions. SIP is not described well in models and may explain biases in warm mixed-phase cloud ice content and structure. Through modeling constrained by in-situ observations and its synergy with radar we show that SIP in orographic clouds exert a profound impact on the vertical distribution of hydrometeors and precipitation, especially in seeder-feeder cloud configurations. The mesoscale model simulations coupled with a radar simulator strongly support that enhanced aggregation and SIP through ice-ice collisions contribute to observed spectral bimodalities, skewing the Doppler spectra toward the slower-falling side at temperatures within the dendritic growth layer, ranging from -20 °C to -10 °C. This unique signature provides an opportunity to infer long-term SIP occurrences from the global cloud radar data archive, particularly for this underexplored temperature regime., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2024.)

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 PN 10-25 , 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 PN 10-25 , 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 PN 25-800 , was positively correlated with BC, NO 2 , 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 size fraction., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In this study, we investigated the impact of urban emission sources on the chemical composition of ambient particulate matter (PM) as well as the associated oxidative potential. We collected six sets of PM samples in five urban location sites around the world over long time periods varying from weeks to months, intentionally selected for their PM to be dominated by unique emission sources: (1) PM 2.5 produced mainly by traffic emissions in central Los Angeles, United States (US); (2) PM 2.5 dominated by biomass burning in Milan, Italy; (3) PM 2.5 formed by secondary photochemical reactions thus dominated by secondary aerosols in Athens, Greece; (4) PM 10 emitted by refinery and dust resuspension in Riyadh, Saudi Arabia (SA); (5) PM 10 generated by dust storms in Riyadh, SA, and (6) PM 2.5 produced mainly by industrial and traffic emissions in Beirut, Lebanon. The PM samples were chemically analyzed and their oxidative potential were quantified by employing the dithiothreitol (DTT) assay. Our results revealed that the Milan samples were rich in water soluble organic carbon (WSOC) and PAHs, even exceeding the levels measured on Los Angeles (LA) freeways. The PM in Athens was characterized by high concentrations of inorganic ions, specifically sulfate which was the highest of all PM samples. The ambient PM in LA was impacted by the traffic-emitted primary organic and elemental carbon. Furthermore, the contribution of metals and elements per mass of PM in Riyadh and Beirut samples were more pronounced relative to other sampling areas. The highest intrinsic PM redox activity was observed for PM with the highest WSOC fraction, including Milan (biomass burning) and Athens (secondary organic aerosols, SOA). PM in areas characterized by high metal emissions including dust events, refinery and industry, such as Riyadh and Beirut, had the lowest oxidative potential as assessed by the DTT assay. The results of this study illustrate the impact of major emission sources in urban areas on the redox activity and oxidative potential of ambient PM, providing useful information for developing efficient air pollution control and mitigation policies in polluted areas around the globe., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Aerosols play an important yet uncertain role in modulating the radiation balance of the sensitive Arctic atmosphere. Organic aerosol is one of the most abundant, yet least understood, fractions of the Arctic aerosol mass. Here we use data from eight observatories that represent the entire Arctic to reveal the annual cycles in anthropogenic and biogenic sources of organic aerosol. We show that during winter, the organic aerosol in the Arctic is dominated by anthropogenic emissions, mainly from Eurasia, which consist of both direct combustion emissions and long-range transported, aged pollution. In summer, the decreasing anthropogenic pollution is replaced by natural emissions. These include marine secondary, biogenic secondary and primary biological emissions, which have the potential to be important to Arctic climate by modifying the cloud condensation nuclei properties and acting as ice-nucleating particles. Their source strength or atmospheric processing is sensitive to nutrient availability, solar radiation, temperature and snow cover. Our results provide a comprehensive understanding of the current pan-Arctic organic aerosol, which can be used to support modelling efforts that aim to quantify the climate impacts of emissions in this sensitive region., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2022.)

Air quality in urban areas and megacities is dependent on emissions, physicochemical process and atmospheric conditions in a complex manner. The impact on air quality metrics of the COVID-19 lockdown measures was evaluated during two periods in Athens, Greece. The first period involved stoppage of educational and recreational activities and the second severe restrictions to all but necessary transport and workplace activities. Fresh traffic emissions and their aerosol products in terms of ultrafine nuclei particles and nitrates showed the most significant reduction especially during the 2nd period (40-50%). Carbonaceous aerosol both from fossil fuel emissions and biomass burning, as well as aging ultrafine and accumulation mode particles showed an increase of 10-20% of average before showing a decline (5 to 30%). It is found that removal of small nuclei and Aitken modes increased growth rates and migration of condensable species to larger particles maintaining aerosol volume., (© 2021. The Author(s).)

The aim of this work is to study the atmospheric concentrations of selected major and trace elements and ions found in PM 2.5 , at a suburban site in Athens, Greece, and discuss on the impact of the different sources. Special focus is given to the influence of Saharan dust episodes. The seasonal variability in the metal and ion concentrations is also examined. The results show that PM 2.5 mass concentrations are significantly influenced by Saharan dust events; it is observed that when the PM 2.5 concentration is higher than 25 μg/m 3 , five out of six times, the air mass crossed North Africa at an altitude within the boundary layer. Fe is found to be the element with the more significant seasonal variability, displaying much higher concentrations during cold period. The frequent Saharan dust intrusions in the cold period of this dataset may explain this result. Mineral dust and secondary aerosol are the main PM 2.5 components (29 and 34%, respectively). During Saharan dust events, the concentration of mineral dust is increased by 35% compared to the days without dust intrusions, while an increase of 68% of the sea salt is also observed. During event days, PM 2.5 concentrations are also increased by 14%. Anthropogenic components do not decrease during those days, while sulfate displays even a slight increase, suggesting enrichment of mineral dust with secondary sulfates. The results indicate that African dust intrusions add a rather significant PM pollution load even in the PM 2.5 fraction, with implication to population exposure and human health.

The objective of this work was to study PM(10) and PM(2.5) concentration data available from monitoring stations in two large urban agglomerations in Greece and to estimate the emissions reduction required for compliance with the EU Air Quality Standards (AQS) for particulate matter. The cities studied are namely the Athens and Thessaloniki Metropolitan Areas (AMA and TMA, respectively). PM(10) concentrations during the period 2001-2010 have been evaluated for 15 air quality monitoring stations in the two urban areas. It was found that the concentrations of PM(10) during the period studied constantly exceeded the threshold values at the traffic and industrial stations in TMA and most of the traffic sites in AMA. Most of the occurrences of non-attainment to the daily AQSs were observed during the winter period at all stations (more pronounced for TMA stations). The reduction in current emission source strength to meet the air quality goal was calculated by the rollback equation using PM(10) day-averaged concentrations over the selected period at each station. Among the lognormal and Weibull distributions, the lognormal distribution was found to best fit the frequency distributions of PM(10) concentrations at the selected stations. The results showed that the minimum reduction required in order to meet the AQS in the AMA ranges from approximately 20 to 38% and up to 11% for traffic and background stations, respectively. Reductions in the range of 31% for traffic and 44% for industrial areas in TMA are also required. The same methodology was applied to PM(2.5) concentrations in the AMA and showed that emission reductions up to 31% are necessary in order to meet the 2020 EU AQS. Finally, continuous concentration data of organic (OC) and elementary carbon (EC) in PM(2.5) were used to study the possibility of achieving specific emission attenuation objectives in AMA.