Annual variation of source contributions to PM10 and oxidative potential in a mountainous area with traffic, biomass burning, cement-plant and biogenic influences.

Toxicity of particulate matter (PM) depends on its sources, size and composition. We identified PM10 sources and determined their contribution to oxidative potential (OP) as a health proxy for PM exposure in an Alpine valley influenced by cement industry. PM10 filter sample chemical analysis and equivalent black carbon (eBC) were measured at an urban background site from November 2020 to November 2021. Using an optimized Positive Matrix Factorization (PMF) model, the source chemical fingerprints and contributions to PM10 were determined. The OP assessed through two assays, ascorbic acid (AA) and dithiothreitol (DTT), was attributed to the PM sources from the PMF model with a multiple linear regression (MLR) model. Ten factors were found at the site, including biomass burning (34, 40 and 38% contribution to annual PM10, OPAA and OPDDT, respectively), traffic (14, 19 and 7%), nitrate- and sulphate-rich (together: 16, 5 and 8%), aged sea salt (2, 2 and 0%) and mineral dust (10, 12 and 17%). The introduction of innovative organic tracers allowed the quantification of the PM primary and secondary biogenic fractions (together: 13, 8 and 21%). In addition, two unusual factors due to local features, a chloride-rich factor and a second mineral dust-rich factor (named the cement dust factor) were found, contributing together 10, 14 and 8%. We associate these two factors to different processes in the cement plant. Despite their rather low contribution to PM10 mass, these sources have one of the highest OPs per µg of source. The results of the study provide vital information about the influence of particular sources on PM10 and OP in complex environments and are thus useful for PM control strategies and actions.

Mass size distributions, composition and dose estimates of particulate matter in Saharan dust outbreaks.

The present study highlights the importance of examining the contribution of Saharan dust (SD) sources not only in terms of overall mass contribution but also in terms of composition, size distribution and inhaled dose. The effect of SD intrusions on PM and the respective major and trace metals mass concentrations and size distributions was investigated in a suburban site in Athens, Greece. SD events were associated, on average, with lower boundary layer heights (BLH) compared to the non-Sahara (nSD) dust days. During SD events, PM1-10 concentrations showed an increasing trend with increasing atmospheric BLH, in contrary to the fine PM (PM1). Generally, increased PM1 and CO (i.e. anthropogenic origin) levels were observed for BLH lower than around 500 m. The average contribution of SD to PM10 and PM2.5 mass concentration was roughly equal to 30.9% and 19.4%, respectively. The mass size distributions of PM and specific major and trace elements (Na, Al, Si, S, Cl, K, Ca, Fe, and Zn) displayed a somewhat different behavior with respect to the mass origin (Algeria-Tunisia vs Libya-Egypt), affecting in turn the regional deposition of inhaled aerosol in the human respiratory tract (HRT). The average PM deposited mass in the upper and lower HRT was 80.1% (Head) and 26.9% (Lung; Tracheobronchial and Pulmonary region) higher for SD days than for nSD days. Higher doses were estimated in the upper and lower HRT for the majority of the elements, when SD intrusions occurred, supporting the increasingly growing interest in exploring the health effects of SD. Only the mass deposition for S, and Na in the lower HRT and Zn in the upper HRT was higher in the case of nSD.

Assessment of children's exposure to carbonaceous matter and to PM major and trace elements.

Particulate matter (PM) pollution is one of the major environmental concerns due to its harmful effects on human health. As children are particularly vulnerable to particle exposure, this study integrates the concentration of PM chemical compounds measured in the micro-environments (MEs) where children spend most of their time to assess the daily exposure and inhaled dose. PM samples were analysed for organic and elemental carbon and for major and trace elements. Results showed that the MEs that contribute most to the children's daily exposure (80%) and inhaled dose (65%) were homes and schools. Results indicated that the high contribution of particulate organic matter (POM) indoors indicate high contributions of indoor sources to the organic fraction of the particles. The highest concentrations of PM chemical compounds and the highest Indoor/Outdoor ratios were measured in schools, where the contribution of mineral elements stands out due to the resuspension of dust caused by the students and to the chalk used in blackboards. The contribution of the outdoor particles to inhaled dose (24%) was higher than to the exposure (12%), due to the highest inhalation rates associated with the activities performed outdoor. This study indicates the importance of indoor air quality for the children's exposure and health.

Multi-city comparative PM2.5 source apportionment for fifteen sites in Europe: The ICARUS project.

PM2.5 is an air pollution metric widely used to assess air quality, with the European Union having set targets for reduction in PM2.5 levels and population exposure. A major challenge for the scientific community is to identify, quantify and characterize the sources of atmospheric particles in the aspect of proposing effective control strategies. In the frame of ICARUS EU2020 project, a comprehensive database including PM2.5 concentration and chemical composition (ions, metals, organic/elemental carbon, Polycyclic Aromatic Hydrocarbons) from three sites (traffic, urban background, rural) of five European cities (Athens, Brno, Ljubljana, Madrid, Thessaloniki) was created. The common and synchronous sampling (two seasons involved) and analysis procedure offered the prospect of a harmonized Positive Matrix Factorization model approach, with the scope of identifying the similarities and differences of PM2.5 key-source chemical fingerprints across the sampling sites. The results indicated that the average contribution of traffic exhausts to PM2.5 concentration was 23.3% (traffic sites), 13.3% (urban background sites) and 8.8% (rural sites). The average contribution of traffic non-exhausts was 12.6% (traffic), 13.5% (urban background) and 6.1% (rural sites). The contribution of fuel oil combustion was 3.8% at traffic, 11.6% at urban background and 18.7% at rural sites. Biomass burning contribution was 22% at traffic sites, 30% at urban background sites and 28% at rural sites. Regarding soil dust, the average contribution was 5% and 8% at traffic and urban background sites respectively and 16% at rural sites. Sea salt contribution was low (1-4%) while secondary aerosols corresponded to the 16-34% of PM2.5. The homogeneity of the chemical profiles as well as their relationship with prevailing meteorological parameters were investigated. The results showed that fuel oil combustion, traffic non-exhausts and soil dust profiles are considered as dissimilar while biomass burning, sea salt and traffic exhaust can be characterized as relatively homogenous among the sites.

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.

Ambient particulate matter source apportionment using receptor modelling in European and Central Asia urban areas.

This work presents the results of a PM2.5 source apportionment study conducted in urban background sites from 16 European and Asian countries. For some Eastern Europe and Central Asia cities this was the first time that quantitative information on pollution source contributions to ambient particulate matter (PM) has been performed. More than 2200 filters were sampled and analyzed by X-Ray Fluorescence (XRF), Particle-Induced X-Ray Emission (PIXE), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to measure the concentrations of chemical elements in fine particles. Samples were also analyzed for the contents of black carbon, elemental carbon, organic carbon, and water-soluble ions. The Positive Matrix Factorization receptor model (EPA PMF 5.0) was used to characterize similarities and heterogeneities in PM2.5 sources and respective contributions in the cities that the number of collected samples exceeded 75. At the end source apportionment was performed in 11 out of the 16 participating cities. Nine major sources were identified to have contributed to PM2.5: biomass burning, secondary sulfates, traffic, fuel oil combustion, industry, coal combustion, soil, salt and "other sources". From the averages of sources contributions, considering 11 cities 16% of PM2.5 was attributed to biomass burning, 15% to secondary sulfates, 13% to traffic, 12% to soil, 8.0% to fuel oil combustion, 5.5% to coal combustion, 1.9% to salt, 0.8% to industry emissions, 5.1% to "other sources" and 23% to unaccounted mass. Characteristic seasonal patterns were identified for each PM2.5 source. Biomass burning in all cities, coal combustion in Krakow/POL, and oil combustion in Belgrade/SRB and Banja Luka/BIH increased in Winter due to the impact of domestic heating, whereas in most cities secondary sulfates reached higher levels in Summer as a consequence of the enhanced photochemical activity. During high pollution days the largest sources of fine particles were biomass burning, traffic and secondary sulfates.

The traffic signature on the vertical PM profile: Environmental and health risks within an urban roadside environment.

In an attempt to investigate the traffic-impacted vertical aerosols profile and its relationship with potential carcinogenicity and/or mutagenicity, samples of different sized airborne particles were collected in parallel at the 1st and 5th floor of a 19 m high building located next to one of the busiest roads of Athens. The maximum daily concentrations were 65.9, 42.5 and 38.5 µg/m3, for PM10, PM2.5 and PM1, respectively. The vertical concentration ratio decreased with increasing height verifying the role of the characteristics of the area (1st/5th floor: 1.21, 1.13, 1.09 for PM10, PM2.5 and PM1, respectively). Chemically, strengthening the previous hypothesis, the collected particles were mainly carbonaceous (68%-93%) with the maximum budget of the polyaromatic hydrocarbons being recorded near the surface (1st/5th floor: 1.84, 1.07, 1.15 for PM10, PM2.5 and PM1, respectively). The detected PM-bound PAHs along with the elements as well as the carbonaceous and ionic constituents were used in a source apportionment study. Exhaust and non-exhaust emissions, a mixed source of biomass burning and high temperature combustion processes (natural gas, gasoline/diesel engines), sea salt, secondary and soil particles were identified as the major contributing sources to the PM pollution of the investigated area. With respect to the health hazards, the calculation of the Benzo[a]Pyrene toxicity equivalency factors underlined the importance of the height of residence in buildings for the level of the exposure (1st/5th floor: B[a]PTEQ: 1.82, 1.12, 1.10, B[a]PMEQ: 1.85, 1.13, 1.09 for PM10, PM2.5 and PM1, respectively). Finally, despite its verified significance as a surrogate compound for the mixture of the hydrocarbons (its contribution up to 72%, 79% on the level of the 1st and 5th floor, respectively), the importance of the incorporation of PAH species in addition to B[a]P when assessing PAH toxicity was clearly documented.

East Siberian Arctic background and black carbon polluted aerosols at HMO Tiksi.

Assessment of Arctic pollution is hampered by a lack of aerosol studies in Northern Siberia. Black carbon observations were carried out at the Hydrometeorological Observatory Tiksi, a coast of Laptev sea, from September 2014 to September 2016. Aerosol sampling was accompanied by physico-chemical characterization. BC climatology showed a seasonal variation with highest concentrations from January to March (up to 450ng/m3) and lowest ones for June and September (about 20ng/m3). Stagnant weather and stable atmosphere stratification resulted in accumulation of pollution, in dependence on the wind direction and air mass transportation. Carbon fractions, functionalities, ions, and elements are associated to marine, biogenic, and continental sources. In September low OC, aliphatic, carbonyls, amines, and hydroxyls characterize background aerosols. Na+/Cl- ratio much higher than in sea-salt indicates a strong Cl depletion. Increased OC, aromatic, carbonyls, and nitrocompounds as well as waste burning markers K+, Cl-, and PO42- confirm impacts from Tiksi landfill burns. BC pollution episodes are differentiated through increased EBC and sulfates, related to gas flaring, industrial and residential emissions transported from Western Siberia while the increase of carbonyls, hydroxyl, and aromatic indicate emissions sources from Yakutia and Tiksi urban area. Arctic Haze aerosols are characterized by increased concentrations of SO42- in comparison with OC, much higher abundance of oxygenated compounds with respect to alkanes of anthropogenic origin. In summer rich organic chemistry indicates impacts of biogenic, local urban, and shipping sources as well as secondary aerosol formation influenced by emissions from low latitude Siberia.

Monitoring of air pollution levels related to Charilaos Trikoupis Bridge.

Charilaos Trikoupis bridge is the longest cable bridge in Europe that connects Western Greece with the rest of the country. In this study, six air pollution monitoring campaigns (including major regulated air pollutants) were carried out from 2013 to 2015 at both sides of the bridge, located in the urban areas of Rio and Antirrio respectively. Pollution data were statistically analyzed and air quality was characterized using US and European air quality indices. From the overall campaign, it was found that air pollution levels were below the respective regulatory thresholds, but once at the site of Antirrio (26.4 and 52.2µg/m3 for PM2.5 and ΡΜ10, respectively) during the 2nd winter period. Daily average PM10 and PM2.5 levels from two monitoring sites were well correlated to gaseous pollutant (CO, NO, NO2, NOx and SO2) levels, meteorological parameters and factor scores from Positive Matrix Factorization during the 3-year period. Moreover, the elemental composition of PM10 and PM2.5 was used for source apportionment. That analysis revealed that major emission sources were sulfates, mineral dust, biomass burning, sea salt, traffic and shipping emissions for PM10 and PM2.5, for both Rio and Antirrio. Seasonal variation indicates that sulfates, mineral dust and traffic emissions increased during the warm season of the year, while biomass burning become the dominant during the cold season. Overall, the contribution of the Charilaos Trikoupis bridge to the vicinity air pollution is very low. This is the result of the relatively low daily traffic volume (~10,000 vehicles per day), the respective traffic fleet composition (~81% of the traffic fleet are private vehicles) and the speed limit (80km/h) which does not favor traffic emissions. In addition, the strong and frequent winds further contribute to the rapid dispersion of the emitted pollutants.

Particulate matter pollution from aviation-related activity at a small airport of the Aegean Sea Insular Region.

The unprecedented growth in aviation during the last years has resulted in a notable increase of local air pollution related to airports. The impacts of aviation on air quality can be extremely high particularly around airports serving remote insular regions with pristine atmospheric environments. Here we report measurements that show how the atmospheric aerosol is affected by the activity at a small airport in a remote region. More specifically, we provide measurements performed at the airport of Mytilene, Greece, a regional yet international airport that serves the entire island of Lesvos; the third largest island of the country. The measurements show that the activity during landing, taxiing and take-off of the aircrafts accounted for up to a 10-fold increase in particulate matter (PM) mass concentration in the vicinity of the airport. The number concentration of particles having diameters from 10 to 500nm also increased from ca. 4×102 to 8×105particlescm-3, while the mean particle diameter decreased to 20nm when aircrafts were present at the airport. Elemental analysis on particle samples collected simultaneously at the airport and at a remote site 3km away, showed that the former were significantly influenced by combustion sources, and specifically from the engines of the aircrafts. Our results show that despite their small size, local airports serving remote insular regions should be considered as important air pollution hotspots, raising concerns for the exposure of the people working and leaving in their vicinities to hazardous pollutants.

Assessment of PM2.5 sources and their corresponding level of uncertainty in a coastal urban area using EPA PMF 5.0 enhanced diagnostics.

Datasets that include only the PM elemental composition and no other important constituents such as ions and OC, should be treated carefully when used for source apportionment. This work is demonstrating how a source apportionment study utilizing PMF 5.0 enhanced diagnostic tools can achieve an improved solution with documented levels of uncertainty for such a dataset. The uncertainty of the solution is rarely reported in source apportionment studies or it is reported partially. Reporting the uncertainty of the solution is very important especially in the case of small datasets. PM2.5 samples collected in Patras during the year 2011 were used. The concentrations of 22 elements (Z=11-33) were determined using PIXE. Source apportionment analysis revealed that PM2.5 emission sources were biomass burning (11%), sea salt (8%), shipping emissions (10%), vehicle emissions (33%), mineral dust (2%) and secondary sulfates (33%) while unaccounted mass was 3%. Although Patras city center is located in a very close proximity to the city's harbor, the contribution of shipping originating emissions was never before quantified. As rotational stability is hard to be achieved when a small dataset is used the rotational stability of the solution was thoroughly evaluated. A number of constraints were applied to the solution in order to reduce rotational ambiguity.

Determination of water-soluble and insoluble elements in PM2.5 by ICP-MS.

The elemental composition of water-soluble and acid-soluble fractions of PM2.5 samples from two different Greek cities (Patras and Megalopolis) was investigated. Patras and Megalopolis represent different environments. Specifically, Patras is an urban environment with proximity to a large port, while Megalopolis is a small city located close to lignite power plants. Both cities can serve as a representative example of European cities with similar characteristics. The concentration of 14 elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Fe, Sr, Ti, V and Zn) was determined in each fraction by ICP-MS. Microwave assisted digestion was used to digest the samples using a mixture of HNO3 and HF. For the determination of the water soluble fraction, water was chosen as the simplest and most universal extraction solvent. For the validation of the extraction procedure, the recoveries were tested on two certified reference materials (NIST SRM 1648 Urban Particulate Matter and NIST 1649a Urban Dust). Results showed that Zn has the highest total concentration (273 and 186 ng/m(3)) and Co the lowest (0.48 and 0.23 ng/m(3)) for Patras and Megalopolis samples, respectively. Nickel with 65% for Patras and As with 49% for Megalopolis displayed the highest solubility, whereas Fe (10%) and Ti (2%) the lowest ones, respectively.

Spatial and vertical distribution and risk assessment of natural radionuclides in soils surrounding the lignite-fired power plants in Megalopolis basin, Greece.

Twenty soil profile samples and fourteen surface soil samples collected from the vicinity of the lignite-fired power plants in the Megalopolis basin (Greece) were analysed for their natural radionuclide concentration and (137)Cs, since fossil fuels are associated with naturally occurring radioactive materials and hence with radiological impact. No significant enhancement of surface soil radioactivity levels in the vicinity of lignite-fired plants was observed. A downcore decreasing trend of (137)Cs was observed in a number of cores reflecting its atmospheric origin, whereas the uniform distribution observed in a number of other cores gave information on the mechanical alteration of the soil. The average dose rate value was found to be 63 ± 22 nGy h(-1), while the annual average effective dose from the terrestrial gamma radiation was found to be 0.08 ± 0.03 mSv.