Exposure to particulate matter (PM) has been associated with adverse health outcomes, particularly in susceptible population groups such as children. This study aims to characterise children's ...exposure to PM and its chemical constituents. Size-segregated aerosol samples (PM0.25, PM0.25–0.5, PM0.5–1.0, PM1.0–2.5 and PM2.5–10) were collected in the indoor and outdoor of homes and schools located in Lisbon (Portugal). Organic and elemental carbon (OC and EC) were determined by a thermo-optical method, whereas major and trace elements were analysed by X-Ray Fluorescence. In school, the children were exposed to higher PM concentrations than in home, which might be associated not only to the elevated human occupancy but also to outdoor infiltration. The pattern of PM mass size distribution was dependent on the location (home vs. school and indoor vs. outdoor). The presence of EC in PM0.25 and OC in PM0.25–0.5 was linked to traffic exhaust emissions. OC and EC in PM2.5–10 may be explained by their adhesion to the surface of coarser particles. Generally, the concentrations of mineral and marine elements increased with increasing PM size, while for anthropogenic elements happened the opposite. In schools, the concentrations of mineral matter, anthropogenic elements and marine aerosol were higher than in homes. High mineral matter concentrations found in schools were related to the close proximity to busy roads and elevated human occupancy. Overall, the results suggest that exposure to PM is relevant and highlights the need for strategies that provide healthier indoor environments, principally in schools.
•Assessment of concentrations and chemical composition of PM in homes and schools.•In school the children were exposed to much higher PM concentrations than in home.•PM concentrations were frequently higher indoors than outdoors.•PM mass size distribution depended on the location (home vs. school; indoor vs. outdoor).•Contributions from chemical constituents varied by PM size.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
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.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The main objective of this study was chemical characterization and source apportionment of the oxidative potential of ambient PM2.5 samples collected in an urban background area in Athens, Greece. ...Ambient PM2.5 samples were collected during the summer (June–September) of 2017 and winter (February–March) of 2018 at a residential, urban background site in the outlying neighborhood of the Demokritos National Laboratory in Athens, Greece. The collected PM samples were analyzed for their chemical constituents including metals and trace elements, water-soluble organic carbon (WSOC), elemental and organic carbon (EC/OC), and marker of biomass burning (i.e., levoglucosan). In addition, the DCFH in vitro assay was performed to determine the oxidative potential of the PM2.5 samples. We performed a series of statistical analyses, including Spearman rank-order correlation analysis, principal component analysis (PCA), and multi linear regression (MLR) to determine the most significant species (as source tracers) contributing to the oxidative potential of PM2.5. Our findings revealed that the intrinsic (per PM mass) and extrinsic (per m3 of air volume) oxidative potentials of the collected ambient PM2.5 samples were significantly higher than those measured in many urban areas around the world. The results of the MLR analyses indicated that the major pollution sources contributing to the oxidative potential of ambient PM2.5 were vehicular emissions (characterized by EC) (44%), followed by secondary organic aerosol (SOA) formation (characterized by WSOC) (16%), and biomass burning (characterized by levoglucosan) (9%). The oxidative potential of the collected ambient PM2.5 samples was also higher in summer compared to the winter, mainly due to higher concentrations of EC and WSOC during this season. Results from this study corroborate the impact of traffic and SOA on the oxidative potential of ambient PM2.5 in greater Athens area, and can be helpful in adopting appropriate public health policies regarding detrimental outcomes of exposure to PM2.5.
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•Sources of the PM2.5 oxidative potential (OP) were determined in a suburban site in Athens.•We used a combination of PCA and MLR to perform OP source apportionment.•Vehicular emissions was found to be the major contributor to PM2.5 OP.•SOA and biomass burning were the next major contributors to PM2.5 OP.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We studied the influence of the Planetary Boundary Layer (PBL) on the air masses sampled at the mountaintop Hellenic Atmospheric Aerosol and Climate Change station ((HAC)2) at Mount Helmos (Greece) ...during the Cloud-AerosoL InteractionS in the Helmos background TropOsphere (CALISTHO) Campaign from September 2021 to March 2022. The PBL Height (PBLH) was determined from the standard deviation of the vertical wind velocity (σw) measured by a wind Doppler lidar (over a 30-min time window with 30 m spatial resolution); the height for which σw drops below a characteristic threshold of 0.1 m s–1 corresponds to the PBLH. The air mass characterization is independently carried out using in situ measurements sampled at (HAC)2 (equivalent black carbon, eBC; fluorescent particle number, aerosol size distributions, absolute humidity). We found that a distinct diurnal cycle of aerosol properties is seen when the station is inside the PBL (i.e., PBLH exceeds the (HAC)2 altitude); and a complete lack thereof when it is in the Free Tropospheric Layer (FTL). Additionally, we identified transition periods where the (HAC)2 site location alternates between the FTL (usually during the early morning hours) and the PBL (usually during the midday and late afternoon hours), during which the concentration and characteristics of the aerosols vary the most. Transition periods are also when orographic clouds are formed. The highest PBLH values occur in September 400 m above (HAC)2 followed by a transition period in November, while the lowest ones occur in January 200 m below (HAC)2. We found also that the PBLH increases by 16 m per 1°C increase of the ground temperature.
The objective of this work was to assess the yearly contribution of fossil fuel combustion (BCff) and wood burning (BCwb) to equivalent black carbon (eBC) concentrations, in Athens, Greece. ...Measurements were conducted at a suburban site from March 2013 to February 2014 and included absorption coefficients at seven wavelengths and PM2.5 chemical composition data for key biomass burning markers, i.e., levoglucosan, potassium (K) and elemental and organic carbon (EC, OC). A well-documented methodology of corrections for aethalometer attenuation coefficients was applied with a resulting annual dataset of derived absorption coefficients for the suburban Athens’ atmospheric aerosol. The Aethalometer model was applied for the source apportionment of eBC. An optimum Ångström exponent for fossil fuel (αff) was found, based on the combined use of the model with levoglucosan data. The measured eBC concentrations were equal to 2.4 ± 1.0 μg m−3 and 1.6 ± 0.6 μg m−3, during the cold and the warm period respectively. The contribution from wood burning was significantly higher during the cold period (21 ± 11%, versus 6 ± 7% in the warm period). BCff displayed a clear diurnal pattern with a morning peak between 8 and 10 a.m. (during morning rush hour) and a second peak during the evening and night hours, due to the shallowing of the mixing layer. Regression analysis between BCwb concentrations and biomass burning markers (levoglucosan, K and OC/EC ratio) supported the validity of the results.
Moss biomonitoring is a widely used technique for monitoring the accumulation of trace elements in airborne pollution. A total of one hundred and five samples, mainly of the Hypnum cupressiforme ...Hedw. moss species, were collected from the Northern Greece during the 2015/2016 European ICP Vegetation (International Cooperative Program on Effects of Air Pollution on Natural Vegetation and Crops) moss survey, which also included samples from the metalipherous area of Skouries. They were analyzed by means of neutron activation analysis, and the elemental concentrations were determined. A positive matrix factorization (PMF) model was applied to the results obtained for source apportionment. According to the PMF model, five sources were identified: soil dust, aged sea salt, road dust, lignite power plants, and a Mn-rich source. The soil dust source contributed the most to almost all samples (46% of elemental concentrations, on average). Two areas with significant impact from anthropogenic activities were identified. In West Macedonia, the emissions from a lignite power plant complex located in the area have caused high concentrations of Ni, V, Cr, and Co. The second most impacted area was Skouries, where mining activities and vehicular traffic (probably related to the mining operations) led to high concentrations of Mn, Ni, V, Co, Sb, and Cr.
Impact of traditional biomass burning activities on regional air quality is a major environmental concern. Measurement campaigns were performed during post-harvesting activities in the Ba Vi region ...in Hanoi in May-June of 2015 and 2016. To quantify the source for regional haze the sampling of rice straw burning emissions was performed on fields. Carbonaceous (OC, EC, BrC) fractions, heavy metals, organic and ionic composition, and microstructure were characterized. A set of functionalities (hydroxyl, aliphatic, carbonyl, carboxylate, and nitro groups) revealed a functional marker of pile combustion. Optical, microstructural, and chemical analyses of environmentally-dangerous pollutants from traffic and cooking sources provided characteristics and functional markers of different pollution sources. Chemical features of rice straw burning were identified on the Ba Vi site during the haze episode of 2015, when PM_(10) mass approached the high smoke intensity, up to 167 μg m^(-3). Small-scale meteorology affected PM_(10), OC and EC, and ion mass in days of highest relative humidity and fogs. In days of highest smoke OC dominated PM_(10) mass by up to 42%, the OC/EC ratio approached 20, in line with observations of mainly smoldering emissions across the fields. Spectral features of regional haze smoke demonstrated the absorption of rice straw burning whereas the impact of biogenic, traffic, and cooking sources were significantly lower. Individual particle analyses showed carbonaceous particles internally/externally mixed with inorganic fly ash and dust. Smoke micromarkers revealed the microstructure of regional aerosols representative for Southeast Asia in BB periods. Significantly lower PM_(10) mass concentrations and strong difference in aerosol composition before post-harvesting activities suggested that agricultural burning represents a large contribution to air quality degradation in the rural area of Vietnam.
Aerosol hygroscopicity is a key aerosol property, influencing a number of other physical properties, and the impacts of PM pollution on the environment, climate change, and health. The present work ...aims to provide insight into the contribution of major PM sources to aerosol hygroscopicity, focusing on an urban background site, with a significant impact from both primary and secondary sources. The EPA PMF 5.0 model was applied to PM2.5 chemical composition and hygroscopicity data collected from August 2016 to July 2017 in Athens, Greece. Source apportionment analysis resulted in six major sources, including four anthropogenic sources (vehicular exhaust and non-exhaust, heavy oil combustion, and a mixed source of secondary aerosol formation and biomass burning) and two natural sources (mineral dust and aged sea salt). The mixed source was found to be the main contributor to PM2.5 levels (44%), followed by heavy oil combustion (26%) and vehicular traffic exhaust and non-exhaust emissions (15%). The aerosol hygroscopic growth factor (GF) was found to be mainly associated with the mixed source (by 36%) and heavy oil combustion (by 24%) and, to a lesser extent, with vehicle exhaust (by 19%), aged sea salt (by 14%), and vehicle non-exhaust (by 6%).
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