Sources of atmospheric aerosol from long-term measurements (5 years) of chemical composition in Athens, Greece

Variations in the concentration, source activity, and atmospheric processing of PM2.5-associated water-soluble ionic species over Jammu, India

Concentrations, sources, and atmospheric processing of water-soluble ionic species associated with PM_2.5 collected from 2015 to 2017 were studied in Jammu, an urban location in the North-Western Himalayan Region (NWHR). Being ecologically sensitive and sparsely studied for dynamics in PM_2.5 and associated WSIS, the present study is important for developing robust air pollution abatement strategies for the air-shed of NWHR. Twenty-four hourly PM_2.5 samples were collected on weekly basis at a receptor site and analyzed for WSIS using ion chromatography system. On annual basis, total sum of WSIS (ΣWSIS) contributed about 28.5% of PM_2.5, where the contribution of sulfate-nitrate-ammonium, a proxy for secondary inorganic aerosols (SIA), was found to be 18.7% of PM_2.5. The ΣWSIS and PM_2.5 concentration showed a seasonal cycle with the maximum concentration during winters and the minimum in summers. Mass fraction of ΣWSIS in PM_2.5 showed an anti-phase seasonal pattern indicating more source activity during summers. Season-wise, dominant WSIS constituting PM_2.5 were NO₃^-, SO₄^2-, NH₄⁺, and K⁺ during winters; whereas summer was marked with dominant contributions from SO₄^2-, NH₄⁺, Ca²⁺, and K⁺. Seasonal variability exhibited among SIA constituents underscored the crucial role of air temperature and relative humidity regime. It was observed that nss-K⁺ + NH₄⁺ were sufficient to neutralize most of the acidic species arising from precursor gases (NO_x and SO_x). Using principal component analysis, five major sources and processes, viz. (a) biomass burning activities, (b) secondary inorganic aerosol formation, (c) input from re-suspended dust, (d) transported dust, and (e) fertilizer residue, were identified for the emissions of PM_2.5-associated WSIS over Jammu. In future studies, impacts of dry and/or wet deposition of aerosol-associated WSIS on the crop productivity in the region should be studied.

Particulate Matter (PM2.5) Characterization, Air Quality Level and Origin of Air Masses in an Urban Background in Pretoria

Several sources have been identified as contributing to the concentration of ambient fine particulate matter, which has been associated to a variety of health issues. The chemical characteristics and sources of trace elements in PM_2.5, as well as the air quality index, were investigated in this study. Twenty four-hour fine aerosol particles were collected in an urban area in Pretoria, South Africa, from April 2017 to April 2018. Eighteen trace elements were determined using an XEPOS 5 energy-dispersive X-ray fluorescence (EDXRF) spectrometer, while black and organic carbon were estimated using an optical transmissometer from the samples collected. The HYPLIT model (version 4.9) was used to estimate air mass trajectories. Health risk was calculated by comparing it to the World Health Organization's air quality index (AQI). The overall mean PM_2.5 concentration of the collected sample equals 21 µg/m³. Majority of PM_2.5 exceedances were reported during mid-autumn and winter seasons, as compared to daily WHO guidelines and South African standards. S had the highest concentrations, greater than 1 µg/m³. Ni, Se, Br and Sb showed they were extremely enriched, (EF > 10) and suggestive of anthropogenic or non crustal origin The 24-h PM, soot, BC and OC were significantly different by the geographical origin of air masses (p < 0.05). The AQI showed that 70% of the samples showed levels above the AQI range of good and healthy air. The findings include details on the concentration, composition, and potential sources of fine PM_2.5, which is essential for policy formulation and mitigation strategies in South Africa's fight against air pollution.

Pollution characteristics and sources of environmentally persistent free radicals and oxidation potential in fine particulate matter related to city lockdown (CLD) in Xi'an, China

The impact of COVID-19 control on air quality have been prevalent for the past two years, however few studies have explored the toxicity of atmospheric particulate matter during the epidemic control. Therefore, this research highlights the characteristics and sources of oxidative potential (OP) and the new health risk substances environmentally persistent free radicals (EPFRs) in comparison to city lockdown (CLD) with early days of 2019-2020. Daily particulate matter (PM_2.5) samples were collected from January 14 to February 3, 2020, with the same period during 2019 in Xi'an city. The results indicated that the average concentration of PM_2.5 decreased by 48% during CLD. Concentrations of other air pollutants and components, such as PM₁₀, NO₂, SO₂, WSIs, OC and EC were also decreased by 22%, 19%, 2%, 17%, 6%, and 4% respectively during the CLD, compared to the same period in 2019. Whereas only O₃ increased by 30% during CLD. The concentrations of EPFRs in PM_2.5 was considerably lower than in 2019, which decreased by 12% during CLD. However, the OP level was increased slightly during CLD. Moreover, both EPFRs/PM and DTTv/PM did not decrease or even increase significantly, manifesting that the toxicity of particulate matter has not been reduced by more gains during the CLD. Based on PMF analysis, during the epidemic period, the contribution of traffic emission is significantly reduced, while EPFRs and DTTv increased, which consist of significant O₃ and secondary aerosols. This research leads to able future research on human health effect of EPFRs and oxidative potential and can be also used to formulate the majors to control EPFRs and OP emissions, suggest the need for further studies on the secondary processing of EPFRs and OP during the lockdown period in Xi'an. .The COVID-19 lockdown had a significant impact on both social and economic aspects. The city lockdown, however, had a positive impact on the environment and improved air quality, however, no significant health benefits were observed in Xi'an, China.

Impact of COVID-19 Lockdown on Oxidative Potential of Particulate Matter: Case of Athens (Greece)

This work evaluates the aerosol oxidative potential (OP) and its changes from modified air pollution emissions during the COVID-19 lockdown period in 2020, with the intent of elucidating the contribution of aerosol sources and related components to aerosol OP. For this, daily particulate matter (PM) samples at an urban background site were collected and analyzed with a chemical (acellular) assay based on Dithiothreitol (DTT) during the COVID-19 restriction period in Athens (Greece). The obtained time-series of OP, PM2.5, organic matter (OM) and SO42− of the pre-, post- and lockdown periods were also compared to the data of the same time periods during the years 2017–2019. Even though all traffic-related emissions have been significantly reduced during the lockdown period (by 30%), there is no reduction in water-soluble OP, organics and sulfate concentrations of aerosol during 2020. The results reveal that the decrease in traffic was not sufficient to drive any measurable change on OP, suggesting that other sources—such as biomass burning and secondary aerosol from long-range transport, which remained unchanged during the COVID lockdown—are the main contributors to OP in Athens, Greece.

Saccharides as Particulate Matter Tracers of Biomass Burning: A Review

The adverse effects of atmospheric particulate matter (PM) on health and ecosystems, as well as on meteorology and climate change, are well known to the scientific community. It is therefore undeniable that a good understanding of the sources of PM is crucial for effective control of emissions and to protect public health. One of the major contributions to atmospheric PM is biomass burning, a practice used both in agriculture and home heating, which can be traced and identified by analyzing sugars emitted from the combustion of cellulose and hemicellulose that make up biomass. In this review comparing almost 200 selected articles, we highlight the most recent studies that broaden such category of tracers, covering research publications on residential wood combustions, open-fire or combustion chamber burnings and ambient PM in different regions of Asia, America and Europe. The purpose of the present work is to collect data in the literature that indicate a direct correspondence between biomass burning and saccharides emitted into the atmosphere with regard to distinguishing common sugars attributed to biomass burning from those that have co-causes of issue. In this paper, we provide a list of 24 compounds, including those most commonly recognized as biomass burning tracers (i.e., levoglucosan, mannosan and galactosan), from which it emerges that monosaccharide anhydrides, sugar alcohols and primary sugars have been widely reported as organic tracers for biomass combustion, although it has also been shown that emissions of these compounds depend not only on combustion characteristics and equipment but also on fuel type, combustion quality and weather conditions. Although it appears that it is currently not possible to define a single compound as a universal indicator of biomass combustion, this review provides a valuable tool for the collection of information in the literature and identifies analytes that can lead to the determination of patterns for the distribution between PM generated by biomass combustion.

Characterization of Aerosol Pollution in Two Hungarian Cities in Winter 2009–2010

In this study, atmospheric particulate matter (APM) pollution was compared in urban background sites of two cities in Hungary—namely the capital Budapest and Debrecen—by analyzing daily aerosol samples collected between 8 December 2009 and 18 March 2010. Concentration, elemental composition, including BC, and sources of fine (PM2.5) and coarse (PM2.5–10) aerosol pollution, as well as their variation due to meteorological conditions and anthropogenic activities, were determined for both cities. The average PM2.5 concentrations were 22 μg/m3 and 17 μg/m3 in Budapest and Debrecen, respectively. In the case of PM10, the mean concentration was 32 μg/m3 in Budapest and 23 μg/m3 in Debrecen. The concentration of the coarse fraction decreased significantly over the weekends compared to working days. The number of exceedances of the WHO recommended limit value for PM2.5 (15 μg/m3) were 67 in Budapest and 46 in Debrecen, which corresponds to 73% and 50% of the sampling days, respectively. At the time of the exceedances the daily average temperature was below freezing. The average PM2.5/PM10 ratio was 70% and 75% for the two sites, indicating the dominance of the fine fraction aerosol particles during the study period. Elements of natural origin (Al, Si, Ca, Ti, Mn, Fe, Ba) and chlorine were found to be dominant in the coarse fraction, while elements of anthropogenic origin (S, K, Cu, Zn, Pb) were characteristic to the fine fraction. Similar concentrations were measured in the two cities in the case of S which originates from regional transport and K which serves as a tracer for biomass combustion. Traffic-related elements were present in 2–3 times higher concentrations in Budapest. The episodic peaks in the Cl time series could be attributed to salting after snowfalls. The following sources of APM pollution were identified by using the EPA Positive Matrix Factorization (PMF) 5.0 receptor model: soil, traffic, road dust, secondary sulfate, biomass burning, and de-icing of streets. On polluted days when the PM2.5 concentration exceeded the 25 μg/m3 value the contribution of secondary sulfate, domestic heating, and traffic increased significantly compared to the average. On weekends and holidays the contribution of soil and traffic decreased. The main pollution sources and their contributions were similar to the ones in other cities in the region. Comparing our findings to results from winter 2015 it can be concluded that while the PM2.5 pollution level remained almost the same, a significant increase in the contribution of biomass burning was observed in both cities from 2010 to 2015, indicating a change of heating habits.

High-Resolution Measurements of SO2, HNO3 and HCl at the Urban Environment of Athens, Greece: Levels, Variability and Gas to Particle Partitioning

High-resolution measurements of sulfur dioxide (SO2), nitric acid (HNO3), and hydrochloric acid (HCl) were conducted in Athens, Greece, from 2014 to 2016 via a wet rotating annular denuder system paired with an ion chromatograph. Decreased mean annual levels of SO2 and HNO3 (equal to 3.3 ± 4.8 μg m−3 and 0.7 ± 0.6 μg m−3, respectively) were observed relative to the past, whereas for HCl (mean of 0.4 μg m−3 ) no such comparison was possible as the past measurements are very scarce. Regional and local emission sources regulated the SO2 levels and contributed to both the December and the July maxima of 6.6 μg m−3 and 5.5 μg m−3, respectively. Similarly, the significant enhancement at noon and during the winter nighttime was due to transported SO2 and residential heating, respectively. The oxidation of NO2 by OH radicals and the heterogeneous reactions of HNO3 on sea salt seemed to drive the HNO3 and HCl formation, respectively, whereas nighttime biomass burning affected only the former by almost 50%. During summer, the sulfate anions dominated over the SO2, in contrast to the chloride and nitrate ions that prevailed during the winter and were linked to the aerosol acidity that influences their lifetime as well as their impact on ecosystems.

Apportionment of black and brown carbon spectral absorption sources in the urban environment of Athens, Greece, during winter

This study examines the spectral properties and source characteristics of absorbing aerosols (BC: Black Carbon; BrC: Brown Carbon, based on aethalometer measurements) in the urban background of Athens during December 2016-February 2017. Using common assumptions regarding the spectral dependence of absorption due to BC (AAE_BC = 1) and biomass burning (AAE_bb = 2), and calculating an optimal AAE_ff value for the dataset (1.18), the total spectral absorption was decomposed into five components, corresponding to absorption of BC and BrC from fossil-fuel (ff) combustion and biomass burning (bb), and to secondary BrC estimated using the BC-tracer minimum R-squared (MRS) method. Substantial differences in the contribution of various components to the total absorption were found between day and night, due to differences in emissions and meteorological dynamics, while BrC and biomass burning aerosols presented higher contributions at shorter wavelengths. At 370 nm, the absorption due to BC_ff contributed 36.3% on average, exhibiting a higher fraction (58.1%) during daytime, while the mean BC_bb absorption was estimated at 18.4%. The mean absorption contributions due to BrC_ff, BrC_bb and BrC_sec were 6.7%, 32.3% and 4.9%, respectively. The AbsBC_ff,370 component maximized during the morning traffic hours and was strongly correlated with NO_x (R² = 0.76) and CO (R² = 0.77), while a similar behavior was seen for the AbsBrC_ff,370 component. AbsBC_bb and AbsBrC_bb levels escalated during nighttime and were highly associated with nss-K⁺ and with the organic aerosol (OA) components related to fresh and fast-oxidized biomass burning (BBOA and SV-OOA) as obtained from ACSM measurements. Multiple linear regression was used to attribute BrC absorption to five OA components and to determine their absorption contributions and efficiencies, revealing maximum contributions of BBOA (33%) and SV-OOA (21%). Sensitivity analysis was performed in view of the methodological uncertainties and supported the reliability of the results, which can have important implications for radiative transfer models.

Longitudinal Trends of the Annual Exposure to PM2.5 Particles in European Countries

BACKGROUND

PM_2.5 emission is known as a major challenge to environmental health and is the cause of approximately 7 million deaths annually. This study aimed at investigating the main patterns of PM_2.5 trend changes among European countries.

METHODS

The annual exposure to PM_2.5 pollutants was retrieved from the World Bank for 41 countries during 2010 to 2017, and a latent growth model was applied to identify the main patterns using Mplus 7.4 software.

RESULTS

Monitoring the overall mean annual exposure to PM_2.5 in the Europe showed a downward pattern with an annual decrease of 2.48% during the study period. Turkey had the highest PM_2.5 exposure with 43.82 μg/m³ in 2010, reaching 44.31 μg/m³ in 2017. Likewise, with 7.19 μg/m³ in 2010, Finland had the lowest exposure level which decreased to 5.86 μg/m³ in 2017. Two main patterns for the mean annual PM_2.5 exposure were identified via the latent growth model. Countries in the first pattern, including Turkey and Ukraine, had experienced a slow annual increase in the mean exposure of PM_2.5 pollutant. Likewise, the other 39 countries belonged to the second pattern with a moderate falling trend in the mean exposure to PM_2.5.

CONCLUSION

Although the trend changes of mean annual exposure to PM_2.5 in Europe were falling, Turkey and Ukraine had experienced a slow annual increase. It is advisable to take appropriate measures to curb the current raising exposure to PM_2.5 in Turkey and Ukraine.

Distribution of bacterial concentration and viability in atmospheric aerosols under various weather conditions in the coastal region of China

Airborne bacteria have an important role in atmospheric processes and human health. However, there is still little information on the transmission and distribution of bacteria via the airborne route. To characterize the impact of foggy, haze, haze-fog (HF) and dust days on the concentration and viability of bacteria in atmospheric aerosols, size-segregated bioaerosol samples were collected in the Qingdao coastal region from March 2018 to February 2019. The total airborne microbes and viable/non-viable bacteria in the bioaerosol samples were measured using an epifluorescence microscope after staining with DAPI (4', 6-diamidino-2-phenylindole) and a LIVE/DEAD® BacLight Bacterial Viability Kit. The average concentrations of total airborne microbes on haze and dust days were 6.75 × 10⁵ and 1.03 × 10⁶ cells/m³, respectively, which increased by a factor of 1.3 and 2.5 (on average), respectively, relative to those on sunny days. The concentrations of non-viable bacteria on haze and dust days increased by a factor of 1.2 and 3.6 (on average), respectively, relative to those on sunny days. In contrast, the concentrations of viable bacteria on foggy and HF days were 7.13 × 10³ and 5.74 × 10³ cells/m³, decreases of 38% and 50%, respectively, compared with those on sunny days. Foggy, haze, dust and HF days had a significant effect on the trend of the seasonal variation in the total airborne microbes and non-viable bacteria. Bacterial viability was 20.8% on sunny days and significantly higher than the 14.1% on foggy days, 11.2% on haze days, 8.6% during the HF phenomenon and 6.1% on dust days, indicating that special weather is harmful to some bacterial species. Correlation analysis showed that the factors that influenced the bacterial concentration and viability depended on different weather conditions. The main influential factors were temperature, NO₂ and SO₂ concentrations on haze days, and temperature, particulate matter (PM_2.5) and NO₂ concentrations on foggy days. The median size of particles containing viable bacteria was 1.94 μm on sunny days and decreased to 1.88 μm and 1.74 μm on foggy and haze days, respectively, but increased to 2.18 μm and 2.37 μm on dust and HF days, respectively.

Observations of Gas-Phase Alkylamines at a Coastal Site in the East Mediterranean Atmosphere

Atmospheric amines are ubiquitous compounds in the atmosphere, having both natural and anthropogenic origin. Recently, they have been identified as important contributors to new particle formation in the atmosphere, but observations of their atmospheric concentrations are scarce. In the present study we introduce the first systematic long-term observations of gas-phase amines measurements in the East Mediterranean atmosphere. Air samples were collected at the Finokalia monitoring station of the University of Crete during a 3.5-year period from January 2013 to July 2016, and analyzed after extraction using a high-performance liquid chromatography triple quadrupole mass spectrometer. The detected alkylamines were the sum of dimethylamine and ethylamine (DMA+EA), trimethylamine (TMA), diethylamine (DEA) and triethylamine (TEA). DMA+EA and TMA were the most abundant alkylamines, with concentrations spanning from the detection limit to 78.0 and 69.8 pptv, and average concentrations of 7.8 ± 12.1 and 7.5 ± 12.4 pptv, respectively. Amines showed pronounced seasonal variability with DMA+EA and TMA concentrations being higher in winter. Statistical analysis of the observations showed different sources for each of the studied amines, except for DMA+ΕA and DEA that appear to have common sources in the region. This analysis points to a marine source of TMA and animal husbandry in the area as a potential source of TEA. None of the alkylamines is correlated with other anthropogenic sources. Furthermore, no clear association was found between the seasonality of NPF events and alkylamines concentrations, while a clear correlation was detected between the seasonality of nucleation mode particle (dp < 25 nm) number concentrations and alkylamine concentrations, indicating that amines may contribute to nucleation mode particles’ production.

The UrbEm Hybrid Method to Derive High-Resolution Emissions for City-Scale Air Quality Modeling

As cities are growing in size and complexity, the estimation of air pollution exposure requires a detailed spatial representation of air pollution levels, rather than homogenous fields, provided by global- or regional-scale models. A critical input for city-scale modeling is a timely and spatially resolved emission inventory. Bottom–up approaches to create urban-scale emission inventories can be a demanding and time-consuming task, whereas local emission rates derived from a top–down approach may lack accuracy. In the frame of this study, the UrbEm approach of downscaling gridded emission inventories is developed, investing upon existing, open access, and credible emission data sources. As a proof-of-concept, the regional anthropogenic emissions by Copernicus Atmospheric Monitoring Service (CAMS) are handled with a top–down approach, creating an added-value product of anthropogenic emissions of trace gases and particulate matter for any city (or area) of Europe, at the desired spatial resolution down to 1 km. The disaggregation is based on contemporary proxies for the European area (e.g., Global Human Settlement population data, Urban Atlas 2012, Corine, OpenStreetMap data). The UrbEm approach is realized as a fully automated software tool to produce a detailed mapping of industrial (point), (road-) transport (line), and residential/agricultural/other (area) emission sources. Line sources are of particular value for air quality studies at the urban scale, as they enable explicit treatment of line sources by models capturing among others the street canyon effect and offer an overall better representation of the critical road transport sector. The UrbEm approach is an efficient solution for such studies and constitutes a fully credible option in case high-resolution emission inventories do not exist for a city (or area) of interest. The validity of UrbEm is examined through the evaluation of high-resolution air pollution predictions over Athens and Hamburg against in situ measurements. In addition to a better spatial representation of emission sources and especially hotspots, the air quality modeling results show that UrbEm outputs, when compared to a uniform spatial disaggregation, have an impact on NO2 predictions up to 70% for urban regions with complex topographies, which corresponds to a big improvement of model accuracy (FAC2 > 0.5), especially at the source-impacted sites.

Chemical Composition and Source Apportionment of Total Suspended Particulate in the Central Himalayan Region

The present study analyzes data from total suspended particulate (TSP) samples collected during 3 years (2005–2008) at Nainital, central Himalayas, India and analyzed for carbonaceous aerosols (organic carbon (OC) and elemental carbon (EC)) and inorganic species, focusing on the assessment of primary and secondary organic carbon contributions (POC, SOC, respectively) and on source apportionment by positive matrix factorization (PMF). An average TSP concentration of 69.6 ± 51.8 µg m−3 was found, exhibiting a pre-monsoon (March–May) maximum (92.9 ± 48.5 µg m−3) due to dust transport and forest fires and a monsoon (June–August) minimum due to atmospheric washout, while carbonaceous aerosols and inorganic species expressed a similar seasonality. The mean OC/EC ratio (8.0 ± 3.3) and the good correlations between OC, EC, and nss-K+ suggested that biomass burning (BB) was one of the major contributing factors to aerosols in Nainital. Using the EC tracer method, along with several approaches for the determination of the (OC/EC)pri ratio, the estimated SOC component accounted for ~25% (19.3–29.7%). Furthermore, TSP source apportionment via PMF allowed for a better understanding of the aerosol sources in the Central Himalayan region. The key aerosol sources over Nainital were BB (27%), secondary sulfate (20%), secondary nitrate (9%), mineral dust (34%), and long-range transported mixed marine aerosol (10%). The potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analyses were also used to identify the probable regional source areas of resolved aerosol sources. The main source regions for aerosols in Nainital were the plains in northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area. The outcomes of the present study are expected to elucidate the atmospheric chemistry, emission source origins, and transport pathways of aerosols over the central Himalayan region.

PM1 chemical composition and light absorption properties in urban and rural areas within Sichuan Basin, southwest China

Sichuan Basin is encircled by high mountains and plateaus with the heights ranging from 1 km to 3 km, and is one of the most polluted regions in China. However, the dominant chemical species and light absorption properties of aerosol particles is still not clear in rural areas. Chemical composition in PM₁ (airborne particulate matter with an aerodynamic diameter less than 1 μm) and light-absorbing properties were determined in Chengdu (urban) and Sanbacun (rural) in western Sichuan Basin (WSB), Southwest China. Carbonaceous aerosols and secondary inorganic ions (NH₄⁺, NO₃^- and SO₄^2-) dominate PM₁ pollution, contributing more than 85% to PM₁ mass at WSB. The mean concentrations of organic and elemental carbon (OC, EC), K⁺ and Cl^- are 19.69 μg m^-3, 8.00 μg m^-3, 1.32 μg m^-3, 1.16 μg m^-3 at the rural site, which are 26.2%, 65.3%, 34.7% and 48.7% higher than those at the urban site, respectively. BrC (brown carbon) light absorption coefficient at 405 nm is 63.90 ± 27.81 M m^-1 at the rural site, contributing more than half of total absorption, which is about five times higher than that at urban site (10.43 ± 4.74 M m^-1). Compared with secondary OC, rural BrC light absorption more depends on primary OC from biomass and coal burning. The rural MAE_BrC (BrC mass absorption efficiency) at 405 nm ranges from 0.6 to 5.1 m² g^-1 with mean value of 3.5 ± 0.8 m² g^-1, which is about three times higher than the urban site.

Heart Failure and PAHs, OHPAHs, and Trace Elements Levels in Human Serum: Results from a Preliminary Pilot Study in Greek Population and the Possible Impact of Air Pollution

Cardiovascular diseases (CVDs) have been associated with environmental pollutants. The scope of this study is to assess any potential relation of polycyclic aromatic hydrocarbons (PAHs), their hydroxylated derivatives, and trace elements with heart failure via their direct determination in human serum of Greek citizens residing in different areas. Therefore, we analyzed 131 samples including cases (heart failure patients) and controls (healthy donors), and the respective demographic data were collected. Significantly higher concentrations (p < 0.05) were observed in cases' serum regarding most of the examined PAHs and their derivatives with phenanthrene, fluorene, and fluoranthene being the most abundant (median of >50 μg L-1). Among the examined trace elements, As, Cd, Cu, Hg, Ni, and Pb were measured at statistically higher concentrations (p < 0.05) in cases' samples, with only Cr being significantly higher in controls. The potential impact of environmental factors such as smoking and area of residence has been evaluated. Specific PAHs and trace elements could be possibly related with heart failure development. Atmospheric degradation and smoking habit appeared to have a significant impact on the analytes' serum concentrations. PCA-logistic regression analysis could possibly reveal common mechanisms among the analytes enhancing the hypothesis that they may pose a significant risk for CVD development.

Assessment of the COVID-19 Lockdown Effects on Spectral Aerosol Scattering and Absorption Properties in Athens, Greece

COVID-19 is evolving into one of the worst pandemics in recent history, claiming a death toll of over 1.5 million as of December 2020. In an attempt to limit the expansion of the pandemic in its initial phase, nearly all countries imposed restriction measures, which resulted in an unprecedented reduction of air pollution. This study aims to assess the impact of the lockdown effects due to COVID-19 on in situ measured aerosol properties, namely spectral-scattering (bsca) and absorption (babs) coefficients, black carbon (BC) concentrations, single-scattering albedo (SSA), scattering and absorption Ångström exponents (SAE, AAE) in Athens, Greece. Moreover, a comparison is performed with the regional background site of Finokalia, Crete, for a better assessment of the urban impact on observed differences. The study examines pre-lockdown (1–22 March 2020), lockdown (23 March–3 May 2020) and post-lockdown (4–31 May 2020) periods, while the aerosol properties are also compared with a 3–4 year preceding period (2016/2017–2019). Comparison of meteorological parameters in Athens, between the lockdown period and respective days in previous years, showed only marginal variation, which is not deemed sufficient in order to justify the notable changes in aerosol concentrations and optical properties. The largest reduction during the lockdown period was observed for babs compared to the pre-lockdown (−39%) and to the same period in previous years (−36%). This was intensified during the morning traffic hours (−60%), reflecting the large decrease in vehicular emissions. Furthermore, AAE increased during the lockdown period due to reduced emissions from fossil-fuel combustion, while a smaller (−21%) decrease was observed for bsca along with slight increases (6%) in SAE and SSA values, indicating that scattering aerosol properties were less affected by the decrease in vehicular emissions, as they are more dependent on regional sources and atmospheric processing. Nighttime BC emissions related to residential wood-burning were slightly increased during the lockdown period, with respect to previous-year means. On the contrary, aerosol and pollution changes during the lockdown period at Finokalia were low and highly sensitive to natural sources and processes.

Characterization of aerosol sources in León (Spain) using Positive Matrix Factorization and weather types

A one-year aerosol sampling campaign, between 2016 and 2017, was conducted in a suburban area of León city, Spain. An association between the Positive Matrix Factorization (PMF) results and air masses through circulation weather types was carried out, through the construction of linear models from the PM₁₀ concentrations and its chemical composition. The aerosol sources, identified by PMF six-factor solution, were: traffic (29%), aged sea salt (26%), secondary aerosols (16%), dust (13%), marine aerosol (7%) and biomass burning (3%). Traffic and secondary factors showed the highest PM₁₀ contribution in the hybrid cyclonic types with wind component from the first and second quadrant. Anticyclonic types with wind component from the first quadrant exhibited high values of secondary, aged sea salt and dust factors. The highest contributions of the dust factor were also associated with northerly types. The linear models built for estimating the source apportionment of PM₁₀, from aerosol chemical composition and geostrophic flow, showed positive coefficients for: westerly flows (WF) in marine factor, southerly flows (SF) in secondary and traffic factors, and shear southerly vorticities (ZS) in dust factor. Negative dependences were observed for ZS in aged sea salt factor and for SF in dust factor. The PM₁₀ mass concentration calculated by the linear models and by the PMF model were strongly correlated. This can be very useful to determine the contribution of a specific source to PM₁₀ in León, only by knowing some meteorological and chemical variables.

Water-soluble ionic species in atmospheric aerosols over Dhauladhar region of North-Western Himalaya

Water-soluble ionic species (WSIS) have been used as potential markers for different source(s) and underlining process(es) emitting and transforming atmospheric aerosols. PM₁₀ aerosol sampling was performed once in a week for a complete one year, at a mid-altitude urban and a low-altitude rural location simultaneously in the Dhauladhar region of the North-Western Himalaya. Aerosol samples were analysed for major WSIS (anions: F^-, Cl^-, NO₃^-, PO₄^3- and SO₄^2-; cations: Na⁺, NH₄⁺, K⁺, Ca²⁺ and Mg²⁺) using the ion chromatography system. Results showed that WSIS constitutes around 15% of PM₁₀ aerosol load in the region. SO₄^2- contributes the maximum (~ 50%) followed by NO₃^- (~ 12.5%) and NH₄⁺ (~ 12.5%) to the total concentration of WSIS analysed. During all the seasons, average concentrations of PM₁₀ and associated WSIS were observed to be higher over the rural location in comparison to the urban location. The total concentration of WSIS was found to be maximum during the winter season. Principal component analysis performed on the WSIS concentration dataset revealed four major sources of PM₁₀-associated WSIS viz. re-suspension of soil or local sediments; conversion of pollutant gases (SO_x, NO_x and NH₃) to particles, i.e., secondary inorganic aerosol formation; evaporative loss or re-suspension of inorganic (NPK) fertilizers' residues and biomass/crop-residue burning emissions in the Dhauladhar region of the North-Western Himalaya.

Integrating in situ Measurements and City Scale Modelling to Assess the COVID–19 Lockdown Effects on Emissions and Air Quality in Athens, Greece

The lockdown measures implemented worldwide to slow the spread of the COVID–19 pandemic have allowed for a unique real-world experiment, regarding the impacts of drastic emission cutbacks on urban air quality. In this study we assess the effects of a 7-week (23 March–10 May 2020) lockdown in the Greater Area of Athens, coupling in situ observations with estimations from a meteorology-atmospheric chemistry model. Measurements in central Athens during the lockdown were compared with levels during the pre- and post-lockdown 3-week periods and with respective levels in the four previous years. We examined regulatory pollutants as well as CO2, black carbon (BC) and source-specific BC components. Models were run for pre-lockdown and lockdown periods, under baseline and reduced-emissions scenarios. The in-situ results indicate mean concentration reductions of 30–35% for traffic-related pollutants in Athens (NO2, CO, BC from fossil fuel combustion), compared to the pre-lockdown period. A large reduction (53%) was observed also for the urban CO2 enhancement while the reduction for PM2.5 was subtler (18%). Significant reductions were also observed when comparing the 2020 lockdown period with past years. However, levels rebounded immediately following the lift of the general lockdown. The decrease in measured NO2 concentrations was reproduced by the implementation of the city scale model, under a realistic reduced-emissions scenario for the lockdown period, anchored at a 46% decline of road transport activity. The model permitted the assessment of air quality improvements on a spatial scale, indicating that NO2 mean concentration reductions in areas of the Athens basin reached up to 50%. The findings suggest a potential for local traffic management strategies to reduce ambient exposure and to minimize exceedances of air quality standards for primary pollutants.

Field Evaluation of Low-Cost PM Sensors (Purple Air PA-II) Under Variable Urban Air Quality Conditions, in Greece

Recent advances in particle sensor technologies have led to an increased development and utilization of low-cost, compact, particulate matter (PM) monitors. These devices can be deployed in dense monitoring networks, enabling an improved characterization of the spatiotemporal variability in ambient levels and exposure. However, the reliability of their measurements is an important prerequisite, necessitating rigorous performance evaluation and calibration in comparison to reference-grade instrumentation. In this study, field evaluation of Purple Air PA-II devices (low-cost PM sensors) is performed in two urban environments and across three seasons in Greece, in comparison to different types of reference instruments. Measurements were conducted in Athens (the largest city in Greece with nearly four-million inhabitants) for five months spanning over the summer of 2019 and winter/spring of 2020 and in Ioannina, a medium-sized city in northwestern Greece (100,000 inhabitants) during winter/spring 2019–2020. The PM2.5 sensor output correlates strongly with reference measurements (R2 = 0.87 against a beta attenuation monitor and R2 = 0.98 against an optical reference-grade monitor). Deviations in the sensor-reference agreement are identified as mainly related to elevated coarse particle concentrations and high ambient relative humidity. Simple and multiple regression models are tested to compensate for these biases, drastically improving the sensor’s response. Large decreases in sensor error are observed after implementation of models, leading to mean absolute percentage errors of 0.18 and 0.12 for the Athens and Ioannina datasets, respectively. Overall, a quality-controlled and robustly evaluated low-cost network can be an integral component for air quality monitoring in a smart city. Case studies are presented along this line, where a network of PA-II devices is used to monitor the air quality deterioration during a peri-urban forest fire event affecting the area of Athens and during extreme wintertime smog events in Ioannina, related to wood burning for residential heating.

Long-term brown carbon spectral characteristics in a Mediterranean city (Athens)

This study analyses 4-years of continuous 7-λ Aethalometer (AE-33) measurements in an urban-background environment of Athens, to resolve the spectral absorption coefficients (b_abs) for black carbon (BC) and brown carbon (BrC). An important BrC contribution (23.7 ± 11.6%) to the total b_abs at 370 nm is estimated for the period May 2015-April 2019, characterized by a remarkable seasonality with winter maximum (33.5 ± 13.6%) and summer minimum (18.5 ± 8.1%), while at longer wavelengths the BrC contribution is significantly reduced (6.8 ± 3.6% at 660 nm). The wavelength dependence of the total b_abs gives an annual-mean AAE_370-880 of 1.31, with higher values in winter night-time. The BrC absorption and its contribution to b_abs presents a large increase reaching up to 39.1 ± 13.6% during winter nights (370 nm), suggesting residential wood burning (RWB) emissions as a dominant source for BrC. This is supported by strong correlations of the BrC absorption with OC, EC, the fragment ion m/z 60 derived from ACSM and PMF-analyzed organic fractions related to biomass burning (e.g. BBOA). In contrast, BrC absorption decreases significantly during daytime as well as in the warm period, reaching to a minimum during the early-afternoon hours in all seasons due to photo-chemical degradation. Estimated secondary BrC absorption is practically evident only during winter night-time, implying the fast oxidation of BrC species from RWB emissions. Changes in mixing-layer height do not significantly affect the BrC absorption in winter, while they play a major role in summer.

Comparison of fine particulate matter level, chemical content and oxidative potential derived from two dissimilar urban environments

Urban airborne particles contain a wide spectrum of components, known to have harmful effects on human health. This study reports a detailed investigation of fine particulate matter (PM_2.5), chemical content and oxidative potential derived from two different urban environments. During summer and winter, 20-day campaigns were conducted at Belgrade city center (urban-background site - UB) and Bor (urban-industrial site - UI). Using various analytical techniques, carbonaceous compounds, water-soluble inorganic ions, major and trace elements were determined, while the oxidative potential of PM_2.5 was estimated by dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay (OP^DCFH values). The mean PM_2.5 concentrations in both urban environments were above the recommended daily value, and the dominant PM_2.5 mass contributor was organic matter (29-55%). The OC/EC ratio was significantly higher at UB site during winter, which was an indication of a considerable contribution of secondary organic carbon to the overall organic carbon (OC). Water-soluble organic carbon (WSOC) was also higher at UB than at UI site, and it probably came from the same sources as OC. In general, the different partition of secondary organic aerosol (SOA) in warm and cold periods affected the number of organic components. Sulfates and nitrates were the most abundant ions at both sites and they counted approximately 40% (summer) and 50% (winter) of total ions. Further, the concentrations of the most elements, particularly some potentially carcinogenic elements such as As, Cd and Pb were significantly higher at UI, due to the emissions from the copper smelter complex in the vicinity. The mean OP^DCFH values were similar during the summer at both sampling sites, whereas a statistically significant difference between sites was noticed in favor of UB environment in winter.

Carbonaceous Aerosols in Contrasting Atmospheric Environments in Greek Cities: Evaluation of the EC-tracer Methods for Secondary Organic Carbon Estimation

This study examines the carbonaceous-aerosol characteristics at three contrasting urban environments in Greece (Ioannina, Athens, and Heraklion), on the basis of 12 h sampling during winter (January to February 2013), aiming to explore the inter-site differences in atmospheric composition and carbonaceous-aerosol characteristics and sources. The winter-average organic carbon (OC) and elemental carbon (EC) concentrations in Ioannina were found to be 28.50 and 4.33 µg m−3, respectively, much higher than those in Heraklion (3.86 µg m−3 for OC and 2.29 µg m−3 for EC) and Athens (7.63 µg m−3 for OC and 2.44 µg m−3 for EC). The winter OC/EC ratio in Ioannina (6.53) was found to be almost three times that in Heraklion (2.03), indicating a larger impact of wood combustion, especially during the night, whereas in Heraklion, emissions from biomass burning were found to be less intense. Estimations of primary and secondary organic carbon (POC and SOC) using the EC-tracer method, and specifically its minimum R-squared (MRS) variant, revealed large differences between the sites, with a prevalence of POC (67–80%) in Ioannina and Athens and with a larger SOC fraction (53%) in Heraklion. SOC estimates were also obtained using the 5% and 25% percentiles of the OC/EC data to determine the (OC/EC)pri, leading to results contrasting to the MRS approach in Ioannina (70–74% for SOC). Although the MRS method provides generally more robust results, it may significantly underestimate SOC levels in environments highly burdened by biomass burning, as the fast-oxidized semi-volatile OC associated with combustion sources is classified in POC. Further analysis in Athens revealed that the difference in SOC estimates between the 5% percentile and MRS methods coincided with the semi-volatile oxygenated organic aerosol as quantified by aerosol mass spectrometry. Finally, the OC/Kbb+ ratio was used as tracer for decomposition of the POC into fossil-fuel and biomass-burning components, indicating the prevalence of biomass-burning POC, especially in Ioannina (77%).

Chemical characterization, sources and potential health risk of PM2.5 and PM1 pollution across the Greater Athens Area

With the principal aim to assess the typical Mediterranean profile of the PM_2.5 and PM₁ pollution, three intensive monitoring campaigns took place simultaneously within different types of environment across an urban location of the basin. Focusing on the PM components with numerous anthropogenic sources and increased potential health risk, the samples were chemically analyzed for 20 p.m.-bound Polycyclic Aromatic Hydrocarbons (PAHs). Carbonaceous and ionic constituents were quantified as well. In order to uncover the spatiotemporal variation of the PM profile the key sources were identified, the seasonal effects and the role of the prevailing mesoscale atmospheric circulation were evaluated and most importantly the potential health risk was estimated. In general, the pollution status of the basin was the result of a complex interaction between the local and external input with Particulate Organic Matter (POM) and Secondary Inorganic Aerosols (SIA) being the main aerosols' components. PM₁ was a better indicator of the anthropogenic emissions while according to the results of factor analysis the co-existence of various combustion sources was determinant. Chemically, the maxima of the ΣPAHs, the differentiation of their structure in accordance with their molecular weight and the distribution of the individual compounds confirmed the significance of the emission sources. Similarly, the estimated carcinogenicity/mutagenicity was emission-dependent with the maximum contribution coming from B[a]P, IndP, B[ghi]Per, B[e]P and B[b]F. Seasonally, the highest potential health risk of the PAHs' mixture was recorded during the cold season while meteorologically, it was mostly associated with the south flow.

A Decade of Aerosol Optical Properties Measurements over Athens, Greece

Long-term ground-based measurements of aerosol optical properties in Athens, Greece, for the period 2008–2018 performed by the National Observatory of Athens are used in order to investigate the aerosol climatology of the area. In this study, we utilize quality-assured measurements of the aerosol optical depth (AOD), Single Scattering Albedo (SSA) and Ångström exponent obtained by CIMEL photometers in the framework of the Aerosol Robotic Network (AERONET) to extract the seasonality and the trends of aerosols in the region. Higher aerosol loads are found during spring and summer months. A 1.1% per year decrease for AOD at 440 nm and 0.4% decrease per year for SSA during the studied period are recorded. Collocated and synchronous PM10 values, for a five-year period, are used in order to study ground-level conditions. Also, the Planetary Boundary Layer Height from ERA-5 is used to investigate the stratification of the particles. The classification of aerosols using AERONET data is performed to separate dust, biomass burning, polluted urban, marine and continental dominant aerosol mixtures. Also, the characterization of AOD provided by Copernicus Atmosphere Monitoring Service (CAMS) is investigated. Finally, seasonal AOD trends recorded from AERONET from satellite sensors (MODIS-Aqua/MODIS-Terra) and estimated by CAMS are examined, and significant differences have been found.

Potential health and equity co-benefits related to the mitigation policies reducing air pollution from residential wood burning in Athens, Greece

Athens, Greece has been in economic and social crises after the 2008 global recession, resulting in an increase in wood burning as a cheaper method of residential heating in the winter. Reducing wood burning emissions is a source-specific method to address air quality degradation, and indirectly climate change, through instituting policies aimed at human health co-benefits. In this work, we investigate and quantify the potential health co-benefits from policies reducing outdoor particulate matter (PM) pollution from residential wood burning by assessing the pollution conditions during the 2015 calendar year in Athens, Greece, emphasizing vulnerable populations. We conducted a systematic literature search to extract data regarding effective improvements to outdoor PM due to wood burning interventions, and get a range of potential ambient PM reduction estimates regarding realistic benefits from different interventions. We applied a health impact assessment methodology and used existing Athens specific data to calculate the preventable daily average non-accidental deaths associated with reducing PM, additionally considering low and high socioeconomic status (SES) groups. We found that the reduction in outdoor PM concentration showed the potential to benefit lower SES groups as much as 13.5 times more than the high SES group, representing an opportunity for policies to improve not only the health of the total population but also improve environmental equity and health disparities.

Analysis of PM10 and PM2.5 Concentrations in an Urban Atmosphere in Northern Spain

This work analyses levels of particles PM10 and PM2.5 recorded at four air-quality monitoring stations located in the urban area of Valladolid (Spain) during 2015-2016. To achieve this, the evolution of particle concentrations at different time scales was determined. Average concentrations ranged from 15.3 to 17.6 µg m^-3 for PM10 and between 8.9 and 14.8 µg m^-3 for PM2.5. The highest monthly means were recorded in autumn and winter. The difference between mean concentrations at weekends and on weekdays for PM10 was around 3 µg m^-3 at most of the measuring stations and was 1 µg m^-3 for PM2.5. Two concentration peaks were found during the day, one in the morning and the other in the evening, which evidenced the influence of traffic and other anthropogenic activities on PM concentrations. Their mean values were approximately 21 and 17-21 µg m^-3, respectively, for PM10. Mean maximum values for PM2.5 were 12 µg m^-3, except at one of the measuring sites, with 17 µg m^-3 for the morning maximum and 1 µg m^-3 more for the nocturnal peak. In addition, the impact of long-distance transport of air masses in the study area was analysed by applying a HYSPLIT trajectory model, taking into account backward trajectories of European, African, and Atlantic origins as well as local conditions. In particular, high concentration events due to Saharan dust intrusions are presented. Finally, background levels of particle concentrations estimated at most sampling areas were around 15 and 7.7 µg m^-3 for the PM10 and PM2.5 particle fractions, respectively.

Using δ13C of Levoglucosan As a Chemical Clock

Compound specific carbon isotopic measurements (δ¹³C) of levoglucosan were carried out for ambient aerosol sampled during an intensive biomass burning period at different sites in Guangdong province, China. The δ¹³C of ambient levoglucosan was found to be noticeably heavier than the average δ¹³C of levoglucosan found in source C3-plant-combustion samples. To estimate the photochemical age of sampled ambient levoglucosan, back trajectory analyses were done. The origin and pathways of the probed air masses were determined, using the Lagrangian-particle-dispersion-model FLEXPART and ECMWF meteorological data. On the other hand, the isotopic hydrocarbon clock concept was applied to relate the changes in the field-measured stable carbon isotopic composition to the extent of chemical processing during transport. Comparison of the photochemical age derived using these two independent approaches shows on average good agreement, despite a substantial scatter of the individual data pairs. These analyses demonstrate that the degree of oxidative aging of particulate levoglucosan can be quantified by combining laboratory KIE studies, observed δ¹³C at the source and in the field, as well as back trajectory analyses. In this study, the chemical loss of levoglucosan was found to exceed 50% in one-fifth of the analyzed samples. Consequently, the use of levoglucosan as a stable molecular tracer may underestimate the contribution of biomass burning to air pollution.

Has the risk of mortality related to short-term exposure to particles changed over the past years in Athens, Greece?

Although the health effects of short-term exposure to ambient particles have been well documented, there is a need to update scientific knowledge due to the continuously changing profile of the air pollution mixture. Furthermore the effect of the severe economic crisis in Greece that started in 2008 on previously reported associations has not been studied. We assessed the change in mortality risk associated with short-term exposure to PM₁₀ in Athens, Greece during 2001-12. Time-series data on the daily concentrations of regulated particles and all cause, cardiovascular and respiratory mortality were analyzed using overdispersed Poisson regression models, controlling for time-varying confounders such as seasonality, meteorology, influenza outbreaks, summer holidays and day of the week. We assessed changes in risk over time by inclusion of an interaction term between particles' levels and time or predefined periods, i.e. 2001-07 and 2008-12. While the related mortality risks increased over the analyzed period, the difference before and after 2008 was significant only for total mortality (p-value for interaction .03) and driven by the difference observed among those ≥75 years. An interquartile increase in PM₁₀ before 2008 was associated with 1.51% increase in deaths among ≥75 years (95% Confidence interval (CI): 0.62%, 2.40%), while after 2008 with a 2.61% increase (95%CI: 1.72%, 3.51%) (p-value for interaction .01). Our results indicate that despite the decline in particles' concentration in Athens, Greece during 2001-12 the associated mortality risk has possibly increased, suggesting that the economic crisis initiated in 2008 may have led to changes in the particles' composition due to the ageing of the vehicular fleet and the increase in the use of biomass fuel for heating.

Impact of the financial crisis on COPD burden: Greece as a case study

Poverty and low socioeconomic status have been associated with chronic obstructive pulmonary disease (COPD). The current financial crisis has forced millions back into poverty. Greece is one of the countries hit the hardest, and is in the middle of a deep ongoing collapse. There have been early reports stating the apparent effects of the Greek downturn on respiratory health. This review summarises the overall impact of the financial crisis on COPD burden throughout the period of economic downturn by analysing the case study of Greece. In all levels of the healthcare system, current economic restrictions have reduced the capacity to prevent, diagnose and treat COPD in parallel with current higher detection rates of COPD. Remarkably, expenditure on healthcare has been reduced by >25%, resulting in major healthcare equipment shortages. Lower wages (by up to 20%) and higher co-payments of up to 25% of a drug's purchase price have led to patients struggling to afford inhaled medications. Treatment nonadherence has been reported, resulting in 11.5% more exacerbations and 14.1% more hospitalisations annually, while the mean cost per severe COPD exacerbation has been approximated as €2600. Greece is a noteworthy example illustrating how COPD burden, quality of care and patients' outcome can be affected by economic crisis.

Fate, Transformation, and Toxicological Impacts of Pharmaceutical and Personal Care Products in Surface Waters

With the growth of the human population, a greater quantity of pharmaceutical and personal care products (PPCPs) have been released into the environment. Although research has addressed the levels and the impact of PPCPs in the environment, the fate of these compounds in surface waters is neither well known nor characterized. In the environment, PPCPs can undergo various transformations that are critically dependent on environmental factors such as solar radiation and the presence of soil particles. Given that the degradation products of PPCPs are poorly characterized, these "secondary residues" can be a significant environmental health hazard due to their drastically different toxicologic effects when compared with the parent compounds. To better understand the fate of PPCPs, we studied the degradation of selected PPCPs, including ibuprofen and clofibric acid, in aqueous solutions that contained kaolinite clay and were irradiated with a solar simulator. The most abundant degradation products were identified and assessed for their toxicologic impact on selected microorganisms. The degraded mixtures showed lower toxicity than the starting compounds; however, as these degradation products are capable of further transformation and interaction with other PPCPs in natural waters, our work highlights the importance of additionally characterizing the PPCP degradation products.

Chemical composition, source, and process of urban aerosols during winter haze formation in Northeast China

The characteristics of aerosol particles have been poorly evaluated even though haze episodes frequently occur in winter in Northeast China. OC/EC analysis, ion chromatography, and transmission electron microscopy (TEM) were used to investigate the organic carbon (OC) and elemental carbon (EC), and soluble ions in PM_2.5 and the mixing state of individual particles during a severe wintertime haze episode in Northeast China. The organic matter (OM), NH₄⁺, SO₄^2-, and NO₃^- concentrations in PM_2.5 were 89.5 μg/m³, 24.2 μg/m³, 28.1 μg/m³, and 32.8 μg/m³ on the haze days, respectively. TEM observations further showed that over 80% of the haze particles contained primary organic aerosols (POAs). Based on a comparison of the data obtained during the haze formation, we generate the following synthetic model of the process: (1) Stable synoptic meteorological conditions drove the haze formation. (2) The early stage of haze formation (light or moderate haze) was mainly caused by the enrichment of POAs from coal burning for household heating and cooking. (3) High levels of secondary organic aerosols (SOAs), sulfates, and nitrates formation via heterogeneous reactions together with POAs accumulation promoted to the evolution from light or moderate to severe haze. Compared to the severe haze episodes over the North China Plain, the PM_2.5 in Northeast China analyzed in the present study contained similar sulfate, higher SOA, and lower nitrate contents. Our results suggest that most of the POAs and secondary particles were likely related to emissions from coal-burning residential stoves in rural outskirts and small boilers in urban areas. The inefficient burning of coal for household heating and cooking should be monitored during wintertime in Northeast China.

The combined effect of reduced fossil fuel consumption and increasing biomass combustion on Athens' air quality, as inferred from long term CO measurements

To evaluate the role of biomass burning emissions, and in particular of residential wood heating, as a result of the economic recession in Greece, carbon monoxide (CO) atmospheric concentrations from five (5) stations of the National Air Pollution Monitoring Network in Athens, spanning the period 2000-2015, in conjunction with black carbon (BC) concentrations from the NOA (National Observatory of Athens) station at Thissio were analysed. The contribution of the different sources to the diurnal cycle of these two pollutants is clear, resulting to a morning peak, mainly due to traffic, and a late evening peak attributed both to fossil fuel (traffic plus central heating) and biomass combustion. Calculated morning and evening integrals of CO peaks, for the investigated period, show consistent seasonal modulations, characterised by low summer and high winter values. The summer and winter morning CO peak integrals demonstrate an almost constant decreasing trend of CO concentrations over time (by almost 50% since 2000), attributed to the renewal of passenger car fleet and to reduced anthropogenic activities during the last years. On the other hand, an increase of 23%-78% (depending on the monitoring site) in the winter evening integrals since 2012, provides evidence of the significant contribution of biomass combustion, which has prevailed over fossil fuel for domestic heating. CO emitted by wood burning was found to contribute almost 50% to the total CO emissions during night time (16:00-5:00), suggesting that emissions from biomass combustion have gained an increasing role in atmospheric pollution levels in Athens.

Medium-term impact of the economic crisis on mortality, health-related behaviours and access to healthcare in Greece

Previous studies on the health consequences of the crisis in Greece investigated short-term impacts on selected outcomes. This study examined the impact of the crisis on a key set of health indicators with longer follow up than previous studies. We conducted interrupted time series (ITS) analysis to compare trends in standardised mortality by cause before and during the crisis. We examined changes in fruit and vegetable consumption, smoking, physical activity, obesity, out-of-pocket payments and unmet needs for healthcare using national household data from the “Hellas Health” surveys. Standardised mortality rates for suicides (p < 0.001) and infant mortality (p = 0.003) increased during the crisis compared to pre-existing trends, while mortality from respiratory diseases (p = 0.053) and transport accidents (p = 0.067) decreased. The prevalence of smoking (42.6% to 36.5%; RR = 0.86) and sedentary lifestyle (43.4% to 29.0%; RR = 0.69) declined. The prevalence of unmet need for healthcare significantly increased from 10.0% to 21.9% (RR = 2.10) and the proportion of people paying out-of-pocket for healthcare from 34.4% to 58.7% (RR = 1.69) between 2010 and 2015. The impact of the economic crisis in Greece on health was more nuanced than previous reports suggest. Effective strategies to mitigate the adverse health impacts of economic crises need to be better understood and implemented.

Spatial and temporal variability of carbonaceous aerosols: Assessing the impact of biomass burning in the urban environment

Biomass burning (BB) is a significant source of atmospheric particles in many parts of the world. Whereas many studies have demonstrated the importance of BB emissions in central and northern Europe, especially in rural areas, its impact in urban air quality of southern European countries has been sparsely investigated. In this study, highly time resolved multi-wavelength absorption coefficients together with levoglucosan (BB tracer) mass concentrations were combined to apportion carbonaceous aerosol sources. The Aethalometer model takes advantage of the different spectral behavior of BB and fossil fuel (FF) combustion aerosols. The model was found to be more sensitive to the assumed value of the aerosol Ångström exponent (AAE) for FF (AAE_ff) than to the AAE for BB (AAE_bb). As result of various sensitivity tests the model was optimized with AAE_ff=1.1 and AAE_bb=2. The Aethalometer model and levoglucosan tracer estimates were in good agreement. The Aethalometer model was further applied to data from three sites in Granada urban area to evaluate the spatial variation of CM_ff and CM_bb (carbonaceous matter from FF or BB origin, respectively) concentrations within the city. The results showed that CM_bb was lower in the city centre while it has an unexpected profound impact on the CM levels measured in the suburbs (about 40%). Analysis of BB tracers with respect to wind speed suggested that BB was dominated by sources outside the city, to the west in a rural area. Distinguishing whether it corresponds to agricultural waste burning or with biomass burning for domestic heating was not possible. This study also shows that although traffic restrictions measures contribute to reduce carbonaceous concentrations, the extent of the reduction is very local. Other sources such as BB, which can contribute to CM as much as traffic emissions, should be targeted to reduce air pollution.

Seasonal characteristics of water-soluble inorganic ions and carbonaceous aerosols in total suspended particulate matter at a rural semi-arid site, Kadapa (India)

To better understand the sources as well as characterization of regional aerosols at a rural semi-arid region Kadapa (India), size-resolved composition of atmospheric particulate matter (PM) mass concentrations was sampled and analysed. This was carried out by using the Anderson low-pressure impactor for a period of 2 years during March 2013-February 2015. Also, the variations of organic carbon (OC), elemental carbon (EC) and water-soluble inorganic ion components (WSICs) present in total suspended particulate matter (TSPM) were studied over the measurement site. From the statistical analysis, the PM mass concentration showed a higher abundance of coarse mode particles than the fine mode during pre-monsoon season. In contrast, fine mode particles in the PM concentration showed dominance over coarse mode particle contribution during the winter. During the post-monsoon season, the percentage contributions of coarse and fine fractions were equal, whereas during the monsoon, coarse mode fraction was approximately 26 % higher than the fine mode. This distinct feature in the case of fine mode particles during the studied period is mainly attributed to large-scale anthropogenic activities and regional prevailing meteorological conditions. Further, the potential sources of PM have been identified qualitatively by using the ratios of certain ions. A high sulphate (SO₄) concentration at the measurement site was observed during the studied period which is caused by the nearby/surrounding mining activity. Carbon fractions (OC and EC) were also analysed from the TSPM, and the results indicated (OC/EC ratio of ~4.2) the formation of a secondary organic aerosol. At last, the cluster backward trajectory analyses were also performed at Kadapa for different seasons to reveal the origin of sources from long-range transport during the study period.

Enrichment factors to assess the anthropogenic influence on PM10 in Gijón (Spain)

Thirty-two chemical species were determined in PM₁₀ sampled at a suburban site on the north coast of Spain. Enrichment factors were applied to infer their soil/non-soil origin. The geochemical ratios were calculated using two databases: soil composition from locations in the surroundings of the sampling station and the Earth's average upper-crust composition. In the present study, dissimilarities were found between the enrichment factors obtained using these two databases. Al, Ti, La and Ce were taken as the reference elements to normalise the data, reaching analogous conclusions. Bi, Cd, Cu, Sb, Se, Sn and Zn were associated with predominantly non-soil apportionments. As the relevance of soil/non-soil sources for the other analysed elements was found to be variable, they were probably of mixed origin. Furthermore, pairs of elements showed strong relationships, thus pointing to a common origin. Na-Mg and Co-Ni, with Pearson correlation coefficients above 0.9, were respectively related to marine and industrial apportionments. Enrichment factors have proved to be a useful tool to distinguish the soil/non-soil origin of chemical species present in airborne particulate matter. However, the choice of the reference database for soil composition considerably determined the accuracy of the conclusions.

Wintertime chemical compositions of coarse and fine fractions of particulate matter in Bolu, Turkey

Coarse (particulate matter (PM)2.5-10) and fine (PM2.5) fraction of PM samples were collected between December 2014 and February 2015 at an urban sampling site located at the Bolu plain, of the western Black Sea region of Turkey. The collected samples were analyzed in terms of metals (Al, As, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Pb, S, Si, Ti, V, and Zn); elemental carbon (EC); and organic carbon (OC). Elevated concentrations measured in this wintertime study were ∼7.8 μg/m(3) in sum of PM2.5-10 and PM2.5 for SO4 (2-) and ∼59.9 μg/m(3) in PM2.5 for OC. The contributions of primary and secondary OC (POC and SOC, respectively) to total OC mass were 60 and 40 %, respectively, while contribution of SOC to OC increased by up to 74 % in stable atmospheric conditions. The significantly high OC/EC ratio (∼10.1) found in this study relative to other wintertime studies was attributed to increased emissions from residential heating and lower mixing height observed during the study. Two and three factors were resolved by factor analysis for PM2.5-10 and PM2.5, respectively. Two Saharan dust episodes were observed on 31 January and 1 February, during which crustal PM components such as Mg, Si, and Al increased as much as three times their background concentrations.

Seasonal and regional variations of source contributions for PM10 and PM2.5 in urban environment

To characterize the sources of to PM10 and PM2.5, a long-term, speciate and simultaneous dataset was sampled in a megacity in China during the period of 2006-2014. The PM concentrations and PM2.5/PM10 were higher in the winter. Higher percentages of Al, Si, Ca and Fe were observed in the summer, and higher concentrations of OC, NO3(-) and SO4(2-) occurred in the winter. Then, the sources were quantified by an advanced three-way model (defined as an ABB three-way model), which estimates different profiles for different sizes. A higher percentage of cement and crustal dust was present in the summer; higher fractions of coal combustion and nitrate+SOC were observed in the winter. Crustal and cement contributed larger portion to coarse part of PM10, whereas vehicular and secondary source categories were enriched in PM2.5. Finally, potential source contribution function (PSCF) and source regional apportionment (SRA) methods were combined with the three-way model to estimate geographical origins. During the sampling period, the southeast region (R4) was an important region for most source categories (0.6%-11.5%); the R1 (centre region) also played a vital role (0.3-6.9%).