Search

Providing reliable observations of aerosol particles' absorption properties at spatial and temporal resolutions suited to climate models is of utter importance to better understand the effects that atmospheric particles have on climate. Nowadays, one of the instruments most widely used in international monitoring networks for in situ surface measurements of light absorption properties of atmospheric aerosol particles is the multi-wavelength dual-spot Aethalometer, AE33. The AE33 derives the absorption coefficients of aerosol particles at seven different wavelengths from the measurements of the optical attenuation of light through a filter where particles are continuously collected. An accurate determination of the absorption coefficients from the AE33 instrument relies on the quantification of the non-linear processes related to the sample collection on the filter. The multiple-scattering correction factor (C), which depends on the filter tape used and on the optical properties of the collected particles, is the parameter with both the greatest uncertainty and the greatest impact on the absorption coefficients derived from the AE33 measurements. Here we present an in-depth analysis of the AE33 multiple-scattering correction factor C and its wavelength dependence for two different and widely used filter tapes, namely the old, and most referenced, TFE-coated glass, or M8020, filter tape and the currently, and most widely used, M8060 filter tape. For performing this analysis, we compared the attenuation measurements from AE33 with the absorption coefficients measured with different filter-based techniques. On-line co-located multi-angle absorption photometer (MAAP) measurements and off-line PP_UniMI polar photometer measurements were employed as reference absorption measurements for this work. To this aim, we used data from three different measurement stations located in the north-east of Spain, namely an urban background station (Barcelona, BCN), a regional background station (Montseny, MSY) and a mountaintop station (Montsec d'Ares, MSA). The median C values (at 637 nm) measured at the three stations ranged between 2.29 (at BCN and MSY, lowest 5th percentile of 1.97 and highest 95th percentile of 2.68) and 2.51 (at MSA, lowest 5th percentile of 2.06 and highest 95th percentile of 3.06). The analysis of the cross-sensitivity to scattering, for the two filter tapes considered here, revealed a large increase in the C factor when the single-scattering albedo (SSA) of the collected particles was above a given threshold, up to a 3-fold increase above the average C values. The SSA threshold appeared to be site dependent and ranged between 0.90 to 0.95 for the stations considered in the study. The results of the cross-sensitivity to scattering displayed a fitted constant multiple-scattering parameter, Cf , of 2.21 and 1.96, and a cross-sensitivity factor, ms , of 1.8 % and 3.4 % for the MSY and MSA stations, respectively, for the TFE-coated glass filter tape. For the M8060 filter tape, Cf values of 2.50, 1.96 and 1.82 and ms values of 1.6 %, 3.0 % and 4.9 % for the BCN, MSY and MSA stations, respectively, were obtained. SSA variations also influenced the spectral dependence of C , which showed an increase with wavelength when SSA was above the site-dependent threshold. Below the SSA threshold, no statistically significant dependence of C on the wavelength was observed. For the measurement stations considered here, the wavelength dependence of C was to some extent driven by the presence of dust particles during Saharan dust outbreaks that had the potential to increase the SSA above the average values. At the mountaintop station, an omission of the wavelength dependence of the C factor led to an underestimation of the absorption Ångström exponent (AAE) by up to 12 %. Differences in the absorption coefficient determined from AE33 measurements at BCN, MSY and MSA of around 35 %–40 % can be expected when using the site-dependent experimentally obtained C value instead of the nominal C value. Due to the fundamental role that the SSA of the particles collected on the filter tape has in the multiple-scattering parameter C , we present a methodology that allows the recognition of the conditions upon which the use of a constant and wavelength-independent C is feasible. [ABSTRACT FROM AUTHOR]

Accurate measurements of the horizontal and vertical distribution of atmospheric aerosol particle optical properties are key for a better understanding of their impact on the climate. Here we present the results of a measurement campaign based on instrumented flights over north-eastern Spain. We measured vertical profiles of size-segregated atmospheric particulate matter (PM) mass concentrations and multi-wavelength scattering and absorption coefficients in the western Mediterranean basin (WMB). The campaign took place during typical summer conditions, characterized by the development of a vertical multi-layer structure, under both summer regional pollution episodes (REGs) and Saharan dust events (SDEs). REG patterns in the region form under high insolation and scarce precipitation in summer, favouring layering of highly aged fine-PM strata in the lower few kma.s.l. The REG scenario prevailed during the entire measurement campaign. Additionally, African dust outbreaks and plumes from northern African wildfires influenced the study area. The vertical profiles of climate-relevant intensive optical parameters such as single-scattering albedo (SSA); the asymmetry parameter (g); scattering, absorption and SSA Ångström exponents (SAE, AAE and SSAAE); and PM mass scattering and absorption cross sections (MSC and MAC) were derived from the measurements. Moreover, we compared the aircraft measurements with those performed at two GAW–ACTRIS (Global Atmosphere Watch–Aerosol, Clouds and Trace Gases) surface measurement stations located in north-eastern Spain, namely Montseny (MSY; regional background) and Montsec d'Ares (MSA; remote site). Airborne in situ measurements and ceilometer ground-based remote measurements identified aerosol air masses at altitudes up to more than 3.5 kma.s.l. The vertical profiles of the optical properties markedly changed according to the prevailing atmospheric scenarios. During SDE the SAE was low along the profiles, reaching values < 1.0 in the dust layers. Correspondingly, SSAAE was negative, and AAE reached values up to 2.0–2.5, as a consequence of the UV absorption increased by the presence of the coarse dust particles. During REG, the SAE increased to > 2.0, and the asymmetry parameter g was rather low (0.5–0.6) due to the prevalence of fine PM, which was characterized by an AAE close to 1.0, suggesting a fossil fuel combustion origin. During REG, some of the layers featured larger AAE (> 1.5), relatively low SSA at 525 nm (< 0.85) and high MSC (> 9 m2g-1) and were associated with the influence of PM from wildfires. Overall, the SSA and MSC near the ground ranged around 0.85 and 3 m2g-1 , respectively, and increased at higher altitudes, reaching values above 0.95 and up to 9 m2g-1. The PM, MSC and MAC were on average larger during REG compared to SDE due to the larger scattering and absorption efficiency of fine PM compared with dust. The SSA and MSC had quite similar vertical profiles and often both increased with height indicating the progressive shift toward PM with a larger scattering efficiency with altitude. This study contributes to our understanding of regional-aerosol vertical distribution and optical properties in the WMB, and the results will be useful for improving future climate projections and remote sensing or satellite retrieval algorithms. [ABSTRACT FROM AUTHOR]

Atmospheric aerosols contribute some of the greatest uncertainties to estimates of global radiative forcing and have significant effects on human health. New particle formation (NPF) is the process by which new aerosols of sub-2 nm diameter form from gas-phase precursors and contributes significantly to particle numbers in the atmosphere, accounting for approximately 50 % of cloud condensation nuclei globally. Here, we study summertime NPF in urban Barcelona in north-eastern Spain utilising particle counting instruments down to 1.9 nm and a Nitrate Chemical Ionisation Atmospheric Pressure interface Time of Flight Mass Spectrometer (CI-APi-ToF). The rate of formation of new particles is seen to increase linearly with sulfuric acid concentration, although particle formation rates fall short of chamber studies of H2SO4 –DMA– H2O while exceeding those of H2SO4 –BioOxOrg– H2O nucleation, although a role of highly oxygenated molecules (HOMs) cannot be ruled out. The sulfuric acid dimer : monomer ratio is significantly lower than that seen in experiments involving sulfuric acid and dimethylamine (DMA) in chambers, indicating that stabilisation of sulfuric acid clusters by bases is weaker in this dataset than in chambers, either due to rapid evaporation due to high summertime temperatures or limited pools of stabilising amines. Such a mechanism cannot be verified in these data, as no higher-order H2SO4 –amine clusters nor H2SO4 –HOM clusters were measured. The high concentrations of HOMs arise from isoprene, alkylbenzene, monoterpene and polycyclic aromatic hydrocarbon (PAH) oxidation, with alkylbenzenes providing greater concentrations of HOMs due to significant local sources. The concentration of these HOMs shows a dependence on temperature. The organic compounds measured primarily fall into the semivolatile organic compound (SVOC) volatility class arising from alkylbenzene and isoprene oxidation. Low-volatility organic compounds (LVOCs) largely arise from oxidation of alkylbenzenes, PAHs and monoterpenes, whereas extremely low-volatility organic compounds (ELVOCs) arise from primarily PAH and monoterpene oxidation. New particle formation without growth past 10 nm is also observed, and on these days oxygenated organic concentrations are lower than on days with growth by a factor of 1.6, and thus high concentrations of low-volatility oxygenated organics which primarily derive from traffic-emitted volatile organic compounds (VOCs) appear to be a necessary condition for the growth of newly formed particles in Barcelona. These results are consistent with prior observations of new particle formation from sulfuric acid–amine reactions in both chambers and the real atmosphere and are likely representative of the urban background of many European Mediterranean cities. A role for HOMs in the nucleation process cannot be confirmed or ruled out, and there is strong circumstantial evidence of the participation of HOMs across multiple volatility classes in particle growth. [ABSTRACT FROM AUTHOR]

There is limited suggestive evidence of relationships between public transport strikes and either increased air pollution or worse population health. In this study we aimed to assess whether public transport strikes were associated with increases in health events (overall, cardiovascular and respiratory mortality, and cardiovascular and respiratory hospitalizations). We also explored whether air pollution mediated those associations. We used data from the city of Barcelona (Spain) for the period 2005–2016 on strikes, health events, and ambient air pollution (nitrogen dioxide, nitrogen monoxide, particulate matter (PM) with an aerodynamic diameter ≤10 μm, PM with an aerodynamic diameter ≤2.5μm, PM with an aerodynamic diameter ≤1μm, number of particles with a diameter greater than 5 nm per cm3 (particle number concentration), and black carbon). We used linear and quasi-Poisson regression models to explore the associations between air pollution and public transport strikes and between public transport strikes and health outcomes. We also investigated potential causal mediation by air pollution. Overall, this study suggested that public transport strikes are associated with increased overall mortality, respiratory mortality, and respiratory hospitalizations. However, our findings suggest that such increases are not mediated by the increase in air pollution. Our results indicate the need to further investigate these relationships and potential mechanisms. [ABSTRACT FROM AUTHOR]

It is well established that in Europe, high O3 concentrations are most pronounced in southern/Mediterranean countries due to the more favourable climatological conditions for its formation. However, the contribution of the different sources of precursors to O3 formation within each country relative to the imported (regional and hemispheric) O3 is poorly quantified. This lack of quantitative knowledge prevents local authorities from effectively designing plans that reduce the exceedances of the O3 target value set by the European air quality directive. O3 source attribution is a challenge because the concentration at each location and time results not only from local biogenic and anthropogenic precursors, but also from the transport of O3 and precursors from neighbouring regions, O3 regional and hemispheric transport and stratospheric O3 injections. The main goal of this study is to provide a first quantitative estimation of the contribution of the main anthropogenic activity sectors to peak O3 events in Spain relative to the contribution of imported (regional and hemispheric) O3. We also assess the potential of our source apportionment method to improve O3 modelling. Our study applies and thoroughly evaluates a countrywide O3 source apportionment method implemented in the CALIOPE air quality forecast system for Spain at high resolution (4 × 4 km 2) over a 10-day period characterized by typical summer conditions in the Iberian Peninsula (IP). The method tags both O3 and its gas precursor emissions from source sectors within one simulation, and each tagged species is subject to the typical physico-chemical processes (advection, vertical mixing, deposition, emission and chemistry) as the actual conditions remain unperturbed. We quantify the individual contributions of the largest NOx local sources to high O3 concentrations compared with the contribution of imported O3. We show, for the first time, that imported O3 is the largest input to the ground-level O3 concentration in the IP, accounting for 46 %–68 % of the daily mean O3 concentration during exceedances of the European target value. The hourly imported O3 increases during typical northwestern advections (70 %–90 %, 60–80 µ g m -3), and decreases during typical stagnant conditions (30 %–40 %, 30–60 µ g m -3) due to the local NO titration. During stagnant conditions, the local anthropogenic precursors control the O3 peaks in areas downwind of the main urban and industrial regions (up to 40 % in hourly peaks). We also show that ground-level O3 concentrations are strongly affected by vertical mixing of O3 -rich layers present in the free troposphere, which result from local/regional layering and accumulation, and continental/hemispheric transport. Indeed, vertical mixing largely explains the presence of imported O3 at ground level in the IP. Our results demonstrate the need for detailed quantification of the local and remote contributions to high O3 concentrations for local O3 management, and show O3 source apportionment to be an essential analysis prior to the design of O3 mitigation plans in any non-attainment area. Achieving the European O3 objectives in southern Europe requires not only ad hoc local actions but also decided national and European-wide strategies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Traffic-related air pollution is emerging as a risk factor for Alzheimer's disease (AD) and impaired brain development. Individual differences in vulnerability to air pollution may involve the ∊4 allele of Apolipoprotein E (APOE) gene, the primary genetic risk factor for AD. OBJECTIVE: We analyzed whether the association between traffic air pollution and neurodevelopmental outcomes is modified by APOE ∊4 status in children. METHODS: Data on parent-reported behavior problems (total difficulties scores, Strengths and Difficulties Questionnaire), teacher-reported attentiondeficit hyperactivity disorder (ADHD) symptom scores, cognitive performance trajectories (computerized tests of inattentiveness and working memory repeated 2-4 times during January 2012-March 2013), and APOE genotypes were obtained for 1,667 children age 7-11 y attending 39 schools in or near Barcelona. Basal ganglia volume (putamen, caudate, and globus pallidum) was measured in 163 of the children by MRI (October 2012-April 2014.) Average annual outdoor polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), and nitrogen dioxide (NO2 concentrations were estimated based on measurements at each school (two 1-wk campaigns conducted 6 months apart in 2012). RESULTS: APOE ∊4 allele carriers had significantly higher behavior problem scores than noncarriers, and adverse associations with PAHs and NO2 were stronger or limited to ∊4 carriers for behavior problem scores (P-interaction 0.03 and 0.04), caudate volume (P-interaction 0.04 and 0.03), and inattentiveness trajectories (P-interaction 0.15 and 0.08, respectively). Patterns of associations with the same outcomes were similar for EC. CONCLUSION: PAHs, EC, and NO2 were associated with higher behavior problem scores, smaller reductions in inattentiveness over time, and smaller caudate volume in APOE ∊4 allele carriers in our study population, and corresponding associations were weak or absent among ∊4 noncarriers. These findings support a potential role of APOE in biological mechanisms that may contribute to associations between air pollution and neurobehavioral outcomes in children. [ABSTRACT FROM AUTHOR]

BACKGROUND: A few studies have reported associations between traffic-related air pollution exposure at schools and cognitive development. The role of PM components or sources other than traffic on cognitive development has been little explored. OBJECTIVES: We aimed to explore the role of PM sources in school air on cognitive development. METHODS: A cohort of 2,618 schoolchildren (average age, 8.5 years) belonging to 39 schools in Barcelona (Spain) was followed up for a year. Children completed computerized tests assessing working memory, superior working memory, and inattentiveness during four visits. Particulate matter ≤ 2.5 μm (PM[sub 2.5]) was measured during two 1-week campaigns in each school, both outdoors and in the classroom. Source apportionment resulted in nine sources: mineral, organic/textile/chalk, traffic, secondary sulfate and organics, secondary nitrate, road dust, metallurgy, sea spray, and heavy oil combustion. Differences in cognitive growth trajectories were assessed with mixed models with age-by-source interaction terms. RESULTS: An interquartile range increase in indoor traffic-related PM2 5 was associated with reductions in cognitive growth equivalent to 22% (95% CI: 2%, 42%) of the annual change in working memory, 30% (95% CI: 6%, 54%) of the annual change in superior working memory, and 11% (95% CI: 0%, 22%) of the annual change in the inattentiveness scale. None of the other PM[sub 2.5] sources was associated with adverse effects on cognitive development. CONCLUSIONS: Traffic was the only source of fine particles associated with a reduction in cognitive development. Reducing air pollution from traffic at primary schools may result in beneficial effects on cognition. CITATION: Basagafia X, Esnaola M, Rivas I, Amato F, Alvarez-Pedrerol M, Forns J, Lôpez-Vicente M, Pujol J, Nieuwenhuijsen M, Querol X, Sunyer J. 2016. Neurodevelopmental deceleration by urban fine particles from different emission sources: a longitudinal observational study. Environ Health Perspect 124:1630-1636; http://dx.doi.org/10.1289/EHP209 [ABSTRACT FROM AUTHOR]

In this work for the first time data from two twin stations (Barcelona, urban background, and Montseny, regional background), located in the northeast (NE) of Spain, were used to study the trends of the concentrations of different chemical species in PM10 and PM2.5 along with the trends of the PM10 source contributions from the positive matrix factorization (PMF) model. Eleven years of chemical data (2004-2014) were used for this study. Trends of both species concentrations and source contributions were studied using the Mann-Kendall test for linear trends and a new approach based on multi-exponential fit of the data. Despite the fact that different PM fractions (PM2.5, PM10/ showed linear decreasing trends at both stations, the contributions of specific sources of pollutants and of their chemical tracers showed exponential decreasing trends. The different types of trends observed reflected the different effectiveness and/or time of implementation of the measures taken to reduce the concentrations of atmospheric pollutants. Moreover, the trends of the contributions of specific sources such as those related with industrial activities and with primary energy consumption mirrored the effect of the financial crisis in Spain from 2008. The sources that showed statistically significant downward trends at both Barcelona (BCN) and Montseny (MSY) during 2004-2014 were secondary sulfate, secondary nitrate, and V-Ni-bearing source. The contributions from these sources decreased exponentially during the considered period, indicating that the observed reductions were not gradual and consistent over time. Conversely, the trends were less steep at the end of the period compared to the beginning, thus likely indicating the attainment of a lower limit. Moreover, statistically significant decreasing trends were observed for the contributions to PM from the industrial/traffic source at MSY (mixed metallurgy and road traffic) and from the industrial (metallurgy mainly) source at BCN. These sources were clearly linked with anthropogenic activities, and the observed decreasing trends confirmed the effectiveness of pollution control measures implemented at European or regional/local levels. Conversely, at regional level, the contributions from sources mostly linked with natural processes, such as aged marine and aged organics, did not show statistically significant trends. The trends observed for the PM10 source contributions reflected the trends observed for the chemical tracers of these pollutant sources well. [ABSTRACT FROM AUTHOR]

BACKGROUND: The available evidence of the effects of air pollution and noise on behavioral development is limited, and it overlooks exposure at schools, where children spend a considerable amount of time. OBJECTIVE: We aimed to investigate the associations of exposure to traffic-related air pollutants (TRAPs) and noise at school on behavioral development of schoolchildren. METHODS: We evaluated children 7-11 years of age in Barcelona (Catalonia, Spain) during 2012-2013 within the BREATHE project. Indoor and outdoor concentrations of elemental carbon (EC), black carbon (BC), and nitrogen dioxide (NO[sub 2]) were measured at schools in two separate 1-week campaigns. In one campaign we also measured noise levels inside classrooms. Parents filled out the strengths and difficulties questionnaire (SDQ) to assess child behavioral development, while teachers completed the attention deficit/hyperactivity disorder criteria of the DSM-IV (ADHD-DSM-IV) list to assess specific ADHD symptomatology. Negative binomial mixed-effects models were used to estimate associations between the exposures and behavioral development scores. RESULTS: Interquartile range (IQR) increases in indoor and outdoor EC, BC, and NO2 concentrations were positively associated with SDQ total difficulties scores (suggesting more frequent behavioral problems) in adjusted multivariate models, whereas noise was significantly associated with ADHD-DSM-IV scores. CONCLUSION: In our study population of 7- to 11-year-old children residing in Barcelona, exposure to TRAPs at school was associated with increased behavioral problems in schoolchildren. Noise exposure at school was associated with more ADHD symptoms. [ABSTRACT FROM AUTHOR]

Measurements of CO 2 and counting of occupants were carried out in 37 public bus trips during commuting rush hours in Barcelona (NE Spain) with the aim of evaluating parameters governing ventilation inside the vehicles and proposing actions to improve it. The results show that CO 2 concentrations (1039 and 934 ± 386 ppm, as average and median, during rush hours but with average reduced occupancy due to the fair to be infected by SARS-CoV-2 during the measurement period, and measured in the middle of the busses) are in the lower range of values recorded in the literature for public buses, however an improvement in ventilation is required in a significant proportion of the journeys. Thus, we found better ventilation in the older Euro 3+ (retrofitted with filter traps and selective catalytic reduction) and Euro 5 buses (average 918 ± 257 ppm) than in the hermetically closed new Euro 6 ones (1111 ± 432 ppm). The opening of the windows in the older buses yielded higher ventilation rates (778 ± 432 ppm). The opening of all doors at all stops increases the ventilation by causing a fall in concentrations of 200–350 ppm below inter-stop concentrations, with this effect typically lasting 40–50 s in the hermetically closed new Euro 6 hybrid buses. Based on these results a number of recommendations are offered in order to improve ventilation, including measurement of CO 2 and occupancy, and installation of ventilation fans on the top of the hermetically closed new buses, introducing outdoor air when a given concentration threshold is exceeded. In these cases, a CO 2 sensor installed in the outdoor air intake is also recommended to take into account external CO 2 contributions. • Measurements of CO 2 were carried out in public buses during commuting rush hours. • An evaluation of factors governing ventilation inside the vehicles was carried out, and actions to improve it were suggested. • The opening of the windows in the older buses yielded higher ventilation rates. • The opening of all doors at all stops increases the ventilation by causing a fall in concentrations lasting 40–50 s. • Measurement of CO 2 and occupancy and installation of roof ventilation fans in the hermetically closed new buses. [ABSTRACT FROM AUTHOR]

Urban aerosol samples collected in Barcelona between 2008 and 2009 were toxicologically characterised by means of two complementary methodologies allowing evaluation of their Reactive Oxidative Stress (ROS)-generating capacity: the plasmid scission assay (PSA) and the dichlorodihydrofluorescin assay (DCFH). The PSA determined the PM dose able to damage 50% of a plasmid DNA molecule (TD50 values), an indication of the ability of the sample to exert potential oxidative stress, most likely by formation of ·OH. This toxicity indicator did not show dependency on different air mass origins (African dust, Atlantic advection), indicating that local pollutant sources within or near the city are most likely to be mainly responsible for PM health effect variations. The average TD50 values show PM2.5–0.1 samples to be more toxic than the PM10–2.5 fraction, with doses similar to those reported in previous studies in polluted urban areas. In addition, the samples were also evaluated using the oxidant-sensitive probe DCFH confirming the positive association between the amount of DNA damage and the generation of reactive oxidant species capable of inducing DNA strand break. Results provided by the PSA were compared with those from two other different methodologies to evaluate human health risk: (1) the toxicity of particulate PAHs expressed as the calculated toxicity equivalent of benzo[a]pyrene (BaPteq) after application of the EPA toxicity factors, and (2) the cancer risk assessment of the different PM sources detected in Barcelona with the receptor model Positive Matrix Factorisation (PMF) and the computer programme Multilinear Engine 2 (ME-2) using the organic and inorganic chemical compositions of particles. No positive associations were found between PSA and the toxicity of PAHs, probably due to the inefficiency of water in extracting organic compounds. On the other hand, the sum of cancer risk estimates calculated for each of the selected days for the PSA was found to correlate with TD50 values in the fine fraction, with fuel oil combustion and industrial emissions therefore being most implicated in negative health effects. Further studies are necessary to determine whether toxicity is related to PM chemical composition and sources, or rather to its size distribution. [Copyright &y& Elsevier]

BACKGROUND: Dozens of studies link acute exposure to particulate matter (PM) air pollution with premature mortality and morbidity, but questions remain about which species and sources in the vast PM mixture are responsible for the observed health effects. Although a few studies exist on the effects of species and sources in U.S. cities, European cities.which have a higher proportion of diesel engines and denser urban populations.have not been well characterized. Information on the effects of specific sources could aid in targeting pollution control and in articulating the biological mechanisms of PM. OBJECTIVES: Our study examined the effects of various PM sources on daily mortality for 2003 through 2007 in Barcelona, a densely populated city in the northeast corner of Spain. METHODS: Source apportionment for PM ≤2.5 μm and ≤10 m in aerodynamic diameter (PM2.5 and PM10) using positive matrix factorization identified eight different factors. Case-crossover regression analysis was used to estimate the effects of each factor. RESULTS: Several sources of PM2.5, including vehicle exhaust, fuel oil combustion, secondary nitrate/organics, minerals, secondary sulfate/organics, and road dust, had statistically significant associations (p <.0.05) with all-cause and cardiovascular mortality. Also, in some cases relative risks for a respective interquartile range increase in concentration were higher for specific sources than for total PM2.5 mass. CONCLUSIONS: These results along with those from our multisource models suggest that traffic, sulfate from shipping and long-range transport, and construction dust are important contributors to the adverse health effects linked to PM. [ABSTRACT FROM AUTHOR]

Measurements of particle number concentration (N), black carbon (BC), and PM10, PM2.5, and PM1 levels and speciation were carried out at an urban background monitoring site in Barcelona. Daily variability of all aerosol monitoring parameters was highly influenced by road traffic emissions and meteorology. The levels of N, BC, PMX, CO, NO, and NO2 increased during traffic rush hours, reflecting exhaust, and non-exhaust traffic emissions and then decreased by the effect of breezes and the reduction of traffic intensity. PM2.5-10 levels did not decrease during the day as a result of dust resuspension by traffic and wind. N showed a second peak, registered in the afternoon and parallel to O3 levels and solar radiation intensity, that may be attributed to photochemical nucleation of precursor gases. An increasing trend was observed for PM1 levels from 1999 to 2006, related to the increase in the traffic flow and the diesel fleet in Barcelona. PM composition was highly influenced by road traffic emissions, with exhaust emissions being an important source of PM1 and dust resuspension processes of PM2.5-10, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The insular suburban site of Castillo de Bellver was selected for the study of the variability of PM levels and composition in the Western Mediterranean Basin (WMB). Mean annual (in 2004) PM10 and PM2.5 levels at this site were 29 and 20µg/m3, respectively. These levels may be regarded as relatively low when compared with other suburban insular locations in the Eastern Mediterranean Basin (EMB), but they are higher than those recorded at most of the European suburban sites, especially in Northern and Western Europe. Seasonal variability of PM levels at this site is governed by meteorology rather than local emissions, whereas the daily cycles are clearly defined by the anthropogenic emissions, mainly coming from the urban area of Palma de Mallorca and the harbour area of the same city. Concerning the aerosol composition at this site, the main PM constituent is the mineral matter (29% in PM10 and 16 % in PM2.5), more than 50% (in PM10) being attributable to African dust. The amount of secondary inorganic aerosols is also very high (27% in PM10 and 34% in PM2.5), with the predominance of fine ammonium sulphate, and in a less proportion fine ammonium nitrate (in winter) and coarse Ca and Na nitrate (with higher importance in summer). The carbonaceous particles, dominantly fine, account for 17% of PM10 and 25% of PM2.5. The elemental carbon/organic carbon (EC/OC) ratio reached a mean value of 0.17, similar to those observed at regional background sites in the WMB coast of Spain. The sea spray aerosols (mainly coarse) represented around 10% of PM10, and only 4% in PM2.5. Finally, the unaccounted fraction increased from 15% to 20% in PM2.5, being mostly attributed to water. The concentrations of trace elements in PM10 and PM2.5 were usually in the range to those observed in regional background sites in the Iberian Peninsula, with the exception of the typical tracers of road traffic such as Cu, Sb, Zn, Sn and Ba, which presented concentrations in the range of urban sites of Iberia. Other elements such as Cr, Zr, Hf and Co have been identified as the main tracers of the harbour contributions. [Copyright &y& Elsevier]

Abstract: Despite their burden in urban particulate air pollution, road traffic non-exhaust emissions are often uncontrolled and information about the effectiveness of mitigation measures on paved roads is still scarce. The present study is aimed to evaluate the effectiveness of mechanical sweeping/water flushing treatments in mitigating urban road dust resuspension and to quantify the real benefit in terms of ambient PM10 concentrations. To this aim a specific campaign was carried out in a heavily trafficked central road of Barcelona (Spain), a Mediterranean city suffering from a traffic-related pollution, both for a high car density and a frequent lack of precipitation. Several street washings were performed by means of mechanical sweepers and pressure water during night in all traffic lanes and sidewalks. PM10 levels were simultaneously compared with four reference urban background air quality stations to interpret any meteorological variability. At the downwind measurement site, PM10 concentrations registered a mean daily decrease of 8.8μgm−3 during the 24h after street washing treatments. However 3.7–4.9μgm−3 of such decrease were due to the meteorological variability detected at the upwind site, as well as at two of the reference sites. This reveals that an effective decrease of 4–5μgm−3 (7–10%) can be related to street washing efficiency. Mitigation of road dust resuspension was confirmed by investigating the chemical composition of airborne-PM10 filters. Concentrations of Cu, Sb, Fe and mineral matter decrease significantly with respect to concentrations of elemental carbon, used as tracer for exhaust diesel emissions. High efficiency of street washing in reducing road dust loads was found by performing periodic samplings both on the treated and the untreated areas. [Copyright &y& Elsevier]

Abstract: Extensive measurements on particle number concentration and size distribution (13–800 nm), together with detailed chemical composition of PM2.5 have constituted the main inputs of the database used for a source apportionment analysis. Data were collected at an urban background site in Barcelona, Western Mediterranean. The source identification analysis helped us to distinguish five emission sources (vehicle exhausts, mineral dust, sea spray, industrial source and fuel-oil combustion) and two atmospheric processes (photochemical induced nucleation and regional/urban background particles derived from coagulation and condensation processes). After that, a multilinear regression analysis was applied in order to quantify the contribution of each factor. This study reveals that vehicle exhausts contribute dominantly to the number concentration in all the particle sizes (52–86%), but especially in the range 30–200 nm. This work also points out the importance of the regional and/or urban formed aerosols (secondary inorganic particles) on the total number concentration (around 25% of the total number), with a higher impact on the accumulation mode. The photo-chemically induced nucleation of aerosols only represents a small proportion of the total number as an annual mean (3%), but is very relevant when considering only the nucleation mode (13–20 nm) fraction (23%). The other sources recognized registered sporadic contributions to the total number, coinciding with specific meteorological scenarios. This study discloses the main sources and features affecting and controlling the fine and ultra-fine aerosols in a typical city in the Western Mediterranean coast. Whereas the road traffic appears to be the most important source of sub-micrometric aerosols, other sources may not be negligible under specific meteorological conditions. [Copyright &y& Elsevier]

Ambient PM10 and PM2.5 at Puertollano (central Spain) are derived mostly from local industrial emissions (including a refinery and power stations) and mineral (“crustal”) aerosols from fugitive dusts and African intrusions. Vanadium and the lanthanoid elements (La to Lu) can be used as geochemical markers to help identify these different contributions, especially when combined with atmospheric back-trajectory data. The total lanthanoid (∑Loid) content of PM is controlled primarily by the amount of coarse crustal material present, with the highest values being recorded in PM10 during an African dust intrusion (13ng m−3). In contrast, La/Ce and La/Sm ratios are controlled by fine refinery emissions, rising above natural crustal averages due to the release of La from fluid catalytic converters (FCC), and allowing the identification of La anomalies (La>Ce) when FCC emissions are prominent. Crustal La/Ce ratios are least common, and La anomalies most common, in PM2.5 measured during local pollution events. Increasing contamination of urban/industrial atmospheric PM samples away from crustal compositions may be tracked using a LaCeSm triangular plot, but this does not differentiate between FCC refinery and oil combustion emissions. Comparing lanthanoid and V concentrations does aid such differentiation, although given the likelihood of multiple PM sources in industrial locations, we recommend use of a LaCeV plot rather than simply La/V ratios. [Copyright &y& Elsevier]

The use of fireworks creates an unusual and distinctive anthropogenic atmospheric pollution event. We report on aerosol samples collected during Las Fallas in Valencia, a 6-day celebration famous for its firework displays, and add comparative data on firework-and bonfire-contaminated atmospheric aerosol samples collected from elsewhere in Spain (Barcelona, L’Alcora, and Borriana) and during the Guy Fawkes celebrations in London. Specific high-profile official firework events during Las Fallas included the afternoon Mascletà and the nightly aerial displays (especially in the climactic final 2 days of the fiesta) and were accompanied by pollution spikes in suspended particles, NO, SO2, and the creation and dispersal of an aerosol cloud enriched in a range of metallic elements. Notable metal aerosol concentration increases recorded during Las Fallas were potassium (from 500 to 5900ngm−3), aluminium (as Al2O3 from around 600 to 2200ngm−3), titanium (from 200 to 700ngm−3), magnesium (from 100 to 500ngm−3), lead (from 17 to 379ngm−3), barium (from 39 to 322ngm−3), strontium (from 3 to 112ngm−3), copper (from 12 to 71ngm−3), and antimony (from 1 to 52ngm−3). Firework-contaminated aerosols of similarly metalliferous composition were also identified at the other monitoring sites, although different sites show variations attributable to other sources such as bonfires and local industry. Unusual levels of the trace elements Ba, Sr and (to a lesser extent) Cu, always in proportions with Ba dominant, along with strongly enhanced K, Pb, and Sb, are identified as being particularly characteristic of firework aerosols. Although firework-related recreational pollution episodes are transient in nature, they are highly concentrated, contribute significantly to total annual metal emissions, and are on average fine enough to be easily inhaled and a health risk to susceptible individuals. [Copyright &y& Elsevier]

The origin of the daily exceedances of 50μg PM10m−3 (daily limit value or DLV of the EU air quality directive) and of an arbitrary daily value (DV) 35μg PM2. 5m−3 recorded in 2001–2003 in 13 regional background stations of the Iberian Peninsula were interpreted. This was carried out by means of back-trajectory analysis, available PM model outputs, satellite data and meteorological maps. This allows the detection of high PM episodes on a regional scale and the study of their seasonal and geographical variability. The number of exceedances of the PM10 DLV ranged in 2001–2003 from 6 to 41 depending on the monitoring site. For the selected PM2. 5DV, the range of daily exceedances was 0–10 in the study period. The majority of the PM10 (>70% in most stations) and PM2. 5 (17–55% in most stations) exceedances in regional background monitoring stations are caused by African dust outbreaks. These exceedances were less frequent in winter than in summer due to: (a) the frequent long range transport of dust in the warm seasons over Iberia, (b) the re-suspension associated with convective atmospheric dynamics, and (c) the relative low rainfall favouring re-suspension and high residence time of PM. Moreover, a regional contribution of secondary aerosols derived from the efficient photochemical transformation of gaseous precursors may coincide with African transport in summer. Episodes with lack of advective conditions caused 2–29% and 20–50% of the PM10 and PM2. 5 exceedances. These occurred mainly in summer due to poor renovation of air masses, increased convective re-suspension, dispersion of pollutants towards rural areas and regional re-circulation and aging of air masses which result in the proliferation of secondary inorganic species. Long-range transport of PM from continental Europe caused exceedances (9–40% and 18–38% of the PM10 and PM2. 5 exceedances, respectively), only in northern Iberia because, as the European air masses evolve towards the south, the pollutants suffer dispersion/dilution. Local exceedances are associated with the advection of the clean Atlantic air masses, which cannot increase PM levels to a great extent without the influence of a local source of PM. The proportion of local exceedances of PM10 and PM2. 5 ranged 6–33% and 17–40%, respectively. [Copyright &y& Elsevier]

Abstract: A 12-month study of PM10 and gases in the industrial Spanish town of Puertollano reveals striking variations in pollutant concentrations. The normal daily pollution pattern is characterised by a daily double peak for NO x and CO and associated double trough for ozone (morning and evening), a midday atmospheric fumigation peak for SO2 and PM10 (1–2h later in winter), and a late morning through afternoon maximum for ozone (shorter and lower in winter). Superimposed upon this are: (1) seasonal variations, which accentuate the PM10 and SO2 mid-morning peaks in winter (when the peak occurs later than in summer), raise NO2, ozone and background particulate levels during the summer, and favour enhanced levels of NO during the winter; (2) local pollution spikes, particularly those associated with SO2 release from nearby industrial sources; (3) regional atmospheric stagnation episodes, which enhance concentrations of all pollutants and (4) intrusion of exotic pollutants, notably desert dust from North Africa. Given that air pollutants are known adversely to influence human health, understanding and predicting such diurnal variations in concentrations of inhalable pollutants is especially relevant to susceptible individuals such as asthmatics. [Copyright &y& Elsevier]

Abstract: The area of Castilla-La Mancha in central Spain is repeatedly visited by mineral dust incursions from the deserts of NW Africa. Such exotic atmospheric intrusions raise background PM10 levels, making urban areas much more likely to exceed daily limits of 50μgm−3 and become subject to fines under European environmental law. Data from a 3-year (2001–2003) study of hourly PM10 values demonstrate that average background dust levels in remote sites rise from 6–8μgm−3 when Atlantic-derived W/SW winds are blowing, to 24–7μgm−3 when African events take place. In four Castilla-La Mancha towns, numbers of exceedence days (ED: when PM10>50μgm−3) per year averaged 31 in Guadalajara (suburban site with annual daily PM10 average ADPM10=27μgm−3), 68 in Toledo (ADPM10=38μgm−3) and 139 in Albacete (ADPM10=47μgm−3; both urban sites), and 151 in Puertollano (industrial urban site with ADPM10=51μgm−3). Thirty-four percent of ED occurred during African dust incursions, and current law allows exclusion of such days from annual data (which also reduces the ADPM10 by 2–4μgm−3). Rather than simply excluding such days, a more scientifically satisfactory approach would be to allow subtraction of the estimated component of exotic background dust present daily at every urban monitoring station, and thus identify towns subject to high levels of locally derived anthropogenic PM10. Such an approach reduces ADPM10 values by the same amount as above (2–4μgm−3) if only African-derived PM10 values (as measured at remote background stations) are subtracted, although ΣED shows a relative increase. If, however, an attempt is made to estimate and subtract the total amount of exotic PM10 (i.e. not just African non-locally derived) at the four sites, this reduces the ADPM10 by 8–12μgm−3, and ΣED also drops significantly. Whichever approach is adopted, however, our data confirm that the legally allowable number of ED is far more strict than the annual limit value. This inconsistency will make it especially difficult for many southern European towns, with their abundant dry dust resuspension and regular incursions of African dust, to achieve PM exceedence targets in 2005. We argue that further refinement of aerosol pollution law is necessary to ensure that penalties for exceeding legally acceptable levels of atmospheric particulates are scientifically well founded and fair. [Copyright &y& Elsevier]

Air pollution coming from industrial activities is a matter of interest since their emissions can seriously affect to the human health of nearby populations. A more detailed study about industrial emissions is required in order to discriminate different activities contributing to pollutant sources. In this sense, gaseous pollutants (NO 2 , SO 2 and O 3) and PM10 levels has been studied in a complex industrial area in the southwest of Spain (La Rabida and the nearby city of Huelva) during the period 1996–2017. Hourly, daily, monthly and annual variations of PM10 and gaseous pollutants concentrations point to the industrial activity as the main SO 2 source. Furthermore, traffic and resuspension emissions contribute to the NO 2 and PM10 levels, respectively. Results from chemical composition of PM10 at both sites during the period 2015–2017 are characterized by high concentrations of the crustal components derived from natural and local resuspension. Arsenic is found to be the main geochemical anomaly at La Rabida (annual mean of 7 ng m−3), exceeding the European annual target of 6 ng m−3, which supposes a risk for the nearby population. An emission source from Cu-smelter has been identified in La Rabida and Huelva. A second source corresponding to emissions from polymetallic sulfides handling in a port area has been described for the first time in La Rabida. In addition, arsenic speciation results have identified three different As impacts scenarios as a function of the dominant wind direction, the SO 2 episodes and the As extraction efficiency: impact of the Cu-smelter, impact of the bulk polymetallic sulfides and a mixed impact of both sources. Image 1 • Trends of PM10 and gaseous pollutants were studied in SW Spain in a 21-year period. • High As concentrations were observed for the period 2015–2017 at the sampling site. • Cu smelter and polymetallic sulfides were identified as the As emissions sources. • As speciation analysis allowed to discriminate two industrial emission sources. [ABSTRACT FROM AUTHOR]

Abstract: Background: Studies measuring health effects of Saharan dust based on large particulate matter (PM) fraction groups may be masking some effects. Long distant transport reduces the amount of heavier and larger particles in the Saharan air masses increasing the relative contribution of smaller particles that may be more innocuous. This study investigates the association between different PM fractions and daily mortality during Saharan and non-Saharan days in Barcelona, Spain. Methods: We collected daily PM1, PM2.5–1 and PM10–2.5 fractions, and cause-specific mortality (cardiovascular, respiratory and cerebrovascular) between March 2003 and December 2007. Changes of effects between Saharan and non-Saharan dust days were assessed using a time-stratified case–crossover design. Results: During non-Saharan dust days we found statistically significant (p<0.05) effects of PM10–2.5 for cardiovascular (odds ratio for increase of an interquartile range, OR=1.033, 95% confidence interval: 1.006–1.060) and respiratory mortality (OR=1.044, 95% CI: 1.001–1.089). During Saharan dust days strongest cardiovascular effects were found for the same fraction (OR=1.085, 95% CI: 1.017–1.158) with an indication of effect modification (p=0.111). Effects of PM2.5–1 during Saharan dust days were about the double than in non-dust days for cardiovascular and respiratory mortality, but these differences were not statistically significant. Conclusion: Our results using independent fractions of PMs provide further evidence that the effects of short-term exposure to PM during Saharan dust days are associated with both cardiovascular and respiratory mortality. A better understanding of which of the different PM size fractions brought by Saharan dust is more likely to accelerate adverse effects may help better understand mechanisms of toxicity. [Copyright &y& Elsevier]

The relationship between specific particulate emission control and ambient levels of some PM10 components (Zn, As, Pb, Cs, Tl) was evaluated. To this end, the industrial area of Castellón (Eastern Spain) was selected, where around 40% of the EU glazed ceramic tiles and a high proportion of EU ceramic frits are produced. The PM10 emissions from the ceramic processes were calculated over the period 2000 to 2006, taking into account the degree of implementation of corrective measures throughout the study period. Abatement systems were implemented in the majority of the fusion kilns for frit manufacture in the area as a result of the application of the Directive 1996/61/EC, leading to a marked decrease in PM10 emissions. By contrast, emissions from tile manufacture remained relatively constant because of the few changes in the implementation of corrective measures. On the other hand, ambient PM10 levels and composition measurements were carried out from 2002 to 2006. A high correlation between PM10 emissions from frit manufacture and ambient levels of Zn, As, Pb and Cs (R 2 from 0.61 to 0.98) was observed. On the basis of these results, the potential impact of the implementation of corrective measures to reduce emissions from tile manufacture was quantified, resulting in a possible decrease of 3¿5¿g/m3 and 2¿g/m3 in ambient mineral PM10 (on an annual basis) in urban and suburban areas, respectively. This relatively simple methodology allows us to estimate the direct effect of a reduction in primary particulate emissions on ambient levels of key particulate components, and to make a preliminary quantification of the possibilities of air quality improvement by means of further emission reduction. Therefore, it is a useful tool for developing future air quality plans in the study area and in other industrialised areas. [Copyright &y& Elsevier]

The results of chemical analysis of PM10 atmospheric dust samples collected between July 2001 and June 2002 in rural and urban background monitoring stations in Huelva (South-western Spain) are reported. In order to identify the sources and quantify their contribution to PM10, principal component analysis and receptor modelling techniques were performed using independent variables of the complete series of concentrations of PM10 contents. The Ria of Huelva is considered to be one of the high industrial estates in Spain, where several metallurgical, petrochemical and fertilizer industrial estates are located, surrounded by areas of a high ecological interest such as Doñana National Park. Annual means of 29–33 and 37μg PM10 m−3 were obtained for the study period in rural and urban monitoring stations, respectively. These values are below the mean annual limit value for 2005 and onwards from the Directive 1999/30/EC [EU, 1999. 1999/30/CE Council Directive relating to limit values for sulphur dioxide, nitrogen dioxide and oxide of nitrogen, particulate matter and lead in ambient air. The Council of the European Union]. High PM10 episodes in rural and urban areas occurred during African dust events. Episodically, the emissions of plumes from industrial estates reach rural areas causing peak episodes of Cu, Ti Pb and As. Anthropogenic particles arising from metallurgical emissions (pyrite, chalcopyrite and sphalerite) were observed in the rural sites. The annual mean As concentrations measured in PM10 in the city of Huelva and surrounding rural areas (144 and 84–51mg Askg−1 in PM10, respectively) are several times high the concentrations obtained in other Spanish monitoring stations (7–57mg Askg−1). The source apportionment analyses allowed the quantification of the contribution to PM10 of an industrial mixed source in the rural background. [Copyright &y& Elsevier]

Abstract: This study applies a methodology for discriminating local and external contributions of atmospheric particulate matter (PM) at a rural background station in the North-western coast of Spain. The main inputs at the nearest scale have come from soil dust, marine aerosol and road traffic. At a larger scale, the highest contributions have come from fossil-fuel combustion sources, giving rise to relatively high ammonium sulphate background levels, mainly in summer. External contributions from long-range transport processes of African dust and nitrate have been detected. Morocco and Western Sahara have been identified as the main potential source regions of African dust, with a higher content of Al and Ti than other crustal components. Geographical areas from central and Eastern Europe have been identified as potential sources of particulate nitrate. The discrimination of the PM contribution from natural and anthropogenic sources at different geographical scales is a necessary information for establishing PM reduction strategies in specific areas. [Copyright &y& Elsevier]

Understanding the atmospheric processes involving carbonaceous aerosols (CAs) is crucial for assessing air pollution impacts on human health and climate. The sources and formation mechanisms of CAs are not well understood, making it challenging to quantify impacts in models. Studies suggest residential wood combustion (RWC) and traffic significantly contribute to CAs in Europe's urban and rural areas. Here, we used an atmospheric chemistry model (MONARCH) and three different emission inventories (two versions of the European-scale emission inventory CAMS-REG_v4 and the HERMESv3 detailed national inventory for Spain) to assess the uncertainties in CAs simulation and source allocation (from traffic, RWC, shipping, fires and others) in Northeast Spain. For this, black carbon (BC) and organic aerosol (OA) measurements performed at three supersites representing different environments (urban, regional and remote) were used. Our findings show the importance of model resolution and detailed emission input data in accurately reproducing BC/OA observations. Even though emissions of total particulate matter are rather consistent between inventories in Spain, we found discrepancies between them mainly related to the spatiotemporal disaggregation (particularly relevant for traffic and RWC) and the treatment of the condensable fraction of CAs in RWC (changes in the speciation of elemental/organic carbon). The main source contribution to BC concentrations in the urban site is traffic, accounting for 71.1 % / 65.2 % (January/July) in close agreement with the fossil contribution derived from observations (78.8 % / 84.2 %), followed by RWC (12.8 % / 3 %) and shipping emissions (5.4 % / 13.8 %). An over-representation of RWC (winter) and shipping (summer) is obtained with CAMS-REG_v4. Noteworthy uncertainties arise in OA results due to condensables in emissions and a limited secondary aerosol production in the model. These findings offer insights into MONARCH's effectiveness in simulating CAs concentrations and source contribution in Northeast Spain. The study highlights the benefits of combining new datasets and modeling techniques to refine emission inventories and better understand and mitigate air pollution impacts. [ABSTRACT FROM AUTHOR]

In highly industrialized areas, abating particulate matter (PM) is complex owing to the variety of emission sources with different chemical profiles that may mix in the atmosphere. Gijón—an industrial city in northern Spain—was selected as a case study to better understand the key emission sources and improve air quality in highly industrialized areas. Accordingly, the trends of various air quality indicators (PM10, PM2.5, SO 2 , NO 2 , and O 3) during the past decade (2010–2019) were analyzed. Additionally, the inorganic and organic PM10 compositions were analyzed for source apportionment studies and to assess the impact of COVID-19 restrictions on PM10 levels. The results revealed that over the past decade, PM10 concentrations decreased, whereas PM2.5 concentrations dominated by secondary inorganic aerosols (SIA) remained relatively constant. Notably, during the COVID-19 lockdown, the PM10 concentration increased by 9.1%, primarily owing to an increase in regional SIA (>65%) due to specific meteorological conditions that favor the formation of secondary PM from gaseous precursors. Overall, eight key PM10 sources were identified: "industrial fugitive PM resuspension" (FPM, 28% of mean PM10 concentration), "aged sea spray" (SSp, 16%), "secondary nitrate" (SN, 15%), "local diffuse source" (LPM, 12%), "solid fuel combustion" (SFC, 7.8%), "biomass burning" (BB, 7.4%), "secondary sulphate" (SSu, 6.0%), and "sinter" (SIN, 4.5%). The PM10 concentration in Gijón is significantly influenced by the integrated steel industry (FPM, SFC, and SIN; 41% of PM10) and fugitive primary PM emissions were the main source (FPM and LPM; 40%). To reduce PM10 and PM2.5 concentrations, industrial fugitive emissions, which are currently poorly regulated, and SIA precursors must be abated. This study provides a methodological approach that combines trend analysis, chemical speciation, and source apportionment for assessing pollution abatement strategies in industrialized areas with a complex mix of emission sources. [Display omitted] • Complex industrial areas complicate PM source apportionment due to diverse emissions. • Concentrations decreased for PM10 but not for PM2.5 during last decade in Gijón. • Reducing secondary aerosol precursors is critical to abate PM2.5 levels. • Fugitive PM emissions from steelworks constitute a significant PM10 source. • Secondary PM formation may have caused an increase in PM during the COVID-19 lockdown. [ABSTRACT FROM AUTHOR]

Vehicle interior air quality (VIAQ) was investigated inside 14 diesel/non-diesel taxi pairs operating simultaneously and under normal working conditions over six weekday hours (10.00–16.00) in the city of Barcelona, Spain. Parameters measured included PM 10 mass and inorganic chemistry, ultrafine particle number (N) and size, lung surface deposited area (LDSA), black carbon (BC), CO 2 , CO, and a range of volatile organic compounds (VOCs). Most taxi drivers elected to drive with windows open, thus keeping levels of CO 2 and internally-generated VOCs low but exposing them to high levels of traffic-related air pollutants entering from outside and confirming that air exchange rates are the dominant influence on VIAQ. Median values of N and LDSA (both sensitive markers of VIAQ fluctuations and likely health effects) were reduced to around 104 #/cm3 and < 20 µm2/cm3 respectively under closed conditions, but more than doubled with windows open and sometimes approached 105 #/cm3 and 240 µm2/cm3. In exceptional traffic conditions, transient pollution peaks caused by outside infiltration exceeded N = 106 #/cm3 and LDSA= 1000 µm2/cm3. Indications of self-pollution were implicated by higher BC and CO levels, and larger UFP sizes, measured inside diesel taxis as compared to their non-diesel pair, and the highest concentrations of CO (>2 ppm) were commonly associated with older, high-km diesel taxis. Median PM 10 concentrations (67 µg/m3) were treble those of urban background, mainly due to increased levels of organic and elemental carbon, with source apportionment calculations identifying the main pollutants as vehicle exhaust and non-exhaust particles. Enhancements in PM 10 concentrations of Cr, Cu, Sn, Sb, and a "High Field Strength Element" zircon-related group characterised by Zr, Hf, Nb, Y and U, are attributed mainly to the presence of brake-derived PM. Volatile organic compounds display a mixture which reflects the complexity of traffic-related organic carbon emissions infiltrating the taxi interior, with 2-methylbutane and n-pentane being the most abundant VOCs, followed by toluene, m-xylene, o-xylene, 1,2,4-trimethylbenzene, ethylbenzene, p-xylene, benzene, and 1,3,5-trimethylbenzene. Internally sourced VOCs included high monoterpene concentrations from an air freshener, and interior off-gassing may explain why the youngest taxi registered the highest content of alkanes and aromatic compounds. Carbon dioxide concentrations quickly climbed to undesirable levels (>2500 ppm) under closed ventilation conditions and could stay high for much of the working day. Taxi drivers face daily occupational exposure to traffic-related air pollutants and would benefit from a greater awareness of VIAQ issues, notably the use of ventilation, to encourage them to minimise possible health effects caused by their working environment. • Main PM 10 sources inside taxis are vehicle exhaust and non-exhaust (wear) particles. • PM 10 averaged 67 µg/m3 and enriched in Cr, Cu, Sn, Sb, Zr attributed to brake wear. • Self-pollution inside (especially older) diesel taxis raises BC, CO, and UFP size. • VOCs inside taxi dominated by 2-methylbutane, n-pentane and other exhaust emissions. • Intelligent use of taxi ventilation reduces infiltration and build-up of pollutants. [ABSTRACT FROM AUTHOR]

This study aims to support the development of Spain's Ozone Mitigation Plan by evaluating the present-day spatial variation (2015–2019) and trends (2008–2019) for seven ground-level ozone (O 3) metrics relevant for human/ecosystems exposure and regulatory purposes. Results indicate that the spatial variation of O 3 depends on the part of the O 3 distribution being analyzed. Metrics associated with moderate O 3 concentrations depict an increasing O 3 gradient between the northern and Mediterranean coasts due to climatic factors, while for metrics considering the upper end of the O 3 distribution, this climatic gradient tends to attenuate in favor of hotspot regions pointing to relevant local/regional O 3 formation. A classification of atmospheric regions in Spain is proposed based on their O 3 pollution patterns, to identify priority areas (or O 3 hotspots) where local/regional precursor abatement might significantly reduce O 3 during pollution episodes. The trends assessment reveals a narrowing of the O 3 distribution at the national level, with metrics influenced by lower concentrations tending to increase over time, and those reflecting the higher end of the O 3 distribution tending to decrease. While most stations show no statistically significant variations, contrasting O 3 trends are evident among the O 3 hotspots. The Madrid area exhibits the majority of upward trends across all metrics, frequently with the highest increasing rates, implying increasing O 3 associated with both chronic and episodic exposure. The Valencian Community area exhibits a mixed variation pattern, with moderate to high O 3 metrics increasing and peak metrics decreasing, while O 3 in areas downwind of Barcelona, the Guadalquivir Valley and Puertollano shows no variations. Sevilla is the only large Spanish city with generalized O 3 decreasing trends. The different O 3 trends among hotspots highlight the need for mitigation measures to be designed at a local/regional scale to be effective. This approach may offer valuable insights for other countries developing O 3 mitigation plans. [ABSTRACT FROM AUTHOR]

Copper smelters represent a major anthropogenic source of SO 2 and sulphide-related elements into particulate matter, affecting the air quality of the surrounding areas. The implementation of measures to reduce the emission of gaseous contaminants and particles in industrial processes is a major issue, which aims to establish technological progress for cleaner production. In this sense, a long-range study covering the period 2001–2015 has been performed in the SW Spain, where one of the largest Cu-smelters in Europe is located. Trends of PM 10 and PM 2.5 levels and geochemical patterns were studied considering the following periods: prior (2001–2008), during (2009–2013) and after (2014–2015) the implementation of emission abatement technology (wet electrofilters, bag filters and lime injection) by this large industrial facility. The results evidenced relatively high concentrations of sulphide-related elements (annual mean of 6.1, 1.7, 0.7, 2.2, 2.0, 21.0 and 1.0 ng m −3 for As, Se, Cd, Sn, Sb, Pb and Bi, respectively) during 2001–2008. A reduction of 50% was observed for the last period (2.8, 0.5, 0.2, 1.6, 1.1, 6.7 an d 0.3 ng m −3 for the same elements, respectively) in PM 10 . A similar trend was observed for PM 2.5 samples. However, the number of episodes of SO 2 has not changed along the studied period (average 8 days/month), although the SO 2 concentration during the pollution episodes has markedly diminished from maximum peak concentrations of 350 μg m −3 to 170 μg m −3 . A high arsenic concentration is the main geochemical anomaly found in PM, reaching annual mean concentrations up to 10.4 ng m −3 in 2005 above the annual EU target value (6 ng m −3 ) in PM 10 , decreasing down to 2.7 and 2.9 ng m −3 in 2014 and 2015, respectively. However, sporadically high episodic levels are still recorded (e.g. 26.8 ng m −3 in 2014 and 14.9 ng m −3 in 2015). [ABSTRACT FROM AUTHOR]

Background Evidence on the short-term effects of ultrafine particles (with diameter < 100 nm, UFP) on health is still inconsistent. New particles in ambient urban air are the result of direct emissions and also the formation of secondary UFP from gaseous precursors. We segregated UFP into these two components and investigated their impact on daily mortality in three Spanish cities affected by different sources of air pollution. Methods We separated the UFP using a method based on the high correlation between black carbon (BC) and particle number concentration (N). The first component accounts for aerosol constituents emitted by vehicle exhaust (N1) and the second for the photochemical new particle formation enhancements (N2). We applied city-specific Poisson regression models, adjusting for long-term trends, temperature and population dynamics. Results Mean BC levels were higher in Barcelona and Tenerife (1.8 and 1.2 μg·m − 3 , respectively) than in Huelva (0.8 μg·m − 3 ). While mean UFP concentrations were similar in the three cities, from which N1 was 40% in Barcelona, 46% in Santa Cruz de Tenerife, and 27% in Huelva. We observed an association with N1 and daily mortality in Barcelona, by increasing approximately 1.5% between lags 0 and 2, per an interquartile increase (IQR) of 3277 cm − 3 , but not with N2. A similar pattern was found in Santa Cruz de Tenerife, although none of the associations were significant. Conversely, in the industrial city of Huelva mortality was associated with N2 at lag 0, by increasing 3.9% per an IQR of 12,032·cm − 3 . Conclusion The pattern and origin of UFP determines their short-term effect on human health. BC is possibly the better parameter to evaluate the health effects of particulate vehicle exhaust emissions, although in areas influenced by domestic solid fuel combustion this should also be taken into account. [ABSTRACT FROM AUTHOR]

Air quality in nine National Parks in mainland Spain was assessed analysing SO 2 , NO x , O 3 , PM 10 and PM 2.5 data from background stations. As emissions in and around parks are limited, the levels of primary pollutants are low. Concentrations of secondary pollutants are high especially in summer due to photochemical production. The geographical variability of pollutants responds to regional emission patterns and the dominant circulation regimes in different regions resulting in west-east gradients for O 3 and PM . Seasonal variability of pollutants was also interpreted in virtue of transport scenarios, changes in photochemical activity and emissions variability. NO x and SO 2 , maximize in winter due to higher emissions while O 3 and PM do it in summer due to photochemical production, lower precipitation and, in the case of PM , the occurrence of African dust outbreaks. The diurnal evolution was interpreted in virtue of variability in emissions and changes in the Planetary Boundar Layer height. [ABSTRACT FROM AUTHOR]

Abstract: In spite of the high air quality and health relevance of PM emissions from road dust resuspension in large cities, very little is known on their temporal variability, severely hampering a reliable description of population exposure by dispersion models. We have experimentally monitored the mobile dust load (only inhalable fraction) in two different European urban environments resulting in the first empirical description of the temporal variation of road dust emission strength. In Central (The Netherlands) and Southern (Spain) European environments the loadings of mobile road dust particles <10 μm were found to be generally constant on a day-to-day scale, except during and in the hours immediately after rain events when the mobility of particles drops dramatically to values close to zero. After the rain event the mobile dust load increases exponentially tending to reach again the maximum value, result of the equilibrium between mobilization/buildup of dust and moistening/resuspension processes. The mobilization/buildup of particles smaller than 10 μm was found to be three times faster in Barcelona than in Utrecht, in relation to higher solar radiation. In Barcelona the recovery of mobile road dust reached 50%, 75%, and 90% of the maximum value after 8, 16 and 27 h, respectively. These values were independent of amounts of rain. In Utrecht the same thresholds were reached after, 28, 55 and 90 h, respectively. Our observations may suggest that, for reducing road dust emissions, light but frequent moistening of roads might be more effective than intensive occasional cleanings. [Copyright &y& Elsevier]

Abstract: Urban NH3 concentrations were mapped in Barcelona (Spain) by means of passive samplers (dosimeters). Average NH3 levels were 9.5 μg m−3 in summer and 4.4 μg m−3 in winter, higher than those reported in other urban background sites in Europe, this being especially notable in summer. During this season, values were significantly higher at urban background than at traffic sites, probably indicating the impact of emissions from biological sources, such as humans, sewage systems and garbage containers. Thus, the volatilization of NH3 from the aerosol phase seems to be significant enough during summer to dominate over traffic emissions. Conversely, in winter levels were higher at traffic sites, suggesting a contribution from vehicle emissions. Indeed, NH3 levels decreased by 55% with increasing distance (50 m) to the direct emissions from traffic. A significant correlation between NH3 concentrations averaged for the different districts of the city and the number of waste containers per hm2 was also obtained, highlighting the necessity for controlling and reducing the emissions from garbage collection systems. The urban topography of the Barcelona historical city centre, characterised by narrow streets with a high population density, seemed to exert a strong influence on NH3 levels, with levels reaching up to 30 μg m−3 as a consequence of limited dispersion and ventilation conditions. The impact of the sewage system emissions was also detected with an increase of levels when measuring immediately above the source, even though further studies are required to evaluate the relevance of these emissions. [Copyright &y& Elsevier]

A full-scale field study was carried out at two Spanish coal-fired power plants equipped with electrostatic precipitator (ESP) and wet flue gas desulfurisation (FGD) systems to investigate the distribution of boron in coals, solid by-products, wastewater streams and flue gases. The results were obtained from the simultaneous sampling of solid, liquid and gaseous streams and their subsequent analysis in two different laboratories for purposes of comparison. Although the final aim of this study was to evaluate the partitioning of boron in a (co-)combustion power plant, special attention was paid to the analytical procedure for boron determination. A sample preparation procedure was optimised for coal and combustion by-products to overcome some specific shortcomings of the currently used acid digestion methods. In addition boron mass balances and removal efficiencies in ESP and FGD devices were calculated. Mass balance closures between 83 and 149% were obtained. During coal combustion, 95% of the incoming boron was collected in the fly ashes. The use of petroleum coke as co-combustible produced a decrease in the removal efficiency of the ESP (87%). Nevertheless, more than 90% of the remaining gaseous boron was eliminated via the FGD in the wastewater discharged from the scrubber, thereby causing environmental problems. [Copyright &y& Elsevier]

Abstract: The primary aim of this study was to quantify the contribution of road dust to airborne particulate matter (PM10) and evaluate the effects of street washing on the mitigation of resuspension. With this purpose an intensive campaign was carried out in a heavily trafficked central road of Madrid (Spain) including PM10 sampling and chemical analysis. PM10 daily levels during dry, unwashed conditions were 2–15% higher than those present during the day after nightly street washing. However, this reduction is lower than the standard deviation of the PM10 measurements. The diurnal variation of PM10 revealed that a reduction in PM10 was noticeable only during the morning hours. The emission sources for the urban area of Madrid were resolved by means of a receptor model, Positive Matrix Factorization, PMF. The results showed that the main sources were vehicle emissions, road dust, secondary aerosol including sulphate and nitrate, and soil. Vehicle emissions and road dust were the major contributor to PM10 particle mass with similar average contributions of 31% and 29% respectively. The effect of street washing was also evaluated by examining the daily variation of the road dust source contribution between days with and without street washing. The mass contribution from the road dust source was ∼2 μg m−3 lower during the days that street washing was implemented with this corresponding to a reduction of 15% of its mass contribution during the days that the road surface was left untreated. [Copyright &y& Elsevier]

Remodelling works are frequent in harbour areas, given that they must adapt to rapidly changing market requirements. Depending on their nature (construction, demolition, etc.), these works may be carried out during long periods of time and thus exert a significant impact on the air quality at the harbours and their surroundings. The air quality at the Valencia harbour was studied during an enlargement project. Four sampling stations aimed to cover the major dust-emitting activities in the harbour. In addition, a sampling campaign was carried out to collect dust materials at their emission sources (e.g., loading and unloading of clinker and petroleum coke, as well as the enlargement works). Differences obtained between PM levels at the monitoring sites were correlated with the distance between sampling stations and enlargement works and/or harbour operations, as well as with the preferential wind direction. In all cases, the days with the highest PM_10 levels were linked to wind directions coinciding with the location of the enlargement works or the clinker and petroleum coke stocks. Classic source apportionment methodologies (PCA and CMB) were applied to the data, but their interpretation was complex due to the similar chemical signatures of PM originating from direct and fugitive emissions from stocked materials (e.g., clinker), and the enlargement works. To overcome this difficulty, a novel non-statistical approach was used to obtain quantitative estimations of the contributions from sources (petroleum coke and clinker), based on the correlation between specific PM components (e.g., carbonaceous species) and source tracers (e.g., V). Finally, a qualitative test using phenolphthalein was devised to identify the presence of clinker on the filters, which provided positive results. This novel tracer approach is thus recommended for harbour authorities. [Copyright &y& Elsevier]

Outdoor levels of fine particles (PM2. 5; particles <2. 5μm) have been associated with cardiovascular health. Persons with existing cardiovascular disease have been suggested to be especially vulnerable. It is unclear, how well outdoor concentrations of PM2. 5 and its constituents measured at a central site reflect personal exposures in Southern European countries. The objective of the study was to assess the relationship between outdoor and personal concentrations of PM2. 5, absorbance and sulphur among post-myocardial infarction patients in Barcelona, Spain. Thirty-eight subjects carried personal PM2. 5 monitors for 24-h once a month (2–6 repeated measurements) between November 2003 and June 2004. PM2. 5 was measured also at a central outdoor monitoring site. Light absorbance (a proxy for elemental carbon) and sulphur content of filter samples were determined as markers of combustion originating and long-range transported PM2. 5, respectively. There were 110, 162 and 88 measurements of PM2. 5, absorbance and sulphur, respectively. Levels of outdoor PM2. 5 (median 17μgm3) were lower than personal PM2. 5 even after excluding days with exposure to environmental tobacco smoke (ETS) (median after exclusion 27μgm3). However, outdoor concentrations of absorbance and sulphur were similar to personal concentrations after exclusion of ETS. When repeated measurements were taken into account, there was a statistically significant association between personal and outdoor absorbance when adjusting for ETS (slope 0. 66, p<0. 001), but for PM2. 5 the association was weaker (slope 0. 51, p=0. 066). Adjustment for ETS had little effect on the respective association of S (slope 0. 69, p<0. 001). Our results suggest that outdoor measurements of absorbance and sulphur can be used to estimate both the daily variation and levels of personal exposures also in Southern European countries, especially when exposure to ETS has been taken into account. For PM2. 5, indoor sources need to be carefully considered. [Copyright &y& Elsevier]

Abstract: An arsenic speciation study has been performed in PM10 samples collected on a fortnight basis in the city of Huelva (SW Spain) during 2001 and 2002. The arsenic species were extracted from the PM10 filters using a NH2OH·HCl solution and sonication, and determined by HPLC–HG–AFS. The mean bulk As concentration of the samples analyzed during 2001 and 2002 slightly exceed the mean annual 6ngm−3 target value proposed by the European Commission for 2013, arsenate [As(V)] being responsible for the high level of arsenic. The speciation analyses showed that As(V) was the main arsenic species found, followed by arsenite [As(III)] (mean 6.5 and 7.8ngm−3 for As(V), mean 1.2 and 2.1ngm−3 for As(III), in 2001 and 2002, respectively). The high levels of arsenic species found in PM10 in Huelva have a predominant industrial origin, such as the one from a nearby copper smelter, and do not present a seasonal pattern. The highest daily levels of arsenic species correspond to synoptic conditions in which the winds with S and SW components transport the contaminants from the main emission source. The frequent African dust outbreaks over Huelva may result in an increment of mass levels of PM10, but do not represent a significant input of arsenic in comparison to the anthropogenic source. The rural background levels of arsenic around Huelva are rather high, in comparison to other rural or urban areas in Spain, showing a relatively high atmosphere residence time of arsenic. This work shows the importance of arsenic speciation in studies of aerosol chemistry, due to the presence of arsenic species [As(III) and As(V)] with distinct toxicity. [Copyright &y& Elsevier]

A source apportionment study was performed to characterise PM10 sources in the urban area of Madrid. Receptor modelling techniques were applied to obtain the different source contributions, identifying four main sources that contribute to most of the analysed PM10 mass, namely: road traffic, crustal/mineral, secondary and marine aerosol. PM10 mean concentration and chemical profile were obtained for each source category by multilinear regression analysis. Road traffic was found to be the major contributor to the PM10 mass (48%), together with crustal (26%) and secondary particles (18%). A minor contribution has been associated to marine aerosol (3%), while 5% of the PM10 mass has been attributed to non-identified sources. An analysis of the geographical origin was performed for remote sources. Residence time probability values were calculated based on air mass back trajectories information. Different elements have been selected as tracers of the sources. Desertic regions from North Africa have been identified as the most significant source area for crustal particles, with a high content of Al and Ti. Atlantic ocean regions have been identified as weak to intermediate source areas of Na, supporting the marine source identified by the factor analysis. Then the influence of remote natural sources on the PM10 levels in central Spain has been detected by the use of single components as tracers, even at urban sites highly affected by traffic. [Copyright &y& Elsevier]

We analysed long-term datasets of ambient air concentrations of gaseous pollutants, black carbon (BC) and particle size distributions at an urban background air quality station (Barcelona, Spain; 2013–2019) and a regional background station (Montseny, Spain; 2014–2019). Using BC as a tracer of primary emissions, we segregated the aerosol load in modes and analysed their trends, considering all-year data and seasons separately. We also applied the positive matrix factorisation (PMF) receptor model to the particle size distributions to identify different sources that contribute to the particle number concentration. Our results show that the number concentration of primary particles decreased at the urban and regional background stations (−4.1 and −4.7% per year, respectively) along the period of study. This decrease was also observed for primary particles in the nucleation, Aitken and accumulation modes separately. This change leads to a decrease in condensation sinks (CS, −3.1 and −5.6% per year), that, together with an increase in temperatures (+1.5% per year in the urban background; +1.4% per year in the regional background), results in a markedly increasing trend in the contribution of new particle formation to the total number particle concentration (+17.7% and +11.9% per year). The total particle number concentration decreased in the urban background (−2.5% per year), whereas the trend increased for the regional background (+3.0% per year). The latter result is in contrast to most literature reports and is most likely due to higher insolation and increased biogenic VOC (BVOC) emissions that would enhance photonucleation, along with a marked decrease in the CS. An increasing trend in H 2 SO 4 concentrations driven by increasing SO 2 concentrations (+11.1% per year) could also be favouring the formation of new particles in the regional background, but it is not clear that the increasing trend in SO 2 is real or it is related to a faulty maintenance of the instrumentation. Overall, we conclude that decreasing primary emissions results in a decrease in the total number concentrations of urban aerosols, despite the increase in the formation of new particles by photonucleation. Moreover, the total particle number concentration of regions downwind of the urban areas increases because new particle formation is more favoured and compensates for the primary particles' number concentration decrease. • Decreasing traffic emissions in cities could favour photonucleation in high-insolated rural areas. • We measured gaseous pollutants, black carbon and particle size distributions. • We statistically analysed trends and applied positive matrix factorisation receptor modelling. • Reducing emissions in cities increases the number of particles in nearby rural areas. • Policies aimed at improving air quality in cities may negatively affect nearby rural regions. [ABSTRACT FROM AUTHOR]

Biomass burning is a major air pollution problem all around the world. However, the identification and quantification of its contribution to ambient aerosol levels is a difficult task due to the generalized lack of observations of molecular markers. This paper presents the results of a yearlong study of organic constituents of the atmospheric aerosol at a rural site in southern Spain (Villanueva del Arzobispo, Jaén). Sampling was performed for PM 10 and PM 2.5 , and a total of 116 and 115 samples, respectively, were collected and analyzed by GC/MS, quantifying 77 organic compounds. Higher levels of organic pollutants were recorded from November to March, coinciding with the cold season when domestic combustion is a common practice in rural areas. This jointly with adverse meteorological conditions, e.g. strong atmospheric stability, produced severe pollution episodes with high PM x ambient levels. High daily concentrations of tracers were reached, up to 26 ng m−3 for B(a)P and 6065 ng m−3 for levoglucosan in PM 2.5 , supporting that biomass burning is a major source of pollution at rural areas. A multivariate statistical study based on factor and cluster analysis, was applied to the data set with the aim to distinguish sources of organic compounds. The main resulting sources were related with biomass combustion, secondary organic aerosol (SOA), biogenic emissions, lubricating oil and soil organic components. A preliminary organic source profile for olive wastes burning was evaluated, based on cluster results, showing anhydrosacharides and xylitol are the main emitted compounds, accounting for more than 85% of the quantified compounds. Other source compounds were fatty acids, diacids, aliphatics, sugars, sugar alcohols, PAHs and quinones. • Air pollution exceeds PM10 & PM2.5 limit values in Spanish rural areas in winter. • GC/MS characterization of 77 polar and apolar organic compounds. • Daily concentrations up to 26 ng m−3 of Benzo(a)pyrene were reached. • Biomass burning was identified as the main source of many organic compounds. • Other sources were biogenic emissions, SOA, soil dust and lubricating oil. [ABSTRACT FROM AUTHOR]

This study addressed the scarcity of NH 3 measurements in urban Europe and the diverse monitoring protocols, hindering direct data comparison. Sixty-nine datasets from Finland, France, Italy, Spain, and the UK across various site types, including industrial (IND, 8), traffic (TR, 12), urban (UB, 22), suburban (SUB, 12), and regional background (RB, 15), are analyzed to this study. Among these, 26 sites provided 5, or more, years of data for time series analysis. Despite varied protocols, necessitating future harmonization, the average NH 3 concentration across sites reached 8.0 ± 8.9 μg/m 3 . Excluding farming/agricultural hotspots (FAHs), IND and TR sites had the highest concentrations (4.7 ± 3.2 and 4.5 ± 1.0 μg/m 3 ), followed by UB, SUB, and RB sites (3.3 ± 1.5, 2.7 ± 1.3, and 1.0 ± 0.3 μg/m 3 , respectively) indicating that industrial, traffic, and other urban sources were primary contributors to NH 3 outside FAH regions. When referring exclusively to the FAHs, concentrations ranged from 10.0 ± 2.3 to 15.6 ± 17.2 μg/m 3 , with the highest concentrations being reached in RB sites close to the farming and agricultural sources, and that, on average for FAHs there is a decreasing NH 3 concentration gradient towards the city. Time trends showed that over half of the sites (18/26) observed statistically significant trends. Approximately 50 % of UB and TR sites showed a decreasing trend, while 30 % an increasing one. Meta-analysis revealed a small insignificant decreasing trend for non-FAH RB sites. In FAHs, there was a significant upward trend at a rate of 3.51[0.45,6.57]%/yr. Seasonal patterns of NH 3 concentrations varied, with urban areas experiencing fluctuations influenced by surrounding emissions, particularly in FAHs. Diel variation showed differing patterns at urban monitoring sites, all with higher daytime concentrations, but with variations in peak times depending on major emission sources and meteorological patterns. These results offer valuable insights into the spatio-temporal patterns of gas-phase NH 3 concentrations in urban Europe, contributing to future efforts in benchmarking NH 3 pollution control in urban areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: The recent evidence of the short-term impact of air pollution on youth cognitive functions is based primarily on observational studies., Objectives: We conducted a randomized controlled trial to assess whether purifying the air of the classrooms produced short-term changes in attention processes of adolescents., Methods: We recruited a total of 2,123 adolescents (13-16 years old) in 33 high schools in Barcelona metropolitan area (Spain). In each school, adolescents from each class were randomly split into two equal-sized groups and assigned to two different classrooms. A set of two air cleaner devices with the same appearance (one recirculating and filtrating the air and the other only recirculating the air) was used. Each one of the devices was placed at random at one of the two classrooms. Students were masked to intervention allocation and had to complete several computerized activities for 1.5 h, including an attention test (Flanker task) to be performed at baseline and at the end of the intervention. The response speed consistency, expressed as hit reaction time standard error (HRT-SE, in ms), was measured as the primary outcome. Analyses were conducted using conditional linear regressions with classroom as strata, adjusted for variables that may differ from one class to another such as temperature, humidity and carbon dioxide concentration., Results: Average levels of PM 2.5 and black carbon throughout the 1.5 h of experiment were 89% and 87%, respectively, lower in the classrooms with air cleaner than in the control classrooms. No differences were found in the median of HRT-SE between classrooms with cleaned air and normal air (percent change: 1.37%, 95% confidence interval: -2.81%, 5.56%). Sensitivity analyses with secondary attention outcomes resulted in similar findings., Conclusions: Cleaning the air of a classroom to reduce exposure to air pollutants for 1.5 h did not have an impact on the attention function of adolescents. Still, in light of previous evidence suggesting an association between air pollution and attention, further experimental studies should explore other short-term timescales of exposure and age ranges., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Portable miniaturised scanning mobility particle sizer (SMPS) instruments measuring atmospheric particles within the 10-241 nm size range were used to track particle number size distributions and concentrations during near-simultaneous pedestrian, bicycle, bus, car, tram and subway commuting journeys in Barcelona, Spain on 4th-6th July 2018. The majority of particles in this size range were <100 nm, with k-means cluster analysis identifying peaks at 15-22 nm, 30-40 nm, and 45-75 nm. Around 10-25% of the particles measured however were >100 nm (especially in the subway environment) and so lie outside the commonly defined range of "ultrafine" particles (UFP, or <100 nm particles). The study demonstrated in detail how personal exposure to quasi-UFP (QUFP, <241 nm), most of which present in the city streets are produced by road traffic, varies greatly depending on the transport mode and route chosen. Proximity to fresh traffic exhaust sources, such as in a car with open windows, on-road cycling, walking downwind of busy roads, or in a subway station contaminated by roadside air, enhances commuter exposure to particles <30 nm in size. In contrast, travelling inside air-conditioned bus or tram offers greater protection to the commuter from high concentrations of fresh exhaust. Ultrafine number size distributions in traffic-contaminated city air typically peak in the size range 30-70 nm, but they can be shifted to finer sizes not only by increased content of fresh proximal exhaust emissions but also by bursts of new particle formation (NPF) events in the city. One such afternoon photochemical nucleation NPF event was identified during our Barcelona study and recognised in different transport modes, including underground in the subway system. The integration of static urban background air monitoring station information with particle number concentration and size distribution data obtained from portable miniaturised SMPS instruments during commuting journeys opens new approaches to investigating city air quality by offering a level of detail not previously available., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Airborne particulate matter with an aerodynamic diameter smaller than 2.5 µg, PM 2.5 was regularly sampled in classrooms (indoor) and playgrounds (outdoor) of primary schools from Barcelona. Three of these schools were located downtown and three in the periphery, representing areas with high and low traffic intensities. These aerosols were analyzed for organic molecular tracers and polycyclic aromatic hydrocarbons (PAHs) to identify the main sources of these airborne particles and evaluate the air quality in the urban location of the schools. Traffic emissions were the main contributors of PAHs to the atmospheres in all schools, with higher average concentrations in those located downtown (1800-2700 pg/m 3 ) than in the periphery (760-1000 pg/m 3 ). The similarity of the indoor and outdoor concentrations of the PAH is consistent with a transfer of outdoor traffic emissions to the indoor classrooms. This observation was supported by the hopane and elemental carbon concentrations in PM 2.5 , markers of motorized vehicles, that were correlated with PAHs. The concentrations of food-related markers, such as glucoses, sucrose, malic, azelaic and fatty acids, were correlated and were higher in the indoor atmospheres. These compounds were also correlated with plastic additives, such as phthalic acid and diisobutyl, dibutyl and dicyclohexyl phthalates. Clothing constituents, e.g., adipic acid, and fragrances, galaxolide and methyl dihydrojasmonate were also correlated with these indoor air compounds. All these organic tracers were correlated with the organic carbon of PM 2.5 , which was present in higher concentrations in the indoor than in the outdoor atmospheres.

Recently, there has been a flurry of publications assessing the effect of air pollution on neurodevelopment. Here we present a summary of the results obtained within the BRain dEvelopment and Air polluTion ultrafine particles in scHool childrEn (BREATHE) Project, which aimed to evaluate the effects of the exposure to traffic related air pollutants in schoolchildren in Barcelona. To this end, we comprehensively characterised air quality in 39 urban schools from Barcelona and identified the main determinants of children's increased exposure. We propose a series of measures to be implemented to improve air quality in schools within the urban context and, consequently, minimise the negative effects on children's neurodevelopment that we found to be associated with the exposure to air pollution. We also aimed to list some of the actions pushed by governments and the society (including school managers, parents, and children) that have been taking place around Europe for promoting better high quality in the school and its surroundings., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Traffic-related air pollution is emerging as a risk factor for Alzheimer's disease (AD) and impaired brain development. Individual differences in vulnerability to air pollution may involve the ε4 allele of Apolipoprotein E ( APOE ) gene, the primary genetic risk factor for AD., Objective: We analyzed whether the association between traffic air pollution and neurodevelopmental outcomes is modified by APOE ε4 status in children., Methods: Data on parent-reported behavior problems (total difficulties scores, Strengths and Difficulties Questionnaire), teacher-reported attention-deficit hyperactivity disorder (ADHD) symptom scores, cognitive performance trajectories (computerized tests of inattentiveness and working memory repeated 2-4 times during January 2012-March 2013), and APOE genotypes were obtained for 1,667 children age 7-11 y attending 39 schools in or near Barcelona. Basal ganglia volume (putamen, caudate, and globus pallidum) was measured in 163 of the children by MRI (October 2012-April 2014.) Average annual outdoor polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), and nitrogen dioxide (NO 2 ) concentrations were estimated based on measurements at each school (two 1-wk campaigns conducted 6 months apart in 2012)., Results: APOE ε4 allele carriers had significantly higher behavior problem scores than noncarriers, and adverse associations with PAHs and NO 2 were stronger or limited to ε4 carriers for behavior problem scores ( P -interaction 0.03 and 0.04), caudate volume ( P -interaction 0.04 and 0.03), and inattentiveness trajectories ( P -interaction 0.15 and 0.08, respectively). Patterns of associations with the same outcomes were similar for EC., Conclusion: PAHs, EC, and NO 2 were associated with higher behavior problem scores, smaller reductions in inattentiveness over time, and smaller caudate volume in APOE ε4 allele carriers in our study population, and corresponding associations were weak or absent among ε4 noncarriers. These findings support a potential role of APOE in biological mechanisms that may contribute to associations between air pollution and neurobehavioral outcomes in children. https://doi.org/10.1289/EHP2246.

Objective: To assess the relationship between short-term exposure to outdoor ambient air pollutants (fine particulate matter [PM 2.5 ] and black carbon [BC]), ischemic stroke (IS) and its different subtypes, and the potential modifying effect of neighborhood greenspace and noise., Methods: This time-stratified case-crossover study was based on IS and transient ischemic attacks (TIA) recorded in a hospital-based prospective stroke register (BASICMAR 2005-2014) in Barcelona (Catalonia, Spain). Daily and hourly pollutant concentrations and meteorological data were obtained from monitoring stations in the city. Time-lags (from previous 72h to acute stroke onset) were analyzed. Greenness and noise were determined from the Normalized Difference Vegetation Index (NDVI) and daily average noise level at the street nearest to residential address, respectively., Results: The 2742 cases with known onset date and time, living in the study area, were analyzed. After adjusting for temperature, no statistically significant association between pollutants exposure and overall stroke risk was found. In subtype analysis, an association was detected between BC exposure at 24-47h (odds ratio, 1.251; 95% confidence interval [CI], 1.001-1.552; P = 0.042) and 48-72h (1.211; 95% CI, 0.988-1.484; P = 0.065) time-lag prior to stroke onset and large-artery atherosclerosis subtype. No clear modifying effect of greenness or noise was observed., Conclusions: Overall, no association was found between PM 2.5 and BC exposure and acute IS risk. By stroke subtype, large-artery atherosclerotic stroke could be triggered by daily increases in BC, a diesel fuel-related pollutant in the study area., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)