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Abstract: Introduction: An analysis of the hourly SO2 pollution patterns with time can be a useful tool for policy makers and stakeholders in developing more effective local policies in relation to air quality as it facilitates a deeper understanding of concentrations and potential source apportionment. A detailed analysis of hourly inter-annual, seasonal and weekday-specific SO2 concentration patterns using data obtained from 6 cities involved in the Aphekom project was conducted. This type of analysis has been done for other pollutants but less so for SO2, and not in a systematic fashion for a number of European cities. Methods: Individual diurnal SO2 profiles and working weekday versus weekend specific 24-hr plots were generated using hourly SO2 measurements from a roadside and an urban background monitoring sites for 1993, 2001 and 2009 for each of the 6 European cities (Athens, Barcelona, Brussels, London, Paris, and Vienna). This facilitated the assessment of city specific patterns and comparison of changes with time. Results: SO2 concentrations varied throughout the day and tended to be lower on the weekends. A general decreasing trend for SO2 levels with time was observable at all stations. Discussion & Conclusion: This study provides a useful European perspective on patterns of exposure. For the 6 EU cities examined, road traffic, heating, and shipping in port cities appeared to be important sources of SO2 emissions, and hence the driving components widely reflected in the diurnal profiles with lower levels on the weekend likely due to lower traffic volume and industry related emissions. Although ambient SO2 concentrations have fallen over the assessed study period at all measurement sites, the daily patterns remained relatively unchanged. [Copyright &y& Elsevier]

Abstract: Simultaneous measurements of the PM concentration levels and chemical composition of atmospheric aerosols at a regional background (RB) and an urban background (UB) site, located in the same geographic region, allowed for the determination of their urban and regional contributions. In the specific case of the North-Western region of the Mediterranean the RB amount has been quantified in 18, 13 and 12 μg m−3 for PM10, PM2.5 and PM1, respectively, whereas the UB contribution reached 22, 13 and 8 μg m−3, respectively. The UB contributions in the Western Mediterranean are much higher than those observed in other European regions; especially concerning the coarse fraction. The high loads of road dust in the urban areas across the Mediterranean may account for these large differences. The urban contributions are extremely enriched in Ca, Fe, Sb, Sn, Cu, Zn, being the main tracers of the road dust, with concentrations up to 6–8 times higher than those at the RB. Elemental carbon and nitrate are mainly derived from direct vehicular emissions. Some industrial tracers (Mn, Pb, Bi) are also enriched in the urban area. The evaluation of the Cu/Sb, Cu/Zn, Cu/Cd and Cu/Pb ratios and the high enrichment of these trace elements versus the Upper Crustal Composition average values corroborates the importance of the road-traffic emissions in the study area, also influencing the RB. The supplementary results from a suburban site in the Balearic Islands and the evaluation of the V/Ni ratios evidence the strong signature of fuel-oil combustion processes, which is a general characteristic of the Mediterranean aerosols. [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: The majority of the Spanish urban population breathe air containing inhalable ambient airborne particles at average concentrations of 30–46μgm−3 (PM10) and 20–30μgm−3 (PM2.5). Even though the average weight of inhaled urban aerosol is commonly similar, however, there can be large chemical differences between the ambient dusts from different towns, including the more bioreactive elements such as some metals. In this context, we compare the source-apportioned trace metal content of airborne PM10 and PM2.5 collected daily over a 1-year period from six population centres in Spain: Barcelona, Alcobendas, Llodio, Huelva, Tarragona and Las Palmas de Gran Canaria. Total average trace metal (ΣTM) PM10 and PM2.5 contents vary by up to a factor of around 3, reaching a maximum of ΣTM10 811ngm−3 and ΣTM2.5 503ngm−3 at Llodio, an industrial but humid site with the lowest PM10 mass levels but high contamination by Zn, Pb, Mn, Sn, Ni and Cr. In contrast, pollution at Huelva, although another industrially influenced site, instead emphasises Cu and As, whereas Barcelona, where traffic emissions and resuspension contribute to some of the highest average PM10 levels in Spain, has unusually raised levels of Ti, V and Ba. Such variations in both daily and annual average PM bulk chemistry, particularly in potentially toxic trace metals concentrated in the finer aerosols (such as Cd, As, Pb, Hg and Ni), predict that PM health effects on resident populations from different towns are unlikely to be the same. [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]

Abstract: A strong African dust outbreak episode affecting the Canary Islands from 28 to 31/07/02 has been characterised at the Izaña Observatory (IZO), located in the free troposphere (FT), and at Sta. Cruz de Tenerife (SCO), in the Marine Boundary Layer (MBL). The Saharan air mass intruded above the trade wind inversion layer resulting in daily mean PM levels of up to 616, 312, 98 and 26μgm−3 of TSP, PM10, PM2.5 and PM1, respectively, at IZO. As demonstrated by the vertical sounding profiles, the MBL is compressed during the Saharan intrusion, favouring the deposition of coarse dust particles to the MBL and giving rise to daily levels of up to 85, 52 and 30μgm−3 of PM10, PM2.5 and PM1, respectively, at SCO. A complete chemical and mineralogical characterisation has been performed for TSP and PM2.5 collected simultaneously at both sites. Levels of mineral elements increased during the Saharan episode at both sampling sites. In addition, at the MBL, the levels of the secondary inorganic aerosols registered during the Saharan episode were considerably higher than levels recorded during non-Saharan episodes. The partial formation of secondary coarse Ca and/or Na sulphates and nitrates by the reaction of gaseous pollutants (or derived oxidised phases), of a major local origin, with the natural aerosols has been deduced. These reactions may be favoured by the high concentration of coarse mineral and marine aerosols particles measured at SCO, the high relative humidity (RH) measured, as well as the strong compression of the MBL during the Saharan episode. [Copyright &y& Elsevier]

A detailed physical and chemical characterisation of total suspended particles (TSP) in the highly industrialised city of Huelva (southwestern Spain) was carried out. The results evidenced a coarse grain-size prevalence (PM10 accounting for only 40% of TSP mass, 37 and 91 μg/m3, respectively). PM10 levels are in the usual range for urban background sites in Spain. The crustal, anthropogenic and marine components accounted for a mean of a 40%, 24% and 5% of bulk TSP, respectively. As expected from the industrial activities, relatively high PO43− and As levels for an urban site were detected. In addition to the crustal and marine components, source apportionment analysis revealed three additional emission sources influencing the levels and composition of TSP: (a) a petrochemical source, (b) a mixed metallurgical-phosphate source, (c) and an unknown source (Sb and NO3−).Due to the high local emissions, the mean TSP anthropogenic contribution (mostly PM10) obtained for all possible air mass transport scenarios reached 18–29 μg/m3. The 2010 annual EU PM10 limit value (20 μg/m3) would be exceeded by the anthropogenic load recorded for all the air mass transport scenarios, with the exception of the North Atlantic transport (only 15% of the sampling days). Under African air mass transport scenarios (20% of sampling days), the TSP crustal contribution reached near three times the local crustal contribution. It must be pointed out that this crustal input should diminish when sampling PM10 due to the dominant coarse size distribution of this type of particles. [Copyright &y& Elsevier]

Concentrations of airborne particulates undergo a seasonal evolution characterised by a summer maximum in rural areas in Eastern Spain. In the summer months the daily mean concentrations of PM10 and TSP (PM) experience wide variations. In 3-day periods, increases in the PM concentrations from 15 to 30–40 μg/m3 are frequently reported, and increases from 15 to 40–60 μg/m3 occur several times throughout the summer. These variations are simultaneously reported at rural stations throughout the flat Ebro basin (600 m a.s.l.) and at mountain sites located at high altitude (>1000 m a.s.l.). The origin of high and low PM episodes was investigated by correlating PM levels with the concentrations of gaseous pollutants, and making use of meteorological analysis and satellite observations. The highest PM events (daily concentrations in the range 40–60 μg/m3) were documented during outbreaks of African dust. The second highest PM events (daily concentrations in the range 20–45 μg/m3) were recorded during regional episodes associated with ozone events. These summer regional PM episodes were induced by the abrupt orography surrounding the Western Mediterranean and by the regional meteorology, which favour the ageing of polluted air masses into the basin. These regional events occur in a synoptic meteorological context characterised by a weak pressure horizontal gradient over the Western Mediterranean often associated with the development of the Iberian thermal low, when advection of air masses is not significant. In this meteorological context, the transport of particulate pollutants from urban/industrial to rural sites is brought about by the breeze circulation at the coastal (sea breeze) and mountain (mountain breeze) sites. The persistence of this breeze circulation for several days (periods of up to 2 weeks were reported) results in a low renovation of air masses leading to an accumulation of airborne particulates in the regional atmosphere. The lowest PM events (daily concentrations <20 μg/m3) were reported during abrupt entries of Atlantic air into the Mediterranean. [Copyright &y& Elsevier]

In this work, PM2.5 samples were collected in the winter-spring months of 2014–2016 at an urban site in Córdoba. Córdoba is the second largest city in Argentina and is an important industrial and touristic center. The collected samples were individually analyzed for chemical composition using different techniques. The soluble inorganic ions and carbonaceous particles were determined from bulk aerosol samples for the first time in the city. The mass concentrations of PM2.5, organic carbon, elemental carbon, inorganic ions and metals were determined according to the mass balance. The dominant mass components were organic matter and elemental carbon (54.8%), mineral dust (6.1%), secondary inorganic aerosols (3.0%), and salt (1.2%). A principal component analysis was applied to the samples and resulted in five major factors that explained 79% of the variance in PM2.5. These factors represented combustion, industrial sources, soil dust, secondary inorganic aerosol, and salt, and each explained between 11% and 20% of the variance. A comparison with the results from a previous campaign (2010–2011) revealed appreciable changes in the PM2.5 chemical composition. These changes were attributed to the two extreme meteorological conditions that prevailed in the region. The years 2014–2016 were largely dominated by the warm phase of the El Niño–Southern Oscillation, which leads to humid and cold weather in the Córdoba region, while the samples from 2010 to 2011 were collected during the dry and hot years resulting from the La Niña regime. [ABSTRACT FROM AUTHOR]

Many cities still exceed the European Union (EU) air quality limit values for particulate matter (PM 10 , particles with an aerodynamic diameter less than 10 μm) and/or nitrogen dioxide (NO 2 ). In an attempt to reduce emissions approximately 200 low emission zones (LEZs) have been established in 12 EU countries. These restrict the entry of vehicles based on the emission standard the vehicles were originally constructed to meet, but the restrictions vary considerably. This paper reviews the evidence on the efficacy of LEZs to improve urban air quality in five EU countries (Denmark, Germany, Netherlands, Italy and UK), and concludes that there have been mixed results. There is some evidence from ambient measurements that LEZs in Germany, which restrict passenger cars as well as heavy duty vehicles (HDVs), have reduced long term average PM 10 and NO 2 concentrations by a few percent. Elsewhere, where restrictions are limited to HDVs, the picture is much less clear. This may be due to the large number of confounding factors. On the other hand there is some, albeit limited, evidence that LEZs may result in larger reductions in concentrations of carbonaceous particles, due to traffic making a larger contribution to ambient concentrations of these particles than to PM 10 and PM 2.5 . The effects of day to day variations in meteorology on concentrations often mask more subtle effects of a LEZ. In addition, separating the direct effects of a LEZ from the effects of other policy measures, the economy and the normal renewal of the vehicle fleet is not easy, and may give rise to false results. [ABSTRACT FROM AUTHOR]

Abstract: The present work shows a straightforward procedure to indirectly estimate the chemical composition at a given site only from the determination of the PM concentrations, and the classification of the days according to the main meteorological scenarios. A previous study based on the mean chemical composition associated to the main meteorological scenarios is required. This experiment has been carried out with data from two monitoring sites in the North-Western Mediterranean, one regional and one suburban background. At both sites, one-year datasets on chemical PM10 composition were obtained. Based on these datasets, the mean PM10 compositions according to the most relevant meteorological situations were calculated for both locations. After that, the reconstruction of the chemical composition for all the days with available PM10 concentrations was completed. Subsequently, the estimated PM10 composition was compared with that determined experimentally. The comparison between the rebuilt and the experimental results was very satisfactory in the case of the regional background site, and relatively replaced in the other case. Furthermore, the validation of the method at the regional background site has been conducted from the reconstruction of a 4-year data base, and subsequent comparison with the experimental chemical composition. Our results show that it is possible to attain a good approach to the chemical composition at regional background sites, where local emission sources are negligible. Conversely, when the local sources rise in importance, i.e., at a suburban background site, the approach is suitable only for those components with a more regional origin and/or those from long range transport of air masses. [ABSTRACT FROM AUTHOR]

Abstract: Different monitoring parameters (PM mass concentrations, number–size distribution, black carbon, gaseous pollutants, and chemical composition, among others) are currently used in air quality studies. Urban aerosols are the result of several sources and atmospheric processes, which suggests that a single monitoring technique is insufficient to quantitatively evaluate all of them. This study assesses the suitability of a number of monitoring techniques (PM mass concentrations, number and size distribution of ultra-fine particles, levels of gaseous pollutants, and a complete chemical characterization of PM10 and PM2.5) by examining the response of those techniques to the different emission sources and/or atmospheric processes affecting an urban Mediterranean area (Barcelona, NE Spain). The results of this work reveal that the PM mass, the number concentration and the chemical composition give different, but complementary, information. Whereas the mineral matter, a key atmospheric aerosol component across the Mediterranean, is not properly quantitatively assessed by measuring sub-micrometric particles, the monitoring of the number concentration is indispensable to interpret the origin of specific aerosol episodes. Furthermore, the chemical composition yields very relevant information to deduce the causes of specific pollution episodes. The number concentration of ultra-fine particles in urban areas is strongly dependent upon vehicle exhaust emissions, which may cause adverse health impacts. Moreover, urban Mediterranean environments are favourable to produce nucleation-mode particles (<20 nm) with photochemical origin. In those cases, these particles are expected to be of high solubility and consequently their toxicity may differ from that of traffic-generated ultra-fine particles. Thus, the use of a single monitoring parameter to evaluate the health effects seems to be not enough. [ABSTRACT FROM AUTHOR]

Abstract: The geochemistry of PM10 filter samples collected at sea during the Scholar Ship Atlantic–Mediterranean 2008 research cruise reveals a constantly changing compositional mix of pollutants into the marine atmosphere. Source apportionment modelling using Positive Matrix Factorization identifies North African desert dust, sea spray, secondary inorganic aerosols, metalliferous carbon, and V–Ni-bearing combustion particles as the main PM10 factors/sources. The least contaminated samples show an upper continental crust composition (UCC)-normalised geochemistry influenced by seawater chemistry, with marked depletions in Rb, Th and the lighter lanthanoid elements, whereas the arrival of desert dust intrusions imposes a more upper crustal signature enriched in “geological” elements such as Si, Al, Ti, Rb, Li and Sc. Superimposed on these natural background aerosol loadings are anthropogenic metal aerosols (e.g. Cu, Zn, Pb, V, and Mn) which allow identification of pollution sources such as fossil fuel combustion, biomass burning, metalliferous industries, and urban–industrial ports. A particularly sensitive tracer is La/Ce, which rises in response to contamination from coastal FCC oil refineries. The Scholar Ship database allows us to recognise seaborne pollution sourced from NW Africa, the Cape Verde and Canary islands, and European cities and industrial complexes, plumes which in extreme cases can produce a downwind deterioration in marine air quality comparable to that seen in many cities, and can persist hundreds of kilometres from land. [Copyright &y& Elsevier]

Abstract: We report on ambient atmospheric aerosols present at sea during the Atlantic–Mediterranean voyage of Oceanic II (The Scholar Ship) in spring 2008. A record was obtained of hourly PM10, PM2.5, and PM1 particle size fraction concentrations and 24-h filter samples for chemical analysis which allowed for comparison between levels of crustal particles, sea spray, total carbon, and secondary inorganic aerosols. On-board monitoring was continuous from the equatorial Atlantic to the Straits of Gibraltar, across the Mediterranean to Istanbul, and back via Lisbon to the English Channel. Initially clean air in the open Atlantic registered PM10 levels <10 μg m−3 but became progressively polluted by increasingly coarse PM as the ship approached land. Away from major port cities, the main sources of atmospheric contamination identified were dust intrusions from North Africa (NAF), smoke plumes from biomass burning in sub-Saharan Africa and Russia, industrial sulphate clouds and other regional pollution sources transported from Europe, sea spray during rough seas, and plumes emanating from islands. Under dry NAF intrusions PM10 daily mean levels averaged 40–60 μg m−3 (30–40 μg m−3 PM2.5; c. 20 μg m−3 PM1), peaking briefly to >120 μg m−3 (hourly mean) when the ship passed through curtains of higher dust concentrations amassed at the frontal edge of the dust cloud. PM1/PM10 ratios ranged from very low during desert dust intrusions (0.3–0.4) to very high during anthropogenic pollution plume events (0.8–1). [Copyright &y& Elsevier]

Abstract: Average 21st century concentrations of urban air pollutants linked to cardiorespiratory disease are not declining, and commonly exceed legal limits. Even below such limits, health effects are being observed and may be related to transient daytime peaks in pollutant concentrations. With this in mind, we analyse >52,000 hourly urban background readings of PM10 and pollutant gases throughout 2007 at a European town with legal annual average concentrations of common pollutants, but with a documented air pollution-related cardiorespiratory health problem, and demonstrate the hourly variations in PM10, SO2, NOx, CO and O3. Back-trajectory analysis was applied to track the arrival of exotic PM10 intrusions, the main controls on air pollutants were identified, and the typical hourly pattern on ambient concentrations during 2007 was profiled. Emphasis was placed on “worst case” data (>90th percentile), when health effects are likely to be greatest. The data show marked daytime variations in pollutants result from rush-hour traffic-related pollution spikes, midday industrial SO2 maxima, and afternoon O3 peaks. African dust intrusions enhance PM10 levels at whatever hour, whereas European PM incursions produce pronounced evening peaks due to their transport direction (across an industrial traffic corridor). Transient peak profiling moves us closer to the reality of personal outdoor exposure to inhalable pollutants in a given urban area. We argue that such an approach to monitoring data potentially offers more to air pollution health effect studies than using only 24 h or annual averages. [Copyright &y& Elsevier]

Real time measurements of number concentrations (13–800 nm, N13–800) of size discriminated sub-micrometric aerosols and PM (0.3–10 μm) mass concentrations were carried out over a one-year-period at an urban site in Barcelona, North-eastern Spain. Annual mean levels of N13–800 were close to 17,000 cm−3, and strongly dependent on road traffic emissions. Annual mean PM10, PM2.5 and PM1 levels were 39, 25 and 18 μg/m3, being highly influenced not only by road traffic but also by industrial emissions as well as natural events such as African dust outbreaks. Variability of number concentrations and size distribution of sub-micrometric aerosols was strongly dependent on meteorology. Primary emissions exert a high influence on the variability of levels of ultrafine (<100 nm) particles under intense Atlantic advections (lowest PM levels), while coagulation and condensation processes are enhanced under urban pollution scenarios (highest levels of PM), and photochemical nucleation processes can be an important source of ultrafine particles at midday in summer (low PM levels). African dust episodes did not modify the total number but affected the N > 400 nm. This study allows us to compare aerosol number and mass concentrations in air quality monitoring of an urban environment. Ultrafine particles measurements are indicated to detect the variability of primary traffic emissions, as well as some atmospheric processes. Measurements of PM levels are necessary to monitor other important PM sources in the studied area such as dust resuspension from road traffic or African dust. [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]

This study examined the variability and source of carbonaceous aerosols, encompassing total carbon (TC), organic carbon (OC), and secondary organic carbon (SOC) for the years 2019–2020, as well as equivalent black carbon (eBC) and equivalent ultraviolet BC (eUVBC) data spanning 2019–2022, in the context of a typical northern Chinese city: Yanzhou. Averaged concentrations of TC, OC, SOC, eBC, eUVBC, and the ratio (OC/elemental carbon (EC)) reached 11.1 ± 6.7, 8.9 ± 5.1, 3.9 ± 2.0, 3.1 ± 1.3, and 4.3 ± 2.4 μg/m3, and 5.0 ± 2.2, respectively. The concentrations of TC, OC, eBC, and eUVBC were higher in winter, followed by spring and autumn, and summer, while SOC presented the opposite seasonal patterns. The diurnal variations of TC, OC, eBC, and eUVBC exhibited a bimodal pattern with peaks in the early morning (08:00–09:00 LT) and late evening (00:00–01:00 LT) and a trough in the afternoon (14:00–16:00 LT), pointing to vehicular emission and meteorological dispersion as major drivers of the hourly variability. The results obtained from the EC tracer method and minimum R squared (MRS) revealed that r(SOC/OC) were highest in summer (60%) and lowest in winter (26%), showing a fast summer photochemical oxidation of volatile organic compounds (VOCs) that generate SOC. In this study, the influence of meteorological conditions on the weighting of diverse carbonaceous aerosols was quantified using a machine learning method. Results showed that the main drivers of carbonaceous aerosols were height of the planetary boundary layer (HPBL), ambient temperature (AT), relative humidity (RH), and atmospheric pressure (AP) in all seasons. Additionally, the potential health risks of eBC based on the equivalent passive smoking of cigarettes (PSC) suggested that there was a certain level of human health risk in this city. The obtained results will provide more in-depth and comprehensive understanding of carbonaceous aerosol pollution and management strategies. [Display omitted] • Online sampling of carbonaceous aerosols (CAs) was firstly assessed in Yanzhou. • The weight of SOC in OC was highest in summer (60%) and lowest in winter (26%). • HPBL, AT, RH, and AP are the driving factors for different CAs. • Increased eBC caused relatively high health risk to children. [ABSTRACT FROM AUTHOR]

Air quality in subway systems is of interest not only because particulate matter (PM) concentrations can be high, but also because of the peculiarly metalliferous chemical character of the particles, most of which differ radically from those of outdoor ambient air. We report on the oxidative potential (OP) of PM 2.5 samples collected in the Barcelona subway system in different types of stations. The PM chemical composition of these samples showed typically high concentrations of Fe, Total Carbon, Ba, Cu, Mn, Zn and Cr sourced from rail tracks, wheels, catenaries, brake pads and pantographs. Two toxicological indicators of oxidative activity, ascorbic acid (AA) oxidation (expressed as OP AA μg −1 or OP AA m −3 ) and glutathione (GSH) oxidation (expressed as OP GSH μg −1 or OP GSH m −3 ), showed low OP for all samples (compared with outdoor air) but considerable variation between stations (0.9–2.4 OP AA μg −1 ; 0.4–1.9 OP GSH μg −1 ). Results indicate that subway PM toxicity is not related to variations in PM 2.5 concentrations produced by ventilation changes, tunnel works, or station design, but may be affected more by the presence of metallic trace elements such as Cu and Sb sourced from brakes and pantographs. The OP assays employed do not reveal toxic effects from the highly ferruginous component present in subway dust. [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]

Water spraying and/or chemical suppressants such as salts and polymers have been suggested to reduce road dust resuspension due to their capability to increase adhesion, and therefore the effective size and weight of particles, but contrasting results have been obtained so further testing are needed. This study presents the first results of street washing and Calcium Magnesium Acetate (CMA) efficiencies at two industrial roads (paved and unpaved) in the Mediterranean region where the high solar radiation, warm climate, and scarce precipitation, may play a key role in determining the efficiency of mitigation techniques Results show that, at both sites, street washing (water only) was more effective than CMA. Street washing made observe 18% (daily basis) and >90% (first hour) reductions of kerbside PM10 concentrations for the paved and unpaved road respectively, while with CMA PM10 decrease was generally lower and with less statistical significance. [ABSTRACT FROM AUTHOR]

Road dust emission is an emerging issue in air quality due to the lack of remediation measures in contrast to vehicle exhaust emissions. The evidence of receptor modeling studies allows for quantifying impact on a few receptors, but the high cost of PM chemical speciation data and the questionable representativeness of single monitoring sites, limit considerably the development of population exposure estimates and epidemiologic studies based on georeferenced data. This study attempts to initiate and promote urban-scale dispersion modeling for road dust emissions, which will allow for a more robust estimate of population exposure and health outcomes. The TNO URBIS (URBan Information System) model was applied in the city of Barcelona, implementing a Gaussian line source and a street canyon dispersion model, together with new experimental estimates of road dust emission factors and algorithm to describe the time variability. Annual, daily and hourly road dust contributions were simulated and validated against observation of PM10, mineral dust and hourly PM2.5-10 concentrations. Results show that road dust contributed 9–15% to PM10 levels at background sites, and 23–44% at traffic sites. Highest contributions were modeled in the commercial/residential district where most of population live and work (Eixample) structured by 120 m wide square blocks, separated by roads with >10,000 vehicles per day. Street level contributions rise up to 20 μ g/m 3 (96% of roads) and an additional 3% of roads within 20–40 μ g/m 3 . Hourly simulations of road dust contributions revealed to benefit from the implementation of the new emission module ( Amato et al., 2012 ), able to describe the exponential recovery of road dust emission potential after rain events, when compared to common approach such as the use of constant emission factor or an ON/OFF approach. Correlation coefficients with observed data varied from 0.61, 0.58 and 0.43 for annual, daily and hourly means, respectively, revealing a clear improvement in terms of both spatial and temporal variability. However, more efforts need to be done in validating the model in different climatic scenarios and evaluating the seasonal variation of road dust emissions, due to droughts or Saharan dust events. [ABSTRACT FROM AUTHOR]

Legislation controlling vehicle emissions has been credited with a general downward trend in NO x (NO 2 +NO) concentrations in Europe since the 1990's. However, recent studies suggest that traffic (roadside) (TR) NO 2 concentrations have not decreased as expected, and in some cases increased, most likely due to the use of oxidation catalysts and particle filters in diesel vehicles (EURO III, IV, V, VI). In this study we describe the time trends in NO x , NO 2 and NO concentrations in 9 European cities comparing TR and urban background (UB) monitoring locations. In each city, we collected hourly city-specific NO x , NO, and NO 2 data from one TR and one UB monitoring site for each year. We describe hourly, weekly, seasonal and inter-annual patterns for periods corresponding to the implementation dates of various EURO vehicle emission standards regulating NO x emissions. The diurnal patterns in all 9 cities strongly reflected morning and evening traffic. In addition, lower weekend concentrations were observed. The NO x concentrations from the TR sites remain unchanged in the majority of the cities over the study period. When stratified by 3 time periods according to the implementation of the EURO standards, an increasing NO 2 /NO x ratio in 7/9 cities with time was noted. However, over the same time period the NO/NO 2 ratio decreased in 8/9 cities. A permanent inversion of the NO/NO 2 ratio was observed to occur in 2003 in 5/9 cities. Our analyses of temporal and diurnal patterns of NO x in European cities show reductions in concentrations consistent with reductions in primary emissions likely arising from the implementation of successive EURO standards. The generally constant or increasing NO 2 concentrations in the majority of the cities assessed over the study period underline the need of further regulative measures to meet the air quality standards and consequently to minimise adverse effects on human health. The ongoing collection and analysis of pollution concentrations across the EU is recommended to monitor trends in pollutants associated with adverse health effects. [ABSTRACT FROM AUTHOR]

This paper reports on results from a multi-sampling campaign (stack, fugitive emissions and ambient air measurements) to characterise the geochemical signature of metal and metalloid particles emitted from one of the largest Cu-smelters in the world (in Huelva, SW Spain). Exceptionally high concentrations of very fine particles (<0.33 μm) bearing As, Cd, Pb, Cu, Bi, Zn (∑>100 μg m −3 ) are emitted from the Flash Smelting Furnaces, but high levels are also emitted by the other main chimney stacks, namely Refining Furnaces, Sulphuric Plant, Converters Unit, and Crushing Plant. Enhanced concentrations of the same elements are also observed in ground measurements near the industrial complex. During the sampling campaign, the presence of plumes from the Cu-smelter over the nearby city of Huelva was identified based on increased concentrations of gaseous pollutants, particulate metals and ultrafine particle numbers (PN). The results demonstrate that the Cu-smelter is an important source of inhalable toxic elements carried by fine airborne particles. The pollution abatement systems applied so far appear to be relatively ineffective in preventing metalliferous air pollution events, potentially increasing health risks to local and regional populations. [ABSTRACT FROM AUTHOR]

Abstract: The chemical analysis of 553 school playground and classroom PM2.5 filters collected during the BREATHE sampling campaign in Barcelona, Spain, reveals a remarkable degree of spatial and temporal variability in ambient PM composition. Classroom air quality shows average PM2.5 concentrations of 37 μg m−3 (28% higher than outdoors), with much of this mass comprising carbon (including abundant cotton fibres), blackboard chalk particles and silicates. Where sandy playgrounds are present these exert a major influence on inhalable PM2.5 concentrations both indoors and outdoors. Throughout the city there is widespread contamination by metalliferous traffic particles, especially at schools located close to major urban highways where outdoor EC levels can be an order of magnitude higher than in peripheral, green belt schools. Penetration into the classroom of outdoor EC, ammonium sulphate and anthropogenic metals such as Cu, Sn, Sb, Zn and V is pervasive, especially during warmer months. In contrast, levels of nitrate and ammonium are much higher outdoors than in the classroom, especially during winter. During their work and play, schoolchildren across the city respire in a diversity of chemically differing atmospheric microenvironments. [Copyright &y& Elsevier]

Abstract: Shipping emissions are currently increasing and will most likely continue to do so in the future due to the increase of global-scale trade. Ship emissions have the potential to contribute to air quality degradation in coastal areas, in addition to contributing to global air pollution. With the aim to quantify the impacts of shipping emissions on urban air quality in coastal areas in Europe, an in depth literature review was carried out focussing on particulate matter and gaseous pollutants but also reviewing the main chemical tracers of shipping emissions, the particle size distribution of ship-derived particulates and their contributions to population exposure and atmospheric deposition. Mitigation strategies were also addressed. In European coastal areas, shipping emissions contribute with 1–7% of ambient air PM10 levels, 1–14% of PM2.5, and at least 11% of PM1. Contributions from shipping to ambient NO2 levels range between 7 and 24%, with the highest values being recorded in the Netherlands and Denmark. Impacts from shipping emissions on SO2 concentrations were reported for Sweden and Spain. Shipping emissions impact not only the levels and composition of particulate and gaseous pollutants, but may also enhance new particle formation processes in urban areas. [Copyright &y& Elsevier]

Abstract: Trace and major elements concentrations in PM10 and PM2.5 were measured at 20 sites spread in the Barcelona metropolitan area (1 rural background, 6 urban background, 13 road traffic sites) and at 1 reference site. Three 2-week samples per site and size fraction were collected during 2009 using low volume samplers, adding a total of 120 samples. Collected samples were analysed for elemental composition using Energy Dispersive X-ray fluorescence (XRF). EC, OC, and hopanes and steranes concentrations in PM2.5 were determined. Positive Matrix Factorisation (PMF) model was used for a source apportionment analysis. The work was performed as part of the ESCAPE project. Elements were found in concentrations within the usual range in Spanish urban areas. Mineral elements were measured in higher concentrations during the warm season, due to enhanced resuspension; concentrations of fueloil combustion elements were also higher in summer. Elements in higher concentration at the traffic sites were: Ba, Cr, Cu, Fe, Mn, Mo, Pb, Sn, Zn and Zr. Spatial variations related to non-traffic sources were observed for concentrations of Br, Cl, K, and Na (sea salt origin) and Ni, V and S (shipping emissions), which were higher at the coastal sites, as well as for Zn and Pb, higher at sites closer to industrial facilities. Five common sources for PM10 and PM2.5 were identified by PMF: road traffic (with tracers Ba, Cr, Cu, Fe, Mo and Zn); fueloil combustion (Ni and V); secondary sulphate; industry (Pb and Zn); and mineral source (Al, Ca, Mg, Si, Sr and Ti). A marine aerosol source, a mixture of sea salt with aged anthropogenic aerosols, was found only in PM10. EC, hopanes and steranes concentrations correlate strongly with the PM10 road traffic source contributions, being hence all attributed to the same source. OC may arise from other sources in addition to road traffic and have a high contribution of secondary OC. Significant spatial and temporal variation in the PM2.5 and PM10 elemental composition was found. Spatial patterns differed per element, related to the main source. The identified source contributions can be used in health studies of source-specific particles. [Copyright &y& Elsevier]

Abstract: Wildfires produce a significant release of gases and particles affecting climate and air quality. In the Mediterranean region, shrublands significantly contribute to burned areas and may show specific emission profiles. Our objective was to depict and quantify the primary-derived aerosols and precursors of secondary particulate species released during shrubland experimental fires, in which fire-line intensity values were equivalent to those of moderate shrubland wildfires, by using a number of different methodologies for the characterization of organic and inorganic compounds in both gas-phase and particulate-phase. Emissions of PM mass, particle number concentrations and organic and inorganic PM x components during flaming and smouldering phases were characterized in a field shrubland fire experiment. Our results revealed a clear prevalence of K+ and SO4 2− as inorganic ions released during the flaming–smouldering processes, accounting for 68–80% of the inorganic soluble fraction. During the residual-smouldering phases, in addition to K+ and SO4 2−, Ca2+ was found in significant amounts probably due the predominance of re-suspension processes (ashes and soil dust) over other emission sources during this stage. Concerning organic markers, the chromatograms were dominated by phenols, n-alkanals and n-alkanones, as well as by alcohol biomarkers in all the PM x fractions investigated. Levoglucosan was the most abundant degradation compound with maximum emission factors between 182 and 261 mg kg−1 in PM2.5 and PM10 respectively. However, levoglucosan was also observed in significant amounts in the gas-phase. The most representative organic volatile constituents in the smoke samples were alcohols, carbonyls, acids, monocyclic and bicyclic arenes, isoprenoids and alkanes compounds. The emission factors obtained in this study may contribute to the validation and improvement of national and international emission inventories of this intricate and diffuse emission source. [Copyright &y& Elsevier]

Abstract: This work was carried out in the framework of the Cal-Mex project, which focuses on investigating the atmosphere along Mexico–California border region. Sampling was carried out at two sites located in Tijuana urban area: Parque Morelos and Metales y Derivados. PM2.5 and PM10 24 h samples were collected every three days from 17th May 2010 to 27th June 2010, and were used for gravimetric and chemical analyses (major and minor elements, inorganic ions, organic and elemental carbon) of PM. A subsequent Positive Matrix Factorization (PMF) analysis was performed. PM2.5 and PM10 average concentrations during Cal-Mex were relatively lower compared to usual annual averages. Trace elements concentrations recorded in the present study were lower than those recorded in Mexico City in 2006, with the exception of Pb at Metales y Derivados, attributed to the influence of a specific industrial source, which also includes As, Cd and Tl. Apart from this industrial source, both urban sites were found to be affected by similar sources with respect to bulk PM. Fine PM (PM2.5) was mainly apportioned by fueloil and biomass combustion and secondary aerosols, and road traffic. Coarse PM (PM2.5–10) was mainly apportioned by a mineral source (sum of road dust resuspension, construction emissions and natural soil) and fresh and aged sea salt. The road traffic was responsible for more than 60% of the fine elemental carbon and almost 40% of the fine organic matter. [Copyright &y& Elsevier]

Abstract: Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well described in the air quality models, hampering a reliable description of air pollution and related health effects. In this study we experimentally show that the emission strength of resuspension varies widely among road dust components/sources. Our results offer the first experimental evidence of different emission rates for mineral dust, heavy metals and carbon fractions due to traffic-induced resuspension. Also, the same component (or source) recovers differently in a road in Barcelona (Spain) and a road in Utrecht (The Netherlands). This finding has important implications on atmospheric pollution modelling, mostly for mineral dust, heavy metals and carbon species. After rain events, recoveries were generally faster in Barcelona rather than in Utrecht. The largest difference was found for the mineral dust (Al, Si, Ca). Tyre wear particles (organic carbon and zinc) recovered faster than other road dust particles in both cities. The source apportionment of road dust mass provides useful information for air quality management. [Copyright &y& Elsevier]

Abstract: An atmospheric aerosol study was performed in 2008 inside an urban road tunnel, in Lisbon, Portugal. Using a high volume impactor, the aerosol was collected into four size fractions (PM0.5, PM0.5–1, PM1 – 2.5 and PM2.5 – 10) and analysed for particle mass (PM), organic and elemental carbon (OC and EC), polycyclic aromatic hydrocarbons (PAH), soluble inorganic ions and elemental composition. Three main groups of compounds were discriminated in the tunnel aerosol: carbonaceous, soil component and vehicle mechanical wear. Measurements indicate that Cu can be a good tracer for wear emissions of road traffic. Cu levels correlate strongly with Fe, Mn, Sn and Cr, showing a highly linear constant ratio in all size ranges, suggesting a unique origin through sizes. Ratios of Cu with other elements can be used to source apportion the trace elements present in urban atmospheres, mainly on what concerns coarse aerosol particles. [Copyright &y& Elsevier]

Abstract: Forest fire emissions modify the chemical composition of the atmosphere and the earth''s climate system. The Ayoraburning experiment was designed to assess and quantify fire emissions from Mediterranean shrublands. A number of gaseous pollutants and particulate matter metrics (CO2, CO, CH4, PM2.5) were measured during 3 burning replicates by using real-time monitors. Quantification of carbon emissions released during the experiments showed that 71% was CO2, 26% CO, 3% CH4, and only 0.3% was particulate carbon. Emission factors obtained for CO2, CO and CH4 were 1257 ± 40, 453 ± 28 and 46 ± 12 g kg−1 dry matter, respectively, and combustion efficiencies ranged from 0.46 to 0.99. The experiments allowed the estimation of carbon emission in the different fire phases. Thus, 25% of carbon was sampled in the flaming phase and 75% of C in the smoldering phase. Current natural greenhouse gas (GHG) emission inventories in Mediterranean countries underestimate the actual emissions from forest fires since they do not consider forest shrub understory and shrublands and since they assume that the CO2 emitted is offset by forest re-growth. Our results may be used to improve current forest-fire emission inventories in southern Europe with special emphasis on shrublands. [Copyright &y& Elsevier]

Abstract: Aim: The aims of this study were to investigate the relationship between pregnant women''s personal exposures to NO x , NO2, PM2.5 concentration and absorbance as a marker for black carbon and their indoor and outdoor concentration levels at their residence, and also to identify predictors of personal exposure and indoor levels using questionnaire and time activity data. Method: We recruited 54 pregnant women in Barcelona who carried a personal PM2.5 sampler for two days and NO x /NO2 passive badges for one week, while indoor and outdoor PM2.5 and NO x /NO2 levels at their residence were simultaneously measured. Time activity and house characteristics were recorded. Gravimetry determinations for PM2.5 concentration and absorbance measurements were carried out on the PM2.5 filter samples. Results: Levels of personal exposure to NO x , PM2.5 and absorbance were slightly higher than indoor and outdoor levels (geometric mean of personal NO x  = 61.9 vs indoor NO x  = 60.6 μg m−3), while for NO2 the indoor levels were slightly higher than the personal ones. Generally, there was a high statistically significant correlation between personal exposure and indoor levels (Spearman''s r between 0.78 and 0.84). Women spent more than 60% of their time indoors at home. Ventilation of the house by opening the windows, the time spent cooking and indicators for traffic intensity were re-occurring statistically significant determinants of the personal and indoor pollutants levels with models for NO x explaining the 55% and 60% of the variability respectively, and models for NO2 explaining the 39% and 16% of the variability respectively. Models for PM2.5 and absorbance explained the least of the variability. Conclusion: Our findings improve the current understanding of the characterization and inter-associations between personal, indoor and outdoor pollution levels among pregnant women. Variability in personal and indoor NO x and to a lesser extent NO2 levels could be explained well, but not the variability in PM2.5 could be explained. [Copyright &y& Elsevier]

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: In Winter 2009 an intensive experimental campaign (DAURE) was conducted in an urban site (Barcelona) and in an elevated rural background station (Montseny) in the western Mediterranean basin. During this period three main scenarios were identified based on distinct meteorological conditions: A) temperature inversion, B) cloudy days in normal conditions, and C) intense sea breeze. Filter samples of the submicron fraction (PM1) collected during these scenarios were analysed for organic tracer compounds to gain insight into the composition, sources, formation and processing of aerosol organic matter in the region under contrasting conditions. The results were compared to on-line Aerosol Mass Spectrometry (AMS) measurements. Scenario A conditions had the highest pollution concentrations in Barcelona (traffic and secondary aerosol formation) and lowest in Montseny whose sampling station remained above the mixing layer. Under scenario B the biomass burning contribution was highest in Montseny, reflecting nearby biomass burning sources. Under scenario C, the traffic-related contributions were highest in Montseny and lowest in Barcelona in comparison to the other samples, reflecting the enhanced pollution transport to Montseny and greater dilution in Barcelona. In this scenario, secondary organic aerosol was highest in Montseny. Molecular marker data and AMS source apportionment showed strong to moderate correlation for a) dicarboxylic acids and oxygenated organic aerosol, b) levoglucosan and biomass burning organic aerosol and c) Σn-alkanes and hydrocarbon-like organic aerosol. [Copyright &y& Elsevier]

Abstract: Atmospheric aerosol samples from a boreal forest (Hyytiälä, April 2007), a rural site in Hungary (K-puszta, summer 2008), a polluted rural area in Italy (San Pietro Capofiume, Po Valley, April 2008), a moderately polluted rural site in Germany located on a meadow (Melpitz, May 2008), a natural park in Spain (Montseny, March 2009) and two urban background locations (Zurich, December 2008, and Barcelona, February/March 2009) were collected. Aliphatics, polycyclic aromatic hydrocarbons, carbonyls, sterols, n-alkanols, acids, phenolic compounds and anhydrosugars in aerosols were chemically characterised by gas chromatography–mass spectrometry, along with source attribution based on the carbon preference index (CPI), the ratios between the unresolved and the chromatographically resolved aliphatics, the contribution of wax n-alkanes, n-alkanols and n-alkanoic acids from plants, diagnostic ratios of individual target compounds and source-specific markers to organic carbon ratios. In spite of transboundary pollution episodes, Hyytiälä registered the lowest levels among all locations. CPI values close to 1 for the aliphatic fraction of the Montseny aerosol suggest that the anthropogenic input may be associated with the transport of aged air masses from the surrounding industrial/urban areas, which superimpose the locally originated hydrocarbons with biogenic origin. Aliphatic and aromatic hydrocarbons in samples from San Pietro Capofiume reveal that fossil fuel combustion is a major source influencing the diel pattern of concentrations. This source contributed to 25–45% of the ambient organic carbon (OC) at the Po Valley site. Aerosols from the German meadow presented variable contributions from both biogenic and anthropogenic sources. The highest levels of vegetation wax components and biogenic secondary organic aerosol (SOA) products were observed at K-puszta, while anthropogenic SOA compounds predominated in Barcelona. The primary vehicular emissions in the Spanish city accounted for around 25–30% of the OC in aerosols. Besides the traffic input (10% of OC), residential wood burning was found to be another dominant emission source contributing to the atmospheric aerosol (up to 38% of OC) at the Swiss urban location. It was estimated that around 10% of the OC mass in the urban sites originates from cooking emissions. Aerosols from the urban area of Zurich presented a much higher PAH content, and benzo(a)pyrene equivalent concentrations sometimes exceeding the mandatory limit. [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]

Abstract: Several studies conducted in urban areas have pointed out that road dust resuspension contributes significantly to PM concentration levels. Street washing is one of the methods proposed to reduce resuspended road dust contributions to ambient PM concentrations. As resuspended particles are mainly found in the coarse mode, published studies investigating the effects of street washing have focused on PM10 size fraction. As the PM2.5 mass fraction of particles originating from mechanical abrasion processes may still be significant we conducted a study in order to evaluate the effects of street washing on the mitigation of resuspension of fine particles. The PM2.5 mass concentration data were examined and integrated with the occurrence of street washing activities. In addition, the effect of the meteorological variability, traffic flow and street washing activities, on ambient PM2.5 levels was evaluated by means of a multivariate regression model. The results revealed that traffic flow is the most important factor that controls PM2.5 hourly concentrations while street washing activities did not influence fine particle mass levels. [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]

Abstract: In summer 2009, emissions of trace gases and aerosols from several wildfires occurring in Portugal were sampled. A portable high-volume sampler was used to collect sequentially, on quartz fibre filters, coarse (PM2.5–10) and fine (PM2.5) smoke particles. Tedlar air sampling bags have been used for complementary chemical characterisation of the gaseous phase. The carbonaceous content (elemental and organic carbon, EC/OC) of particulate matter was analysed by a thermal-optical transmission technique. The levels of almost 50 elements were quantified by inductively coupled plasma-mass spectrometry. The water-soluble ions were obtained by ion chromatography. Emission factors of species that are favoured by the smouldering phase (e.g. CO) were above the values reported in the literature for biomass burning in other ecosystems. The CO emission factors were 231 ± 117 g kg−1 biomass (dry basis) burned. Emissions of compounds that are promoted in fresh plumes and during the flaming phase, such as CO2, were generally lower than those proposed for savannah and tropical forest fires. The CO2 emission factors ranged from about 1000 to 1700 g kg−1. Total hydrocarbons, PM2.5, PM10 and OC presented variable emissions, but in general substantially higher than values reported for wildfires in African and Amazonian biomes. The emission factors obtained in Portugal were as follows (in g kg−1 biomass, dry basis): 6–350 for total hydrocarbons, 0.5–42 for PM2.5, 1–60 for PM10, and 0.2–42 for OC (in PM10). The organic carbon-to-elemental carbon ratios measured in the present study largely exceeded those obtained by other researchers. The aerosol mass was dominated by organic matter (OC/PM2.5 = 50 ± 18%, OC/PM2.5–10 = 36 ± 18%). The metal elements represented, on average, 1.23 and 0.91%, while the measured water-soluble ions accounted for 2.6 and 2.1% of the PM2.5 and PM2.5–10 mass, respectively. Carbonates accounted for 0.15–3.1% (average = 0.83%) of PM2.5–10. The dominant elements were B, Ti, Mn, Cu, Zn, Zr and Ba. [Copyright &y& Elsevier]

Abstract: Mineral dust is an important aerosol species in the Earth’s atmosphere and has a major source within North Africa, of which the Sahara forms the major part. Aerosol Time of Flight Mass Spectrometry (ATOFMS) is first used to determine the mixing state of dust particles collected from the land surface in the Saharan region, showing low abundance of species such as nitrate and sulphate internally mixed with the dust mineral matrix. These data are then compared with the ATOFMS single particle mass spectra of Saharan dust particles detected in the marine atmosphere in the vicinity of the Cape Verde islands, which are further compared with those from particles with longer atmospheric residence sampled at a coastal station at Mace Head, Ireland. Saharan dust particles collected near the Cape Verde Islands showed increased internally mixed nitrate but no sulphate, whilst Saharan dust particles collected on the coast of Ireland showed a very high degree of internally mixed secondary species including nitrate, sulphate and methanesulphonate. This uptake of secondary species will change the pH and hygroscopic properties of the aerosol dust and thus can influence the budgets of other reactive gases, as well as influencing the radiative properties of the particles and the availability of metals for dissolution. [Copyright &y& Elsevier]

Abstract: Samples of particulate matter were collected during the period from October 2006 through September 2007 in a rural station located 12 km from the city of Colima. A total of 3600 particles were analyzed by SEM-EDS and then classified by their chemical composition and morphology in order of abundance: those rich in C, Fe, Si–Al, Cl–Na, Ca, Ba; and to a lesser abundance, particles rich in heavy metals such as Pb and V–Ni were observed. A factorial analysis was carried out to determine the main elements related with the emission sources such as crustal/farming; fuel-oil; marine; volcanic activity and industry. Trough the seasons, the dominant winds causes the presence of anthropogenic particles in the rural site. The information presented in this study aims to give insight and detailed of the analysis of the morphological characteristics and chemical composition of atmospheric particles at individual level in a rural site from Colima State, Mexico. [Copyright &y& Elsevier]

Abstract: For more than two decades a number of frameworks for scientific knowledge production are being proposed by science and technology researchers. They all advocate an extended involvement of non-specialists, in particular when it comes to knowledge production applicable to practical societal problems. We look to what extent these new frameworks have taken ground within a particular research community: the ACCENT Network of Excellence which coordinates European atmospheric chemistry and physics research applicable to air pollution and climate change. We did so by stimulating a debate through a “blog”, a survey and in-depth interviews with ACCENT scientists about the interaction between science, policy making and civil society, to which a great deal of ACCENT member contributed in writing or verbally. Most of them had interactions with policy makers and/or the general public, and they generally believe that interactions with spheres other than the scientific are needed. While such interactions give personal insight and satisfaction, they seem to have little impact on the goals and the practice of the scientific work itself. Extended frameworks of science production that go beyond the disciplinary mode seem to emerge at the level of individual scientists, yet they still need to find their way to the level of scientific project management. In this paper we discuss the justifications and barriers to implement a higher degree of extended knowledge integration in applied science projects such as ACCENT. It is felt that the community of atmospheric chemists and physicists is mature for such an implementation and recommendations are given to help and make this happen. [Copyright &y& Elsevier]

The physical characterisation of metrics representative of ambient air particle concentration is becoming a topic of great interest for urban air quality monitoring and human exposure assessment. In this article, the influence of sea breeze circulation and primary road traffic emissions on the relationship between the urban aerosol number (N3, particles >3nm), black carbon <10μm (BC), PM1, PM2.5, PM2.5–10 (PMx) concentrations was studied in a coastal city (Santa Cruz de Tenerife, Canary Islands). The daily cycles of sea and mountain breezes (inland during daylight and seaward at night) and road traffic emissions exerted a great, and well differentiated, influence on the BC, N3 and PMx concentrations. In this scenario, the following major aerosol features were observed: (1) fresh vehicle exhaust emissions resulted in high BC and N3 concentrations, in such a way that these two metrics increased when the “road traffic intensity (vehiclesh−1)/wind speed” ratio increased, (2) PM1 and PM2.5 levels were lower during daylight (due to inland entry of relatively clean marine air masses) than at night (due to the seaward drainage airflow resulting in the transport of aged particulate pollutants from the city), (3) although N3 and BC concentrations exhibited a significant correlation during the whole study period, the N3/BC ratio experienced a daily evolution with a maximum during daylight. Thus, high N3 concentrations associated with high N3/BC ratios and high solar irradiance conditions were recorded during the daylight inland breeze period due to an enhancement of processes favouring new particle formation. Data analysis points out that this enhancement in the new particle formation processes is strongly related to the nucleation of photo-oxidized vapours under the relatively low PMx (and consequently low aerosol surface area) concentrations prompted by the inland entry of clean marine air due to the daylight breeze blowing. The results obtained show that, in addition to the vehicle exhaust emissions, new particle formation in coastal urban areas due to photo-oxidation processes may significantly contribute to the ultrafine particle concentration. [Copyright &y& Elsevier]