[Show abstract][Hide abstract] ABSTRACT: The ceramic industry is an industrial sector in need of significant process changes, which may benefit from innovative technologies such as laser sintering of ceramic tiles. Such innovations result in a considerable research gap within exposure assessment studies for process-generated ultrafine and nanoparticles. This study addresses this issue aiming to characterise particle formation, release mechanisms and their impact on personal exposure during a tile sintering activity in an industrial-scale pilot plant, as a follow-up of a previous study in a laboratory-scale plant. In addition, possible particle transformations in the exhaust system, the potential for particle release to the outdoor environment, and the effectiveness of the filtration system were also assessed. For this purpose, a tiered measurement strategy was conducted.
Full-text · Article · Feb 2016 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: Due to the need to better characterise the ultrafine particles fraction and related personal exposure, several impactors have been developed to enable the collection of ultrafine particles (<100 nm). However, to the authors’ kno wledge there have been no field campaigns to-date intercomparing impactor collection of ultrafine particles. The purpose of this study was two-fold: 1) to assess the performance of a number of conventional and nano-range cascade impactors with regard to the particle mass size distribution under different environmental conditions and aerosol loads and types, and 2) to characterise aerosol size distributions including ultrafine particles using impactors in 2 European locations. The impactors used were: (i) Berner low-pressure impactor (BLPI; 26 nm - 13.5 μm), (ii) nano-Berner low-pressure impactor (nano-BLPI; 11 nm - 1.95 μm) and (iii) Nano-microorifice uniform deposit impactor (nano-Moudi; 10 nm-18 μm), and (iv) Personal cascade impactor Sioutas (PCIS; <250 nm - 10 μm). Taking the BLPI as an internal reference, the best agreement regarding mass size distributions was obtained with the nano-BLPI, independently of the aerosol load and aerosol chemical composition. The nano-Moudi showed a good agreement for part icle sizes >320 nm, whereas for particle diameters <320 nm this instrument recorded larger mass concentrations in outdoor air than the internal reference. This difference could be due to particle bounce, to the dissociation of semi volatiles in the coarser stages and/or to particle shrinkage during transport through the impactor due to higher temperature inside this impactor. Further research is needed to understand this behaviour. With regard to the PCIS, their size-resolved mass concentrations were compar able with other impactors for PM1, PM2 and PM10, but the cut-off at 250 nm did not seem to be consistent with that of the internal reference.
Full-text · Article · Jan 2016 · Atmospheric Chemistry and Physics
[Show abstract][Hide abstract] ABSTRACT: The performance of three portable monitors (micro-aethalometer AE51, DiscMini, Dusttrak DRX) was assessed for outdoor air exposure assessment in a representative Southern European urban environment. The parameters evaluated were black carbon, particle number concentration, alveolar lung-deposited surface area, mean particle diameter, PM10, PM2.5 and PM1. The performance was tested by comparison with widely used stationary instruments (MAAP, CPC, SMPS, NSAM, GRIMM aerosol spectrometer). Results evidenced a good agreement between most portable and stationary instruments, with R2 values mostly >0.80. Relative differences between portable and stationary instruments were mostly <20%, and <10% between different units of the same instrument. The only exception was found for the Dusttrak DRX measurements, for which occasional concentration jumps in the time series were detected. Our results validate the performance of the black carbon, particle number concentration, particle surface area and mean particle diameter monitors as indicative instruments (tier 2) for outdoor air exposure assessment studies.
Preview · Article · Oct 2015 · Atmospheric Environment
[Show abstract][Hide abstract] ABSTRACT: Thermal-optical analysis is currently under consideration by the European standardization body (CEN) as the reference method to quantitatively determine organic carbon (OC) and elemental carbon (EC) in ambient air. This paper presents an overview of the critical parameters related to the thermal-optical analysis including thermal protocols, critical factors and interferences of the methods examined, method inter-comparisons, inter-laboratory exercises, biases and artifacts, and reference materials. The most commonly used thermal protocols include NIOSH-like, IMPROVE_A and EUSAAR_2 protocols either with light transmittance or reflectance correction for charring. All thermal evolution protocols are comparable for total carbon (TC) concentrations but the results vary significantly concerning OC and especially EC concentrations. Thermal protocols with a rather low peak temperature in the inert mode like IMPROVE_A and EUSAAR_2 tend to classify more carbon as EC compared to NIOSH-like protocols, while charring correction based on transmittance usually leads to smaller EC values compared to reflectance. The difference between reflectance and transmittance correction tends to be larger than the difference between different thermal protocols. Nevertheless, thermal protocols seem to correlate better when reflectance is used as charring correction method. The difference between EC values as determined by the different protocols is not only dependent on the optical pyrolysis correction method, but also on the chemical properties of the samples due to different contributions from various sources. The overall conclusion from this literature review is that it is not possible to identify the "best" thermal-optical protocol based on literature data only, although differences attributed to the methods have been quantified when possible.
[Show abstract][Hide abstract] ABSTRACT: Epidemiological and toxicological studies have demonstrated the association between Black Carbon in indoor and outdoor air and the occurrence of health risks. Data on air quality in schools is of special interest, as children are more vulnerable to health hazards. In this context, indoor and outdoor measurements of real-time Equivalent Black Carbon (EBC) were collected at 39 primary schools located in Barcelona (Spain), with classrooms naturally ventilated under warm weather conditions. A main contribution of road traffic emissions to indoor and outdoor EBC levels was evidenced through different approaches. Simultaneous measurements of EBC levels at schools under different traffic conditions revealed concentrations by 30-35% higher at schools exposed to higher vehicles intensities. Moreover, a significant correlation was obtained between average outdoor EBC levels at different districts of the city and the percentage of surface area in each district used for the road network (R2 = 0.61). Higher indoor than outdoor levels were recorded at some instances when the indoor sampling location was relatively closer to road traffic, even under low outdoor temperatures. Indeed, the average indoor/outdoor EBC ratios for each school correlate moderately between campaigns in spite of significant differences in temperature between sampling periods. These two facts highlight the strong dependency of the EBC levels on the distance to traffic. The peaks of exposure inside the classrooms seemed to be determined by outdoor concentrations, as shown by the parallelism between indoor and outdoor mean EBC daily cycles and the similar contribution of traffic rush hours to indoor and outdoor daily mean levels. The airtightness of the classroom was suggested as the responsible for the indoor/outdoor ratios of EBC higher than 1 recorded at nights.
[Show abstract][Hide abstract] ABSTRACT: The use of laser technology in the ceramic industry is undergoing an increasing trend, as it improves surface properties. The present work aimed to assess ultrafine and nanoparticle emissions from two different types of laser treatments (tile sintering and ablation) applied to two types of tiles. New particle formation mechanisms were identified, as well as primary nanoparticle emissions, with concentrations reaching up to 6.7×106 particles cm−3 and a mean diameter of 18 nm. Nanoparticle emission patterns were strongly dependent on temperature and raw tile chemical composition. Nucleation events were detected during the thermal treatment independently of the laser application. TEM images evidenced spherical ultrafine particles, originating from the tile melting processes. When transported across the indoor environment, particles increased in size (up to 38 nm) with concentrations remaining high (2.3×106 particles cm−3). Concentrations of metals such as Zn, Pb, Cu, Cr, As and TI were found in particles <250 nm.
Full-text · Article · Jun 2015 · Journal of Aerosol Science
[Show abstract][Hide abstract] ABSTRACT: Infiltration of outdoor-sourced particles into indoor environments in 39 schools in Barcelona was assessed during school hours. Tracers of road traffic emissions (NO2, Equivalent Black Carbon (EBC), Ultrafine Particles (UFP), Sb), secondary inorganic aerosols (SO42−, NO3−, NH4+) and a number of PM2.5 trace elements showed median indoor/outdoor (I/O) ratios ≤ 1, indicating that outdoor sources importantly contributed to indoor concentrations. Conversely, OC and mineral components had I/O ratios>1. Different infiltration factors were found for traffic and secondary components (0.31–0.75 and 0.50–0.92, cold and warm season respectively), with maxima corresponding to EBC and Cd. Higher concentrations of indoor-generated particles were observed when closed windows hindered dispersion (cold season). Building age was not a major determinant of indoor levels. Neither were the window's material, except for NO2 (with an increase of 8 μg m−3 for wood framed windows) and the mineral components (also dependent on the presence of sand in a distance <20 m) that reach the indoor environment via soil adhering to footwear with their dispersion being more barred by Aluminium/PVC framed windows than the wooden ones. Enlarged indoor concentrations of some trace elements suggest the presence of indoor sources that should be further investigated in order to achieve a healthier school indoor environment.
No preview · Article · Apr 2015 · Atmospheric Environment
[Show abstract][Hide abstract] ABSTRACT: At city level, personal monitoring is the best way to assess people's exposure. However, it is usually estimated from a few monitoring stations. Our aim was to determine the exposure to black carbon (BC) and BC dose for 45 schoolchildren with portable microaethalometers and to evaluate the relationship between personal monitoring and fixed stations at schools (indoor and outdoor) and from an urban background (UB) site. Personal BC concentrations were 20% higher than in fixed stations at schools. Linear Mixed-Effect Models showed low R(2) between personal measurements and fixed stations at schools (R(2) ≤0.28), increasing to R(2) ≥0.70 if considering only periods when children were at schools. For the UB station the respective R(2) were 0.18 and 0.45, indicating the importance of the distance to the monitoring station when assessing exposure. During the warm season, the fixed stations agreed better with personal measurements than during the cold one. Children spent 6% of their time on commuting but received 20% of their daily BC dose, due to co-occurrence with road traffic rush hours and the close proximity to the source. Children received 37% of their daily-integrated BC dose at school. Indoor environments (classroom and home) were responsible for the 56% BC dose. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: In urban areas, primary and secondary organic aerosols are typically considered to originate from vehicular traffic emissions. However, industrial emissions within or in the vicinity of urban areas may also be significant contributors to carbonaceous aerosol concentrations. This hypothesis was tested and validated in two urban areas in Spain. The observed unusual dominance of organic carbon (OC) over elemental carbon (EC), the analysis of the variability of OC, EC and OC/EC and their correlation with transport patterns suggested the presence of OC sources associated with industrial activities. A methodology based on chemical speciation of particulate matter (PM) followed by the application of receptor modelling techniques allowed for the identification of the specific industrial sources of OC, which were linked to primary OC emissions from a grain drying plant (cereal) and to secondary OC formation from paper production activities (paper mills), as well as from urban sources and biogenic emissions. This work presents an integrated approach to identifying and characterizing of industrial sources of carbonaceous aerosols in urban areas, aiming to improve the scarce body of literature currently available on this topic.
No preview · Article · Feb 2015 · Environmental Science and Pollution Research
[Show abstract][Hide abstract] ABSTRACT: A comparison exercise on thermal-optical elemental carbon/organic carbon (ECOC) analysers was carried out among 17 European laboratories. Contrary to previous comparison exercises, the 17 participants made use of an identical instrument set-up, after correcting for temperature offsets with the application of a recently developed temperature calibration kit (Sunset Laboratory Inc, OR, US). Temperature offsets reported by participants ranged from −93 to +100 °C per temperature step. Five filter samples and two sucrose solutions were analysed with both the EUSAAR2 and NIOSH870 thermal protocols.
z scores were calculated for total carbon (TC); nine outliers and three stragglers were identified. Three outliers and eight stragglers were found for EC. Overall, the participants provided results between the warning levels with the exception of two laboratories that showed poor performance, the causes of which were identified and corrected through the course of the comparison exercise. The TC repeatability and reproducibility (expressed as relative standard deviations) were 11 and 15% for EUSAAR2 and 9.2 and 12% for NIOSH870; the standard deviations for EC were 15 and 20% for EUSAAR2 and 20 and 26% for NIOSH870.
TC was in good agreement between the two protocols, TCNIOSH870 = 0.98 × TCEUSAAR2 (R2 = 1.00, robust means). Transmittance (TOT) calculated EC for NIOSH870 was found to be 20% lower than for EUSAAR2, ECNIOSH870 = 0.80 × ECEUSAAR2 (R2 = 0.96, robust means). The thermograms and laser signal values were compared and similar peak patterns were observed per sample and protocol for most participants. Notable deviations from the typical patterns indicated either the absence or inaccurate application of the temperature calibration procedure and/or pre-oxidation during the inert phase of the analysis. Low or zero pyrolytic organic carbon (POC), as reported by a few participants, is suggested as an indicator of an instrument-specific pre-oxidation. A sample-specific pre-oxidation effect was observed for filter G, for all participants and both thermal protocols, indicating the presence of oxygen donors on the suspended particulate matter. POC (TOT) levels were lower for NIOSH870 than for EUSAAR2, which is related to the heating profile differences of the two thermal protocols.
Full-text · Article · Feb 2015 · Atmospheric Measurement Techniques
[Show abstract][Hide abstract] ABSTRACT: Indoor and outdoor measurements of real-time ultrafine particles (UFP; N10-700 in this study) number concentration and average diameter were collected twice at 39 primary schools located in Barcelona (Spain), with classrooms naturally ventilated under warm weather conditions. Simultaneous outdoor N concentration measurements at schools under different traffic exposures showed the important role of this source, with higher levels by 40% on average at schools near heavy traffic, highlighting thus the increased exposure of children due to urban planning decisions. A well-defined spatial pattern of outdoor UFP levels was observed. Midday increases in outdoor N levels mainly attributed to nucleation processes have been recorded both at high and low temperatures in several of the outdoor school sites (increasing levels by 15%-70%). The variation of these increases also followed a characteristic spatial pattern, pointing at schools' location as a key variable in terms of UFP load owing to the important contribution of traffic emissions. Indoor N concentrations were to some extent explained by outdoor N concentrations during school hours, together with average temperatures, related with natural ventilation. Outdoor midday increases were generally mimicked by indoor N concentrations, especially under warm temperatures. At specific cases, indoor concentrations during midday were 30%-40% higher than outdoor. The time scale of these observations evidenced the possible role of: a) secondary particle formation enhanced by indoor precursors or conditions, maybe related with surface chemistry reactions mediated by O3, and/or b) UFP from cooking activities. Significant indoor N increases were detected after school hours, probably associated with cleaning activities, resulting in indoor N concentrations up to 3 times higher than those in outdoor. A wide variability of indoor/outdoor ratios of N concentrations and mean UFP sizes was detected among schools and measurement periods, which seems to be partly associated with climatic conditions and O3 levels, although further research is required.
No preview · Article · Jul 2014 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: Particle size distribution patterns of trace elements and metals across three size fractions (<0.25 μm, quasi-ultrafine particles, q-UF; 0.25–2.5 μm, accumulation particles; 2.5–10 μm, coarse particles) were analysed in indoor and outdoor air at 39 primary schools across Barcelona (Spain). Special attention was paid to emission sources in each particle size range. Results evidenced the presence in q-UF particles of high proportions of elements typically found in coarse PM (Ca, Al, Fe, Mn or Na), as well as several potentially health-hazardous metals (Mn, Cu, Sn, V, Pb). Modal shifts (e.g., from accumulation to coarse or q-UF particles) were detected when particles infiltrated indoors, mainly for secondary inorganic aerosols. Our results indicate that the location of schools in heavily trafficked areas increases the abundance of q-UF particles, which infiltrate indoors quite effectively, and thus may impact children exposure to these health-hazardous particles.
[Show abstract][Hide abstract] ABSTRACT: This study aims at interpreting the 2001-2012 trends of major air pollutants in Spain, with a major focus on evaluating their relationship with those of the national emission inventories (NEI) and policy actions. Marked downward concentration trends were evidenced for PM10, PM2.5 and CO. Concentrations of NO2 and NOx also declined but in a lesser proportion at rural and traffic sites. At rural sites O3 has been kept constant, whereas it clearly increased at urban and industrial sites. Comparison of the air quality trends and major inflection points with those from NEIs, the National Energy Consumption and the calendar of the implementation of major policy actions allowed us to clearly identify major benefits of European directives on power generation and industrial sources (such as the Large Combustion Plants and the Integrated Pollution Prevention and Control Directives). This, together with a sharp 2007-2008 decrease of coal consumption has probably caused the marked parallel decline of SO2, NOx and for PM2.5 concentrations. Also the effect of the EURO 4 and 5 vehicle emission standards on decreasing emissions of PM and CO from vehicles is noticeable. The smooth decline in NO2-NOx levels is mostly attributed to the low efficiency of EURO 4 and 5 standards in reducing real life urban driving NO2 emissions. The low NOx decrease together with the complexity of the reactions of O3 formation is responsible for the constant O3 concentrations, or even the urban increase. The financial crisis has also contributed to the decrease of the ambient concentration of pollutants; however this caused a major reduction of the primary energy consumption from 2008 to 2009, and not from 2007 to 2008 when ambient air PM and SO2 sharply decreased. The meteorological influence was characterized by a 2008-2012 period favorable to the dispersion of pollutants when compared to the 2001-2007.
No preview · Article · Jun 2014 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: Children spend a third of their day in the classroom, where air pollution levels may differ substantially from those outdoors due to specific indoor sources. Air pollution exposure assessments based on atmospheric particle mass measured outdoors may therefore have little to do with the daily PM dose received by school children. This study aims to investigate outdoor and indoor sources of PM2.5 measured at 39 primary schools in Barcelona during 2012. On average 47% of indoor PM2.5 measured concentrations was found to be generated indoors due to continuous resuspension of soil particles (13%) and a mixed source (34%) comprising organic (skin flakes, clothes fibers, possible condensation of VOCs) and Ca-rich particles (from chalk and building deterioration). Emissions from seven outdoor sources penetrated easily indoors being responsible for the remaining 53% of measured PM2.5 indoors. Unpaved playgrounds were found to increase mineral contributions in classrooms by 5-6μg/m(3) on average with respect to schools with paved playgrounds. Weekday traffic contributions varied considerably across Barcelona within ranges of 1-14μg/m(3) outdoor and 1-10μg/m(3) indoor. Indoors, traffic contributions were significantly higher (more than twofold) for classrooms with windows oriented directly to the street, rather than to the interior of the block or to playgrounds. This highlights the importance of urban planning in order to reduce children's exposure to traffic emissions.
No preview · Article · Jun 2014 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: Proximity to road traffic involves higher health risks because of atmospheric pollutants. In addition to outdoor air, indoor air quality contributes to overall exposure. In the framework of the BREATHE study, indoor and outdoor air pollution was assessed in 39 schools in Barcelona. The study quantifies indoor and outdoor air quality during school hours of the BREATHE schools. High levels of fine particles (PM2.5), nitrogen dioxide (NO2), equivalent black carbon (EBC), ultrafine particle (UFP) number concentration and road traffic related trace metals were detected in school playgrounds and indoor environments. PM2.5 almost doubled (factor of 1.7) the usual urban background (UB) levels reported for Barcelona owing to high school-sourced PM2.5 contributions:  an indoor-generated source characterised mainly by organic carbon (OC) from organic textile fibres, cooking and other organic emissions, and by calcium and strontium (chalk dust) and;  mineral elements from sand-filled playgrounds, detected both indoors and outdoors. The levels of mineral elements are unusually high in PM2.5 because of the breakdown of mineral particles during playground activities. Moreover, anthropogenic PM components (such as OC and arsenic) are dry/wet deposited in this mineral matter. Therefore, PM2.5 cannot be considered a good tracer of traffic emissions in schools despite being influenced by them. On the other hand, outdoor NO2, EBC, UFP, and antimony appear to be good indicators of traffic emissions. The concentrations of NO2 are 1.2 times higher at schools than UB, suggesting the proximity of some schools to road traffic. Indoor levels of these traffic-sourced pollutants are very similar to those detected outdoors, indicating easy penetration of atmospheric pollutants. Spatial variation shows higher levels of EBC, NO2, UFP and, partially, PM2.5 in schools in the centre than in the outskirts of Barcelona, highlighting the influence of traffic emissions. Mean child exposure to pollutants in schools in Barcelona attains intermediate levels between UB and traffic stations.
Full-text · Article · May 2014 · Environment International
[Show abstract][Hide abstract] ABSTRACT: The mass concentration, chemical composition and sources of quasi-ultrafine (quasi-UFP, PM0.25), accumulation (PM0.25-2.5) and coarse mode (PM2.5-10) particles were determined in indoor and outdoor air at 39 schools in Barcelona (Spain). Quasi-UFP mass concentrations measured (25.6 mu g m(-3) outdoors, 23.4 mu g m(-3) indoors) are significantly higher than those reported in other studies, and characterised by higher carbonaceous and mineral matter contents and a lower proportion of secondary inorganic ions. Results suggest that quasi-UFPs in Barcelona are affected by local sources in the schools, mainly human activity (e. g. organic material from textiles, etc., contributing 23-46% to total quasi-UFP mass) and playgrounds (in the form of mineral matter, contributing about 9% to the quasi-UFP mass). The particle size distribution patterns of toxicologically relevant metals and major aerosol components was characterised, displaying two modes for most elements and components, and one mode for inorganic salts (ammonium nitrate and sulfate) and elemental carbon (EC). Regarding metals, Ni and Cr were partitioned mainly in quasi-UFPs and could thus be of interest for epidemiological studies, given their high redox properties. Exposure of children to quasi-UFP mass and chemical species was assessed by comparing the concentrations measured at urban background and traffic areas schools. Finally, three main indoor sources across all size fractions were identified by assessing indoor/outdoor ratios (I/O) of PM species used as their tracers: human activity (organic material), cleaning products, paints and plastics (Cl(-)source), and a metallic mixed source (comprising combinations of Cu, Zn, Co, Cd, Pb, As, V and Cr). Our results support the need to enforce targeted legislation to determine a minimum "safe" distance between major roads and newly built schools to reduce exposure to traffic-derived metals in quasi-UFPs.
No preview · Article · May 2014 · Atmospheric Chemistry and Physics