Indoor dust can contribute substantially to human exposure to known and contaminants of emerging concern (CECs). Novel compounds with high structural variability and different homologues are frequently discovered through screening of the indoor environment, implying that constant monitoring is required. The present study aimed at the identification and semi-quantification of CECs in 46 indoor dust samples collected in Belgium by liquid chromatography high-resolution mass spectrometry. Samples were analyzed applying a targeted and suspect screening approach; the latter based on a suspect list containing >4000 CECs. This allowed the detection of a total of 55 CECs, 34 and 21 of which were identified with confidence level (CL) 1/2 or CL 3, respectively. Besides numerous known contaminants such as di(2-ethylhexyl) phthalate (DEHP), di(2-ethylhexyl) adipate (DEHA) or tris(2-butoxyethyl) phosphate (TBOEP) which were reported with detection frequencies (DFs) > 90%, several novel CECs were annotated. These included phthalates with differing side chains, such as decyl nonyl and decyl undecyl phthalate detected with DFs >80% and identified through the observation of characteristic neutral losses. Additionally, two novel organophosphate flame retardants not previously described in indoor dust, i.e. didecyl butoxyethoxyethyl phosphate (DDeBEEP) and bis(butoxyethyl) butyl phosphate (BBEBP), were identified. The implementation of a dedicated workflow provided semi-quantitative concentrations for a set of suspects. Such data obtained for novel phthalates were in the same order of magnitude as the concentrations observed for legacy phthalates indicating their high relevance for human exposure. From the semi-quantitative data, estimated daily intakes and resulting hazard quotients (HQs) were calculated to estimate the exposure and potential health effects. Neither of the obtained HQ values exceeded the risk threshold, indicating no expected adverse health effects.

Mobile platforms are increasingly used to acquire air quality data at a high spatial and temporal resolution in complex urban environments. As such, mobile measurements provide a solution for short-term studies to acquire a spatially spread data set that would not be feasible if using stationary measurements. Mobile monitoring campaigns were carried out with a bicycle platform at two different urban locations, consisting of 20 and 24 repeated runs along a fixed route over a three-week period. The measurement runs were carried out on different days and at different times of the day, without systematical temporal coverage. Significant differences in UFP concentration were found within the day and between days, and also between several streets along the measurement route. These differences were related to traffic intensity and street characteristics. In contrast, PM10 concentrations differed between measurement days, but the within-day variability of PM10 was mostly non-significant. Additionally, the spatial variability was limited and the PM10 concentrations were only significantly different between busy streets, with high concentrations, and quiet background streets, with low ones. The results indicate that for most streets the number of runs was sufficient to give a good approximation of median daytime UFP concentration levels for the measurement period, and for some streets this number could even be reduced to less than 10. However, for PM10 a higher number of runs is needed, and this may be attributed to the significant background contribution to the roadside PM10 concentration, and the high variability of this. We conclude that a limited set of mobile measurements makes it possible to map locations with systematically higher or lower UFP and PM10 concentrations in urban environments.

By means of numerical simulations the aims of this study are as follows: (1) to investigate the dispersion and mixing of ultrafine particles (UFP) with pre-existing size resolved UFP in a street canyon and its vicinity with the ENVI-met 3D microscale model; (2) to show the effects of boundary conditions, like wind direction and traffic emissions, on the UFP concentration in the near vicinity; and (3) to evaluate the importance of deposition and coagulation at the street scale. The decrease in UFP concentration in nucleation mode particles (diameter < 30 nm) and Aitken mode particles (diameter between 30–100 nm) downwind of the street canyon is caused by the large differences in the size distributions of the emissions and the background. Based on the wind direction and traffic emissions, the UFP concentration over the rooftop increases by 23

Quaternary ammonium compounds (QACs) are a class of surfactants commonly used in disinfecting and cleaning products. Their use has substantially increased during the COVID-19 pandemic leading to increasing human exposure. QACs have been associated with hypersensitivity reactions and an increased risk of asthma. This study introduces the first identification, characterization and semi-quantification of QACs in European indoor dust using ion-mobility high-resolution mass spectrometry (IM-HRMS), including the acquisition of collision cross section values (DTCCSN2) for targeted and suspect QACs. A total of 46 indoor dust samples collected in Belgium were analyzed using target and suspect screening. Targeted QACs (n = 21) were detected with detection frequencies ranging between 4.2 and 100 %, while 15 QACs showed detection frequencies > 90 %. Semi-quantified concentrations of individual QACs showed a maximum of 32.23 µg/g with a median ∑QAC concentration of 13.05 µg/g and allowed the calculation of Estimated Daily Intakes for adults and toddlers. Most abundant QACs matched the patterns reported in indoor dust collected in the United States. Suspect screening allowed the identification of 17 additional QACs. A dialkyl dimethyl ammonium compound with mixed chain lengths (C16:C18) was characterized as a major QAC homologue with a maximum semi-quantified concentration of 24.90 µg/g. The high detection frequencies and structural variabilities observed call for more European studies on potential human exposure to these compounds. For all targeted QACs, drift tube IM-HRMS derived collision cross section values (DTCCSN2) are reported. Reference DTCCSN2 values allowed the characterization of CCS-m/z trendlines for each of the targeted QAC classes. Experimental CCS-m/z ratios of suspect QACs were compared with the CCS-m/z trendlines. The alignment between the two datasets served as an additional confirmation of the assigned suspect QACs. The use of the 4bit multiplexing acquisition mode with consecutive high-resolution demultiplexing confirmed the presence of isomers for two of the suspect QACs.

Steps: Literature search for data on emissions, distribution and concentration distribution of ultrafine particles in the vicinity of airports; Literature search for knowledge in the field of potentially harmful effects of ultrafine particles in the air around airports in relation to effects on health of residents in that area; Exploratory measurements of ultrafine particles in the vicinity of Schiphol; Generalization of the results to an annual average concentration distribution of ultrafine particles for the area around Schiphol using model calculations.

Undoubtedly, the most important advance in the environmental regulatory monitoring of elements of the last decade is the widespread introduction of ICP-mass spectrometry (ICP-MS) due to standards developed by the European Committee for Standardization. The versatility of ICP-MS units as a tool for the determination of major, minor and trace elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Se, Sn, Ti, V and Zn) in surface water, groundwater, river sediment, topsoil, subsoil, fine particulates and atmospheric deposition is illustrated in this paper. Ranges of background concentrations for major, minor and trace elements obtained from a regional case study (Flanders, Belgium) are summarized for all of these environmental compartments and discussed in the context of a harmonized implementation of European regulatory monitoring requirements. The results were derived from monitoring programs in support of EU environmental quality directives and were based on a selection of (non-polluted) background locations. Because of the availability of ICP-MS instruments nowadays, it can be argued that the main hindrance for meeting the European environmental monitoring requirements is no longer the technical feasibility of analysis at these concentration levels, but rather (i) potential contamination during sampling and analysis, (ii) too limited implementation of quality control programs, validating the routinely applied methods (including sampling and low level verification) and (iii) lack of harmonization in reporting of the chemical environmental status between the individual member states.

Background and aims: In the HEAPS (Health Effects of Air Pollution in Antwerp Schools) study the importance of traffic-related air pollution on the school and home location on children's health was assessed. 130 children (aged 6 to 12) from two schools participated in a biomonitoring study measuring oxidative stress, inflammation and cardiovascular markers.Methods: Personal exposure of schoolchildren to black carbon (BC) and nitrogen dioxide (NO2) was assessed using both measured and modeled concentrations. Air quality measurements were done in two seasons at approximately 50 locations, including the schools. The land use regression technique was applied to model concentrations at the children's home address and at the schools.Results: In this paper the results of the exposure analysis are given. Concentrations measured at school 2 h before the medical examination were used for assessing health effects of short term exposure. Over two seasons, this short term BC exposure ranged from 514 ng/m(3) to 6285 ng/m(3), and for NO2 from 11 mu g/m(3) to 36 mu g/m(3). An integrated exposure was determined until 10 days before the child's examination, taking into account exposures at home and at school and the time spent in each of these microenvironments. Land use regression estimates were therefore recalculated into daily concentrations by using the temporal trend observed at a fixed monitor of the official air quality network. Concentrations at the children's homes were modeled to estimate long term exposure (from 1457 ng/m3 to 3874 ng/m(3) for BC; and from 19 mu g/m(3) to 51 mu g/m(3) for NO2).Conclusions: The land use regression technique proved to be a fast and accurate means for estimating long term and daily BC and NO2 exposure for children living in the Antwerp area. The spatial and temporal resolution was tailored to the needs of the epidemiologists involved in this study. (C) 2014 Elsevier B.V. All rights reserved.

1 VITO Flemish Institute for Technological Research, Belgium 2 VMM Flemish Environment Agency, Department Air, Environment and Communication, Belgium 3 Public Health Service of Amsterdam, Department of Air Quality, the Netherlands 4 ECN Energy Research Centre of the Netherlands, Environment & Energy Engineering, the Netherlands 5 University of Leicester, Department of Chemistry, United Kingdom 6 Institut Scientifique de Service Public (ISSeP), Air Quality, Belgium

• A major part of the North West European (NWE) region is considered as a major hot spot zone for particulate matter. • Research shows that pollutant metrics not often measured in air quality monitoring networks such as the number and characteristics of airborne ultrafine particles (UFP) constitute better links to human health effects than e.g. NO2 and PM10. • However, there is little understanding of the spatial distribution of these metrics and their relationship with health aspects. This hampers decision makers from taking effective measures.

Simultaneous measurements of ultrafine particles (UFPs) were carried out at four sampling locations situated within a 1km2 grid area in a Belgian city, Borgerhout (Antwerp). All sampling sites had different orientation and height of buildings and dissimilar levels of anthropogenic activities (mainly traffic volume). The aims were to investigate: (i) the spatio-temporal variation of UFP within the area, (ii) the effect of wind direction with respect to the volume of traffic on UFP levels, and (iii) the spatial representativeness of the official monitoring station situated in the study area. All sampling sites followed similar diurnal patterns of UFP variation, but effects of local traffic emissions were evident. Wind direction also had a profound influence on UFP concentrations at certain sites. The results indicated a clear influence of local weather conditions and the more dominant effect of traffic volumes. Our analysis indicated that the regional air quality monitoring station represented the other sampling sites in the study area reasonably well; temporal patterns were found to be comparable though the absolute average concentrations showed differences of up to 35%.

Atmospheric aerosols were collected during the winter in Bethlehem, South Africa. The particulate mass concentrations, ambient carbon mass concentrations, and chemical composition of various particulate fractions showed that the area is highly polluted. The fine particle mass concentrations peaked at 1000 mu g/m(3) for PM2.5. Ambient carbon mass concentrations ranged from 20 to 40 mu g/m(3). Single particle analysis confirmed that the fine particle fraction was dominated by organic particles. The topographical conditions, causing a low inversion, together with the high amounts of emissions from biomass burning, result in unacceptable levels of air pollution and pose a considerable health threat to the population.

The aim of this study is to investigate the dispersion of ultrafine particles and its spatial distribution in a street canyon and its neighbourhood with the 3D CFD model ENVI-met®. The performance of the model at street scale is evaluated and the importance of the boundary conditions like wind field and traffic emissions on the UFP concentration is demonstrated. To support and validate the modelled results, a short-term measurement campaign was conducted in a street canyon in Antwerp, Belgium. The UFP concentration was measured simultaneously with P-TRACK (TSI Model 8525) at four different locations in the canyon. The modelled UFP concentrations compare well with the measured data (correlation coefficient R from 0.44 to 0.93) within the standard deviation of the measurements. Despite the moderate traffic flow in the street canyon, UFP concentrations in the canyon are in general double of the background concentrations, indicating the high local contribution for this particle number concentration. Some of the observed concentration profiles are not resembled by the model simulations. For these specific anomalies, further analysis is performed and plausible explanations are put forward. The role of wind direction and traffic emissions is investigated. The performance evaluation of ENVI-met® shows that in general the model qualitatively and quantitatively describes the dispersion of UFP in the street canyon study.

Background and Aims: Ultrafine particle (UFP) numbers show large short-term and small scale variation, making strategies to assess personal exposure to UFP in urban environment potentially very costly. Better insight in the role of local and regional processes, can give rise to methods to estimate UFP using correlated pollutants and regional indicators (Can et al 2011). Methods: UFP and NOx were measured simultaneously in Antwerp (Belgium) at three locations in a single street in Summer 2009, and in four different streets in a 1 km grid in Winter 2010. Different size fractions were compared to traffic counts and meteorological data. Regional contributions to various size fractions were assessed using night time number concentrations and air mass back-trajectory techniques. Results: In-street spatial variability of total particle number was rather low. UFP concentrations in four different streets showed a remarkably similar temporal trend on top of which the local component is added. Total particle number correlated poorly with traffic intensity. Mainly the 20 – 50 nm fractions are correlated with traffic intensity. The morning traffic peak leads to a distinct peak in total particle number, but this is not the case for the afternoon rush hour. Analysis of diurnal UFP concentrations for different size bins shows that both processes of agglomeration and condensation and meteorological conditions explain this decoupling of traffic and total particle number. Elevated total night-time UFP was mainly related to larger size fractions (50 - 100 nm). Higher concentrations of the larger size bins were associated with slow moving air masses. Conclusions: Although short-term variation in UFP number counts at urban traffic locations largely depends on local sources, similar temporal trends result both from regional processes and similar underlying traffic patterns. This study illustrates the potential to extrapolate measured UFP concentrations to similar locations using correlated pollutants and regional indicators.

The accuracy of the determination of Cr(VI) in ambient particulate matter remains a challenge from the point of view of minimal Cr species interconversion. Knowledge of this method induced oxidation and reduction is particularly relevant for the determination of Cr(VI) in ambient particulate matter, as the level of observed Cr(III) oxidation (average of 1.7% in this study) can contribute significantly to the monitored range of measured Cr(VI) in PM10. For Cr concentrations in PM10 > 10 ng Cr m(-3), this method induced oxidation could lead to false positive exceeding of an air quality guideline value of 0.2 ng Cr(VI) m(-3) in PM10. The median daily Cr(VI) concentration in PM10 measured over a monitoring period of more than 2 months at two locations close to a stainless steel factory amounted to 0.9 ng Cr(VI) m(-3) and 0.27 ng Cr(VI) m(-3). Average daily Cr(VI)/Cr ratios in PM10 of 3.5% and 2.6% were measured at these locations. The described monitoring for the determination of Cr(VI) in ambient air via alkaline impregnated filters is sensitive (method detection limit of 0.015 ng Cr(VI) m(-3)) and reproducible (precision of the method similar to 25%). The average Cr(VI) recovery of 75% strongly indicates the effects of ambient sampling conditions and ambient particles on the Cr(VI) recoveries. The stability of the Cr(VI) and the Cr(III) spike on 0.12 M NaHCO3 impregnated filters observed with XANES, indicates that the alkaline extraction of the filter in combination with the sampled air matrix is likely to induce the Cr conversions. The XANES spectra shows further that a Cr-spinel is the predominant component of Cr in ambient air PM10 at the monitored locations. (C) 2011 Elsevier Ltd. All rights reserved.

Nickel speciation and fractionation using a multidisciplinary approach are discussed for different particulate matter samples collected in industrial and rural atmospheres. The technologies utilized in this research span from X-ray Absorption Near Edge Structure (XANES) and X-Ray Diffraction (XRD) to a wet chemistry sequential leaching assay (including determination by inductively coupled plasma atomic emission spectroscopy, ICP-AES). The Zatka sequential leaching method provides an inexpensive assay to differentiate among 'soluble', 'sulfidic', 'metallic', and 'oxidic' chemical forms of Ni. The XANES technique is especially well suited for Ni speciation between and to a lesser extent within the 4 defined Ni species groups of the Zatka sequential leaching procedure. Limitations for interpretation in the present study with respect to XANES are the availability of pure phase Ni species for uptake as reference spectra and the collinearity between the spectra of Ni compounds within a Ni species group (e. g. NiSO4 center dot 6H(2)O and Ni(NO3)(2)center dot 6H(2)O). The Ni speciation and fractionation results on the particulate matter samples reflect in general a good agreement between the modified Zatka sequential leaching procedure and the XANES data. For the particulate matter collected in and close to a stainless steel factory, Ni included in a spinel structure (NiFe2O4) was identified as the principal Ni species. The particulate matter collected in rural atmosphere showed a 50/50 distribution between soluble and oxidic Ni species.

Methodology: The ultrafine particles (UFP) are modelled with the three dimensional computational fluid dynamics (3D CFD) model ENVI-met. The model was extended to account for different transformation processes that could have impact on the size and the number of particles (for example coagulation, deposition, etc).The UFP total number emissions are accounted based on the PARTICULATES project results. In order to validate the results,a measurement campaign was held in a street canyon in Antwerp, Belgium. The study domain contains a small street canyon in combination with a heavily trafficked boulevard perpendicular to it. The concentration of UFP in the street was measured at four different locations (one close to the busy boulevard, two opposite to each other in the middle and one at the other end). Results: Two examples are show the complexity and concerns when modeling the UFP dispersion and analyzing the results. The modelled concentration for total number of UFP was compared with measured UFP concentration at four locations in the street. The modelled trend in the UFP concentration well resembles the measured and it is within the uncertainties of the measurements showing an overall a good agreement. The wind direction is found to be of crucial importance for the dispersion of UFP. Besides there is a need of representative meteorological input suitable for modelling the UFP. Emissions are another parameter that alter the concentration of UFP and need to be addressed adequately. In the analysis averaging over long periods (hours) can mask important details and might lead to wrong conclusions. This model simulation and the comparison results can be used to better understand the dispersion of total number UFP concentrations in urban environment.

A new parameterization for size resolved ultrafine particles (UFP) traffic emissions is proposed based on the results of PARTICULATES project (Samaras et al., 2005). It includes the emission factors from the Emission Inventory Guidebook (2006) (total number of particles, #/km/veh), the shape of the corresponding particle size distribution given in PARTICULATES and data for the traffic activity. The output of the model UFPEM (UltraFine Particle Emission Model) is a sum of continuous distributions of ultrafine particles emissions per vehicle type (passenger cars and heavy duty vehicles), fuel (petrol and diesel) and average speed representative for urban, rural and highway driving.The results from the parameterization are compared with measured total number of ultrafine particles and size distributions in a tunnel in Antwerp (Belgium). The measured UFP concentration over the entire campaign shows a close relation to the traffic activity. The modelled concentration is found to be lower than the measured in the campaign. The average emission factor from the measurement is 4.29E + 14 #/km/veh whereas the calculated is around 30% lower. A comparison of emission factors with literature is done as well and in overall a good agreement is found.For the size distributions it is found that the measured distributions consist of three modes - Nucleation, Aitken and accumulation and most of the ultrafine particles belong to the Nucleation and the Aitken modes. The modelled Aitken mode (peak around 0.04-0.05 mu m) is found in a good agreement both as amplitude of the peak and the number of particles whereas the modelled Nucleation mode is shifted to smaller diameters and the peak is much lower that the observed.Time scale analysis shows that at 300 m in the tunnel coagulation and deposition are slow and therefore neglected.The UFPEM emission model can be used as a source term in dispersion models. (C) 2011 Elsevier B.V. All rights reserved.

Daily and seasonal variation in the total elemental, organic carbon (OC) and elemental carbon (EC) content and mass of PM2.5 were studied at industrial, urban, suburban and agricultural/rural areas. Continuous (optical Dustscan, standard tapered element oscillating micro-balance (TEOM), TEOM with filter dynamics measurement system), semi-continuous (Partisol filter-sampling) and non-continuous (Dekati-impactor sampling and gravimetry) methods of PM2.5 mass monitoring were critically evaluated. The average elemental fraction accounted for 2–6% of the PM2.5 mass measured by gravimetry. Metals, like K, Mn, Fe, Cu, Zn and Pb were strongly inter-correlated, also frequently with non-metallic elements (P, S, Cl and/or Br) and EC/OC. A high OC/EC ratio (2–9) was generally observed. The total carbon content of PM2.5 ranged between 3 and 77% (averages: 12–32%), peaking near industrial/heavy trafficked sites. Principal component analysis identified heavy oil burning, ferrous/non-ferrous industry and vehicular emissions as the main sources of metal pollution.