Nico Bleux

Exposure assessment of a cyclist to PM10 and ultrafine particles

Estimating personal exposure to air pollution is a crucial component in identifying high-risk populations and situations. It will enable policy makers to determine efficient control strategies. Cycling is again becoming a favorite mode of transport both in developing and in developed countries due to increasing traffic congestion and environmental concerns. In Europe, it is also seen as a healthy sports activity. However, due to high levels of hazardous pollutants in the present day road microenvironment the cyclist might be at a higher health risk due to higher breathing rate and proximity to the vehicular exhaust. In this paper we present estimates of the exposure of a cyclist to particles of various size fractions including ultrafine particles (UFP) in the town of Mol (Flanders, Belgium). The results indicate relatively higher UFP concentration exposure during morning office hours and moderate UFP levels during afternoon. The major sources of UFP and PM(10) were identified, which are vehicular emission and construction activities, respectively. We also present a dust mapping technique which can be a useful tool for town planners and local policy makers.

The Aeroflex: A Bicycle for Mobile Air Quality Measurements

Fixed air quality stations have limitations when used to assess peoples real life exposure to air pollutants. Their spatial coverage is too limited to capture the spatial variability in, e.g., an urban or industrial environment. Complementary mobile air quality measurements can be used as an additional tool to fill this void. In this publication we present the Aeroflex, a bicycle for mobile air quality monitoring. The Aeroflex is equipped with compact air quality measurement devices to monitor ultrafine particle number counts, particulate mass and black carbon concentrations at a high resolution (up to 1 second). Each measurement is automatically linked to its geographical location and time of acquisition using GPS and Internet time. Furthermore, the Aeroflex is equipped with automated data transmission, data pre-processing and data visualization. The Aeroflex is designed with adaptability, reliability and user friendliness in mind. Over the past years, the Aeroflex has been successfully used for high resolution air quality mapping, exposure assessment and hot spot identification.

Methodology for setup and data processing of mobile air quality measurements to assess the spatial variability of concentrations in urban environments.

A case study is presented to illustrate a methodology for mobile monitoring in urban environments. A dataset of UFP, PM2.5 and BC concentrations was collected. We showed that repeated mobile measurements could give insight in spatial variability of pollutants at different micro-environments in a city. Streets of contrasting traffic intensity showed increased concentrations by a factor 2-3 for UFP and BC and by <10% for PM2.5. The first quartile (P25) of the mobile measurements at an urban background zone seems to be good estimate of the urban background concentration. The local component of the pollutant concentrations was determined by background correction. The use of background correction reduced the number of runs needed to obtain representative results. The results presented, are a first attempt to establish a methodology for setup and data processing of mobile air quality measurements to assess the spatial variability of concentrations in urban environments.

Wintertime spatio-temporal variation of ultrafine particles in a Belgian city

Simultaneous measurements of ultrafine particles (UFPs) were carried out at four sampling locations situated within a 1 km(2) 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%.

Mass and ionic composition of atmospheric fine particles over Belgium and their relation with gaseous air pollutants

Mass, major ionic components (MICs) of PM2.5, and related gaseous pollutants (SO2, NO(x), NH3, HNO2, and HNO3) were monitored over six locations of different anthropogenic influence (industrial, urban, suburban, and rural) in Belgium. SO4(2-), NO3-, NH4+, and Na+ were the primary ions of PM2.5 with averages diurnal concentrations ranging from 0.4-4.5, 0.3-7.6, 0.9-4.9, and 0.4-1.2 microg m(-3), respectively. MICs formed 39% of PM2.5 on an average, but it could reach up to 80-98%. The SO2, NO, NO2, HNO2, and HNO3 levels showed high seasonal and site-specific fluctuations. The NH3 levels were similar over all the sites (2-6 microg m(-3)), indicating its relation to the evenly distributed animal husbandry activities. The sulfur and nitrogen oxidation ratios for PM2.5 point towards a low-to-moderate formation of secondary sulfate and nitrate aerosols over five cities/towns, but their fairly intensive formation over the rural Wingene. Cluster analysis revealed the association of three groups of compounds in PM2.5: (i) NH4NO3, KNO3; (ii) Na2SO4; and (iii) MgCl2, CaCl2, MgF2, CaF2, corresponding to anthropogenic, sea-salt, and mixed (sea-salt + anthropogenic) aerosols, respectively. The neutralization and cation-to-anion ratios indicate that MICs of PM2.5 appeared mostly as (NH4)2SO4 and NH4NO3 salts. Sea-salt input was maximal during winter reaching up to 12% of PM2.5. The overall average Cl-loss for sea-salt particles of PM2.5 at the six sites varied between 69 and 96% with an average of 87%. Principal component analysis revealed vehicular emission, coal/wood burning and animal farming as the dominating sources for the ionic components of PM2.5.

Appraisal of measurement methods, chemical composition and sources of fine atmospheric particles over six different areas of Northern Belgium

Daily and seasonal variation in the total elemental, organic carbon (OC) and elemental carbon (EC) content and mass of PM(2.5) 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 PM(2.5) mass monitoring were critically evaluated. The average elemental fraction accounted for 2-6% of the PM(2.5) 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 PM(2.5) 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.

Speciation and fractionation of nickel in airborne particulate matter: comparison between selective leaching and XAS spectroscopy

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. NiSO4·6H2O and Ni(NO3)2·6H2O). 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.

Speciation of inorganic arsenic in particulate matter by combining HPLC/ICP-MS and XANES analyses

Inorganic arsenic species in ambient particulate matter (PM10 and PM2.5) have been determined in an urban area, in the vicinity of a metallurgical industrial plant. The developed high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC/ICP-MS) method allows monitoring of particulate As(III) and As(V)-species, with a limit of quantification of 0.34 ng m−3 As(III) and 0.23 ng m−3 As(V), respectively. Good agreement was obtained between the sum of the concentrations of As(III) and As(V) determined by HPLC/ICP-MS and the total As concentrations determined by XRF, indicating a complete extraction of the As species. During the measuring campaigns for PM10 and PM2.5, a significant conversion (oxidation) up to 54% of exogenous spiked As(III) was observed. The total amount of the spiked As(III) was well-recovered (PM10 and PM2.5 on average 108% and 101%, respectively). The extraction of the filter in combination with the sampled air matrix is likely to induce the As(III) conversion. The average measured As concentration in PM10 during a 40-day monitoring campaign (30 ng m−3) at a hot spot location is above the European target value of 6 ng m−3. The measured As concentration in PM2.5 was half the value of the measured concentration in PM10 and no relative enrichment of total As was observed in either particulate matter fractions. However, in PM10, As(V) was the main component, while in PM2.5, As(III) was the dominant species. During the monitoring campaign, the fraction of particulate As(III) varied between 19 and 61% in PM10 and a trend towards a higher fraction of As(III) with increasing concentration of total As was observed. XANES and XRD analyses were used for the identification of arsenic species in local PM sources and confirmed the presence of Ca3Sr2(AsO4)2.5(PO4)0.5(OH), As2O3 and As2O5 species.

Exposure of Cyclists to Ultra Fine Particles

We present results from the Belgian SHAPES project, a policy oriented research project in which all major cycling related health risks are evaluated in an objective way. In this paper we present a methodology to estimate the exposure of ultra fine particulate matter (UFP numbers) to cyclists and results of measurements performed while cycling in real traffic. Methodology validation trials indicate that measured concentrations of UFP are independent of sampling direction (relative to cycling direction) and sampling height (between 0.9 and 1.6 m). Cyclists are exposed to frequent but short bursts of UFP, associated with motorized vehicles, even when cycling on the upwind side of the road. Concentrations range from below 10,000 to 500,000 cm−3. Peaks are related to the exhaust emissions of specific vehicles. UFP numbers quickly decrease with increasing distance from the road (approximately –6% m−1). There was no evidence for an effect of wind direction and dispersion at short range seems to be caused primarily by turbulence. Using this new methodology SHAPES will be able to determine the dose of UFP inhaled by cyclists compared to car users.

Do ICP-MS based methods fulfill the EU monitoring requirements for the determination of elements in our environment?

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.