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The oxidative potential (OP) is defined as the ability of inhaled PM components to catalytically/non-catalytically generate reactive oxygen species (ROS) and deplete lung antioxidants. Although several studies have measured the OP of particulate matter (PM OP) soluble components using different antioxidants under neutral pH conditions, few studies have measured PM OP with acidic lung fluids. This study provides new insights into the use of acidic rather than neutral fluids in OP assays. Thus, the first aim of this study was to clarify the effect of using an acidic lung fluid on ascorbic acid (AA) depletion. This was achieved by measuring the oxidative potential (OP-AA) of individual compounds known to catalyze the AA oxidation (CuSO4, CuCl2, and 1,4-NQ) in artificial lysosomal fluid (ALF, pH 4.5), a commonly used acidic simulated lung fluid, and in a neutral fluid (phosphate-buffered saline (PBS1x), pH 7.4). Our results from these individual compounds showed a significant decrease of OP-AA in the acidic fluid (ALF) with respect to the neutral fluid (PBS). Then, the second aim of this work was to investigate whether the OP-AA assay could be applied to PM2.5 samples extracted in acidic conditions. For this purpose, OP-AA and bioaccessible concentrations of metal(loid)s (V, Mn, Fe, Ni, Cu, Zn, As, Mo, Cd, Sb, and Pb) of PM2.5 samples collected in an urban-industrial area that were extracted in ALF were analyzed. The mean volume-normalized OP (OP-AAv) value was 0.10 ± 0.07 nmol min−1 m−3, clearly lower than the values found in the literature at neutral pH. OP-AAv values were highly correlated with the ALF-bioaccessible concentration of most of the studied metal(loid)s, mainly with Cu and Fe. [ABSTRACT FROM AUTHOR]

Byline: F. Ledoux, D. Courcot, L. Courcot, A. Aboukais, E. Puskaric Aerosols samplings by bulk filtration and by use of a high volume cascade impactor were performed taking into account wind directions simultaneously at an urban and a rural site in Northern France. Fifteen major and trace species were considered to study characteristics of the particles collected. Evolution of the Weighted Mean Diameter vs. the wind direction, profiles of the Mass Size Function (MSF), values of the dry deposition fluxes, distribution between the coarse particles (>1 μm) and the fine particles (4+ and SO42−, NO3− are discussed in this work.

The consequences of indoor and outdoor air pollution on human health are of great concern nowadays. In this study, we firstly evaluated indoor and outdoor air pollution levels (CO, CO 2 , NO, NO 2 , PM 10) at an urban site in Dakar city center and at a rural site. Then, the individual exposure levels to selected pollutants and the variations in the levels of biomarkers of exposure were investigated in different groups of persons (bus drivers, traders working along the main roads and housemaids). Benzene exposure levels were higher for housemaids than for bus drivers and traders. High indoor exposure to benzene is probably due to cooking habits (cooking with charcoal), local practices (burning of incense), the use of cleaning products or solvent products which are important emitters of this compound. These results are confirmed by the values of S-PMA, which were higher in housemaids group compared to the others. Urinary 1-HOP levels were significantly higher for urban site housemaids compared to semirural district ones. Moreover, urinary levels of DNA oxidative stress damage (8-OHdG) and inflammatory (interleukin-6 and -8) biomarkers were higher in urban subjects in comparison to rural ones. The air quality measurement campaign showed that the bus interior was more polluted with PM 10 , CO, CO 2 and NO than the market and urban or rural households. However, the interior of households showed higher concentration of VOCs than outdoor sites confirming previous observations of higher indoor individual exposure level to specific classes of pollutants. Image 1 • Indoor organic volatile pollution higher than outdoor one. • Highest urinary levels of oxidative stress and inflammatory biomarkers in urban subjects. • Importance of indoor air pollution on the benzene metabolite S-PMA. • Relevance of indoor habit to determine the exposure levels to selected VOCs. • Correlation of biomarker of exposure with selected VOCs. Outdoor and indoor air pollution analysis and human biomarker exposure evaluation. [ABSTRACT FROM AUTHOR]

Abstract: This work concerns atmospheric particles (PM 2.5) collected in the surroundings of rural, urban and industrial areas. The investigation zone chosen for the study is Dunkirk (North of France), a highly industrialised city located along the North sea, where various activities are present such as metallurgy, petrol refineries and other chemical companies but also an important city with 210 000 inhabitants and two highly loaded motorways. Comparisons with a rural area were carried out. Physicochemical analysis of particulate matter was undertaken to propose parameters that could be used to distinguish the various sources and also to provide chemical elements for interpretation of future toxicological studies. This paper focuses on both organic and inorganic pollutants: Polycyclic Aromatic Hydrocarbons (PAH), paraffins, Volatile Organic Compounds (VOC), heavy metals and major soluble compounds (anionic and cationic). [Copyright &y& Elsevier]

Diesel soot and reference carbon black samples have been characterised by analysis of the organic compounds fraction and determination of textural characteristics (specific area). The potential to eliminate such carbonaceous particles has been investigated using a Cu/ZrO2 solid catalyst promoted by potassium additives. The reactivity of soot samples depends on the organic compounds content. In general, Cu-K/ZrO2 catalyst is able to lower significantly the soot oxidation temperature of almost 200°. This high activity is related to the ability of potassium to interact with copper species and to favour the release of active oxygen from the catalyst. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the deposition of Cu and K elements on zirconia was studied in the oxidation of a carbon black (CB), considered as a model of diesel soot. Catalytic tests were carried out using CB–catalyst mixtures prepared under loose and tight contact conditions. The potassium-containing catalysts exhibited high activity in loose contact that differed slightly from that obtained in tight contact. The introduction of both Cu and K on ZrO2 provided synergistic effects in the CB oxidation. It is proposed that these systems can release active oxygen species to oxidize CB even in the absence of gaseous oxygen. Consequently, (CB–catalyst) loose contact mixtures treated at different temperatures under Ar flow were characterized by electron paramagnetic resonance and temperature-programmed reduction measurements. The presence of potassium favours contact between the catalyst and CB and enhances the catalyst''s ability to release active oxygen species. In K/ZrO2, it yields an increase in the amount of Zr3+ ions, which appear to be stabilized mainly in monoclinic ZrO2. In Cu-K/ZrO2 catalysts, the potassium promoter preferentially interacts with the supported copper(II) species and favours their participation following a redox mechanism. [Copyright &y& Elsevier]

This work is devoted to the factorization of an observation matrix into additive factors, respectively a contribution matrix G and a profile matrix F which enable to identify many pollution sources. The search for G and F is achieved through Non-negative Matrix Factorization techniques which alternatively look for the best updates on G and F. These methods are sensitive to noise and initialization, and-as for any blind source separation method-give results up to a scaling factor and a permutation. A Weighted Non-negative Matrix Factorization extension has also been proposed in the literature, so that different standard deviations of the data matrix components are taken into account. However, some estimated profile components may be inconsistent with practical experience. To prevent this issue, we propose an informed Non-negative Matrix Factorization, where some components of the profile matrix are set to zero or to a constant positive value. A special parametrization of the profile matrix is developed in order to freeze some profile components and to let free the other ones. The problem amounts to solve a family of quadratic sub-problems. A Maximization Minimization strategy leads to some global analytical expressions of both factors. These techniques are used to estimate source contributions of airborne particles from both industrial and natural influences. The relevance of the proposed approach is shown on a real dataset. [ABSTRACT FROM AUTHOR]

Abstract: To identify the nature of active paramagnetic species involved in the carbon black (CB) oxidation, an Electron Paramagnetic Resonance (EPR) study of (CB–ZrO2) and (CB–Cu/ZrO2) loose contact mixtures treated under argon flow has been undertaken. In the presence of pure zirconia catalysts, it was found that ZrO2 interacts with CB and can be reduced into Zr3+ formed in tetragonal phase of this oxide support. In parallel, several EPR signals assigned to carbonaceous radicals were detected: i) carbonaceous radicals on CB surface, ii) radicals located at the CB–ZrO2 interface and iii) oxygen deficit carbonaceous radicals observed at high treatment temperature. The carbonaceous signals disappeared completely after CB oxidation in agreement with a regeneration of the catalyst treated under air. For copper supported on zirconia catalysts, oxygen surrounding isolated Cu(II) species and oxygen from tetragonal ZrO2 lattice are involved in carbon black oxidation. The phenomenon is reversible and this catalyst is also regenerated by air. Carbonaceous radical signals were also observed for (CB–Cu/ZrO2) mixture and their intensity decrease versus temperature appeared in good agreement with the better activity of Cu/ZrO2 compared to pure ZrO2. [Copyright &y& Elsevier]