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The sanitation of concrete structures through dismantling of nuclear buildings is complicated by the radiological threat associated with the airborne release of fine dust. This is the reason why the aerosol release fraction (ARF) associated with mechanical removal of concrete structure containing radioactivity needs to be accurately evaluated to implement efficient radiological survey. We characterize experimentally the ARF resulting from milling operations on a standard concrete slab in a confined experimental chamber using an industrial scarifying machine. Our results reveal a significant production of fine aerosol particles with a mass median aerodynamic diameter close to 4 µm and which mineralogical composition is dominated by calcium and silica compounds. The ARF measured when a vacuum suction device is used to confine the dust production close to the source is on the order of 5×10-4; the maximum ARF estimated when no suction device is used is on the order of 0.5.

Dans ce contexte, de multiples bio-impacteurs sous la forme de buses un étage rondes ont été conçues, fabriquées et caractérisées à partir de considérations classiques dans la conception des impacteurs. Ensuite, des aérosols et bio-aérosols de différentes origines et tailles ont été impactées sur du silicium (lisse) et du silicium nano-structuré pour évaluer les caractéristiques de déposition de ces aérosols sur de telles surfaces. Les résultats expérimentaux montrent que la taille des particules volatiles déterminent les caractéristiques de déposition par un procédé de rebond et de ré-entrainement (effet de rebond). L'efficacité de collecte dans la première zone d'impact a été estimée. Le silicium nano-structuré permet de réduire l'effet de rebond des particules micrométriques grâce à ses piliers pointus en cassant les particules en plus petits fragments ce qui a comme conséquence de confiner la déposition sous la buse. Cette déposition localisée peut facilement être alignée avec un micro-capteur. Ainsi cette étude suggère que les capteurs MEMS de masse inertielle sont adaptés pour la détection de particules de tailles micrométriques.

The analytical performance of high-resolution scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) for accurate determination of the size, size distribution, qualitative elemental analysis of nanoparticles (NPs) was systematically investigated. It is demonstrated how powerful high-resolution SEM is by using both mono- and bi-modal distributions of SiO2 airborne NPs collected on appropriate substrates after their generation from colloidal suspension. The transmission mode of the SEM (TSEM) is systematically employed for NPs prepared on thin film substrates such as transmission electron microscopy grids. Measurements in the transmission mode were performed by using a “single-unit” TSEM transmission setup as manufactured and patented by Zeiss. This alternative to the “conventional” STEM detector consists of a special sample holder that is used in conjunction with the in-place Everhart–Thornley detector. In addition, the EDX capabilities for imaging NPs, highlighting the promising potential with respect to exploitation of the sensitivity of the new large area silicon drift detector energy dispersive X-ray spectrometers were also investigated. The work was carried out in the frame of a large prenormative VAMAS (Versailles Project on Advanced Materials and Standards) project, dedicated to finding appropriate methods and procedures for traceable characterization of NP size and size distribution.

Carbon nanotube-based poly(methyl methacrylate) and polyamide-6 nanocomposites have been investigated using various techniques within the framework of the NANOFEU project. Scanning transmission electron microscopy was used to characterize morphologies of composites, while fire properties were studied using cone calorimeter and pyrolysis combustion flow microcalorimeter. The study focused particularly on composition and microstructure of gaseous and aerosol products. Morphology of ultrafine particles released from the combustion of nanocomposites was studied using cascade impactor and atomic force microscopy. Fire behaviour has been interpreted in relation with the degradation mechanisms specifically induced by the presence of carbon nanotubes. Copyright © 2012 John Wiley & Sons, Ltd.

Nanoparticles with size in the range from 10 nm to 300 nm and from three different materials (Au 10 nm, Ag 20 nm, and PSL 30 nm, 100 nm and 300 nm) were used in this supplementary comparison. The selected nanoparticles meet the requirements of different measurement methods such as Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and Differential Mobility Analyzer (DMA), Small Angle X-Ray Scattering and for forth. All 37 participating laboratories returned results, but not all laboratories were able to perform measurement of all 5 nanoparticles. In order to determine the degree of equivalence (DOE), two reference values were considered in this comparison: the method dependent reference value (MRV) and the global reference value (GRV). The MRVs were determined for different measurement methods according to the corresponding reported uncertainties and measurement values from the participants. Each measurement method owns its own MRV. Since the measurement data from DLS were very different from and inconsistent with the measurement data from the other methods, the MRV for DLS was used in the En number calculation for the measurement data reported from the DLS method. The GRV was determined from the MRVs and their uncertainties of all the measurement methods except DLS, and was applied in the En number calculations for the measurement data reported from AFM, EM, DMA and SAXS methods. The assumption that the particles are spherical was commonly made in the nanoparticle measurements. Non-sphericity of particles, if exists, could have different impacts on different measurement methods. It is also important to note that the methods used are measuring mean diameters of a population of particles, not just a single particle, and that the meaning of the mean diameter could differ for different methods. Probably if participants include a different specific contribution in the uncertainty in a harmonized way, taking the non-cancelled method-dependent "systematic" errors into account, it may be easier to compare the results. KEY WORDS FOR SEARCH Nanoparticles; Atomic Force Microscopy (AFM); Transmission Electron Microscopy (TEM); Scanning Electron Microscopy (SEM); Dynamic Light Scattering (DLS); and Differential Mobility Analyzer (DMA); Small Angle X-Ray Scattering Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The objective of this work is to carry out an experimental investigation on the influence of different parameters such as liquid properties (viscosity and liquid-gas surface tension), impacting droplet properties (velocity vi and diameter di) and the thickness of liquid film on the emission of airborne particles produced by the impact of millimetre-size droplets onto a liquid film. Our results show that in the variation range studied, the increase of vi and di or the decrease in liquid film thickness produces an increase in the mean number of microdroplets emitted by impact in the size range 2-50 μm. Furthermore, it was also observed that an increase in viscosity involves a steep decrease in the mean number of microdroplets emitted. These microdroplets may be produced by the fingers pinching of the crown formed during impact. In the case of low surface tension liquid, the formation of bubbles involves high production of droplets smaller than 15 μm. The results presented here constitute a database of the micro-droplets produced to validate models of droplet impact outcomes. © 2009 Elsevier Ltd. All rights reserved.

The aim of this work is to carry out an experimental investigation into the generation of airborne microparticles when millimetric droplets of aqueous solutions impact onto a liquid film. Impact experiments using 3.9 mm diameter droplets were carried out for Weber numbers between 159 and 808, with a fixed Ohnesorge number of 2 × 10−3 and film parameters S f (the ratio between the thickness of the liquid film h film and the diameter of the impacting droplet d i) between 0.3 and 1. Observed results show that the deposition/splashing threshold is independent of the parameter S f in agreement with the data in the literature. The aerosol measurement results demonstrate the production of solid particles from the evaporation of secondary microdroplets with diameters less than 30 μm formed when splash occurs. The median diameter of these microdroplets is around 20 μm, corresponding to a value of d 50/d i = 5 × 10−3. Taken together, the results show that the mass and the number of particles emitted increase as the Weber number increases. Moreover, at a Weber number of 808, the results show that the mass and number of particles emitted increases as the parameter S f decreases. In this case, the mean number of microdroplets emitted per impact is equal to 14 for S f = 1 and equal to 76 for S f = 0.3.

Le TEOM-FDMS (Tapered Element Oscillating Microbalance with Filter Dynamics Measurement Systems) est un instrument de mesure tres repandu au sein du reseau national de surveillance de la qualite de l’air. A l’heure actuelle, cet appareil est etalonne a l’aide de masses etalons raccordees au SI mais dont les valeurs et les differences de masse ne sont pas representatives des masses particulaires atmospheriques prelevees. De plus, l’utilisation de ces masses etalons ne permet pas de prendre en compte un eventuel dysfonctionnement du systeme de prelevement en amont de la mesure de la masse et du systeme de filtration intrinseque au TEOM-FDMS. Par consequent, une nouvelle methode d’etalonnage a ete developpee pour les TEOM-FDMS de par la mise en place d’un systeme portable de generation de particules ayant des concentrations massiques connues et stables dans le temps. Cet article presente la caracterisation de la reproductibilite globale de ce generateur portable en terme de gamme de masses de reference, son couplage avec differents types de TEOM-FDMS et la comparaison globale entre les masses particulaires de reference definies et les masses lues obtenues pour chaque TEOM-FDMS implique dans cette etude.

International audience; This work investigates the aerosols emitted during combustion of aircraft and naval structural composite materials (epoxy resin/carbon fibers and vinyl ester/glass fibers and carbon nanotubes). Combustion tests were performed at lab-scale using a modified cone calorimeter. The aerosols emitted have been characterized using various metrological devices devoted to the analysis of aerosols. The influence of the nature of polymer matrices, the incorporation of fibers and carbon nanotubes as well as glass reinforcements on the number concentration and the size distribution of airborne particles produced, was studied in the 5 nm–10 μm range. Incorporation of carbon fibers into epoxy resin significantly reduced the total particle number concentration. In addition, the interlaced orientation of carbon fibers limited the particles production compared to the composites with unidirectional one.The carbon nanotubes loading in vinyl ester resin composites influenced the total particles production during the flaming combustion with changes during kinetics emission. Predominant populations of airborne particles generated during combustion of all tested composites were characterized by a PN50 following by PN100–500.

Results of an interlaboratory comparison on size characterization of SiO2 airborne nanoparticles using on-line and off-line measurement techniques are discussed. This study was performed in the framework of Technical Working Area (TWA) 34 - "Properties of Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS) in the project no. 3 "Techniques for characterizing size distribution of airborne nanoparticles". Two types of nano-aerosols, consisting of (1) one population of nanoparticles with a mean diameter between 30.3 and 39.0 nm and (2) two populations of non-agglomerated nanoparticles with mean diameters between, respectively, 36.2-46.6 nm and 80.2-89.8 nm, were generated for characterization measurements. Scanning mobility particle size spectrometers (SMPS) were used for on-line measurements of size distributions of the produced nano-aerosols. Transmission electron microscopy, scanning electron microscopy, and atomic force microscopy were used as off-line measurement techniques for nanoparticles characterization. Samples were deposited on appropriate supports such as grids, filters, and mica plates by electrostatic precipitation and a filtration technique using SMPS controlled generation upstream. The results of the main size distribution parameters (mean and mode diameters), obtained from several laboratories, were compared based on metrological approaches including metrological traceability, calibration, and evaluation of the measurement uncertainty. Internationally harmonized measurement procedures for airborne SiO2 nanoparticles characterization are proposed. © 2013 Springer Science+Business Media Dordrecht.

The fire behavior and the characterization of solid and gaseous fire effluents of polymers [polymethyl methacrylate (PMMA) and polyamide-6 (PA-6)] filled with nanoparticles (silica, alumina, and carbon nanotubes) used to improve their flame retardancy were investigated. To determine the impact of these composites on the emission of airborne particles produced during their combustion in accidental fire scenarios, an experimental setup was developed to measure the mass distribution in the 30 nm–10 μm range, and the concentrations of submicrometric particles in the aerosol. Comparisons were made between unfilled and filled polymers, and the influence of filler surface treatments (silane-based), as well as combinations with a flame retardant [ammonium polyphosphate (APP)], was investigated. The presence of nano-oxides in PMMA shows a significant effect on the rate of particle emission with a decrease in the concentration of the emitted submicrometric particles. APP in PMMA led to a decrease in the mass fraction of ultrafine particles and an increase in the rate of submicrometric particle emission compared to filled compositions with nano-oxides. Atomic force microscopy was used as a complementary tool for the characterization of the particles emitted during combustion, allowing direct observation of nanoparticle morphology, detection of carbon nanotubes in the aerosol, and visualization of the effect of APP on nanoparticle morphology.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Technological advances in nanomaterials have allowed the development of new applications in industry, increasing the probability of finding airborne manufactured and engineered nano-objects in the workplace, as well as in ambient air. Scientific studies on health and environmental risks have indicated that airborne nano-objects in ambient air have potential adverse effects on the health of exposed workers and the general population. For regulatory purposes, ambient measurements of particulate matter are based on the determination of mass concentrations for PM10 and PM2.5, as regulated in the European Directive 2008/50/EC. However, this legislation is not suitable for airborne manufactured and engineered nano-objects. Parameters characterising ultrafine particles, such as particle number concentration and size distribution, are under consideration for future health-based legislation, to monitor workplaces and to control industrial processes. Currently, there are no existing regulations covering manufactured airborne nano-objects. There is therefore a clear, unaddressed need to focus on the toxicology and exposure assessment of nano-objects such as titanium dioxide (TiO2), which are manufactured and engineered in large quantities in industry. To perform reliable toxicology studies it is necessary to determine the relevant characteristics of nano-objects, such as morphology, surface area, agglomeration, chemical composition, particle size and concentration, by applying traceable methods. Manufacturing of nanomaterials, and their use in industrial applications, also require traceable characterisation of the nanomaterials, particularly for quality control of the process. The present study arises from the OECD WPMN sponsorship programme, supported by the French Agency for Environmental and Occupational Health Safety (ANSES), in order to develop analytical methods for the characterization of TiO2 nanoparticles in size and count size distribution, based on different techniques to characterize five different manufactured TiO2 nanoparticles. In this study, different measurement techniques have been implemented: Transmission Electron Microscopy (TEM), Scanning Mobility Particle Sizer (SMPS) and Aerodynamic Particle Sizer (APS). The TEM results lead to a relatively good agreement between data from the manufacturer and our characterizations of primary particle size. With regard to the dustiness, the results show a strong presence of agglomerates / aggregates of primary particles and a significant presence of emitted airborne nanoparticles with a diameter below 100 nm (composed of isolated primary particles and small aggregates / agglomerates formed from a few primary particles): the number proportion of these particles varies from 0 to 44 % in the measurement range 14-360 nm depending on the types of powders and corrections of measurements.

Scanning Mobility Particle Sizer (SMPS) is a high resolution nanoparticle sizing system that has long been hailed as the researcher's choice for airborne nanoparticle size characterization for nano applications including nanotechnology research and development. SMPS is widely used as the standard method to measure airborne particle size distributions below 1 m. It is composed of two devices: a Dierential Mobility Analyzer (DMA) selects particle sizes thanks to their electrical mobility and a Condensation Particle Counter (CPC) enlarges particles to make them detectable by common optical counters. System raw data represent the number of particles counted over several classes of mobility diameters. Then, common inversion procedures lead to the estimation of the aerosol size distribution. In this paper, we develop a methodology to compute the uncertainties associated with the estimation of the size distribution when several experiences have been carried out. The requirement to repeat the measure ensures a realistic variability on the simulated data to be generated. The work we present consists in considering both the uncertainties coming from the experimental dispersion and the uncertainties induced by the lack of knowledge on physical phenomena. Experimental dispersion is quantied with the experimental data while the lack of knowledge is modelled via the existing physical theories and the judgements of experts in the eld of aerosol science. Thus, running Monte-Carlo simulations give an estimation of the size distribution and its corresponding condence region.

Day after day, new applications using nanoparticles appear in industry, increasing the probability to find these particles in the workplace as well as in ambient air. As epidemiological studies have shown an association between increased particulate air pollution and adverse health effects in susceptible members of the population, it is particularly important to characterize aerosols emitted by different sources of emission, during the combustion of composites charged with nanoparticles for example. The present study is led in the framework of the NANOFEU project, supported by the French Research Agency (ANR), in order to characterize the fire behaviour of polymers charged with suitable nanoparticles and make an alternative to retardant systems usually employed. To determine the impact of these composites on the emission of airborne particles produced during their combustions, an experimental setup has been developed to measure the mass distribution in the range of 30 nm – 10 μm and the number concentration of submicrometric particles of the produced aerosol. A comparison is performed on the aerosol emitted during the combustion of several polymers alone (PMMA, PA-6), polymers containing nanofillers (silica, alumina, and carbon nanotubes) and polymers containing both nanofillers and a conventional flame retardant system (ammonium polyphosphate). The results on the morphology of particles were also investigated using AFM.