In the present work, we investigate the effect of weathering duration on a commercial photocatalytic nanocoating on the basis of its nanoparticle emission tendency into two media, air and water. It is found that increased weathering duration results in stepwise structural deterioration of the nanocoating, which in turn decreases the nanocoating life, changes the nanocoating removal mechanism, and increases the particle emission concentration. Emission of free TiO2 nanoparticles is found to be weathering duration dependent. Three quantities are introduced: emission transition pace (ETP), stable emission level (SEL), and stable emission duration (SED). By linear extrapolation of these quantities from short weathering durations, complete failure of the nanocoatings can be predicted and, moreover, the potential increase of nanoparticles release into the air.

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Transmission electron microscopy (TEM) coupled with energy-dispersive X-ray (EDX) offers a very comprehensive tool for individual particle analysis allowing the determination of size, morphology, specific surface, and elemental composition. This information is needed in aerosol studies, especially in the field of nanomaterials. However, observations with TEM require a controlled sampling on an adapted analysis support, namely TEM grid. Techniques allowing sampling on TEM grids are of great interest to aerosol analysis. Indeed, sample preparation is not required, thereby gaining time and avoiding a risk for the sample to be altered. The present study evaluates the efficiency of a new particle collection technique based on filtration through one class of TEM-dedicated supports, namely TEM porous grids. Two types of porous grids, considered as the best on the market for this application, have been put to the test: the "Quantifoil" type porous grid, which has a regular structure, and the "Holey" type (Agar Scientific, Stansted, Essex, England). A filter holder has been developed specifically for this application, the MPS R (Mini-Particle Sampler R , Ecomesure, Janvry, France). Experimental tests have been carried out with a flow rate of 0.3 L·min −1. They show that the collection is operational in the 5-nm to 150-nm size range, with a minimum efficiency of 15-18% around 30 nm. Simulation confirms these results and shows an increased efficiency even below 5 nm and beyond 150 nm. The filter holder MPS R designed in this study is a low-cost, portable, versatile, and easy-to-use tool.

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The potential health effects of fine and ultrafine particles are of increasing concern. A better understanding of particle characteristics and dispersion behavior is needed. This study aims at characterizing spatial and temporal variations in fine and ultrafine particle dispersion after emission from a model source in an experimental house. Particles emitted by an incense stick burning for 15 min were characterized. Number concentration, specific surface area and mass were measured. Partial chemical analysis of particles was also realized. Near the burning incense stick, the maximum concentration was 25,500 particles/cm(3); the indoor PM(2.5) concentration reached 197 microg/m(3), and the specific surface area concentration was 180 microm(2)/cm(3). The estimated incense smoke density was 1.1 g/cm(3). Time of Flight Aerosol Mass Spectrometer measurements indicated that the organic fraction was predominant in the aerosol mass detected, and other minor components identified were K(+), NO(3)(-), and Cl(-). The combustion of an incense stick in the living room was associated with significant modifications of the concentrations of particles measured in the different rooms of the house. This demonstration of pollution by particle dispersion by a model source of moderate intensity may have significant implications in terms of assessment of indoor exposure to such particles. Practical Implications The particles emitted in a domestic environment by a source of moderate intensity such as burning incense disperse throughout the house, even in rooms with closed doors and in rooms as far away as the next floor. This dispersion has significant implications in terms of evaluating human indoor exposure to fine and ultrafine particles.