Innovative tools and modeling methodology for impact prediction and assessment of the contribution of materials on indoor air quality

International audienceBackground: The combination of more and more airtight buildings and the emission of formaldehyde and other volatile organic compounds (VOCs) by building, decoration and furniture materials lead to lower indoor air quality. Hence, it is an important challenge for public health but also for the preservation of cultural heritage, as for example, artworks in museum showcases and other cultural objects. Indeed, some VOCs such as organic acids or carbonyl compounds may play a role in the degradation of some metallic objects or historic papers. Thus, simple and cost effective sampling tools are required to meet the recent and growing demand of on-site diagnostic of indoor air quality , including emission source identification and their ranking.Results: In this aim, we developed new tools based on passive sampling (Solid-Phase Micro Extraction, SPME) to measure carbonyls compounds (including formaldehyde) and other VOCs and both in indoor air and at the material/ air interface. On one hand, the coupling of SPME with a specially designed emission cell allows the screening and the quantification of the VOCs emitted by building, decoration or furniture materials. On the other hand, indoor air is simply analysed using new vacuum vial sampling combined with VOCs pre-concentration by SPME. These alternative sampling methods are energy free, compact, silent and easy to implement for on-site measurements. They show satisfactory analytical performance as detection limits range from 0.05 to 0.1 µg m −3 with an average Relative Standard Deviation (RSD) of 18 %. They already have been applied to monitoring of indoor air quality and building material emissions for a 6 months period. The data obtained were in agreement with the prediction of a physical monozonal model which considers building materials both as VOC sources and sinks and air exchange rate in one single room ("box model").Conclusion: Results are promising, even if more data are required to complete validation, and the model could be envisaged as a predictive tool for indoor air quality. This new integrated approach involving measurements and mod-eling could be easily transposed to historic environments and to the preservation of cultural heritage

Assessment of VOCs Material/Air Exchanges of Building Products Using the DOSEC®-SPME Method

ACTInternational audienceUsing low emissive materials in building is an effective way to reduce indoor concentrations of pollutants such as VOCs. Material emissions are assessed by the ISO 16000-9 standard. This procedure is time-consuming and is not suitable for on-site measurements. This work aimed in assessing an alternative method, DOSEC\textregistered-SPME, for simple measurements. To validate it, emissions of 30 materials were characterized by both ISO 16000-9 and DOSEC\textregistered-SPME. A first correlation was found between the two methods for formaldehyde emissions of raw materials. This encouraging result allows considering the development of new decision making tools for the selection of healthy building materials

Simple analysis of odorous fatty acids in distillery effluents by capillary electrophoresis

The separation of short-chain carboxylic acids using capillary electrophoresis was already presented in several previous studies. As this method appears as a simple and fast alternative to more classical chromatographic approaches, this paper describes its application to the analysis of malodorous fatty acids in distillery effluents. The operating conditions were modified in order to improve the sensitivity. A 100 $\mu$m ID capillary combined with injection by electromigration led to detection limits in aqueous samples from 10 to 45 $\mu$g.L$^{-1}$. The ability of this method to analyse air samples was also examined. The detection limits obtained are in the order of $\mu$g.m$^{-3}$. This methodology was then applied to monitor the olfactory pollution of a distillery. The results obtained enabled a modification of the process to be proposed in order to reduce the malodorous emissions

New sampling device for on-site measurement of SVOC gas-phase concentration at the emitting material surface

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An Original Method Using a Passive Flux Sampler to Characterize the Gas-Phase Boundary Layer on the Surface of Indoor Materials

ACTInternational audienc

Characteristics of formaldehyde emissions from indoor materials assessed by a method using passive flux sampler measurements

International audienceA method was developed and tested to characterize the gas-phase boundary layer developing on the surface of seven indoor materials from formaldehyde emission measurements carried out under environmental chamber conditions using passive flux samplers having different diffusion lengths. This indirect approach consistently provides many assessed values of gas-phase boundary layer thickness with a mean and range of 31.6 +/- 17.4 mm. These experiments also yield other information like the gas concentration on the material surface as well as the concentration gradient inside the gas-phase boundary layer. Linear relationships were found between formaldehyde gas concentration on the material surface, the concentration gradient inside the gas-phase boundary layer and the emission rate. Data and relationships should be useful for parameterizing and modeling formaldehyde emissions from indoor surfaces

Ion-exchange extraction of organic acids in water samples. Study of the influential factors and interactions

The objective is to concentrate organic acid traces in water samples. The influence of several parameters and their interactions on the adsorption of organic acids on anion exchange resins was studied. A complete factorial design 24 was hence performed. The measured response corresponds to the maximal percolation volume and the studied parameters were the nature and the mass of the resin, the percolation flow-rate and the ionic strength of the analysed water. The results shown that the percolation flow-rate is significant but not really important compared to the resin mass and to the nature of water. Indeed, the sample inorganic anions can compete with organic acids. This adsorption competition appears to be more important when a macroporous resin is used. A “gel-type" resin could be therefore better adapted to the extraction of organic acids in water samples

Hierarchical cluster analysis of carbonyl compounds emission profiles from building and furniture materials

International audienceEmission profiles of carbonyl compounds from twenty-three indoor materials were assessed by chamber tests and compared by means of a hierarchical cluster analysis. This multivariate method provides a partition into six clusters of materials having statistically similar chemical profiles. Formaldehyde is the most dominant component of emissions mainly related to two types of wood composite products (chipboards and medium-density fibreboards (MDF)) and one finishing plaster. The analysis of clusters reveals that the emission profiles of materials belonging to a same category can have various degrees of variability. Some common pressed-wood products as chipboards and medium-density fibreboards have relatively uniform profiles characterized by its unique emission of formaldehyde. On the contrary, the profiles of Oriented Strand Boards (OSB) and finishing plasters appear very heterogeneous and unspecific in terms of relative dominance between different carbonyl compounds. The finishing plasters are identified as sources of carbonyl compounds (formaldehyde and acetaldehyde, especially). These finishing products have not yet been listed as potential formaldehyde and acetaldehyde emitters. According to these results, the wood composite products can also be ranked in the decreasing order of formaldehyde emission as follows: Chipboards > MDFs > Plywoods > OSBs. In light of these results, more systematic surveillance program on the emissions from materials should be set up by Public Health services to require or request product changes for building and furnishing applications

Improvement of the Performance of a Simple Box Model Using CFD Modeling to Predict Indoor Air Formaldehyde Concentration

ACLInternational audienc