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

Comparative analysis of formaldehyde and toluene sorption on indoor floorings and consequence on Indoor Air Quality

International audienceIndoor surfaces may be adsorptive sinks with the potential to change Indoor Air Quality. To estimate this effect, the sorption parameters of formaldehyde and toluene were assessed on five floorings by an experimental method using solid‐phase microextraction in an airtight emission cell. Adsorption rate constants ranged from 0.003 to 0.075 m·h−1, desorption rate constants from 0.019 to 0.51 h−1, and the partition coefficient from 0.005 to 3.9 m, and these parameters vary greatly from one volatile organic compound/material couple to another indicating contrasted sorption behaviors. A rubber was identified as a sink of formaldehyde characterized by a very low desorption constant close to 0. For these sorbent floorings identified, the adsorption rates of formaldehyde are from 2 to 4 times higher than those of toluene. Two models were used to evaluate the sink effects of floorings on indoor pollutant concentrations in one room from different realistic conditions. The scenarios tested came to the conclusion that the formaldehyde sorption on one rubber (identified as a sink) has a maximum contribution from 15% to 21% for the conditions of low air exchange rate. For other floorings, the sorption has a minor contribution less than or equal to 5%, regardless of the air exchange rate

Modeling breakthrough curves of volatile organic compounds on activated carbon fibers

International audienceGranular activated carbon (GAC) and more recently activated carbon fibers (ACF) are used for the treatment of volatile organic compounds (VOC) in industrial processes. The purpose of this study was to investigate the adsorption kinetics of ACF to eliminate VOC from polluted air. This approach is carried out by modeling experimental breakthrough curves with two kinds of models: an equilibrium model and a mass transfer model based on a linear driving force (LDF) in conjunction with the Langmuir equilibrium model. The results show the influence of the intraparticle diffusion on the adsorption kinetics of ACF, in spite of their small fiber diameter. Moreover, external diffusion kinetics is fast because of the influence of the large external surface area of ACF on the VOC mass transfer

Field Investigation on the Indoor Sinks of Formaldehyde

ACTInternational audienc

Potential of static sampling using solid-phase microextraction for the assessment of formaldehyde sorption on building materials

International audienceFormaldehyde is considered as a priority pollutant of indoor air due to its numerous indoor sources and health impact. Due to its physico-chemical properties, the interaction of gaseous formaldehyde with material surfaces is suspected to play an important role in the distribution and fate of this compound indoors. This paper proposes an experimental method providing several parameters characterizing the material/air exchanges for formaldehyde namely, the adsorption and desorption rate constants (kam and kdm) and the material/air equilibrium partition coefficient (Ke) and the initial gas-phase concentration in equilibrium with the material surface (Cieq0). These parameters are assessed in a closed system (glass cell) containing the material and by a static sampling using solid-phase microextraction (SPME) fibers for measuring gaseous concentrations at the material surface during the emission and adsorption phases. Compared to the available methods of determining these parameters described in the literature, this method has the following advantages: (1) Taking into account of sorption on the inner walls of cell in the calculation of the material sorption parameters; (2) An analytical solution assessing the adsorption and desorption rate constants simultaneously from data of the adsorption phase; (3) An assessment of these sorption parameters under experimental conditions close to those encountered in indoor environments; (4) a satisfying reproducibility of the measured sorption parameters. The main performance of SPME sampling was assessed. The applicability of this method was proven to compare the sorption behavior of formaldehyde towards floor coverings

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

ACTInternational audienc

Relevance of microchamber test to predict the vehicle interior air quality: potential and limits

International audienc

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

ACLInternational audienc

Formaldehyde Emission Behavior of Building Materials: On-Site Measurements and Modeling Approach to Predict Indoor Air Pollution

ACLThe purpose of this paper was to investigate formaldehyde emission behavior of building materials from on-site measurements of air phase concentration at material surface used as input data of a box model to estimate the indoor air pollution of a newly built classroom. The relevance of this approach was explored using CFD modeling. In this box model, the contribution of building materials to indoor air pollution was estimated with two parameters: the convective mass transfer coefficient in the material/air boundary layer and the on-site measurements of gas phase concentration at material surfaces. An experimental method based on an emission test chamber was developed to quantify this convective mass transfer coefficient. The on-site measurement of gas phase concentration at material surface was measured by coupling a home-made sampler to SPME. First results had shown an accurate estimation of indoor formaldehyde concentration in this classroom by using a simple box model. \textcopyright 2014 Elsevier B.V