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

A lateral flow immunoassay for the rapid identification of Candida auris from isolates or directly from surveillance enrichment broths

IntroductionCandida auris is a recently discovered yeast with a multi-drug resistant profile associated with high mortality rates. The rapid identification of Candida auris in hospital settings is crucial to allow appropriate therapeutic and rapid implementation of infection management measures. The aim of this study was to develop a lateral flow immunoassay (LFIA) for the rapid identification of Candida auris.MethodsHighly specific monoclonal antibodies were obtained by immunizing mice with membrane proteins from Candida auris which were then used to develop a LFIA whose performance was assessed by testing 12 strains of Candida auris and 37 strains of other Candida species. Isolates were grown on either Sabouraud dextrose, CHROMagarTM Candida Plus or HardyCHROMTMCandida + auris agar plates. The strains were also cultured on salt sabouraud-dextrose with chloramphenicol or a commercially available Salt-Sabouraud Dulcitol Broth with chloramphenicol and gentamicin, and processed using a simple centrifugation protocol to recover a pellet. Finally, the colonies or yeast extract were transferred to the LFIA to determine the specificity and sensitivity of the assay.ResultsThe LFIA reached 100% specificity and sensitivity from solid agar plates. For both enrichment broths, some Candida non-auris species were able to grow, but the LFIA remained 100% specific. The use of a dextrose-based sabouraud broth resulted in earlier identification with the LFIA, with most of the Candida auris strains detected at 24 h.ConclusionThe developed LFIA prototype represents a powerful tool to fight the emerging threat of Candida auris. Clinical validation represents the next step

Neutralising Antibodies against Ricin Toxin

The Centers for Disease Control and Prevention have listed the potential bioweapon ricin as a Category B Agent. Ricin is a so-called A/B toxin produced by plants and is one of the deadliest molecules known. It is easy to prepare and no curative treatment is available. An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin. We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy. For this purpose, mouse monoclonal antibodies (mAbs) were produced against the two chains of ricin toxin (RTA and RTB). Seven mAbs were selected for their capacity to neutralise the cytotoxic effects of ricin in vitro. Three of these, two anti-RTB (RB34 and RB37) and one anti-RTA (RA36), when used in combination improved neutralising capacity in vitro with an IC50 of 31 ng/ml. Passive administration of association of these three mixed mAbs (4.7 µg) protected mice from intranasal challenges with ricin (5 LD50). Among those three antibodies, anti-RTB antibodies protected mice more efficiently than the anti-RTA antibody. The combination of the three antibodies protected mice up to 7.5 hours after ricin challenge. The strong in vivo neutralising capacity of this three mAbs combination makes it potentially useful for immunotherapeutic purposes in the case of ricin poisoning or possibly for prevention

Evaluation of a passive sampling method for the measurement of monoterpenes in indoor air

peer reviewedMonoterpenes are compounds naturally emitted by wooden materials. A preliminary study had demonstrated the occurrence of some monoterpenes in the timber frame constructions. Contrary to the active sampling, the passive sampling with Radiello® device simplifies the sampling step that is an interest in indoor environment. However, the knowledge of the sampling rate is necessary for quantification via the passive samplers Radiello®. Radiello® sampler with Tenax TA cartridge was evaluated for the 4-h concentration measurements of nine monoterpenes (α-pinene, β-pinene, d-limonene, Δ3-carene, camphene, carvone, 1,8-cineole, linalool and p-cymene). The performance parameters of the method (calibration curve, trueness, repeatability, blank level, stability of samples) were estimated. The sampling rates were first evaluated under the standard conditions in an exposure chamber. The influences of three environmental factors (temperature (T), relative humidity (RH) and concentration level (C)) on the sampling rates were also evaluated following a full factorial design at two factor levels (low and high). The monoterpenes concentrations in the exposure chamber were followed by an active sampling on tube Tenax TA. For both sampling devices, analyses were realized by TD-GC-MS. The results of this study demonstrated that the Radiello® device is suitable for the measurement of 5 of 9 studied monoterpenes. The sampling rates were defined by an equation including two factors, temperature and relative humidity. Temperature is found to be the most important factor leading to variability of the all monoterpene sampling rates. An equation allowing to estimate the sampling rate was established for every studied compound. Measurements of monoterpenes with the Radiello® device were then carried out on new wooden houses and compared with measurements obtained by active sampling on Tenax TA tubes

Identification des sources intérieures de composés organiques volatils et estimation de leur contribution aux teneurs observées dans les logements français

Les atmosphères intérieures se révèlent très riches en composés organiques volatils (COV). Ces substances forment un cocktail à risque dont la composition et les effets sur la santé restent encore méconnu. Cette complexité rend difficile l identification et la quantification des sources intérieures sur la qualité de l air. Cette thèse a pour but d établir des relations qualitatives et quantitatives entre les sources intérieures de COV et les teneurs observées dans des logements français. Le premier axe de travail porte sur le développement de la mesure passive pour déterminer les taux d émission en formaldéhyde (FA) et en acétaldéhyde des matériaux. Ce préleveur a été validé en laboratoire, puis utilisé in-situ, dans une campagne de mesures réalisée dans des chambres étudiantes. Ce diagnostic sur site montre que le mobilier et les matériaux du bâti de la pièce contribuent à part égale à la concentration intérieure en FA. L augmentation des émissions est clairement influencée par l élévation de la température. Un modèle d équilibre des masses basé sur les taux d émission mesurés a conduit à une prédiction satisfaisante des concentrations en FA dans les 24 lieux échantillonnés. Le second axe porte sur l analyse des profils chimiques de 60 logements. A partir d un screening des COV ; des classes homogènes de profils chimiques associés aux logements ont pu être établies. Des hypothèses sur les sources potentielles de ces composés ont été formulées et examinées sur la base des données de la littérature, des questionnaires descriptifs des logements et des émissions de matériaux et produits présents en environnement intérieur.Indoor atmospheres appear very rich in volatile organic compounds (VOC). These substances form a dangerous mix whose composition and effects on health remain still unknown. This complexity makes difficult the identification and the quantification of indoor sources on the indoor air quality. The purpose of this thesis is to establish qualitative and quantitative relationship between VOC indoor sources and the concentrations observed in French dwellings. The first axis of this work deals with the development of passive measurement to determine the formaldehyde (FA) and acetaldehyde emission rates of materials. This sampler was validated in laboratory, then used in-situ, in a batch of measurements carried out in student rooms. This diagnosis on site shows that the furniture and the building materials contribute equally to the indoor concentration in FA. The increase of the emissions is clearly influenced by the rise in the temperature. A balance mass model based on the measured emission rates led to a satisfying prediction of the FA concentrations in the 24 sampled rooms. The second axis deals with the analysis of the chemical profiles of 60 residences. From a screening of the VOC; homogeneous classes of chemical profiles associated with the dwellings could be established. Assumptions on the potential sources of these compounds were formulated and examined on the basis of the bibliography, the descriptive questionnaires of the dwellings and the emissions of materials and products present in indoor environment.LILLE1-Bib. Electronique (590099901) / SudocSudocFranceF

Assessment of Uncertainty of Benzene Measurements by Radiello Diffusive Sampler

The uncertainty of benzene measurements obtained by the analysis of thermally desorbable Radiello diffusive samplers was evaluated according to the recent standard EN 14662-4 (2005). Considering the results of laboratory experiments, all the sources of uncertainty regarding the diffusive sampler method characteristics were accessed for the sampling times of 7 and 14 days. The major part of the uncertainty budget (> 79 %) was explained by the variation of the sampling rate due to the environmental factors (temperature and concentration level). For weekly sampling, the diffusive sampler method satisfies the data quality objectives of the European Directive to supply the indicative measurements as well as the reference measurement, since the expanded uncertainty is found lower than 25 %. Using a model-predicted sampling rate which depends on the concentration and temperature, the expanded uncertainty is significantly decreased. The Radiello sampler was found to give correct results for weekly sampling provided that the range of benzene concentrations remained between 0 and 10 µg.m-3, which is generally observed in ambient air monitoring. For 2-week sampling, the expanded uncertainty of measurements exceeds 30 %. However, this diffusive sampler can still be used to carry out an objective evaluation of benzene (minimum quality objective for the accuracy of 100 %). Therefore, the performance of this diffusive sampler method appears to be suitable for the benzene monitoring in ambiant air.JRC.H.4-Transport and air qualit

Formaldehyde emission behaviour of wood based panels: application of a passive sampling for measuring the influence of decorative papers

International audienc

Formaldehyde emission behaviour of wood based panels: application of a passive sampling for measuring the influence of decorative papers

International audienc

The Equivalence of Diffusive Samplers to Reference Methods for Monitoring O3, Benzene and NO2 in Ambient Air

A study of the equivalence to the reference methods of the Radiello samplers for ozone (O3) and benzene as well as the membrane-closed Palmes tube (MCPT) for nitrogen dioxide (NO2) is presented. These samplers benefit from new model equations capable of estimating their uptake rate. For O3, the aim here was to demonstrate the equivalence for the reference period of 8 hours and 120 µg m-³, the target value stated in the 3rd Daughter Directive. For benzene, the demonstration of equivalence to the annual limit value of 5 µg.m-3 as stated in the 2nd Daughter Directive was examined. In the case of NO2, the equivalence to the annual limit value as stated in the 1st Daughter Directive (40 µg m-³) was considered. Results show that the radial sampler for O3 fails to meet the Data Quality Objective (DQO) for continuous monitoring. However, with an expanded uncertainty of less than 30%, the O3 diffusive sampler fulfils the DQO for indicative measurements. For benzene, the Radiello sampler exposed for 7 days gave satisfying results showing the ability of the sampler to meet the DQO of the reference method. Nevertheless, the field tests should be complemented by measurements for a wider range of benzene concentrations. In the case of NO2, all the results of the laboratory and field experiments respected the requirements of the demonstration of equivalence. Overall, these findings thus show that the Radiello sampler and the MCPT are equivalent to the reference methods only for assessment of benzene and NO2 respectively.JRC.F.8-Sustainable Transpor

New SPME-based method for on-site measurement of gas-phase concentration of phthalates and alternatives at the surface of PVC floorings

Phthalates are part of the semi-volatile organic compounds. They are widely used as plasticizers in polyvinyl chloride (PVC) floorings and are ubiquitous indoor pollutants. Some of them are even classified as carcinogenic, mutagenic, reprotoxic (CMR), and as we spend more time indoors, it is necessary to develop methods to assess emission strength of indoor materials. One of the key parameters to measure this potential is the concentration at the source material surface (y0). To measure directly this parameter, an in-situ sampling method using solid-phase microextraction (SPME) into an emission cell was developed. The main challenge with this method is calibration. Firstly, based on the headspace analysis of seven floorings, four samples were identified as sources of diisobutyl phthalate (DiBP), dibutyl terephthalate (DBTP) and benzoate esters. Secondly, an atmosphere generation system using a flooring sample as source of compounds and coupled with an active sampling with Tenax tubes was developed to perform an external calibration of the SPME based-MOSEC cell method suitable for y0 measurement. Calibration curves were set up on a wide range of exposure doses extending up to 96 µg min/m3 for DiBP and 184 µg min/m3 for DBTP. Low detection limits, 0.46 µg/m3 for DiBP and 1.50 µg/m3 for DBTP were determined considering an extraction time of 15 min. The principal limitation in the sampling conditions was identified as the 288 h required to reach steady state in the emission cell before the extraction step. Finally, y0 measured at the surface of PVC floorings ranged from 2.2 to 5.5 µg/m3 for DiBP and from 6.1 to 13.5 µg/m3 for DBTP