Unmanned Aerial Air Quality measurements: the potential for industrial fire plumes characterization with onboard low-cost sensor measurements

International audienceDuring an industrial fire, potentially hazardous substances may be released outside the site by atmospheric transfer. In order to characterize their potential impact, it is essential to gather data as quickly and reliably as possible on the consequences of the event on the environment and on the population. However, recent events related to the Lubrizol 2019 factory fire in Rouen have highlighted the difficulty in certain circumstances of listing the composition of fumes and knowing the mechanisms that contributed to their emission. These shortcomings taint the numerical models used to prioritize the fallout zones and thus distort the assessment of the impact of the fire on the environment and the health of the populations. The DESIHR project (Drones en Essaims pour la Surveillance de Sites Industriels à Hauts Risques), winner of an French National Research Agency grant, aims to develop innovative tools and methods based on the use of a fleet of autonomous drones to characterize in real-life situations the substances present in a fire plume as well as their emission and propagation conditions. The definition of the control laws governing the behaviour of each drone must in this context be based on real-time air quality information from sensors onboard each mobile vector. In order to limit the mass and the energy cost, low-cost sensors are among others considered in the DESIHR project. The objective of the work presented here is to address the potential for industrial fire plumes characterization with onboard low-cost sensor measurements in complex environments. On the basis of experiments carried out before the start of the project, it will address issues ranging from the selection of pollutants monitored and subsequent sensors to the use of data by drones, through the definition of innovative protocols for qualifying measurement performance based on real air matrices

Study of micro-sensors involved in monitoring and diagnosis of the airborne bio-pollutants in closed spaces.

En passant près de 90% de son temps dans les espaces clos, l'Homme est exposé à des polluants particulaires de diverses natures d'origines exogène et endogène au bâtiment, pour lesquels aucune valeur guide n'est disponible. Parmi ces polluants figurent les particules biologiques et notamment les spores fongiques, particules vivantes les plus nombreuses et les plus diversifiées de l'air que nous respirons (Nolard, 1997). Ubiquitaire et délétère, la pollution particulaire fongique est mise en cause dans la survenue de nombreuses pathologies parmi lesquelles se trouvent les maladies immuno-allergiques. Dans le cadre de la surveillance de la qualité micro-biologique de l'air des espaces clos, cette thèse vise à fournir les premiers éléments de conception d'un outil individuel de diagnostic dédié à l'évaluation de l'exposition des occupants aux aérobiocontaminants allergéniques en s'intéressant plus particulièrement à la pollution fongique aéroportée. Cette recherche repose sur les expertises techniques et scientifiques du CSTB, de l'ESIEE et de l'Université Paris-Est en matière de détection fongique, de miniaturisation d'instruments de mesure via les micro technologies et de physique des aérosols. Se faisant, ces travaux cristallisent autour d'une architecture système reposant sur trois axes : la capture et sélection des particules selon leurs propriétés physico-chimiques de surface, la quantification de la masse des particules et l'identification de la nature des particules à l'aide d'une analyse chimique. Ces axes correspondent à autant de thématiques abordées au cours de ces travaux de thèse. Ainsi, la première a consisté à étudier l'adhérence des conidies aux surfaces afin de mieux cerner les déterminants de ce phénomène physique et évaluer les énergies mises en jeu. Les résultats subséquents ont permis, lors d'une deuxième phase de travail, de dimensionner une microbalance en silicium de type MEMS en replaçant les problématiques liées aux interactions particules-résonateurs au cœur du débat. Par ce biais, l'enjeu a été de lever certains verrous scientifiques constatés dans la littérature, telles des sensibilités non-uniformes sur toute la surface des dispositifs de mesure ou encore des réponses en fréquence non linéaires avec la masse déposée. Une telle approche a en outre permis d'évaluer les performances attendues pour de tels capteurs. Enfin, le dernier aspect de cette recherche a porté sur l'identification des particules aéroportées biologiques par voie chimique en combinant pyrolyse des entités biologiques d'intérêt, chromatographie en phase gazeuse et spectroscopie de masse (Py-CPG/MS). A cette occasion, un travail collaboratif engagé avec le Réseau National de Surveillance Aérobiologique a permis d'éprouver la solution technologique et la méthodologie employées puisqu'une seconde catégorie de particules modèles a alors été considérée : les pollens. L'analyse des composés organiques volatiles issus de l'analyse Py-CPG/MS des micromycètes et des pollens a permis de démontrer l'existence d'une signature chimique spécifique de l'origine biologique des particules. Suite à cela, il a été possible d'établir diverses listes de traceurs chimiques caractéristiques des phyla voire des espèces des différents contaminants étudiés. La pertinence de ces marqueurs a alors été éprouvée lors d'un essai in situNowadays people pass 90% of their time in closed spaces, and in consequence are exposed to indoor and outdoor particulate matter for which no reference value is available. These pollutants include biological particles and in particular fungal spores, the most numerous living particles and most diverse on the air we breathe (Nolard, 1997). Ubiquitous and harmful, fungal particulate pollution is implicated in the occurrence of many diseases including immuno-allergic diseases. In the context of the monitoring of the microbiological quality of air in indoor spaces, this thesis aims to provide first design elements of an individual diagnostic device dedicated to the exposure assessment of allergenic bio-contaminants focusing in particular on airborne fungal pollution. This research relies on the technical and scientific expertise of CSTB, ESIEE Paris and Université Paris-Est for fungal detection, miniaturization of measurement instrumentation and aerosol physics. Thus, this work is built around a system architecture based on three main elements: the capture and selection of particles according to their surface physical and chemical properties, the particles mass quantification and the identification of the nature of the particle using chemical analysis. These elements relate to many topics covered during the thesis work. In this way, the first topic consists in studying the adhesion of conidia to surfaces to better understand the determinants of this physical phenomenon and evaluate the energies involved. Subsequent results were used during a second stage of this work, to design a MEMS-type silicon microbalance considering the particle-resonator interaction. By this mean the issue was to solve some scientific challenges identified in the literature, such non-uniform sensitivity over the entire device surface or nonlinear frequency responses due to the added mass. Such an approach has also allowed evaluating the performance expected for such sensors. The last aspect of this research focused on the identification of biological airborne particles chemically combining pyrolysis of biological entities of interest, and gas chromatography and mass spectrometry (Py-GC/MS). On this occasion, a collaborative work engaged with the "Réseau National de Surveillance Aérobiologique" allowed to experience the technological solution and our methodology since another class of particles was considered: pollens. The analysis of volatile organic compounds obtained from Py-GC/MS characterization of micro-fungi and pollens demonstrated the existence of a specific chemical signature for each biological particle class. Thereafter, it was then possible to establish a variety of chemical markers lists for phyla and different species of the contaminants studied. The relevance of these markers has been further tested in an in-situ assa

Cairsens NO2: A Miniature Device Dedicated to the Indicative Measurement of Nitrogen Dioxide in Ambient Air

This paper reports the study of data quality of Cairsens NO2 environmental sensors. In order to evaluate sensors performances, the investigation was performed through: a prospective follow-up of short-term and long terms drifts, the evaluation of the effects of environmental conditions upon sensors measurements as well as the evaluation of the ozone-filter lifetime. In this purpose, a dedicated test bench has been developed to expose sensors to a fixed concentration of ozone while recording sensors response

Le potentiel des capteurs de qualité de l'air à bas coût sur les drones pour la caractérisation des panaches de feux industriels : choix des capteurs et outils innovants pour caractériser les performances de mesure

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Impact of different particle sources on the measurement of PM by low-cost sensors

International audienc

Impact of different particle sources the measurement of PM by low-cost sensors

International audienceDuring the last years, as a member of the French National Reference Laboratory for monitoring air quality (LCSQA), Ineris has been developing and using "a PM enhanced generation system for inter-laboratory comparisons of automatic PM analysers". This facility is based on particle generation by nebulising a mixture of ammonium sulphate and ammonium nitrate diluted in distilled water using a TSI model 3076 nebuliser. However, this method of generation only produces particles with a distribution size limited to 2.5µm, excluding the possibility of evaluating the performance of measurements for the sole larger particles, such as those contributing to the PM10 mass.The objective of the work presented was to evaluate the possibility of generating particles with a larger granulometry and their impact on the measurement carry out by PM low-cost sensor in comparison with an automatic measurement system. This work has been divided in two parts:We first studied the impact of the type of generation method used on the mass concentration and granulometry of the particles generated using the same saline solution. We have shown that whatever the nebuliser used, i.e. whatever the limit imposed by the cut-off diameter, the generation from saline solution produces particles with a size centred around 600nm and corresponding mainly to PM2.5. In a second step, we studied the possibility to generate large particles by using a dispersion of Arizona dust in water. Indeed, even if the particle size distribution remains centred around 600nm, the presence of larger diameter particles has a major impact on the PM10 fraction. The simultaneous use of both methods showed the possibility of adding an independent contribution for the PM10 fraction. Finally, we propose to discuss the impact of the two generation methods, independently and combined, on the measurements of a PM low-cost sensor in comparison to an automatic measurement system commonly used for the air quality monitoring

Design optimisation of silicon-based MEMS sensors dedicated to bioaerosols monitoring

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Développement d'un protocole d'évaluation en chambre atmosphérique de préleveurs de particules employés dans le cadre d'études toxicologiques : (1) détermination des conditions de génération

International audienceThere is a need to find new techniques for sampling atmospheric particles to carry out toxicological analyses (e.g. in vitro). Current techniques use unsuitable media (filters) for the analyses. A new approach would be to test new technologies used in the field of bioaerosols, with different sampling media (e.g. sampling directly in a liquid). Unfortunately, the collection efficiencies of these technologies remain poorly known. The present abstract is focused on the development of a protocol for the evaluation of such samplers in atmospheric chambers. The first generations tests (tests of different generation parameters, choice of instruments) are presented.Les dispositifs de prélèvement de particules atmosphériques actuels ne permettent pas d'effectuer de façon satisfaisante des analyses toxicologiques, en raison de l'utilisation d'un support (filtres) pouvant induire un impact sur la modification physico-chimique des particules ce qui est peu adapté pour les analyses toxicologiques (e.g. in vitro). C'est pourquoi un intérêt est porté sur de nouvelles technologies utilisées dans le domaine des bioaérosols permettant des prélèvements directement dans un milieu approprié pour exposer ultérieurement les cellules (e.g. prélèvement en milieu liquide) mais dont l'efficacité de collecte selon la taille des particules est inconnue. Le papier présenté ici s'intéresse au développement d'un protocole d'évaluation de tels préleveurs en chambre atmosphérique, pour lever ces inconnues. Les premiers essais de générations (tests de différents paramètres de génération, choix du matériel) y sont présentés. In fine, l'objectif est d'appréhender la méthode la plus adaptée permettant une collecte suffisante de particules pour une meilleure sensibilité et induisant l'impact le plus limité sur la modification physico-chimique des particules pour les analyses toxicologiques

Performances of low-cost optical PM sensors for indoor air quality monitoring in mobility situations by car around Paris

In many industrialized countries, people spend more than one hour a day in their vehicles where particulate matter (PM) could reach high concentrations [1]. Though such a situation has become a matter of public concern, the lack of concentration data makes the monitoring of these ambiances difficult to apprehend. In order to tackle this challenge, attention is redirected towards the low-cost sensing units. Indeed, besides some interesting features such as portability, fast-deployment and cost, these devices can help to remotely characterize and monitor the spatial and temporal patterns of pollution sources [2]. However, once deployed, sensors information may be unreliable if uncertainties or intrinsic sensors’ limitations are not taken into consideration [3]. In this study, the objective is to evaluate performances of low-cost optical PM sensors under running conditions near the Paris ring-road and motorways. An appropriate field test campaign was designed and carried out within an instrumental car equipped with a GPS tracker and, reference and equivalent PM-measurement methods. For PM10 and PM2.5 values, data comparisons were performed across different seasons and pollution contexts (urban and semi-urban). Such an approach allowed to consider the influence of the inside car conditions (temperature and relative humidity) and the one associated to the physico-chemical nature and morphology of the particles encountered in vehicle environment. If this first campaign demonstrated the feasibility of the deployment of micro-sensors for indoor air quality monitoring in mobility situations, the results lead to conclude that some technological improvements have to be implemented to ensure their validation in respect to reference methods