The oxidation of a range of Volatile Organic Compounds (VOCs) has been studied, from small alkenes (e.g. ethene C2) to larger sesquiterpene species (e.g. β-caryophyllene C15). The gas-phase reactions of these VOCs, largely emitted from biogenic sources, can form oxidation products with high mass and low volatility to contribute to aerosol formation, namely for monoterpene and sesquiterpene species. These organic aerosols formed from chemical reactions in the atmosphere are secondary organic aerosols (SOA). Aerosols can have a profound impact on both climate and health issues at regional and global scales. Processes that govern these gas-to-particle phase reactions are still not fully understood. This thesis presents detailed gas-phase composition data from the various VOCs examined, and tries to highlight important gas-phase species involved in the processes for SOA formation in the atmosphere. The gas-phase composition was measured in real-time utilising the University of Leicester Chemical Ionisation Reaction-Time of Flight-Mass Spectrometer (CIR-ToF-MS). Experiments were conducted under two different environments, “dark” ozonolysis experiments were studied at the EUropean PHOtoREactor (EUPHORE) atmospheric simulation chamber (Valencia, Spain) whilst “light” photooxidation experiments were conducted at the Manchester Aerosol Chamber (MAC) facility (Manchester, UK). The ozonolysis experiments focused around small alkene species (ethene, isobutene, and trans-2-butene), isoprene and monoterpenes (myrcene, α-pinene and limonene) in the absence of NOx and investigated with and without radical scavengers in order to suppress side reactions. Under dry conditions the primary oxidation products for smaller alkene ozonolysis averaged yields for formaldehyde (HCHO) as 1.56 ± 0.09, 1.21 ± 0.03 and 0.15 ± 0.01 for ethene, isobutene and trans-2-butene respectively. Other major gas phase product yields were recorded. Under wet conditions HCHO yields increased dramatically for ethene ozonolysis, to 3.09 ± 0.12 and 1.94 ± 0.31 for isobutene, but no substantial difference was observed for trans-2-butene with an average yield of 0.19 ± 0.04. Observations on gas-phase composition varied little based on the latter and model comparisons were made using the Master Chemical Mechanism (MCMv3.1). Photolysis experiments were conducted for isoprene, monoterpenes (limonene, α-pinene and myrcene) and a sesquiterpene, β-caryophyllene. This led to a direct comparison of composition and yields were obtained for certain oxygenated VOCs (oVOCs). The major gas phase products of isoprene ozonolysis, methacrolein (MACR) recorded average yields of 0.24 ± 0.16 and methyl-vinyl ketone (MVK) at 0.15 ± 0.01 for dry conditions, whilst yields of 0.36 ± 0.04 and 0.17 ± 0.02 were observed for wet conditions respectively. Similar yields were observed for photolysis conditions. The highest average yields in the gas phase for all monoterpene species were the primary aldehyde species formed (e.g. pinonaldehyde for α-pinene), ranging averaged yields from 0.115 to 0.583 for ozonolysis reactions and 0.119 to 0.270 under photolysis conditions. Where applicable, SOA yields were determined using a Differential Mobility Particle Sizer (DMPS) and composition of the particle phase made off-line using Liquid chromatography-ion trap mass spectrometry (LC-MSn). A unique method of organic seed formation was also constructed for photolysis experiments for isoprene and limonene using β-caryophyllene as a precursor for the organic seed. Finally mesocosm experiments of direct emissions from tree species Ficus cyathistipula, Ficus benjamina and Caryota millis (to simulate tropical Asian conditions) and Betula Pendula (to encompass European environments). The tropical monoterpene producing species formed SOA, whereas the European isoprene dominant species did not. Implications of this are further discussed along with the difference observed in gas-phase composition and yields of oxidation products produced from all experiments. An Am241 source and a newly developed hollow cathode source was utilised in both campaigns so instrumental sensitivity, in particular for lower mass species is also discussed. Evidence from the experiments shows that SOA formation is only observed from monoterpene and sesquiterpene compounds. Here isoprene did not form any substantial SOA and we argue it can inhibit SOA formation. Important gas phase species for SOA contribution were those of C10 or higher, in particular the primary aldehyde oxidation products of monoterpenes that were observed in both gas and particulate phase.

L'étude du comportement dynamique des substances actives pendant l'épandage de produits insecticides ménagers commerciaux dans les atmosphères intérieures nécessite le développement et l'adaptation de procédures analytiques de mesure en ligne ayant une résolution temporelle élevée. Un HS-PTR-MS et un HR-ToF-AMS ont par conséquent été utilisés pour mesurer les contaminants à la fois en phase gazeuse et particulaire. Les substances actives ciblées par cette étude appartiennent à la famille des pyréthrinoïdes, présentes dans différentes formulations commerciales du type diffuseurs électriques et sprays aérosols, qui ont été appliqués dans une pièce d'étude simulant une atmosphère réelle dans la maison expérimentale MARIA du Centre Scientifique et Technique du Bâtiment. Les résultats de ces mesures montrent des pics de concentration compris entre 1,5 et 8,5 µg.m-3, après 8 heures de branchement des diffuseurs électriques. Les pics de concentration des substances actives après l'application des sprays peuvent atteindre plusieurs dizaines de µg.m-3. La ventilation et la sédimentation des aérosols apparaissent comme des mécanismes majeurs d'élimination des polluants du compartiment air. Par ailleurs, une distribution importante des substances actives avec les surfaces de la pièce (murs, sol, plafond, particules en suspension et poussières) est observée. L'évaluation de l'exposition par inhalation aux produits insecticides étudiés montre qu'il n'existe a priori pas de risque pour la santé. Néanmoins, une évaluation intégrée, prenant en compte toutes les voies d'exposition est nécessaire avant de conclure à une absence de risque sanitaire. / The study of the dynamic behaviour of the active substances during the application of commercial household insecticide products in indoor atmospheres requires the development of the adaptation of on-line analytical procedures with high time resolution. A HS-PTR-MS and a HR-ToF-AMS have therefore been used to measure contaminants both in the gaseous and particulate phase. The active substances targeted by this study belong to the pyrethroids, which are present in different commercial formulations like electric vaporizers and sprays that were applied in a full-scale test room simulating a real atmosphere in the experimental house MARIA of the French scientific and technical centre for building. The results of these measurements show that peak concentrations during a 8h-emission of electric vaporizers range from 1,5 et 8,5 µg.m-3. The peak concentrations of active substances during spraying can reach several dozens of µg.m-3. Ventilation and deposition of aerosols are major elimination mechanisms of pollutants from the air compartment. Moreover, an important distribution of active substances with the surfaces of the room (walls, floor, ceiling, suspended particles and dust) is observed. The evaluation of inhalation exposure to the studied insecticide products show that adverse effects are not likely to occur. Nevertheless, to conclude that these products are safe, it is necessary to perform an integrated evaluation, taking into account all exposure routes.

L’appréciation par le consommateur d’un produit alimentaire comme le chocolat est en grande partie due à sa composante aromatique. La perception de cette composante est étroitement liée à la libération des composés d’arômes lors de la consommation du produit. Une étude sensorielle systématiquement menée par la société Valrhona dans une démarche de qualification de ses chocolats noirs de pures origines, fabriqués selon un procédé standard à partir de lots de cacao différents, permet de classer ces chocolats, selon leur profil, en quatre grands pôles sensoriels. Le travail entrepris avait pour but la compréhension de l’origine de cette classification sensorielle par la mise en œuvre de techniques de caractérisation des molécules volatiles responsables de l’arôme des chocolats.Dans un premier temps, l’empreinte globale en composés volatils d’un lot de 206 chocolats représentatifs des quatre pôles sensoriels a été obtenue via une méthode d’analyse couplant un headspace dynamique à la spectrométrie de masse en injection directe, utilisant l’ionisation par transfert de protons (PTR-ToF-MS). Des analyses multivariées des données, et notamment une analyse discriminante de type PLS-DA, ont permis d’élaborer un modèle de prédiction de la classification sensorielle des chocolats basé sur leur composition en molécules volatiles. Différentes méthodes de sélection de variables ont permis de souligner l’existence de composés volatils particuliers capables de discriminer les quatre pôles sensoriels de chocolats.Le potentiel aromatique de 12 chocolats parmi les 206 (trois de chaque pôle) a ensuite été déterminé suite à l’extraction des arômes par une méthode de distillation sous vide dans une analyse par chromatographie en phase gazeuse couplée, d’une part, à l’olfactométrie (GC-O) basée sur la fréquence de détection obtenue par 12 juges, et d’autre part, à un spectromètre de masse (GC-MS) pour l’identification des composés odorants. Ainsi, des composés d’arômes permettant de discriminer les différents pôles sensoriels ont pu être caractérisés au moyen d’une analyse factorielle des correspondances.Enfin, l’analyse « nosespace » d’un jury de 12 personnes dégustant 8 chocolats (deux de chaque pôle parmi les 12 précédents) a été réalisé en PTR-MS. Cette étude, couplée à une analyse sensorielle temporelle (Dominance Temporelle des Sensations, DTS), a permis d’obtenir des données temporelles instrumentales et sensorielles de manière simultanée. L’analyse DTS révèle dans une analyse en composantes principales (ACP) une bonne discrimination des pôles sensoriels, avec des descripteurs dominants similaires dans les pôles 1 et 4, d’une part, et dans les pôles 2 et 3, d’autre part. L’analyse nosespace a permis le suivi de la libération en temps réel de 26 composés d’arômes. La relation entre les deux jeux de données (instrumentales et sensorielles) a été étudiée au moyen de l’indice AWD (Abundance While Dominance) qui représente l’abondance de chaque ion pendant qu’une sensation est dominante. Des analyses factorielles des correspondances menées sur les AWD ont permis pour chaque échantillon de déceler des relations entre composés d’arômes libérés et sensations dominantes. / Consumers’ appreciation of chocolate is mostly due to its aromatic composition. Perception of this component is clearly linked to the release of aroma compounds during chocolate consumption. A systematic sensory evaluation is conducted by the Valrhona Company in order to qualify their pure origin dark chocolates manufactured according to a standard process from differing cocoa batches. The obtained sensory profiles allow classifying the chocolates into four sensory categories, named poles. The objective of the present work was to understand the molecular origin of this sensory classification by using techniques aimed at characterizing volatile organic compounds (VOC) responsible for chocolate flavour.Firstly, global VOC profiles of a set of 206 chocolate samples classified in the four sensory poles were analysed by a direct injection mass spectrometry method using proton transfer reaction as ionisation process (PTR-ToF-MS). A supervised multivariate data analysis based on discriminant analysis of the PLS-DA type allowed the construction of a classification model that showed excellent prediction capability based on VOC composition of the chocolates. Variable selection using dedicated methods pinpointed some volatile compounds important for the chocolates sensory discrimination.Then, the aroma potential of 12 chocolate samples (chosen among the 206 ones with three samples representative of each pole) was investigated on aroma extracts obtained by distillation under vacuum. Gas chromatography coupled to olfactometry (GC-O) and to mass spectrometry (GC-MS) was used to detect and identify the odorous compounds. GC-O data were obtained by 12 assessors using the detection frequency method. Aroma compounds allowing the discrimination of the sensory poles were determined thanks to a correspondence analysis.Finally, a nosespace analysis conducted by 12 assessors on 8 chocolates (two in each pole among the preceding 12) was realised using PTR-MS. This analysis was conducted simultaneously with a temporal sensory analysis (Temporal Dominance of Sensations, TDS), allowing temporal instrumental and sensorial data to be obtained. A principal component analysis (PCA) conducted on the TDS data revealed a good discrimination of the sensory poles, with similar dominant attributes in poles 1 and 4, on the one hand, and in poles 2 and 3, on the other hand. The nosespace data displayed real time release curves of 26 aroma compounds. The relationships between instrumental and sensory data were investigated thanks to the AWD (Abundance While Dominance) index that measures the abundance (area under the curve) of each ion during the dominance of a given sensation. Correspondence analyses of the AWD indices conducted for each chocolate sample allowed to define some relationships between dominant sensations and some released aroma compounds.

Du fait de la miniaturisation des composants semi-conducteurs, il est devenu de plus en plus important de réduire les niveaux de contamination. Les salles blanches sont indispensables pour assurer un environnement adéquat pour l'élaboration des composants microélectroniques. Toutefois, jusqu'à présent aucune technologie ne permet le contrôle de la contamination organique volatile, et même dans tels environnements contrôlés, la contamination des surfaces de wafers a souvent lieu. Une nouvelle approche expérimentale a été développée dans notre laboratoire afin de suivre les processus d'adsorption et de désorption des contaminants organiques volatils et semi-volatils à la surface des wafers. Ce dispositif est constitué de trois composants principaux : un générateur des composés en phase gaz, un tube à écoulement et le spectromètre de masse par transfert de proton comme outil analytique de mesure de la composition de la phase gazeuse. Les comportements d'adsorption de cinq composés organiques volatils parmi les plus abondants dans les environnements des salles blanches (l'isopropanol, l'acétone, le xylène, l'acétate d'éthyle et le propylène glycol méthyl éther acétate) et trois semi-volatils (diéthylphtalate, tri-(2-chloroéthyl)-phosphate et le tri- (2-cloropropyl)-phosphate) ont été étudiés. Les paramètres cinétiques des processus d'adsorption ont été déterminés. Les corrélations entre leurs concentrations en phase gazeuse et leurs densités à la surface des wafers ont été établies. En comparant les comportements d'adsorption de tous les composés étudiés, il a été démontré que la constante de désorption kdes est le facteur le plus influent sur les équilibres d'adsorption. / As semiconductor devices become smaller, it is increasingly important to reduce the degree of organic contamination in the areas where such devices are produced. It has been shown that cleanrooms are indispensable to provide a suitable environment for processing semiconductor devices. However, at present time there is no technology for controlling the contamination with volatile organic compounds (VOC), and even in such an environment, the wafers are exposed to VOC. A new experimental approach has been developed in our laboratory in order to follow the adsorption and desorption processes of volatile and semi volatiles organic compounds on silicon wafer surfaces. This unique setup is based on three principal components: a stable gas-phase generator, a flow tube reactor, and a proton-transfer-reaction–mass spectrometry (PTR-MS) analytical device to monitor the VOC. The adsorption behavior of five the most abundant VOCs in the cleanroom environment (isopropanol, acetone, xylene, ethyl acetate and propylene glycol methyl ether acetate) and three semi volatile organic compounds (diethylphtalate, tri-(2-chloroethyl)-phosphate and tri-(2-cloropropyl)-phosphate) on silicon wafer surface was studied. The kinetic parameters were determined and correlations between the gas phase concentrations and the surface densities of the organic contaminants were established. By comparing the adsorption properties of the studied compounds, it has been demonstrated that time dependant changes in the surface concentration of the organic species are governed by desorption constants, kdes. Moreover, kdes was found to be dependent on the molecular weight of the studied organics.

Les choix et préférences des consommateurs pour les aliments sont largement conditionnés par leurs propriétés sensorielles, et notamment par les perceptions aromatiques dans le cas des boissons alcoolisées. Un des enjeux des industriels du secteur pour contrôler et développer les ventes des produits est de mieux comprendre les déterminants de la qualité sensorielle de ces produits. Les travaux réalisés dans le cadre de ce projet de thèse concernent les cognacs et visent à appréhender les liens entre la composition des produits, les étapes du processus d’élaboration, dont la phase de vieillissement, et leurs caractéristiques sensorielles finales. L’objectif est notamment de comprendre l’impact des constituants de la matrice des cognacs sur la libération et la perception des composés d’arôme. Pour répondre à cet objectif, une stratégie fondée sur des approches sensorielle et physicochimique a été mise en œuvre. Les travaux réalisés en évaluation sensorielle ont permis de montrer l’absence d’impact des constituants non-volatils et de réaffirmer l’importance des composés d’arôme dans la perception des différences sensorielles entre les cognacs. Le suivi des libérations de composés d’arôme par PTR-MS au cours de la consommation des cognacs a été possible par la mise au point de conditions opératoires compatibles avec la teneur élevée en éthanol des produits. Ces travaux ont montré que les composés d’arôme clés pour la perception des cognacs étaient libérés en plus grandes quantités dans les cognacs les plus âgés. En revanche, aucune différence entre les produits n’a été constatée au niveau de la temporalité de ces libérations. L’application des approches statistiques prédictives a finalement permis de montrer qu’il est possible de prédire les propriétés sensorielles des cognacs à partir de certaines de leurs caractéristiques physicochimiques, et que les corrélations établies entre les variables physicochimiques et sensorielles pouvaient être expliquées qualitativement grâce aux connaissances existantes dans la littérature et à celles des experts, notamment concernant leur processus d’élaboration. / Consumer’s choices and preferences for foods are widely influenced by their sensory properties, and especially by aromatic perceptions in the case of alcoholic beverages. One of the challenges of wine and spirit industries for controlling and developing product sales is to gain insights on the determinants of the sensory quality of their products. The work carried out during this PhD project concerns cognacs and aim to apprehend the links between product composition, the stages in their elaboration process, including maturation, and their final sensory properties. An important objective is to understand the impact of cognac matrix components on aroma compounds release and perception. To fulfill this objective, a strategy based on the use of physicochemical and sensory approaches was set up. Sensory evaluation enabled to highlight the absence of impact of non-volatile components and to reaffirm the essential effect of aroma compounds for the perception of sensory differences between cognacs. The monitoring of the release of aroma compounds by PTR-MS during cognac consumption has been possible by the setting up of operating conditions allowing the analysis of high ethanol-containing beverages. These works have shown that key aroma compounds for cognac perception were released in higher amounts in the oldest cognacs. However, no difference was observed concerning their temporality of release. The development of statistical approaches finally showed that it was possible to predict the sensory properties of cognacs from their physicochemical characteristics. Correlations between physicochemical and sensory variables could be qualitatively explained in reference to the knowledge on the elaboration process of cognac in the literature and held by experts.

There are few published direct measurements of the atmosphere-surface exchange of volatile organic compounds (VOCs), particularly for biogenic VOCs (BVOCs). Global modelling of atmospheric chemistry and transport of BVOCs has large uncertainties due to the very small number of measurements in tropical regions, which are responsible for half the global BVOC emissions. This thesis presents direct measurements of concentrations and ecosystem fluxes of BVOCs in different regions (Tropics, Mediterranean) using the approach of virtual disjunct eddy covariance (vDEC) combined with proton transfer reaction mass spectrometry (PTR-MS) – a real-time BVOC sensor. The field measurements also included methodological developments of the vDEC/PTR-MS approach, which will be of value to the wider flux measurement community. A novel approach to determining the lag time between the vertical wind measurement and the air concentration measurement has been developed that will greatly reduce the uncertainty in the derived flux measurements. In the laboratory, the selectivity of PTR-MS was investigated by designing an alternating drift-voltage mode (AD-PTR-MS) to discriminate between structural isomers detected at the same m/z channel, with monoterpenes used as model compounds. The results of the measurements, particularly from the rainforest and oil palm plantations in Borneo, are novel and therefore provide important experimental constraints on models of atmospheric emissions, chemistry and transport. For example, although parameters which work reasonably well can be derived for model algorithms for the emission of isoprene from the rainforest, their performance over oil palms was less good, because of circadian controls of emissions from oil palms. However, the larger problem is the measured basal emission rates (BERs) which are significantly smaller than those used by default in the global MEGAN model. Another novel finding was the high deposition velocities of MVK and MACR (isoprene first order oxidation products) which at the oil palm plantation commonly exceeded 1 cm s-1; this result has implications for atmospheric modelling. The successful field results relied on significant developments in software for data acquisition and processing, and operational optimisation of the PTR-MS instruments in the extreme humidity encountered during the fieldwork in Borneo.

La perception de la flaveur des aliments dépend de la perception de plusieurs composés en mélange dans des proportions équilibrées. Interactions perceptives entre différents odorants ainsi que la libération dynamique des odorants par la matrice alimentaire sont les principaux facteurs qui influencent la perception globale. L’objectif de cette thèse de doctorat était d’étudier la perception du mélange d’odorants qui constituent l’arôme du fromage à pâte pressée, en prenant en compte les interactions perceptives et la dynamique de libération des composés par la matrice. Une stratégie, comprenant une caractérisation complète des odorants des fromages, suivie d’une recombinaison qualitative et d’une étude détaillée des rôles respectifs des composés clés, et finalement la prise en compte de la dynamique de libération par incorporation des composés dans une matrice fromagère, a été appliquée. Des caractérisations approfondies sensorielles et instrumentales nous ont permis de mettre en évidence des relations entre la perception sensorielle et la composition des composés volatils et proposer des hypothèses. La recombinaison des différents composés a été testée afin d’étudier le rôle de chacun en mélange. Aidés par des apprentis aromaticiens durant la phase des recombinaisons nous avons pu observer particulièrement que 12 composés étaient très importants pour l’odeur du fromage. Par la suite nous avons étudié des interactions entre odeurs en appliquant des techniques de stimulation odorante en phase gazeuse, puis la dynamique de libération des composés en incorporant l’arôme dans une matrice fromagère par des techniques permettant de mesurer la quantité libérée en fonction du temps. / Perception of the aroma of food products depends both the chemical composition of food and human neurophysiology. The perception of food flavour, including cheese often relies on the perception of several aroma compounds in mixture in balanced proportions. Perceptual interactions among aroma compounds in mixtures and also the release of aroma compounds from the food product are the main factors that influence the global perceived aroma of food. Hence, the objective of this PhD study was to investigate the mixture of aroma compounds representing the aroma of semi-hard cheese by taking into account perceptual interactions among odorants and the dynamic release of the compounds by the cheese matrix. A strategy involving a complete characterisation of the cheeses followed by a recombination and investigation of the role of the key-aroma compounds and the dynamic release of the aroma compounds from the cheese matrix was taken into account. Comparison of the sensory and instrumental characteristics was made in order to highlight relationships between sensory perception of the aroma and the volatile composition of the cheeses and thus point out the molecular origins of the perceived cheese aroma. Recombination of selected aroma compounds was tested, in order to study the role of each aroma compound within the mixture. Especially 12 compounds seemed important for the semi-hard cheese aroma. To investigate the odour-odour interactions, different odour-stimulation tools were applied and dynamic release of aroma compounds was taken into account by incorporating the aroma compounds into a cheese matrix by different techniques allowing measuring the quantities released as function of time.

The diploma thesis is focused on the study of chemical reaction products in prebiotic atmospheres. The theoretical part deals with the main theories of composing the atmosphere of the early Earth, hypotheses of the origin of life and genetic code in the form of RNA, the atmosphere of the moon Titan and the basic characteristics of the gliding arc discharge, and the analytical techniques used in the diploma thesis. In the experimental part, study of products was carried out by experimental atmospheric simulations in a special stainless steel reactor in various mixtures of gases N2, CH4, CO2 and O2. The electrical discharge for atmospheric simulation was generated by an electrode configuration for the gliding arc discharge and glow discharge. Detection and identification of chemical reaction products was performed by Gas Chromatography with Mass Spectrometry (GC-MS) and Flame Ionization Detector (GC-FID), Testo 350 M/XL and Proton Transfer Reaction Mass Spectrometry (PTR-MS). A theoretical kinetic model was created to predict and confirm the detected products. During the experiments, the dependence of the product intensity on changes in the composition of the gaseous mixture and the applied value of the electric current was also observed.

This thesis describes the on-road analysis of criteria air pollutants (CAPs) and volatile organic compounds (VOCs) from a moving vehicle. CAPs and VOCs have numerous direct and indirect effects on the environment and public health and are generated from a variety of point and diffuse sources. The concentration of these pollutants can vary on the scale of metres and seconds due to variable emission rates of sources, meteorology, and the topography of an area. CAPs are conventionally measured on a spatial scale of tens of kilometres and one hour or longer time resolution, which limits the understanding of their impact and leaving many communities lacking information regarding their air quality. VOCs are not measured as frequently as CAPs, owing to the difficulty, challenges, and cost associated with sampling. The Mobile Mass Spectrometry Lab (MMSL) was developed to collect high geospatial (15 – 1,500 m) and temporal (1 – 10 s) resolution measurements of CAPs (O3, NOx, PM2.5), CO2, CH4, and VOCs. CAPs and greenhouse gases were monitored using standard analyzers, while VOCs were measured using a proton-transfer reaction time-of-flight mass spectrometer (PTR-MS). PTR-MS is a real-time, direct, in situ technique that can monitor VOCs in the ambient atmosphere without sample collection. The PTR-MS monitored up to mass-to-charge 330 with a sample integration time of 1 or 10 seconds and had detection limits into the low- to mid-ppt. PTR-MS is a soft ionization technique that is selective to all compounds with a proton affinity less than water, which excludes the atmospheric matrix and includes most VOCs. The measurements provided by the PTR-MS provided a rich dataset for which to develop workflow and processing methods alongside sampling strategies for the collection of high geospatial and temporal VOC data. The first on-road deployment of the MMSL was performed across the Regional District of Nanaimo and the Alberni-Clayoquot Regional District in British Columbia, Canada, from July iv 2018 – April 2019 to monitor the geospatial and temporal variation in the concentration of CAPs and VOCs. VOCs detected in the areas include hydrocarbons like toluene, C2-benzenes, and terpenes, organic acids like acetic acid, oxygenated compounds like acetone and acetaldehyde, and reduced sulfur compounds like methanethiol and dimethyl sulfide. While observed concentrations of VOCs were mostly below detection limits, concentration excursions upwards of 2,200 ppb for C2-benzenes (reported as ethylbenzene) for instance, were observed across the various communities and industries that comprise central Vancouver Island. VOCs like monoterpenes, were observed near the wood industries up to 229 ppb. Combustion related VOCs, like toluene and C2-benzenes, were often observed on major transportation corridors and was found to vary significantly between seasons, with winter measurements often exceeding those made in the summer. Reduced sulfur compounds, common components of nuisance odours, were measured around a few industries like waste management and wood industries. The second on-road deployment of the MMSL focused on the analysis of VOCs in the community around a wastewater treatment plant (WWTP) to identify the source of odours in the area. VOCs were also monitored in the odour control process of the WWTP to identify the VOCs being emitted, how much were emitted, and where potential deficiencies were in the process in a unique study. Median emission rates at the facility for methanethiol, dimethyl sulfide, and dimethyl disulfide were determined to be 100, 19, and 21 kg yr-1, respectively. VOC monitoring in the community encompassed the WWTP and the other major industries in the area, including agricultural land, a composting facility, and a marina. The highest measurements of odorous reduced sulfur compounds were observed around the WWTP, upwards of 36 ppb for methanethiol. Unsupervised multivariate analysis was performed to identify groups of VOCs present and their potential sources. Three groups were identified, one of which was related to reduced sulfur compounds. This group was observed around the WWTP, indicating that the WWTP was the likely source of malodours in the community. / Graduate