High Resolution Air Quality Modeling for Improved Characterization of Exposures and Health Risk to Traffic-Related Air Pollutants (TRAPs) in Urban Areas

Exposure to traffic-related air pollutants in health studies is often obtained from air quality models at a relatively coarse spatial resolution that is unable to capture concentration hotspots near roadways thus has the potential to underestimate the risk. The goal of this work is to improve the characterization of exposure and health risk to traffic-related air pollutants. The hypothesis is that dispersion models can reduce the error for large-scale exposure and risk assessment because of the capability for fine-resolution modeling. This overall hypothesis was verified by the following 3 studies. The first study describes the development of a modeling framework that combined space-time kriging and Gaussian dispersion to inform exposure estimates for traffic-related air pollutants with a high spatial resolution. This framework reduces CPU-time by 88-fold by reducing the required meteorological data, while retaining the accuracy of exposure estimates. With this work, air quality models can be used to achieve fine-resolution modeling. The second study compared a series of six different hourly-based exposure metrics including ambient background concentration from space-time ordinary kriging (STOK), ambient on-road concentration from research line source dispersion model (R-LINE), a hybrid concentration combining STOK and R-LINE, and their associated indoor concentrations from an indoor infiltration mass balance model. Using a hybrid-based indoor concentration as the standard, outdoor STOK metrics yielded large error at both population (67% to 93%) and individual level (average bias between -10% to 95%). The results of the study will help future epidemiology studies to select appropriate exposure metric(s) and reduce potential bias in exposure characterization, or even address exposure misclassification. The third study refines the hybrid approach further to model concentrations at a Census block level (~105,000 Census blocks) using a chemical transport air quality model, Community Multiscale Air Quality (CMAQ) model at a 36 km × 36 km grid resolution. The resultant concentration fields were than used to estimate on-road PM2.5-related mortality. The results show that the hybrid modeling approach estimated 24% more on-road PM2.5-related mortality than CMAQ. This highlight the importance to characterize near-road primary PM2.5 at fine spatial scales, and suggest the potential for previous studies to have underpredicted the on-road PM2.5 related mortality estimates.Doctor of Philosoph

L’aérobiologie du pollen de bouleau (Betula spp.) : synergie avec les facteurs environnementaux et impacts sur les maladies respiratoires

Paul Comtois, le directeur initial n'est pas membre du jury en raison de maladie (à long terme). Il n'a pas pu être membre du jury et remplacé par François Courchesne.Plusieurs études publiées à travers le monde ont montré une association entre les enjeux de santé liés aux maladies respiratoires, et les facteurs environnementaux suivants : aéroallergènes, pollution et conditions météorologiques. Cependant, beaucoup moins d'attention a été attribuée à l'impact combiné ou la synergie entre ces différentes familles de co-stresseurs. Ainsi, la notion de synergie entre les facteurs environnementaux et le pollen aéroporté représente le fil conducteur sous-jacent à cette thèse. Par ailleurs, des simulations numériques du pollen allergénique aéroporté (Betula spp.) sont nécessaires pour protéger et informer les citoyens des risques à la santé respiratoire mais aussi pour comprendre dans un contexte régional (à l’aide de cartographie), la variabilité spatio-temporelle à la fois des facteurs environnementaux et celle du pollen. Le système de simulation développé dans le cadre de cette thèse permet l'analyse combinée du transport et de la dispersion à moyenne et longue distance (TDMLD) du pollen anémophile et des polluants atmosphériques. Soumis à de multiples stress environnementaux durant son transport dans l’atmosphère, le grain de pollen peut subir une augmentation des fractures de son enveloppe externe (exine) conduisant à une libération de granules intracytoplasmiques ayant des propriétés allergisantes et une modification des allergènes ayant davantage d’impact sur les patients atopiques. Selon les recherches scientifiques, si ces protéines allergéniques présentes dans les grains de pollen sont inhalées, elles entraînent une attaque d’asthme chez des sujets susceptibles. Bien que la thèse discute d’un grand nombre d’aspects reliés à l’aérobiologie, elle ne permet pas encore de modéliser complètement toutes les facettes du problème mais ouvre la porte à plusieurs avenues de recherche multidisciplinaire. Cinq grandes questions de recherche ou défis méthodologiques sont abordées dans cette thèse : 1. Étant donné la rareté ou l’absence de mesures phénologiques, comment construire un module de phénologie qui sert d’intrant à un modèle d’émission pollinique pour le pollen de Betula (Chapitre 3) ? 2. Comment simuler et intégrer les émissions polliniques et reproduire adéquatement la dispersion du pollen aéroporté dans un modèle couplé météorologie/qualité de l’air déjà existant au Canada tenant compte du fait que ce modèle n’est pas conçu au départ pour simuler le pollen aéroporté (Chapitre 4) ? 3. Quelle est l’origine du pollen de Betula affectant la région de Montréal et quelle est la meilleure façon d’établir sa provenance, tenant compte du fait que les méthodes traditionnelles (rétro-trajectoires, méthode inverses, modèles bi-dimensionnels, etc.) présentent des difficultés qui leur sont propres (Chapitre 4) ? 4. Quels sont les liens synergiques entre l’exposition au pollen allergénique, la pollution et les conditions météorologiques et quels impacts se manifestent sur la santé respiratoire des patients atopiques compte tenu de la présence de facteurs de confusion (i.e. météorologiques, géographiques, socio-économiques, etc.) dans l’analyse des données de pollen de Betula en relation avec les maladies respiratoires à Montréal et au Québec (Chapitres 5 et 6) ? 5. Quelle est la variabilité spatio-temporelle des maladies respiratoires au Québec en relation avec les facteurs de l’environnement atmosphérique (Chapitre 6) ?Several studies published around the world have shown an association between health issues related to respiratory diseases and the following environmental factors: aeroallergens, air pollution and weather conditions. However, much less attention has been attributed to the combined impact or synergy between these different families of co-stressors. Thus, the notion of synergy between environmental factors and airborne pollen represents the main motivation underlying this thesis. Furthermore, numerical simulations of one of the most allergenic pollen (Betula spp.) are necessary to protect and inform citizens of the risks to respiratory health, but also to understand in a regional context (using mapping) the spatial variability of both environmental factors and airborne pollen. In this thesis, the developed simulation system allows the combined analysis of medium and long-distance transport and dispersion (TDMLD) of both anemophilic pollen and atmospheric pollutants. Subjected to multiple environmental stresses the pollen grain may undergo an increase in the fractures of its external envelope (exine) which can lead to a release of allergenic intracytoplasmic granules and a modification of the allergens exacerbating impacts on atopic patients. According to several researchers, these allergenic proteins present within pollen grains when inhaled cause attack of asthma in susceptible humans. Although the thesis discusses many aspects related to aerobiology, it does not yet allow to completely model all the facets of the problem. However, it opens the door to several avenues of multidisciplinary research. Five major research questions or methodological challenges are addressed in this thesis : 1. Given the scarcity or absence of phenological observations, how do we construct a phenology module that is suitable as an input to a pollen emission model for Betula pollen simulation (Chapter 3) ? 2. How to simulate and integrate pollen emissions and adequately reproduce airborne pollen dispersion in an existing coupled meteorology / air quality model developed in Canada, recognizing that this model is not originally designed to simulate airborne pollen (Chapter 4) ? 3. What is the origin of the Betula pollen affecting the Montreal area and what is the best way to establish its provenance, considering that traditional methods (back-trajectories, inverse methods, two-dimensional models, etc.) present their own difficulties (Chapter 4) ? 4. What are the synergistic links between exposure to allergenic pollen, pollution and weather conditions and what impacts are apparent on the respiratory health of atopic patients given the presence of confounding factors (i.e. meteorological, geographical, socio-economic, etc.) in the analysis of Betula pollen data in relation to respiratory diseases in Montreal and the province of Quebec (Chapters 5 and 6)? 5. What is the spatio-temporal variability of respiratory diseases in Quebec in relation to factors of the atmospheric environment (Chapter 6)

Relationship between synoptic circulations and the spatial distributions of rainfall in Zimbabwe

This study examines how the atmospheric circulation patterns in Africa south of the equator govern the spatial distribution of precipitation in Zimbabwe. The moisture circulation patterns are designated by an ample set of eight classified circulation types (CTs). Here it is shown that all wet CTs over Zimbabwe features enhanced cyclonic/convective activity in the southwest Indian Ocean. Therefore, enhanced moisture availability in the southwest Indian Ocean is necessary for rainfall formation in parts of Zimbabwe. The wettest CT in Zimbabwe is characterized by a ridging South Atlantic Ocean high-pressure, south of South Africa, driving an abundance of southeast moisture fluxes, from the southwest Indian Ocean into Zimbabwe. Due to the proximity of Zimbabwe to the Agulhas and Mozambique warm current, the activity of the ridging South Atlantic Ocean anticyclone is a dominant synoptic feature that favors above-average rainfall in Zimbabwe. Also, coupled with a weaker state of the Mascarene high, it is shown that a ridging South Atlantic Ocean high-pressure, south of South Africa, can be favorable for the southwest movement of tropical cyclones into the eastern coastal landmasses resulting in above-average rainfall in Zimbabwe. The driest CT is characterized by the northward track of the Southern Hemisphere mid-latitude cyclones leading to enhanced westerly fluxes in the southwest Indian Ocean, limiting moist southeast winds into Zimbabwe

Natural or anthropogenic variability? A long-term pattern of the zooplankton communities in an ever-changing transitional ecosystem

The Venice Lagoon is an important site belonging to the Italian Long-Term Ecological Research Network (LTER). Alongside with the increasing trend of water temperature and the relevant morphological changes, in recent years, the resident zooplankton populations have also continued to cope with the colonization by alien species, particularly the strong competitor Mnemiopsis leidyi. In this work, we compared the dynamics of the lagoon zooplankton over a period of 20 years. The physical and biological signals are analyzed and compared to evaluate the hypothesis that a slow shift in the environmental balance of the site, such as temperature increase, sea level rise (hereafter called “marinization”), and competition between species, is contributing to trigger a drift in the internal equilibrium of the resident core zooplankton. Though the copepod community does not seem to have changed its state, some important modifications of structure and assembly mechanisms have already been observed. The extension of the marine influence within the lagoon has compressed the spatial gradients of the habitat and created a greater segregation of the niches available to some typically estuarine taxa and broadened and strengthened the interactions between marine species