51 research outputs found

    Air Quality Research Using Remote Sensing

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    Air pollution is a worldwide environmental hazard that poses serious consequences not only for human health and the climate but also for agriculture, ecosystems, and cultural heritage, among other factors. According to the WHO, there are 8 million premature deaths every year as a result of exposure to ambient air pollution. In addition, more than 90% of the world’s population live in areas where the air quality is poor, exceeding the recommended limits. On the other hand, air pollution and the climate co-influence one another through complex physicochemical interactions in the atmosphere that alter the Earth’s energy balance and have implications for climate change and the air quality. It is important to measure specific atmospheric parameters and pollutant compound concentrations, monitor their variations, and analyze different scenarios with the aim of assessing the air pollution levels and developing early warning and forecast systems as a means of improving the air quality and safeguarding public health. Such measures can also form part of efforts to achieve a reduction in the number of air pollution casualties and mitigate climate change phenomena. This book contains contributions focusing on remote sensing techniques for evaluating air quality, including the use of in situ data, modeling approaches, and the synthesis of different instrumentations and techniques. The papers published in this book highlight the importance and relevance of air quality studies and the potential of remote sensing, particularly that conducted from Earth observation platforms, to shed light on this topic

    Air Quality over China

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    The strong economic growth in China in recent decades, together with meteorological factors, has resulted in serious air pollution problems, in particular over large industrialized areas with high population density. To reduce the concentrations of pollutants, air pollution control policies have been successfully implemented, resulting in the gradual decrease of air pollution in China during the last decade, as evidenced from both satellite and ground-based measurements. The aims of the Dragon 4 project “Air quality over China” were the determination of trends in the concentrations of aerosols and trace gases, quantification of emissions using a top-down approach and gain a better understanding of the sources, transport and underlying processes contributing to air pollution. This was achieved through (a) satellite observations of trace gases and aerosols to study the temporal and spatial variability of air pollutants; (b) derivation of trace gas emissions from satellite observations to study sources of air pollution and improve air quality modeling; and (c) study effects of haze on air quality. In these studies, the satellite observations are complemented with ground-based observations and modeling

    Spatial Information Technology Based Modeling Approach for Air Pollution Assessment

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    It is an accepted fact that our atmosphere bears an increasing load of pollutants: carbon dioxide, ozone, oxides of nitrogen and sulfur, volatile organic compounds (VOCs), particulates, and heavy metals. The adverse health and environment effects of air pollution have been a major concern in shaping our environmental quality. The World Health Organization (WHO) estimates that 1.5 billion people living in the urban areas throughout the world are exposed to dangerous levels of air pollution and 2 million premature deaths occur annually. A year shortening of life expectancy by an average is also the result of air pollution. Air pollution risk assessment, especially in urban areas, is currently one of the most important environmental issues for human health. Air quality model is a useful tool to simulate the complex dispersion of pollutants in the atmosphere and to predict the long-term effects on ground and spatial levels, and it plays an important role in air pollution risk assessment. Since there are inherent complexities and uncertainties associated with land use information, meteorological conditions, emission spatial allocation, as well as physical and chemical reactions in air quality modeling, it still needs to be further explored. The emergences of new spatial information technologies, such as satellite remote sensing technology and Geographic Information Systems (GIS) open a new era for air quality modeling and air pollution risk assessment, making it possible to predict the spatial concentration distributions of air pollutants on larger scales with finer details. The objectives of the work in this thesis include the development of GIS-based air quality modeling system to predict the spatial concentration distributions of ambient air pollutants (PM2.5, NO2, SO2, and CO), the development of satellite remote sensing approach to retrieve aerosol optical depth (AOD) and to derive ground-level pollutant concentrations (PM2.5 and NO2), and the development of fuzzy aggregation risk assessment approach to evaluate the health risks of multiple air pollutants. A GIS-based multi-source and multi-box (GMSMB) air quality modeling approach is developed to predict the spatial concentration distribution of four air pollutants (PM2.5, NO2, SO2, and CO) for the state of California. A satellite remote sensing approach is investigated to derive the ground-level NO2 concentrations from the satellite Ozone Monitoring Instrument (OMI) tropospheric NO2 column data for the same location and same period. The GMSMB modeling and satellite-derived results are cross-verified through comparing with each other and with the in-situ surface measurements. Furthermore, a fuzzy aggregation-ordered weighted averaging (OWA) risk assessment approach is developed to evaluate the integrated health risks of the four air pollutants. An improved aerosol optical depth (AOD) retrieval algorithm is proposed for the MODIS satellite instrument at 1-km resolution. In order to estimate surface reflectances over variable cover types, including bright and dark surfaces, a modified minimum reflectance technique (MRT) is used. A new lookup table (LUT) is created using the Second Simulation of the Satellite Signal in the Solar Spectrum (6S) Radiative Transfer Code for the presumed aerosol types. The MODIS-retrieved AODs are used to derive the ground-level PM2.5 concentrations using the aerosol vertical profiles obtained from the GEOS-Chem simulation. The developed method has been examined to retrieve the AODs and evaluate the concentration distribution of PM2.5 over the city of Montreal, Canada in 2009. The satellite-derived PM2.5 concentrations are ranging from 1 to 14 µg/m3 in Montreal, which are in good agreement with the in-situ surface measurements at all monitoring stations. This suggests that the method in this study can retrieve AODs at a higher spatial resolution than previously and can operate on an urban scale for PM2.5 assessment. Furthermore, the ground-level PM2.5 concentrations and corresponding health risks are investigated using the retrieved AOD from the satellite instruments of MODIS and MISR for the extended East Asia, including China, India, Japan, and South Korea. The results are validated with the monitoring values and literatures. Depending on the regression analysis, the GDP growth rates, population growth rates, and coal consumptions are the main reasons of the higher PM2.5 concentrations in Beijing. Some mitigating measurements are then proposed and the future trend is predicted. The developed method can be used to other regions for making cost-effective strategy to control and improve air pollution

    From photon paths to pollution plumes: better radiative transfer calculations to monitor NOx emissions with OMI and TROPOMI

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    Nitrogen oxides (NOx = NO + NO2) play an important role in atmospheric chemistry, therefore affecting air quality and Earth's radiative forcing, which impact public health, ecosystems and climate. Remote sensing from satellites in the ultraviolet and visible (UV-Vis) spectral range results in measurements of tropospheric NO2 column densities with high spatial and temporal resolution that allow, among many applications, to monitor NO2 concentrations and to estimate NOx emissions. NO2 satellite retrievals have improved extensively in the last decade, together with the increased need of having traceable characterization of the uncertainties associated with the NO2 satellite measurements. The spatial resolution of the satellite instruments is improving such that the observed NO2 pollution can now be traced back to emissions from individual cities, power plants, and transportation sectors. However, the uncertainty of satellite NO2 retrievals is still considerable and mainly related to the adequacy of the assumptions made on the state of the atmosphere. In this thesis we have improved the critical assumptions and our understanding in the radiative transfer modelling for NO2 satellite measurements, and we use the new TROPOMI NO2 measurements to quantify daily NOx emissions from a single urban hot spot. The work presented in this thesis contributes to the satellite remote sensing community (1) because of the improvement of the satellite retrieval and the knowledge of its main uncertainty sources (Chapter 2, 3 and 4), and (2) because of the application of TROPOMI NO2 measurements for the first time to infer daily NOx emissions at urban scales (Chapter 5). </p

    Acute cardiovascular mortality in communities surrounding an international airport: triggering effects of aircraft noise, temperature, and air pollution

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    Environmental risk factors and cardiovascular diseases are among the leading causes of the global burden of disease. While the importance of transportation noise on health is being increasingly recognized, evidence is still lacking on the role of aircraft noise on cardiovascular health outcomes. In addition, it remains unclear whether aircraft noise can also act as a trigger of cardiovascular deaths, as observed for other environmental exposures such as air pollution. The overall aim of this thesis was to investigate the role of night-time aircraft noise on acute cardiovascular mortality. Individual exposure to aircraft noise, air pollution, and temperature was calculated at home location with high spatial and temporal precision for 24,886 cases of cardiovascular deaths from the Swiss National Cohort occurring in the vicinity of Zurich airport between 2000 and 2015. This ‘case only’ study enabled the investigation of aircraft noise as a trigger of cause-specific cardiovascular mortality with minimum bias. The creation of an individual aircraft noise exposure assessment approach and precise nationwide air pollution models allowed the exploration of the individual and combined effects of extreme temperature and air pollution on acute fatal cardiovascular events. This thesis provides the first evidence of the association between night-time aircraft noise exposure and acute cardiovascular mortality and highlights the importance of undisturbed, quiet nights. Since low average night-time noise levels may mask few loud events, it is essential that future noise guidelines integrate aircraft noise characteristics by using adequate exposure metrics with regards to cardiovascular health outcomes and by promoting the generalization of source-specific regulatory limits. Besides, comparing the risks of cause-specific cardiovascular mortality across several environmental exposures suggested independent triggering effects of aircraft noise, temperature, and air pollution. The association between acute cardiovascular mortality and particulate matter was confounded by nitrogen oxide, highlighting possible singularities in air pollutant mixtures in this particular setting located near a major airport. Finally, differences were observed in exposure levels and susceptibility across the different exposures and health outcomes, which are likely to take root in housing, physiological, social, and behavioural mechanisms. Air travel will continue to be an important driver of development and economic growth. The results presented in this thesis underline the importance to address the public health impacts of aircraft noise at a policy-level and set the foundations to refine future aircraft noise regulations. In the context of a rapidly changing climate, public health and mitigation measures should be integrated in a comprehensive approach to improve environmental health as a whole and to promote sustainable, healthy, and equitable communities

    Radiação atmosférica no ultravioleta no Rio Grande do Sul : fatores determinantes e sua distribuição a partir de dados orbitais

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    A radiação ultravioleta (RUV) desempenha um papel fundamental na fotoquímica da atmosfera, através de processos de absorção ou dispersão por seus constituintes. Quantificar a RUV espaço-temporalmente e conhecer sua relação com variáveis moduladoras é importante para o estado do Rio Grande do Sul, região com um dos maiores índices de neoplasias de pele do Brasil e onde, hoje em dia, são poucas as cidades que monitoram a RUV in situ e raras as que fazem o monitoramento contínuo. Deste modo, o objetivo desta tese foi gerar conhecimento sobre o comportamento local da RUV no intuito de contribuir na tomada de decisões para mitigar os efeitos causados pela exposição a esta radiação. Para isto, abordamos três tópicos: i) avaliamos as variações de poluentes atmosféricos e seu impacto na RUV, num cenário de redução de atividades antrópicas; ii) medimos o potencial do método Random Forest para reconstrução espaço-temporal a longo prazo, combinando dados superficiais e orbitais; iii) estimamos a distribuição espaço-temporal da RUV e suas relações com fatores moduladores. Nossos resultados mostram que em um cenário de redução de atividades antrópicas, as emissões de dióxido de nitrogênio diminuíram, enquanto os níveis de ozônio total e ultravioleta aumentaram; o aumento simultâneo de ozônio e ultravioleta sugerem que o ozônio não é o único fator que influencia a radiação ultravioleta na superfície. Tendo em vista que as estações de monitoramento ambiental existentes no Rio Grande do Sul são esparsas e distribuídas de forma desigual, foram usadas tecnologias como o método Random Forest, em combinação com uma extensa coleta de dados de múltiplos parâmetros de satélite e estações terrestres como uma ferramenta válida para prever variáveis ao nível do solo, bem como reconstruções espaço-temporais a longo prazo. Através de dados de sensoriamento remoto pudemos analisar as características espaço-temporais, determinando-se que no Rio Grande do Sul locais em latitudes mais baixas e altitudes mais elevadas apresentam maiores incidências de radiação ultravioleta; há um padrão temporal bem definido, com maior valor no verão e menor valor no inverno. Mostrou- se ainda que ocasiões de incidência da radiação mais intensa são correlacionadas de forma negativa com ozônio total, e de forma variável com dióxido de nitrogênio total.Ultraviolet radiation (UVR) plays a fundamental role in the photochemistry of the atmosphere, through processes of absorption or dispersion by its constituents. Quantifying UVR spatio-temporally and knowing its relationship with modulating variables is important for the state of Rio Grande do Sul, a region with one of the highest rates of skin neoplasms in Brazil and where, nowadays, few cities have in situ UVR monitoring and even fewer have continuous monitoring. Thus, the objective of this thesis was to generate knowledge about the local behavior of UVR aiming to contribute to decision-making to mitigate the effects caused by exposure to this radiation. This was approached in three ways: i) we evaluated the variations of atmospheric pollutants and their impact on UVR, in a scenario of reduction of anthropic activities; ii) we measured the potential of the Random Forest method for long-term space-time reconstruction, combining surface and orbital data; iii) we estimated the space-time distribution of UVR and its relationship with modulating factors. Our results show that in a scenario of reduced human activities, nitrogen dioxide emissions decreased, while total and ultraviolet ozone levels increased; the simultaneous increase of ozone and ultraviolet suggests that ozone is not the only factor influencing ultraviolet radiation at the surface. Considering that the existing environmental monitoring stations in Rio Grande do Sul are sparse and unevenly distributed, technologies such as the Random Forest method were used in combination with extensive data collected from multiple satellite parameters and ground stations as a tool for predicting ground-level variables as well as long-term spatio-temporal reconstructions across the study area. Through remote sensing data, we were able to analyze the spatio-temporal characteristics, determining that, in Rio Grande do Sul, locations at lower latitudes and higher altitudes have higher incidences of ultraviolet radiation; there is a well-defined temporal pattern, with a higher value in the summer and a lower value in the winter. It was also shown that occasions of more intense radiation incidence are negatively correlated with total ozone, and in variably forms with total nitrogen dioxide
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