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A large epizootic of the vector-borne disease bluetongue occurred in northern Europe from 2006-2009, costing the economies of the infected countries several hundreds of millions of euros. During this time, the United Kingdom (UK) was exposed to the risk of bluetongue by windborne incursions of infected Culicoides biting midges from the northern coast of mainland Europe. The first outbreaks which occurred in the UK in 2007 were attributed to this cause. Although bluetongue virus (BTV) no longer appears to be circulating in northern Europe, it is widely suggested that it and other midge-borne diseases may emerge again in the future, particularly under a changing climate. Spread of BTV is strongly influenced by the weather and climate however limited use has been made of meteorologically based models to generate predictions of its spread to the UK. The extent to which windborne BTV spread can be modelled at timescales from days to decades ahead, to inform tactical and strategic decisions taken to limit its transmission, is therefore examined here. An early warning system has been developed to predict possible incursion events on a daily timescale, based on an atmospheric dispersion model adapted to incorporate flight characteristics of the Culicoides vectors. The system’s warning of the first UK outbreak in September 2007 was found to be greatly beneficial to the UK livestock industry. The dispersion model is also shown to be a useful post-outbreak epidemiological analysis tool. A novel approach has been developed to predict BTV spread into the UK on climate-change timescales as dispersion modelling is not practical over extended periods of time. Using a combination of principal component and cluster analyses the synoptic scale atmospheric circulations which control when local weather conditions are suitable for midge incursions were determined. Changes in the frequency and timing of these large scale circulations over the period 2000 to 2050 were then examined using an ensemble of regional climate model simulations. The results suggest areas of UK under the influence of easterly winds may face a slight increase in risk and the length of the season where temperatures are suitable for BTV replication is likely to increase by around 20 days by 2050. However a high level of uncertainty is associated with these predictions so a flexible decision making approach should be adopted to accommodate better information as it becomes available in the future.

In the context of an increasing production of industrial toxic substances (TIC; Toxic Industrial Compound), the risk of accidental release of hazardous substances is growing in spite of the gradual implementation of safer technological processes and safety improvement measures. To mitigate the consequences of chemical accidents or to prepare preventive protective measures before the accident, it is necessary to know or at least estimate the course of accidents. In particular, it applies to the range of traumatic events and fatal accidents. One of the tools that can express the impact of accidents is modelling programs. This diploma thesis presents a comparison of outputs from two special types of software ? a foreign program the ALOHA and the TerEx developed in the Czech Republic. The purpose of the thesis was to indicate theoretical aspects related to gaseous toxic substances diffusion in the ground atmospheric layer and to describe modelling of their ill effects range. To achieve this objective, scientific literature and consultation with experts were used. The practical section of the thesis aimed at determining to what extent the results of both programs differ when initial conditions were identical. To achieve this goal, the intercomparison of outputs (e.g. hurtful concentration range) of the two programs that provided results for the same input data sets (type and quantity of hazardous substances, environmental temperature, wind speed, degree of cloud cover, weather stability class, type of ground surface) was used. After the assessment of the comparison it is possible to generalize the results stating that the software ALOHA compared to the TerEx is more conservative, which means that the ALOHA software provides longer anticipated ranges of danger. Therefore, it depends on the user (the person responsible ? crisis manager, intervention commander, mayor of the village), which approach they select or recommend ? to prepare a greater or a smaller area for a possible accident (to ensure public awareness, to implement technical measures to mitigate the impact of that accident, to assess the amount of financial resources, etc.). As a subsequent step it would be appropriate to verify the theoretical results experimentally, by field testing, which would be conducted under the same meteorological conditions under which the modelling was made by the mentioned programs. This would thus confirm the legitimacy of the special software use for the purpose of estimating the range of negative effects of chemical accidents.

An emission inventory tool for estimating SO2, NO2, and PM10 emissions from brick clamp kiln sites was developed from investigations performed on three representative South African clamp kiln sites in order to facilitate application for Atmospheric Emission Licenses (AELs) from these sources. The tool utilizes readily available site-specific parameters to generate emission factors for significant activities that emit the aforementioned pollutants. PM10 emission factors for significant processes were developed using empirical expressions from the Compilation of Air Pollutant Emission Factors (AP-42) documents. SO2 emission factor for clamp kiln firing was obtained from “reverse-modelling”, a technique that integrates ambient monitoring and dispersion modelling (using Atmospheric Dispersion Modelling System software) to “standardize” actual emission rate from an assumed rate of 1 g/s. The use of multiple point sources proved to improve the simulation of the buoyancy-induced plume rise; therefore, a “bi-point” source configuration was adopted for the kiln. The “reverse-modelling” technique and “bi-point” source configuration produced SO2 emission rates differing from -9 % to +22 % from mass balance results, indicating that the “reverse-modelling” calculations provide reliable emission estimates for SO2. An NO2 emission factor could not be obtained from the “reverse-modelling” technique due to experimental errors and the significant effect of NO2 emissions from other onsite air emission sources such as internal combustion engines. The NO2 emission factor was obtained from previous comprehensive study on a similar clamp kiln site. The emission factors obtained from this study were utilized in developing an “emission inventory tool” which is utilized by clay brick manufacturers in quantifying air emissions from their sites. Emissions quantification is a requirement for brick manufacturers to obtain an AEL which is regulated under South African environmental laws. It is suggested that the technique used here for SO2 emission confirmation could be used to estimate emissions from a volume or area source where combustion occurs and where knowledge of the source parameters is limited. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Chemical Engineering / unrestricted

Cette thèse étudie l’impact de l’Aéroport international de Beyrouth sur la qualité de l’air de Beyrouth et ses banlieues par mesures et modélisation des COVs et NO2. Il s’agit de la première étude qui identifie les signatures des émissions (COVs) issues des avions sous opération réelle. Grâce aux signatures détectées lors de 4 campagnes réalisées, nous constatons que l’aéroport a un impact sur la qualité de l’air de son voisinage, la zone côtière (trajectoire d’atterrissage), et les zones montagneuses. Ces résultats sont confirmés via le modèle ADMS-Airport, utilisé pour la première fois au Moyen-Orient et validé pour les conditions libanaises (r = 0.86). Par ailleurs, les concentrations de 47 COVs ont été mesurées pour la première fois à l'intérieur d’un bâtiment de l'aéroport. Les teneurs en COVs qui sont corrélées au nombre d’avions sont en dessous des valeurs seuils sauf pour l'acroléine alors que la celle de NO2 peut constituer un danger pour la santé. / This work mainly investigated the impact of Beirut Airport on the air quality of Beirut and its suburbs via both measurements and modeling of VOCs and NO2. This is the first study to determine VOC signatures of exhaust emissions from aircraft under real operation. Using these signatures, the impact of the airport activities was tracked in 4 transect campaigns, where it was found that the airport impacts air quality not only in its vicinity, but also on the seashore (landing jet trajectory) and in mountainous areas. These results were confirmed via modeling with ADMS-Airport, implemented for the first time in the Middle East, after being validated in the Lebanese conditions (r = 0.86). As a secondary goal, and for the first time, 47 VOCs were assessed inside an airport building. Measured VOC levels did not present any risks except for acrolein. In the arrivals hall, NO2 levels indicated a health hazard; while a direct relationship was found between aircraft number and VOC concentrations.