Wildland fire is a natural part of the earth’s phenomenological pattern and like most natural phenomena has presented a challenge to human activity and engineering science. Wildfire presents Fire Safety Engineering with the task of developing fundamental research and designing analysis tools to address fire on a scale where interactions with atmospheric and terrestrial conditions dominate fire behavior. The research work presented in this thesis addresses a fundamental research issue involving transport processes in porous wildland fuel beds. This research project had the specific goal of developing an understanding of how transport processes affected the combustion of wildland fuels that were in the form of a porous bed. No detailed study could be found in the literature that specifically addressed how the fuel structure affected the combustion process in these types of fuels. To this end, a series of experiments were designed and carried out that approached the understanding of this problem using commonly available fire testing equipment, specifically the cone calorimeter and the FM Global Fire Propagation Apparatus. The goal of this research study and the basis for the novel and relevant contribution to the field of engineering was to conduct an experimental test series, analyze the data and examine the scalability of the results, to determine the effect of transport processes on the Heat Release Rate (HRR) of porous wildland fuels. The project concluded that flow dominates HRR in fires involving the wildland fuels tested. A dimensionless analysis of the fuel sample baskets showed consistency with well established mass transfer, fluid flow and chemical kinetic relationships. The dimensionless analysis also indicates that the experimental results should be scalable to similar configurations in larger fuel beds. One conclusion of this study was that wildland fire modeling efforts should invest in understanding flow conditions in fuel beds because this behavior dominates over the chemical kinetics of combustion for predicting HRR which is an important parameter in fire modeling.

The use of numerical tools in fire safety engineering became usual nowadays and this tendency is expected to increase with the evolution of performance based design. Despite the constant development of fire modelling tools, the current state of the art is still not capable of predicting accurately solid ignition, flame spread or fire growth rate from first principles. The condensed phase, which plays an important role in these phenomena, has been a large research area since few decades, resulting in an improvement of its global understanding and in the development of numerical pyrolysis models including a large number of physical and chemical mechanisms. This growth of complexity in the models has been justified by the implicit assumption that models with a higher number of mechanisms should be more accurate. However, as direct consequence, the number of parameters required to perform a simulation increased significantly. The problem is when the uncertainty in the input parameters accumulates in the model output beyond a certain level. The global error induced by the parameters uncertainty balances the improvements obtained with the incorporation of new mechanisms, leading to the existence of an optimum of model complexity. While one of the first modelling tasks is to select the appropriate model to represent a physical phenomenon, this step is often subjective, and detailed justifications of the inclusion or exclusion of the different mechanisms are infrequent. The issue of how determining the most beneficial level of model complexity is becoming a major concern and this work presents a methodology to estimate the affordable level of complexity for polymer pyrolysis modelling prior ignition. The study is performed using PolyMethylMethAcrylate (PMMA) which is a reference material in fire dynamics due to the large number of studies available on its pyrolysis behaviour. The methodology employed is based on a combination of sensitivity and uncertainty analyses. In the first chapter, the minimum level of complexity required to explain the delay times to ignition of black PMMA samples at high heat flux levels is obtained by exploring one by one the effect on the condensed phase of several mechanisms. It is found that the experimental results cannot be explained without considering the in-depth radiation absorption mechanism. In the second chapter, a large literature review of the variability associated with the main parameters encountered in pyrolysis models is performed in order to establish the current level of confidence associated with the predictions using simple uncertainty analyses. In the third chapter, a detailed analysis of the governing parameters (parametric sensitivity) is performed on the model obtained in chapter 1 to predict the delay time to ignition. Using the ranges obtained in chapter 2 for the input parameters, a detailed uncertainty analysis is performed revealing a large spread of the numerical predictions outside the experimental uncertainty. While several parameters, including the attenuation coefficient (from the in-depth radiation absorption mechanism), present large sensitivity, only a few are responsible for the large spread observed. The parameter uncertainty is shown as the limiting step in the prediction of solid ignition. In the fourth chapter, a new methodology is developed in order to investigate the predominant mechanisms for the prediction of the transient pyrolysis behaviour of clear PMMA (no ignition). This approach, which corresponds to a mechanism sensitivity, consists of applying step-by-step assumptions to the most complex model used in the literature to model non-charring polymer pyrolysis behaviour. This study reveals the relatively high importance of the heat transfer mechanisms, including the process of in-depth radiation. In the fifth chapter, an investigation of the uncertainty related to the calibration of pyrolysis models by inverse modelling is performed using several levels of model complexity. Inverse modelling couples the experimental data to the model equations and this dependency is often ignored. Varying the model complexity, this study reveals the presence of compensation effects between the different mechanisms. The phenomenon grows in importance with model complexity leading to unrealistic values for the calibrated parameters. From the performed sensitivity and uncertainty analyses, the mechanism of in-depth absorption appeared critical for some applications. In the sixth chapter, an experimental investigation on specific conditions impacting the sensitivity of this mechanism shows its large dependency on the heat source emission wavelength when comparing the two heat sources of the most used pyrolysis test apparatuses in fire safety engineering. More fundamental investigations presented in the seventh chapter enabled to quantify this dependency that needs to be considered for modelling or experimental analyses. The impact of the heat source on the radiation absorption (depth and magnitude) is shown to be predictable thanks to the detailed measurements of the attenuation coefficient of PMMA and the emissive power of the heat sources. The global uncertainty associated with the input parameters, extracted either from independent studies or by inverse modelling, appears as a limiting step in the improvement of pyrolysis modelling when a high level of complexity is implemented. A combination of numerical (sensitivity and uncertainty) analyses and experimental studies is required before increasing the level of complexity of a pyrolysis model.

The overall aim of the present study was to contribute to the argument put forward by Burt, Chmiel and Hayes (2009) that trust in the context of employee selection and training can be negative for safety. The present study builds on these authors argument that new employees pose a safety risk and any effort to build trust in the safety behaviours of new team members and/or to reduce perceptions of the safety risk of new employees (e.g. through selection and training) could likely have negative consequences. The research was conducted in eight organisations from the manufacturing, construction, engineering and rail industries which are characterised by high accident rates (Statistics New Zealand, 2008). There were 118 participants which completed an anonymous occupational safety questionnaire. The participants were employees who worked in teams in high risk industries characterised by a history of turnover. The results supported past findings in that trust in selection and training was positively correlated with immediate trust in new team members. There were mixed results regarding the hypothesis that trust in selection and training is negatively correlated with perceived risk from new team members. In particular there was some support for this hypothesis at the highest job risk level. The results supported the hypothesis that there is a positive correlation between the number of selection and training processes used by organisations and immediate trust in new team members. The results also indicated that the previous safety outcomes of new team members acts as a mediator between trust in selection and training, and immediate trust in new team members. Results are discussed in terms of the concerns and implications for organisations aiming to reduce accident rates.

This study investigated teacher targeted bullying in primary schools to examine whether students serve as an unsafe work stressor for teachers, because teacher targeted bullying is on the rise. This study looked at teacher targeted bullying as an antecedent of stress and the mechanisms, such as mediators and moderators, which affected this bullying-stress relationship. 113 primary school teachers completed a self-report questionnaire which measured bullying, self-efficacy, safety climate perceptions, social support and stress. The results provided evidence that social support from others outside work moderated the mow level bullying-stress, and severe bullying-stress relationships. Most importantly, unsafe job perceptions mediated the relationship between low level bullying and stress. The results of this research imply that student bullying can influence teachers to perceive their job as unsafe and lead to stress. These findings can be used to develop effective strategies to not only prevent and manage bullying, but create safer schools for teachers and pupils.

The aim of this study was to measure the effects of video self-modelling on three children with dog fears aged between 7 and 13 years old. The study also aimed to teach these three children appropriate dog safety techniques and dog body language identification skills which they could use in everyday life. All three participants were recruited through school newsletters. The three participants attended two meetings with the researcher to discuss their dog fears and what they wanted to achieve from taking part in the study. Videos of each participant were then created to depict the participants being within the same environment as a dog while acting calm and displaying coping skills. Participants were also given hypothetical scenarios of where they may encounter a dog and were asked to rate their fear level. A book was created to teach the participants how to read a dog’s body language and how to behave around dogs. Participants viewed their videos and read their books for two weeks. They then went back to the same setting of the video with a real life dog and were asked to rate their fear levels for the same hypothetical scenarios. Results showed an overall decrease in reported fear levels in two of the three participants, with the third participants showing variable fear levels. It can be concluded that the video along with the book had positive effects on the participants’ fear levels and knowledge about dog behaviour. One major limitation of this study is whether the video or the book alone or a combination of both was responsible for the participants’ results and behaviour changes.

The Department of Building and Housing is currently developing a performance framework that will, if adopted, provide a compulsory methodology for performance based fire engineering designs to prove compliance with the fire safety requirements of the New Zealand Building Code. The conceptual performance framework currently includes eight design fire scenarios, fire loads for particular building uses, and tenability criteria for the life safety of occupants. As the level of fire safety within the Code is not explicit, the Department of Building and Housing determined that the performance framework for fire should ensure buildings are designed and built to provide the same level of safety as if they complied with the current Compliance Document for New Zealand Building Code Fire Safety Clauses, C/AS1. This work analysed 12 buildings with a range of uses, which comply with the current C/AS1, using the conceptual performance framework to provide a risk comparison for life safety. Accepted, previously established calculation and modelling methods were used to test the case buildings to the performance framework. None of the buildings met the pass criteria proposed for life safety. Consequently, to comply with the performance framework, a building would be required to be designed to a higher level of safety than is currently accepted to meet code. This shows the current proposal provides a more onerous design regime for fire safety for buildings than the current C/AS1. The results of this research show the conceptual performance framework for fire safety is not ready to be included into New Zealand building regulations in its present form. Furthermore, protection from fire for primary structural members and systems, to protect against building collapse, and tenability criteria and fire fighting access for fire fighters needs to be developed and included in the framework.

Four focus groups were conducted in Kentucky to evaluate differences in the participants knowledge of safe food handling practices, where they obtained their knowledge, which source(s) they trusted to provide accurate food safety messages and the effectiveness of messages from three different sources. The sources of food safety messages compared by the focus groups were the Partnership for Food Safety Educations FightBAC! material, food safety materials developed by the American Dietetic Association and funded by ConAgra Foundation and food safety materials developed by the University of Kentucky. Each focus group represented a specific population, (A) limited resource parents (Louisville); (B) married males (Lexington); (C) mothers of young children (Danville); and, (D) females of varied age with background of Cooperative Extension Service sponsored consumer education in food preparation (Lexington). Follow up interviews were conducted through a telephone survey to inquire as to whether any food safety practices had been implemented since participation in the focus groups. The results of the interview revealed that participants expressed varying familiarity with safe food handling practices, varying understanding of the food safety messages and diverse acceptance and preference for the delivery mechanisms.

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The core theme of this thesis is the potential contradiction between the objective of economic growth in terms of the sustenance of the natural environment and human health. The basic research theme is the identification of the underlying political and economic processes that relate to rising air pollution and corresponding ill-health in cities. It explores the relationship between air pollution and child ill-health in Houston, a highly developed US city. The analysis points out that since the early 1900s, there has been rampant unregulated economic growth in Houston and that weak environmental protection has contributed to both past and current concentrations of industrial pollution, the net result of which is that the environment is severely damaged and human health is deleteriously affected. The thesis indicates theoretical and epistemological limitations in emerging interpretations and highlights that air pollution and ill-health are not simply physical or social problems but they reflect the integration of biological mechanisms and political and economic priorities. This thesis reconceptualizes the connection between the economy and the environment, integrates abstract and empirical investigation, defines the structural character of spatial relations, combines global economic processes with local patterns of environmental degradation, and links historical growth to ecological and health changes. The field-work consisted of a large comparative household survey to examine local air pollution and child ill-health. It was informed by investigations of institutions and documents and complemented by semi-structured interviews. Clusters of child ill-health were found in low-and high-income households in areas near petrochemicals. While it is clear that the socio-economic circumstances of each household influenced the state of child health, this study demonstrates that spatial relations also played a significant role in the relationship. The procedures and analyses are conceptualized through a critical realist methodology, contextualized in a political-economy approach and framed within a theoretical perspective of historical social relations.

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